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drivetrainUW-Platt
06-06-2005, 07:37 PM
So what did you guys all end up with for numbers, found this in the forums: WICKED car from Helsinki, turbo beast makes a reported 113 hp! Not sure on that one, can anyone back that up, I know the land and sea dyno is always kinda wack at competition so....

drivetrainUW-Platt
06-06-2005, 07:37 PM
So what did you guys all end up with for numbers, found this in the forums: WICKED car from Helsinki, turbo beast makes a reported 113 hp! Not sure on that one, can anyone back that up, I know the land and sea dyno is always kinda wack at competition so....

Dan G
06-06-2005, 08:19 PM
UMich-Dearborn

16 rwhp

drivetrainUW-Platt
06-07-2005, 10:19 AM
how much were you making at the crank, I would think that you could lighten/shorten up your drivetrain a lot yet....

CMURacing - Prometheus
06-07-2005, 10:32 AM
reported on our engine dyno: 72 hp
accel run on land and sea's dyno: 63 hp (9 hp inertial drivetrain losses)
steady state pull on land and sea's dyno: 80 hp (8 hp transmission inertial losses)

peak torque was 35-36 ft lbs i believe?

BeaverGuy
06-07-2005, 01:22 PM
This isn't quite comp spec but is close. The dyno was a Superflow 901 in engine in 5th gear 250RPM/sec data every 100RPM.
http://web.engr.oregonstate.edu/~gilletjo/2005dyno.JPG

On the land and sea dyno we hit 60 HP at the rear wheels, and aren't sure of the torque numbers because their RPM pickup was off.

Mikko Kataja
06-10-2005, 09:33 AM
We measured 90,5 at the FSAE land&sea dyno, but the engine wasn't running like it should. We had problems with the ethanol fuel and mixture wasn't what it should be. We tuned the engine while testing it on dyno and it got better and better all the time and when we got the best result engine was really hot and intake air temperature was over 50 celsius.
The best ever result we have measured is 113hp from engine in our own dyno, MAHA rolling road dynamometer and the best rear wheel power has been over 100hp in a Bosch dyno.

Here's our power and torque curves:
http://www.vhtracing.com/HPF005_Power_and_Torque_Curves.jpg

Mikko Kataja
Helsinki Polytechnic

Dan Deussen @ Weber Motor
06-10-2005, 10:53 AM
Mikko,

Just out of curiosity. What kind of acceleration times are you running with this kind of power. I looked and the competition results and I'm guessing that you had issues with the engine at the accelleration event.

I would also be interested to know how driveable your powertrain package is on the track? Your power and torque curves have a huge jump in it, which is typically bad for driveability if you miss a shift and drop below the powerband because the tires will break loose every time you come back on the power band.

B.K.
06-10-2005, 11:52 AM
I was never really an engine guy, plus I've been out of school for four years, so I'm going to have to ask one of you young'uns to help me out.

Let's say you take the equation for power from an engine, that one with all the efficiencies and the heating value and the density and whatnot, ya dig? Use E85's fuel:air ratio, and set the flow rate so that you've choked a 19 mm restrictor. Set all the efficiencies to 1, for the hell of it, except for volumetric which can be a little over 1, right?

If you calculate all that, what is the theoretical maximum power through that restrictor? (This is a calculation everyone does, right?)

What if you set the efficiencies to reasonable "good" numbers, what's the power then?

I admit I am skeptical about 113 horse through that restrictor. 100 even. But perhaps someone will do that calculation and prove to me that it's possible. If, on the other hand, the fuel can't even provide 113 horsepower, there's a dyno in Finland that needs to be calibrated.

I apologize in advance to the Helsinki guys if my gut feel is way off. I never claimed to be a good engineer; Mike Jones will attest to that, I'm sure.

Michael Jones
06-10-2005, 02:15 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by B.K.:
I never claimed to be a good engineer; Mike Jones will attest to that, I'm sure. </div></BLOCKQUOTE>

I never claimed to be either (I fake it the best I can...) so I can't comment on the specifics of Ben's analysis.

We've got close to 100 (usually best runs in the mid-90s, and we expected a bit more this year, but didn't have the time to really figure it out...) We did 76 this year on the L&S, a bit off what we hoped but good given the limited time available for proper tuning.

There is obviously a theoretical maximum, as Ben notes, and a reasonable maximum given standard inefficiencies. 113 sounds high but suspect that tuning for peak HP, damn the consequences, it might happen.

Peak HP is kind of pointless though (and as Geoff advances in his excellent rant, it's likely not the size of the wave but the motion of the ocean, anyway...)

I'm more wondering how do you guys handle a car that doubles power output between 6-7K? It's a pretty common range especially in tight corner exits. Sounds rather jumpy. I'd spin out every time.

