6.97@197mph Sporty Motorsports 13B RX7
11-20-08, 12:58 PM
#226
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I think I understand this better now. When you increase your compression in a conventional way, you decrease the volume at TDC, which will give you more torque, but does not do anything to actually increase the mass of air in the chamber. Forced induction would be more like increasing your total compression ratio by increasing the volume at BDC, which would get you more air into the chamber.
So why is it that NA engines will have detonation issues with higher compression ratios (say 15:1), but my Impreza can boost 15 psi (2:1) and then compress that fluid an additional 8:1? That’s a total compression ratio of 16:1 as far as the fluid is concerned. Is this because in the case of a turbo motor you have the ability to cool the air in between compression stages, but on a high compression ratio NA motor, you cannot cool the charge in the middle of the compression stroke (except maybe by using a phase transformation of water or methanol or gasoline).
So why is it that NA engines will have detonation issues with higher compression ratios (say 15:1), but my Impreza can boost 15 psi (2:1) and then compress that fluid an additional 8:1? That’s a total compression ratio of 16:1 as far as the fluid is concerned. Is this because in the case of a turbo motor you have the ability to cool the air in between compression stages, but on a high compression ratio NA motor, you cannot cool the charge in the middle of the compression stroke (except maybe by using a phase transformation of water or methanol or gasoline).
11-20-08, 01:30 PM
#227
'Tuna'
Thread Starter
I think I understand this better now. When you increase your compression in a conventional way, you decrease the volume at TDC, which will give you more torque, but does not do anything to actually increase the mass of air in the chamber. Forced induction would be more like increasing your total compression ratio by increasing the volume at BDC, which would get you more air into the chamber.
So why is it that NA engines will have detonation issues with higher compression ratios (say 15:1), but my Impreza can boost 15 psi (2:1) and then compress that fluid an additional 8:1? That’s a total compression ratio of 16:1 as far as the fluid is concerned. Is this because in the case of a turbo motor you have the ability to cool the air in between compression stages, but on a high compression ratio NA motor, you cannot cool the charge in the middle of the compression stroke (except maybe by using a phase transformation of water or methanol or gasoline).
So why is it that NA engines will have detonation issues with higher compression ratios (say 15:1), but my Impreza can boost 15 psi (2:1) and then compress that fluid an additional 8:1? That’s a total compression ratio of 16:1 as far as the fluid is concerned. Is this because in the case of a turbo motor you have the ability to cool the air in between compression stages, but on a high compression ratio NA motor, you cannot cool the charge in the middle of the compression stroke (except maybe by using a phase transformation of water or methanol or gasoline).
11-20-08, 02:31 PM
#229
'Tuna'
Thread Starter
12-03-08, 08:49 AM
#232
Banned. I got OWNED!!!
Join Date: Apr 2008
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I am good friends with Pete though, maybe his humour and language is rubbing off on me
