iddling mixture speed, Vacuum in airbox

[Phil1988]

Hey,

got another question Can someone tell what iddling mixture speed is usefull? Our idling mixture speed is now at round 2500 RPM and we got heat problems very fast.
How long is the time we can start the engine before a start of an dynamic event? When its more than 5 minutes we have real probs.

We got no experience because we are a completly new team.

Has anyone of you meassuered the vaccum in the airbox? I meassuered it last week and got 0.7 bar vacuum.

regards Phil

[Phil1988]

Hey,

got another question Can someone tell what iddling mixture speed is usefull? Our idling mixture speed is now at round 2500 RPM and we got heat problems very fast.
How long is the time we can start the engine before a start of an dynamic event? When its more than 5 minutes we have real probs.

We got no experience because we are a completly new team.

Has anyone of you meassuered the vaccum in the airbox? I meassuered it last week and got 0.7 bar vacuum.

regards Phil

[exFSAE]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Phil1988:
Our idling mixture speed is now at round 2500 RPM and we got heat problems very fast. </div></BLOCKQUOTE>

How on earth...? Even if you didn't have a fan installed (presumably you do) I'm amazed you can overheat within minutes - at idle.

[jlangholzj]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Phil1988:
Hey,

got another question Can someone tell what iddling mixture speed is usefull? Our idling mixture speed is now at round 2500 RPM and we got heat problems very fast.
How long is the time we can start the engine before a start of an dynamic event? When its more than 5 minutes we have real probs.

We got no experience because we are a completly new team.

Has anyone of you meassuered the vaccum in the airbox? I meassuered it last week and got 0.7 bar vacuum.

regards Phil </div></BLOCKQUOTE>

I'd suggest checking that there's something not going on internally with the motor....for you to overheat that fast is very odd. No clue what motor you're running either but we run an 07 R6 with e85 and its typically a good 2-3 mins before our t-stat will open at idle and another 3-4 after that until the fans kick in. It almost sounds like something else is causing it to "overheat"....which also brings up what do you consider to be "overheating" ? for our system 200F is about operating temp...which is "hot" when tihnking in relative terms...but thats normal for the motor.

[TMichaels]

There must be something severely wrong. Are you already driving? I suppose not, because I cannot think of a failure mode (in FSAE applications) in which the engine overheats while idling, but not on the track.

What do you mean with 0.7 bar vacuum?
BTW: The SI unit (which should be mandatory for engineers) for pressure is Pascal.

[Mbirt]

Phil,

If you want us to help you, we need more information. Which engine, do you have a cooling fan, is the cooling system bled, is water coming out of the vent at the pressure cap, what is the cap pressure? Five minutes of idling to a tap water boil-over with no airflow through the radiator does not seam that far out of the realm of possibility.

[JWard]

I agree with Mbirt, especially a single with low mass, and possibly an underspecd rad. Bare in mind a lot of euro teams don't see the need for a fan unlike US teams. I've seen a ktm 525 heat up quickly because the waterjacket of the cylinder had a deposit on it.

To the OP: there's no need to be severely worried unless you're seeing large temps whilst driving - noise test is likely to be the longest period you'll run the engine for whilst sitting stationary (atleast at fsuk anyway).

Words of assurance aside, the guys in this forum will be able to help you diagnose this and work out why she's getting warm so quick - more info please!

[Wesley]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Phil1988:
Hey,

got another question Can someone tell what iddling mixture speed is usefull? Our idling mixture speed is now at round 2500 RPM and we got heat problems very fast.
How long is the time we can start the engine before a start of an dynamic event? When its more than 5 minutes we have real probs.

We got no experience because we are a completly new team.

Has anyone of you meassuered the vaccum in the airbox? I meassuered it last week and got 0.7 bar vacuum.

regards Phil </div></BLOCKQUOTE>

I would check your ignition timing, it sounds like you may be running it retarded. Also, the airbox shouldn't be pulling much of a vacuum unless it's a huge restriction. The carbs are attached directly to the head.

[Rex Chan]

I can tell you what idle engine speed is "normal" for us: 2000 (good - 2011) to 4000 (bad - 2009/10).

If your *cooling system* is overheating, then that's not good. But if that's what you designed it for... We run electric pump and thermo fan, so cooling at idle/revving with no car airflow isn't a problem (runs the battery down though). This works for us on testing (external battery) and comp (internal battery always on the charger).

You can start your engine up as late as you like at comp, so you can avoid overheating that way. But we like hot engines (over fuel economy), so warm ours up plenty.

PS. Unless you mean exhaust heat issues?

[jlangholzj]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Wesley:

I would check your ignition timing, it sounds like you may be running it retarded. Also, the airbox shouldn't be pulling much of a vacuum unless it's a huge restriction. The carbs are attached directly to the head. </div></BLOCKQUOTE>

for us at 1400RPM we're at about 5-10kPa of vacuum. Just to support your point and to give some actual numbers.