Mikko Kataja
06-11-2005, 03:03 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Dan Deussen @ Walbro Engine Management:
Mikko,

Just out of curiosity. What kind of acceleration times are you running with this kind of power. I looked and the competition results and I'm guessing that you had issues with the engine at the accelleration event.
</div></BLOCKQUOTE>

As I mentioned on earlier post we had problems with the ethanol fuel at all dynamic events. It was a really sad thing. We have done so much work tuning the engine and it didn't run at all.. Normally we can easily get times like 4.1s and the traction- and launch control development is just in the beginning..

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
I would also be interested to know how driveable your powertrain package is on the track? Your power and torque curves have a huge jump in it, which is typically bad for driveability if you miss a shift and drop below the powerband because the tires will break loose every time you come back on the power band. </div></BLOCKQUOTE>

Normally when the engine is running well it is pretty easy to handle. It is not so peaky as you could imagine from the figures, even if you drop it under 7000rpm, but it really rocks when you keep it in the range. The drivable range is from 7000 up to 11500 and I think that is pretty wide and it's not hard to keep it in that area while driving.

The next setup will be done with a little smaller charger so it will be better at the bottom end, but it will be really hard to keep the maximum output and top-end power. We don't want to lose those things.. Waiting for the next FSAE measurement! http://fsae.com/groupee_common/emoticons/icon_wink.gif

I don't think we have any problems with our dyno calibration. We have got good results in two different dynos here at Finland and 90,5 at l&s dyno with problems. We have also super flow engine dynamometer, but we haven't measured this last setup in it, maybe next autumn.

Igor
06-11-2005, 10:38 AM
Regarding how to handle a car that jumps so much in power, remember that they live in Finland where there is quite a bit of snow. Grannies take corners sideways on their way to the supermarket.
I remember a couple of years ago it was raining at Formule Student and the Helsinki team was drifting through almost every corner during the endurance. It was awesome.

Igor

jonno
06-11-2005, 10:49 AM
If you believe Renault F1 engine engineers, then the 20mm restrictor is not a restrictor and 120BHP from a naturally aspirated R6 / F4 is feasible. It requires a lot of work though.

syoung
06-11-2005, 01:36 PM
Is this the same leading RenaultF1 engine guy who told us we should be aiming to use all 6 gears for the acceleration event? John's given us some excellent insights, but he's also expressed one or two opinions I'm less keen on.

jonno
06-12-2005, 07:37 AM
yep. And one of his buddies that came down here in January / February was of the same opinion. Which opinions were you not so keen on?

syoung
06-12-2005, 12:06 PM
My main disagreement was the above point about gears.

Let's talk about a target of a four second acceleration run and make the sizeable assumption that first-gear transient launch conditions (slipping the clutch, launch/traction control or whatever) always take up the first 0.8 seconds or so. If an upshift takes ~0.1 seconds - as I understand it, good for a decent solenoid/hydraulic system or a well-practised driver using clutchless manual - that's 0.5 of the last 3.2 or so seconds spent with no drive going to the wheels. Compare this to Chalmers, whose 2003 car did FStudent acceleration (4.1s) in 2 gears, and an almost equally quick run using 2nd gear only.

I don't see that an engine so peaky that it requires 5 upshifts in just over 3 seconds would be particularly driveable in endurance/autocross. Bear in mind that FS/FSAE drivers aren't professionally skilled - the engine won't be kept in the power band all the time around a lap, and having so many gears to go through would at least marginally affect driver concentration and control. Surely it's much better to tune for a flatter torque curve and use fewer upshifts?

Feel free to tear these arguments apart!

VFR750R
06-12-2005, 12:53 PM
Well in Million dollar F1 land with our rules, you would use 6 gears for accel and each shift would take .02 seconds and a computer would use throttle position, road speed, and traction to automatically shift for you. It would perfectly downshift into each corner and shift up on every straight almost like an automatic, totally removing the driver but keeping the engine at maximum possible hp at all times.

Z
06-12-2005, 05:45 PM
Top fuel dragsters do their runs with no gearshifts at all. Just a slipping clutch for half the distance and a bit of tyre growth. They also hit 500kph before 400m which is ~150kph faster than any F1 car has ever run! Of course, that's not a fair comparison, but neither is comparing F1 and FSAE... I'd be inclined to copy the dragsters because they obviously do it better. http://fsae.com/groupee_common/emoticons/icon_smile.gif

Back on topic, 113hp??? 19mm restrictor? Standard E85 fuel? More details on engine please???

Z

VFR750R
06-12-2005, 06:12 PM
Well back in the good ol days of Dynojet at comp we got 81.9hp at the wheels and 89hp back at home. I think the current engine package runs mid 90's on the dyno at home, and I heard 76 at wheels at comp with some less then optimum tuning: all with E85. I've seen 70ftlbs on our dyno at home but we rarely are that agressive with boost at comp. Usually 54-58ftlbs.

