LT1-LT4 Modifications - How high to spin turboed 383?

Forged 9.2 compression 383 with a TC78.

Cam-224/224 .577/.582 114 LSA
Rockers-crower 1.65
Springs-Comp 26094-16. Seat load: 178lbs @1.900''_Open load: 459lbs @1.275_Rate: 449lbs/in
Lifters-LS7 with about .00416" preload

Currently only spinning to 6000, but would like to turn it up a little. I'm making 600hp and 600ft/lbs spinning to 6000.

What should this valvetrain be good to? I've got the 24X conversion so the stock computer is no longer the limiting factor.

whens your cam stop making power?

I don't know. I was hoping someone with something similar would chime in. Here is the dyno sheet, but I think we had the rev limiter set to low.

http://i61.photobucket.com/albums/h77/LT1_POWR/Camaro%20turbo%20build/pics.jpg

I don't know. I was hoping someone with something similar would chime in. Here is the dyno sheet, but I think we had the rev limiter set to low.

http://i61.photobucket.com/albums/h77/LT1_POWR/Camaro%20turbo%20build/pics.jpg

idk from your dyno it wouldnt do any better to spin it any higher than 6000 it stops at 6200, put a bigger cam in it if you wanna spin higher

The graph is deceiving. The motor hit the rev limiter, thats why it dropped off like that and then bounced back up.

The graph is deceiving. The motor hit the rev limiter, thats why it dropped off like that and then bounced back up.

its awesome number... I spin mine to 6700 idk why your rev limiter is already adjusted

Why spin more rpm? Just turn up the boost for more power

You should spin high enough to use the whole top of the power curve. By shifting just after peak power you endup further down the curve after the shift than necessary.

I don't have any boost experience but with an NA setup with a good valvetrain it is typical to turn 4-500rpm past peak

powers still going up keep twisting it........if it will go there and not scatter of course......if you plot your shift extention from high to low rpm the line should be straight horizontal on the graph......plot it and thats how high you rev it

On your cubic inch with that cam... I'd say true peak power is somewhere between 5800-6000rpm, so like other's said, shift between 6200-6400rpm.

Spinning higher will not make more power though. Only way to do that is to turn up the boost as it sits, or swap out the turbine housing for a bigger one.

I run my set up to 6800rpm and the motor still wanted more. But im limited to the stock pcm right now. I would twist it up untill i was no longer making power and adjust the limiter to the results you get.

I run my set up to 6800rpm and the motor still wanted more. But im limited to the stock pcm right now. I would twist it up untill i was no longer making power and adjust the limiter to the results you get.

That's the plan. Anyone know if/when I'll encounter problems with valve float or anything else.

......if you plot your shift extention from high to low rpm the line should be straight horizontal on the graph......plot it and thats how high you rev it
Exactly. Very few people seem to understand that.
My power peak is at 6400 and I shift at 7000-7100 because the (relatively) tight converter pulls it down to 5400 on the shifts.

On a boosted setup u can makes huge power and still keep the rpms below 6500. Just add more boost. Sooner.

with a boosted car they make a lot of power below peak so even if you short shift it. your not likely to lose much et. if you say drop 1k rpm at each shift point you would only drop 50 hp. realistically you will drop less than 750 rpm depending on the trans and convertor.

with a boosted car they make a lot of power below peak so even if you short shift it. your not likely to lose much et. if you say drop 1k rpm at each shift point you would only drop 50 hp. realistically you will drop less than 750 rpm depending on the trans and convertor.

You're also losing the mechanical advantage from gearing which is the bigger factor.

Looks like your building max boost at 3500 rpm.

Obviously your cam wants more RPM as its still climbing.

The whole point isn't to make more power, that'll come in a couple weeks when I turn the boost up. It's to find the power that's already there. I just want to see what kind of power can be made with only 10psi.

What heads do you have?

Brodix Track 1. They flow over 330cfm.

Brodix Track 1. They flow over 330cfm.

Did you have work done to them? I am seeing only 276 at .700 lift out at the box and a full CNC is 326.

Since your cam isn't even lifting to .700 its more like .600 you can only flow 276 stock, and 319 CNC'd. Which are still great numbers.

At 10psi a 383 spinning at 6000rpm would need 949cfm.
Spinning 7000 (LT1 PCM Limit) would need 1107cfm.

CNC'd but not by Brodix:twisted:. They flow over 330. Also I'm using the 24X LS1 style ignition and PCM.

At .700? Cause you need a higher lift cam to really see those heads potential, eh its Force Induction anyways so it doesn't matter to much.

If you are using a 24x system, spin that bitch to the moon.

I think its at upper 320's at .600 and low 330's at .650. I don't know why Lloyd went with such a small cam, if I put in another cam, it would be quite a bit bigger since the turbo tames it a little.

I think its at upper 320's at .600 and low 330's at .650. I don't know why Lloyd went with such a small cam, if I put in another cam, it would be quite a bit bigger since the turbo tames it a little.

When its FI it doesn't need a super large cam, because air is being forced into the cylinders unlike NA where its using a vacuum.

So the cam is a pretty good choice, will save wear and tear on the valvetrain.

But on his .579/.578 cam its go for 6400rpm. So you need to spin it a bit more and will see some more power.

AI .576/.580 says between 6500 - 6700rpm.

When its FI it doesn't need a super large cam, because air is being forced into the cylinders unlike NA where its using a vacuum.

I just want more lope at idle. Its a great cam, just doesn't have enough thump. I've got the idle set to as low as it'll go without dieing and you can't really even tell it has a cam.

I plan on spinning it to about 7000 on the dyno, just to see if it still makes power up there. I might not necessarily spin it that high on the street though.

I just want more lope at idle. Its a great cam, just doesn't have enough thump. I've got the idle set to as low as it'll go without dieing and you can't really even tell it has a cam.

Lope in the idle comes from the overlap. Overlap is bad in a FI setup. Why? Overlap in a NA set up creates scavenging and as the exhaust gases are leaving the cylinder at a fast rate it creates a vacuum. By opening the intake valve at the same time that vacuum helps suck more fresh air in, filling the cylinder better than just the intake valve open, exhaust closed could.

Well when you have a turbo you are back pressure to the system, since the exhaust gas has to spin the turbo. So if you have enough back pressure the exhaust gas will flow backwards. This is bad on a turbo.