Nitrous Oxide 944 Turbo
12-11-2002 | 12:11 PM
#31
Racer
Joined: Sep 2002
Posts: 313
Likes: 0
From: Victoria, BC, Canada
[quote]Originally posted by BigPorscheGuy39:
less chance of spurious, random detonations.<hr></blockquote>
Correct me if I'm wrong, but when the piston is coming up and pressurizing the combustion chamber, this is when detonation happens. The combustion gases/fuel explode before they're supposed to and cause the familiar 'pinging' With denser gases, ie: a colder intake charge, this is more likely because the denser air is being crammed into a small space.
I think things like I mentioned: "head gasket roasting" are caused by excess heat or a very lean condition. So I was incorrect in this case because the cooling of the intake charge would actually help this.
In any case, moving up a few octane points or slightly lowering the boost would help this.
less chance of spurious, random detonations.<hr></blockquote>
Correct me if I'm wrong, but when the piston is coming up and pressurizing the combustion chamber, this is when detonation happens. The combustion gases/fuel explode before they're supposed to and cause the familiar 'pinging' With denser gases, ie: a colder intake charge, this is more likely because the denser air is being crammed into a small space.
I think things like I mentioned: "head gasket roasting" are caused by excess heat or a very lean condition. So I was incorrect in this case because the cooling of the intake charge would actually help this.
In any case, moving up a few octane points or slightly lowering the boost would help this.
12-11-2002 | 08:00 PM
#32
Banned
Joined: Jun 2001
Posts: 776
Likes: 0
From: Waterloo, ON
Hey Kieth! You said "Correct me if I'm wrong, but when the piston is coming up and pressurizing the combustion chamber, this is when detonation happens."
I've never investigated it in depth so I'm not really sure! I always thought the frequency of detonations would be distributed sort of bimodally (one bump before the top of stroke, one bump afterwards) around the top most part of the upstroke, but also some detonations trailing off as the piston moves past top on the way down. But again, I'm just guessing. What you're saying makes sense somehow: The biggest bump (time for most detonations) should be on the upstroke.
Yeah, you know, I'm just thinking now about you and me trying to figure out the nuances of how even something 'simple' like detonation happens, and we're not necessarily stupid people, and how challenging and detailed a job it is to figure out the way things work. You really have to understand the physics and the chemistry of engines before you can be confident of what you're doing.
In contrast, I'm reminded of the speed shops and performance places that hock nitrous to guys who are way more ignorant than you and me! And I'm astounded at how these shops are really playing into a huge need that exists out there for speed! Pity there wasn't a course on it so guys would have a better idea of what they're getting into before the hook up the bottle and go BOOM.
I've never investigated it in depth so I'm not really sure! I always thought the frequency of detonations would be distributed sort of bimodally (one bump before the top of stroke, one bump afterwards) around the top most part of the upstroke, but also some detonations trailing off as the piston moves past top on the way down. But again, I'm just guessing. What you're saying makes sense somehow: The biggest bump (time for most detonations) should be on the upstroke.
Yeah, you know, I'm just thinking now about you and me trying to figure out the nuances of how even something 'simple' like detonation happens, and we're not necessarily stupid people, and how challenging and detailed a job it is to figure out the way things work. You really have to understand the physics and the chemistry of engines before you can be confident of what you're doing.
In contrast, I'm reminded of the speed shops and performance places that hock nitrous to guys who are way more ignorant than you and me! And I'm astounded at how these shops are really playing into a huge need that exists out there for speed! Pity there wasn't a course on it so guys would have a better idea of what they're getting into before the hook up the bottle and go BOOM.
12-12-2002 | 12:12 PM
#33
Racer
Joined: Sep 2002
Posts: 313
Likes: 0
From: Victoria, BC, Canada
Yes, what you've said is very true! What we're talking about is very complicated and what actually goes on when you put your foot down is very complicated. There's lots of guys pumping out big bucks to put "NAWWWS" on their cars only to need a new engine after a few thousand miles. Personally, I love the daily no-hassle drivability of the 944 Turbo - a truly awsome car!
But that's one thing about the 944 Turbo; it's complicated enough to put 300+ HP on pavement with a 2.5L but still simple enough for us to sort-of understand and throw a few well educated mods at it!
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> <img src="graemlins/xyxwave.gif" border="0" alt="[bigbye]" /> <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />
But that's one thing about the 944 Turbo; it's complicated enough to put 300+ HP on pavement with a 2.5L but still simple enough for us to sort-of understand and throw a few well educated mods at it!
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> <img src="graemlins/xyxwave.gif" border="0" alt="[bigbye]" /> <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />
