clint78z Posted August 7, 2002 Share Posted August 7, 2002 here is another good one, Compression, what the heck does compression have to do with all this, and combustion chamber size. I did a little off the norm for these engines. I upped the static compression on my engine, and you know it worked out very well for me. A similar setup to what I have takes 6 more psi to develop the same power. Combustion chamber, there again, you will be able to fill more air and fuel if it is bigger. Okay - the compression ratio is what determines the combustion efficiency of your engine (i.e., how much power you get by burning a given amount of fuel). Higher compression ratios are more efficient. The problem is that higher compression ratios also result in a higher temperature rise as the fuel/air mix is compressed. If you go too high with the CR, the temperature of the fuel/air mix will get high enough for it to ignite, causing detonation. Interestingly, if you look into the thermodynamic equations for the Otto cycle, you'll find that the amount of temperature rise is dependant ONLY on the Compression Ratio, hence the final temperature at TDC is determined by the temperature of the air at the beginning of the cycle, and the CR of the engine. Contrary to popular belief, it is not dependant on the pressure that you start at. Read that a couple of times before shouting that I'm full of sh!t . The problem that turbocharging adds is not the pressure, but the fact that it tends to increase the starting temperature of the combustion cycle. Okay - well I thought it was interesting, anyway. As far as the combustion chamber size thing - do you mean displacement, rather than combustion chamber size? They are two different things. Larger displacement will do the stuff you mentioned re: getting more air/fuel in. However, a larger combustion chamber by itself will only result in a lower compression ratio. While this will give you more resistance to detonation for the reasons stated above, it does not cause more air/fuel to get pulled in.[/QB] TimZ you are so full of it your eyes are brown Good discussion and TimZ is absolutely correct about the Otto cycle. T1 [V2]n-1 __= [__] T2 [V1] The point I was trying to make about max boost and rpm TimZ explained better. The easiest units to work with when doing complete systems like this, think mass flow (it never changes unless you motor is capable of destroying mass )I always start with mass at the air filter and that way you can check later on in the system if your volume calc's are correct. Gone are the days of big turbo huge lag, with a good amount of research you can have your cake and eat it too. Quote Link to comment Share on other sites More sharing options...
scottyMIz Posted August 7, 2002 Share Posted August 7, 2002 Ok guys i didn't want to post a whole new message about this and i saw you guys where talking about it on here.How do i know what trim i have on my turbine wheel?I know my a/r for the compressor housing is .70 but i don't know the trim and i'd like to know more about my turbo.All this talk about maps and stuff makes me very curious to learn more.I'd like to know where the "sweet spot" is for it and anything else i can learn about it.Thanks guys Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted August 7, 2002 Share Posted August 7, 2002 For the record, James, I am not talking about Walker. In fact, speaking of Walker, he recommended the stage V wheel to me when I saw him in May. We had some discussion about turbo's and such, and I expect he has learned some more info since getting into the DSM crowd. I do not recall though if he recommended the stage V wheel versus the wheel he ran in that funky turbo he made. I never was sure if he had a P trim, or if it was some wheel from a Komatsu or what it was. I don't want to trash someone's business on this open forum, yet, but suffice to say, I am not going to do business with a turbo shop when I have very good info from people I trust that their work lacks quality control. If anyone would like to know to whom I am referring, send me a personal email and I will tell you. But I am not going to trash them out here. Now if I bought something from them and it breaks, that is another story. Man I just want to go fast, why is it so difficult? Quote Link to comment Share on other sites More sharing options...
Sean 83ZXT Posted August 7, 2002 Share Posted August 7, 2002 If you're looking for a good Turbo company check out Innovative Turbo Solutions. Some of the main guys founded Turbonetics back in the hay day. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted August 7, 2002 Share Posted August 7, 2002 I guess I fianlly have something to add here. TimZ was talking about a swing valve in the turbine housing. Right? Anyway I think that the second generation RX-7's had something like this on their cars. If you could controll this smoothly it seems like it would really answer a few questions. Welcome Jeffp. Glad to see you fianlly found this board. It's seems to have better info then some of the other boards out there. Quote Link to comment Share on other sites More sharing options...
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