What size throttle body is recommended for a centrifugal supercharged big block with 1000 + hp range. The majority of the systems that I see are either 1000 or 2000 cfm. Not too much in between. ATI suggests a 750 cfm carburetor for up to 900hp. This would mean that the normal supercharged carburetor CFM formula does not apply to a centrifugal? My 383 with a roots has 1200cfm in carbs? I would think a 500 CI range with a centrifugal would need at lest 2000cfm.

Thanks

Tom

Just how far into the 1,000+ hp range do you want to go? Fuel injection throttle bodies do not have to worry about mixing fuel, so the cfm ratings seem large vs a carb. The 1,000 cfm size should work mint into the 1,000 hp range. The 2,000 cfm would probably be needed from ~ 1,400 hp on up. One thing to remember is that on any blow through application the throttle body will be flowing well beyond its n/a rating: my 468 blow through uses an 830 cfm Holley, at max boost of 17.1 psi it is actually flowing in excess of 1,700 cfm. I'm sure you already plan on running an intercooler, a fuel injected blow through needs it because an efi blow through does not get the "mini intercooler" effect of a carb atomizing the fuel - my under carb air temps are 40+ degrees cooler than above carb air temps.

Thomas

A thousand at the rear would be nice. Your numbers are very impressive. Very nice job. I picked up a complete 454 for $300 last week. It is looking like 468, 496, with a roller cam, a single plane, and injection. Same heads, or AFRs, w/8:1 comp. I think a Scat 4340 Crank will be more than enough but I may go Oliver on the rods. I'll run an intercooler and as much boost as I can.
I do have two questions though; When you posted your dyno numbers your cam dur is 232/327. Is that correct? It seams pretty big on the exhaust. If you would do it again would you go 4.25 stroke?

Thanks

Tom
graemlins/thumbsup.gif graemlins/thumbsup.gif

My SC 468 cam duaration is 232/237 not 232/327.

What class/series are you planning on racing in? 1,000+ at the rear wheels will propel your '69 into the 8.8x second range at ~ 160 mph.

For your bottom end components you have many ways you could go. Bear in mind that the more you spend, the less maintenance you are likely to have. What I mean by maintenance is things like how often the oil pan will need to come off for a bottom end inspection.

More stroke would not be useful, outside of a marine application for instantly popping a boat to plane from a standstill. All the added stroke will do is to move your hp and tq peak rpms down the scale. Think about it: there are legions of supercharged / turbocharged small block Henry 5.0 and stroker 5.0 347's that make well beyond 1,000 hp in race trim. If they can run the number using a 3" stroke, then it is boost - not stroke - that is the deciding power factor.

If I were building an engine to make power beyond what my 468 made, my preference would be to use one of the aftermarket blocks rather than a standard production block. The stronger your foundation, the more reliable and long lived your final engine will be. Spend a little more now, and protect your investment - I could do it cheaper a second time, my SC 468 rang up ~ $14,000 start to finish.

Thanks for the compliment, it made more power than I had expected. If I had known it would power up the way it did I would have made some fuel system changes to bring it over 1,000 hp - we shut it off early at 5,800 rpm because it maxxed out on fuel supply. As it is I do not really plan on running it at the 17 psi level, I'll have enough problems getting it down the track at the 10.5 psi power level.

Thomas

The 468 is a more efficient centrifugal combo than say a 540. I did make more torque with the ProCharged 540 than the ProCharged 468 but not much more power. There's just too much lost in the extra weight and drag of the larger rotating assembly.

I made 828 rwhp while blowing the inlet tube at 5500 rpm. This was on 91 octane and no intercooler, plus a small 3" street exhaust. Probably would have made 900 rwhp or so at 6500 with the tube splitting. On race gas and a bigger exhaust/more boost there was a lot left in this combo.

That was with a 75mm monoblade, maybe 900 cfm or so. So a 1000 cfm t.b.will take you well over 1000 crank HP. I agree with Thomas, and if you're looking for 1400+ I'd opt for the dominator based throttle body, or one of the larger monoblades.

Jody

I just snagged this throttle body off of ebay. Not the auction but same thing/guy. Hope it will work.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2445005301&category=33558

I also need to keep an eye out for a bare edelbrock pro-flow manifold. The injector position looks like they are on a more efficient angle.

Tom

That looks to be a mighty fine throttle body - you are on your way to making crazy hp smile.gif Select your cylinder heads before you select the manifold. Port location and shape will then dictate your best manifold choice. Do not rule out adding injector bungs into a non efi manifold.

I still have no idea what your ultimate car plans are: race or "cruise". If you make over 1,000 rwhp then it won't be much of a street car no matter what you might be telling yourself.

Just curious, why efi? I'm biased of course, but I actually think a carb has more positives than efi when "boost" is under ~ 20 psi. I say "boost" to emphasize that it is not the actual measure of the pressure output of the supercharger, rather it is just a measure of backed up flow in the intake.

Thomas

Originally posted by Kx69:
I just snagged this throttle body off of ebay. Not the auction but same thing/guy. Hope it will work.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2445005301&category=33558

I also need to keep an eye out for a bare edelbrock pro-flow manifold. The injector position looks like they are on a more efficient angle.

Tom Ah, that's my friends stuff! Dan and Eric Fodge do those throttle bodies. Had one on my yellow ProCharged car before the mono-blade. Works great and is 1/4 to 5/16" shorter than any of the others I could find (hood clearance was at a PREMIUM)!
Jody

Thomas, The car will be a race car, but not trailer. I would like to try something other than a carburetor, I spent too much time messing with my two holleys on my small block with a roots. As for the intake unfortunately the new edelbrock are only 4500 flange, so it very well may be non injection.

Jody, I tried to find some info on the web regarding fodge engineering, and got nothing. Is there a web page with there other products?

Thanks

Tom

I suppose I am pro-carb because I only had one bad experience, the rest was all good. The first place that reworked my carb made all the right "talk", but their finished product failed miserably. So I hijacked my carb back while no one was in the dyno room (shop security changed after that smile.gif - and I further hijacked my whole engine to finish tuning at Vrbancic Bros Racing), the work that http://www.customcarbs.com did was incredible. The newly reworked carb only started to run a little out of range when the boost went past 16 psi - and that could have easily been taken care of if I wanted to do further tuning at that level. I had only specified that max boost would not likely exceed 15 psi, so the fact that it still worked well beyond what I had specified speaks well of their work. Everyone has their favorites of course, but I believe that no one does blow-through carbs better than The Carb Shop.

Are you planning on using this car to make your license passes?

Thomas

Originally posted by Kx69:
Thomas, The car will be a race car, but not trailer. I would like to try something other than a carburetor, I spent too much time messing with my two holleys on my small block with a roots. As for the intake unfortunately the new edelbrock are only 4500 flange, so it very well may be non injection.

Jody, I tried to find some info on the web regarding fodge engineering, and got nothing. Is there a web page with there other products?

Thanks

Tom Tom, they had a website, but they're converting from EFI sales and installs/tuning to more of a developer/manufacturer role. You should call Eric at (916) 851-9111 and see what else he has. They had quite a bit of EFI stuff they were clearing out.


Thomas,

There's nothing wrong with a well-prepped carb at all. I've had three blow-through carb deals that ran excellent once I got smart enough to let a pro handle the mods!

Jody