valve size in Stage 2 heads for street?

[990 T]

If you were building a S2 for the street, would you think it'd be better to use smaller valves in S2 aluminum heads to keep up the port velocity, than going to larger valves? My goal is a high nine-second street car which will see daily use. The planned engine is a 274 ci S2 with 9:1 cr, a 3200 stall TC, S2 aluminum heads, and converted 4-bbl intake. Turbo likely to be 70 - 76 range, and cam likely to be a Erson 222/218, or 224/218 roller. Since it is a street car, I'd prefer to keep the power a little lower in the rpm range, but S2 heads usually see higher rpms (6500 +), and hence can use a large 2.05 - 2.10" intake valve. I know that Champion headed S2 cars with 1.90 " intake valves can run well under high nines, so I question the need to go larger than the stock 2.02" intake valve on the S2 Buick heads. For the same reason, I like Terry Houston's 1 3/4 " S2 headers, as they are smaller than the 1 7/8" tubes used in ATR's S2 headers. I think the name of the game is still port velocity, whether the engine is force-fed or not. Any thoughts? TIA.

 

[John Wilde]

I am not sure on the valve size but I can tell you the following.
All the stage 2 Buick race motors I have seen at Duttweiler's
including the one I just sold had 1 3/4 tubes. This includes
dyno proven 1500 hp units. I don't think the 1 7/8 tubes are
needed.

Now regarding your cam, we need to talk. That is way to small
not just for the heads but for the cubic inches as well. I have
run a 224/224 510 lift in a street 231. I would go with like
a 230/230 to keep the street manors. There is a man on this
board with a stage 2 car "tim barnum" I think and he really likes
this cam. He drives his car a lot. Email him !!!!

The compression will help the car get on boost but probably limit
your boost to around 15 or 16 psi on 92 octane. I am sure it will
still have enough power for you though =)

Good luck and let me know what you do.

 

[990 T]

John,
That cam suggestion looks worth investigating. The other cams mentioned were suggested in pursuit of having a street driveable S2 combo that won't require a high stall, and which gives good response. I have a huge Duttweiler roller that is only a track cam, and is just way too big for what I need. Glad to hear the 1 3/4" headers get Ken's stamp of approval. When it gets closer to coming together I'll give you a shout. Thanks. John.

 

[S2V6RACER]

Originally posted by John Wilde
I am not sure on the valve size but I can tell you the following.
All the stage 2 Buick race motors I have seen at Duttweiler's
including the one I just sold had 1 3/4 tubes. This includes
dyno proven 1500 hp units. I don't think the 1 7/8 tubes are
needed.

Now regarding your cam, we need to talk. That is way to small
not just for the heads but for the cubic inches as well. I have
run a 224/224 510 lift in a street 231. I would go with like
a 230/230 to keep the street manors. There is a man on this
board with a stage 2 car "tim barnum" I think and he really likes
this cam. He drives his car a lot. Email him !!!!

The compression will help the car get on boost but probably limit
your boost to around 15 or 16 psi on 92 octane. I am sure it will
still have enough power for you though =)

Good luck and let me know what you do.

Are the Houson Stage II headers out? I didn't think they were.