The V8 Owners Forum -

Has anyone ever drilled out the flapper intake manifold and fitted hotwire injectors? looks feasable, only 2mm difference. The twin plenum intake runners are 41mm where as the hotwire is only 38mm or do i just bite the bullet and send v8 devs my setup and have them port to 45mm?

More easy just to change low inpedance injectors for high impedance ones.

thats what im doin but they are hotwire style and dont fit flapper, hence the question 2 drill manifold

IIRC i fitted normal (hotwire) injectors in a flapper manifold with no mods, they just pushed straight in!

I did just that, fit o-ring type injectors in my old flapper mainfold and it did work although I was never convinced the lower o-ring sealed perfectly. Obviously you will need the hotwire fuel rail as well.

It seemed to run ok with no obvious signs of leaking but when supercharged it I had a feeling when on boost it was leaking out the lower seal although I could never actually prove this!

Tom.

If it was leaking on boost it would be fairly easy. Some petrol would be escaping past.

o-rings are very simple. If they are a good snug fit and not damaged, it's pretty difficult for them not to seal. And all typical Bosch style injectors need is a smooth round bore on order to seal. So if they look like they seal, chances are they do.

Just make sure the injectors cannot move up/down so the o-ring doesnt seal anymore.

As for porting...isnt there anywhere on Oz that can do it ?

Stevie, i could get the porting done here, but getting larger trumpets would be the hard part. I guess allready having 3mm larger intakes is beneficial, how much more am i going to benefit by going another 4mm on top of that is the question. Car only weighs like 800kg so would the gains be noticable, i will have to speak to V8 devs.

Whether or not the larger intake valves are better is debatable. That would depend on head porting as well.

A good thread about head work, worth a read.

http://www.pistonheads.com/gassing/topi ... ve+jobs%3F

A move to an ITB style setup would probably be of more benefit, as you'd be getting a straighter shot into the ports and removing the 90deg bend on the original intake.
If of course it can be achieved on a budget

Being tvr heads they are pretty much ported to the limit allready, the intake manifold size is 44mm on a standard 5.0ltr tvr intake, so i know my twin plenum manifold could be ported out further, its whether the the cost of it will be worth it on such a light car, like i said i will contact them. cheers

That's my point though. Bigger isnt always better...at least when it comes to port sizes.
Potential top end gains vs low-lid losses are probably not worth it.