Lifespan of a Single

[BrendonD]

TL;DR about MoTeC vs. Megasquirt.

You will screw less up on the MoTeC by virtue of having less things to screw up.

[Mbirt]

Sorry about leaving this discussion for a few days. When not wrenching on the CRF or at my co-op job, I've been on Thumper Talk trying to figure this situation out better.

Thanks for all the info, Drew. My team chose Megasquirt post-comp in '07 when Mahle took their MoTeC back and left us with their 3-cylinder paperweight. The CRF450X was purchased as a desperate plan-B engine in case Mahle didn't deliver their engine before comp in '07. Maybe I'd be running an LT-R on MoTeC too if the team hadn't chosen its future powertrain and controls out of frustration with Mahle.

Aside from starting, Megasquirt's actually been good to us. I've made 44hp at the water brake on an intake runner that was far too long (16.5"--2nd wave at 5000rpm, I do believe) and a small 1L plenum. I took a crack at tuning transients by manually setting the load knob on the brake and rolling into the throttle at various rates. Much to my surprise, it worked and the car was very drivable when the setup was transfered to it. This one particular day last summer is the only stretch of 6 hours in the last two years that we've run completely trouble-free on EFI. I felt every bit of 44hp and it was good. The car ran out of E85 that evening and after we put new fuel in it it just wouldn't start. I can't completely blame the fuel (although it didn't smell as sharply of ethanol as the old E85). It was likely a crank position sensor wiring or coil grounding problem. Nevertheless, we missed the LTU Grand-Prix the next day and ran poorly, but on 100% EFI, at the UofT Shootout.

Back to the present. After pairing the dyno engine's left crankcase half with the race engine's right crankcase half, I got back on the dyno stand and did a few pleasant, trouble-free starts on the carburetor (with MS controlling spark) to get it up to temp and make sure everything was alright. Check. Then came starting on the prototype intake with 3l plenum. After 3 tries with some front-firing on the first two, it started and kept running until I fat-fingered in a 255% VE table entry. The next attempt to start it yielded some more front-firing and then starter geartrain squealing. Great. Please don't let it be the starter clutch.

One EFI start after piecing this motor back together, the "pressed gear," which drives the starter clutch, failed. My research online shows it to be Honda's failsafe in the starter geartrain, albeit a $70-plus one that puts steel particles in the transmission oil. Some posters on various forums have pressed it back together, while other sources say it must be replaced. I've had success re-pressing it once, but it didn't work this time. The starter freewheeled upon installation of the re-pressed gear.

That's enough ventilation on my part. A cam position sensor is needed to prevent front-firing during overlap. I'm also brainstorming ways to prevent the engine from seeing the intake/plenum volume during startup. One way is to go back to a 1l plenum. I'm up to 52hp in GT-Power on a 1l plenum, but it's all near the rev limiter and there's a huge loss in midrange power.

Just in case this thread catches the eye of another team running something other than a 4-cylinder: Do you feel you've found the fatigue life of the major components of your engine? Has it made you reevaluate your engine purchasing scheme? Do you believe buying another new or used motor has saved you money and/or time over doing that second rebuild of an old motor? It would be excellent to have RMIT chime in here.

[ibanezplayer]

Originally posted by Mbirt:
...it started and kept running until I fat-fingered in a 255% VE table entry..

I have fat-fingered many ridiculous things over the years usually killing the engines instantly. I've become a fan of ECUs that have adjustable limits on table entries...

[Kirk Feldkamp]

Another thing of note I've seen on FSAE engines in general is flexible plenums. The ol' alma mater saw it last year on their 600. The prototype plenum they built had a bunch of thin, flat, aluminum sheets welded together. You could easily see the plenum contract at idle, which caused a lot of issues for both starting and staying running after quick off-throttle events. A subsequent redesign for stiffness cured most of the problems they were having up to that point.

