Compression Upgrade

[cubanboi89]

So I was reading on the internet just for other basic information and ran across something about compression upgrades about how it increases gas mileage and power, but I couldn't figure out how its done for the SHO and I'm interested! Can I get guidance on how to do this?

 

[YZF-Ford]

Different pistons, shaved heads, or thinner head gaskets (if they are even available.)

 

[rubydist]

except that shaved heads are a very bad idea on an ohc engine, unless you have adjustable cam sprockets - else you end up changing the cam timing which is a much larger negative than what you gain by the shaved heads.

and, custom pistons are quite expensive for these engines since they are relatively rare in terms of speed equipment, so you would have to drive it for another 20 years to save enough gas to make up for the investment in pistons, etc.

 

[jimtash]

You don't want to go overboard on the CR especially with modern gas. You'll have better results for a street car if you raise it slightly and also bore out the cylinders. Street cars need torque and that comes from the size of the piston.

Modern engines have somewhat overcome it with direct injection but there's a downside as well. While many of those engines are running some really high compression ratios, it's causing the intake valves to carbon up quickly. And that's because oil from the PCV and fumes from the EGR aren't being dissolved and washed away like they normally would when fuel is atomized with the incoming air.

 

[shobote]

Different pistons, shaved heads, or thinner head gaskets (if they are even available.)

Shaving heads or thinner gaskets is old school for pushrods, not OHC's. The cost for HC pistons is not worth it to most, even if you could do the labor. You also need higher octane with higher comp. and the costlier gas is going to more than offset mpg improvement.

 

[luigisho]

You won't get any financial returns modifying most any car. Do it because you enjoy it or leave it alone. The best fuel economy modification you can do to your specific sho, is fix what's wrong with it. If you can't afford to maintain a car, don't go trying to modify it. Been there done that.

 

[YZF-Ford]

Didn't think about the cam timing thing.

 

[SHOspazz92]

Josh sells high compression pistons @ shonutperformance.com

Then you have to get it built, get it tuned and run on 91-93. Good luck!

-Sam

 

[cubanboi89]

Man thanks you guys sounds like alot of money to spend for not much tuning for the engine, so I though about this as well, upgrading the fuel injectors, pump and regulator. Has anyone done exactly that and what was the out come? Still learning about the show as much as I can and all information will help.

 

[frosho]

There are no easy/cheap upgrades for this car aside from a y-pipe if you have a manual. You need to spend a whole lot of money to see big gains. As far as the fuel system goes, the stock components are more than fine for a stock or lightly modded SHO.

 

[luigisho]

Alot of us have spent alot of money trying to go faster and other modifications. More power is expensive and most bolt ons aren't really worth it with these motors. Bore/compression and pr Forced induction/N2O for good power increase. You will really like the car if you improve suspension and brakes.
Tuning only gets you so far and with the tuner cost and dyno time may not be worth a little gain. Bolt ons and tuning can wake up a larger v8 or a car with factory forced induction, but not so much with these motors.

 

[cubanboi89]

Thanks guys for the help. I thought the suspension that was on here was good but I guess it gets greater! So how much power can the stock fuel system handle and are the SHO sites the only places to get tuning upgrades? I know with the SHO source they sometimes won't have what your looking for if they are out of stock on an item.

 

[SHOspazz92]

Search button is your friend!

But as a freebie, we'll say that 300 wheel horsepower or so is the absolute maximum the stock SHO fuel system can take.

 

[cubanboi89]

Ok cool better to know that for sure instead adding power and blowing something up! Cool! Exactly what can I do to get it 300hp or close to that?

 

[SHOspazz92]

http://www.shoforum.com/search.php

 

[Ishodu]

Search button is your friend!

But as a freebie, we'll say that 300 wheel horsepower or so is the absolute maximum the stock SHO fuel system can take.

I would say its around 300 crank HP the stock fuel system would run out of steam. That is at the normal 39 PSI.

 

[Ishodu]

FYI the high compression I have off set the loss of low end TQ High lift Cams cause. If I drove the car everyday it would be a major pain in the ass. Needing 93-94 octane all the time creates a few issues. I also find my self giving the car gas when going down hills I should be coasting in gear.

 

[cubanboi89]

When I'm going down hill if the car doesn't slow down a tad bit it maintains speed. Depending on the grade of the hill. Lol in Tennessee the grade of the hills are so steep that my car was actually picking up speed in a lower gear. One hill where my cousin lives I dropped the car to 2nd and it got all the way up to 40 mph and south Tennessee on I-24 where they have the runaway truck ramps I dropped to 3rd and it was still trying to push past 60mph.

 

[luigisho]

It would cost less for you to save your money and buy a car that is already 300hp. Either a boosted/modified SHO or something else. It costs a decent amount of money if you don't have access to good used parts and are really good with wrenching it yourself.

 

[cubanboi89]

Yea I would check out the junk yards for another SHO but the junkyards here charge an entry fee... Wack!