Erich Ohlde
06-12-2005, 06:15 PM
93HP at the countershaft on 100 octane. We had ECU sync troubles which made us have to run the engine very rich and when we fixed the problem the day of endurance and tuned on the dyno at competition the dyno guys told us 79 RWHP. I think we may be up to 81-83RWHP now that we've had more tuning time. We are NA and thinking about a turbo for next year.

Plus we had the pleasure of throwing a two foot fireball for about 5 seconds on the dyno following a fifth gear pull decelerating from 14000rpm.

Erick Scarpone
06-12-2005, 06:21 PM
We used a dyno here in caracas and got 88hp on the accel run on land and sea's dyno: 78hp
We didn't get to the steady stated couse we turn of the car and our battery died un us, we had morphy along the way ofall our trip jejeje, we got a peak torque of 38 ft lbs i believe, really dont remember, but the guys at the dyno told us that our curve was the most agresive in the all event and we were the last car on the dyno so we were cand happy about that.
This was our amateur year and if everithing goes weel were goin to do the modification we didnt had time this year to make, the cool things is that the ones we made work out perfectly jejeje, Whatch out for us next year either we break the dyno or we blow our engine!!! jejeje

Vince
06-12-2005, 10:20 PM
I've got a hard time believing the numbers posted on this this subject. Cornell does have a good program, but I stil have a hard time grasping these numbers of 85 hp and higher, even with a turbo. All the turbo does is all you to choke the restrictor sooner. If anyone knows how to make air have a higher velocity than the speed of sound threw the restictor, let me know. Our engine puts out less than 75hp on our dyno at home, but we still manage to win the accleration event. Thats at output shaft of the motor, not at the wheels. Granted the dyno was made in the 1930's, but it does give repeatable numbers.

Vince
2005 Texas A&M Engine Team leader

Marc Jaxa-Rozen
06-13-2005, 12:06 AM
Depending on the control system configuration, shaft alignment and probably phases of the moon (sure seemed like it two days before competition), we've seen as much as 10% variation in absolute figures...so I think numbers taken from different dynos with varying calibrations should be taken with a grain of salt. It's not like peak HP will win anything in this competition, anyway http://fsae.com/groupee_common/emoticons/icon_smile.gif

Marc Jaxa-Rozen
École Polytechnique de Montréal

Mikko Kataja
06-13-2005, 01:22 AM
Have to mention that the first sweep run we did at the l&s dyno at FSAE gave ~76hp. The dyno tuner guy was out of range, and this result was with zero boost pressure. So our engine makes around 76hp from rear wheel 'naturally aspirated' and the engine was not working well at that point, mixture was way out of range. With 0.5bar ~7psi we got that 90,5. When driving at track we have noticed that max boost pressure is somewhere around 0.2bar so the power and torque curves are 'softer' while driving!

Engine is Honda F4i '01, compression ratio 11.5:1 (stock pistons lowered a little from top), Garret T25, boost pressure 0.5bar. Grinded intake cam, ported head, carbon fibre intake manifold with build in air-to-air cooler, 4-1 stainless steel exhaust with a merge collector. Tatech engine management system with AEM CDI multispark ignition and wide band lambda, sequential fuel injection etc.etc.. Basic idea is that with a low boost pressure and pretty high compression ratio + well flowing turbine housing we can get lots of power at wide range even without boost pressure at high rpm. If you look at the curves we have lots of power from around 6700 up to 12000. Intake and exhaust manifolds are tuned to somewhere near 9000rpm and we have tested different cam timings to get best results.

http://www.formula.stadia.fi/kuvat/HPF005_engine.jpg

ben
06-13-2005, 02:32 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by syoung:
Is this the same leading RenaultF1 engine guy who told us we should be aiming to use all 6 gears for the acceleration event? John's given us some excellent insights, but he's also expressed one or two opinions I'm less keen on. </div></BLOCKQUOTE>

Have you read Charlie Ping's paper on shift time limited acceleration from MSEC last year? The guy from Renault is in absolute terms correct but as has been pointed out shift time becomes a big factor for FSAE.

Ben

syoung
06-13-2005, 11:59 AM
No Ben, I haven't: is it available on the web somewhere?

Naturally in an ideal case you would use 6 gears for acceleration (or 9, or 100% efficient CVT, or...) but I was talking strictly in real-world terms - I should have emphasised that. Thanks Ben & Cornell Guy, to whose list I'd also GPS influence of auto shift points. Downshifts would be hard to automate under our rules, of course, with drive-by-wire being banned. (Or am I wrong?). Z, I'll stick to the F1 comparison in this case - at least they're able to take corners!

One more, slightly relevant, point I meant to put in my original post is that, unlike quite a lot of US colleges, we poor UK FStudenters don't have any need to gear for faster than ~65 mph, as there are no practice events to take part in: the cars are ineligible for any MSA event, and university teams have never found time/resources/enthusiasm to organise competitions between themselves. (On a personal note I'd complain that this is a real shame, and ought to change to give more UK teams a chance of a decent performance at FS. I believe IMechE has come to the same conclusion as of this year.)

