1991Z07

I've got my 427 back on track.

The build is:
427 CI - Dart block w/wide pan rails
Brodix M2 T1 227 heads (mine have been flowed at 321 CFM on the intake)
Jesel split ratio shaft-mounted rockers (1.7:1 intake, 1.6:1 exhaust)
Custom cam (.760" lift at the valve, don't have all the info here as to duration, overlap, etc.)
Crower forged RoadRace crank
Crower billet rods
12.5:1 forged blower pistons (yes...I can say HIGH octane please)
A custom FI manifold (Victor Jr. intake with fuel-injection added) completely CNC ported.
Belt drive for the camshaft
Canton custom road-race pan
Wet-sump system w/ (2) 2-quart Canton AccuSump's in parallel.
McLeod Street-twin clutch.

Planning to run it on E85 or VP107 fuel, so this will essentially be a race motor only (autocross/track and open road races).

What do you guys think is an ideal size throttle body for this motor? Should be ~ 725 HP/675 lb.ft. according to the machinist who has built 10 of these monsters before...just never for a Corvette

Think a ported ZR1 63MM would do it? That's what Lingenfelter uses on his 415 CID LT5 packages...

tpi 421 vette

With the build you have, I would go with a Monoblade. They flow 1350cfm.

Kubs

I am going with an 80mm LS1 throttle body on my 355 single plane EFI 355ci. I have heard the single blade throttle bodies have a better throttle response too. Since you would have to fab you rintake elbow anyway just make it fit an LS TB. I would look for a 92mm or even 102mm LS throttle body for your build.

dizwiz24

Im running a monoblade on my FI heads/cam/LT headers, stock bottom end lt1.

Street manners of that piece is great. Of course you mentioned race only, so that may not matter to you.

One issue I did have was full travel of the gas pedal only opened up the monoblade about 75%.

Even after adjusting the throttle cable sheathes, on my 93, the best I could get was maybe 85%.

Ive heard about some people bending the gas pedal to make it 'pull' further, but I didnt like that idea.

What I did, was got in and messed with the cams inside the 'ASR' box on my '93. I added screws to the pulley for the throttle body to make it effectively bigger diameter than the other pulley.



Also, be sure that you are real clear on everything you need (and that they are clear also), as the gentleman at AS&M can be cranky and difficult to work with.

In my instance, I told him I had a '93 vette and needed a monoblade. He sent me a monoblade TB for a 94 thru 96 vette. The difference is the IAC adapter plate. 92-93 take a screw in IAC, and 94-96 take a bolt in IAC. I shelved the unit for about 9 months and when I took it out discovered that it was for the 94 thru 96 car. Anyways, he acted like he'd change out the IAC valve as an even exchange but in reality charged my about $38.00 in restocking fees between getting the correct IAC valve and the one I returned (with me paying shipping to send the old one back). When I pointed this out, I got an email stating that I was lucky he was even doing anything since it was 9 months after the initial sale (his mistake though for not sending a '93 unit out).

Despite all this, the monoblade part is top quality and Id recommend it. It is that nicely finished of a piece !

USAsOnlyWay

I've got an Edelbrock 90mm LS style monoblade on mine. I had to switch to a Lokar cable to hook it up (linkage wise, it was cleaner than messing with the old stock one that needed to be replaced eventually anyway, but you could just get the right LS style barrel end and cut the linkage off the stock cable and use it, if the length is right) but I get full throttle action with the stock pedals in my 86 and it is plug and play in terms of connections with a pair of connectors from FAST.

I'd definitely look at 90+ -102mm TB.

1991Z07

I just found the flow numbers for the 63MM ZR1 to be 800 CFM. Not nearly enough.

Kubs: I saw your thread on the LS throttle body. Did you go with one that isn't servo-controlled? I'm guessing I'd need a 103 MM one for this build. My motor matches up pretty well with the new LS7 heads,

Lift Intake Exhaust

.300 246 cfm 174 cfm

.400 302 cfm 200 cfm

.500 343 cfm 211 cfm

.550 358 cfm 216 cfm

.600 360 cfm 220 cfm

.650 379 cfm 224 cfm

I'm about 50 CFM shy of their flow numbers.

The LS throttle bodies flow:

90mm Throttle Body 1170 CFM

105mm Throttle Body 1520 CFM

4500 Throttle Body 2008 CFM

(taken off Wilson's web site).

How about this baby?



The Wilson 4500...available in 1388, 1484 & 2008 CFM versions. Linkage available in 1-to-1 or progressive. I'd just need to build a hat to go from it to the bellows intake.

Hmmm...I need to talk to the machinist again.

dizwiz24

Ahh!

I forgot to ask a key piece of info... what intake..

if its a carb style intake, then forget my comments about the monoblade above!!

Roocars

Hi 1991Z07

I use a ported Edelbrock victor-e with a willson 473187P this flows 1388cfm and is progressive. It works grate for me on a 421 but I don't flow the type of numbers you have. What you need to try, is check the manifold vacume on the engine at WOT, see if you can get it down into the area of .5 inch of vac. You should be close to the right size. Your engine builder will know from experiance what works best with your set up.
Good Luck
Brian

mseven

you might want to check these guys out:
http://www.accufabracing.com/throttle_bodies.htm

Kubs

If you look for one made for LS1 F-bodies like the Camaro or Trans Am, or the GTO (2000-2004 era for all t hose cars) They are all cable driven. since stock throttle bodies for the LS1 are only 75mm, just look for aftermarket parts for a newer Camaro. I believe FAST makes a 102mm cable driven throttle body for LS engines. I found mine on eBay for about $85.

1991Z07

Engine builder said the last motor like this he did was set up for twin-turbo, going into a '57 Chevy. They used the Wilson 4150 and with 10 lbs. of boost were making 1000 FWHP on the engine dyno. Once installed with inter-coolers in the car, they are making well over 1200 HP (not sure where they are on boost...turbo's will go to 20 PSI though).

He says the carb-style will give better throttle response. The 4150 flows 1136 CFM.

If I went with an LS-style, it would need to be a 90MM minimum, and most likely a 105MM.

I can't do the 4500-series...I'll need a different manifold. I spent too much money on the one I have now, and it isn't even being used yet. I think the LS-style will be easier to fabricate a transition to the bellows, too.

Wilson has some REALLY nice adapters for this:

Cast:


A little polishing and a clear powdercoat and that would look sweet!

Especially with one of these attached to it...

Kubs

yaowza! I just saw the price tag for that throttle body. My $85 used eBay one isnt looking so bad now...

Im surprised to hear they think it has better throttle response. I would think moving one stream of air would be easier than 4 or even 2 little ones. Im curious to see the outcome of this.

1991Z07

I hear 'ya!

I've spent a bunch on this motor just in parts...I figure another $1000 won't kill me now.

I think I'm leaning towards the LS-style more. I certainly like the different look the LS throttle-body will give it. PLUS the 105MM flows a bunch more than the 4150 carb style.

Either the LS, or a mono-blade...the mono-blade falls right in the middle of the 90MM & 105MM LS throttle bodies. If I use the mono-blade and build a sheet metal adapter to go from the carb plate on the manifold and attempt to get the LT-style throttle body in the "stock" location I could use the stock bellows for fresh air.

Good thing I have some time to think on it...

88BlackZ-51

that was one serious build. goodluck with it!