compression
05-04-2001, 12:31 PM
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compression
well i gotta quick qestion can i lower my compression ratio wit just a head gasket? is that all i need to lower the compression. cause im reading the new turbo mag and this company called inline pro said their headgaskets are lowering compression ratios to 9:1. and with a AFC running 10-22 pounds of boost on stock honda b18c motors. any opinions on this claim right here?
05-04-2001, 07:36 PM
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Tone-
You need to re-read some of red's posts on turbo's and compression. or go to http://www.theoldone.com/ and read some of their posts.
If you have a perfect engine, you can run a 15:1 compression ratio and 30 PSI of boost. It's all about how the head is designed, how it flows, how the combustion chamber is shaped, and how the pistions are shaped. (plus the materials..etc...etc...etc..).
There is MUCH more knowledge in the honda camp, as to How to run big boost with high compression ratio's than there is in the Hyundai Camp. That now said. Red is trying to build up a 15PSI 10:1 (or there abouts) turbo motor.
What I'm trying to say here, is that i's more about detonation due to poor design, than just simply the compression ratio.
yes, you can get a head gasket spacer from Alpine technologies that will lower your compression ratio to 8.5:1 (assuming they will sell it seperatly). Yes, it will lower your compression, and in general, lower compression with forced induction is safer. BUT...High compression is where the big power is. But for most people, it's easier to add 3-5 PSI of boost than to re-work their combustion chamber/head/pistions....
You need to re-read some of red's posts on turbo's and compression. or go to http://www.theoldone.com/ and read some of their posts.
If you have a perfect engine, you can run a 15:1 compression ratio and 30 PSI of boost. It's all about how the head is designed, how it flows, how the combustion chamber is shaped, and how the pistions are shaped. (plus the materials..etc...etc...etc..).
There is MUCH more knowledge in the honda camp, as to How to run big boost with high compression ratio's than there is in the Hyundai Camp. That now said. Red is trying to build up a 15PSI 10:1 (or there abouts) turbo motor.
What I'm trying to say here, is that i's more about detonation due to poor design, than just simply the compression ratio.
yes, you can get a head gasket spacer from Alpine technologies that will lower your compression ratio to 8.5:1 (assuming they will sell it seperatly). Yes, it will lower your compression, and in general, lower compression with forced induction is safer. BUT...High compression is where the big power is. But for most people, it's easier to add 3-5 PSI of boost than to re-work their combustion chamber/head/pistions....
05-04-2001, 10:44 PM
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cool. aiight but what do you mean by the perfect engine??? speaking about the Beta engine. and i thought the power came from lower compression and high boost instead of high compression and high boost?? im going to check out Reds post on compression and turbo. cause you know im making this turbokit and if i can find an engine rebuilt the engine buti want to do it right the first time..lol.
i kknow some of these questions are stupid but im not an engine guru like you guys im learning something new everyday.
i kknow some of these questions are stupid but im not an engine guru like you guys im learning something new everyday.
05-05-2001, 05:40 PM
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Power is made by high compression. Forced induction is about high compression.
you are FORCING 10 PSI of air into the cylinder. Then the Cylinder compresses that air. This RAISES the compression ratio.
Think about it. You have an engine that has 10:1 compression ratio. You then FORCE 10 PSI of air into the cylinder. You just RAISED the effective compression ratio of the engine.
The reason most turbo cars are around 8 to 8.5:1 is becuase of the above. On boost, they are running about 12:1 compression (depending on the amount of boost). If you have a 10:1 compression ratio engine, at the same boost levels you would be up to 14:1 or 15:1 compression ratio. The higher the compression ratio, the more detnotation becomes a problem. The higher the compression ratio, the HOTER that compressed gas is (All things heat when you compress them), also the closer those air and fuel molocules are to eachother. All it needs is a little hot spot to ignite one area of the combustion chamber and BOOM the whole chamber goes up early...and you have detnotation...and a chunked motor.
http://www.topgear.co.za/alpine-developmen...ents/index.html
you are FORCING 10 PSI of air into the cylinder. Then the Cylinder compresses that air. This RAISES the compression ratio.
Think about it. You have an engine that has 10:1 compression ratio. You then FORCE 10 PSI of air into the cylinder. You just RAISED the effective compression ratio of the engine.
The reason most turbo cars are around 8 to 8.5:1 is becuase of the above. On boost, they are running about 12:1 compression (depending on the amount of boost). If you have a 10:1 compression ratio engine, at the same boost levels you would be up to 14:1 or 15:1 compression ratio. The higher the compression ratio, the more detnotation becomes a problem. The higher the compression ratio, the HOTER that compressed gas is (All things heat when you compress them), also the closer those air and fuel molocules are to eachother. All it needs is a little hot spot to ignite one area of the combustion chamber and BOOM the whole chamber goes up early...and you have detnotation...and a chunked motor.
http://www.topgear.co.za/alpine-developmen...ents/index.html
05-05-2001, 10:37 PM
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so do you think i should lower my compression or not?? i mean i know there is ways to avoid detonation at high compression. i just emailed onpol about his set up since mine is the exact same set up. but iwant to try to get a little more power than onpol. he pulled 227whp without upgrading anything except the fuel pump and injectors and of course AFC.
05-06-2001, 02:20 AM
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He got that with only 10 PSI of boost. There's still plenty more HP in his turbo setup.
But you've got a 1.8L. To get the same HP you'll need more boost. Your best bet to stop detonation at high boost levels, but keep your HP up would be water injection or Methanal injection.
But you've got a 1.8L. To get the same HP you'll need more boost. Your best bet to stop detonation at high boost levels, but keep your HP up would be water injection or Methanal injection.
05-06-2001, 03:21 AM
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yeah i was about to mention that water injection kit. we talked about that before. well i knowim just a lowly 1.8L but if my money is right ill be looking for a 2.0 around Xmas time. well i still have my other elantra( my wifes drives it but i pay the note and insurance and its in my name 
)
the 2000 with a 2.0 140HP but ill just go with a old ass 2.0 with about 80,000 and rebuild it. but yeah its the same set that onpol has and word is that he is going for a bigger turbo and injectors and a haltec.
)the 2000 with a 2.0 140HP but ill just go with a old ass 2.0 with about 80,000 and rebuild it. but yeah its the same set that onpol has and word is that he is going for a bigger turbo and injectors and a haltec.
05-06-2001, 04:20 AM
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Usually turbo kits come with a spacer (metal not your usual gasket) when the stock compression is too high. Tiburon has a very high compression for a regular production vehicle so the gasket is thicker than the original gasket and therefore increases the size or the combustion chamber. This is to avoid detonation. It all depends on what you are looking for but Alpines (not sure available for US)I like because it is kind of independent set from the original ECU and inyectors. Instead they to extra fueling though a 5th inyector connected to your intake manifold and an independent fueler box takes care of the the high demand under high rev and high boost, otherwise your original system takes care of fueling. This way you do not need larger injectors, expensive new ECU and others.
There are many factors that does not allow you to go high comp and high boost commented by Random. But for street use I recommend lowering compression to 9.0, get a HKS EVC which allows you to control the wastegate from the cockpit so if your original boost level is say 10 psi you can go higher up to 14-16 psi (alpine rates 230hp at 10psi) so a couple of more psi will get you more power. The secret is to avoid detonation as you go higher boost which has a lot to do among other by high temp of mix and quality of fuel. Things to do:
1) Intercool
2) Heat wrap exhaust and intake
3) Use a CAI that breathes from cool outside air.
4) Use high quality fuel (octane and boosters)
5) Any cooling ideas like water injection into your intake, methanol (never seen it) and other ideas like Randoms Intercooling water mist cooling.
Beware of size of turbo, this is quite technical matter which I would not advice you to do by yourself unless you have the knowledge to select. There are pump charts you have to work with etc. etc.
There are many factors that does not allow you to go high comp and high boost commented by Random. But for street use I recommend lowering compression to 9.0, get a HKS EVC which allows you to control the wastegate from the cockpit so if your original boost level is say 10 psi you can go higher up to 14-16 psi (alpine rates 230hp at 10psi) so a couple of more psi will get you more power. The secret is to avoid detonation as you go higher boost which has a lot to do among other by high temp of mix and quality of fuel. Things to do:
1) Intercool
2) Heat wrap exhaust and intake
3) Use a CAI that breathes from cool outside air.
4) Use high quality fuel (octane and boosters)
5) Any cooling ideas like water injection into your intake, methanol (never seen it) and other ideas like Randoms Intercooling water mist cooling.
Beware of size of turbo, this is quite technical matter which I would not advice you to do by yourself unless you have the knowledge to select. There are pump charts you have to work with etc. etc.
05-06-2001, 06:38 AM
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yeah i was thinking about the T3 the T3/T4 hybrid or the 17g turbocharger. most likely ill get the T3 and after i get the boost and everything else straight ill upgrade the turbo.
