40-50 psi?
 

I've been watching a few videos of engines (aussy build ;) ) running 50 psi. all drag engines but RB30's and even a sr20 running more than 40psi.

Does that much boost seem doable on our blocks? Say for sids sake as he drags his car more an any of us here.

We get good power from 20psi with a 3L 16v engine. But what about our motor (any config 8/16v 2.5+L) with low compression boosting 40 psi of boost?


This guy use to be across the road from my shop.

Its fair to say the engines are of the same vintage too!

If you can sort the head coming off the block, hi boost levels on the right gas should be in reach you would think.

aren't those iron/steel cast blocks?

RB is cast iorn.
SR are aluminium.
Even F20 engines are aluminium and people go crazy putting boost in them.

Well the SR is slightly newer, '89. RB is '85.

Weld the head on old-school. It would help if we had more cylinders for more headstuds. Billet block?

Billet block would be nice. 355-T61 aluminium :)

deck plate

I believe that there is more interest from people (hence more developement) on 80s civics toyotas and nissans thats why they have found solutions to run so much boost on their cars. Our cars are more expensive to work on and I guess since they have a transaxle which is a weak link for drag racing many people simply dont bother. On the other hand the transaxle balance benefits are the main reason our cars make excellent track day toys. I guess with the right block development our cars can run higher boost levels safely. Dont forget we have 2,5 engines compared to the 1,6 civics. Just my 2 euros...

I think we might see a couple people pushing some pushing high pressure in the future. I might crank it up later in the year. Problem is that our blocks just flex too much and the head bolts are spaced too far apart.

My plan is to o ring the head and use a copper gasket. I think the rest could handle it.

I'll need my fuel system sorted first. It seems to make a lot of power per psi.

Who knows though, maybe someday I'll be content.

Haven't got the gasket yet but here's the block and rings as of late last week. Gasket will be made of copper.
I was very hopeful that the deckplate and massive 9/16" headstuds clamped down much higher than stock would save me from doing something like this but no.
Not even at lowish 1.3bar boost. We were popping Cometic h/gaskets every race meeting. Not due to detonation either. So here we are now. Next......

how about a Mosler MT900 running boost....




how Mosler was born....

Michael Mount discussed some testing he did a while back about larger head studs and stated his test data showed that too much clamping force can actually make things worse (too much clamping force warping the surface). I wonder if this may be some of your issue. I look forward to seeing how things go with your new mods. I always appreciate your willingness to share information. :)

Also, I would like to see someone build a 7:1 CR motor at higher boost and see if it improves the situation. Theoretically you can make more power with lower peak cylinder pressures.

http://www.modularfords.com/threads/...boost-pressure

The jury seems to be out on the whole how much tq to apply to headstuds Shawn. I've heard arguments made from both sides of the camp and can't really show proof of irrefutable evidence that one is absolutely correct. Really, we probably should have been a bit more diligent in measuring bolt stretch I guess. Also, how much do the alu blocks change in hardness over 30 years of heating and cooling? Does the block yield and not the stud? There is another school of thought that perhaps having the stock intake manifold which produces a lot of early/mid range tq might increase the chance of the block flexing as opposed to your shorter runner style that might make it a little more progressive or linear and also occur a bit higher up in the rpms. Not sure on that.

I think the lower c/r model would be looked upon as a step backwards, but perhaps with the right combination of tuning, timing and turbo it could be made to work. Be an interesting experiment. It might be also dependent on where you ran the car. Streeter vs drag vs track (What style of track?) would require a certain response from the motor.

I think the costs of engines and availability of parts must play a part in why more 951 owners don't push these numbers. Big power internals and turbos cost extra $$ cause of the specialty of the car.

There is a $500 parts car with the engine in it over in the classifieds. Cheap extra engine for someone who might wanna try.

More on subject, my friend used epoxy to seal his head on a Honda H23. He eventually blew the motor but did get 30lbs fairly steadily.