Is Gen III hardware that bad?
Thread Starter
Teching In
Joined: Feb 2008
Posts: 31
Likes: 8
From: NJ
Is Gen III hardware that bad? I have an LS1 GTO with a H/C/I 346 and TH400 combo, car has a 5400 stall and is set up for drag racing. It's a bracket car and I'm working with somewhat of a budget. I'm considering building a 383 with top notch heads (Black Label, TEA or Trickflow) and a single plane intake. I've talked to a few people that say it would be much, much better to go to a 4"+ bore from an LS2 or 3. I want to stay with an aluminum block since conserving weight is a major concern with a car that's so heavy to start with. The car has been 10.98 with the current combo, is a 383 with improved heads and a single plane really going to wake it up? People make it sound like Gen III is the oldest tech in the world, but there still seem to be a ton of fast LS1/6 motors running around
Gen III stuff isn't BAD but it is at a disadvantage when it comes to bore size and the resulting head availability.
If you're spending the same amount of $$ on a stroker kit, heads, etc., why not open yourself up to the possibility of spending a little more on a LS2 or LS3 block? The same spend on a stroker kit then gets you 400+ inches. Also allows LS3-type heads which do require a 4" bore minimum due to bigger valves.
If you'll spend for black label heads, why not a LS3 block for another $1000 and your stroker is now a 416 instead of a 383? To a certain extent also, bigger bore allows most heads to flow better.
FWIW, the stock LS3 heads flow more than most ported cathedral heads. The aftermarket has done some amazing things with the cath heads but still the max effort cath stuff is not that much ahead of the stock heads running around in grandpa's 6.2L Silverado.
If you're spending the same amount of $$ on a stroker kit, heads, etc., why not open yourself up to the possibility of spending a little more on a LS2 or LS3 block? The same spend on a stroker kit then gets you 400+ inches. Also allows LS3-type heads which do require a 4" bore minimum due to bigger valves.
If you'll spend for black label heads, why not a LS3 block for another $1000 and your stroker is now a 416 instead of a 383? To a certain extent also, bigger bore allows most heads to flow better.
FWIW, the stock LS3 heads flow more than most ported cathedral heads. The aftermarket has done some amazing things with the cath heads but still the max effort cath stuff is not that much ahead of the stock heads running around in grandpa's 6.2L Silverado.
TECH Apprentice
Joined: Oct 2015
Posts: 310
Likes: 24
Budget to me means add some juice if your racing. 5.3 with 243 heads can get you into the 9 s anything faster than 9.99 gets into alot of extra dollars for the safety stuff.
To me if you set on a stroker about the best bang for the buck is an iron lq4 ,408. To stay all aluminum it gets spendy fast.
To me if you set on a stroker about the best bang for the buck is an iron lq4 ,408. To stay all aluminum it gets spendy fast.
Edit: here it is!
https://ls1tech.com/forums/parts-cla...-2006-gto.html
We can spend all of your money for you.
Staging Lane
Joined: Dec 2004
Posts: 65
Likes: 10
From: Weatherford, TX
You guys are spoiled. Olde skool oval port big block heads don't flow as well as my ported cathedrals, and those heads will make 600+ hp on a 454.
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I have an LS1 GTO with a H/C/I 346 and TH400 combo, car has a 5400 stall and is set up for drag racing. It's a bracket car and I'm working with somewhat of a budget. I'm considering building a 383 with top notch heads (Black Label, TEA or Trickflow) and a single plane intake. I've talked to a few people that say it would be much, much better to go to a 4"+ bore from an LS2 or 3. I want to stay with an aluminum block since conserving weight is a major concern with a car that's so heavy to start with. The car has been 10.98 with the current combo, is a 383 with improved heads and a single plane really going to wake it up? People make it sound like Gen III is the oldest tech in the world, but there still seem to be a ton of fast LS1/6 motors running around
LS1/Gen3 383 strokers typically do not gain much if any hp over a well done forged 347. The strokers will normally gain 25 to 45 foot pounds of torque over the forged 347. This seems to be due to the 3.9 bore size the LS1/LS6 block is limited to and the restrictive intake manifolds typically required.
