intake adaptors?

[merc-blue]

Has any one had experience with inlet adaptors?
i was talking to a mate about my confussion on what to do with the intake side of my engine, carbies, ITBs, single throttle etc.
and he suggested a ser of 20V quad throttles with a adaptor, apart from raising the powerband (or have i got that backward) due to increased length, is there likly to be major problems?
i have had a look around and seen that some people have used intake adaptors on different bits but im not 100% sure if its worthwhile (it just kills the previous advantage

info on the subject would be handy
Cheers
Rohan

[slide86]

the reason why people are using intake adaptors is cause they have smallport heads and they want to use a bigport manifold or visa versa.

i dont think the performance side of things comes into it that much, its more just to fit the manifold up, rather than searching for power.

[oldcorollas]

and he suggested a ser of 20V quad throttles with a adaptor, apart from raising the powerband (or have i got that backward) due to increased length, is there likly to be major problems?

backwards... but it depends which harmonic you are tuning for, and how bad the original one was.

[merc-blue]

so i wont be losing performance by using one.

[sam-131]

if all is match to the ports why would you loss any power if anything you might gain some

[merc-blue]

i was just thinking becasue the transition is useually done over a short distance with adaptors that maybe it could restict the intake air/fuel flow. obviously i was wrong

[Rodger]

merc-blue,

Depending what engine you plan to use, but there are dual and single throttle body efi set-ups that bolt to any engine that can run or has a sidedraught manifold. This might be your starting point if you want to go efi on a carby engine.

Ie the 2T, Redline make a dual sidedraught manifold.

The 2T-G and 18R-G can have the Solexes swapped for throttle bodies.

Early 4A-Gs have dual sidedraught manifolds available.

As for power band: I understand that it is the total length of the inlet tract, ie from the opening of the ram tube, through the carbie/throttle body and to the inlet valve, that determines the powerband/torque characteristics.

Say if you added an adaptor between the existing manifold and the choice of throttle body and made the total length the same as the original set-up, the powerband would be the same.

Regards

Rodger

[merc-blue]

cheers rodger. im trying to do it in the cheapest way possible, what the plan is ATM 20V Quads onto a 3T the intake manifold will also have to have injectors, gonna take some time to get the length and injector position tuned but with access to the tools, time, skills, knowladge and material its do able IMO. will deffently be more tuneable, reliable and efficent than dual carbies and also cheaper than just getting some thottle bodies (cost from 1K up with out inectors etc

[Rodger]

Ok,

If I were doing this with the 3T. Make the total length as long as possible but still fit between head and brake booster. If you can, gain some length by angeling upwards a couple of degrees to get just above the brake.

I would not go any longer. The 3T has a very nice powerband/torque characteristic with this sort of length.

I assume you are to start with the single downdraught original manifold and are to use the quad 20V bodies and have the manifold from the 4A-G to which the bodies bolted?

Sounds like it will end up as a nice driver.

Regards

Rodger

[merc-blue]

hopefully rodger.
i wont be cutting and shuting i will be making a entierly new manifold bassed on the flanges on the std manifolds

[Rodger]

Well, cool,

That is where I was heading. Using the flanges and adding thick walled alloy pipe between them so there is enough to port.

Cannot wait to see the end product.

Regards

Rodger

[ReQuieM]

Just back on the adaptors, They're used to increase torque. <- Simple answer. The torque is made by increasing the length of the intake manifold, there fore tuning the inake to a lower rpm which in theory moves the powerband (torque, HP) lower, so less top end more bottom end.

V8 boys use these under there carbies to make a cheap 'tunnel ram' style intake. Basicaly because its cheaper then a intake and the V8 intakes (old ones anyway) are pretty short and hug head.

I'd F around with these after your cars set up. If your going a custom intake then aim to set it up for your aimed driving style from the get go and you wont have to deal with em. But if you build it and find it a little sluggish down low then have a play wiht different thickness plates.

Oh and like every ones said, make sure its all matched up! you dont want to add restriction.

On another note anyone know if this screws with the A/F mixing process on an efi setup if placed against the head? It'd make sense to use it before the injector stub but in the case that you couldn't would it have any adverse effect in the whole nice misting?