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What Are The Pluses of Bigger Fuel Injectors?

new 1/20/2004,updated 1/21/2004

Simply put, you need a certain amount of fuel for a desired engine output (HP), if you plan for mods then they may or may not be required.

If one uses 0.5 for Brake Specific Fuel Consumption (range 0.45 to 0.55 for NA) and 80% duty cycle on the injectors (best to stay below this % on extended durations) then you can use the following: 
HP * 0.078125 = Flow rate (lbs/hr) [use .0703125 for 0.45 BSFC or .0859375 for 0.55 BSFC]

235hp = ~18.35 (we have 19 lb injectors stock)

250hp = ~19.53 

275hp = ~21.48

300hp = ~23.44

You can see how with running NOS kit it can easily cause one to run lean...Kirks 24lb injector mod is right on!

Don McKinnon
96 Black - Borla
Our thanks to Don for putting this together. Wish I knew what it meant:{-


The stock Gen 3 Injectors will flow 23.99lbs per hr at 100percent duty cycle.
Info was found out buy a leading injector Bench flow company when I had my 19lbs set bench flowed and tested. 


This is very good. Only one question. Of all these injectors (site #2), none of them lists the SHO as an application. (not a surprise)

1) Do the SHO fuel injectors share application with another vehicle? Or are they specific to the SHO? 

2) Given that SHO specific injectors are not available, do these other applications fit correctly? What modifications are required to achieve a proper fitment? ( know Kirk knows the answer to at least one of these questions. ) 

3) I am sure I missed this information some where else along the way for not paying attention, so... Is this information on the website? ( I looked for it) 

Al Primm


I have purchased EVERY type of Design 3 injector available (about 2000 dollars in useless research). There are No direct replacements, there are some that will fit but they are too long which require machine work to the IRM to make them fit further down in the manifold so the fuel rail will bolt sown and hold pressure. 

The Gen 3 SHO of course uses a special injector that is 3/8 to ½ inch shorter, I believe from some conversations on the forum that Carter may have some installed as well but I think he is zip tying the fuel rail down. ( I could be incorrect because it was along time ago) 

As far as making them fit, any good CNC place should be able to make the holes correctly, there is a weird 26.6 degree angle that need to be made to accommodate the larger injectors and need to be milled down to the proper length. There are 3 sets hat are done now that have both larger injector holes and BBB’s. I have one and I sold Brad At SHOFAST the other two, one set for Mikey B and the other set for him. One set is due in for another person in OH fairly soon, he is using the Blue injectors from 5-oh Motorsports, the ones that he was told were direct replacements but their not so Buyer beware.



Be aware that the V8 SHO has a very unique length fuel injector. Going to these sights and ordering $300+ worth of fuel injectors that are listed to fit the SHO will not always get you the right injector. Be very careful and order the from a SHO supplier or be prepared to be sitting there with 8 un-useable injectors. This one for instance, "F5DE-24lb" though listed for the 89-99 SHO, is almost 1/2" to long to get the fuel rail on, and no, you can't put spacers in or twist the rail. 

Carter Fuji 


OK. thank you for that clarification. 

now, another question, or two. 

The only source for bolt in injector replacements is FudMuckOh. 

I am hearing two things on the 'OTHER' kind. 

A) There are some models that will physically fit the manifold, BUT, the fuel rails wont fit on the injectors. 

B) There are some model injectors that sorta fit the manifold, but the insertion angle (measured where?) is off and something needs to be milled. 

Ok, working backwards, *In my best Economics Professor voice* "Assume we have an injector that can physically be attached to the intake manifold" 

1) what about an alternative fuel rail set up? Is this doable? I honestly havent looked at it closely enough to really understand how it fits together. 

2) Is a hard rail (no rubber hose) required? Perhaps a combination of hard and soft parts... anodized aluminum rails with rubber connections to the individual injectors. 

I know something would have to be done with the FPR, too. 

Im just trying to think outside the box here. 

Next week, we begin on INTERCOOLERS.... 

Al Primm 


There is NO benefit to just installing bigger injectors.....in fact, it could hurt. It's like just throwing bigger jets into a carburetor. Just giving more fuel accomplishes nothing.

Actually, all SHOs are set on the rich side under WOT, and a stock setup actually can run better if leaned out a bit at WOT.

Ron Porter


The larger injectors are good if you have a power adder.. IE Nitrous for the Gen III. if your not using that or Like Mikey or Carter have a blower don’t waste your money on it. The BBB did make a gain as you can see from my Dyno charts on v8sho.com   

Easiest way to get a higher output would be an adjustable FPR and play with it until the car is on the edge of stalling.. Again useless unless if you have Nitrious.


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