I have Holley Projection 4Di with the 900 cfm 4 injector TB (85#/hr). According to Holley this should be good for a motor making up to 500 HP. I had my machinist dyno the engine and it made 465 HP with a 4 barrel carb (750 cfm)

I am wodering if an an oversized TB would effect overall performace like a CARB would. Would this even matter if my fuel maps were done correctly?

My best ET to date is 12.49 @ 105.25 with a 1.75 60' (57 degree day)

My best 60' to date is 1.61 at a slightly slower 12.61 @ 102.11 (on a 95 degree day!!)

My car weighs 3705 with me in it.
Based on my vehicle weight, flywheel hp and 60' times (1.6X)I have run this scenario on my Drag racing software and the car should run high 11s.


[This message has been edited by FRMULA (edited November 14, 2001).]

 

I'm no expert but I know that I would do it just to do it. I'm one of those guys that thinks I can get anything to work. If your pumpshot and VE tables are fine then there shouldn't be a problem. The reason carbs loose power is the difference in air velocity. They require the air velocity to control fuel flow. EFI doesn't have that problem. Like Holley said, it's good till 500hp so why wouldn't it work on an engine making 465! Besides, any EFI can get away with more cfm, it's one of the advantages. Just look at the crazy big blocks running dual dominators. Most of the time it won't total more than 2000cfm. The same engine can be equiped with EFI and run dual 1500cfm TBs! Go figure. It will take a lot of tuning so don't think it's bolt on and go fast.

 

sounds like your carb may be giving an off idle lag problem? with that 60' Either that or its not enough cfm. But like jon said, with efi, we always want more cfm, and thats ok.

I agree, if i were you, i would do it, once you get it tuned, you will have better milage, and economy, and you will probably gain a few horses, because of eficiency going up a bit, because of better fuel atomization, but that will take some tuning.
You should be able to get it to run with at least the same if not more power with the efi setup. It will just take some fun tuning time. Good luck, let us know how it works

o, and to restate. you wont suffer any power loss with going to higher cfm with efi. velocity may go down, but just think, the nice atmospheric pressure is going slam into those cylinders faster.

o, another thing i just thought of. Your throttle response will increase a lot too, so you may have to relearn your launch.

[This message has been edited by snflupigus (edited November 15, 2001).]

 

Those runs were made with the Projection NOT a carb.


The CARB was only used on the Dyno since I did not have the time and motivation to hook up the Projection for the Dyno.