'88 5-speed dyno log
03-14-2013, 04:55 PM
#61
Three Wheelin'
I'd like to ask that question again. Why cant the S3 breathe at high rpm? I know if Ken could make the S3 breathe better he would have already, with the exception of the torque rings (which I have installed). Just curious as to what or where the restriction is...?
03-14-2013, 06:00 PM
#63
Rennlist Member
Yes, they do run at high duty cycles, in the 90's at max power. In the 928 they are run at higher than rated fuel pressure for their 19# rating, so in fact they are behaving more like 24#.
It's debatable whether it is a problem in practice to run near "on all the time" with the power levels likely to be achieved from S4/GT/GTS in stock trim. And that's the market Ken's chips are aimed at.
Porsche didn't give much power away at the top end, they didn't need the huge ignition safety margin they had to use on the S2/S3 which have no knock control system. There are however very useful gains to be made in the mid range on the S4 and later.
It's debatable whether it is a problem in practice to run near "on all the time" with the power levels likely to be achieved from S4/GT/GTS in stock trim. And that's the market Ken's chips are aimed at.
Porsche didn't give much power away at the top end, they didn't need the huge ignition safety margin they had to use on the S2/S3 which have no knock control system. There are however very useful gains to be made in the mid range on the S4 and later.
Has anyone else seen 19 lb injectors at 90% duty cycle on a stock S-4 engine?
John Speake?
I've run 19 lb. injectors in a stroker, before, and made 330 RWHP. I did this with Shawn Smith's engine, during my R&D stage.
That's what is so confusing about what Ken is saying.
John Speake?
I've run 19 lb. injectors in a stroker, before, and made 330 RWHP. I did this with Shawn Smith's engine, during my R&D stage.
That's what is so confusing about what Ken is saying.
03-14-2013, 06:39 PM
#64
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Tom:
I believe that's a picture of an intake and an exhaust from an S4, not an S3 intake and an S4 intake. The difference isn't that severe.
I believe that's a picture of an intake and an exhaust from an S4, not an S3 intake and an S4 intake. The difference isn't that severe.
__________________
greg brown
714 879 9072
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Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
03-14-2013, 06:41 PM
#65
Rennlist
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Yes, they do run at high duty cycles, in the 90's at max power. In the 928 they are run at higher than rated fuel pressure for their 19# rating, so in fact they are behaving more like 24#.
It's debatable whether it is a problem in practice to run near "on all the time" with the power levels likely to be achieved from S4/GT/GTS in stock trim. And that's the market Ken's chips are aimed at.
Porsche didn't give much power away at the top end, they didn't need the huge ignition safety margin they had to use on the S2/S3 which have no knock control system. There are however very useful gains to be made in the mid range on the S4 and later.
It's debatable whether it is a problem in practice to run near "on all the time" with the power levels likely to be achieved from S4/GT/GTS in stock trim. And that's the market Ken's chips are aimed at.
Porsche didn't give much power away at the top end, they didn't need the huge ignition safety margin they had to use on the S2/S3 which have no knock control system. There are however very useful gains to be made in the mid range on the S4 and later.
With the additional power, they must be running near 100%?
03-14-2013, 06:58 PM
#66
03-14-2013, 07:19 PM
#67
Rennlist Member
Yes, they are pretty much at 100%. Some of that % will be taken up with the over-rich mixture that Porsche always puts in there as a safety margin for aged MAFs etc.
03-14-2013, 09:19 PM
#68
Inventor
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Thread Starter
Even with HIR turned on, I'm hitting 90% duty at 6300 RPM/12.5 AFR, with 24# injectors.
Half Injection Rate only knocks off a few percent duty cycle.
When HIR kicks in, (over 5100 RPM stock) the injectors are firing only once per rev, but the injectors are staying open longer to compensate.
Unfortunately, miscalculations are amplified by HIR, so it can get some really high spikes of rich/lean.
Porsche did about as good as they could with the stock maps.
There isn't a great deal more to get with the available 16x16 maps, the way they are arranged.
Half Injection Rate only knocks off a few percent duty cycle.
When HIR kicks in, (over 5100 RPM stock) the injectors are firing only once per rev, but the injectors are staying open longer to compensate.
Unfortunately, miscalculations are amplified by HIR, so it can get some really high spikes of rich/lean.
Porsche did about as good as they could with the stock maps.
There isn't a great deal more to get with the available 16x16 maps, the way they are arranged.
03-14-2013, 09:26 PM
#69
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03-14-2013, 11:28 PM
#70
Nordschleife Master
Sounds like you should (also) buy some of the plastic design III 30lb injectors?
Last edited by Hilton; 03-15-2013 at 01:20 AM. Reason: remove ebay link and part numbers to non-24lb injectors to avoid confusion
03-14-2013, 11:35 PM
#71
Drifting
Sounds like you should (also) buy some of these
http://www.ebay.com/itm/32LB-hr-336-...2424dc&vxp=mtr
They're Bosch 0 280 155 759 32lb 4-hole design III with the correct grooves for stock injector retainers.
03-14-2013, 11:52 PM
#72
Inventor
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Thread Starter
03-15-2013, 12:00 AM
#74
Inventor
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Thread Starter
Fit, yes.
I probably wouldn't go that big unless you put some decent cams in, and are SharkTuning.
24 lb is borderline for stock w/X-pipe, but it's close enough that I'm not swayed to move to 30's, yet.
It's more and more difficult to keep HCs reasonable at low (test range) rpms, the bigger you go.
Or maybe better said, the bigger I go.
I pretty much reverse the MAF scaling so there is little resolution down low, in order to have many more rows at max output (~320 rwhp max only).
I probably wouldn't go that big unless you put some decent cams in, and are SharkTuning.
24 lb is borderline for stock w/X-pipe, but it's close enough that I'm not swayed to move to 30's, yet.
It's more and more difficult to keep HCs reasonable at low (test range) rpms, the bigger you go.
Or maybe better said, the bigger I go.
I pretty much reverse the MAF scaling so there is little resolution down low, in order to have many more rows at max output (~320 rwhp max only).