Often the 3.9 bore will limit the intake valve size to about 2.04 any bigger and the valve gets shrouded and does not flow as well.
My Brian Tooley hand finished TEA LS6 Stage 2.5 from 2003 could flow about 345 cfm (2.08 valve) on a 4.125 bore, 335 on a 4.0 bore and 320 (2.04 valve) 3.9 bore.
Why give up 25 cfm of air flow and potentially 45 to 60 hp by using a 3.9 bore?
I'm sure TEA's newer heads are even better nearly 15 years later.
I went with a 3.9 bore LS1 383 with the TEA's mentioned above and a small cam for my street driven 91 RS Camaro but if the RS was going to be a RACE care only a 4.125 bore block or bigger would have been acceptable to me for the above reasons.
Best wishes on the build.
I wasn't always so spoiled; I was born a poor Mustang child and can remember grinding exhaust bumps out of cast iron E7TE heads on my '91 LX..That was a lot of labor for a handful of horsepower. Probably flowed a whopping 160CFM when I was done!
You guys are spoiled. Olde skool oval port big block heads don't flow as well as my ported cathedrals, and those heads will make 600+ hp on a 454.
Thread Starter
Teching In
Joined: Feb 2008
Posts: 31
Likes: 8
From: NJ
I actually found a great deal on an LS2 block so looks like it's no longer a problem. I'm going to bore and stroke it out to 408 with some proper heads, a matching cam and a Super Vic intake. Should run well (I hope)
LS1/Gen3 383 strokers typically do not gain much if any hp over a well done forged 347. The strokers will normally gain 25 to 45 foot pounds of torque over the forged 347. This seems to be due to the 3.9 bore size the LS1/LS6 block is limited to and the restrictive intake manifolds typically required.
Often the 3.9 bore will limit the intake valve size to about 2.04 any bigger and the valve gets shrouded and does not flow as well.
My Brian Tooley hand finished TEA LS6 Stage 2.5 from 2003 could flow about 345 cfm (2.08 valve) on a 4.125 bore, 335 on a 4.0 bore and 320 (2.04 valve) 3.9 bore.
Why give up 25 cfm of air flow and potentially 45 to 60 hp by using a 3.9 bore?
I'm sure TEA's newer heads are even better nearly 15 years later.
I went with a 3.9 bore LS1 383 with the TEA's mentioned above and a small cam for my street driven 91 RS Camaro but if the RS was going to be a RACE care only a 4.125 bore block or bigger would have been acceptable to me for the above reasons.
Best wishes on the build.
Often the 3.9 bore will limit the intake valve size to about 2.04 any bigger and the valve gets shrouded and does not flow as well.
My Brian Tooley hand finished TEA LS6 Stage 2.5 from 2003 could flow about 345 cfm (2.08 valve) on a 4.125 bore, 335 on a 4.0 bore and 320 (2.04 valve) 3.9 bore.
Why give up 25 cfm of air flow and potentially 45 to 60 hp by using a 3.9 bore?
I'm sure TEA's newer heads are even better nearly 15 years later.
I went with a 3.9 bore LS1 383 with the TEA's mentioned above and a small cam for my street driven 91 RS Camaro but if the RS was going to be a RACE care only a 4.125 bore block or bigger would have been acceptable to me for the above reasons.
Best wishes on the build.
Staging Lane
Joined: Dec 2004
Posts: 65
Likes: 10
From: Weatherford, TX
Everything I've seen says this is the safe number. Some go less if they are going to boost it to the moon but 4.030" seems pretty common on LS2 blocks. Probably opens up the breathing a little bit for a later model head as well.
I have another LS2 block at RED right now, and it's going out to 4.155", with Darton sleeves of course.