Cam recomendations
Since the heads have had a valve job already.
Could i just have a bigger intake valve installed and leave the exhaust valve stock since its the same size as ls1 head?
Anyone ever do this with the 706 heads with the small intake valve and how much would it cost?
Could i just have a bigger intake valve installed and leave the exhaust valve stock since its the same size as ls1 head?
Anyone ever do this with the 706 heads with the small intake valve and how much would it cost?
TECH Apprentice
Joined: Apr 2019
Posts: 365
Likes: 133
From: California
If you have the funds get your heads ported; however if you don't have the funds run your heads in stock form since do they flow well. If you swap to a 2 inch valve without the mods to support the bigger valve you could lose cfm and power.
TECH Apprentice
Joined: Apr 2019
Posts: 365
Likes: 133
From: California
Do like @SLP IROC-Z says and sell you 706 heads to buy a set of 243 heads. The 243s are the best flowing cathedral port heads produced by GM plus with your 5.7 liter LS1 you will get a bump in compression to go with the improved flow.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?
Pouria Savadkouei
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
TECH Senior Member
Joined: Jun 2016
Posts: 22,308
Likes: 3,625
From: Central Cal.
10.1:1 241/853*
10.5:1 243/799*
10.9:1 706/862*
*stock .051 gasket 3.905 dia
as we know with the lq9 10.1:1 vs lq4 9.4:1 otherwise identical gm claimed 15hp from 7 tenths in compression thats about 2hp per tenth. So theoretically if both the 706/862 flowed as well as a 243/799 youre looking at around 10hp difference from the compression.
My opinion is ptv is going to be very tight with stock heads and the cams youre looking at. You really need 11.5 compression with those cams but won't be able to run a thinner headgasket or mill the heads to get there. At 10.5 stock 243s or 10.9 stock 706s, the car will be faster down the track with 243s. But if you dump all the money into the 706s and see if they can recess the valves without killing flow so you can mill them to 59.5cc and run an .040 or .045 headgasket for 11.5 the 706 will be faster. Question to ask any ls porter is which head can flow the best ported and which head will be able to get 59.5cc chamber volume without reducing ptv.
10.5:1 243/799*
10.9:1 706/862*
*stock .051 gasket 3.905 dia
as we know with the lq9 10.1:1 vs lq4 9.4:1 otherwise identical gm claimed 15hp from 7 tenths in compression thats about 2hp per tenth. So theoretically if both the 706/862 flowed as well as a 243/799 youre looking at around 10hp difference from the compression.
My opinion is ptv is going to be very tight with stock heads and the cams youre looking at. You really need 11.5 compression with those cams but won't be able to run a thinner headgasket or mill the heads to get there. At 10.5 stock 243s or 10.9 stock 706s, the car will be faster down the track with 243s. But if you dump all the money into the 706s and see if they can recess the valves without killing flow so you can mill them to 59.5cc and run an .040 or .045 headgasket for 11.5 the 706 will be faster. Question to ask any ls porter is which head can flow the best ported and which head will be able to get 59.5cc chamber volume without reducing ptv.
LS1Tech Sponsor
Joined: Jan 2008
Posts: 2,241
Likes: 1,536
From: Ohio, Georgia, Nevada, Texas
We do offer our Single Plane cams. Those have tighter LSA's if that's something you're after. Keep in mind these were designed around applications with short runner intakes and open exhaust systems. They aren't the easiest to tune.
Feel free to use our cam timing calculator to compare IVO events of different cams. The IVO event Is basically idle quality. The earlier you open the intake, the more air you're taking in on the downstroke (at the expense of idle vacuum).
This gives some food for thought. Let us know if we could be of any more assistance. We'll be happy to help!
LS1Tech Sponsor
Joined: Jan 2008
Posts: 2,241
Likes: 1,536
From: Ohio, Georgia, Nevada, Texas
We like trunnion kits anytime rockers have over 50k miles on them. BTR does a really nice job with their kit and we have bearing and bushing style kits as well. We have the installation tools to make the job easy as well. Just PM us and we can put together any part numbers you need to complete the job.
update
picked up a tsp tsunami v2 so that's the cam im going to run. I've decided to get prc stage 2.5 ls6 heads but wasn't sure if I could get 58cc combustion chamber and still have enough ptv clearance?.
I would like to achieve the most compression possible.
picked up a tsp tsunami v2 so that's the cam im going to run. I've decided to get prc stage 2.5 ls6 heads but wasn't sure if I could get 58cc combustion chamber and still have enough ptv clearance?.
I would like to achieve the most compression possible.