308 V12 conversion begins

Reproduce the deck lid in fiberglass, and install a piece of Lexan so you can see that magnificent V-12! Use epoxy resin with the 'glass though, it's much easier to work with.

Shiny Side Up!
Bill

 

Not to hijack the thread

I like this idea too. Has it been done before or has the cost scared folks away from doing it?

Can a autobody guy handle somthing like that?

 

Mark - The TBs you have may be OK!!

I've copied some info from www.jenvey.co.uk

It suggests that you should be OK with 42mm TBs on a 'well proportioned system', as you're looking at 58bhp/cyl

''What is the best throttle body diameter?
Factors influencing size are; Power output, RPM, cylinder head design, cylinder capacity, position of the throttle body in the inlet tract and position of the injector.

Choice of bore size is a balanced compromise resulting from the following;
1) A larger bore leads to lower flow resistance, but obeying the laws of diminishing returns.
2) A smaller bore leads to better throttle control and response (never underestimate) and improved fuel mixing.
3) The system should be considered in total - from (at least) trumpet flange to cylinder and proportioned accordingly.

Basic references for BHP per cylinder, assuming ca 120mm (misprint for 200mm - see below - 246T) from butterfly to valve head and a max of 9,000 rpm are;
Up to 30 - 30mm, up to 33 - 32mm, up to 39 - 35mm, up to 46 - 38mm, up to 51 - 40mm, up to 56 - 42mm
Up to 65 - 45mm, up to 74 - 48mm, up to 80 - 50mm, up to 87 - 52mm, up to 93 - 54mm.
These power figures may be increased by up to 10% in a purpose - designed and well proportioned system.
As butterfly to valve distance increases, butterfly size will need to increase in proportion to system taper and vice versa.
Lower revving engines and those with injectors placed before the butterfly will generally accept a larger body.

What is the correct overall system length?
Induction length is one of the most important aspects of fuelling performance engines.
In our experience an under-length system is the greatest cause of disapointment, with loss of up to 1/3 of power potential. There are a number of good books on the subject and the serious developer is referred to these and, in particular, dyno trials. A guide figure, from the face of the trumpet to the centre of the valve head is 350mm for a 9,000 RPM engine. Other RPM are proportional, i.e. for 18,000 RPM the figure is ca 175mm.
Any air feed system to an airbox or filter can have a large effect on the power curve and must be considered carefully - particularly if the airbox is small.
The induction system is part of a resonant whole - from air inlet or trumpet to exhaust outlet - and the ideal length is heavily influenced by the other components.

What is the best position for the butterfly?
The butterfly is an important aid to fuel mixing. When positioned too close to the valve this advantage will be lost whilst positioning far away may lead to a loss of response.
As with the injector position (see below), higher RPM demands a larger butterfly to valve distance. A practical minimum figure for a 7 - 9,000 RPM engine is 200mm, whilst the maximum is dictated by the need to fit an air horn of reasonable length to achieve a good overall tract shape. One solution to this apparent compromise is the use of bodies with fully-tapered bores which, in effect, extend the trumpet distance beyond the butterfly and into the manifold. For very high speeds above approximately 15,000 RPM, the ideal butterfly position is only just inside, or even outside the trumpet and a point is reached where a taper is no longer sufficient for good tract shape. For these circumstances we can supply bodies with the exponential trumpet shape machined into them as a special service, or barrel bodies which, by their nature, must be purpose-designed in conjunction with the cylinder head.

Where is the best place for the injectors?
Where one injector is to be used per cylinder the best compromise position is immediately downstream of the butterfly. This gains maximum advantage from local turbulence and gives results surprisingly close to the optimum at both ends of the rev-range. This is the recommended position for most applications
For performance at low RPM, economy and low emissions the injector needs to be close to the valve and firing at the back of the valve head. This is the favoured position for production vehicles.
For higher RPM (very approximately 8,000+) the injector needs to be near the intake end of the induction tract to give adequate mixing time and opportunity. The higher the RPM, the further upstream the injector needs to be. As a result, use of speeds above approximately 11,000 RPM may give best results with the injector mounted outside the inlet tract altogether (see our remote injector mounting). It is common to fit both lower and upper injectors in such a system to cover starting and low RPM as well as high speeds. ''

 

Oh, I didn't check and thought you were only after 700bhp not 750!

I also didn't realise the TBs had to be so much further away than 200mm. I guess they interfere with each other if you put them at 200mm?

You've no doubt seen Jenvey's prices. You should be able to get 10% off (I do) which gives £116= $204 per 52mm TB. I guess this is way over budget?

