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I bet NOBODY knows the answer to this question....

 
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emoore924  



Joined: 13 Apr 2004
Posts: 2797

PostPosted: Sat Jan 13, 2007 4:40 am    Post subject: I bet NOBODY knows the answer to this question.... Reply with quote

What's the volumetric efficiency of the 1980 924 turbo engine in stock configuration (no head work)...?? No speculation, just facts please.

Oh, and if you could include your source, that would be great.
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Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11378
Location: PacNW

PostPosted: Sat Jan 13, 2007 5:49 am    Post subject: Reply with quote

If you're thinking, "wtf is that," here's the definition.
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flosho  



Joined: 01 Jul 2004
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PostPosted: Sat Jan 13, 2007 6:06 am    Post subject: Reply with quote

80%

http://www.924board.org/viewtopic.php?t=16512&highlight=volumetric+efficiency

http://www.stealth316.com/2-air-fuel-flow.htm

This thread: http://www.924board.org/viewtopic.php?t=5434&highlight=volumetric+efficiency

I take this quote:

Richard wrote:
Geddy T, Thanks for the reality check. I am well aware of the complications of making an engine. A friend of mine has been trying to make and engine from scratch for a Beloit Indianapolis racer from the 1920's I think. Been at it for years. There are companies that will design heads for your special project, but like you said, ante up the $$$. That is why I'm most interested with working with the stock or turbo head and realigning the ports for better velocity. I really don't think larger valves or hogging out the ports is the answer, except for full out race gear. As Peter said many months ago, the engine already flows enough for it's size. My hunch is that same size or smaller ports, but with different shape, will speed up the flow. Also getting away from the stock fuel injection opens up a whole lot of possibilities. I believe the guys with carbs are getting 10 or more hp, some of which is due to richer ratio, but also because the air doesn't have to turn so much. I am interested in looking at an early head with D shaped port. Lots on the net about the virtues of D ports(flat floor). Maybe something to it? Not against looking at different heads though, but then you have to remake the pistons cause of the loss of CR. I did a dyno 2000 on this engine stock and the volumetric efficiency stinks. It gets as high as 83.2% at 5500 rpm. At 3500 midrange it is 78%. Modern cengines, I believe, get as high as 90 or more with impulse tuning. This is what needs to be adressed IMHO. For me, the less money the better.

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emoore924  



Joined: 13 Apr 2004
Posts: 2797

PostPosted: Sat Jan 13, 2007 9:24 am    Post subject: Reply with quote

Thanks very much for the responses.

Yeah, 80% is about what I thought at first. But when I looked at the map for a K26 2470 G6.10, I had to use 95% in my configuration calculations to back into the flow figures for the respective RPMs on the map -- and that's straight from KKK using the 2.0l 924 motor but the 2470 turbo (closest thing to a match that I could find).

I know the K26 2470 G6.10 turbo is a little different that the K26 2660 GA6.10 I'm sizing for, but shouldn't the kg3/sec flows at least be in the ballpark if I use the numbers from the 2470 -- and I just can't get from my calculations to the chart without using 95% VE. At 80% I'm way low. Maybe the maps are really different but 15%? That's a lot.

I'd love to find a compressor map for the 2660 but KKK turbo maps are like hen's teeth, they just aren't around. In lieu of that, I'd settle for some dyno work or something someone's done with VE on the turbo specifically, to get me the kg3/sec numbers I need to match on the map.

I know the VE % for a n/a car can be pretty low. But I also thought the %'s for the turbo could approach 100% if the turbo was spooled up and the head/manifold/valves were right...
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