Old FM mani and ew fitment issue
 

I few months back, I bought a used turbo kit. I have what I believe is an old FM manifold, and an ebay down pipe. The dump tube from the Tial waste gate and the downpipe are trying to occupy the same space.

I thought about bending the dump tube further down, but that will hit the motor mount. I then tried turning the wastegate to face towards the front of the motor, but then the wastegate flange hits one of the water lines for the turbo.

The "kit" came with this downpipe, but I don't think it was ever used. It still looks new.

Should I buy a new downpipe? Or Should I just run and internal wastegate? The turbo is a 2560, and I would like to upgrade to a 2860 down the road.

I would appreciate any advice.

https://www.miataturbo.net/attachmen...ine=1377058341
https://www.miataturbo.net/attachmen...ine=1377058341

Is the internal gate not welded closed? Also machine all the flanges flat and ditch the gaskets or it will leak. Shift the coolant lines if needed.

It's pretty much guaranteed to leak anyway -- that looks like an old FM3 manifold and they were notorious for it.

--Ian

The internal gate is not welded shut. I planned on making a bracket to keep it closed. I think that welding it shut would make it harder to sell later on when I upgrade to a T28.

I tried turning the water line 180 degrees to face up. The line hits the studs on the turbo side of the manifold. Is there a way to use hard lines(smaller diameter than soft lines), at least until I get past the turbo.

buy a FM or BEGi DP; you'll still to need to custom fab the ewg back in. or run the dump. or ditch it, block it off, and run iwg.

Thanks for the replies. I think I will just end up buying flanges and have an attempt at making a custom downpipe. I'm looking at Begi for the flanges.

Search the first few pages of my build thread (in sig). I ran the FM3 for years and I constantly had issues with making things work.

I had space issues with my 2-1/4" downpipe and the wastegate dump pipe occupying the same space. You're running into that issue right now. That's actually the reason I sold it. I went to a larger turbo and the choked downpipe made spool up too slow to justify the power it made. Then I was forced to decide if spending money on antique turbo hardware was worth it (for me).

You could flip the wastegate and dump the pipe towards the front, use a smaller downpipe or use a block-off plate and run the turbo's internal wastegate (perfectly fine for a stock block car). You can easily blow a stock block using that manifold.

Good luck.

Thanks for the input. I'll start going through your build thread now.

The motor currently has Supertech pistons, Carrillo rods, and ARP head studs. The main reason I want to use the external waste gate, is that I would like to run higher boost. I also have RX7 550cc injectors, 190 fuel pump and a diy megasquirt on hand.

https://www.miataturbo.net/attachmen...ine=1377235756
https://www.miataturbo.net/attachmen...ine=1377235756
https://www.miataturbo.net/attachmen...ine=1377235756

Higher than what?

My motor is similar (Carrillo A beams, 9:1 Supertechs, 99 head P&P, 2560, RC 550 cc/min injectors, Hydra 2.5, current FM2 manifold & DP) and the only downside to running the internal WG is that mechanical boost creeps to around 10 psi by redline. Since I'm running 15 psi EBC, I don't really care about that, and if I did I'd port the internal WG, not go EWG.

That 15 psi is good for 270 rwhp on a Dynapack, and turning the boost up does very little for the power (18 psi adds maybe 8 hp, but a lot of heat), so I'm up at the efficiency limits on the 2560.

That FM3 manifold is a nightmare, everyone I know who's had one has constantly battled leaks and backing out studs/nuts from the 2-bolt flanges for the EWG. To make matters worse, the access to those flanges is very limited, so you've gotta take a bunch of stuff off just to get to them to retighten the nuts. There's no benefit to the FM3 EWG setup here, IMHO, only drawbacks.

--Ian

Hm, my plans were to go about 15psi on this turbo and 18 psi on a gt28. Should I upgrade studs before I swap motors? Also, how much power do you think the 99 head adds?