problem with new injectors
Thread Starter
Cruising
Joined: Aug 2005
Posts: 10
Likes: 0
From: Wadsworth OH
problem with new injectors
I installed 26lb. injectors and an adjustable fuel pressure regulator. No mods to the engine, just k&n with flowmaster exhaust and went back to OEM thermostat. When at partial throttle the car runs fine. The problem arises when over 80 percent throttle is applied, the car bogs down and occasional black smoke. I have only put 60 miles on the new set up. The pressure is set at 40 and a cap, rotor, plugs and plug wires installed. I called Summit Racing where I purchased the injectors and there response was the computer had to adjust to the different injectors is this true or did they lead me astray? Any input would be greatly appreciated especially before I leave for Carlisle. 
Thread Starter
Cruising
Joined: Aug 2005
Posts: 10
Likes: 0
From: Wadsworth OH
Which is stock size I have been told 22# and 24#. This becoming frustrating. Summit Racing said stock was 24# and suggested me to go with the 26# for more performance. Do need to get one burned or can I buy an aftermarket chip? Any input is greatly appreciated!
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
Originally Posted by Morley
In 1985 stock size was 24# BUT! they ran them at 36 psi. From 1986-1991 the stock size was 22# at 43 psi.
Now this, to me, is where things get confusing, and I believe it is to others. And that is how injectors are rated and at what pressure?Example, when I read my orig. chip in CATS it shows 23.8 lb injectors so you would think that a 24 would be fine to do a replacement with. Wrong.
Here is the problem. Those GM factory injectors are rated at a pressure around 43.5 lbs I believe.
Most aftermarket injectors such as the SVO injectors flow their 24lbs at a lower pressure, somewhere around 38-39 lbs I believe.
So in this example when installing the SVO 24lb injectors in a stock corvette they actually flow more then 24lbs. With a stock fuel pressure regulator it is around 26.5 lbs.
And to add even more confusion to this, as Morley pointed out, not all vettes have the same pressure settings.
Pro
Joined: Sep 2001
Posts: 542
Likes: 1
From: Stuck in the 80's
Originally Posted by 93 ragtop
Now this, to me, is where things get confusing, and I believe it is to others. And that is how injectors are rated and at what pressure?Example, when I read my orig. chip in CATS it shows 23.8 lb injectors so you would think that a 24 would be fine to do a replacement with. Wrong.
Here is the problem. Those GM factory injectors are rated at a pressure around 43.5 lbs I believe.
Most aftermarket injectors such as the SVO injectors flow their 24lbs at a lower pressure, somewhere around 38-39 lbs I believe.
So in this example when installing the SVO 24lb injectors in a stock corvette they actually flow more then 24lbs. With a stock fuel pressure regulator it is around 26.5 lbs.
And to add even more confusion to this, as Morley pointed out, not all vettes have the same pressure settings.
Here is the problem. Those GM factory injectors are rated at a pressure around 43.5 lbs I believe.
Most aftermarket injectors such as the SVO injectors flow their 24lbs at a lower pressure, somewhere around 38-39 lbs I believe.
So in this example when installing the SVO 24lb injectors in a stock corvette they actually flow more then 24lbs. With a stock fuel pressure regulator it is around 26.5 lbs.
And to add even more confusion to this, as Morley pointed out, not all vettes have the same pressure settings.
And that is why injector ratings alone do not tell the whole story, you must know @ what fuel pressure. Since you have adjustable regulator, you may be able to turn it down a little more, but a chip with the correct value is better. A scan of your BLM's and a tweak of the fuel map is best.
Drifting
Joined: May 2003
Posts: 1,730
Likes: 1
From: Charlotte NC
St. Jude Donor '05
IF any of you guys do subjective before and after injector swap programmings you'll find alot of unusual and strange things.
Theres alot more to programming injectors than just putting in a constant.. Thats why I always like to see people go with nice consistant and repeatable injectors like SVO's.
Theres alot more to programming injectors than just putting in a constant.. Thats why I always like to see people go with nice consistant and repeatable injectors like SVO's.
Team Owner
Joined: Sep 2002
Posts: 22,209
Likes: 12
From: OBAMA IS HITLER
I've got the 24# Ford SVO's (translates to a little over 26.0# @ 43.5psi, as 93ragtop noted) in my setup.
Alvin did my chip, and the power is smooth and straightlined (sotp) right up thru the RPM range
Alvin did my chip, and the power is smooth and straightlined (sotp) right up thru the RPM range
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