KLLRVET

April 2010, my car dropped a valve, and totally destroyed the motor.

April 2011, my new motor was completed and installed in my car.

http://forums.corvetteforum.com/c6-z...l-up-deth.html


The combo was as follows:

Stock milled heads .030
Bronze exhaust guides
Solid stainless Ferrea exhaust valves
Ragin Racin punisher cam and complimenting springs
Smith brothers 3/8 pushrods
Morel link bar lifters
Mahle 11.5:1 forged pistons (lighter that the stock ones BTW)
Arp head bolts
Arp 2000 rod bolts
Stock rods reconditioned by Crower
Aviad trap door oil pan insert
Lingenfelter zr1 twin disk clutch
Tick master cylinder
Ported throttle body by Jeremy Formato
Vararam intake
LG 1 3/4 headers
Modded stock mufflers
Yella Terra roller rockers

This combo netted me a respectful 539 rwhp/499 rwtq. I was happy with it, and yet a bit disappointed. I always thought I was 15-20 rwhp down with the 1 3/4 headers VS having 1 7/8 headers. I really wanted at least 550 rwhp, so I had a BAD case of header envy.

A couple of months ago, I started a thread about a power dip that I had at about 2500 rpm:
http://forums.corvetteforum.com/c6-z...isher-cam.html

Not long after the thread was posted, I got a call from Louis, at LG Motorsports. He called to help me understand why there was a dip in power, discussing overlap, intake runner length, and header primary tube length. During our conversation, I of course mentioned my header envy. Louis offered to send me a set of their 1 7/8 headers to try out.

I was so excited, when I got them! I couldn't wait to unlock the power I was missing out on!!! After spending a few days installing them in my garage, I took the car out...untuned BTW. It was a different animal...but not exactly what I expected. My car used to wheel spin so hard at WOT in 2nd gear, it tried to swap ends! With the 1 7/8 headers, ..... there was NO wheel spin in 2nd gear. The car was noticeably slower.....
I called Louis to tell him what I had experienced. It wasn't to complain, but to just to share what I had found. He told me that he wasn't surprised at all, as LG Motorsports had found that 1 7/8 headers really weren't needed until the motor exceeded 440CI.

Here is what the dyno showed after tuning:





To make sure we were comparing apples to apples weather wise, here are the conditions of those runs:



There was a considerable loss in low end power, and no gain in top end. Hmmmmm.... so much for my header envy.....

Tony

KLLRVET

This dyno makes a point I had been wondering about. The LG 1 3/4 have very LONG primary lengths (32 inches IIRC). The LG and the American Racing 1 7/8 headers have considerably shorter primary lengths. I believe(and my be wrong), that is the reason there car lost power down low.

It appears that the stainless works 1 7/8" and 2" headers have 31 inch primaries. I think that may be why they look good on your dyno chart.

I really want to test a set of longer 1 7/8 headers.

Tony

FNBADAZ06

Very interesting. This hasn't been the first time I've heard of the torque drop after installing longtubes, but it's usually on a stock car.
I have B&B 1 7/8 headers for my car that haven't been installed yet...I wanted headers more for the sound than the power boost, but it will be interesting to see what my dyno chart reads after my install and tune.

Thanks for posting this up

nrt69

what caused your car to drop a valve?

KLLRVET

The exhaust valve broke at the tulip. Do a search, there is a LOT of heated debates about dropped valves and the causes.

lane_change

I would think that your setup would make more power with the milled heads and the Punisher cam shaft regardless of the header configuration.

I know I had the LG 1 3/4" headers on my cam only Z06 and made 545/505 with the QM Black Mamba and I blamed my lower power numbers on the headers as well....but I loved the low end grunt of the smaller diameter headers. Unlike you I switched a lot in my setup when I went to the 1 7/8" headers so I can't claim any difference from just the headers, but I had read lots about people switching to a 2" header for my setup and making a big improvement, so I had 2" header envy. Pretty conclusive evidence, except the new motor may not be as well broken in as your old motor so maybe you will get some more power out of her as time moves on.

KLLRVET

Nothing new about the motor. The motor with the 1 3/4 and the motor with the 1 7/8 are the same motor. My motor was broken in on the dyno on day one, per the procedure I requested (insisted on)

lane_change

Time to try out a 2" set of headers and let me know.

KLLRVET

If a manufacturer wants to donate a set for testing, I'd be glad to post the results

Captain Z

Off topic, but what's your explanation for the high oil pressure at idle? I noticed this in video. Does it go over 100 at higher rpm/wot and do you think this is a problem?

I'm asking because I also have a build motor and high oil pressures. At idle my car sees around 59-60 psi. At 6-7k it will push 110psi and then return to 60 at idle.

I've heard from many others that high oil pressures simply rob the motor of additional horsepower; maybe something worth considering

thanks.

Nice build by the way

KLLRVET

I shimmed the oil pump bypass spring. Cold idle I'm 75ish psi, 150 degree oil temp I'm 60ish. I haven't been able to watch the pressure real close at high rpm, but I believe it approaches 100 psi. I'm sure some power is lost there.

lane_change

I also have a built motor that makes very high oil pressure...55-60psi at idle and 100+ at WOT. I talked to the builder and he did not see anything wrong with that, his words were that he's never seen a motor let go due to too much oil pressure. I talked with Quality Motorsports about this as well and was told a similar thing about having high oil pressure...not sure if it robs any hp and if so how much, but both shops I spoke with seemed fine with my oil pressure levels.

LEAVINU

Interesting results. I too have contemplated 7/8 headers but after this post..... hmmmm.. not so much.

Geared

.....leave the fast 102 on that you mention in the other thread.....then put the 1 3/4 on...and report. My guess is you will make less power across the board with the 1 3/4 + 102 versus the 1 7/8 + 102......More air in = more air out.

just a thought

KLLRVET

you could be right. Soon enough we will all know.

Tony

BigV

Which version of the LG headers did you installed for both 1 3/4 and 1 7/8? Super Pros?

KLLRVET

Yes, the super pros

Captain Z

Good info. Thanks for letting me know. I guess the built motors have a lot tighter tolerances than a stock ls7.

Going with the punisher cam myself after a much bigger cam tore up my stock rocker arms. Rebuilding with Crower shaft mounted rockers...may go the solid roller route...now would be the time with everything apart!!!

Any thoughts on performance gains?!

Off topic again...sorry...should make a new thread

z06tx

Hmmm - I was debating swapping out my 1 3/4 LG's for the 1 7/8. Not sure now.

LME has my motor now but when put back together it will have the nw102tb and fast intake with the 1 3/4 headers. Also with milled heads and big cam so I'm curious what will turn on the dyno.

Thanks for the info!
//art

KLLRVET

I've been happy with the power of the Punisher, I just dont like to lope and chop, to me, a Z06 is too modern, too refined for a big cam. It is however, a neccesary evil if you want to make the power. With that, Im pleased with the Punisher. I like the power it makes everywhere.