B.K.
06-13-2005, 01:31 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by syoung:
...unlike quite a lot of US colleges, we poor UK FStudenters don't have any need to gear for faster than ~65 mph, as there are no practice events to take part in: the cars are ineligible for any MSA event, and university teams have never found time/resources/enthusiasm to organise competitions between themselves. </div></BLOCKQUOTE>

But even if events were available to your team that would take the car up to speeds beyond those you'd see in the competition, you wouldn't design for them, would you? You'd still design for the competition, right?

Of course, there's more than a few teams in the US that don't think that way. I guess it comes down to whether your only goal is to win the competition.

Or you could always complain that the competition tracks are too slow.

Charlie
06-13-2005, 04:27 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Vince:
Our engine puts out less than 75hp on our dyno at home, but we still manage to win the accleration event. </div></BLOCKQUOTE>

Accel event is a poor indicator of horsepower, if it were a longer distance it would be much more effective. As it sits cars are traction limited for quite awhile, so tires and weight distribution are very important. Also, gearing comes into play quite considerably.

Our 2004 car, which was built for low-end torque and also suffered from a few less than ideal parts I made http://fsae.com/groupee_common/emoticons/icon_wink.gif put only arouns 62 peak HP to the wheels, but we finished 4th less than a tenth behind the winning car which was Cornell. I'm sure our horsepower was on the low side of the top cars for sure.

I beleive Cornell's numbers. The turbo can be quite effective and they've had years to refine thier design. In my FSAE experience little things add up and with a few years to tweak thier setup I think they are about on the mark. Especially considering the gearing they (appear to) run.

I suspect they make thier HP peak quite low in the RPM range; if it were above the point the restrictor starts to affect airflow in an NA engine, it couldn't be as high.

VFR750R
06-13-2005, 06:02 PM
Our HP peak is normally around 8800rpm and torque peak around 6 but the curve is usually so flat from 5-8500 there is no defined 'peak'. Things behave differently on the chassis dyno then the engine dyno. An engine dyno is nearly steady state allowing all the resonances in the runners and plenum to fully develope where a chassis dyno goes through rpm so fast it has a tendency to knock down the peaks and valleys. In cup racing both types of dynos are important tools for figuring out what the engine is doing.

Also lighter wheels, and diff can have a substantial difference in rear wheel HP due to their intertia on top of internal engine components. That is definitly one of the disadvantages of the longer stroke YZF vs the CBR's and R6's...or is it. We like to think the heavy crank makes the car easier to drive in the lower gears without giving up much in accel. A NA car should be geared lower then a turbo car as well which makes the engine sweep rate faster for a given car accel rate, so we get some of that back by running the car from 6-10000 instead of 8-12000 on the track.

Kirk Feldkamp
06-13-2005, 09:01 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I've got a hard time believing the numbers posted on this this subject. Cornell does have a good program, but I stil have a hard time grasping these numbers of 85 hp and higher, even with a turbo. All the turbo does is all you to choke the restrictor sooner. If anyone knows how to make air have a higher velocity than the speed of sound threw the restictor, let me know. Our engine puts out less than 75hp on our dyno at home, but we still manage to win the accleration event. Thats at output shaft of the motor, not at the wheels. Granted the dyno was made in the 1930's, but it does give repeatable numbers. </div></BLOCKQUOTE>

Do the calc with your theoretical maximum isentropic mass flow with a 20mm restrictor... throw in some actual (or realistic if you don't have the data) lambda and BSFC numbers and find out what your "theoretical power" is. Better yet, take your actual hp, BSFC, and lambda data from the dyno and figure out what your actual mass flow is. I'd be surprised if you really get up to the theoretical isentropic choked flow with a NA setup. With the normal BSFCs and lambdas that we run at Cal it's very possible to make up into the mid-90s, and we have done so quite easily. That puts the engine a little over the ragged edge with our current setup at the top end. This is on non-intercooled GT100 mind you.

The big difference between the turbo vs. NA is the torque you can make with something like a boost controller. Got area under the curve? http://fsae.com/groupee_common/emoticons/icon_smile.gif Although not up to Cornell standards (yet) we were making a very usable 50 ftlb average from 6000 to 10000 rpm. There are a lot of things that will get explored with this years team... pulse tuning, both intake and exhaust, cam timing/overlap, and higher (than our lowered) CR pistons. The pistons should help a bunch as we went pretty low to be safe on our first turbo motor. This is all in an effort to increase increase the area under the curve at lower RPMS.

These turbo engines will be a lot like a WRC engine: CR limited at lower RPM and detonation limited at the top end. Check out the Summer 2004 issue of Race Engine... there is an article on the WRC engines.

Now I'm always up for dyno racing, but it really doesn't matter per se what the final number is. Like has been said a million times, it's tricky to get numbers to line up dyno to dyno, day to day. If you can convince yourself that the dyno is repeatable run to run, then just keep working on improving run to run. If you can't repeat numbers with the exact same setup on your dyno, it's time to work on your dyno, and forget about your car for a bit.

