2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

20B swap

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Old 02-04-02 | 04:36 AM
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Coolidge's Avatar
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From: Yorkton, SK, Canada
20B swap

What special mechanical modifications need to be done to a TII to swap in a 20B?

I know about the engine management, intercooler, fuel system, etc needs, I just want to know about special modifications done to allow the engine to be mounted in the car.

This is what I've read needs to be done to allow the swap:
- alter front sway bar (or replace it with a custom one)
- remount radiator to allow more room (and replace with bigger/better rad)
- possibly alter motor mounts???

Is there anything else?
Old 02-04-02 | 01:12 PM
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From: Charlottesville, Virginia, USA
First of all, I would like to point out that starting with a TII will make things much easier for the conversion. You have just about everything correct so far, but the engine mounts need to be replaced with custom mounts or with specially-made mounts from K2RD. Also note that relocating the radiator will probably also require you to relocate the oil cooler.

In addition, you will need:
Custom-made downpipe (I also recommend a new exhaust system)
Custom-made transmission block plate/starter mount
Custom-made or modified intake elbow
Custom-made or modified TID
Gutted IC scoop interior
Aftermarket tachometer or modified TII tach
Boost controller (if your EMS doesn't have one)

Other issues:

The stock thermostat housing will not clear the hood. Options are custom-made dual thermostat housing (this is what I did), replace stock water pump with lesser-flowing 13B pump, replace stock water pump with electric pump, etc.

Oil metering. Optons are to run the OMP with an aftermarket ECU, install a 13B front cover and mechanical OMP, run pre-mix, etc.

Ignition system. A lot of this depends on whether or not your 20B comes with a wiring harness or not. As far as I know, only the Motec EMS units will run the stock Cosmo coils. You may want to check with other EMS manufacturers. Like most 20B engines, mine didn't come with the stock coils, so it was a moot point. If you don't use the Cosmo coils, then you will need to figure out a custom ignition system of your own.

I can't think of anything else right now, but I'm sure that I am forgetting some things. Try a "20B" search on this 2Gen forum for more info.
Old 02-04-02 | 03:35 PM
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Sweet thanks! some of that I knew, but wow! that is exactly what i wanted to hear
Old 02-04-02 | 03:44 PM
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From: https://www2.mazda.com/en/100th/
oh and dont forget that if you use the stock turbos, the intake and the exit for the turbos wont clear the hood. also you need to make vacuum and pressure tanks for the sequential system if you want to keep it.
also use the search there is almost all you need to know on there. oh and there are no wiring diagrams or vacuum diagrams for any of the stock stuff so even if you have the stock coils doesn't mean you know how to wire them up

hey evil did your engine come with the stock tstat cover?? did you check the diaphram in it? ive checked 3 and they are all bad

mike
Old 02-04-02 | 04:10 PM
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Originally posted by j9fd3s
hey evil did your engine come with the stock tstat cover?? did you check the diaphram in it? ive checked 3 and they are all bad
Yes, but I didn't use it. Actually, I had a mechanic start modifying it, but it just wasn't working out so I had SPiN Racing make me a custom dual thermostat housing out of billet aluminum. The custom housing accepts 2 RX-7 thermostats. Early fabrication pics here:
http://home.tampabay.rr.com/spinraci...tor/index.html

Last edited by Evil Aviator; 02-04-02 at 04:14 PM.
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