holding your engine at full throttle for long periods?

[luke85]

What problems are there with holding a tuned turbocharged car at full throttle and high revs for quite a long time? There is a feature coming up where there is an empty runway and you just see how fast your car can go. Currently running 1.4 bar of boost with water injection and no knock but would this change after 20 seconds of full throttle? problems I see are:

Heatsoak in the intercooler/chargecooler

Overheating of the plugs - is this going to be a problem orare they straight up to temp when you come on boost?

piston cooling - I have no oil sprays, again do these get up to a temperature after a second or 2 or will they be creeping up the longer you spend at full throttle?


Any advive would be much appreciated, maybe its just me worrying because I never really need to spend more than 5 seconds at full throttle and Im fully expecting to melt something

To anyone who knows the engine, if it makes a difference:
low compression C20LET vauxhall engine
Single core chargecooler
Hybrid turbo
2D water injection
heat range 7 NGK irridium plugs
ported and polished head
4x470cc/min injectors
fuelling set by adjustable regulator and wideband to 11.5

[raddy]

Hi
This is pretty complex question, but I think that you mentioned most important points. Generally, engine is on its highest load during top speed runs. To prevent problems during prolonged top speed run you must be sure about oil and water temp, have good knock detection and EGT measurement. Overheating of engine will show increased values of oil and water temp, and probably in EGT. If you will do just top speed test, using at least 1 grade colder plugs like usual (just for test) will be benefit.
So for this purpose is oil and water cooling vital and will determine time of top speed run.
My opinion is that if you have proper tuned engine, values of oil temp,water temp,EGT (and knock as result) will show you time to let off gas...

[JohnA]

Originally Posted by luke85

....low compression C20LET vauxhall engine
Single core chargecooler
Hybrid turbo
2D water injection
heat range 7 NGK irridium plugs
ported and polished head
4x470cc/min injectors
fuelling set by adjustable regulator and wideband to 11.5

1. Low compression as in low-compression pistons? If so, how low, 8:1 would be nice
2. chargecooler will heatsoak early and be of limited use in a long run. Air/air intercoolers have an edge here. I'd go for a large water tank for the chargecooler and a faster pump if possible.
3. Hybrid turbo helps a bit, although you'd need a much larger exh A/R to see a lot of difference at prolonged full throttle, 0.6 or over ideally...
4. W.I. can help a LOT here. Best to configure it to inject at low boost, so you get more water in there during the long run. Also make sure you don't run out of water, normal water tanks don't last too long if you don't let off the throttle

Good luck, the LET is a robust engine, especially with W.I. and if it is not allowed to detonate at all.

I'd also consider injecting pre-turbo as well, it works wonders if your intercooling isn't that good.

[nutron]

People have said that injecting pre-turbo is bad because of the errosion of the turbo. This is true to an extent but If you consider that most vehicles have breather pipes feeding back in to the intake that often chuck in oil mist, the turbo is being erroded all the time. I would not inject pre-turbo as a rule but for restricted periods every now and then it should not decrease the life of the turbo substantially.

[luke85]

Thanks a lot for that guys, Its all been taken on board. I do not have oil sprays for under piston cooling, would this be a problem?

Yes the compression ratio is 8:1