APEXi S-AFC?
05-27-2002, 02:57 AM
#16
Race Director
Hmmm, apparently the DME still considers the air-flow signal since one can adust the air-fuel ratio at full-throttle/high-RPM with the ARC2. I was fiddling with it to troubleshoot a stumbling engine after I fitted a new muffler.
This is also indicated by the changes required in going from 15psi to 18psi of boost. Ideal air-fuel ratios at full-throttle/high-RPM at 15psi ends up being too lean at 18psi. However, this can be remedied by adjustments using the ARC2 only.
Anyway, there shouldn't be any functional difference between the S-AFC and the AFM-Link. Both intercept (or simulate it in the AFM-Link) the air-flow signal and pass it on to the DME. Haven't looked too closely at the S-AFC, but the AFM-Link has a neat feature of being programmable with its own little hand-held display, or with a laptop-PC.
We'll know by next weekend how Travis's AFM-link MAP conversion goes...
This is also indicated by the changes required in going from 15psi to 18psi of boost. Ideal air-fuel ratios at full-throttle/high-RPM at 15psi ends up being too lean at 18psi. However, this can be remedied by adjustments using the ARC2 only.
Anyway, there shouldn't be any functional difference between the S-AFC and the AFM-Link. Both intercept (or simulate it in the AFM-Link) the air-flow signal and pass it on to the DME. Haven't looked too closely at the S-AFC, but the AFM-Link has a neat feature of being programmable with its own little hand-held display, or with a laptop-PC.
We'll know by next weekend how Travis's AFM-link MAP conversion goes...
05-28-2002, 07:42 PM
#17
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On one of my buddy's turbo 240SX, we swapped the engine over a weekend, and dyno-tuned it perfectly on Monday in less than one hour with the Apexi S-AFC. With only three dyno runs we got 325rwhp @ 15psi from 2.0ltr.
What was the engine making before the Apexi was put on and tweaked? <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" />
What was the engine making before the Apexi was put on and tweaked? <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" />
05-29-2002, 03:49 AM
#18
Race Director
He used the standard SR20-DET S14 engine swap for the 240SX. This is a Japan-only 2.0l 4-cyl. engine used in the '99+ Silvia and gets 250bhp in stock trim.
"What was the engine making before the Apexi was put on and tweaked?"
By themselves, piggyback signal-massagers won't do a thing for your car. Kinda like adding chips without raising the boost. They just allow you to obtain an optimal air-fuel ratio when you DO add air-flow increasing upgrades.
Then the usual upgrades to larger T4 turbo, larger MAF and injectors, 3" exhaust, allows doubling of the stock boost. Since the engine wasn't upgraded tremendously, the stock computers could be used with a piggyback signal massagers to change the shape of the fuel-curve.
In this case, the adjustments are similar to the 951's Autothority Stg.2 problems with a super-rich mid-range and a lean top-end. So dialing in the FPR to allow an ideal high-RPM/full-load mixture with zero-corrections, the S-AFC was used to dial back the fuel in the mid-range and idle settings.
Since this engine has 4-valve heads with variable-cam timing, it didn't exhibit the tremendous high-RPM torque drop-off ones sees with modified 951s. As such, maximum power was achieved near redline without a dropping power-curve as well.
"What was the engine making before the Apexi was put on and tweaked?"
By themselves, piggyback signal-massagers won't do a thing for your car. Kinda like adding chips without raising the boost. They just allow you to obtain an optimal air-fuel ratio when you DO add air-flow increasing upgrades.
Then the usual upgrades to larger T4 turbo, larger MAF and injectors, 3" exhaust, allows doubling of the stock boost. Since the engine wasn't upgraded tremendously, the stock computers could be used with a piggyback signal massagers to change the shape of the fuel-curve.
In this case, the adjustments are similar to the 951's Autothority Stg.2 problems with a super-rich mid-range and a lean top-end. So dialing in the FPR to allow an ideal high-RPM/full-load mixture with zero-corrections, the S-AFC was used to dial back the fuel in the mid-range and idle settings.
Since this engine has 4-valve heads with variable-cam timing, it didn't exhibit the tremendous high-RPM torque drop-off ones sees with modified 951s. As such, maximum power was achieved near redline without a dropping power-curve as well.
05-29-2002, 06:35 AM
#19
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A company called <a href="http://www.dpmotorsport.com" target="_blank">DP Motorsport</a> in the UK have used the Apexi stuff on 951s. There was an article in 911&PW a while ago about one of their cars. I think the guy who runs it has raced a few Porsches, but there isn't anything Porsche specific on their site. Anyone got the article to scan?
06-07-2002, 04:24 AM
#20
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Gabe had that article. I read it, but it was worthless as far as useful modifications info. Just basically, "we did this, then that, or was it the other thing?" You can get more info about the S-AFC from reading this board.
06-07-2002, 10:05 AM
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[quote]Originally posted by Danno:
<strong>Gabe had that article. I read it, but it was worthless as far as useful modifications info. Just basically, "we did this, then that, or was it the other thing?" You can get more info about the S-AFC from reading this board.</strong><hr></blockquote>
I just meant that the guy may be useful to speak to via email as he has first hand experience of using the Apexi stuff on a 951.
<strong>Gabe had that article. I read it, but it was worthless as far as useful modifications info. Just basically, "we did this, then that, or was it the other thing?" You can get more info about the S-AFC from reading this board.</strong><hr></blockquote>
I just meant that the guy may be useful to speak to via email as he has first hand experience of using the Apexi stuff on a 951.
