408 CI Made Some Changes! Rwhp?
12-09-2006, 08:33 AM
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408 CI Made Some Changes! Rwhp? My original set up put down 515 rwhp. We made a couple of changes do to cracked heads. What kind of rwhp are you guys getting w/ similar builds? 408 stroker, comp cam 244 248 .610 .618 112lsa, dart 225 heads polished, and slightly ported, 12:3 cr, fast 90mm intake, kooks 1 7/8 long tubes no cats. Three things changed. The cr was 12:8, this was dropped to 12:3 because we wil not be shaving the heads. I bought the car w/ motor already built and the guy told me the cr was 11:1 (not true) along w/ a few other things we found. Motor was to have been built for nitrous, but rings were gapped at .017, and are now gapped at .027. The heads were AFR 225. They were ported to the max. There was no material left in them. The machinist, and engine builder said they had acctually been over ported, which lead to them eventual cracking. I was wondering if the potintial of the motor was comprimised because of the ports in the heads being hogged out to the point of losing velosity. Motor will be back together today. Me and the guy that built it will be going to get our cars tuned and dynoed mid next week. It sure would be great to have at least the same rwhp I had before. We were amazed I had been driving on 93 octane w/ 12:8 cr. There was only an occasional pinging. The tuner did a good job w/ this, there was no damage to the pistons. I will be adding an octane boost to the gas. I'm interested in what you all have to say. Thanks!
Rob Edwards
Rob Edwards
Last edited by 97Rob; 12-09-2006 at 08:43 AM.
12-09-2006, 09:35 AM
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i think you will lose hp.i think you will be in the 490-500 hp range. you dropped your c/r half a point and the afr heads flow big air. it is possible they may have been over-ported bur 515 rw is a good number and the darts flow quite a bit less so maybe i'm wrong but that is just my opinion.anyway you look at it your motor is now set up better for the spray so get us some good jug numbers to gawk at.
12-09-2006, 10:04 AM
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It will be interesting to see what we come up w/ next week on the dyno. I will post the results. We were hoping the increase in velosity at the heads would make up some difference. I would think this set up should still make over 500 at the wheels.