There are a couple good jokes in all of this. In the light cars we run, and the super short straights we see at FSAE, the engine rarely gets a chance to fully load itself and make the power you think you're getting on the dyno. I'd love to see the data of a team with a couple rear axle torque gauges (recorded on course) and compare it to their "expected" dyno numbers. I bet they wouldn't line up very much, if at all. I think we saw a good indication of this with our boost controller logs...

Is all the engine develpment worth it? I'd say so. Who says that since your car can't handle putting down a usable 60 ftlbs yet, that it wont be able to once the suspension/chassis guys get their act together? It's racing guys, you've got to look beyond what you can do right now if you're going to go faster.

MY $0.02. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

-Kirk

ben
06-13-2005, 11:06 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by syoung:
No Ben, I haven't: is it available on the web somewhere?

</div></BLOCKQUOTE>

http://www.sae.org, search for papers from the 2004 Motorsport Engineering Conference (MSEC). You can download it for about $10.

While you're looking check out the paper on tyres by Nick Treverrow from Monash Uni - very interesting stuff.

Ben

LTS110
06-15-2005, 11:55 AM
I have done some minor simple calculations with the usuall assuptions like 100% volumetric eff and no losses in the turbocharger bearings etc.
the 20 mm restrictor should choke at 0.0745 kg/s and assuming a honda F4i engine that peaks at 12500 RPM, the mass flow rate should be (according to my simple calcs) in the region of 0.06 kg/s. Hence, I can't get it how a NA engine can choke the restrictor unless it revs higher than 12500RPM. Hence the use of a T/C unit I assume is just to get that some more air into the cylinders until the restrictot gets choked!
Is the GT12 the best one available? My calculations says so and it matched the 600 cc engine quite well especially on the compressor maps.

rgds
Noel

BeaverGuy
06-15-2005, 03:44 PM
If the air filter-throttle-restrictor was isentropic and adiabatic then I would completely agree. But there are going to be frictional losses in all of those places and it is quite possible that their will be heat transfer from the engine into the air at the restrictor too. All of that leads to a lower maximum mass flow rate through the restrictor. Then there is the fact that the restrictor sees unsteady conditions and will likely be choked for portions of the cycle and not choked for
others.

Tommy99953
09-10-2005, 12:41 PM
From the research i have done, I have found that the maximum mass flow rate through the restrictor is at choke flow, so if u got it, then u are done. I am designing the intake, may be you cna point me in teh right direction? <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Vince:
I've got a hard time believing the numbers posted on this this subject. Cornell does have a good program, but I stil have a hard time grasping these numbers of 85 hp and higher, even with a turbo. All the turbo does is all you to choke the restrictor sooner. If anyone knows how to make air have a higher velocity than the speed of sound threw the restictor, let me know. Our engine puts out less than 75hp on our dyno at home, but we still manage to win the accleration event. Thats at output shaft of the motor, not at the wheels. Granted the dyno was made in the 1930's, but it does give repeatable numbers.

Vince
2005 Texas A&M Engine Team leader </div></BLOCKQUOTE>

Chris Davin
09-10-2005, 02:59 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Vince:
I've got a hard time believing the numbers posted on this this subject. Cornell does have a good program, but I stil have a hard time grasping these numbers of 85 hp and higher, even with a turbo. All the turbo does is all you to choke the restrictor sooner. If anyone knows how to make air have a higher velocity than the speed of sound threw the restictor, let me know. Our engine puts out less than 75hp on our dyno at home, but we still manage to win the accleration event. Thats at output shaft of the motor, not at the wheels. Granted the dyno was made in the 1930's, but it does give repeatable numbers.

Vince
2005 Texas A&M Engine Team leader </div></BLOCKQUOTE>

As has already been pointed out, many factors affect acceleration time besides engine performance, including driver weight and height, vehicle weight, vehicle static rear weight bias, vehicle center of mass height, wheelbase, tires, final drive ratio, inertia of rotating components, aerodynamics, and especially driver skill. We got beaten in the Acceleration event, but two days later, won the acceleration section of the Road and Track competition, with a different driver driving.

No one told you how to get velocity through your restrictor higher than the speed of sound? It's easy. Just put a converging-diverging nozzle with a ~10mm diameter throat upstream of your current restrictor. When the air expands through the diverging outlet, it will be accelerated to much higher velocities by the time it gets to the existing restrictor. It's a trick we high-horsepower teams have been using for years. ;-)

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mikko Kataja:
Have to mention that the first sweep run we did at the l&s dyno at FSAE gave ~76hp. The dyno tuner guy was out of range, and this result was with zero boost pressure. So our engine makes around 76hp from rear wheel 'naturally aspirated' and the engine was not working well at that point, mixture was way out of range. With 0.5bar ~7psi we got that 90,5. When driving at track we have noticed that max boost pressure is somewhere around 0.2bar so the power and torque curves are 'softer' while driving! </div></BLOCKQUOTE>

How did Land and Sea set up the test for you? Were they using the eddy-brake, or was it a purely inertial test? What gear were you in?

