Vitesse/GT6 MK1 2 Ltr EFI Manifold

[oldtuckunder]

Whilst sat in my PolyTunnel! spending more hours than I should at the weekend fettling new stainless headers to fit before getting coating.  I was using an old Vitesse 1600 inlet manifold as a Jig, as where it mounts to the head it is identical to the MK1 2 ltr one (and in fact the runners are identical bore. Now this manifold is utterly useless in the classic triumph design mode, the flow within it must be horrible! it was originally fitted with 2 x downdraft 1.25 Solex carbs, and just about everyone junked them and the manifold as soon as the 2ltr manifold was developed. Why do I have one? Well you never know when something might be useful!

However whilst looking at it I realised that if I ever want to go EFI that the three inlet tracks were an ideal ready made base, i.e. to fit EFi I would have to make something almost identical.

And then whilst pondering and thinking about the dual throttle variable length inlet tract system on the Cosworth, I thought hang on could I use this manifold to create something similar. The objective seems to be to create the most turbulent flow you can at light throttle openings (and I can't imagine anything more turbulent than that manifold) and then open up a direct short high flowing passage at higher throttle openings.

So could I piggy back a dual throttle body on a dual Plenum, a top smaller one feeding via the convoluted existing carb mounts, and a larger lower one feeding direct into the back of the manifold at the end of the three paired runners?

Have a look at the pictures and let me know what you think. Its something I may never get around to as EFI is banned (unless originally fitted TR8!) from both RoadGoing and Modified and there is no way the Vitesse is ever going up to Race. Interestingly mechanical fuel injection isn't banned from modified (so room for thought!)  But at worst at some time in the future if someone is thinking EFI on a MK1 head it may give them some ideas.

Alan

 

[Nick Jones]

I'd forgotten what a gruesome object that inlet is.........  Though I've met people who claim that their Solex equipped Vit 1600 went very well and was good on fuel....... I always wonder what they were comparing it to.  Standard Herald 1200 or Austin A30 maybe!

Not sure the above sketch really achieves the variable length objective and the need for turbulence in manifolds is, I think, more relevant with carbs when you are trying to keep the fuel in suspension.  I've been pretty happy with my much simpler design so my vote would be to lop the runners off, add injector pockets, bell-mouths and a simple plenum and throttle body.

Chris Witor had an injection manifold made for the Mk1 engine years ago.  A thing of beauty (and expense) in TIG welded aluminium with long, tapered machined  runners.  I think there was a pic on his old website but can't see it now.  I have seen it in the flesh, years ago, even before I'd made mine but AFAIK it's never been used.  I did show him my wonderfully crude Mk2 version in action a couple of years later and he managed to be polite about it.

 

Nick