Silver 929

First off, I am new to this board. I drive a 1992 silver 929. 223,400+miles on the original engine. I have had the same tranny problems as many people did. However, the engine is in tip top shape.

Now on to the point of why I am here. The engine does seem to be tired. It needs to go on to a better place. Have looked into the 20B, and here is my question:

Can the 20B be put in the 929 (with the Cosmo tranny)? If it has been done, who has done it, and how can I reach them?

Jeff20B

iTrader: (13)

Forgive my ignorance, but is your car rear wheel drive?

Madman

I hate to rain on your parade but I think the chances of doing that are slim to none. First of all I believe the 929 is FWD. Now if you go up to the right corner of the screen and do a search for "20b" you are going to find a wealth of information on how hard it is to do the swap with an FC or FD. I dont know of anyone attempting this with a 929, but very few if any at all. Also plan on about 10-20k for the swap.

j9fd3s

iTrader: (3)

they had the 13bt in the previous 929. and all of the 929's are rwd, i would bet that the jc cosmo and the hd 929 are similar enough so that it could be made to work. the easiest way to do it would be to get a whole front cut from a jc cosmo and swap everything over.

mike

Silver 929

The car shares nothing with the 626/MX-6!!!! Look up your Mazda's!!!!!!!! The engine is barely similar.

This is the car's stock setup:

3.0 V6 RWD 3 speed auto with overdrive.
Bore and stroke: 3.59 X 2.99 with roughly a 9.0-9.2 compression ratio.
195hp/205ft-lbs of torque
It has now 223,7XX miles on the original engine.

The 626's V6 was a 2.5L with bore and stroke: 3.33 x 2.92 inches

Mazda bored out their 2.5 (and a little stroke) to make the 3.0L in my car.

The 1992 929's (pictured below on 3G RX-7 rims) is very very similar to the Cosmo chassis of the same year. Theoretically the drivetrain setup is similar. The transmissions are different as well as the rear diff., however these are going to be swapped also.

I need some intelligent answers here. Serious/knowledgeable posts only. I am seriously trying to get some info on whether or not the 20B is a good idea/feesable idea.

Silver 929

This was the idea that I had tossed around. There was one up on the trader a while back, but I couldn't get it in time.

smith88

I was searching for 20b's the other day and I never could find out what HP the engine puts out stock. Also, are all of them twin turbos? I saw quite a few of those sequential twin turbo 20b's, but all of them were modded to 600+ HP. I want to know if there are any other 20b's and what the stock HP is on them.

Thanks If anyone knows

peejay

You may think is is funny but I've only seen three or four different 929's in my life and all of them had over 275k on them, one had 297k and another had 315k on it... the cars all looked like new inside and out.

I've been thinking about putting a turbo rotary (probably 13BT because 20B is far too expensive) in a 929 BUT the problem is that 929s are fairly rare (like i said only worked on 3-4 of 'em ever) and I've NEVER seen one for sale so I don't even know how much it'd cost me to get one, but judging by the ones I have worked on, it's gonna be a looooong time before I can get one with mechanical trouble.

Mazda missed the boat big-time by not going through with the Amati (?) division... can you imagine a US spec Cosmo or Luce... maybe even one with the 20B engine! Can you say "Q45 Eater"?

peejay

(double post error)

Silver 929

That's odd. There are 929's a-plenty here in South Carolina and Georgia. I see them all the time. I see a lot of them for sale too. And which years are you talking about as far as the high mileage, and were those miles all on the original engine? Mazda in CA didn't believe the mileage on mine when I called last year to order some parts directly.

Jeff20B

iTrader: (13)

The answer is 280PS stock. That is similar to horsepower. Craig's rotary page is down, as well as a different page called Rotary Power which contained some of Craig's writings.

Check out https://www.rx7club.com/forum/showth...threadid=44401 for a 20B and tranny that are for sale.

