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General durability question about the L26 vs L67 for Gen 5.

rmcardle3

rmcardle3

New member
I have wanted to get up to speed on the subject of Gen 5 top swap-ability. So in my reading, the subject of short block health or getting a durable replacement/short block naturally came up. In 8 threads L26 was identified/mentioned as a durable alternative to the L67, for a concurrent Gen 5 (MOD) on 2 occasions. This gave me the idea for a new thread to help me understand why L26 has risen to the occasion, to sit under forced air induction, in the good company of L67 (GTP/Eaton M90 Gen 3), L32 (GTP/Eaton M90 Gen 5) and last (but definitely NOT LEAST) LC2 (GNX/Garret GT35R).

This thread’s purpose is not to question the wisdom of using the L26 as a foundation for the Generation 5 M90 Supercharger, but to understand “what is going on with the L26 that allows its non-hardened piston's to "rise the occasion"?

I thought "Forged" & "lower compression ratio” (i.e. 8.5:1) aspects of pistons go together (hand-in-hand) and that these 2 things were inseparable, at least in the context of “3.8/231 & 3800 V6” & GNX, forced induction systems, like L67 & L32.

Isn't the L26 (I know the arms are substantially improved) using pistons that are still lacking in the “forged /hardened & lower compression ratio” department, at 9.4:1? EVEN WITH "the stronger powdered metal sinter forged connecting rods"? I guess I would have thought that this made the L26 substantially limited in its application to our "forced air induction" applications, here due in part to the "weakest link" theory. This thread’s purpose is not to question the wisdom of using the L26 as a foundation for the Generation 5 M90 Supercharger, but to understand “what is going on with the L26 that allows its non-hardened piston's to "rise the occasion"? Don’t mean to “pick nits” but is there a substantial difference in GTP piston application and GNX piston application?

I guess the “nagging” question that really wears at me is this:

“Is there a substantial difference in “piston hardness (i.e. short-block durability)” one way or the other, between the 1987 GNX (GM Production Turbo w/LC2) and my 2000 GTP (GM Production Supercharged w/L67)?

All thoughts and comments are welcomed, positive (and negative).
 
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Mail Order PCM's from them are crap.

Dyno tuning however...you really can't go wrong there unless your an idiot.
 
higher compression L36/26 = more power with less boost

also need more breathing mods to have a healthy high compression m90 build
 


You'd be surprised what a difference in CR makes when using a GenV. It's almost a nightmare on a 3.4 setup to keep the knock at bay. Even with a big cam and IS3 heads.:th_nervous:
 
I like my low compression...it's more forgivable and is perfect for mucho boosto. I don't have to worry about having it tuned everytime the weather changes because I'd be knocking...or part throttle knock with a big cam and high compression...which seems to be a big issue on these cars. Talked to Zach about it in Branson last year about it...he hated tuning it. And he was on a GenIII 3.4"

01gpgt01 said:
Pretty positive it was a l36 block
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Bio248 said:
they switched back to the l67 block for the high whp and 1/4 times.
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Yup...because the L36 couldn't take what THEY wanted to throw at it.
 
Nobody ever switched anything... Matt's drag car had a L32 in it for years... it always had it.

Zoom's twincharged car had a L36 block in it when it ran 10's on blower only, and they left it in there when it went 9's on the twincharge setup.

Alot of the "L26" blocks that people have been using are identical to L36 motors, because GM had alot of L36 stock left over (and a few manufacturing problems) they had to use in the 04's.
 


Reptile said:
You'd be surprised what a difference in CR makes when using a GenV. It's almost a nightmare on a 3.4 setup to keep the knock at bay. Even with a big cam and IS3 heads.:th_nervous:
Click to expand...

Dont really get what your saying here, Ive got a gen5 2nd L67 engine in the garage and will have an IS3 cam shortly. Why would this be hard to tune and reccomend starting with a 3.4 pulley on the Gen5? No IC either or meth. Looking to have Gen5, headers, IS3 cam, ported heads 130lb springs, E85, HPTuners, 65 lbs injectors. All said and done. Heads Im looking at getting should be at least = to or better than the IS3 heads their Mizly motorsports P/P with TI retainers oversized valves and 130lb springs. If I plan on building this with the 2nd L67 thats in the garage would be better to find a different short block?
 
darkhorizon said:
Nobody ever switched anything... Matt's drag car had a L32 in it for years... it always had it.

Zoom's twincharged car had a L36 block in it when it ran 10's on blower only, and they left it in there when it went 9's on the twincharge setup.

Alot of the "L26" blocks that people have been using are identical to L36 motors, because GM had alot of L36 stock left over (and a few manufacturing problems) they had to use in the 04's.
Click to expand...

Cool

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02GrandPrixIraqVet said:
Dont really get what your saying here, Ive got a gen5 2nd L67 engine in the garage and will have an IS3 cam shortly. Why would this be hard to tune and reccomend starting with a 3.4 pulley on the Gen5? No IC either or meth. Looking to have Gen5, headers, IS3 cam, ported heads 130lb springs, E85, HPTuners, 65 lbs injectors. All said and done. Heads Im looking at getting should be at least = to or better than the IS3 heads their Mizly motorsports P/P with TI retainers oversized valves and 130lb springs. If I plan on building this with the 2nd L67 thats in the garage would be better to find a different short block?
Click to expand...

Well I was speaking about the L26 block, which is what I have. Mine has been extremely touchy and has caused me to spend hours and hours working on my timing tables to get comfortable with driving it daily and being able to stab the throttle. I worked out all of the WOT issues, it's just the part throttle hills and valleys that drives me crazy.

One of the reasons I don't care to do mail order top swap tunes.
 
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