MG Midget Madness (i.e. It was either this or kill it with fire)

[GySgtFrank]

Had a question on it so I'll post this a little early.

I'm going stir crazy waiting for more pipe from RB, so I started figuring out the other big bug-a-boo with this swap. Cooling.

Since the rotary requires far more cooling than the original piston engine, and frontal area is so limited, I had to plan out some rather strange stuff. The FC radiator is a single pass unit with 374 square inches of frontal area. The oil cooler carries about 30% of the engine cooling and is about 91.5 square inches of frontal area. The original MG radiator has only 140 square inches of frontal area and no oil cooler standard. Obviously we have a problem Houston. The tiny opening was going to need some rethinking to get a lot bigger radiator in there, not to mention what to do about an oil cooler.

Here's a picture of the original opening after I had made some cuts to open it up a little. The Diet Coke box was supposed to only be background so you could see the opening better. Didn't work so well, but you get what you pay for.


radiator opening 1 by Kevin Frank, on Flickr


I'm going to open it up to the full width of the car. Removing the front stubs of the upper frame rails so I can fit the side tanks all the way up against the sides and maximize my radiator size with a 14" x 28" double pass radiator. I'm still down a little on frontal area from the FC radiator at only about 336 square inches, but I hope the extra efficiency of the double pass unit will make up the difference. Unfortunately it is going to have to be custom made so it's going to be expensive.

The oil cooler I plan to use is an 11"x11" square stacked plate cooler that I will set underneath the radiator and between the frame rails. It is actually about 30 square inches larger in surface are than the original. However because I plan to mount it flat, (not much choice as there is just no room anywhere else), it will have less than great air flow. I plan to run a shallow scoop under the car to gather air for the oil cooler and run the fan shroud over the cooler along with the fan so that it draws air through both.

A picture of the radiator opening, partially opened.


radiator opening 2 by Kevin Frank, on Flickr

I have to finish opening it up on the top pieces and cut down the frame rails.

[FC Zach]

Liking the built and the opinion pictorial from your Flickr account

[chibikougan]

There is also the option of upping the coolant flow rate also Gunny and or pusher and puller fans.

[GySgtFrank]

Originally Posted by chibikougan

There is also the option of upping the coolant flow rate also Gunny and or pusher and puller fans.

I'll be using a puller electric fan, either a single 14" or a double 12". I'm not quite sure yet which way I'll go. A pusher fan tends to block incoming air so not such a good choice for steady state driving, but if I get desperate it may come to that. Upping the coolant flow may or may not work, too fast and you're not transferring enough heat as the coolant cycles, too slow and you are losing the opportunity to shed more heat. Again if it's a problem I may have to play around with that. I think I'm going to be alright though as I should be relatively close to the stock FC specs. I'll have to see once it's up and running.

[chibikougan]

Originally Posted by GySgtFrank

I'll be using a puller electric fan, either a single 14" or a double 12". I'm not quite sure yet which way I'll go. A pusher fan tends to block incoming air so not such a good choice for steady state driving, but if I get desperate it may come to that. Upping the coolant flow may or may not work, too fast and you're not transferring enough heat as the coolant cycles, too slow and you are losing the opportunity to shed more heat. Again if it's a problem I may have to play around with that. I think I'm going to be alright though as I should be relatively close to the stock FC specs. I'll have to see once it's up and running.

Yeah you seem to be close enough to spec so I would think a half puller on each for emergency use will be fine. That way you get the best of both free air and forced air when needed.

I see a lot of non clutch fan converted to E-Fan race cars and they all run the fans to the oil cooler. If temp gets around 180 while idling kick on the fan and the temp just drops.

[GySgtFrank]

Originally Posted by FC Zach

Liking the built and the opinion pictorial from your Flickr account

Thanks Zach. I'm trying to make the thread as useful and entertaining as I can for anyone else stupid enough to do one of these conversions. There is nothing unique in what I'm doing, it has all been done before (except maybe the EFI if that works out). The problem I had is that the build threads I read through left a lot to be desired. I especially want to show and discuss all the pitfalls and problems involved, including my own screw ups. I'm not too proud to admit that sometimes I'm not half as smart as I think I am. Showing (or at least admitting to) the failures is almost more important than the successes for learning. I see far too many people with their egos on the line in these things and will only show you what went right, or disappear all together when shit doesn't work. The bad part is that it leaves somebody reading it later with the impression that the project/mod was a success and they try it themselves.

edit: I used the opinion picture on EJ the other day. I have to keep an eye out and collect these little tid bits so I can defend myself 'round this place.

