Port matching my smallport -> bigport 4AGE manifold adapter

[Golberg]

Well I just bought a T3 big port to small port manifold adapter to run on my small port 4AGE motor. The point is to be able to my big port RWD manifold on my small port since they never made small port RWD manifolds.

I wasn't all that impressed though with the adapter because the ports aren't even close to being the right size...

Here is a photo so you can see what I'm talking about:


Now I've vaguely researched port matching manifolds before and I get the general idea. I've never bothered before though because I've trusted that the factory manifolds would be close enough as they are.

as you can see though from the photos, there is a huge (2-3mm) step along the bottom of the manifold adapter (and no its not because its hanging down on the top studs in fact its pushed all the way to the top in that photo). I can't imagine that the step is the best thing for airflow so I think I may need to do some port matching?

The thing is, as far as I can see the only way would be to grind large amounts out of the intake ports. I don't really like the idea of doing that though as there is no chance a factory manifold could ever be used again as far as I can see.

The other thing I'd be worried about is that I will not be taking the engine apart which means all manner of filings would quite possibly end up inside the motor.

So what would people recommend?

I thought maybe fill the ports on the adapter up more with epoxy then shape to suit, would that be a possible idea?

[thechuckster]

does T3 want to take it back and replace it with one that matches the head?

How does the adaptor face compare with a factory gasket?

Epoxy would do the trick (Race Magazine had an article a while ago about using epoxy in porting heads)

[oldeskewltoy]

Are the alignment dowels(head to TVIS normally) being used???

Or... you could mod a fwd intake manifold........ FAR better than that adapter!

Here is a step by step process....
http://hachiroku.net/forums/showthread.php?t=12315

[jono]

Just get the smallport manifold done. it cost me $200 at Thornleigh Cylinder Head Reconditioners.

Alternatively, my mate has a smallport inlet manifold which has been converted to RWD for sale.

[Cuzzo]

Im pretty sure the standard inlet manifold isnt exactly port matched either. Theres still a small step however i dont think its 3mm!!

[Sam_Q]

how well does the top match up?

[Golberg]

oldeskewltoy:
I haven't managed to source all the bolts and studs to suit a big port yet, but its currently sitting on the standard small port studs whilst pushed all the way to the top.

Sam_Q:
The top is pretty close, although the ports sit a a fraction too high for it, I'd need to grind off less than about 1mm to make it line up.

For everybody else, I already have a cut-n-shut manifold. I bought this adapter plate though because I got a RWD manifold for $50 and wanted to run it. And the reason I want to run the RWD manifold is because unlike most AE71's and KE70's mine isn't actually a shitbox and it seemed like a good opportunity to make my engine bay neater.

In all honesty I wish I had started with a big port motor, would have saved many headaches, but I've got the smallport and its all wired so I don't want to change now.

I think I'll try emailing T3 and see what they have to say.

Is the general consensus that they really could have done a lot better a job of making the thing?

Thanks for those who have replied.

[thechuckster]

fwiw, the stock 3sgte head-tvis- intake joins also have steps - but around 2mm, easily fixed with a die-grinder if you feel brave and the head doesn't need any work as the steps go the other way.

[Golberg]

Just got word back from T3:

Yes, that doesn't seem right. Either the studs are bent on the head, or maybe our adapter shifted during the machining process. If you can, can you please check our adapter against the stock gasket, as that will tell you if it was machined improperly. We've never had a problem before with fitment, but something could have gotten goofed up!

I've sent them the photo away with the gasket behind it showing the same thing, so hopefully I wont need to bother tying to sort this one out.

[Ben Wilson]

Air is a funny thing, a step like that will make very little difference to flow, a step the other way, like on the back of a stock T-VIS system will hurt a lot more.