[Clos.95]

What’s up guys!
So after getting car dynoed I realized my peak power isn’t where it is suppose to be. I’ve seen the LT1 usually makes peak power anywhere from 5800-6000 rpm.
What can be causing my car to make peak power so low and fall off sooner?

[Robby23]

Originally Posted by Clos.95

What’s up guys!
So after getting car dynoed I realized my peak power isn’t where it is suppose to be. I’ve seen the LT1 usually makes peak power anywhere from 5800-6000 rpm.
What can be causing my car to make peak power so low and fall off sooner?

your car stock? are you tuned? have you tried a different dyno?

[Clos.95]

Originally Posted by Robby23

your car stock? are you tuned? have you tried a different dyno?

I should’ve been more specific, my car Is all stock besides A Rotofab, some custom cat delete pipes, and Flex fuel tune. On the 91 octane run my peak power was 5200rpm and on E70 pass 5300rpm, my car left home with some pretty low numbers came in based lined at 365whp and tuned on E70 400whp, most of my friends who go on the same dyno dyno around 380whp stock and make that power at 5900rpm, I finally put two and two together on why my numbers were so low, I’m missing out on around 700rpm Of power

In my head it must be intake related the Car is not breathing properly to make power all the way to 6000rpm, we installed the Rotofab then and there on the dyno right before the baseline pass, I bought the Rotofab used off a friend and he forgot to give me the firewall plug, so we used the roto fab box with the stock elbow, also I did not use the traditional Rotofab filter I ended up using the biggest Green filter that could fit in the Rotofab box. I’m thinking that stupid air box combo could’ve been the issue, I should’ve just kept the stock box

[Nabush]

Originally Posted by Clos.95

I should’ve been more specific, my car Is all stock besides A Rotofab, some custom cat delete pipes, and Flex fuel tune. On the 91 octane run my peak power was 5200rpm and on E70 pass 5300rpm, my car left home with some pretty low numbers came in based lined at 365whp and tuned on E70 400whp, most of my friends who go on the same dyno dyno around 380whp stock and make that power at 5900rpm, I finally put two and two together on why my numbers were so low, I’m missing out on around 700rpm Of power

In my head it must be intake related the Car is not breathing properly to make power all the way to 6000rpm, we installed the Rotofab then and there on the dyno right before the baseline pass, I bought the Rotofab used off a friend and he forgot to give me the firewall plug, so we used the roto fab box with the stock elbow, also I did not use the traditional Rotofab filter I ended up using the biggest Green filter that could fit in the Rotofab box. I’m thinking that stupid air box combo could’ve been the issue, I should’ve just kept the stock box

How many miles do you have ? How many stuck in traffic jams ?

LT1 suffers from carbon build up on intake valves and with mileage and time, as well as town driving it robs power

My SS 1LE at 22,000 starts to have noticeable deposits, though it does not concern me now

My C7GS, while I removed the heads to do my cam, were showing little deposits at 9,000 miles, but I cleaned them at 5,000 miles with gasoline and cloth on a tool.

If you have 60,000 miles or a lot of town driving/Idle time this could come from there.

[Clos.95]

Originally Posted by Nabush

How many miles do you have ? How many stuck in traffic jams ?

LT1 suffers from carbon build up on intake valves and with mileage and time, as well as town driving it robs power

My SS 1LE at 22,000 starts to have noticeable deposits, though it does not concern me now

My C7GS, while I removed the heads to do my cam, were showing little deposits at 9,000 miles, but I cleaned them at 5,000 miles with gasoline and cloth on a tool.

If you have 60,000 miles or a lot of town driving/Idle time this could come from there.

Im at 42,000 miles now, I have been running E85 since I was at about 25,000 miles not sure if that’ll help slow down carbon build up or not.
Im not ruling out carbon build up on valves, but I’m thinking it was my odd air box combo I mentioned in my previous reply ^
I since then took off my Frankensteined Rotofab intake and put the stock box on for some warranty work and honestly feel the car pulls so much better with the factory air box, I’m thinking I should probably hop back on the dyno just to see any difference with just the stock air box

[Robby23]

Originally Posted by Clos.95

I should’ve been more specific, my car Is all stock besides A Rotofab, some custom cat delete pipes, and Flex fuel tune. On the 91 octane run my peak power was 5200rpm and on E70 pass 5300rpm, my car left home with some pretty low numbers came in based lined at 365whp and tuned on E70 400whp, most of my friends who go on the same dyno dyno around 380whp stock and make that power at 5900rpm, I finally put two and two together on why my numbers were so low, I’m missing out on around 700rpm Of power

In my head it must be intake related the Car is not breathing properly to make power all the way to 6000rpm, we installed the Rotofab then and there on the dyno right before the baseline pass, I bought the Rotofab used off a friend and he forgot to give me the firewall plug, so we used the roto fab box with the stock elbow, also I did not use the traditional Rotofab filter I ended up using the biggest Green filter that could fit in the Rotofab box. I’m thinking that stupid air box combo could’ve been the issue, I should’ve just kept the stock box

Would be nice to have had a baseline with the original intake to see if it was higher.

