Fins on back of Valve & Fins pre TB

[immortality]

I'd be sceptical unless those numbers were from an independent test. Walker also did a Twin TB for the 304's claiming good numbers but it was a bit of a dog in reality. Certainly no real gains on a standard-ish type engine.

[HQ355]

Has anyone had a go at modifying the bunch of bananas and if so had any success ? I have a spare one and all the equipment at my disposal to do so. I really can't see why intakes for the holden V8 are so expensive and would love to get somthing that breathes better and dosnt get the heatsoak of the bananas as well ?

[immortality]

There are a number of modified banana's type manifolds about. Most have the top machined off between the flanges on the runners and remove the standard plenum, then they weld in a new plenum and TB's. The most successful is probably the Trickshift one.



I can't find any pics of the Walker one, but it was just a large sheet metal plenum with 2 standard Holden 65mm TB's on the front.

[HQ355]

Yeah I havnt heard much good about them and even according to themselves they need more work for a stroker motor (which
mine is) and they start at $2500ish just for a compromised cut and shut bannana manifold ! I wish someone would just
Tool up and copy the group a twin throttle manifold, they can't be that expensive to make ?

[immortality]

Damn right, the original Grp A manifold is still one of the best EFI manifolds for the Holden motor.

Someone did make a copy of it but it wasn't cheap. Flowcraft I think it was.

[vlad01]

we did a slightly over 4L plenum on a turbo car real soggy down low mad up top had 90mm throttlebody too you could run it N/A and rev it full throttle and look in through the TB at the ends of the runners and see fuel domed at the end of the runners like half tennis balls was pretty cool LOL youde really have to mod the runners to suit the plenum to tune it as a package.

yeah that fuel mist floating above the runner is reversion. Runners are not optimal in length, often too short for the intake wavelength. Thats a power killer when that happens.

but depends on the rpm target you are trying to tune for I guess.

[vlad01]

drop in runner to make them longer again

we have been working on this idea for our workshop VT V6 racecar, machine receivers into the base of the manifold and have knock in trumpets to alter runner length, could be used to tune for different driving events, etc...

If you want a test dummy, I am it...

LOL, I proposed almost this exact idea to a manufacturer/supplier many years ago, however it wasn't something on there radar as they were working on other (model) engine developments. Although they did believe in the merits of the proposal they weren't going to pursue it and suggested I manufacture something myself. Unfortunately I don't have access no enough equipment to manufacture it.

However, if you look at the old Grp A twin TB manifold you would see exactly that, a base with trumpets inserted into it and even today I believe that 888 racing change the intake trumpets on there engines to suit different tracks so there must be merit in the design aspect.

I was there with Biggvl talking about this idea, I had it in my head before talking to anyone about it. I got the idea after seeing some of the good EFI manifolds for v8s in the states.

[vlad01]

Yeh i had seen testing with the mace lid spacers before and made it worse, but yeh you would have to alter runner length and size to match the plenum to gain out of it. Boost would be a different story, I know larger runners help volume and smaller aid's flow rate, shorter helps high rpm and longer low rpm, the mace plenum spacers do help N/A Torque in lower rpm by making them slightly longer, so a next thought could be to a drop in runner to make them longer again and would having the end fluted flat or at an angle be best? flat would prob be best for air distribution? If you made them say half way up the plenum and added lid spacer on not that i have one.

its closely linked to the cam as well.

[vlad01]

i think i remember reading about that walker one, bolt on stock engine got 20rwkw gain, something like that. Im guessing the torque on the bottom end would be better with smaller tubes and longer runs

shit, that's pretty good gain if that's correct.

[Jayme]

A mate of mine has a set of cut bananas, bought at a swap meet, havent used them yet, but they have the top cut out between the 2 flanges and a big box welded on with 2 throttles at the front of it. the shape isnt too far different from the come racing twin throttle manifold. TTVN told me his car ran this cut nana design and it wasnt too far different on his twin turbo car when he went to the come racing manifold, so they cant be too bad. ive seen people whinging about runner length being too short on the cut nana design, and they are right, it may not be ideal, but in reality the runners are about the same length as a come racing manifold and on a big boosted engine they still flow a fuckton more air than the stock nanas.....