Injector upgrade needed with bigger cam?
Thread Starter
Racer
Joined: Sep 2004
Posts: 400
Likes: 4
From: Phoenix AZ
Injector upgrade needed with bigger cam?
I have pulled the trigger on a new cam for my 02 Z. I am now gathering the other parts for the job and the question of upgrading to larger injectors has surfaced. I am hoping to be around 400-420 rwhp when all said and done. Again just cam and full exhaust at this point, no heads or intake. With that said am I still within the stock Z06 injectors limits? In my last search I read perhaps that 450 rwhp was the limit of stock injectors. Comments appreciated.
Safety Car
Joined: Oct 2007
Posts: 3,903
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From: You know your drunk when you swerve to miss the tree then you realize its your air freshener! Covington Ga
Cant remember the number, but I have LT's no cats, CAI, stock intake manifold, and 241 heads with dual springs, hardened push rods. I know I was no where near 100%. They told me I could still do heads and intake manifold and be fine with the stock ones.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
With just headers, ported TB and a VARARAM and a tune, my 02 ZO6 was making 390 RWHP 375 RWTQ, injector duty cycle was in the 100-103% in the upper RPM band at WOT.
I went with 42's for my heads / cam / ported fast 90 / ported 90mm TB VARARAM and my duty cycle are in the mid 40's. 36's would have worked perfect. Now I'm making 450 RWHP
Unless you have a big cam and ported manifold to help it get more air, 36's would be what you need.
I went with 42's for my heads / cam / ported fast 90 / ported 90mm TB VARARAM and my duty cycle are in the mid 40's. 36's would have worked perfect. Now I'm making 450 RWHP
Unless you have a big cam and ported manifold to help it get more air, 36's would be what you need.
Drifting
Joined: Jan 2008
Posts: 1,283
Likes: 13
From: Akron Ohio
Bill, you think COT could have been the reason for 103% duty cycle? My 02 has long tubes, CAI and exhaust and I was at 98% duty cycle. I disabled COT, need to look through my logs but I believe the duty cycle was down in the 70%'s. A friend of mine suggested this change in my tune, it seemed to be the key.
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Thread Starter
Racer
Joined: Sep 2004
Posts: 400
Likes: 4
From: Phoenix AZ
This is the part the confuses me and must be due to other car variables.
0331MARINE- gets reports of no where near max duty cycle with a few mods.
Bill Curlee- less mods and and yet over 100% of cycle.
So what are the variables to account for, COT, what about engine miles as I only have 15K?,
0331MARINE- gets reports of no where near max duty cycle with a few mods.
Bill Curlee- less mods and and yet over 100% of cycle.
So what are the variables to account for, COT, what about engine miles as I only have 15K?,
Last edited by 94brick; Jan 22, 2010 at 11:27 AM.
Racer
Joined: Aug 2008
Posts: 404
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From: NYC
I have an '02 (non-z06) and put some z06 heads and a G5X3 cam in along with some headers, a vararam, and underdrive pulley. my stock injectors were at 120% duty cycle at WOT. I have no numbers as the car was street tuned. IIRC your injectors should be around 80-85% duty cycle at WOT. that way you have alittle room to grow also. i put 38lb injectors in and the car flies! BTW compression is at 11.5:1
Racer
Joined: Jul 2007
Posts: 444
Likes: 4
From: Waynesboro VA
I have an '02 (non-z06) and put some z06 heads and a G5X3 cam in along with some headers, a vararam, and underdrive pulley. my stock injectors were at 120% duty cycle at WOT. I have no numbers as the car was street tuned. IIRC your injectors should be around 80-85% duty cycle at WOT. that way you have alittle room to grow also. i put 38lb injectors in and the car flies! BTW compression is at 11.5:1
Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Or street, or track. Wherever you can reach hp peak while logging IDC.
Assuming the car will get tuned after the cam swap, the tuner will be able to tell you right away if you need to upsize the injectors or not. The stock ones usually max out around 410-420rwhp.
