Steve Zuckerman

Hi Guys,
Does anyone know the CFM rating of the throttle body injectors on the 575? I think they are around 670 CFM, but would appreciate the correct information.
Does anyone manufacture TB injectors of a higher CFM rating that can be run off the the MEFI 3 computer (preferably), or other another computer?
Can anyone modify the Merc injectors for higher flow rating?
Thanks,
Steve

thunderusone

Steve, according to whipple, the stock injectors in the throttle bodies will only support 715 to 720hp max. Even at that level, the injectors are operating at 100 duty cycle burning the injectors up. I believe somebody makes a low impedence injector with more lbs/hr than the stocker but the the problem is availibility. I have a buddy in AL that has been trying to get them for 6 months now. Keep in mind that if you do get a bigger injector...you next problem is now going to be the throttle body cfm running out. The most HP I have seen out of the gm truck tb set up is the 675 KE's that were in Bruce's talon. We turned them up...they were 540's and went to about 760hp with them with 8-71's and chillers. The problem with them is that they would not idle for chit....it was like slinging numb chucks around the dock (Programming). They had bigger injectors in the same TB's that you have BUT they were a different impedence driven off of a DFI ECM.....which is totally different than the MEFI that you have....so that won't work either. So, if you are planning on going on up significantly in HP, a whole different setup is probably on the drawing board. Good Luck!

Steve Zuckerman

Hi John,
I guess we will see what we can get out of them before going on to something else. RB's boat has never run better with a similar setup, so we have a good baseline to go by. However,
I agree that it's "restrictor plate racing" , as RB says.
I am looking for EFI alternatives and have found a few. Holley has a 1000CFM, 4 barrel TBI, and I've seen some intersting HP aftermarket stuff on the internet. I really don't have a problem going to carbs if necessary. Your boat is certainly running very well with them. I would like to keep the EFI for easy starting and idleing characteristics.
To be continued.....................
Regards,
Steve

Whipple Charged

That injector style is junk. There basically wide open at 650 unless fuel psi is upped, via boost or mechanical adjustment. Then they're just mechanical nozzles. Those injectors are so incredibly sensitive, they're nearly impossible to get just right unless you calibrate them on the fly, or your doing the exact same thing everytime.

The throttle bodies are off the GM 1995 454 TBI engine. The cool fuel system is also taxxed at the 700hp range as well. Then the SC, it's not made for high rpm, so it won't live at that range. In general, it's just too darn small in all areas. If your stuck on running roots blowers, and TB injection, then put a TBS blower on there, and get the Wilson 4500 style TB's. You can also get fuel rails from Wilson or BDS.

Thanks

Steve Zuckerman

Hello Dustin,
I am definitely out of blower, so the 256 is gone. As far as blowers go, it comes down to you (a 3300) or TBS (an 871). What is the retail on your blue 3300 EFI system?
I'm not allergic to carbs, so that may be the obvious answer.
I rode in friend's cat Sunday, with carb N/A 540s. Idled like a kitten, started right up, everything EFI does.
Thanks for heads up on the Wilson TBI. I had not seen their stuff, which looks very iteresting.
I saw your new Eliminator at the LA Show in February, man what a badass boat !
Regards,
Steve

Young Performance

Steve,
You keep bringing up RB's setup but ya'll don't have the same motors. You are going to a 540, which is almost 10% larger than his, with a much larger cam and much better heads. Your motor WILL NOT run with RB's program. Even if it did, it is not going to make the power that you are looking for. Most of RB's speed gains have come from setup changes(nose cone, props etc.) From what I understand, he has not gained much from just the engine mods.Maybe just a couple mph. There is nothing wrong with that since he hasn't really done a lot to the motor. I doubt he is making 650 hp, which is great for what he started with and the few changed he has made. However, I seriously doubt that you will be very happy with 650 hp. As I told you on the phone, I don't think an un-intercooled 8-71 is the answer, and definetely not with the current injection. Even an intercooled 8-71 is going to reach it's max WAY before the Whipple does. I gave you my opinion; put on the Whipple and be done with it. No it's not the cheapest way to go, but I do think it is the best. Not to mention, that's the only shot you have to even stay close to that orange boat. Just don't want to see you make a mistake.
Give me a call if I can help you in any way. See ya, Eddie

thunderusone

Oh Chit.....

Whipple Charged

Steve,

Theres one other company that makes carbs that have fuel injectors inside, pretty trick setup too, but can find where they are. Never used them, but it's another option. But the Wilson stuff is top notch.

Our 500hp efi stg2 system is $9299.99. That comes with injectors, pump, regulator, fuel cooler, manifold, intercooler, ECM recal, etc. It's by far the most expensive, but it's got as much capability as any 871 and will be about 2 feet lower in profile.

Thanks for the compliments on the boat, it's a bit toasty to walk in, with the black graphics, but it's sure fun to drive.

Thanks

Young Performance

Boss EFI has the carb setup with the injectors inside. You would have to run two of them because the only hold 4 injectors each. I looked at them but they are very expensive and only want to sell the entire package (ecm, harness, carb etc.)

Ihave also used a roots with (2) 2000cfm throttle bodies with an injector plate under the throttle bodies that I made. The injector plate was only an inch thick and could be made to hold as many injectors as you want. Just bought some extruded blank fuel rail and drilled the holes with an injector bit. Once again, the problem is height. I don't think it will be any lower than a carb by the time you add the throttle bodies and the plate to the blower. It worked very well, but with an intercooler, I'm sure it won't fit under the hatch.

Eddie

Steve Zuckerman

Thanks for your input everyone!
Steve