I would use the small chamber head ( N/A) as to bump up the compression since you will want to run a lower static compression ratio later w/the turbo.
Some people here does not recommend useing the small chamber head,,, ,but I do & so does Larry AKA Twisted 6. We have used them in the real world of racing & just plain driving on the street ;-) I was very,very happy w/my results using the small chambered 194 cyl head.
MBHD
Hank, just to update you on this matter. Tom had the 194 small chamber head casting with the 1.94" valves in it, and the big chamber head with the 1.94" valves in it, that were both used in the dyno testing, flow tested this week. The small chamber head was down on flow by over 20 CFM compared to the big chamber head. That is probably why the HP was also down when we tested that head. So, we have tested the small chamber head in 2 ways, both with flow testing and with a dyno, and have consistently seen that it is showing us, both less flow and HP compared to the big chamber head are lower on both counts. We will test it again on the 250 dyno test coming up, but if it still shows us the same results, I can only say that if you and others have experienced gains in using that head, it is more likely from something else you might have changed or done you haven't considered, instead of the head itself.
Its like the guy who makes one pass in his car at the track, and then decides to let 1/2 a pound of air out of his slicks, and when he makes another pass an hour or so later, he goes 2 tenths faster. Not knowing that the track officials sprayed VHT on the track since his last pass. So know he thinks he honestly picked up 2 tenths off his time by dropping his air pressure a 1/2 pound. Im just saying, that there are dozens of variables that could have lead to a better ET after your head swap that might lead you to think the head was the reason of the gain you experienced. You might have gotten better as a driver for instance, the track might have improved, the air might have been better, and on and on. Im sure you know, but others that race occassionally, might not realize that track temps, tire/slick temps from round to round, barometric pressure and air density and so many other factors will affect a cars performance one pass to the next. And if they dont know that any of these factors have changed, they will mistakenly think they did something to create the increase or decrease, when they actually had nothing at all to do with it. Thats how many "urban legends" in racing have started over the years.
