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Thought I'd start a thread here on a subproject of my main project, which is rebuilding my 550 Maranello engine to be a 6.0 liter semi-hotrod motor.

I had picked up a 456 intake manifold awhile back, with idle thoughts of trying an ITB conversion on the 550, more for the bling factor than performance, as the 550 manifold with its variable length tract is proven to flow better than the earlier, fixed tract 456. However, no one's tried a 456 manifold with an ITB conversion, so it may turn in some respectable numbers. And of course, it certainly tops the 550 manifold in the "cool" department.

So here's a stock 550 manifold, and the center plenum is the variable tract mechanism. Under that cover are 12 butterflies that open up at 5500+ to let the motor breathe better on the top end:



And here's the 456 manifold - no center plenum, just the cross ram setup:



So I lopped off the side plenums on the 456 manifold, took stock of my GSXR ITB's from an old project and here we go. Hopefully one day, this pile of parts will become an ITB setup that I'll use to break in my 550 motor on a buddy's engine dyno here in Houston:



As soon as Mark can find some time to work his magic on these non-concentric runners, and weld some stubby pipe extensions onto them and blend things in so everything is concentric again :



Unfortunately I don't have a proper shop, nor any machine tools or welding equipment, so my updates to this will be a bit slow in coming. Anything that requires more than a cordless drill or a propane torch, I have to farm out, unfortunately

Fancy!

Cool project, now I'm going to throw a wrench at you Take a look at the BMW S62 ITB's, I've been very tempted to utilize them on a ferrari engine for a awhile now. I think the Porsche guys are using them now too.

I already had the GSXR TB's from a previous project, so I'm going to use them as a "proof of concept" interim solution, then I'd planned on going to Jenveys for the permanent solution. But those S62 ITB's are nice and compact, so I might have to rethink the Jenveys (which are currently running about $210 per TB, not including linkages and trumpets.....)

Toyota also made some ITB's for their 4AG engines (think Formula Atlantic) that are cheap, robust, but not nearly as compact as those S62 ITB's.

The great part about the S62 setup is that they are on a common shaft and can be set to any centerline! That's what makes them standout for me. No fiddling with interconnected linkage. Also the bore goes from round to oval while making a turn, 5-axis milling required if your not casting them. And they're reasonable in cost on the second hand market. I should stop before you all start buying them up and the prices climb before I can get a couple sets.

Another decent source for ITB's is down in OZ, EFI hardware. more of a real kit/DIY but not bad. Not as clean as I'd like but for true custom stuff the price point is good without spending loads on casting or 5-axis mill work.

Wow......I didn't realise they would fit any bore spacing without mickeymousing around with linkage extensions - that makes them even more attractive. Not thrilled with the round to oval transition, but it would be good for those who want to do a direct-to-head setup or a shortie manifold. For my crossram setup I need a straight through, round to round fitting.

Buddy put this EFI Hardware setup on a 1UZ Lexus motor - they do make some real nice stuff. Most of the go fast parts for my 1UZ's come from Oz or NZ.

OK, you're keeping the stock port runner. I thought you were replacing the entire setup as the intake port on the head is an oval.

EFI hardware does have single TB's 803 series, that could be fit to the end of your cross overs. Not cheap though when you add up 12!

Another option, and I know you're trying to utilize what you have but it's fun to throw things out there.

have a plate gun drilled for the throttle shaft then bore the holes. You can have each bank done in one big chunk all sharing the same shaft. Be far less then buying 12 ITB's. Hey I think Marks slowing down looking for more fun projects, let's ask him!

While it's tempting to do a direct to head setup, I became intrigued with this crossram configuration awhile back, and I think with the proper plenums over the bellmouths and inlet ducting, I could reassemble the system with the stock air intakes, air boxes, and possibly even the MAF's for when it's inspection time. Then after inspection, it would take all of 10-15 minutes to remove the stock inlet piping and revert back to open trumpets (well, open with foam filters on the ends)

I agree, it's fun to consider some alternatives, however

Since you did Nick's cam belts & drives, I want to bounce some cam belt ideas off you, but will do that in another thread.....

Can the 3.5 V8 throttles bolt up to the V12 heads?

Dunno - what are the dim's of the 3.5 ITB's?

The V12 inlets are a 28 x 47 oval (that's the actual inlet port size, not the flange size), with studs on 73mm centers