ls7 434ci low power!!!
You're really saying that 1 7/8" header is costing 20hp
Thread Starter
Staging Lane
Joined: Nov 2009
Posts: 91
Likes: 0
Seems like everything pretty much checks out sahwan....here is my assessment below:
I believe that your cam isn't a good match for your cylinder heads and compression ratio. Personally I would like to see more intake duration and a split of about 15 degrees with the exhaust, more lift and a tighter LSA. I think you could easily pick up 30-40 more HP with a better cam when combined with the exhaust system below. Next, your headers are too big, the 2" primary is likely costing you 12-15HP over a good 1-7/8" header and preferably a stepped 1-7/8" to 2" header. If you got a stepped 1-7/8" header and specified a 3-1/2" merge collector with 3-1/2" head pipes you likely would pick up an additional 25-30HP over your current exhaust system.
I agree with Tony that your intake system is likely begging for an additional 20HP with his trick ported manifold.
Add these up:
Cam: 30-40HP
Exhaust: 25-30HP
Intake: 20HP
You're looking at an opportunity of 75-90RWHP which would put you in the 670-685 range!
I believe that your cam isn't a good match for your cylinder heads and compression ratio. Personally I would like to see more intake duration and a split of about 15 degrees with the exhaust, more lift and a tighter LSA. I think you could easily pick up 30-40 more HP with a better cam when combined with the exhaust system below. Next, your headers are too big, the 2" primary is likely costing you 12-15HP over a good 1-7/8" header and preferably a stepped 1-7/8" to 2" header. If you got a stepped 1-7/8" header and specified a 3-1/2" merge collector with 3-1/2" head pipes you likely would pick up an additional 25-30HP over your current exhaust system.
I agree with Tony that your intake system is likely begging for an additional 20HP with his trick ported manifold.
Add these up:
Cam: 30-40HP
Exhaust: 25-30HP
Intake: 20HP
You're looking at an opportunity of 75-90RWHP which would put you in the 670-685 range!
Thanks for helping me
About the camshaft Who would you recommend for custom camshaft or do you have a camshaft spec
I will try to change the headers and the intake manifold , but they told me you need 2 inch headers because you have a high compression engine 😅😅
Leave the headers. The length of the primary might be costing you a little but you will not see 15 hp in smaller headers. I would want the primary length to be 31-32" dia is fine tuning but not worth spending $1000.
My 454 had 2 to 2.125 with 3.5 merge. Played with length and found a little top end et.
Tim
My 454 had 2 to 2.125 with 3.5 merge. Played with length and found a little top end et.
Tim
Thanks for helping me
About the camshaft Who would you recommend for custom camshaft or do you have a camshaft spec
About the camshaft Who would you recommend for custom camshaft or do you have a camshaft spec
I will try to change the headers and the intake manifold , but they told me you need 2 inch headers because you have a high compression engine
Leave the headers. The length of the primary might be costing you a little but you will not see 15 hp in smaller headers. I would want the primary length to be 31-32" dia
You changed 3 things when you swapped headers.
And for those that don't believe installing the "wrong" size header can cost you power here is an excerpt from an unsolicited e-mail that I received from a fellow enthusiast a while back who swapped 1-3/4" headers on a 434" motor for 2" headers and I quote from the e-mail
I installed the 2"ers first 2 weeks ago. When we installed them I LOST 25/30!!!
As we all know (or should know), it's all about maximizing the combination, not just selecting individual component pieces and hoping for the best.
The lifters can be the problem.... I've been told over and over the LS7 lifters can rob a couple horsepower in the high rpm range which sounds like is happening to you.
On another note dynos are just for tuning and at 590 plus at the tire I'll Boston
e more interested in seeing your trap speed at the track. It tells the real story. You have a respectable number at the tire there. That's roughly 700 horse at the crank!! Some larger 454 LsX motors don't even make that.
On another note dynos are just for tuning and at 590 plus at the tire I'll Boston
e more interested in seeing your trap speed at the track. It tells the real story. You have a respectable number at the tire there. That's roughly 700 horse at the crank!! Some larger 454 LsX motors don't even make that.
Pretty sure Jared went 8.82 with stock Ls7s. Who did the cam?
Teching In
Joined: May 2014
Posts: 49
Likes: 0
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حياك سهوان
I would go with custom camshaft that will give you an optimal DCR to make more power with Q16.
If the cam that is already installed is one of these (off the shelf), then that's your problem. I think those cams were grinded to be used with 11~12 SCR and give you power for pump gas DCR.
I would go with custom camshaft that will give you an optimal DCR to make more power with Q16.
If the cam that is already installed is one of these (off the shelf), then that's your problem. I think those cams were grinded to be used with 11~12 SCR and give you power for pump gas DCR.