DaveC
09-15-2005, 10:08 AM
So, one thing that is not clear, are you (everyone) posting corrected dyno numbers or not? Usually there is a correction factor based on elevation and atmospheric conditions that make it a little easier to try to compare numbers. However, I will point out that all dynos are different, so comparisons done from one dyno vs another, especially if they are a different brand, are almost worthless. Another point is that engines with turbos will produce A LOT more boost on a dyno than on the track (I'm only talking fsae cars). The dyno will place much more load on the motor than the car running on the track will, allowing more boost to be created. Anyway, I do believe the shape of the curve to be more important, and the curves posted here are impressive. It gives us something to work towards... This will be the first year our team will get into internal engine mods instead of running it right from the junkyard http://fsae.com/groupee_common/emoticons/icon_biggrin.gif.

Frank
09-15-2005, 03:18 PM
more shameless self promotion

http://www.uq.edu.au/fsae/frank/engine.jpg

76 Hp at the engine sprocket

Dyno'd on MoTeC's engine dyno

49% front weight (with driver)

MoTeC Traction and Launch Control

UQ.. Acceleration winners @
FSAE- AUS 2004 (4.06, optical beam timed, beam catches nosecone)
F Student 2004 (4.05,transponder timed, device placed at rear of chassis)

Scott Wordley
09-15-2005, 04:56 PM
You forgot to mention that it had no diff to slow you down either. http://fsae.com/groupee_common/emoticons/icon_wink.gif

Frank
09-15-2005, 08:05 PM
yeah, i'm not so sure it makes much of a difference...

but we haven't done a "back to back" test

i can understand if people choose to write off our straight line speed to "not having a diff"

IMO having a good tune helps most.. there are so many lawnmower sounding cars at every comp

im waiting for the obligatory " lazy b^@%@*@# " response..

Superfast Matt McCoy
10-12-2005, 09:47 PM
Well, we just got our Dyno working here in Oklahoma and we've posted some pretty unbelievable numbers:

http://students.ou.edu/B/Matthew.L.Brown-1/DynoNegative.jpg

Hopefully this will translate into negative lap times...

kwancho
10-12-2005, 10:05 PM
Haha, that actually made me laugh.

Psychosis
11-03-2005, 02:30 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Alex Kwan:
Haha, that actually made me laugh. </div></BLOCKQUOTE>

yeah me too...

oh dear...

we're definately engineers !! http://fsae.com/groupee_common/emoticons/icon_confused.gif

D-Train
11-03-2005, 04:29 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">...Garret T25, boost pressure 0.5bar... </div></BLOCKQUOTE>

Isn't that a fairly big turbo for a 600cc engine? If I recall correctly, they were stock turbos from a few different Nissans of the mid-to-late 90's, mostly 2 litre engines (SR20, RB20). It seems like a lot of teams go for the smaller GT12 or GT15 turbos. Is there any particular reason you chose this for your compressor?

(EDIT: just took another look at that pic - looks way too small for a T25. I'm guessing a GT15?)

BTW, nice carbon fibre intercooler piping. Are those end tanks CF too?

Psychosis
11-04-2005, 12:32 AM
Helsinki,

don't mean to be picky (but im allowed to, we dont get 113 odd bhp). your intake manifold rubbers are held on using jubilee clips (from what i can tell in the picture) which if you read the rules http://fsae.com/groupee_common/emoticons/icon_biggrin.gif ain't allowed http://fsae.com/groupee_common/emoticons/icon_smile.gif

Mikko Kataja
12-14-2005, 11:58 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">(EDIT: just took another look at that pic - looks way too small for a T25. I'm guessing a GT15?) </div></BLOCKQUOTE>

It really is/was a T25 at the moment we took this picture, but we changed to T20 before formula student event.. Believe it or not!

And these hp numbers, i'm tired of these comments that it can't be true or the dyno which we used to measure was way out of calibration or something like that.. We have done some work with our new R6 engine at superflow engine dyno and we have pretty good results which are coming pretty close to this ~110hp measured in a bosch chassis dyno from our previous car. And even at really high rpm rising speeds.. ,but we'll see at the l&s dyno at formula sae next spring.. http://fsae.com/groupee_common/emoticons/icon_wink.gif

Mike Cook
12-15-2005, 08:46 AM
Hey guys, we just got done wtih finally getting our engine tuned. It is a f4i with only intake and exhaust. We pulled 83 rwhp. I'll attach some graphs when i finally get them.

D-Train
01-10-2006, 01:54 AM
So... it is the same T25 I was refering to? wow, guess i have to have another look at one, thought they were way bigger than in that pic. No, I'm sure they are bigger... are we talking about the same T25? maybe the nissan ones i'm thinking about aren't garrett...

