Mild built 351 EFI

[rjrobin2002]

I have searched and found about 50/50% people using 19lb versus 24lb injectors on mild built 351's. I was wanting to use Explorer upper/lower and TB. Would 19lb's be a major limit on my possible performance versus 24's with a custom computer tune/chip? Is there not a OEM maf computer already set up for 24lb injectors?

 

[ScottC]

I'm gonna go out on a limb and say 19s are fine for stock intake and TB. My daily driver '96 and the '96 engine I just picked up both have 19's.

For my '77 351 build, I'm using a Lightning GT40 and aftermarket heads and cam, so I've been encouraged by a few people to go up a size on the injectors. I have a set of 19s on a 351 lower manifold if you want them. I'm keeping the rails though.

 

[Viperwolf1]

I have searched and found about 50/50% people using 19lb versus 24lb injectors on mild built 351's. I was wanting to use Explorer upper/lower and TB. Would 19lb's be a major limit on my possible performance versus 24's with a custom computer tune/chip? Is there not a OEM maf computer already set up for 24lb injectors?

Some of the mustang cobras used 24 lb injectors. Good luck finding one. You'd be better off putting what you want on it then tuning it.

 

[HoosierDaddy]

I was wanting to use Explorer upper/lower and TB. QUOTE]

The Explorer lower will not fit a 351 , but the Explorer upper will fit a 351 GT40/ Lightning lower.
Make sense ?

 

[Broncobowsher]

The Explorer lower will NOT fit the 351.

The '93 Cobra had factory 24s on a 5.0
Ford Motorsports had a kit for a long time (probably gone now) that was the MAF, ECM and injectors as a package. Now most people will get a good MAF (not a tuned one as that will be a waste once...) you get a custom chip that will tune the engine to the MAF and injectors and get the timing right as well. Also use it to set idle speed, turn off thermactor and/or EGR and many other tuning aspects that can be dialed in much better then a pre-packaged box.

My 3.25" 330" stroked 5.0 with an explorer intake took 24's. If you have some good heads and turn a fair bit of RPM the 351 could use them as well.

OK, I will look up published numbers for recomended limits on injector sizes...
Published numbers for 19Lb injectors show they are good for about 275 HP (flywheel) on a naturally asperated V8, 24s are good for 345. Just about any good running 351 should be making 300.

Also for fuel pumps a 110Lph is safe for 310 HP and 155 Lph is good for 440 HP.

 

[RedEyedMex619]

i just picked up a maf and a set of 24lb on e-bay for 120. That are going in my 351w, im getting one part at a time.
My 2 cents on this is i read some where that the 460 efi have 24lbs, i was going to keep an eye at the boneyard for some. I know the SC T-bird came with 24 lbs. I don't know if you can use the maf from a sc t-bird. I think you need the 93 cobra ECU. that is where my researcher has taken me..
Has any one ran the typhoon efi intake on there 351w?
what size t-body do you suggest for a 351w, will the 65mm explorer be fine?
I'm trying to build an efi system for a 320-350 hp 351w

 

[bronco117]

My 351 is mild built, about 9.5:1 and RHS heads, stock lower to 5.0 upper. I tried a stock A9L ecc with an 80mm MAF and 24 lb injectors off of a 460. It ran but not very well. I downgraded to a 65MM MAF and the new style 19 lb injectors and it runs great. If I ever get around to reprogramming the ECC I might try the 24lb injectors again.

 

[Broncobowsher]

My 351 is mild built, about 9.5:1 and RHS heads, stock lower to 5.0 upper. I tried a stock A9L ecc with an 80mm MAF and 24 lb injectors off of a 460. It ran but not very well. I downgraded to a 65MM MAF and the new style 19 lb injectors and it runs great. If I ever get around to reprogramming the ECC I might try the 24lb injectors again.

Random MAF and injector combos are not known for running good. Key is having a computer matched to BOTH the injector size and the MAF transfer function. With a stock 5.0 upper there is a good chance you are choking the airflow enough that 19's will work just fine.

 

[73azbronco]

as mathmatically shown on other threads, standard duty cycle for 19lb on a 351 to 5000rpm is well within 80% duty cycle, so unless you will be running above 5000rpm, 19lbs will work fine.

 

[Bronco_69]

i run 19's on a 351w with gt40 heads, 5.0 cam, and edlebrock intake. it is fine. the issue would be if you were running WOT at a mud bog you may be a little lean if you really wind it out under load.

 

[Broncobowsher]

True, 19's will work 99% of the time. But that one time when you have your foot buried in the throttle passing someone and you are wringing the motor out and it suddenly leans out on the top end and you discover that aluminum actually is a combustable metal under the right conditions. That is not a good time to think bigger injectors were a good idea.

 

[HoosierDaddy]

True, 19's will work 99% of the time. But that one time when you have your foot buried in the throttle passing someone and you are wringing the motor out and it suddenly leans out on the top end and you discover that aluminum actually is a combustable metal under the right conditions. That is not a good time to think bigger injectors were a good idea.

Awesome examples ....