The other alternative is to make your own slide throttle assembly, which with modern seals and rollers should be perfectly reliable for the road, and will look very sports-racing. A much cheaper but time consuming option....Not that that usually stops you....

On the plus side I don't think you need twin injectors as that engine is so big and multi-cylinder it should be just fine at low rpm.

 

I would not suggest this to anyone but you Mark: Why don't you modify the heads to allow direct injection? All the new high performance cars are using it. If you had direct injection, then the throttles could be located right next to the valves. I would suggest custom-made slides right next to the intake ports that move down. That would, I believe allow you to reap some of the performance benefits discovered by motoman with his little dams in front of the valves.

 

Piece of cake - direct injection easy to do and very cheap lol.

 

But it does improve streetability and tuning.

 

How hard could it be for a wizard like Mark? Drill a hole in the top of each cylinder through the water jacket and into the combustion chamber. Weld in a piece of tubing. Tap the tubing. Voila! Find a few wrecked Audis, snag the special injectors and fuel pumps. You're almost there. Now find a compatible control unit and program it. Bada bing!

Engineering the ultra-trick, close-coupled, down-pull, slide throttles is the rocket science part of my proposal, not the direct injection. The really interesting thing about this setup as I have outlined it is that there is an outside possibility that the greatest power will be generated not, as in every other engine ever made, when the throttles are at 100% open, but at some lesser percentage. That would be ground breaking! But even if not, I bet that it would be a very high performance setup, both powerful and responsive.

 

Perhaps, or perhaps the general and approximate engineering solutions relating flow and power are general and approximate, and do not in fact model optimum configurations. It behooves us to remember that we are not talking about a column of air flowing in one end of a tube, encountering various surface irregularities and flowing out the other end. No, we are talking about a column of air that stops and starts flowing fifty times per second. The exact dynamics of such a situation have not, to my knowledge, ever been modeled. Thus the assumption that we know approximately all there is to know may be overreaching. Motoman does not pretend that he has designed a general solution either. He does not even claim to know exactly why what he has works as well as it does. That it does do so, does I believe lend support to my thesis that the general and approximate solutions could be significantly improved upon. However, short of exactly modeling a reciprocating piston internal combustion engine's fluid dynamics, and then playing with that model on a national lab grade supercomputer, there is not much else one can do to advance except try things that are different.

I'm just saying...

 

Understood - I don't doubt for a second that you will succeed! I have a 1995 Audi S6 on which I am considering attempting an aftermarket direct injection installation some time in the next 5 years. If I ever do it, will let you know how it went.

 

that's an undertaking, the latest V6 audi has the FSI runs very well and makes good power for it's size along with sipping fuel. the advantages of DI, cools the combustion chamber with less fuel. they have it running extremely lean with no load or idling then fatten it up as needed, i can only imaging the ECU programing for that one!

 

I have been playing with this subject for a while myself and I find it facinating. I started out as a lil shaver building small model airplanes and have lightly studied aerodynamics and wind tunnels and things of that nature my whole life. And the two fields, aeronautics and automotive couldnt be more different. In aeronautics so much data is shared its unbelievable. You can run a wing profile in a wind tunnel, and if your numbers are right you will get the same numbers in ANY wind tunnel. But automechanics and flowbenches? Not on your life will these guys discuss anything of great signicance. What your seeing here is just about as much as youll find discussed publicly.

But there are some discussions out there that offer insight. People have suggested low speed turbulence at low test pressures, (10 IWC) that disappear at higher pressures. Some are now even testing at pressures to 200 IWC and port velocities near supersonic.

So I dont really think we need supercomputers or pumping flowbenches, we just need more open discussion.

 

C'est la verité que je ne comprends rien de ce que vous venez de dire. Puis j'ai decidé d'écrire dans une langue que je comprends au moins un peu. Ich kenne auch ein bischen Deutsch, aber nicht so viel als Französisch. Also habe ich etwas auf Deutsch geschriebt um eine Sache zu bestehen.

Glänzende Seite nach oben,
Bill

 

asdfasfd gh dtgr ret aeht asdfgaefgh asdf4 RAFNB RAWGTER YERATSF AFHAG dhshsrhdzgadhxf..........dfg aftgat

 

I agree..totaly, but if you consider that, kjhfergoregnevp, rwlgfj edfihepo oprefjmp 84950,efl;jergper witha bore center of sdghergnrfoe, also the intake tube diameter with,oijhgflergpqrgfm, should be about right..go to it MkE!!