Another issue a I've seen a lot of teams struggle with on the singles is injector placement and aiming. On the 600's, it's easy enough to recreate the stock injector mounting geometry, but for (most of) the singles, that simply doesn't exist. Sufficed to say, shooting a stream of fuel directly into a port wall is a poor choice for fueling consistency, but I've seen it more than once. In general, it's best to shoot the fuel directly down the hole(s) and at the back of the valves if possible. Sounds obvious, but I think it's often overlooked.

All I'm trying to say is the EFI setup is an easy target to blame when things don't work, but the design of the rest of the system is just as suspect in many cases.

One last thing... if a huge 255% fat finger occurred and then it wouldn't start again, I'd think that perhaps you wet the spark plug to the point where it wouldn't fire anymore. This sort of thing happens all the time with kart motors after you prime a fuel pump. The cure is usually to remove and dry off the plug, put it back in, and then crank with the throttle wide open until the thing lights off again. There's not enough airspeed to meter any fuel when the carb is wide open, so you're only pumping air in, eventually leaning it out to the point where it will light. For every EFI fuel map I've ever done, I've included a "zero fuel" area at 50%-100% load at the lowest RPM bin (or lowest two depending on how things are set up in relation to cranking RPM). That way, if a driver spins on course (generally resulting in a residual rich condition), he can just put his foot to the floor and crank. The same thing happens as with the kart engine: excess fuel gets exhaled out the exhaust... eventually transitioning to the point where it's lean enough to light off again. This usually works for both hot start and cold-flooded conditions.

-Kirk

[Big Bird]

Hi Mbirt,

I'm by no means an engine expert, but will try to offer some feedback from our side of things.

Agreed that a 20 year life would be unexpected for a 450 single under FSAE conditions. But I think 4-5 years is plenty achievable if you are sensible. And as an aside - sure, the extra mass of a CBR will buy a lot of extra robustness for you, but how many other components of the car get the luxury of the "lets play it safe and make it twice as heavy as it needs to be" philosophy? You rid yourself of a lot of redundant mass by using an engine designed for 55hp - but lose some robustness at the same time. Such is life.

Starter issues - yeah, been there. We were shearing woodruff keys on the crank, an early WR starter problem solved with a Yamaha update part (a spring loaded idle gear between starter motor and crank gear, from memory). It would backfire on starting and just shear the rotor off the crank - occasionally with the rotor "self-machining" a bit more space for itself within the cases. It got a bit expensive before the fix. I don't know what advance we were running, but VFR's advice seems wise.

We've used 3 WR450 engines continuously since 2003, rotated as required. They last saw service for the 2009 car, so 7 cars in total. We've had engine issues at times, but I question sometimes whether the failures were fatigue related, or the result of too many untrained hands fondling the internals.

For 2003 and 2004 the engines were untouched internally, and we never had a problem (aside from starters, above). In 2005, it was decided that we "needed" internal mods (hi-comp pistons, hi-lift cams, etc) and that is when we started to see some major failures. First one - a high comp piston shoved right through the wall of the cylinder when it's skirt dropped off.

We've had some good engine guys through the team since, but they have told of some rather awful handiwork they have found inside those motors. Spacers missing, bolts stripped, cases attempted to be split with screwdrivers and chisels only to find that not all the case bolts had been removed...

These motors can run reliably for the duration of a Paris Dakar Rally or an Oz Safari, and still come back for more. The trick is to treat them well.
- Train a proper engine builder on the team, and follow proper process (assembly done exactly to factory spec and process, every bolt tightened to torque and duly marked, everything inspected and measured where possible, correct tool for job every time, bench kept spotless, NO-ONE aside from the builder touches any component of the open motor etc). Speak to professional engine builders if necessary - listen to what they say.
- Don't try to overcompensate for the smaller motor. You've chosen a small engine, it has advantages (size, weight) and some perceived disadvantages (less power). Play to the advantages and don't fixate on the disadvantages. At best, engine mods might get 2-3hp increase somewhere in the range. At what risk? If you really "need" more than that - then you shouldn't have chosen such a small motor in the first place.
- Obvious, but use good quality oil and change it regularly.
- And if you must change stuff, do it one thing at a time. And in small increments.

