Doing my research, advice and thoughts wanted

Stew Jones builds V-12’s for E-Types, and we use to have Claiborne (sp?) on this site who built a 170mph XJS.

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You probably are referring to Chadbourn_Bolles. This guy:

He has not posted on JL in awhile though

Try his website.

Whats the diameter of those ITB’s?
Link to the build thread?

If you want to find out the best options for the V12 and spec you want, talk to Rob Beere in the UK.
Rob has been building V12 for years as well as the 6’s so should be able to tell you how to get 350hp.


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45mm V12 XJ6 Conversion Build

45mm in diameter of the blade? (inner diameter) any particular model of year to look for ?


I believe so. they come from 2006-2008 ish BMW K1200 Bikes here is one of the listings I bought. I only have 8 right now planning on getting the last 4 soon if a set popup for the same price.

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DriftWorks on youtube used 2 sets of E46 M3 itb’s for his V12 Murcielago. but they have oval ports that are much larger.

The price on the M3 TB are just ridiculous like the Jenway setup…

Ill probably go for the BMW K1200 as the price on a set of tb x 3is really nice and 45mm is enough for me :slight_smile:

Can you measure? What I find on the internet is that they are 38mm inner diameter…

Bill, it’s much easier to make extra HP with the early engine. The HE head has pocketed valves and you can’t go larger.
The early engine can take a1.75in intake valve, 1.63 std. (leave the exhaust std.), and with porting of both intake and exhaust ports you can easily get to 350HP with a mild or even stock Cam.
TRW achieved 450HP+ from the early engine with std. valves with comp cams.

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I was thinking, looking at the flat-head engines, custom pistons with a tight squish area around the outside and a nice bowl for the combustion chamber, say around 10.5 compression, should do quite well.

Greetings All,

I’d probably go with the Beemer. Easier and cheapervto get horsepower out of it.

Not sure where the tranny will come from likely a T5.

Yes, I’m thinking T-5 for the trans.

One difficulty w/BMW engine is the huge front sump.

Greetings All,

Jag V12’s last I knew, pretty easy to come by. BMW’s, have no knowledge.

Ferrari V12’s have the intake in the V. Jag V12 from the carb era have intakes with spider tubes. Now if you could line up either some throttle bodies or Webers in that V, you could achieve that look.

Vette is pretty heavy as they design it knowing the 'glass adds nothing to structural rigidity.

Not precisely true: it does add some, and from the C5-on, got better.

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A Vette weighs 3300 pounds. A Factory Five Type 65 coupe with the same engine, tubular chassis, and fiberglass body, weighs 2400 pounds. I dunno where the Vette puts the extra 900 pounds.

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Greetings All,

If you have followed the Corvette, the fibreglass body has always been a bone of contention.

Unlike unibody construction, the Corvette’s body adds NOTHING to rigidity. There is steel added to keep body flex from occurring. Sort of reminiscent of the first aluminum bodied 120’s. There were not a lot of weight savings due to having to reinforce the structure to keep the aluminum from rippling in areas.

While GM put the Corvette on a diet, it is still a heavy car, considering its competition. That 'glass body is the reason.

2019 Ferrari 488 GTB weighs 3252

2019 Corvette coupe weighs 3298

And the fiberglass does add rigidity. Has sine 1984. Before that, you are correct.

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