The exhaust opening event on that camshaft is no where near early enough for a 434 with 14:1 compression.
IVC is a bit early, but the EVO event is killing a ton of power. It could use a bit more overlap too IMO.
When you have such high compression you are applying MUCH more leverage to the piston early on in the power stroke. A high compression engine puts much more work to the piston in fewer crank degrees than a low compression engine. A high compression engine also drops cylinder pressure faster than a low compression engine.
This necessitates a much earlier opening exhaust event to utilize the additional cylinder pressure instead of waiting later to open the exhaust valve and robbing top end HP.
There could possibly be something going on in the valve train at high engine speed based on how the graph looks a bit wavy, but that could also be timing and fueling causing that.
It could have a valve control issue, but normally it shows up in greater fashion than seen on this graph.
I can say this though, the EVO event on that cam is at least 10 degrees too late.
IVC is a bit early, but the EVO event is killing a ton of power. It could use a bit more overlap too IMO.
When you have such high compression you are applying MUCH more leverage to the piston early on in the power stroke. A high compression engine puts much more work to the piston in fewer crank degrees than a low compression engine. A high compression engine also drops cylinder pressure faster than a low compression engine.
This necessitates a much earlier opening exhaust event to utilize the additional cylinder pressure instead of waiting later to open the exhaust valve and robbing top end HP.
There could possibly be something going on in the valve train at high engine speed based on how the graph looks a bit wavy, but that could also be timing and fueling causing that.
It could have a valve control issue, but normally it shows up in greater fashion than seen on this graph.
I can say this though, the EVO event on that cam is at least 10 degrees too late.
Launching!
Joined: Apr 2005
Posts: 229
Likes: 3
From: Frisco TX
Seems like everything pretty much checks out sahwan....here is my assessment below:
I believe that your cam isn't a good match for your cylinder heads and compression ratio. Personally I would like to see more intake duration and a split of about 15 degrees with the exhaust, more lift and a tighter LSA. I think you could easily pick up 30-40 more HP with a better cam when combined with the exhaust system below. Next, your headers are too big, the 2" primary is likely costing you 12-15HP over a good 1-7/8" header and preferably a stepped 1-7/8" to 2" header. If you got a stepped 1-7/8" header and specified a 3-1/2" merge collector with 3-1/2" head pipes you likely would pick up an additional 25-30HP over your current exhaust system.
I agree with Tony that your intake system is likely begging for an additional 20HP with his trick ported manifold.
Add these up:
Cam: 30-40HP
Exhaust: 25-30HP
Intake: 20HP
You're looking at an opportunity of 75-90RWHP which would put you in the 670-685 range!
I believe that your cam isn't a good match for your cylinder heads and compression ratio. Personally I would like to see more intake duration and a split of about 15 degrees with the exhaust, more lift and a tighter LSA. I think you could easily pick up 30-40 more HP with a better cam when combined with the exhaust system below. Next, your headers are too big, the 2" primary is likely costing you 12-15HP over a good 1-7/8" header and preferably a stepped 1-7/8" to 2" header. If you got a stepped 1-7/8" header and specified a 3-1/2" merge collector with 3-1/2" head pipes you likely would pick up an additional 25-30HP over your current exhaust system.
I agree with Tony that your intake system is likely begging for an additional 20HP with his trick ported manifold.
Add these up:
Cam: 30-40HP
Exhaust: 25-30HP
Intake: 20HP
You're looking at an opportunity of 75-90RWHP which would put you in the 670-685 range!
Launching!
Joined: Apr 2005
Posts: 229
Likes: 3
From: Frisco TX
And when I suggested changing headers to sahwan I wasn't proposing only a header swap either! It was adding a good larger merge collector, larger exhaust pipe and an X.......I've been designing and building custom high performance exhaust systems with proven results for over 30 years so I really do know a thing or two about exhaust systems.....
And for those that don't believe installing the "wrong" size header can cost you power here is an excerpt from an unsolicited e-mail that I received from a fellow enthusiast a while back who swapped 1-3/4" headers on a 434" motor for 2" headers and I quote from the e-mail this person lost 25 RWHP and 30 RWTQ!
As we all know (or should know), it's all about maximizing the combination, not just selecting individual component pieces and hoping for the best.
And for those that don't believe installing the "wrong" size header can cost you power here is an excerpt from an unsolicited e-mail that I received from a fellow enthusiast a while back who swapped 1-3/4" headers on a 434" motor for 2" headers and I quote from the e-mail this person lost 25 RWHP and 30 RWTQ!
As we all know (or should know), it's all about maximizing the combination, not just selecting individual component pieces and hoping for the best.
Launching!
Joined: Apr 2005
Posts: 229
Likes: 3
From: Frisco TX