chb280z Posted June 11, 2008 Author Share Posted June 11, 2008 Any ideas? Quote Link to comment Share on other sites More sharing options...
Pyro Posted June 11, 2008 Share Posted June 11, 2008 Yes, the P79 flows like a P90. Yes, you can run it with the crack if the shop had pressure tested it and it didn't leak. I have a crack on my turbo head just like that and run 14 psi of boost for the last 4 or 5 years. A friend on mine made a turbo engine with the P79. Ran ok, seems to be a little more prone to detonate than my P90 set up. He had to run a little less timing than I did. But that is just one case so I'm not sure if the head was the problem. You can make a nice turbo setup with the n42 block and N42 head. Just can't run as much boost when using the stock cam and turbo. It will run fine at 8 psi of boost. You would need to limit timing to 20 to 24 degrees with 8.3:1 cr (stock 75 to 80 cr). However, if you run a msa stage 1 or 2 turbo cam and a bigger turbo with a free flowing exhaust turbine, then you could run maybe 12 or 14 psi of boost on pump gas with 8.3:1 cr. if you use a P79 head, make sure to use the head gasket that matche the block. If you use a F54 (81 to 83) head gasket on a N42 block (75 to 80), it will over heat. Quote Link to comment Share on other sites More sharing options...
chb280z Posted June 11, 2008 Author Share Posted June 11, 2008 Thanks that is good news maybe i will go pick up my head then i didn't want to pay to pick it up if it wasn't going to work. If i could just get a few more oppinions that would be great. Also should i maybe since my boost will be limited run the N42 w/ a 1mm head gasket which will take my CR to 8.5:1 so i can get a little better low end power? and then let the 8PIS take over from there. will i still be able to use 87 octane gas? Quote Link to comment Share on other sites More sharing options...
Pyro Posted June 11, 2008 Share Posted June 11, 2008 8.3 or 8.5, doesn't really matter than much. But yes, the off boost power will be better with 8.4 as compared to 7.4:1 cr. Don't think it would be possible to run 87 octane with 8.3:1 cr and a turbo You will need to lock out the stock distributor (silicon up the advance slots) and set timing to 20 degrees. Continue using the vacuum advance and make sure it works, if not mpg will really suck. And use a Bell Engineering FMU to increase the fuel pressure to 55 or 60 psi during 7 psi of boost. Should make a mid 14 second car at 96 mph and a low 14's at 100 with an IC. Can try more timing for more power, but 25 degree will be about the max. I also recommend tightening up the afm flap 7 or 8 teeth. Quote Link to comment Share on other sites More sharing options...
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