I would get your intake situated and start there since its obviously not correct. Although I don't think that would cause that much of a difference if any as long as its sealed good no leaks.

as NaBush said if you have some miles on it and no catch can carbon can build up but I myself do not know if that would cause your peak power to change that much.

I would talk to your tuner or if thats who was doing your dyno maybe get with brett with pray performance or GPI and ask them they may be able to help you or point you in a better direction.

[vtirocz]

Originally Posted by Nabush

How many miles do you have ? How many stuck in traffic jams ?

LT1 suffers from carbon build up on intake valves and with mileage and time, as well as town driving it robs power

My SS 1LE at 22,000 starts to have noticeable deposits, though it does not concern me now

My C7GS, while I removed the heads to do my cam, were showing little deposits at 9,000 miles, but I cleaned them at 5,000 miles with gasoline and cloth on a tool.

If you have 60,000 miles or a lot of town driving/Idle time this could come from there.

Regarding possible performance degradation over time, I'd just like to point out that Car and Driver's long term 40k mile 2016 Camaro SS showed no signs of degradation. The acceleration times are identical between 'new' (after initial break-in) and 40k miles.

Link: https://www.caranddriver.com/reviews...m-test-review/

Acceleration Data:

[Nabush]

I can just tell you that at some point this carbon build up on the intake valves will start to affect flow/performance. When ? This I don't know.

It is noticeable visually at 22,000 miles and I don't drive in traffic. I'm assuming people spending a lot of time at idle will build up more... Though it could be the contrary. But to me high sustained loads like roadcourse/hillclimb would run the valves hotter and burn deposits ? Idk...

Pcv system has also to work right...

[Clos.95]

Originally Posted by Robby23

Would be nice to have had a baseline with the original intake to see if it was higher.

I would get your intake situated and start there since its obviously not correct. Although I don't think that would cause that much of a difference if any as long as its sealed good no leaks.

as NaBush said if you have some miles on it and no catch can carbon can build up but I myself do not know if that would cause your peak power to change that much.

I would talk to your tuner or if thats who was doing your dyno maybe get with brett with pray performance or GPI and ask them they may be able to help you or point you in a better direction.

I’m probably going to contact my tuner and see if we can get her on the dyno with the stock Air box soon, since then I have the full Rotofab System with the Dry filter ready to go on and I’m waiting on pray performance ported TB and Intake should be here any day now. Hopefully that’ll take care of the problem if it is a breathing related problem

[Clos.95]

Originally Posted by vtirocz

Regarding possible performance degradation over time, I'd just like to point out that Car and Driver's long term 40k mile 2016 Camaro SS showed no signs of degradation. The acceleration times are identical between 'new' (after initial break-in) and 40k miles.

Link: https://www.caranddriver.com/reviews...m-test-review/

Acceleration Data:

Thanks for this info makes me feel a little better about the whole carbon build up I’m at 42,000 miles, was worried thinking I was going to have to remove heads and clean valves

[cmitchell17]

I never can figure out how the carbon buildup dosent impede flow. For what its worth, I think its a credible source, Tadge Juetcher who is the Corvette chief engineer has made statements indicating GM's long term testing they did with the LT1. He says that there is no indication of a performance degradation from carbon buildup impeding airflow.

I know its hard for me to believe too, especially when you realize how a little a change in geometry from porting can effect head flow but then how dosent a big chunk of carbon not.

[Juiced1]

Did you tune the car at all? I wonder if the airbox affected the stock tune in a negative way. You might be running super rich as the factory tune is already very rich.

[Umbriel]

Could you possibly post the dyno sheet? I know I one time had a dyno sheet where the values didn't match up right on the sides and bottom and it caused everything to be skewed off from what it should be.

[s346k]

Originally Posted by Umbriel

Could you possibly post the dyno sheet? I know I one time had a dyno sheet where the values didn't match up right on the sides and bottom and it caused everything to be skewed off from what it should be.

my guess, as well.