I have 400cc injectors in place ATM but it's quite hard to get them to behave. I think I need 330cc-350cc injectors instead.
At idle I can get them to just about steady @ 14.7 AFR but when revved they go too lean, once holding at 3000 rpm I increase the duty to 20% more across the board and it fuels correctly. I assume that they are too big, I think I was told some time ago they where too big.
BTW - this is for the C1J
Does this sound right?
Last edited by TNT ANDY; 16-03-2011 at 23:49. Reason: More info added
Andy, I've been doing a fair bit of research into this subject recently, although i think Scoff would be your man to get the best advice.Originally Posted by TNT ANDY
I have 400cc injectors in place ATM but it's quite hard to get them to behave. I think I need 330cc-350cc injectors instead.
At idle I can get them to just about steady @ 14.7 AFR but when revved they go too lean, once holding at 3000 rpm I increase the duty to 20% more across the board and it fuels correctly. I assume that they are too big, I think I was told some time ago they where too big.
BTW - this is for the C1J
Does this sound right?
What fuel pressure rating are the injectors and what fuel pressure have you set?
Fuel flow(cc) = (MaxHP requeired x 5.6) / No Cylinders
for you = 250 x 5.6 / 4 = 350cc injectors assuming 100% duty (TF).
Guessing you want to be at 80% max duty.
Static flow = (TF x 100) / (n X m)
SF = 350 X 100 / 1 X 80 = 437 cc injectors.
Given the above (and my limited knowledge) I recon your about there if you want to be sorted for 250bhp at a later date, you would want to be around 350cc for max 200HP @ 80%.
I think there is another issue causing the problem, perhaps too much fuel pressure? Your sizes sound about right.
Cheers alistair, that sounds about right, and I've had some good advise from the afore mentioned Scoff. 400cc is a little too big. (got these some time ago on someone elses say-so, I'm learning here, best do some research yourself first)
I had a look @ http://www.megamanual.com/v22manual/minj.htm#size which gave me a good indication..
Going back to your first point, I'm running 3 bar @ idle on the fuel rail and I wasn't aware there was a pressure rating for injectors.
Just to add to my final hurdles my breaks have just packed up peddle goes to the floor, no leaks - grrrrrr - master cylinder. I just want to get her back on the rd - 3.5 years off the road.
Wooooosaaaaaaahhhhhhhh
Wooooosaaaaaaahhhhhhhh
(ref - bad boys)
Andy, no, what you describe in your first thread just a mapping issue. IE, it isn't mapped yet, is it ? The map I sent you is from another engine I did so it will fuel differently at different RPMs. As long as you can get it to idle stable then the chances are your injectors will be fine once you have a fuel map for you're engine.
Sorted Scoff - I'll leave alone. - I've got a stable idle.
I'll be in contact soon.
On what rpm / AFR were you able to get a stable idle? What PW do you have?
I'm running MS2 with 350ccm injectors @3 bar. But around 900rpm it doesn't idle fine. It's a bit rough.
I've tried also E85 which was better @idle, but the injectors were not enough on boost.
Also what advance do you use @ idle?
Last summer I did my flexifuel conversion for the C1J. Im still running my 360cc injectors since I didn't have time to figure out new size and run only on 0,6bar. Now Im thinking of rising the boost pressure back to 1,3-1,4 bar which it was before I broke my t25 some time ago.
If I'm running E85 fuel I should use 470CC injectors since I need about 30% more, but will they be too big for running std petrol? Idle has always been little rough even with 360cc injectors and petrol.
Any opinions? Has anyone run injectors over 400CC on C1J?
It is not just injector size that is important, but the quality of injector, it's spray pattern and angle. Some injectors will work better than others in different manifolds or cylinder heads.
Generally speaking, modern injectors are a lot better at small pulse widths than old bosch EV1, etc. For example, I can have my modern 2000cc bosch injectors idling at 1000rpm with A/F in the high 13s'. OK, they struggle a little bit but it shows what is possible.
So choose a modern injector, only as big as it needs to be, and no more fuel pressure than is neccessary and you should be fine.
Smaller injectors with a rising rate regulator might also be an option as long as your fuel system can deal with the pressure OK.
Good points, as usual, thanks. I'll have to see what I can find at sensible costs. I can always go to MOT with my old 360cc injectors if idle becomes problematic.
Bosch Green Giant injectors (0280 155 968) are very well liked as they have a good spray pattern. They are a good upgrade for a number of vehicles/engines and are around 450cc/min @ 3 Bar pressure.
I found this shop which has quite good list of choices available. Now I'm thinking should I choose the bosch green one which would go 440cc or 525cc EV14 ones.
http://www.injectorsonline.com/indiv...cid=74&scid=11
I suppose those green giants would work as most of the time Im not running full 85% ethanol anyway. Are they "modern spray pattern injectors" which Scoff talked about?
are the Bosch Green Giant injectors the same like they use on the ford cosworth upgrade ones?
Not sure about that, but here's the cheapest place I've found for them.
http://www.turnermotorsport.com/p-20...0-155-968.aspx
http://www.ebay.co.uk/itm/Genuine-Bo...item416041402b
Good old hellbay found them bit cheaper.
Also, since there are quite many efi c1j engines in the club, it would be interestig to hear what injectors others are using?
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