85 ONLY corvette's "special" injector size?
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1st Gear
Joined: Sep 2004
Posts: 1
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85 ONLY corvette's "special" injector size?
I had found a few resources that state that the 85 corvette ran a lower fuel pressure than any other TPI application. I seem to remember that it might have also had a different injector size. I know this is a strange request but I cant seem to find a single one of these resources now.
Does anyone else know of this 85 vette only oddity? I seem to remember it being an odd size for a 350, like 19 or 26 pounds or something like that. something other than the regular 22 pound size?
Does anyone else know of this 85 vette only oddity? I seem to remember it being an odd size for a 350, like 19 or 26 pounds or something like that. something other than the regular 22 pound size?
Pro
Joined: Mar 1999
Posts: 678
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From: Oslo, Norway
Hi. I toot have an 85 and as I know it is 24lbs injectors. To turn the fuel pressure up to 50 psi is after my meaning far too much for a stock 85. The power given in the motor is not linear to the fuel pressure. You can even have a drop in the power by increasing too much on the stock 85.
The heads do not manage to get a proper air fuel mixture at full throttle.
In the controlling range of the computer it will most probably work.
Then cast iron heads and the tpi will not manage flow enough air for that kind of fuel volume. If you have changed the cam to a more progressive one, changed the TPI to an aftermarket giving more air, changed the exhaust etc you should increase the pressure for not going too lean at wot. At the upper part of the throttle area(3/4 and up) the ECM sets the duty cycle on the injectors only after the TPS voltage so with a pressure that is different from that giving a certain air/fuel ratio you may have trouble.
There is another problem with a 50psi pressure that is the idle. The vacuum on the fuel pressure regulator ensures that the pressure decreases at idle and the idle is calculated with a certain amount of fuel at a certain amount of counts from the AIC to give a certain duty cycle on the injectors. With a high pressure I am not sure that the injectors/ECM manage that. So you have to adjust the idle and it may give you some odd reactions on the idle rpms. At least you may have to make the minimum idle air adjustment again.
It would be interesting with comments from others also!
The heads do not manage to get a proper air fuel mixture at full throttle.
In the controlling range of the computer it will most probably work.
Then cast iron heads and the tpi will not manage flow enough air for that kind of fuel volume. If you have changed the cam to a more progressive one, changed the TPI to an aftermarket giving more air, changed the exhaust etc you should increase the pressure for not going too lean at wot. At the upper part of the throttle area(3/4 and up) the ECM sets the duty cycle on the injectors only after the TPS voltage so with a pressure that is different from that giving a certain air/fuel ratio you may have trouble.
There is another problem with a 50psi pressure that is the idle. The vacuum on the fuel pressure regulator ensures that the pressure decreases at idle and the idle is calculated with a certain amount of fuel at a certain amount of counts from the AIC to give a certain duty cycle on the injectors. With a high pressure I am not sure that the injectors/ECM manage that. So you have to adjust the idle and it may give you some odd reactions on the idle rpms. At least you may have to make the minimum idle air adjustment again.
It would be interesting with comments from others also!
