New heads = zero hp gain
Thread Starter
Burning Brakes
Joined: Aug 2004
Posts: 910
Likes: 0
From: Burton TX
Just to narrow down other factors, Im installing brand new, injectors, plugs, and wires. I just pulled my plugs and there are a few that dont look right. These plugs have about 200 miles on them.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Originally Posted by minytrker
Yes I comp r lifters.
I would rather not say until all this is resolved, they are a supporting vendor.
I would rather not say until all this is resolved, they are a supporting vendor.
Thread Starter
Burning Brakes
Joined: Aug 2004
Posts: 910
Likes: 0
From: Burton TX
Originally Posted by vettenuts
Check the Comp web site, the lifter preload requirements for the Comp R's is very small. I am wondering if you are not closing the valves correctly. I believe the preload is in the vicinity of 0.005" but you need to check that value with Comp. With those pushrods, you have a lot more preload.
Thread Starter
Burning Brakes
Joined: Aug 2004
Posts: 910
Likes: 0
From: Burton TX
Well I went back to a smaller injector and my car seems 100% better. Im guessing the way the injectors were spraying were not agreeing with the porting in the heads. Im going to retune it today and see how it goes, but even without the car being retuned it already runs better.
Instructor
Joined: Jan 2001
Posts: 211
Likes: 0
From: Hobe Sound Florida
Originally Posted by AU N EGL
you put new heads but did not retune your car??
Tuning is the key to performance, not bolt ons on any car.
When major bolt ons are added a new tune is a must.
Tuning is the key to performance, not bolt ons on any car.
When major bolt ons are added a new tune is a must.
Thread Starter
Burning Brakes
Joined: Aug 2004
Posts: 910
Likes: 0
From: Burton TX
Originally Posted by NoWay
Racer
Joined: Feb 2004
Posts: 455
Likes: 11
From: Roanoke VA
Originally Posted by minytrker
Well I went back to a smaller injector and my car seems 100% better. Im guessing the way the injectors were spraying were not agreeing with the porting in the heads. Im going to retune it today and see how it goes, but even without the car being retuned it already runs better.
You should go into the 'injector flow rate' table of your tuning program and increase the numbers by the percentage of increase that the new injectors flow.
The flow is calibrated according to manifold vacuum so the rate will be be different at idle than it is at WOT and everything in between, reset accordingly.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Thread Starter
Burning Brakes
Joined: Aug 2004
Posts: 910
Likes: 0
From: Burton TX
Originally Posted by billiardcue
If you are just tuning the fuel/air ratio you are not compensating for the increased injector flow rate.
You should go into the 'injector flow rate' table of your tuning program and increase the numbers by the percentage of increase that the new injectors flow.
The flow is calibrated according to manifold vacuum so the rate will be be different at idle than it is at WOT and everything in between, reset accordingly.
You should go into the 'injector flow rate' table of your tuning program and increase the numbers by the percentage of increase that the new injectors flow.
The flow is calibrated according to manifold vacuum so the rate will be be different at idle than it is at WOT and everything in between, reset accordingly.
Thread Starter
Burning Brakes
Joined: Aug 2004
Posts: 910
Likes: 0
From: Burton TX
Well went to the dyno with poor results. I made 1 more hp and 1 more ft tq. The heads did nothing. I am getting great gas milage and the car runs great but heads were a rip off. I made 428/388 at the wheels. I did make 523/490 at the wheels on a 100 shot. I will post here tomorrow what vendor did these heads after talking to them again.
Thread Starter
Burning Brakes
Joined: Aug 2004
Posts: 910
Likes: 0
From: Burton TX
I pulled the heads back off. The only thing I could see is it looks like a valve seat is messed up. One valve is sunk in the seat alot futher than the rest. Im sending them back tomorrow so the vendor can go through them.
Drifting
Joined: Jan 2001
Posts: 1,347
Likes: 4
From: Slidell La
Originally Posted by BlownZ
wow, what a horror story. Keep us posted on this, hopefully the vendor will fix the problem, and you will see some good results.
Don't know how to "raise a valve" that unless you can change a hardened seat and grind to get the correct fit. Best of luck, spending $$$$ and effort with a zero return is really a bumber. Hope it works out.
vettdvr
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
I would question the overall job on the porting at this point. Were the heads flowed and balanced? I think I would seriously consider one of the budget head sets or possibly a new set of aftermarket at this point, the amount of work to install the heads again only to find out they are still not right just doesn't seem like a risk worth taking.
Burning Brakes
Joined: Mar 2003
Posts: 874
Likes: 0
From: Bonita CA
Question: Are '99 LS1 and 02' & up LS6 pushrods the same length? I recently installed new 243 heads with lightweight valves and new AFR dual springs onto my LS1 and now the motor sounds like a sewing machine. Is this normal?
Le Mans Master
Joined: Feb 2002
Posts: 5,970
Likes: 20
From: San Marcos Texas
Originally Posted by DJMRTS
Question: Are '99 LS1 and 02' & up LS6 pushrods the same length? I recently installed new 243 heads with lightweight valves and new AFR dual springs onto my LS1 and now the motor sounds like a sewing machine. Is this normal?
Last edited by chriswtx; Sep 5, 2006 at 06:28 PM.
Burning Brakes
Joined: Jun 2002
Posts: 825
Likes: 0
From: San Diego(Sabre Springs) Ca
Originally Posted by DJMRTS
Question: Are '99 LS1 and 02' & up LS6 pushrods the same length? I recently installed new 243 heads with lightweight valves and new AFR dual springs onto my LS1 and now the motor sounds like a sewing machine. Is this normal?
Don't know about the AFR springs, but I installed Comp cams 918 springs with my TR 224/224 cam. Mine sounds like a sewing machine.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
The best way to do it is buy an adjustable pushrod for $20 and measure, its the only way to ensure you have the correct preload. These engines, even with a cam, shouldn't make any noise. If they do, the preload has not been correctly set.
Burning Brakes
Joined: Mar 2003
Posts: 874
Likes: 0
From: Bonita CA
Originally Posted by chriswtx
Putting LS6 243 heads with the light weight valves on an LS1 requires a shorter pushrod...The valve stems on the light weight valves are longer than the standard LS1 valve. GM got away with this by still using the 7.4" pushrod but making the base circle of the stock Z06 cam smaller..