Adapter Plate Tech

Adapter Plates
When using the HF/STD/CX manifolds, you will need to build an adapter plate to mate the manifold and turbo together. Before you send me an email and ask If I sell them, I do not, I will show you images of ones we have done, to get you an idea of how to do it. First you will need to get the HF/STD/CX manifold gasket and the turbo inlet gasket. Determine what size of steel you will want to use, and lay it out.


This is a 14b/T25 DSM Plate that we have done, The plate is 3/4 thick and is 4.5 by 4.5 long. You first center the gaskets on the plate and mark everything. Be sure that bolt holes do not overlap. How do you cut a hole that big? Well if you know someone who has a drill press, you can use a metal hole saw, but you have to turn the RPM's down on the machine (very low) in order to to make a cut, otherwise it will just grind off the teeth of the bit. On some of our first plates we chucked the plates up on a lathe and cut the holes out, but that was a big pain in the ass. If you know anyone who has a mill, they can also do this.

The inlet of the plate (manifold side) will need to be port matched, you can do this with a high speed die grinder and carbide steel bit.

Work all the way around the plate, until you get a smooth chamfered edge. This makes the transition from the manifold to the turbo nice and smooth.

Once the edges are smoothed out, you can then tap out your holes for mounting the plate to the manifold. I like using Nissan Pathfinder studs. I use 10x1.25 thread pitch on top and bottom of the plate.

Ok, this is really the only flaw, and bitch part about using these style plates with this turbocharger. The exhaust housing already has threads in it, so you have to drill them out, so you can put a bolt from the bottom side up into the plate.

Here is a shot of a few plates we have done, Left to Right. The first plate is a T3 plate. Second is our prototype DSM T25/14B that will allow you to use countersunk bolts instead of drilling out the threads in the housing. The last plate is the very common plate we use on most of our setups.

This is another T-3 Plate that we did, this was a bit odd, since we used a blow torch to blow out the large hole in the middle, then cleaned it up with a die grinder.

Shots of our first plate we ever did, as you can see we notched a small section out for the dipstick tube, you really dont need to do this, you can bend the tube back with a prybar.

Another T-25 Plate

On Td05h's (14b's) and TD04's you can see how you can only use 3/4 bolt holes, so we put a fatty weld around the plate and turbo for reinforcement.

I always recommend using the factory gaskets on both sides of the plate, so you will get no leaks. You can get these at the dealer.

This plate was used in Mike's D16z6 IHI Turbo Project (tri-flange subaru)

This plate was used in Steve's DX IHI Turbo Project (4-bolt IHI flange)

This is DropShops early adapter plates, They were angled that would allow the use of stock DSM O2 housings, it would clear the front cross member.

Gary & Randy's Adapter Plates, they were for sale at one time, but I dont think they are anymore...? check out his site for more info

The O2 Housing Flange for DSM T25/14b/Td04, if you want to make a trick downpipe order one of these from Roadrace, and build yourself a nice downpipe and o2 housing.

This is why we dont use aluminum adapter plates, just incase you ever ran into a lean condition, the egt's would get pretty hot and easily melt the aluminum.

Adapter Plates