Grand Prix Injectors

Bad35thSC

Registered User
Does anybody know if fuel injectors from a 01 Grand Prix GTP will fit in my 90 SC, my buddy is selling his 42# injectors and I wanna know if they'll fit in my car. Thanks
 
As long as the sensor plugs are the same, they should fit, but check the o-rings. I'm pretty sure they have to be ford injectors only...
 
42s are almost pointless if you think about it, depends on your goals though but... using decipha injector equation

30 * 1.6 * 6 * .8 = 230rwhp
36 * 1.6 * 6 * .8 = 276rwhp
42 * 1.6 * 6 * .8 = 322rwhp
60 * 1.6 * 6 * .8 = 460rwhp
80 * 1.6 * 6 * .8 = 614rwhp
120 * 1.6 * 6 * .8 = 921rwhp
160 * 1.6 * 6 * .8 = 1228rwhp
 
I assume that he put those 42lb injectors in the Grand prix at some point since they come with Bosch giant white 36lb injectors from factory. Grand prix use a high impedance injector with EV1 connector just like a SC and should work fine. I used to use 8 of the grand prix injectors in my mustang,but like decipha said...It depends on your goals.
 
No they will not work. The plug in is not the same.

Incorrect.

All 1997-2003 Grand Prix GTP and 1997-2000 Grand Prix GT use EV1 connectors, same as the SC.

All 2001+ Grand prix GT, and 2004+ Grand Prix GTP use EV6 connectors, and are not compatible.

I am running the old 42lb injectors i had in my SC in my 2000 GTP as we speak. The GTP's 53psi base fuel pressure gets a little more headroom out of the 42's than the SC does. And the GTP doesn't spin the blower as hard, even with smaller pulleys.. Works great!
 
42s are almost pointless if you think about it, depends on your goals though but... using decipha injector equation

30 * 1.6 * 6 * .8 = 230rwhp
36 * 1.6 * 6 * .8 = 276rwhp
42 * 1.6 * 6 * .8 = 322rwhp
60 * 1.6 * 6 * .8 = 460rwhp
80 * 1.6 * 6 * .8 = 614rwhp
120 * 1.6 * 6 * .8 = 921rwhp
160 * 1.6 * 6 * .8 = 1228rwhp

Can you explain this math please?
 
this is my own equation that i've developed myself

deciphas injector equation is broken down by

inj size x 1.6 (lbs to power) x num of cylinders (ie injectors) x (.8 extra fuel for boost-omit if not boosted) = rwhp

for example

30 * 1.6 * 8 = 384rwhp, 30lb injectors on a v8 with no boost is good up to 384rwhp

clear as mudd?
 
Yep sure is clear as mudd. The 331in my 95 cobra put down 320rwhp on a land and sea dyno. This is a load bearing dyno like a Mustang dyno. On a dynojet that would be about 350rwhp. Before the engine was together I did the math and the stock 24lb injectors would have been rright on the 80% limit. I had that math checked by my cam grinder who also said I could use 24's. I have not paid attention to duty cycle on any dyno results or data logging I have done because the injector was sized appropriately so I can not verify exactly what it is. I just have a hard time fathoming Ford would put a relatively large injector on this engine and leave so little wiggle room. It is not characteristic of them. A 5.0 Mustang can safely run a 19lb injector up to about 300fwhp a full 75hp over stock. Yet you are telling me a SC will run out of injector at 230rwhp, only 40 to 50hp over stock? I don't like your math. Hell even with your math a v8 should be putting out 154 more HP than a supercharged v6 just because it has 2 more cylinders! At the rpm the SC supercharged 3.8 makes peak power I find it hard to believe a mild bolt on car will be maxing out the factory injectors.
 
Yep sure is clear as mudd. The 331in my 95 cobra put down 320rwhp on a land and sea dyno. This is a load bearing dyno like a Mustang dyno. On a dynojet that would be about 350rwhp. Before the engine was together I did the math and the stock 24lb injectors would have been rright on the 80% limit. I had that math checked by my cam grinder who also said I could use 24's. I have not paid attention to duty cycle on any dyno results or data logging I have done because the injector was sized appropriately so I can not verify exactly what it is. I just have a hard time fathoming Ford would put a relatively large injector on this engine and leave so little wiggle room. It is not characteristic of them. A 5.0 Mustang can safely run a 19lb injector up to about 300fwhp a full 75hp over stock. Yet you are telling me a SC will run out of injector at 230rwhp, only 40 to 50hp over stock? I don't like your math. Hell even with your math a v8 should be putting out 154 more HP than a supercharged v6 just because it has 2 more cylinders! At the rpm the SC supercharged 3.8 makes peak power I find it hard to believe a mild bolt on car will be maxing out the factory injectors.

I know from experience that I was above 80% duty cycle with 42 lb/hr injectors on a bolt-on only SC engine that made 308 rwhp. As the ability to datalog these cars has become easier, it is becoming evident that what used to be considered a safe injector is not always the case. Heck, when Ford bumped the hp from 215 to 230 crank hp in 1994, they bumped the injectors from 30 lb/hr to 36 lb/hr, meaning apparently there wasn't any room on the 30 lb/hr injectors for the additional 15 crank hp; so I'm not sure how much additional capacity there really is on factory injectors.
 
