Supercharged Ultimas on race track
Discussion
Hi all,
this year on a track day, I was passed by a Porsche on the straight. This is of course completely unacceptable - I immediatly called my engine guy and we startet looking for a remedy. A bit silly i know, but thats how I got started on that new engine thing and I already had put a little mony aside, since I knew this day would come.
So - a new engine. My power target is in the range of 700-800 hp at the crank (currently around 500hp). I am looking at 2 options: lightweight and high revs or supercharged. A somewhat durable lightweight engine, that can take high revs on a racetrack is quite expensive (even more expensive than a crate LT4/LT5 with all the extras) - but it is possible and I know that we can make that work.
Supercharging on the other hand is more cost effective and needs less revs. But I am unsure about those rising intake temperatures that come with forced induction. I need to be able to complete a 30min. stint on a variety of tracks without heat soak on days as hot as 30°C. Does anybody have experience to share concerning supercharged Ultimas above 700hp, that are driven hard for 30min and longer on race tracks?
this year on a track day, I was passed by a Porsche on the straight. This is of course completely unacceptable - I immediatly called my engine guy and we startet looking for a remedy. A bit silly i know, but thats how I got started on that new engine thing and I already had put a little mony aside, since I knew this day would come.
So - a new engine. My power target is in the range of 700-800 hp at the crank (currently around 500hp). I am looking at 2 options: lightweight and high revs or supercharged. A somewhat durable lightweight engine, that can take high revs on a racetrack is quite expensive (even more expensive than a crate LT4/LT5 with all the extras) - but it is possible and I know that we can make that work.
Supercharging on the other hand is more cost effective and needs less revs. But I am unsure about those rising intake temperatures that come with forced induction. I need to be able to complete a 30min. stint on a variety of tracks without heat soak on days as hot as 30°C. Does anybody have experience to share concerning supercharged Ultimas above 700hp, that are driven hard for 30min and longer on race tracks?
The Porsche was a 991 GT3 RS MK2. Driven properly, these things are ridiculusly fast.
Currently I have a built 6l SBC with 23° heads and a 750 QuickFuel carb. The transmission is a custom built Porsche G64/20 2. I know for sure that the new engine will be EFI and I am leaning more and more to NA. So far I have been unable to find a FI setup for my Ultima that does not incorporate some major compromises in terms of body modification or AC delete, etc.
Currently I have a built 6l SBC with 23° heads and a 750 QuickFuel carb. The transmission is a custom built Porsche G64/20 2. I know for sure that the new engine will be EFI and I am leaning more and more to NA. So far I have been unable to find a FI setup for my Ultima that does not incorporate some major compromises in terms of body modification or AC delete, etc.
humble said:
...I would suggest a naturally aspirated setup over a supercharger mainly for heat management and and track reliability...
My thoughts exactly. Thank you for sharing! I have had a fire supression system in my GTR since i first took it to the track. Never needed it, and I hope I never will. I would recommend it to anybody doing trackdays though. I hope your repairs will be as quick and painless as possible!
845ste said:
exactly the same as my prob.
I have a L98 (ls2 + ls3 head) heavily tuned.
I think 500 / 550whp, but with the gt3 991 there is no story !!!
they also have very good brakes even if they weigh 300kg more than my gtr (I have 6-pot kit brembo , 320mm).
anyway now I'm preparing an NA ls7 with about 700 / 750whp at 8000rpm (I hope ....) with an infinity of modifies to make it reliable for 1h on track !!!!!
forged cranck,,trickflow head, connecting rods, springs, pistons, etc.
I will pay if I will see 750 on dyno !!!
this is the agreement.
supercharger have prob with high temp (very much in gtr in summer specially) and i don't know if is realiable for a 1 h....
in any case, the 991 has a lot of electronic aids, starting with the pdk ....and much more
win easy .......
I have just started the build. We are going to use an SBC block with hybrid heads. The rest of the specs and targets are pretty much the same as yours.
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