If you do need more injector, the red top 30# SVO injectors will more than suffice, and will support over 450rwhp.
Assuming the car will get tuned after the cam swap, the tuner will be able to tell you right away if you need to upsize the injectors or not. The stock ones usually max out around 410-420rwhp.
If you do need more injector, the red top 30# SVO injectors will more than suffice, and will support over 450rwhp.
Le Mans Master
Joined: Nov 2003
Posts: 8,004
Likes: 250
From: Tampa Fl
St. Jude Donor '12-'13-'14
If your asking will your injectors still work, Yes they will still work with 420 RWHP. Cruising around time, you wont have much of an issue.
Will they work properly at WOT. No. At WOT you will clearly be over your usage rate for your 28.8 injectors.
Would you put in undersized springs for your new cam?
I had 28.8 injectors in when I was at 425 RWHP, and I was getting 110-112 usage rate at WOT. Your safe if your injectors run at 80-85% at WOT.
pick up some ford 30# injectors and keep your motor happy
It will be easy for your tuner to tell you what your duty cycle is when your car is getting tuned. But then when you see your under injectored and go out and buy new ones, your tuner may bang you a couple more bucks for a touch up tune and rescaling of yout injectors
Will they work properly at WOT. No. At WOT you will clearly be over your usage rate for your 28.8 injectors.
Would you put in undersized springs for your new cam?
I had 28.8 injectors in when I was at 425 RWHP, and I was getting 110-112 usage rate at WOT. Your safe if your injectors run at 80-85% at WOT.
pick up some ford 30# injectors and keep your motor happy
It will be easy for your tuner to tell you what your duty cycle is when your car is getting tuned. But then when you see your under injectored and go out and buy new ones, your tuner may bang you a couple more bucks for a touch up tune and rescaling of yout injectors
Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
An injector flow rating is always relative to fuel pressure.
Most injectors are flow-rated at 3bar (43.5 psi) fuel pressure. But C5 fuel system runs at 4bar (58psi).
So, given an injector rated to flow 30# @ 43psi...Used at 58psi, it is actually a 36# injector.
This is why those "little" 30s are good for so much more hp over the stock 28.8s. (which btw are rated 28.8# @58psi).
Racer
Joined: Feb 2005
Posts: 436
Likes: 1
From: Gatineau Quebec
Closer to 36#
An injector flow rating is always relative to fuel pressure.
Most injectors are flow-rated at 3bar (43.5 psi) fuel pressure. But C5 fuel system runs at 4bar (58psi).
So, given an injector rated to flow 30# @ 43psi...Used at 58psi, it is actually a 36# injector.
This is why those "little" 30s are good for so much more hp over the stock 28.8s. (which btw are rated 28.8# @58psi).
An injector flow rating is always relative to fuel pressure.
Most injectors are flow-rated at 3bar (43.5 psi) fuel pressure. But C5 fuel system runs at 4bar (58psi).
So, given an injector rated to flow 30# @ 43psi...Used at 58psi, it is actually a 36# injector.
This is why those "little" 30s are good for so much more hp over the stock 28.8s. (which btw are rated 28.8# @58psi).
Intermediate
Joined: Oct 2008
Posts: 43
Likes: 0
From: bremerton wa
33#injectors from C6 in 99' LS1 C5.
I am using C6 90mmTB, intake, and injectors..33#'s I believe... Anyone using these on their C5??? What kind of power will they support???
Is it worth it to have them sent out to have them flow matched, and if so who to send them to...? What does Mr. Curlee think about this combo? Going to use a Mayhem II cam, both TB and LS2 manifold are ported.
Thanks,
Marc
Is it worth it to have them sent out to have them flow matched, and if so who to send them to...? What does Mr. Curlee think about this combo? Going to use a Mayhem II cam, both TB and LS2 manifold are ported.
Thanks,
Marc