Why not higher compression ratio??
- Thread starter Boss302
- Start date
The reason Diesel's engine uses glow plugs is that only vapors burn, not liquids. And diesel fuel is harder to vaporize. Needs more heat.Junior said:
that and that it wont combust at all if it doesn't get to flash point.
direct injection is done outside just diesels too. Lots of outboard motors have it, it's becoming very commonplace in 2-strokes.
direct injection is done outside just diesels too. Lots of outboard motors have it, it's becoming very commonplace in 2-strokes.
A few years ago everybody kept recommending to lower your compression. That way you were able to run more boost safely, and get more power. Now I'm hearing about guys running 10-11:1 running 25+psi of boost. "It's all in the tune", they say. So with higher compression would there be a need to run alot (25+) of boost?
Lots of the new Audis use direct injection, including the new RS and S engines.
Direct injection... The future of the gasoline combustion engine.
Direct injection... The future of the gasoline combustion engine.
Also, these still use spark ignition, they are not compression ignition like a Diesel. And the main advantage is under very light load when they run super lean. At high load they are not much different from regular injection (both inject on the intake stroke).
Yeah, the new GR motors from Toyota are direct injected...I have higher than GTE Comp. ...its called a GE shortblock!
Suprapowaz!(2) said:
it's a trade off LOTTA boost little compression. LOTTA compresion little boost LOTTA of both and boom i would like to see how many seconds a turbo'd motor with high compression wouldn't Last it would work fine make mosterous power but would but it wouldn't last why do you think Formula 1 dragsters have to rebiuld the engine EVERY race.
Adjuster
Supramania Contributor
Too bad that Audi has not decided to bring the excellent turbo diesels they sell in Europe here to the States. (They have V8 and V10 twin turbo versions that have excellent tourqe and drive quite nice.)
The V10 did come over for a brief time in the Toureg, but nobody here bought them, and they stopped building them for this market. (Great news is a few hundred are here, and the used prices should be falling soon, so it will be time to pickup a Diesel Toureg for my Wife one of these days... LOL and convert it to run on used fry oil... LOL )
The FSI direct injection on the R8's was totally reliable, and as they proved, kicked ass in racing. (They pretty much won everything they entered.)
For a turbo engine, this is totally the way to go. You can compress the living daylight out of the intake charge because it's only air. There is no fuel added untill the computer decides to add it. (Just like a diesel.) Think about this for a second too. On a normal fuel injected setup, some of the displacement is used up by fuel... So by removing the fuel, you instantly take the same "size" motor and make it slightly more powerful just from that fact that there are more air molecules in the chamber taking up space where fuel would normally be. Compress this, and it get's even more interesting. Put in your 500f temp air at 40psi... The engine does not care. There is no fuel to burn yet. Then right as the piston get's to the right point in the process, the fuel is introduced and the spark is right after it. (Of course, at this high of a charge temp, the spark is really not needed... The fuel lights off just from the heated air alone, and you keep adding fuel as the mixture burns... and the piston is forced down as the burning fuel and air expand... No detonation, no chance for pre-ignition and the pressures you could work with are way over what we have come to expect from gas turbo charged engines.)
Also as noted, under light load conditions, you can run very lean, and since your adding the fuel right at the point where the plug is located, the local "rich" spot there allows the lean mix to light off, and you have good lean burn with very little left over hydrocarbons. (Good for even the crazy state of CA.)
What Audi needs to do is sell me a twin turbo V10 FSI engine that runs 25:1 at cruise, and under boost makes a nice 800 AWHP
Mmmmm. 30+mpg fuel economy, and in a car that will haul the family around in comfort, and still put down a nice 12 sec. quarter mile or better.
The V10 did come over for a brief time in the Toureg, but nobody here bought them, and they stopped building them for this market. (Great news is a few hundred are here, and the used prices should be falling soon, so it will be time to pickup a Diesel Toureg for my Wife one of these days... LOL and convert it to run on used fry oil... LOL )
The FSI direct injection on the R8's was totally reliable, and as they proved, kicked ass in racing. (They pretty much won everything they entered.)
For a turbo engine, this is totally the way to go. You can compress the living daylight out of the intake charge because it's only air. There is no fuel added untill the computer decides to add it. (Just like a diesel.) Think about this for a second too. On a normal fuel injected setup, some of the displacement is used up by fuel... So by removing the fuel, you instantly take the same "size" motor and make it slightly more powerful just from that fact that there are more air molecules in the chamber taking up space where fuel would normally be. Compress this, and it get's even more interesting. Put in your 500f temp air at 40psi... The engine does not care. There is no fuel to burn yet. Then right as the piston get's to the right point in the process, the fuel is introduced and the spark is right after it. (Of course, at this high of a charge temp, the spark is really not needed... The fuel lights off just from the heated air alone, and you keep adding fuel as the mixture burns... and the piston is forced down as the burning fuel and air expand... No detonation, no chance for pre-ignition and the pressures you could work with are way over what we have come to expect from gas turbo charged engines.)
Also as noted, under light load conditions, you can run very lean, and since your adding the fuel right at the point where the plug is located, the local "rich" spot there allows the lean mix to light off, and you have good lean burn with very little left over hydrocarbons. (Good for even the crazy state of CA.)
What Audi needs to do is sell me a twin turbo V10 FSI engine that runs 25:1 at cruise, and under boost makes a nice 800 AWHP
Mmmmm. 30+mpg fuel economy, and in a car that will haul the family around in comfort, and still put down a nice 12 sec. quarter mile or better.
Suprapowaz!(2) said:
I've never heard of anything that extreme. I was running 9.7:1 on stock boost. No problems.
When my car's back together I'm gonna shoot for 9.4:1 and 12 psi. There's a few people that have 9:1 pistons or GE shortblocks that run significant boost.
Adjuster, under max load I believe it is not possible to operate in the stratified charge method where injection occurs immediately before ignition. Instead, the charge is loaded thoughout the intake stroke to allow for a uniform A/F throughout the combustion chamber.