Katech_Jason

iTrader: (19)

The Katech dyno headers are a stepped header. If Kooks made their header stepped that would be interesting.

Engine: LS7 with cam and head porting

LG peak tq: 559 ft-lbs
LG peak hp: 628 hp
Kooks peak tq: 551 ft-lbs
Kooks peak hp: 633 hp

MSURacing

iTrader: (1)

Maybe we could see a A/F ratio chart to see what the engine was seeing in that dip.

Katech_Jason

iTrader: (19)

2838 13.40 13.00
3163 12.50 12.50
3587 12.30 13.10
3999 12.70 13.10
4447 13.30 13.50
4825 13.40 13.50
5207 13.20 13.00
5591 13.30 12.90
5962 13.30 13.10
6353 13.40 13.10
6727 13.50 13.20
6946 13.80 13.10

BurnOut

iTrader: (1)

Pretty interesting. Do the Kooks have a merge collector??

Katech_Jason

iTrader: (19)

Yes, they do

BurnOut

iTrader: (1)

Hell of a deal. I assume that the primary length between the two sets is similar?? I know that the LG's are ~32" long, but I can't find any information on the Kooks.

Katech_Jason

iTrader: (19)

The Kooks are a little bit shorter

BurnOut

iTrader: (1)

Hmmm... depending on how much shorter, it seems like this test was a pretty fair comparison of 1 3/4" pipes vs. 1 7/8" pipes.

It also seems to indicate that, for the most part, the headers aren't the restriction... which leads back to something that Lou at LGM said, that the weak link is the exhaust valve/port. Makes sense to me. At this point, I have to wonder if there aren't some gains to be had by (somehow) fitting a smaller intake valve and in turn fitting a larger exhaust valve to try to get the E/I ratio closer.

I dunno... I always kinda wondered why the General would fit an intake valve almost 1/4" larger than the regular LS1 piece, then barely increase the size of the exhaust valve at all. Though I have to admit that GM has designed/built a few more engines than I have....

Billy the Great

iTrader: (2)

from what ive heard one of the reasons the intake port and valve are so huge on the ls7 is because with the c5r motor, where alot of the ls7 design comes from, they had an intake restrictor to design around and to over come that they over sized everything

TheBlurLS1

iTrader: (8)

There was a thread shoing what that looked like too, Katech might have even posted it. IIRC there were 2 holes about the size of a half-dollar piece each.

Katech_Jason

iTrader: (19)

Yes, 2 restrictors 31.8mm diameter each

MSURacing

iTrader: (1)

So you guys mean to tell me that GM had to cut back on an engine!!! What, I think you guys are crazy.

Ok, come on, all we need is an aftermarket company, cough cough, Katech, you listening, to design an exhaust port that matches the intakes flow pattern closer. This way we could get all of the power out of the LS7, as if 660 on stock heads isn't enough!!!!!

This is just funny how we now have a cam only Corvette making over 600 HP and people still need more. WHERE DOES IT END!!!!!! LOL

dinker486

msuracing, are you a friend of Dorthy?

Billy the Great

iTrader: (2)

there is only so much room to package things within a certain space, if you want ginormous intake ports then something has to give, would you rather have a nice exhaust port and smaller coolant passages would make the head alot hotter and performance would suffer, making it much more prone to detonation.

Katech_Jason

iTrader: (19)

Correction: Looking at the kooks again, they don't have a merge collector. Sorry for the confusion.

Ryne @ CMS

iTrader: (10)

do the american speed headers fit on the c6 z06, there design is similar to the kooks, but with a merge collector.

Tony Mamo @ AFR

iTrader: (13)

Actually I think they dropped the ball a little....LOL

The problem is they did everything with this head to favor the intake...they fitted it with a HUGE Int. valve and located it from the chamber wall (a good thing for less shrouding) but killed the exhaust by having to move it right against the wall to make room. Forget the bigger exhaust valve....it wouldn't even fit. To make this head "right" or better for a performance enthusiast looking to make some power, both valves would need to be moved over even though some low/midlift intake flow would ultimately suffer (but not by much). The I/E ratio if this head is simply way to skewed towards the Intake side....enough so that it is restricting the potential to make power (IMO) in light of the fact it has one of the best intake ports I have ever seen (which unfortunately is severely handicapped if you can't get the spent gases out of the way). A higher flowing exhaust would indeed show big gains in power...the motor is starving for it.

Killer piece though....One of the best things GM has done to date.

Tony M.

gun5l1ng3r

So is the only significant way to "fix" the exhaust valve to have a new casting made, or can extensive port work be done to make the exhaust port flow better?

Katech_Jason

iTrader: (19)

The fix is changing the I/E ratio. Extensive exhaust porting has not shown a significant difference.

WhiteDiamond

Jason,

Do you have some information to help us understand that dip the LG headers saw at the start of the dyno? The air/fuel ratio isn't labled as to which one is which, either.

Todd