ViceCityPerformance

So I am getting a fully built ls3 longblock from TSP. Its going in my GTO.

This engine is going to be force fed by my tvs2300. I plan to spin this thing as fast as it can go. The 2300 comes from Magnuson
Intended for the stock 243s.

Here is my dilemma.

I wanna run a mild roots blower cam like brian tooleys (stage 1) or TSPs in house Blower A cam.
The issue is that with my stock heads I am seriously choking this 6.2 even if they were ported and on top of that these cams were developed and intended for ls3 style heads so running the stock ported 243s & or PRCs might not allow for the absolute best performance the cam was intended to deliver.

Would it be beneficial for me to switch out my ls2 blower manifold for an ls3/9 one and run ported ls9 heads with either cam?

Or just run the PRC 243 aftermarket castings.

My goals on a proper loaded dyno are 600's (tipping in to the 700s on a dynojet).

Brian Tooley Racing

iTrader: (13)

If your goals are 700 rwhp on a Dynojet then you should use some LS3 or ported LSA heads and run at least the Stg II cam, it has the same overlap as the Stg I (-10 degrees) so it still has a nice idle.

ViceCityPerformance

Brian, so what your saying is with your cam run the ls3 style heads and get myself a port matching blower?

Brian Tooley Racing

iTrader: (13)

Yes sir.

redtan

iTrader: (5)

Ported 243s vs. OEM square port heads are pretty much a wash in terms of flow, and both will easily get you to your goal.

ViceCityPerformance

Its not just about the flow. The valve angles or correctly said "the way the heads flow" affect my cam selection. The whole aftermarket these days is based ofd of the rectangular port ls3/9 heads. A brian tooley cam wont perform the same with the 243s as with the ls3/ls9 heads

ViceCityPerformance

Brian,
As soon as I can get my blower manifold switched to the rectangular port. You will have my business

Brian Tooley Racing

iTrader: (13)

Sounds good!

To clarify, valve diameter acts like cam overlap to the engine, so if I were to cam the cathedral port heads with smaller valves, then I would probably add some overlap to the cam.

ViceCityPerformance

You lost me there... Please explain the valve sizes relationship to choosing the cam profile

Brian Tooley Racing

iTrader: (13)

Larger valves flow more air at low lift, which to the engine behaves mostly like adding cam overlap, make sense?

dogsballs

Are the ls9 heads like the lsa heads, ie have a thicker deck than the normal ls3 style rectangle heads

ViceCityPerformance

Overlap is when the intake valve lift and exhaust valve lift duration is long enough to allow for both to be open at the same time. Enough overlap causes reversion of intake and exhaust gases at light throttle causing loss of combustion efficiency.

How do larger valves have the same effect as more cam overlap? Is it because the opening and closing of the valves rapidly causes reversion?

carbuff

iTrader: (8)

I'll take a stab at the question, but I'm sure Brian can explain it better...

I think what Brian is suggesting is that the larger valve allows a larger volume of air to pass through the valve at a given lift. So if you use the same cam with two different heads, one with smaller valves and one with larger ones, the head with larger valves will allow a larger volume of air pass through the valves at given lift.

Thus, during the cam timing when overlap is occurring, the larger valves will allow more volume of air to flow from intake to exhaust, effectively acting like more overlap.

At least that's my interpretation.