[t_g_farrell]

Originally Posted by GySgtFrank

Thanks Zach. I'm trying to make the thread as useful and entertaining as I can for anyone else stupid enough to do one of these conversions. There is nothing unique in what I'm doing, it has all been done before (except maybe the EFI if that works out). The problem I had is that the build threads I read through left a lot to be desired. I especially want to show and discuss all the pitfalls and problems involved, including my own screw ups. I'm not too proud to admit that sometimes I'm not half as smart as I think I am. Showing (or at least admitting to) the failures is almost more important than the successes for learning. I see far too many people with their egos on the line in these things and will only show you what went right, or disappear all together when shit doesn't work. The bad part is that it leaves somebody reading it later with the impression that the project/mod was a success and they try it themselves.

edit: I used the opinion picture on EJ the other day. I have to keep an eye out and collect these little tid bits so I can defend myself 'round this place.

+1 on this. It helps to see the good, bad, and the ugly on projects like this.
I always thought this would be a neat swap but after seeing the amount of
fabbing needed I certainly wouldn't try it. Thanks Gunny for sharing.

[GySgtFrank]

Originally Posted by RETed

Check out AFCO Racing?
You should be able to find one close, and it shouldn't cost more than $300...?

-Ted

I checked them and a lot of others. 14" H cores are non standard. I can get something at 15.5" H, but there is no way I can make it fit unfortunately.

Originally Posted by t_g_farrell

+1 on this. It helps to see the good, bad, and the ugly on projects like this.
I always thought this would be a neat swap but after seeing the amount of
fabbing needed I certainly wouldn't try it. Thanks Gunny for sharing.

Glad it helps. I have done more fabricating than what most would probably consider really necessary, but I'm picky on how I want it to fit. There is a fair amount of fabrication involved with this swap no matter how you go about it though.

[Pete_89T2]

This is an out-of-the-box thought, but have you considered relocating the radiator and/or oil cooler out back? That would present a bunch of other problems, like proper airflow and plumbing/packaging, but it might give you more space to work with and solve the capacity/radiator size issue.

You don't need no steen-king trunk space, right?

[GySgtFrank]

Originally Posted by Pete_89T2

This is an out-of-the-box thought, but have you considered relocating the radiator and/or oil cooler out back? That would present a bunch of other problems, like proper airflow and plumbing/packaging, but it might give you more space to work with and solve the capacity/radiator size issue.

You don't need no steen-king trunk space, right?

I have almost no steen-king trunk space to play with Pete and even less room to duct air to it. This car is tiny. I had forgotten just how small they were until I bought the damn thing. It is about 10 1/2 feet long without the bumpers, 48 1/4" tall, and only 4'5" wide. I'm already going to have to cut into my trunk space (or should I say "the rear glove box"?) later in order to expand my fuel tank a bit when I modify it for an in tank pump and cup for the fuel injection. The original fuel tank is only a 7 gallon tank which may be a bit less than optimal with a rotary.

[RETed]

Originally Posted by GySgtFrank

I checked them and a lot of others. 14" H cores are non standard. I can get something at 15.5" H, but there is no way I can make it fit unfortunately.

It looks like they have a lot of 27.5" / 28" by 19" stuff...
Can't you just cut the core down and redo the endtanks for your application?
Can't be more than $100 in labor and welding locally?


-Ted

[GySgtFrank]

Originally Posted by RETed

It looks like they have a lot of 27.5" / 28" by 19" stuff...
Can't you just cut the core down and redo the endtanks for your application?
Can't be more than $100 in labor and welding locally?


-Ted

The one local place, that I would trust with something like that, won't do that kind of work on aluminum radiators. They must have gotten burned on it at one time or another for them to be that gun shy of it. I don't have the means to weld aluminum myself. I really need to do something about that lack one of these days.

[RETed]

Originally Posted by GySgtFrank

Unfortunately it is going to have to be custom made so it's going to be expensive.

Check out AFCO Racing?
You should be able to find one close, and it shouldn't cost more than $300...?


-Ted