Only way to fix the terrible ssr is a bigger valve. (Less seat % ) or a 50 as the main seat.
So ya valve up grade and more csa mandatory.

 

Getting your heads ported should make a noticeable difference, go for it.

 

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?

 

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.

 

What kind of gains would i get with just getting the heads cnc ported and running the stock size valves.

 

Sell both and buy stock 243s best flowing and still more compression than 853/241s.

 

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.

 

stock 243 would flow more than if i were to get the 706 cnc ported?
I would think the cnc ported 706 with 61 cc chamber would make more power.

 

Keeping the stock valves with ported 706's would choke it compared to 243's.

 

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.

 

Thanks for the good info slp
Planning on using either katech or tsp
for the head work

 

How fast is the car now?

 

Summit how's the idle on the stage 4 cam?
Can you get a lower lsa say 110 for more idle chop?

 

It has a choppy idle with its 9* IVO. We don't have any custom options with our Pro LS cams. We could have a custom cam done for you from Cam Motion, Comp, etc. if you would like. The stage 4 is a good fit for what you're looking for and it wouldn't be a complete bear to tune. For an example of the stage 4's idle check out the video below of it in a 5.3.


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!

 

Summit thanks for the info, you have been very helpful.
One more question I was planning on getting btr trunion kit. Do you think there necessary?

 

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.