tech collaboration: 20V throttles

[Toycrash]

Throat diameter @ trumpet: 46mm
Throat diameter @ manifold: 44mm
Throttle diameter: ~44mm

I measured 43mm throttle on late silvertop and 45mm on blacktop throttles.

I'm going to fit the 45mm quads in silvertop head, and done some measuring, alltho its not that simpple...

Blacktop intake is way different (port shape) than silvertop one.

So what i'm going to do is, use blackie throttles and port silvertop intake to suit them.
In here comes another problem... Silvertop tb is a round and blackie tb starts to change shape IN the tb. So i have to port the intake to suite this shape..
Unless i decide to weld bt intake and port it then to match silver head.

Allready done some cutting to remove unwanted crank case ventilation chamber.
Some pics for reference.

[Steve M]

Tricky,

How well do the silvertop throttles line up with the standard 18RG intake stud pattern in the head.
I realise that the pattern is different from left throat to right throat of each pair, but how closely do cylinders 4 and 2 line up?

I reckon they should be pretty close, but I'd like to know for sure.

[TA-022]

isnt it just make a think plate (10-15mm) to bolt to head then tap out side face in same pattern as quad plate thingo???

no going into flow paths and all that but to make em fit isnt that the basics to it???

asking not stating here, this has me intrigued.

[tricky]

Tricky,

How well do the silvertop throttles line up with the standard 18RG intake stud pattern in the head.
I realise that the pattern is different from left throat to right throat of each pair, but how closely do cylinders 4 and 2 line up?

I reckon they should be pretty close, but I'd like to know for sure.

Painfully close from memory. An adapter plate is all well and good, but injector bosses still need to be epoxied/welded/threaded into the manifold. I'm sick of having the throttles lying around, and I want more midd range torque, so hopefully I can do this pretty soon.

[Ben Wilson]

Tricky,

How well do the silvertop throttles line up with the standard 18RG intake stud pattern in the head.
I realise that the pattern is different from left throat to right throat of each pair, but how closely do cylinders 4 and 2 line up?

I reckon they should be pretty close, but I'd like to know for sure.

PITA close, here is a pic of some adapters I made up to hook silvertop TBs to a dual sidedraft manifold.



I had to redrill and tap one of the holes in the manifold because it was so close to the lower hole in the TB.

[TA-022]

why not mount the 20v plate the quads came of direct to the block via and adapter???

btw this isnt me saying this is how you should...its more of a pro and caon of doing it question.

thanks

[takai]

Cost mainly, mine is bolted straight to the engine with a single billet alloy manifold. But when Ben was designing that they didnt have those in production, wheras the Redline DCOE manifolds are numerous and relatively cheap. The adaptors would be simple to make and effective. Infact this was one of the ways i considered doing mine.

[TA-022]

how would you mount ya injectors though if you went the way of redline?

[takai]

The injector bosses for a 4AGE are moulded into the head. No need for anything on the manifold anyway.

[TA-022]

psss that doesnt help me! lol

how hard would it be to have injector bosses welded to a dcoe manifold???

shops around that could do this easy enough?

[takai]

It woudl be reasonably easy. I cant remember the material which the DCOE manifold is made of. Im pretty sure it is alloy of some sort. You can easily get injector bosses in various metals, and most competent alloy fabricators could weld it up for you.

The injector rail is similarly easy.

[Ben Wilson]

The redline manifolds are high magnesium (I think) content aluminium which makes them a PITA to weld to. Then you've got allignment issues to deal with, then custom fuel rails. Personally, I'd either go to EFI hardware throttle bodies, or some bike ones. I've got some nice 42mm GSX-R 750 TBs at home just waiting for a project one day....

[tricky]

Does anyone know anything about epoxied injector bosses? A few major companies sell them, but are they road legal? Epoxy is pretty resilient, but it could still be an engineering issue. Just thinking of it as a budget alternative for those trying to adapt a DCOE manifold. I wouldn't wanna weld the stuff, and I'm sure a lot of shops would turn their noses up at the proposition too.

[Ben Wilson]

If you get the right epoxy you should be right. Check the temperature rating of the epoxy closely as a failure could get nasty. If you painted the manifold it would be hard to tell they were epoxied though.

[oldcorollas]

bringing this up again...
and will have pictures soon..

weight of bare TB's plus linkages and trumpets = just under 3kg.
manifold and tubes and injectors, fuel rail and crap (everything between bare throttles and head = 3kg.