l92's on a lq4

[Shon]

Originally Posted by pharmd

Yeah, didn't he tear something up in the drivetrain before he got to maximize the combo? He had the Ed Curtis flowtech cam right?

Not jeff's he sold it in perfect condition, the new owner didnt make wise decisions but it still have FTI cam and AI heads but alot more displacement....and car is for sale...

[pharmd]

Ahh, ok...I noticed he no longer had it...didn't know what happened to the car after he sold it. I have heard the "GM went with these heads, so obviously they know what they are doing" before...and especially considering that they use these on trucks and heavy SUV's...I can certainly see where folks would have that belief...but at least to this point, we really havent see the L92's pay off in terms of ET/MPH performance (sorry VA Speed LOL)...at least as far as I can tell (dyno #'s don't win races).

[68GMCCustom]

Its all interesting to hear and listen to...and my guess is most folks would side with whatever type heads they are running. I've got a 243 headed 6.0L LS2 in my TBSS that came that way...and bought a new 6.0L LY6 because it (came that way) had the L92/LS3 style heads and I see them making more power. The TBSS is still under warranty and since its had trans issues I prefer to leave it that way until out of warranty and paid off...then its time to increase the performance on it. Until then...I'll be making what I can out of the LY6...and my guess is, it just might be surprising some folks? Or at least...hopefully the guy in the other lane!

[matthew20061]

Originally Posted by 68GMCCustom

Its all interesting to hear and listen to...and my guess is most folks would side with whatever type heads they are running. I've got a 243 headed 6.0L LS2 in my TBSS that came that way...and bought a new 6.0L LY6 because it (came that way) had the L92/LS3 style heads and I see them making more power. The TBSS is still under warranty and since its had trans issues I prefer to leave it that way until out of warranty and paid off...then its time to increase the performance on it. Until then...I'll be making what I can out of the LY6...and my guess is, it just might be surprising some folks? Or at least...hopefully the guy in the other lane!

Haha, I guarantee it will be surprising some folks!

[pharmd]

Originally Posted by 68GMCCustom

Its all interesting to hear and listen to...and my guess is most folks would side with whatever type heads they are running. I've got a 243 headed 6.0L LS2 in my TBSS that came that way...and bought a new 6.0L LY6 because it (came that way) had the L92/LS3 style heads and I see them making more power. The TBSS is still under warranty and since its had trans issues I prefer to leave it that way until out of warranty and paid off...then its time to increase the performance on it. Until then...I'll be making what I can out of the LY6...and my guess is, it just might be surprising some folks? Or at least...hopefully the guy in the other lane!

Check my sig...there are alot of folks over on TBSS owners that have 6.0 and larger ci motors running "BOTH" L92 and cathedral port heads...you will get some insight into results of both castings. My motor is low compression, set up for boost right now, and I'm running a conservative cam and turbo stall (2800), and the stock intake (no porting), yet my AI 243's helped me to become the fastest all motor AWD TBSS (i'm full weight btw). From what I have seen, the L92's are hit and miss on the TBSS on stock cubes. There was one guy that ran 12.29 with them...I believe he was the fastest. Running well with those heads has EVERYTHING to do with proper cam selection...you CANNOT use cathedral port style cam specs and expect it to do well on L92 heads, I think that is a big part of why so many folks don't run well with those castings. But the major thought, "port velocity" so important for TQ and overall responsiveness on the hwy (and to some degree at the track)...the smaller casting, even if it doesn't necessarily match the peak flow #'s, if designed well and velocity is good, its gonna likely perform more acceptibly on a street driven vehicle over the larger port head. $0.02

[68GMCCustom]

well my truck is quite a bit lighter then our TBSS...not sure I would change the heads on it either....just throw a intercooled maggie on it, replace trans with a beefier unit (6L80e would be nice) and add trans cooling, and open up the exhaust system. And I can see where a normally aspirated 6.0L on a heavy TBSS might do better with the smaller ports and then it would the L92's larger ports.

And as far as my cam choice goes.....for sure you can't just throw just any cam in a L92/LS3 headed motor. IMHO Comp rates their cams (and springs) strange somtimes anyway. They show this cam as a catherdral port cam. Truth is, I planned to by MTI Racings Stage I cam...but found I could get 20% off the Comp cam LSr version when I was ready to buy making it like $80 cheaper, for a cam with the same duration and lift specs. MTI Racing Stage 1 Camshaft Specs are: 223/231 .610/.617 (they won't give more info) and its in their LSX line and specifically engineered for the L99 Camaro. Truth is my cam guy that spec'd it for me wanted me to go a bit bigger and I'm sure I will...but you have to start out somewhere right? And since the goal has always been 11's (but secretly hoping for better w/o caging it yet) and still drive it home....I'm sure I'll be making other changes to get there and run consistently.

[pharmd]

Originally Posted by 68GMCCustom

well my truck is quite a bit lighter then our TBSS...not sure I would change the heads on it either....just throw a intercooled maggie on it, replace trans with a beefier unit (6L80e would be nice) and add trans cooling, and open up the exhaust system. And I can see where a normally aspirated 6.0L on a heavy TBSS might do better with the smaller ports and then it would the L92's larger ports.

And as far as my cam choice goes.....for sure you can't just throw just any cam in a L92/LS3 headed motor. IMHO Comp rates their cams (and springs) strange somtimes anyway. They show this cam as a catherdral port cam. Truth is, I planned to by MTI Racings Stage I cam...but found I could get 20% off the Comp cam LSr version when I was ready to buy making it like $80 cheaper, for a cam with the same duration and lift specs. MTI Racing Stage 1 Camshaft Specs are: 223/231 .610/.617 (they won't give more info) and its in their LSX line and specifically engineered for the L99 Camaro. Truth is my cam guy that spec'd it for me wanted me to go a bit bigger and I'm sure I will...but you have to start out somewhere right? And since the goal has always been 11's (but secretly hoping for better w/o caging it yet) and still drive it home....I'm sure I'll be making other changes to get there and run consistently.

6L80 woulda been perfect had they put it in the TBSS...I used to have Jeep SRT8, with the 5 sp auto, and even the extra gear there was VERY noticable. There is a guy on TBSSowners working on a retro fit kit for the 6L80...to me, whether it be a 60's truck or a newish tbss, that is a great tranny to go with.

[matchstick]

I have to agree with Shon and Pharmd on the L92's. They flow well and make good numbers but they have a lot bigger runners. A good cathedral port head that's less cc's and flows the same will make more power. It takes a big cam and some cubic inches to make the L92's shine. I had a set when they first came out that flowed 375 on the intake and 285 on the exhaust. I about fell over when I cc'd the runners and they were 260 cc's.
If I already had a set on a engine I'd go ahead and roll with it, but be careful on cam selection.