Can CIS be modified to be non-linear?
05-17-2005, 09:53 AM
#1
Burning Brakes
Thread Starter
Can CIS be modified to be non-linear?
Guys
Well ive been thinking.... (please correct me if im wrong here...) I know our CIS system is a bit basic now and EFI is the way to go but our main problem with CIS is its just linear to the rpm and that means for us with a few mods running it rich at idle. I understand simply converting to EFI means you can run it un-rich at idle and an over rich engine automatically looses power anyway so you can unleash some extra power without modifing anything.
So apart from going the whole hog with EFI why cant we make something that justs increases the fuel ontop of the normal linear fuel increase (extra injector, mod the fuel head, enrichment etc etc)- surely this will make it more into a curve and it could be adjustable as well, then set it up on a rolling road by looking at the A/F ratio etc- i know it wont be the same as EFI but i would be alot better? and itll mean running it unrich at idle.... etc etc
Well ive been thinking.... (please correct me if im wrong here...) I know our CIS system is a bit basic now and EFI is the way to go but our main problem with CIS is its just linear to the rpm and that means for us with a few mods running it rich at idle. I understand simply converting to EFI means you can run it un-rich at idle and an over rich engine automatically looses power anyway so you can unleash some extra power without modifing anything.
So apart from going the whole hog with EFI why cant we make something that justs increases the fuel ontop of the normal linear fuel increase (extra injector, mod the fuel head, enrichment etc etc)- surely this will make it more into a curve and it could be adjustable as well, then set it up on a rolling road by looking at the A/F ratio etc- i know it wont be the same as EFI but i would be alot better? and itll mean running it unrich at idle.... etc etc
05-18-2005, 10:54 AM
#2
Burning Brakes
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Brent, moderator at www.turbo911.com has tested more or less every combination there is on CIS for his 930 (which is a bit different from our cars). Getting more than 500 hp with CIS.
If I remember correctly he got the best effect when he used a switch that got triggered at a specific rpm, he then lowered the control pressure in the WUR (AFR gets richer). This was in combination with a "flowed" distributor, a HF turbo and some other mods. The problem he had was that in order to get it rich enough at full boost it got too rich a lower rpm's.
But Miles, are you sure you have a problem, does your AFR realy lean out on full boost ?
I logged my AFR on my car, running 0.7, 0.8, 0.9 and 1.0 bar, with a little bit of tuning my AFR is just where I want it. Not sure the ROW 964 turbo has the same problem as the US 930.
If I remember correctly he got the best effect when he used a switch that got triggered at a specific rpm, he then lowered the control pressure in the WUR (AFR gets richer). This was in combination with a "flowed" distributor, a HF turbo and some other mods. The problem he had was that in order to get it rich enough at full boost it got too rich a lower rpm's.
But Miles, are you sure you have a problem, does your AFR realy lean out on full boost ?
I logged my AFR on my car, running 0.7, 0.8, 0.9 and 1.0 bar, with a little bit of tuning my AFR is just where I want it. Not sure the ROW 964 turbo has the same problem as the US 930.
05-18-2005, 10:59 AM
#3
Burning Brakes
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I should add that Brent concluded you don't need the Andial nor the Rice enrichment kits, you can get the same effect yourself with a little bit of work (adjustable control pressure basically).
05-18-2005, 01:36 PM
#4
Burning Brakes
Thread Starter
thanks Staffan, i think i am not running lean but I am having a dyno done on firday to make sure all is ok. my mechanic leaned it out for the mot but i need to know whats really going on - we didnt even get a reading before the CAT to see what the co2 is.
I really interested in the fact of making CIS more effcient. thanks for the Brent info- i know him from 911turbo... i remember hes a Don with the enrichment stuff so i will also contact him.
The WUR thing is interesting too- just what i need... the main thing it can increase the fuel so even though the idle will be rich - it should still be less vs without it. what would be good if it can measure the fuel ratio and then automatically adjust- but the rpm thing is still a much better step!
I really interested in the fact of making CIS more effcient. thanks for the Brent info- i know him from 911turbo... i remember hes a Don with the enrichment stuff so i will also contact him.
The WUR thing is interesting too- just what i need... the main thing it can increase the fuel so even though the idle will be rich - it should still be less vs without it. what would be good if it can measure the fuel ratio and then automatically adjust- but the rpm thing is still a much better step!