Okay so my current engine is a zetec st170 running off bike carbs, think from zx6r or gsxr and the ignition is from a megajolt. In my forever search for more power I stumbled across info about adding a supercharger. (it already has a 50hp shot of nitrous). So I have fitted an eaton m45 (think it is ?) from a mercedes. At the moment it is still on the same jets as the carbs were set at prior to supercharging.
The fuel is now fed from an MSD 2225 fuel pump to a mallory 4309 fuel regulator (which gives fuel pressure 1psi above boost). The regulator has a line from the homemade plenum and the carb float bowls are pressurised using an 8mm pitot tube. I have lowered the floats by 1mm and set the baseline fuel pressure to 2.5psi.
I had my first run out today and was surprised to find that the fuel pressure goes off the scale of my 15psi gauge on acceleration. I was expecting a boost pressure of around 7psi Is this correct? My return line is 8mm and not restricting things.
Actually after checking I think I have miscalculated my actual boost. The crank pulley is approx 130mm and the supercharger pulley 70mm giving ratio of 1 - 1.8 so 10-11000 revs of the supercharger at 0.7l per rev. Think that means I will get 12psi boost but I am confused about engine displacement. Now I'm thinkin I might need an intercooler as the boost is higher than i thought?? and if I do have to fit an intercooler which one is best there are thousands on ebay!!
I have a rolling road booked in for next week so just wanted your opinion on my set up. Is there anything I have missed? ?intercooler? The engine seems to over rev at gear change a bit but otherwise runs okay? I have fitted a bypass valve from magnatec to ease the pressure at idle. Any other suggestions will be most welcome?
Best wishes
alex
[Edited on 11/4/11 by ianjenn]
[Edited on 11/4/11 by ianjenn]