I hope the above helps and isn't too sermony. I think you can get a good run out of such things if you do it properly. Good luck with it all.

Cheers

[Big Bird]

Just in case this thread catches the eye of another team running something other than a 4-cylinder: Do you feel you've found the fatigue life of the major components of your engine? Has it made you reevaluate your engine purchasing scheme? Do you believe buying another new or used motor has saved you money and/or time over doing that second rebuild of an old motor? It would be excellent to have RMIT chime in here.

Sorry, should specifically address the questions!

Q. Do you feel you've found the fatigue life of the major components of your engine?
A. We've found the engine life limit after 7 years and about 12-13 comps (3 engines) - that may be fatigue related, but I believe a lot of it is due to imperfect work practice.

Q. Has it made you re-evaluate your engine purchasing scheme?
A. Yes, we have finally bought new engines this year.

Q. Do you believe buying another new or used motor has saved you money and/or time over doing that second rebuild of an old motor?
A. We were onto 4th or 5th rebuilds of old motors. Many times we have argued that the team needed new motors in the past, but the money was redirected to other areas of the car. The engine reliability issue was noted when it started impacting on results.

I hope the above are specific enough, I can't really offer too much more.

Cheers,

[Drew Price]

A. We were onto 4th or 5th rebuilds of old motors. Many times we have argued that the team needed new motors in the past, but the money was redirected to other areas of the car. The engine reliability issue was noted when it started impacting on results.

Keep in mind than when rebuilding singles or twins you can often get NEW cylinders to replace along with new pistons, rather than having to bore / sleeve an inline block.

That along with touch-up work on the crank and new bearings might actually land you with a more 'complete' rebuild than what many people I talk to (consumers and racer types) perceive to be a rebuild, which is often a 'Rings & Bearings' rebuild, which is what I would call a 'Refresh,' not a rebuild.

Sometimes when my shop owner is nearby I call this a 'Peruvian Rebuild'.....

An actual rebuild will usually have you replacing (or at least measuring) the timing components as well.


Drew

[Demon Of Speed]

Originally posted by Big Bird:

These motors can run reliably for the duration of a Paris Dakar Rally or an Oz Safari, and still come back for more. The trick is to treat them well.
- Train a proper engine builder on the team, and follow proper process (assembly done exactly to factory spec and process, every bolt tightened to torque and duly marked, everything inspected and measured where possible, correct tool for job every time, bench kept spotless, NO-ONE aside from the builder touches any component of the open motor etc). Speak to professional engine builders if necessary - listen to what they say.
- Don't try to overcompensate for the smaller motor. You've chosen a small engine, it has advantages (size, weight) and some perceived disadvantages (less power). Play to the advantages and don't fixate on the disadvantages. At best, engine mods might get 2-3hp increase somewhere in the range. At what risk? If you really "need" more than that - then you shouldn't have chosen such a small motor in the first place.
- Obvious, but use good quality oil and change it regularly.
- And if you must change stuff, do it one thing at a time. And in small increments.

I hope the above helps and isn't too sermony. I think you can get a good run out of such things if you do it properly. Good luck with it all.

Cheers

MBirt, read this!

[Mbirt]

Sorry DOS, I created a thread and asked a bunch of questions without a single drop of intent for reading anyone's responses. Especially the responses from a respected and knowledgeable member of a team which I requested a response from. Thanks for bringing it to my attention that I should read the response to a question which I asked.

I do need to pick an engine builder. A grad student with no class load might be perfect for this job. The powertrain design and calibration guy is taking 20 credits this term...

[Mumpitz]

Engine builder: better have grease perma-stained into their hands and an arm that comes with a calibration cert.
Joking aside free time and class standing is the last qualifications to look for. It doesn't matter how busy or how much of scholastic over/under-achiever the person. They need to have the patience dedication and appreciation for the task at hand. The person with the right qualifications will find the time.
If you are dealing with engines that have seen wear and tear it is extremely important to have someone who knows what they are looking at and can spot abnormalities from a mile away, not just follow steps in a service manual.