You could get away with natural aspiration if you needed to (lack of money or whatever). The rotors are 9.0 compression which is still high enough to get decent power from NA. Infact, older 4 port NA rotaries were only at 9.2 compression. The GSL-SE is at 9.4.

Yeah, check out 3rotor.com and look at the build of the HB Cosmo. Then check Rob's 20B 4 door HB Cosmo in the 3rotor group section.

That oughta be enough info for you at the moment.

Evil Aviator

I don't think that this has been tried yet. You could be the first.

I don't know much about the 929, but if there were models with a 13B, you may want to check to see if it was a Cosmo-type 13B which has the same engine mounts as a 20B. If it did, then you could probably track down some engine mounts. Otherwise, you may have to make them yourself. If the 929 20B swap is anything like the RX-7 20B swap, then prepare for lots of fabrication, frustration, and about $10,000-20,000 for the mod.

Note that the 20B EMS, transmission, and ignition system are all made for each other and work as a unit. If you want to use one of these parts, then you need to use all three.

Yes, they were all twin sequential turbocharged engines (20B-REW), and they were all mated to an automatic transmission. Mazda rated them at 280ps @ 6500rpm / 41.0kg-m @ 3000rpm (276bhp @ 6500rpm / 296 ft-lbs @ 3000rpm), and the redline was 7000rpm.

http://www.dmrh.com.au/
http://www.geocities.co.jp/MotorCity/6881/

Bitchn7

I say some people are pretty ignorant when it comes to cars they don't know anything about.
Your 929 is known as the Sentia in Japan.
There is a guy here in NZ that has fitted a S4 (sec Gen) 13B turbo and 5 speed g/box to one of these.
judging by the room left over, a 20B will fit. Why bother with the auto, put a manual in it.
There is also another guy (one of the aboves friends) who has fitted a 5 speed to his 13B JC Cosmo.
We have a 20B JC Cosmo and wouldn't mind doing it to our car as well.

pretty stylish cars, just need some grunt I think.

Big_Will

Hey,

I talked with a guy a little about this on another thread. But, what I wanted to do what the New Zealanders are doing and just put a manual tranny on the 20B and carburate it. It seems like a simple 20B beater thing (they had one in a Starlet). Is this practical to do? What would it involve? Thanks.

Will

Jeff20B

iTrader: (13)

Well, the compression ratio is ok for NA at 9.0:1, but I'm not sure how many/how big the carbs need to be.

Big_Will

Hey,

well the big question is this: Can I do away with a complex electrical system by carbing the engine? The goal with using the carb setup is just ease of installation. Evil Aviator said the tranny and stuff is all one system. So is it easier to just not use the system and go with carbs and an FD transmission?

Sorry if any of this seems stupid, I'm new.

Will

Evil Aviator

The electrical system isn't complex if you use an aftermarket EMS. The thing is, the engine already has a perfectly good EFI system and twin turbos on it from day one. A decent aftermarket EMS and ignition system will cost you about $2,500. If you convert it to a carb, then you are looking at about $800 for the carb, and $500 for the mainfold, plus all that additional labor of removing the turbos and manifold, etc. So basically, you get the EFI, twin turbos, a whole lot more horsepower, and a lot less hassle for $1,200, which I think is a very good deal. Of course, I don't think you could use the Cosmo transmission with such a setup, but then again I don't think it will work with a carb setup either.

The viable options for a 20B conversion depend a lot on what you get with the engine. Most I have seen do not come with the wiring harness, coils, or ECU, and they usually have some type of physical damage to the intake system. Some have useable turbos, while others need rebuilding.

BTW, last weekend I found out that the Motec M4 will run a 20B with theh stock JC Cosmo coils.

Bitchn7

The Starlet in NZ with the 20B in is running a fuel only ECU and he has use kiwi inginuity to run the ignition. He has made his own custom tripple throat throttle body too I am told.

There is also a front wheel drive mid - late 80's 323 sedan with a 20B PP in it. It has been made rear drive and runs two IDA webbers with one throat made redundant, also has kiwi home grown ignition set up.