I'm almost positive I'll be using the Microtech EMS. I'm not 100% sure on that though.

Very nice numbers, i am now subscribed to this thread :)

anyway, a few quesitions:

-Can you post up some more info of your guru box coming in? I'm not familiar with it...
-Can you post some more pics of your subframe? I am still wondering how you mounted the engine to avoid all bumpsteer issues
-What size ports are you running on the engine?
-What are you running for throttle body and intake manifold? stock 20b parts? are they ported?

Thanks, and good work, the car sounds great!

I can answer those questions for you. In Mike's case, his engine was built using the 13b-rew rear plate. This is what allows him to re-use the Fd subframe which allows him to re-use the Fd engine mounts however, a new oil pan will need to be fabed to fit within the Fd subframe. Also, the LIM will need to be shortened to allow for enough hood clearence. Thats why his car has no bump steer problems.

So does the extra length of the rotor just "hang over" the steering rack?

I've been thinking about a 20b for a LONG time, but I've been waiting to see how other people do things so that when I do mine, it will be easier :)

How much does the LIM get shortened? Is a new flange welded on or is it just cut down a few mm?

Thanks, Brian

yea, does that effect anything? I'd wonder if there are any ill-effects to mounting the engine that way? that's something i'm not familiar with, but it sounds fantastic!

what kind of mods to the rest of the engine does it take to use the rear plate from the 13b?

and like Wargasm mentioned, whats the process for getting the LIM shortened?

And are all the oil pans like that a custom job? or is there some rotary company that produces them?

Sounds like this is the way to go when going 20B. the custom subframe/bumpsteer issue has always worried me.

There is no real need to use the 13b rear plate, in my opinion it is much simpler to make up some mounts from the existing pickup points on the 20b.

True but it's a little less fab work. Most people who do 20b swaps rebuild the engine to begin with. With the engine already separated all that is needed is to port match the secondary port of the Fd rear plate to match the 20b's other secondary ports. I think their is some other minor little things that needs to be done but I can't remember.

Do you have any pics of these custom mounts? I've never heard of anyone actually trying to make them before.


Wargasm, mounting the 20b using the Fd mounts will mount the engine a little higher in the engine bay than using a custom subframe(which lowers the engine). The higher mount + the custom oil pan is what allows the engine to clear the rack. This is also why the LIM has to be shortened for clearence. Go to nopistons and search "dragon" 20b swap for more info.


stokedxiv, if your worried about bumpsteer problems with a custom subframe, contact Rxman720b. He has a 20b with a Pettit style subframe and modified spindles. A few months ago I asked him if he had bumpsteer issues and he claimed that it was barely noticable.

I thought Dragon made his own custom subframe for his 20b? Maybe he used a 13b rear plate, but I was under the impression that he spent a lot of time fabbing up a custom subframe?

That's exactly what i'm worried about. Barely Noticable is not what i'm looking for, I want non-existant. I know, I'm picky... But i am still wondering if there are any ill-effects to mounting the engine using the 13B rear plate... I guess doing that would mean you are mounting it at pretty much the same height as the stock 13B? or is it higher? I guess you couldn't really mod the stock subframe to lower it a bit but keep the same mount points, because then you'd run into problems clearing the steering again with the lower height of the engine... :(

Yes Dragon did mod his own subframe. I can't remember the reason he choose to do so.

You wouldn't want to lower the stock subframe for clearence because then that will lower the mounting point for the front suspension control arms which are attached to it.

Here is the thread were Derrick (Rxman720b) commented on the bumpsteer of his 20b Fd:

https://www.rx7club.com/showthread.p...ghlight=linear


I have a subframe purchased from Rx7specialties which is virtually the same as the Pettit version. I will be using the bumpsteer correction kit 20b 3rd gen is offering once I finally get my damn ecu.

What does "bumpsteer" really feel like? My car feels stock on handling, so it is hard for me to compare.

Mike, bumpsteer is extreme toe in or toe out, it makes steering the car difficult because the tires are usually fighting each other in direction, do you remember the guy with the CYM 20b @ RR, him and howard coleman complain'd about how squirrly the car got @ high speeds when trying to steer the car, he had bumpsteer issues. It is actually more apparent with powersteering, making the car feel like it is floating. You don't have that problem because you steering rack did not move. ANY relocating of the steering rack from stock location will cause bumpsteer issues.

Yeah, I know what it is technically, but what does it feel like? Just driving straight and a bump in the road will jerk the steering wheel?

No, It's like trying to slowly change lanes and the car wanting to make a 90 degree turn

Also the steering is very loose

The most obvious way to 'feel' bumpsteer is changing from braking to acceleration or vice versa. The car will abrubtly dart in one direction or the other depending on how bad the bumpsteer is.

What would that have anything to do with bumpsteer? Maybe I'm not getting what you mean by loose.

Hmm. Dart in one direction.. Such as if you were to accellerate and tilt the steering wheel to either the left or right?

Yes, but as it would dart to one direction or the other (sometimes back and forth), the steering wheel would remain straight. So as a result, you would have to turn the steering wheel slightly to correct this, such as what would happen with a bad alignment. If the bump steer is bad enough, at speed when acclelerating hard or braking hard, the steering wheel can even vibrate like with a bad alignment.

That is what I meant. The shaking that occurs under acceleration.

t-von, I have a Cosmo 13B RE which uses custom mounts and the stock Cosmo mount pickup points. Subsequently, the 20B has the same pickup points in the same spot. Thus, with a custom oil pan I should be able to slide a 20B in. But Steve Kan SWEARS there's no way to clear the steering rack even with a custom oil pan...

nice can't wait to see pics of her

Restate your assumption? Could you be a tad more exact in the specification of what would/wouldn't fit with XXX parts?

A 20B can clear the steering rack, with additional modifications.

Ok, I was talking with Steve when he was down in Florida tuning my car and others. I have a Cosmo 13BRE that is mounted to the subframe using custom mounts. These custom mounts use the stock Cosmo mounting points, not the FD mounting points. I use the FD oil pan with the motor mount holes welded shut. Originally, I had wanted to simply (nervous laugh here) swap in a 20B using the same mounts and a custom oil pan. Steve said however, that it wouldn't work as no matter what he tried, he couldn't clear the steering rack. So he designed his own subframe. Now I have always known or assumed that Marcos simply used an FD rear plate (problem I don't have to tackle), a custom oil pan and a shortened LIM to get the 20B to fit. No meddling with the steering rack or the spindles. So the question is, will doing it my way, using my existing custom mounts AND a custom oil pan allow me to clear the steering rack or is there something else involved?

red-rx7 just likes to tease us :D

The main differance here is that Steve is doing his first conversion using the Acosta method. Acosta has already done the research and gone through all the heartache. I'm sure if Steve had more time to dedicate to his swap, he probably would have figured out what needs to be done to make everything fit correctly. He claims that with a custom oil pan the engine still will not clear. Some of the previous pics I've seen of the oil pan just go to prove how creative one needs to be to make it work.