750cc primaries are not enough!
09-19-2002, 01:57 PM
#11
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Location: Bay Area, CA
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Originally Posted by j9fd3s' date='Sep 19 2002, 10:46 AM
you can move the "staging" bar over so the secondaries come on sooner.
mike
mike
09-19-2002, 04:13 PM
#12
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Join Date: Jan 2002
Posts: 77
I thought a lot of people were using 1300 secondaries. Or is that just for stock turbos. Well either way you got your car back, and once you get your primaries and secondaries and tuned you'll be running, well you'll be haulins some major ars.
- Steiner
- Steiner
09-19-2002, 07:24 PM
#15
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Location: Birmingham, AL
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I though I was right about changing the staging with the Haltech. I believe since your staging is probably based on 550/850 or soemthing like that it just needs to be tweaked for the new size difference in injectors.
The only thing with going from 750 to 850 is that if your already maxing out 750's adding another 100cc's prob isnt enough and if you go larger its supposed to be much harder to fine tune. From what I hear (I've never tried larger than 850pri) the larger injectors just dump to much fuel with each pulse and just cant be fine tuned like 850 and smaller. Well let me rephrase....it CAN be fine tuned its just much harder.
You have enough injector right now to make 550 at the wheels with stock fuel pressure. It sounds like more of a tuning issue than a fuel issue to me.
But you know how all this goes, I havent seen the car so who am I to say, I'm just throwing out my .02
STEPHEN
The only thing with going from 750 to 850 is that if your already maxing out 750's adding another 100cc's prob isnt enough and if you go larger its supposed to be much harder to fine tune. From what I hear (I've never tried larger than 850pri) the larger injectors just dump to much fuel with each pulse and just cant be fine tuned like 850 and smaller. Well let me rephrase....it CAN be fine tuned its just much harder.
You have enough injector right now to make 550 at the wheels with stock fuel pressure. It sounds like more of a tuning issue than a fuel issue to me.
But you know how all this goes, I havent seen the car so who am I to say, I'm just throwing out my .02
STEPHEN
09-19-2002, 07:53 PM
#16
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Originally Posted by Judge Ito' date='Sep 19 2002, 07:53 PM
I went with the 850cc primary, I didn't want to spend 3 hours fine tunning does 1300cc's I have. Hey Vosko just let me drive it one more dayyyyyyyyyyyyyyyyyy Man gob bless Felix Wankel...
09-19-2002, 08:09 PM
#17
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Join Date: Sep 2002
Posts: 2,550
Hmm.. are you still running the stock port a side, a bridge... you could always gut the inside of the upper intake manifold basicly making it a surge tank, then batch fire the injectors all at once at idol so there never is a transition.. This works good with a bridge port are large side port with some overlap.. Give me some more info on your set up and I'll try to help you out.. You should have enough fuel for a good 500+ hp right now..
09-19-2002, 11:51 PM
#19
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Join Date: Jul 2002
Posts: 7
I don't think big primaries are the way to go. I don't know about the Haltech, but ECUs I've dealt with make the transition from primaries only to primarys and secondarys when the primaries reach a certain duty cycle (say 80%). At this point the primary duty cycle is cut back and the secondaries come in. So I don't understand why your primaries were maxing out.
What I do know is that the ECU MUST know the ratio of the sizing between the primarys and secondaries or a lean or rich spot will be encoutered during the transition. If you've left the ratio set for 550/850 (ratio 0.647) and changed to 720/1600 (ratio 0.45) then you are bound to run into trouble unless you change the ratio used by the ECU.
Also big primaries mean that you have very little resolution for tuning around idle and cruising. So in my opinion keep small primarys (even 550s)
and go for however big (or many) injectors you need on the secondaries. But make sure you let the ECU know about the ratio change. I'd be surprised if the Haltech doesn't allow for this adjustment.
What I do know is that the ECU MUST know the ratio of the sizing between the primarys and secondaries or a lean or rich spot will be encoutered during the transition. If you've left the ratio set for 550/850 (ratio 0.647) and changed to 720/1600 (ratio 0.45) then you are bound to run into trouble unless you change the ratio used by the ECU.
Also big primaries mean that you have very little resolution for tuning around idle and cruising. So in my opinion keep small primarys (even 550s)
and go for however big (or many) injectors you need on the secondaries. But make sure you let the ECU know about the ratio change. I'd be surprised if the Haltech doesn't allow for this adjustment.
09-20-2002, 02:28 AM
#20
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Posts: 2,550
Injector change over occures at 40%, what is hard to control is the transition between them. Where the problem comes in is that 40% on a 550cc inj. is way diffrent that 40% on a 720cc inj. This makes the injector change over happen in a completly diffrent part of the map where the engine is under more power. The problem with this is that when the injector change over occures fuel starts comming in from the secondary port and the fuel on the primary side is cut in half. This interuption usually causes a slight lean condition for a split second and this can kill a engine under power. What you have to do tune in a small overlap between when the secondary injector starts to fire and when the primary cuts it's fuel in half and play around with the the speed that the injectors transition. The bigger the injector and injector diffrence the more time you need.. You can also play with when the injector change over occures Ie. make it happen at 20%, but this requires a lot of adjustments to the fuel map.. The Power FC with the Datalogit allows you to adjust these setting.. I'm not sure about the Haltec..