There is no room on the older cars with the 30's to grow. 42's are at the edge at 300rwhp, especially in an auto... running 42's at 330rwhp is running on the bad side of maxing the injectors out. Injectors behave in a funny way once they get to about 90%-95% duty cycle, but I am not going to get into the details here.

Now if you ramp up the fuel pressure to 42 psi static instead of the factory 39psi, you might get to what decipha is calculating out... but running an AFPR these days is not needed like it used to be.

There is way too many variables to consider to think a one fit formula is going to fit all engines. Our motors have a very lousy efficiency level and generally require more fuel to make a certain amount of horsepower than other motors out there.... so again, we typically have to throw out what is considered the "norm" for v8's and go by the experience that has been gained over the years on these specific motors.

I typically recommend upgrading injectors once you see 85% or more duty cycle. Even better and easier.... just get a set of 60# injectors, get a chip, and call it a day, even if you are not aiming for 400rwhp. In a lot of cases, the new 60's have better flow control than the 42's have at short pulse widths.

Fraser
 
Yep sure is clear as mudd. The 331in my 95 cobra put down 320rwhp on a land and sea dyno. This is a load bearing dyno like a Mustang dyno. On a dynojet that would be about 350rwhp. Before the engine was together I did the math and the stock 24lb injectors would have been rright on the 80% limit. I had that math checked by my cam grinder who also said I could use 24's. I have not paid attention to duty cycle on any dyno results or data logging I have done because the injector was sized appropriately so I can not verify exactly what it is. I just have a hard time fathoming Ford would put a relatively large injector on this engine and leave so little wiggle room. It is not characteristic of them. A 5.0 Mustang can safely run a 19lb injector up to about 300fwhp a full 75hp over stock. Yet you are telling me a SC will run out of injector at 230rwhp, only 40 to 50hp over stock? I don't like your math. Hell even with your math a v8 should be putting out 154 more HP than a supercharged v6 just because it has 2 more cylinders! At the rpm the SC supercharged 3.8 makes peak power I find it hard to believe a mild bolt on car will be maxing out the factory injectors.

Your Mustang had 8 x 24 lbs injectors. That's 192 total pounds per hour of fuel. The SC has 6 * 30 lbs injectors. That's 180 total pounds per hour of fuel.

So already, the Cobra has 6.7% more fuel available to make power.

Now, bear in mind that the Thunderbird uses a supercharger that takes a lot of power to operate at high boost. Maybe 75 horsepower?

So take your estimated 350 rwhp. Divide by 1.067 and get 328. Subtract 75 and you get 253.

Factor in differences in the engine, and possibly drivetrain loss, and they aren't too far apart.
 
Even more muddy math. Bottom line is it takes x amount of airflow to make Y amount of power. The air doesn't know if it is going into a supercharged v6 or a N/A v8. The only difference would be the BSFC number will be different. This will slightly decrease the total power that can be made. By dechipa math a SC motor can only make 38.33hp per cylinder but a v8 can make 48.125 on the same injector. At the same 48.125 per cylinder the v6 should be able to make 288.75. The higher BSFC number on the blower motor shouldn't equate to a 50+hp loss for the motor. To me it sounds like other factors limiting to power production.
 
Kurt can you explain to me what bolt ons are needed to reach 308RWHP? It may better help me understand this.

Actually, I confused myself. I've had so many iterations of my engine, I forgot where I was at with 42lb/hr injectors and 308 rwhp. I still don't really, but the more I think about it, I believe this was the first engine I built after I blew both headgaskets on the interanlly stock engine. Anyway, this was with Coy Miller heads, cam, pistons, etc....all the goodies, including a Pro-M 77mm maf calibrated to 42 lb/hr injectors. At the time, I think that MAF had a better calibration than anyone else I had heard about. When I got the car tuned, the tuner was only able to gain 8 rwhp over my factory tune.

Regardless, the 42 lb/hr injectors were barely able to keep up with the combo that only produced low-300's rwhp.

Sorry for the confusion.
 
Yes Kurt I don't consider a HCI car a bolt on car. It is still good info to have though as if I ever pop a gasket I will have a hard time not taking the magic die grinder to a few parts. And knowing if I get that far I will need more injector is good. Really don't want to go nuts with the tbird though as it will be my daily driver. The Mustang is my "race car". Thia is why under standing why a 30lb injector is barely adaquate is important to me.
 
Unless the 42s are cheap go straight to 60.

I'm on the edge of mine right now. Well any more mods and 60s will be a must. But for me Valve train/heads is next, so by the time add heads and cam I will be beyond the 42s. I'm not going to OD the blower until have better flowing heads, since don't see the point of raising temps if anit got too.
 
they got offered to me for $150, and i didn't know if they fit, which i just learned that they will. I am planning on building my motor this winter and I'm aiming for about 350-375 hp, so just waiting and getting 60's would obviously be a better idea
 
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