Increased Compression

[Kawadougie]

Since I run nothing but Trick Racing fuel, I've decided to increase my compression to take advantage of it. Exactly what effect does increased compression do to both horsepower and torque? Are there any negative effects? The bike is a 2002 KDX-200.

 

[jaguar]

It increases power throughout the powerband but of course at the cost of bearing (wrist pin, crank) life.

 

[canyncarvr]

Fuel is chosen to fit the engine it's running in. You don't modify the engine to fit the fuel you're running (well, notwithstanding the instance of making an older engine that wants higher octane run on what's currently available at the pump).

The anti-knock index that prevents 'pinging' in a given engine has nothing to do with the formulation of that fuel as far as burn speed and such.

Still, the kdx static compression ratio is quite conservative. Someone that knows how to modify squish bands and angles correctly during a head machining process could likely benefit your bike's power output.

Horsepower and torque.

Negative effects? Not if it's done right. If wrong (from the 'more is better' crowd), then there's quite a list of negative effects.

 

[Kawadougie]

This was originally posted in the Mods & Performance Forum but one of the moderators decided it belongs here just because of the bike I own. I was hoping to hear from Eric Gorr and others on the subject but I guess I just don't need to, right? I don't agree with anything you said about modifying an engine to fit the fuel you are running but hey, that's your opinion and mine is different. My bike runs better, cleaner and cooler with race gas than with the crap they have at the pump today and I want to take advantage of the fact that higher octane enables higher compression to deliver more horsepower. Simple as that.

 

[canyncarvr]

Click on EGs ad. Go to his site. Read RRs input on basic fuel theory.

I didn't state an opinion. It's a fact.

'My bike runs better, cleaner and cooler with race gas...' That being so, is a perfect example of what I said. Although, please do consider the 'better...cooler' part. Heat is power. All other things being equal, a reduction in heat production does not equate to a good thing.

Another opinion.

In the end, whatever suits you should tickle everyone else. (Doesn't necessarily have to have anything to do with facts. Pesky little buggers anyway!!)