Timing usually tweaks 10hp on Mustang at least. I'm sure the U.S. spec computer has the timing retard and that probably lose a couple ponies. However with the raised boost 310 will be no problem. All it means is that if the computer is smart well be around 10hp behind the jdm spec b/c of gas with the same mods. Meaning same exhause/cats and etc.

I'm not 100% sure but isn't the octane ratting different in asia. What i mean thier 99octane is actually 95 here or something. I thought we go by a different rating units.

 

Cali 91 CBG is around 96.5 RON

Erik

 

Posted by: silverkorn
I think with the proper A/F ratio you should be able to run 92 octane with 310hp. I don't think you need to use race fuels until you start pushing about 40%-50% and up above stock hp.

 

You are wrong. With a high compression engine like the EVO's you will get detonation with lower octain gas once you try to increase boost. It will not be super easy to just increase boost and regain the horse power mitsu took away.

 

The compression ratios is probably 8.8:1 which is ok for a turbo cars. Many after market turbo cars run stock compression of 9:1 or more. Cadillacs have a compression ratio of 10:1 N/A and it is design to run on regular gas.

Like i said before if they retard the timing we will lose horse power but maintain a safe combustion.

That means with the sunoco 94 would be around 100 RON like japan?

 

The Evo's compression ratio is 8.5:1, not high at all for a turbo car.
Also remember that the USDM version will be tuned to run on 92 octane to begin with.

Not saying that tuning a fuel curve is easy, because speaking from experience it is anything BUT easy.

I know that you won't get 310hp just by raising the boost, there's a lot more to it than that.

However I do believe that 310hp is very attainable on 92 octane, with the proper A/F ratio and timing, detonation shouldn't be a problem.

 

ummm i dont think your gonna need race gas, just by upping the HP by 20-40

 

First, 8.5:1 compression is high for a turbo charged car. When you run a engine on forced induction it acts like increasing the compression. So 8.5:1 (turbo) is like 10.5:1 (N/A).

Second, the car will be tuned to run on 92 only in california (and other western states with bad gas). Mitsu will most likely sell two versions. The cali version will have lower horse power (from retarted timing) so that it can run on the 92 octain water they sell there. The rest of the country will have a car tuned for 93 octain. The 93 octain version is the H.P. figure they will advertise.

 

Cadillacs don't have turbochargers last time I checked.

Next you are going to tell me "Pontaic GTO's had 10.25:1 compression. And they were made in the 60's"

 

i thought gto's are supercharged...or na...but def not turbo

 

8.5 is NOT high for a turbocharged car I've been racing cars with forced induction for 15 years. 8.0-8.5 is usually what cars run with high boost. On the other hand, cars with nitrous need higher compression. They will have to have Cal. emissions...but most cars in the US are rated at 91-92 octane no matter where you live (that is if that particular car requires premium fuel). The car companies know that 91 octane is readily available everywhere...but anything higher can be harder to find in certain places.

 

Originally posted by: MKO
You can't simply say that 8.5:1 T/C = 10.5:1 N/A. It depends on how much boost (psi) your running through the motor that will give you the final compression ratio.

Also the RSX has 11:1 comp. ratio stock, so does the C5 Vette. Both have forced induction aftermarket kits that can be bolted on and run on 92 octane. Granted they are low boost kits, but both increase hp levels at least 50hp over stock to the wheels.

Mitsu is known for tuning their ecu's on the rich side, to take into account all the variables that could go wrong with marketing a T/C car to the general public. Ie. customers using cheap gas, not getting recommended tune ups when scheduled. etc....

This leaves a little window of opportunity to take advantage of with that rich fuel curve. I'm not saying that just by raising the boost you will get 310hp on 92 octane, but that it is possible with the PROPER A/F RATIO and TIMING.

Evo's in JDM have made an additional 60hp to the wheels just by changing the intercooler piping, exhaust manifold, and exhaust from the catback, with no changes being made to the ecu or boost level.

I know the JDM ecu is tuned to run on higher octane than USDM version, but you can clearly see that the potential is there being that the engines (4G63) are the same.

 

I don't know where you got the idea that 8.5:1 is a high compression engine for turbo charged vehicles. Maybe back in the early to mid 80s that was the way people thought. But now that we have precise control of timing and fuel ratios with ECU's anything below 9 is considered turbo friendly. The 1990 - 1994 turbo Eclipses had 7.5:1 and now that is considered so old school. No one will ever build a turbo engine with that low of a compression.

In 1995, Mitsubishi raised the 4G63 to 8.5:1, which is still current with today's ratio. Most DSM owners now build their engines with nothing less than 9:1 for turbo duty.

As for the race gas issue. Give me a break. These engines are so detuned from the factory that it's sick. Power is so easy to make in the EVO. 92 Octane is more than enough to make 310HP to the wheels, not the flywheel. I guarantee that anyone who puts the Japanese spec EVO on an AWD dyno, will not register 270 HP. You will most likely see a figure like 215HP to the wheels. So you see, that if you want to make 310HP at the flywheel, its more like 250HP to the wheels. Raising the boost 4 psi should get you the 50 extra horsepower you desire. Race gas not needed. The fuel system can handle a few extra psi without jepordizing A/F ratios.

If you want 310 to the wheel, then race gas might be needed to keep the Exhaust gas tempetures down below 900C. 310 HP at the tires means that the engine is generating 375HP at the flywheel. Boost levels will need to be raised to around 22psi. Upgraded injectors and fuel pump will add some security in stabilizing the air fuel mixture.

But if you want a measly 275 HP to the flywheel, just go to Home Depot and buy yourself a ball and spring valve restrictor for around $10 so that you can adjust the boost signal going to the wastegate. Add 2 psi and there is you 30HP you were looking for.

Jeff

 

i agree with 3k. you can raise the boost all you want and still only make small amount of power. but with proper tuning you can really generate power to the wheels. the only problem is that to properly tune the car you would need an AWD dyno. now you can find these a lot easier on the west coast but you got a slight chance of finding one on the east coast.

also JeffGST, the JDM EVO's are "rated" at 276 hp cause of a law in japan that no car is allowed to have more then 276 hp. last i heard, when dyno'd the car has 305hp, at the fly.

 

That could be pretty valid since the SCC Euro Evo VII dynoed at around 246whp which is about 307bhp assuming a 20% loss.

Mark