I am in the process of building my SBC for my 22' Pachanga. I am looking at a set of vortec heads with the 2.02/1.60 valves and haven't chosen a cam yet. I will use the Edelbrock Vortec intake good to 5500 rpm and a 650 cfm carter carb. It looks like I can hit the 400 HP level without too much trouble but will be limited by the exhaust. Where is my upper limit until I can afford to upgrade?Any hydraulic flat cam recs?
Thanks,
Ken

PS: I've got all the SBC books and have been reading my but off!!Here is a great article for all you SBC fans (read all the parts!!):
http://www.73-87.com/chp/gm350.htm

Dear Kimken
My camshaft recomendation would be a Comp Cams Extreme Energy automotive camshaft wth 218/224 intake and exhaust duration @ .050 lift with a 110 degree lobe sep angle. Comp Cams may suggest a 112 degree lobe sep angle. Either one will be fine without much of a performance difference.

All of the STOCK small block engines that I've modified with aftermarket exhaust manifolds have shown very small performance increases.

The big block Mercruiser is different and will usually show a good performance increase with aftermarket marine manifolds.

I would have to guess that at the 400 horsepower/5,500 rpm range that you will need some good aftermarket manifolds for the small block or you will be throwing away about 10 - 12 horsepower.

I should mention that an automatic 15 to 20 horsepower increase is always found between tube style headers and stock exhaust manifolds with a stock small block in an automobile. There is a big difference between automotive headers and stock automotive exhaust manifolds. There isn't nearly as much difference between the stock marine exhaust manifolds and aftermarket marine manifolds, particularly on a small block Mercruiser.

Dennis Moore:

When raising the performce of SBC's what are the limits of the Merc manifolds/raisers and exhaust systems? From the other direction when, and what improvements should be considered?

Doug Hess

I think a lot of issues arise when you get reversion. Currently, I'm running a 250/252 @ 50 with .584, .594 lift on a 112 center. With the standard riser stainless marine manifold, I am right on the edge with reversion.

I think that's what you really need to look out for !

Well On a stock 5.7l/260hp I gained 2.5mph going from thru-hub stock exhaust manifolds/risers to Stainless Marine 4" straight thru-hull...2.5 mph figures out to be probally 30-40hp....I would say on a modified motor you probally could add some more depending on your cam and intake/carb......

BH