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Old 05-22-2012, 06:56 AM   #1
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Default power loss during race. heat soak??

my turbo race car loses power during a 20 min race. according to the data logs it is around 60-70bhp! i can only assume this is due to rising inlet temps but don't have the data from the ecu log. i have a good intercooler and ducting setup so what else can i do?? don't get me wrong the car still pulls well but just seems to lack a little. there is no sudden lack of power it is gradual thought the race and can be seen by comparing the power output in the logs from the start of the race to the end.

oil cooler covering too much intercooler perhaps?

considering water injection but only to keep the temps down and not advancing any timing for extra power. don't like the idea of melting my engine if the system fails. should make a little just from the lower temps but that's not the idea. just be happy to maintain the power i have for the whole race.

surely you some of you guys have the same issues if not worse with the hotter air temps you see.



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Old 05-22-2012, 07:22 AM   #2
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Get a proper datalog from the ECU.
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Old 05-22-2012, 08:23 AM   #3
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did do but when i copied it over i deleted it and it had not copied properly so i lost it. earlier logs show the inlet temps settling at around 52c but that was during testing and was not being driven quite so hard for so long.
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Old 05-22-2012, 08:56 AM   #4
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Can you move the oil cooler to just behind the intercooler? That would definitely help.
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Old 05-22-2012, 08:57 AM   #5
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not really any room for it there. think if i had to move it it would have to go somewhere completely different.
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Old 05-22-2012, 11:19 AM   #6
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Quote:
Originally Posted by Reverant View Post
Get a proper datalog from the ECU.
+1.

Until then, you're just guessing.
Your car looks serious, It'd be a shame to start changing things if you don't know 100% whats causing the power loss.

If your ecu is up to the task, you can have w/i activate only past a certain iat/map.
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Old 05-22-2012, 11:23 AM   #7
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Check my build thread from the last page or so and look at my oil cooler set-up. Thank me later. Stacking heat exchangers simply does not work. Small, ducted heat exchangers...that works.
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Old 05-22-2012, 03:44 PM   #8
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got some testing booked next week so will get a decent data log done then. in the logs i have, driving reasonably hard the inlet temps look fairly decent and stable at 52c. funny thing is the car did the same thing last year with a totally different engine, turbo, rad, intercooler, oil cooler, ducting and the list goes on... had a thought today that it could be the brakes binding slightly when they get hot so will have to check that too.

are there many race cars on here running WI?
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Old 05-22-2012, 05:37 PM   #9
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I've run water injection on other cars. I'm sure the power loss is likely heat soak. I'm putting on water injection this weekend. at least in Nasa you need to get a waver from tech that says you told them and they looked at the system and it is safe. I think they just dont want you venting to air and or you must not run more then 50/50 mix.
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Old 06-19-2012, 03:20 PM   #10
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well got a chance to get a decent data log of about 15 mins hard driving on track (before they kicked me off for being too loud, but that's another story all together) and the inlet temps slowly rose to 60C/140f. judging by the trend i think they would continue to rise too. also checked the ecu and it is set to start pulling timing from 50c/122f which would explain some of the power loss and cause raised egt's further increasing inlet temps meaning even more retard (chain reaction!). highly tempted to fit WI. first job is to move the intercooler off to the side and duct it (and possibly fan?) but with a race coming up soon i need to get this sorted.
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Old 06-20-2012, 04:07 AM   #11
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what egts did you see? what race? I was informed recently that you need to inform NASA tech if you run WI to get a 'Waver" and I believe they prohibit straight meth and or require a bypass vale ( no blow off valve). dont know what your race is but just fyi, something to look into. obviously good reason for the rule, they dont want to see you burn your car up in an invisible ball of flames!
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Old 06-20-2012, 04:13 AM   #12
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ha, just realized I said the same thing one post up, my bad
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Old 06-20-2012, 05:24 AM   #13
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We race in the uk where I don't think there are such rules. Something to look into though.
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Old 06-20-2012, 05:36 AM   #14
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Time to ditch the shitty eBay intercooler for something that actually works on track. The 600hp Precision core in Theseus keeps IATs to an absolute max of ~135*F in 100*F heat after two 100-140mph 5-6 pulls in a row. IATs reach 135*F peak on each pull, then drop as soon as I lift off the throttle. If I had even the slightest semblance of a cold air intake instead of an air filter basically sitting on the turbo, I'm sure I could knock 10 or 15 degrees off of that.
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Old 06-20-2012, 05:47 AM   #15
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The intercooler is a quality item custom made for the car by forge motorsport here in the uk. Not saying it can't be that but it is pretty good. The oil cooler is blocking a lot of flow and feeding it hot air so first I am going to move that then see where we are. I know others are fine without wi. Just need to work out where I am going wrong. Be great to keep all 355hp to the end of a race.

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Old 06-20-2012, 05:57 PM   #16
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I think IATs around 60C is high.

How air tight is your ducting, starting from the mouth of the bumper?
What are your water and oil temps?
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Old 06-21-2012, 08:42 AM   #17
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ducting is pretty well sealed to the bumper but not air tight as the bumber is an easily removable part and comes off with the undertray. coolant temps peak around 100c and oil peaks around 120c.

have now moved the oil cooler off to the side and built a pox on the front to duct it with hoses. hopefully this will do the trick. if not... back to the drawing board.
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Old 06-23-2012, 02:53 PM   #18
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few pics of the ducting i made for the oil cooler. not really happy with it as i dont think it will flow enough air through the cooler. didn't cost anything so it is worth a go. so hopefully should get a chance to give it a try soon. what do you think?? will it work?





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Old 06-23-2012, 04:08 PM   #19
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I like the idea. I was considering doing something very similar, except with larger hoses (left over 3" brake hose) and NACA ducts to feed the tubing. Ideally you want the inlet to be about 33% of the surface area of the heat exchanger. Its hard to tell from the pics but I agree that the inlet area is a little small. It could also be improved by smoothing out the transitions into and out of the hoses.

something like this would probably help
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Old 06-24-2012, 03:55 AM   #20
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How are the pressure differentials across the oil cooler? Is it relatively low pressure on the side we can't see?
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