Sofa King Awesome
01-22-2006, 12:26 AM
I just noticed something odd about the dyno chart from Helsinki on page 1. I'm not 100% certain, but I've always known HP and Torque curves to cross at 5250 rpm and only once. Helsinki's graph here doesn't even include that number. Is it possible for the graphs to cross again later? I think the equation dictates that above 5250 rpms that HP must be greater that torque. Is this correct? Here's an example of a normal, accepted HP-Torque curve:

http://www.geocities.com/jharkola/images/miniturbo/rolling_road_lbft.jpg

Andycostin
01-22-2006, 04:41 AM
Sofa King, I think that you'll find you can change where two graphs cross by changing their axis, what I'd believe to be fairly obvious - but maybe that's just me....

Garlic
01-22-2006, 09:17 AM
5252 when your units are ft-lbs and bhp. On the other graph the torque units are Nm.

Not to mention your graph they don't cross at 5252, more like 5500, because the axis are slightly different.

Sofa King STUPID.... gimme a break.

B.K.
01-22-2006, 12:13 PM
Yeah, dude. Come on.

pengulns2001
01-22-2006, 08:19 PM
how some people get engineering degrees is beyond me

CornellGixxer
02-23-2006, 08:37 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by DaveC:
Another point is that engines with turbos will produce A LOT more boost on a dyno than on the track (I'm only talking fsae cars). The dyno will place much more load on the motor than the car running on the track will, allowing more boost to be created. </div></BLOCKQUOTE>

Turbo lag will always be an issue for turbo cars... but, with proper flow system design, a correctly sized turbo, and a few good EE's we were able to come up to full boost after only a few tenths of a second on the track.

Homemade WRX
02-23-2006, 07:42 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by CornellGixxer:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by DaveC:
Another point is that engines with turbos will produce A LOT more boost on a dyno than on the track (I'm only talking fsae cars). The dyno will place much more load on the motor than the car running on the track will, allowing more boost to be created. </div></BLOCKQUOTE>

Turbo lag will always be an issue for turbo cars... but, with proper flow system design, a correctly sized turbo, and a few good EE's we were able to come up to full boost after only a few tenths of a second on the track. </div></BLOCKQUOTE>
I wish we had some EE's...a lot of people don't realize how important electronics are to getting a responsive/fast spooling turbo motor...

pengulns2001
02-23-2006, 08:14 PM
other than maybe running a electronical operated wastegate i dont see the relation... provided you can hook up an EBC and get it tuned (not really EE territory)

VFR750R
02-24-2006, 10:57 AM
Good wastegate algorithms don't write themselves, you wouldn't believe the man hours gone into designing and developing the wastegate control the team has now. Not to mention good fuel tuning to match it.

So maybe not an EE but a computer science nerd of some sort...which are more often then not from our EE department. It also helps to have complete integration with your spark and fuel tuning...which is alot easier if you design the ECM as well.

CornellGixxer
02-24-2006, 12:19 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by pengulns2001:
other than maybe running a electronical operated wastegate i dont see the relation... provided you can hook up an EBC and get it tuned (not really EE territory) </div></BLOCKQUOTE>

You're right... fast initial spool time can be achieved without electronic aids. Id say that response times could be even faster with a nice mechanical setup than electronic (response times and all). The EE's magic comes in making that boost behave the way you want it to at all RPMs and loading conditions, not just spool.

Homemade WRX
05-01-2006, 08:25 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by pengulns2001:
other than maybe running a electronical operated wastegate i dont see the relation... provided you can hook up an EBC and get it tuned (not really EE territory) </div></BLOCKQUOTE>
true, so long as you have a good Management system...and well, seems as though the cornell guys have filled in the rest of what I was going to say...

Pete M
03-26-2007, 10:16 PM
Sorry to resurrect a dead thread, but i just noticed something.

Helsinki's power curves don't seem to add up. At 9,000 rpm, they claim to make 80 N.m. If i calculate power, i get about 75 kW, or 101 hp, but the power curve at that rpm shows 110 hp. Other sites get similar results. Their whole power curve is approximately 10 hp higher than my calculation based on torque indicates (using 746 W per hp). Are you guys using a different definition of hp? (Some European definition?)

The power they are making is still very impressive, but it no longer seems impossibly high. Or did i stuff something up?

Mikko Ahola
03-26-2007, 10:38 PM
Sorry guys but I don´t know where that graph is taken from but if its from our SuperFlow it tends to correct the Hp but not the Nms. So it could be that... Or not. But you have to also remember that those figures are only present when the throttle is fully open and the boost pressure is at max. We run a 0,65bar boost in HPF006 and most of the time were able to produce only 0,5 at track because there was no grip to make more resistance to engine.

