[Future1LE]

So I know I will do heads and cam later but for discussion purposes want to know what you think is the highest boost you are comfortable with for a stock heads and cam set up. I have a 2650 with 85mm upper, stock lower, catless headers, toohighpsi port injection for fueling, RF Big gulp, stock heads/cam. Currently making 16# of boost on this setup and probably around 830whp if I had to guess. I am barely spinning the blower and just curious if doing a lower would benefit me or would it be too much.

[JSH]

Your engine can't flow the air that you're making now, so I wouldn't concern myself with spinning the blower harder. You're always going to underperform with stock heads and cam. I don't think you're going to make 830 wheel. Take it down and put it on the dyno and let's see

[Future1LE]

Originally Posted by JSH

Your engine can't flow the air that you're making now, so I wouldn't concern myself with spinning the blower harder. You're always going to underperform with stock heads and cam. I don't think you're going to make 830 wheel. Take it down and put it on the dyno and let's see

Yea I will put it on the dyno eventually. But do consistently run 5.5 60-130 in 1500+ DA on 67-70 degree weather. That's really all I have for power measurement. Just curious what tuners have seen and tuned before. I get its probably not common, but with port injection being more affordable now for some maybe we will see more of them.

[KingLT1]

I read a guy saying he was pushing 23psi with a 2650 on an otherwise stock LT4 with port injection and full E85. You can run more boost since you are going to have the fueling. The engines' ability to flow air was never the limiting factor.

Now keep in mind boost is just a measure of restriction. A stock LT4 pushing 23psi might "only" make 19-20psi with heads and a large cam.

[Future1LE]

Originally Posted by KingLT1

I read a guy saying he was pushing 23psi with a 2650 on an otherwise stock LT4 with port injection and full E85. You can run more boost since you are going to have the fueling. The engines' ability to flow air was never the limiting factor.

Now keep in mind boost is just a measure of restriction. A stock LT4 pushing 23psi might "only" make 19-20psi with heads and a large cam.

Thanks for that! Just curious if more boost with the current setup would mean more power or just more problem to the engine and not worth the effort. I was saving the lower pulley for when I do heads/cam, but got curious as I know the 2650 need to be spun hard and currently I don't think I am spinning it hard at all. I am happy with the current power.

[JSH]

Originally Posted by KingLT1

I read a guy saying he was pushing 23psi with a 2650 on an otherwise stock LT4 with port injection and full E85. You can run more boost since you are going to have the fueling. The engines' ability to flow air was never the limiting factor.

Now keep in mind boost is just a measure of restriction. A stock LT4 pushing 23psi might "only" make 19-20psi with heads and a large cam.

I read 30# total manifold pressure, 16 boost + 14 atmosphere

[Kerry]

16 pds will not make 830 corrected with stock cam. least it did not with me. takes about 18 or 19 to make 830 to 50 and tune would need to be spot on. Thats with 11.5 to 1 compres. Yes it will make more power with more boost. I run stock cam and heads.

Think of it this way at sea level its 14.7 psi atmosphere. at 100 % efficiency then the engine is able to breath 378 ci theoretically. now add 14.7 psi boost now the engine acts as if its double the size, because it ingest double the air. Of course their are inefficiencies and variables but thats the general principle.

I have heard from many over the years that theirs a place where more boost will not make more power. Iv never been able to find that limit on even a small 1.8 liter motor even up to 60 pds just keep makeing more power. Until the crank and rods fly out lol

[Kerry]

O and im running alot of meth and it makes power on its on over 93 just like e85 only more so. has more oxygen released when combusted. somewhere in the range of 30 some % for e 48 maybe for meth and over 56% for nitro now e and meth hello

Thats how a nitro car makes 10000

[Future1LE]

Originally Posted by Kerry

16 pds will not make 830 corrected with stock cam. least it did not with me. takes about 18 or 19 to make 830 to 50 and tune would need to be spot on. Thats with 11.5 to 1 compres. Yes it will make more power with more boost. I run stock cam and heads.

Think of it this way at sea level its 14.7 psi atmosphere. at 100 % efficiency then the engine is able to breath 378 ci theoretically. now add 14.7 psi boost now the engine acts as if its double the size, because it ingest double the air. Of course their are inefficiencies and variables but thats the general principle.

I have heard from many over the years that theirs a place where more boost will not make more power. Iv never been able to find that limit on even a small 1.8 liter motor even up to 60 pds just keep makeing more power. Until the crank and rods fly out lol

Yea I can't argue against how much power I am actually making since I don't have the dyno number to back it up. Just basing the numbers on similar mods other people have and dragy time shares by other zl1 and their whp, heck I could probably only be making 750whp lol. Guess I am just curious if the car will benefit from more boost and can it hold more power. If the car is not making 800 then I am not disappointed lol as that mean I still got alot of potential left.

[laynlo15]

I'm making 707 with a 2300 Maggie and THPSI PI. Just 11 psi of boost. I'm running THPSI 9.25 with 95mm pulley. On my 16ss I went from a 2300 to a 2650 and with just a few tweaks of tuning made 85 more rwhp from the swap. Ran best of 9.83@140 with the 2300 and 9.41@147 with the 2650. I think we were making 770 with the 2300 and about 850 something on the 2650. So it's reasonable to say your probably making 780 to 800 rwhp. Considering you have long tubes and I'm running stock exhaust. You should make approximately 90 to 100 more rwhp than mine. Funny that my current car makes 707 and ran 9.80@142.96 on E65 and my 16ss with 2300 made 70 more rwhp with a built motor on race fuel and only ran 9.83. These different combos were all on the same dyno, so dynos are for tuning and mean nothing till you go to the track. If you go to a bigger lower you can reduce your upper if you choose to or you will be running more boost with your current upper. You might see 20psi if your making 16 now.

[JSH]

I really don't understand how you can make 30 lb of manifold pressure with stock pulleys, and stock heads and cam. ??

[radz28]

A couple others have posted uncorrected numbers of 800+ to the tires on the 90mm and stock long block and exhaust on E'. One of those cars that I recall was at sea level, on a typical So Cal day, if I understood correctly.

It might not be an impossibility...

[Future1LE]

Originally Posted by JSH

I really don't understand how you can make 30 lb of manifold pressure with stock pulleys, and stock heads and cam. ??

Lol beats me. I'm not an expert, just reading what HP tuner is showing on my logs and its saying I'm making 15-16 pound of boost on my current pulley set up.
If I remember correctly, my 1st round of mod was the 2650 with 90mm upper,big gulp, 103 tb and dsx aux pump. This set up also was 14-15 pound I believe, probably due to the restrictions of the stock cats. My tuner was only able to tune it on 93 pump as we ran out of high side. Then I later installed the long tube headers, port injection, dropped down to 85mm and was able to still make around the same boost of 15-16. That's where we are now. Surprise quite a bit of people so far since the car so quite with the stock cam and stock exhaust muffler.

[radz28]

absolute pressure channel?