Drax240z Posted November 3, 2000 Share Posted November 3, 2000 I came across a formula in maximum boost that will estimate the amount of power you will produce from a given engine. Of course it is not exact... I will give the formula for high value and low value, so you can get a range at least. Low HP value = 0.052 x CID x (boost psi + 14.7) High HP value = 0.077 x CID x (boost psi + 14.7) The 0.052 and 0.077 constants represent bhp/(CID*psi) and have been arrived at from dyno pulls. (the highest and lowest values achieved are these numbers) So an L28 at 10 psi boost would produce: 217.5hp - 322hp. I know its not very accurate since there are so many other factors, but it can give you something to work with. ------------------ "Gimme Fuel, Gimme Fire, Gimme that which I desire" -Metallica Drax240z 1972 240z - L28TURBO transplant on the way! http://members.xoom.com/r_lewis/datsun.html Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted November 3, 2000 Share Posted November 3, 2000 So glad you brought this up. I think it is an excellent guideline as long as we, street-driven cars, set our sights towards the low number. Anything above that introduces so many variables and it is mind-boggling to think that an engine with the same displacement could produce the hp number on the high side. When I ran my L28T, I ran 17# boost on the stock wheezer, err Turbo. According to my hp formula based on ET, MPH and weight, I had 288hp. According to Corky's formula the low hp number is 280hp. The last time I ran the GNZ, my formula said 388hp and the Corky's low number is 417hp. Again, the numbers are dead on because I had spoolup problems with the GNZ and no traction with the L28T and both affected the ET making the hp number lower. If I can match Corky's low number with the GNZ, that should get me 10.90s There are so many variables. Turbo size, I/C efficiency, headwork, octane, etc, and if you can get the right combination, thats when the fun begins. I highly recommend the book, "Maximum Boost" by Corky Bell. It is a must for anyone running or thinking turbo and great information to better understand and clear some myths for the non-believers Scottie ------------------ Scottie 71 240GN-Z http://www.mindspring.com/~vscott911/gnz.html Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted November 4, 2000 Share Posted November 4, 2000 Thanks guys:-) I have some printing and a return phone call to make. I'm sure I"m not the only one who finds it sooooo RIDICULOUS how hard it can be to get others to buy a simple book before/when they plan on spending $$$$'s. Guess that's what makes a lot of us different, word of mouth isn't always the truth till you get it from a good one eh;^) Quote Link to comment Share on other sites More sharing options...
Drax240z Posted November 4, 2000 Author Share Posted November 4, 2000 Hehe, no doubt Ross! I keep pushing Maximum Boost to everyone, but I don't think anyway that I've mentioned it to has actually bought it. Instead they ask me to look up things, or ask me to photocopy things out of it. Heh. ------------------ "Gimme Fuel, Gimme Fire, Gimme that which I desire" -Metallica Drax240z 1972 240z - L28TURBO transplant on the way! http://members.xoom.com/r_lewis/datsun.html Quote Link to comment Share on other sites More sharing options...
John Scott Posted November 4, 2000 Share Posted November 4, 2000 Cool, so a 4.3 could have between 408 and 605 hp. Thats a pretty big spread! I agree with the low end for street figuring. Especially with my engine. Boost + well prepared high flowing heads/ cam profile/ exhaust= big increase. Tells you how important matching your components can be. I need to do some reading! JS Quote Link to comment Share on other sites More sharing options...
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