[Unknown User]

How much boost do you guys think a motor with a compression ratio of 10.1:1 would handle.This would be on 93 gas and ignition timing retarded all the way.Also this motor has 4 valves per head, as design that is suppose to be fairly denation free.

 

[szlash280z78]

4 valves per head? How many heads do you have? Or do you have 4 valves per cylinder? From what I have read, thats too much compression for a boosted engine.

 

[SleeperZ]

Check out Corky Bell's book Maximum Boost. He has some guidelines based on boost and fuel octane. Without looking, you'd be hard pressed to get any power out of the motor with the ignition retarded, so to get any power, you'd probably be limited to 6-7 psi WITH a good intercooler. 8:1 with 20 psi is much more achieveable on that fuel, and you would make gobs more power.

 

[Brad-Man]

What SleeperZ said....

What engine are you talking about?

Inquiring minds want to know.....

I personally would use 8.5 to 9.0 c/r and limit boost to 15 lbs for street. For race drop to 7.0 and 20-25 lbs.


Brad

 

[Tony D]

Hondas Do It.

They are running 20-30PSI with 10:1 C.R. But that is on a Combustion chamber designed after years of R&D in F1!
I don't think the number of valves has ANYTHING to do with the ammount of boost you can run, it's in the Detonation-Resistance inherent in the design of the combustion chamber...

 

[bama16]

Re: Hondas Do It.

i have a quick question about detonation? what causes it to happen and when? i have an '81 280zxt and am happy with the stock 6 psi. how high could i safely go w/o intercooler and then with? i don't think i can imagine the car with 10+ psi.

 

[Tony D]

Stocker...

Rund out of fuel map at 10psi boost. You make NO more power over 10psi on an otherwise unmodified car...
Try it, you'll like it!
Detonation is when the fuel mixture ignites of it's own accord outside of the spark-ignited flame front in the combustion chamber.
It causes t\errible pressure spikes and temperatures insidethe chamber. It breaks things!
It can be caused by intake air being too hot, and lighting off the fuel mixture.
It can be from glowing carbon deposits startingthe process.
It can be from using cheap gas with a bad octane rating, meaning it is easily ignited by heat of compression...

Basically, you end up making a gas engine work like a diesel, without timing of the fuel entering the combustion chamber. Kinda like using ether to start a diesel: even a diesel can go BOOM!

 

[Unknown User]

the motor is a VE30DE(maxima)

I meant 4 valves per cylinder. The spark plugs are hemi style. I have alway heard that the pent roof designed head will resist detonation better than others. As to why I think I can't get aftermarket ignition is the VE motor has a distributorless ignition.I can't get aftermarket headgasket for this motor either, but could I stack two stock headgaskets??If anyone know of a fairly cheap ignition that might work for this car let me know.

Thanks
Jason

PS I only asking you guys about this, because the people at the maxima forums are young and inexperianced.

 

[Unknown User]

What about a Air/water intercooler

A while back I bought a Air to Water intercooler. The "core" measures 10x3.5x3.5 and has 2in inlet/outlet. Do you guys thinks I might get 10psi with that and Race gas.What about the cooling effects of nitrous.

thanks for the input
Jason

 

[Tony D]

Open Deck Aluminum Block?

Isn't that the open deck aluminum block? If so, don't get too greedy! The hondas put a girdle into the top of the open deck to keep the cylinders from walking around under boost. They actually have problems with the cylinders EXPLODING if not sleeved.
I would keep with a low-boost (maybe 5-7psi) and install the intercooler. If it tolerates that for a while, and you get the fuel maps worked out, you might try 10.
Stillen has a supercharger for this motor, I believe, so I'd get with them and check their experience. They have some good R&D information, if they're willing to part with it...