I was also wondering how no one seems to understand our power number because it seems to mee that you can get over 100Hp with N/A engine easily. The driveability would suck thou.

But anyway now we are running our first N/A engine and we are somewhere around 60Nm and 90Hp from the sprocket at the moment. Looks good also as we get over 90% of the max torque from 6000 to 12000. And almost 20kg lighter engine package.

Pete M
03-26-2007, 11:04 PM
I believe the torque figures in the graph on the first page (and the power i calculated from them). Going off them, you're making a bit more power than we are (currently about 94 hp), but we aim to make it at lower rpm. At present, we make that power between about 6,800 rpm and 8,200 rpm, with a slow taper off above that.

Good luck with the NA package.

repeatoffender
03-27-2007, 03:59 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Pete M:
I believe the torque figures in the graph on the first page (and the power i calculated from them). Going off them, you're making a bit more power than we are (currently about 94 hp), but we aim to make it at lower rpm. At present, we make that power between about 6,800 rpm and 8,200 rpm, with a slow taper off above that.

Good luck with the NA package. </div></BLOCKQUOTE>

would you be able to post a picture of your power and torque?

Im interested in the torque firgure your turbo engine can produce? im sure many of us on here would like to know what is possible from a turbo package...

Pete M
03-27-2007, 05:44 PM
We're in the middle of tuning right now, so the curves i've got aren't really representative in the bottom end. I'll post one in a week or so, assuming the other guys agree.

If you want a number though, peak torque is 100 N.m (74 ft.lbs). Needless to say, the engine is quite stressed when making that. I'm a little worried that people will blow up a motor or two trying to match it. People need to understand that getting that number involves more than just upping the boost. I know there are a few teams that make similar torque though. It's not impossibly difficult, I'm just urging people to be careful and make sure they know what they're doing before attempting it.

VFR750R
03-27-2007, 07:30 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Pete M:
We're in the middle of tuning right now, so the curves i've got aren't really representative in the bottom end. I'll post one in a week or so, assuming the other guys agree.

If you want a number though, peak torque is 100 N.m (74 ft.lbs). Needless to say, the engine is quite stressed when making that. I'm a little worried that people will blow up a motor or two trying to match it. People need to understand that getting that number involves more than just upping the boost. I know there are a few teams that make similar torque though. It's not impossibly difficult, I'm just urging people to be careful and make sure they know what they're doing before attempting it. </div></BLOCKQUOTE>

"people" hmm...yeah, we dont umbderstand. we'll try to make sure we know before we be stupid. Dee Dee Dee. You're special. http://fsae.com/groupee_common/emoticons/icon_razz.gif

Pete M
03-27-2007, 07:45 PM
That really wasn't what i meant and i'm sorry if anyone took it that way. There are a lot of very good engine packages in FSAE, and i don't claim in any way that we are superior to them. We got our arses kicked a couple of months ago by an NA 600 and an NA 450 and i have a lot of respect for the people that developed those packages.

There's just a disturbing number of posts on these forums from people who do quite scary things to engines, without understanding why it's dangerous. There is no reason why any team could not make our torque if they decided it was desirable and put some thought into it. The more you try to push things though, the less forgiving everything is. I don't want the responsibility of some rookie team saying that they blew up an engine because of something i said.

I'm sorry if that came off as snobbish.

VFR750R
03-27-2007, 08:12 PM
It's ok, I knew you didn't mean to be, but there are some serious engine guys on here that do understand the limitations and requirements of making big torque.

I know what you mean about this forum. Trying to explain to someone in a few sentences or even paragraphs on the forum what your doing is very difficult without missing something or being misunderstood. Even so, as a newbie to the forum, recognize your words are read word for word with no scarcasim implied.

Pete M
03-27-2007, 08:29 PM
Yeah, hence the apology. I've actually been reading these forums for a few years now and only recently got around to posting.

It's a bit silly to compare dyno numbers anyway. We spend most of our time trying to make the car quicker rather than pulling good dyno numbers. In the last 2 years, we've only added about 6 N m to our peak torque on the dyno. On track, however, we've made massive gains.

A quick word of advice to any new turbo teams: don't pay too much attention to dyno figures unless you can make your dyno ramp at rates that are representative of your car. What you will see on track will likely be different.

repeatoffender
03-28-2007, 01:42 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Pete M:
We're in the middle of tuning right now, so the curves i've got aren't really representative in the bottom end. I'll post one in a week or so, assuming the other guys agree.

If you want a number though, peak torque is 100 N.m (74 ft.lbs). Needless to say, the engine is quite stressed when making that. I'm a little worried that people will blow up a motor or two trying to match it. People need to understand that getting that number involves more than just upping the boost. I know there are a few teams that make similar torque though. It's not impossibly difficult, I'm just urging people to be careful and make sure they know what they're doing before attempting it. </div></BLOCKQUOTE>

Thanks for that, i would really like a graph as im trying to convince my school and this would help.

Wow 100 Nm!!!