225 promax with one piece adapter plate

[ChrisCarsonMarine]

Massaged from 1/4 aluminum plate,one Ss bolt,and a little Marine Tex.I expect this is similar to Steve's setup,Chris

[bigboy]

Thanks Chris!

Should be ok to drop a stock 2.5 200 on a stock 2.4BP plate with this modification?
I might do it in epoxy or does it get too hot?

[ChrisCarsonMarine]

You could use epoxy,not any heat to speak of.Probably easier to at least rough it in with aluminum so who will have a durable gasket surface,and won't have to make forms...

[bigboy]

Ok Will prob just have it welded.

Any experience with the BP adapter on 2.5 200

[Go Time]

Well I started my one piece adapter project as well
I'm modifying a an oval port 280 plate. Going to weld in bulkheads to build poppet discharge chamber and weld up the two drain holes and then drill small drains to drain the discharge plenum. These are the before modification pictures. Will post finished product when complete.
Then replace 280 tuner with a Promax oval tuner.

[Greg G]

Well I started my one piece adapter project as well. I'm modifying an oval port 280 plate. Going to weld in bulkheads to build a poppet discharge chamber, and weld up the two drain holes and then drill small drains to drain the discharge plenum. These are the before modification pictures. Will post finished product when complete. Then replace 280 tuner with a Promax oval tuner.

This will be interesting to watch. Thanks.

Will the 1 piece 280ROS adapter, once you modify it to use poppet and 120 thermostat cooling, be run on a Promax 225 20" or the later PCM555 controlled "X" model?

[Go Time]

It will be running a new Promax (not an X, sorry Greg, not a fan of the X). By new I mean new block with all new internals except crank & rods. Many other new parts. It will also have an SVS and a Brucato ACU with a curve developed specific to the application (dyno tuned).
It will be on a 15" smoothback mid, with a JC coned touquemaster.

[90 5.0]

Well I started my one piece adapter project as well
I'm modifying a an oval port 280 plate. Going to weld in bulkheads to build poppet discharge chamber and weld up the two drain holes and then drill small drains to drain the discharge plenum. These are the before modification pictures. Will post finished product when complete.
Then replace 280 tuner with a Promax oval tuner.

There are so many tuners I always forget what's what.
The oval promax tuner, that only came on a 15" with one piece plate right?
Do you expect it to perform better down low than the 280 tuner?

I guess what I'm asking is what are you trying to accomplish running a promax tuner on a 280 one piece plate?

ive never ran a real promax oval tuner my factory 15" promax had a 2 peice plate and a tuner that is a short rectangular one.

The tuners I have available to me are 280, 2.4 200 bell, Bridgeport , promax , and some stock long 200's.

Thinking of trying the Bridgeport tuner next.

[Greg G]

There are so many tuners I always forget what's what. I've never ran a real promax oval tuner. My factory 15" promax had a 2 peice plate and a tuner that is a short rectangular one.

A true factory tuner that came only with the 15" Promax is a very rare bird. Do you happen to have a picture of that?

[90 5.0]

A true factory tuner that came only with the 15" Promax is a very rare bird. Do you happen to have a picture of that?

I'm not sure if I do or not it's in the mid right now.

I'm about to pull the 2 piece plate and put a Bridgport one peice on that can and hang the 15" on the drag and put the promax back on the bullet but new to fix my 280 15" mid first so hopefully in a week or so I'll have that mid pulled down and can take some pics.

It looks very similar to a Bridgeport tuner though. I'll put them next to each other and see what the differences are.

[bigboy]

There is another way to use a popet and thermostat on a one piece plate. If you are using a lightweight or performance cowl pan, weld plugs in 4 of the base plate holes, the ones that let water out of the powerhead and into the exhaust plate. This way the water has to pass through the poppet in the block. You do not need to modify anything else.

Steve,

I think this is How they did It with the 200xs.

Can You conform this?

Thanks

[tux974]

225SS Promax's tuner that came with the 1pc plate on the 15" mids is the one on the right of Go Time pictures. The
one on the left is a stock 280, both are oval.
Here are a couple below that are on my motors. The side by side on the bottom is a comparison with a 245/260 early tuner.

[Go Time]

Tony is correct. Post 65 has a picture side by side of the 280 tuner and oval Promax SS tuner. I believe the Promax oval tuner is probably the best tuner for the powerhead I will be using. Since the only one piece adapter I had was from my 280 I needed to match the oval ports so I am using the SS tuner. I tried a 280 tuner on another Promax and it was a little lazy.

[90 5.0]

The one that came on my 15" 2 piece plate motor looks like the 245/260 one you have pictured.

I I do not have a 260 tuner to put next to t to compare only an oval 280 or the Bridgeport tuner which looks similar also.

Need to set them side by side to tell what all the difernces are.

I'm gonna run the one peice Bridgeport a bit to see if it gains some high end but doesn't lose much bottom.

Two piece plate only turns 8500ish but is strong down low, a 280 plate turned 9400 but was weak on the bottom.

[tux974]

First pictures is a 225PM SS tuner next to an early 245/260.
The second picture is a late 245/260.
Third picture is the early 245/260
The biggest or only improvement between the early, late was the mounting flange and casting.
If you look closely to the last 2 pics you can see the flange thickness and mounting foot print. Not much or very little if any performance wise.

Mark, is correct!
With the 280 tuner you will be weak down low but it should allow you to spin higher if that is what you are looking for.
The SS tuner for a 225PM is a great match hence the reason Mercury developed it.
I have an SS PM tuner identical copy made of stainless that I plan to have copied for future projects. Will get a picture of it up today.