Do I Need Larger Injector Size?
Thread Starter
Racer
Joined: Aug 2006
Posts: 355
Likes: 0
From: Sahuarita AZ
Do I Need Larger Injector Size?
Hi,
I have a 1998 mn6 with the stock injectors. The car has a mild cam, headers and 90/90 setup with many bolt ons ( 390rwhp ). I just installed AFR 205 heads 59cc. Need to get a new power tune but unsure about increasing injector size? Any thoughts?
thanks
I have a 1998 mn6 with the stock injectors. The car has a mild cam, headers and 90/90 setup with many bolt ons ( 390rwhp ). I just installed AFR 205 heads 59cc. Need to get a new power tune but unsure about increasing injector size? Any thoughts?
thanks
Team Owner
Joined: May 2001
Posts: 36,836
Likes: 244
From: Dear Karma, I have a list of people you missed.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16
I'm saying yes. Your stockers are probably operating near the upper limit of their duty cycle as is.
Pro
Joined: Aug 2007
Posts: 544
Likes: 0
From: Oxnard Ca
I am actually curious about this as well. I am doing similar upgrades as you chevybob but I will also be adding a 100 shot nitrous. I was looking at some used 42lb in the parts forum, would those be too big?
Melting Slicks
Joined: Feb 2001
Posts: 2,804
Likes: 358
From: Northville, MI
Find a friend with a full feature scanner and run a 15-20 minute log to find duty cycle and performance characteristics of your car. From the scan they or a tuner can either recommend keep the current injectors or get larger and what size you need. Also, this is the info the tuner would need to give you the intermediate values in your final tune. By the way in that 15-20 minute scan you will have to sacrifice some gas in doing some all out runs thru the gears.
Drifting
Joined: Dec 2005
Posts: 1,720
Likes: 3
From: East Hampton CT
before you go spending money, see what your tuner says. Stock injectors are usually good for ~400rwhp...and SVO 30's for at least 450-500rwhp. Some people go too big (I went to #42) and then have trouble tuning.
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Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
I have a 98 with 390 RWHP and on the data logger the duty cycles will shoot up to around 88% they say 80% is about the limit--or they will overheat-98's came stock with 28 lb. injectors--If I were racing a lot or running at WOT alot I should change them to at least 30 lbs. However for intermitant short use they should be fine and I haven't had any issues
PS I would make sure you have adequate fuel pressure and flow--AND make sure your voltage is consistant at the fuel pump--
PS I would make sure you have adequate fuel pressure and flow--AND make sure your voltage is consistant at the fuel pump--
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
Only if you will be using a DRY nitrous system the injectors will need to be addrerssed--On a WET system additional fuel is added in the nitrous nozzle and mixed with the NOS
Drifting
Joined: Dec 2005
Posts: 1,720
Likes: 3
From: East Hampton CT
Lots of reputable tuners have run injectors at 130% duty cycle with a solid AFR and no injector issues.
Duty cycle is just the computers estimate....based on other parameters. Just because the computer "thinks" your injectors are maxxed out, doesn't mean they are. If your AFR is solid, you're good to go.
Duty cycle is just the computers estimate....based on other parameters. Just because the computer "thinks" your injectors are maxxed out, doesn't mean they are. If your AFR is solid, you're good to go.
