jtmustang

really almost half a point that is more than what i would of thought,so probably not a good idea to do that in my case especially with a supercharger

r.barn

Its one of those things good engine builders will say to stay away from
and at the same time hear of lots of people that do it with no problems

I've also seen some post's where guys were having horrible detonation problems

You start to get into some really techincal parts of the combustion process
with flame travel and quench area and all kinds of shyt coming into play
that will effect whether it works fine or is a total nitemare.

I bought new 64cc heads to lower my compression[&:]

jtmustang

so what about a procharger kit.i have heard good things about it. i want the intercooler anyways.what is there entry level kit like i already said im only lookin for 8lbs of boost .where?how much?

jtmustang

whats up nobody has any other info for me ?? procharger with 9.7 intercooled i know what kit ??? methanol???

knewt

Well my 7.5 to 1 set up ran for 300 miles and my #4 piston came to peices. I was running a keithblack hyperutectic with 13cc dish.I wanna say that the stock pistons took WAY more abuse than these P.O.S.'s
Most likely my tune was off but I'd say stay away from hyper pistons with boost.I never had problems with my stockpistons.time to find a used block. On to engine #5.Ihate302's......
7.5:1 compresion and 5lbs boostwith a 6000rpm msd limiter. WTFhappened here?!

only90s

My advice would be to run aVortech 6lb kit with a Power Pipe and Methanol Injection-that should give you about 8lbs of boost....2k for kit, plus another $450 for the Anderson Ford Power Pipe and Mr. Freeze Methanol kit.....dont think you can touch a intercooled Pro Charger for that price-but not sure.

http://store.summitracing.com/partde...p;autoview=sku

http://www.andersonfordmotorsport.com/


GET IT TUNED...no matter which way you go with all that compression.....good safe tune with the Meth or intercooler and you should be fine.

67mustang302

There are a whole crapload of variables that go into what CR you can run with what boost, like r.barn said. Head material, cooling system effectiveness, piston material(hypers are generally NOT recommonded for f/i or nitrous use), quench height, combustion chamber shape, combustion chamber size, quench AREA(different than height, gets into chamber shapes), spark plug placement, intercooling, fuel availability, engine management, TYPE OF F/I USEDand on and on. VW developed a prototype Golf GTI car that used direct gasoline injection, and was turbo charged. It ran like 12psi of boost with 10.5:1 CR on 91 octane fuel with no problems, produced wild amounts of power from a little 4 banger, but never went into production.

You can run more boost pressure with a centrifugal supercharger than you can with a roots, because the centri runs cooler than a roots, and doesn't start to make boost until combustion pressures are starting to drop off, whereas a roots is boosting through peak combustion pressure increasing the liklihood of detonation. That's why a lot of companies that make centris say you can safely run up to 9.5:1 on pump gas, but the roots blowers only recommend a max of 8.5:1(in most cases).

A very well set up engine will be able to run more boost with a higher CRwithout detonating than a crappily set up engine with less boost and lower CR. Cam selection also plays a huge role as well,camshaft durations and especially the intake valve closing point have a tremendous impact on dynamic compression ratios and thus, how much boost you can safely run

vtecwho

^^ he said everything very well, stroke, head shape (the list goes on); all have a role in combustion. when the piston sucks air into the cylinder it is going to be A TON cooler than the air when its compressed!! HOLLY shiz, THEN you get in to the different variations of PV=NRT (the ideal gas law). if you were a VERY well rounded person in science and engines you maybe able to figure out YOUR ratio..... good luck.

thats why you need a plan before you build.... i just figured that out.... glad i have the gt irons

grabbem88

what about cylinder pressure fella's

aode08

id just install a set of copper head gaskets. Lower 1/2 point and have an unbustable gasket.