Datsun Roadster Forum-311s.org

The wife and I lived in Spokane, WA for 1 year. I met two guys who owned stock and swapped roadsters. First guy had an automotive shop and he had done several swapped roadsters, one of them a 13b rotary. Said the customer was happy and the guys most difficult problem was the heat these little engines put out and routing the exhaust pipe so that the cab did not get too hot. The other guy was a wrench also and owned an L20b swapped roadster that fit as though it was made to order, hood closed normally, etc.

Anyone on here running a 13b that can comment on how it works, performance, etc.?

Yes!
Done many times.

Thanks Alvin, if anyone would know it would be you! Maybe an owner of one could post some time with their impressions, etc.

I almost bought one years ago. Probably should have, as it was a nice car. The numbskull thought that a stock 13B could turn 11,000 RPMs, and tried. It did not end well.

Do it!!!!

13b is a very neat engine. I had a ported 13B Rx3sp way back in the day. It was a blast. Fast as a lot of corvettes.

Unless turbo, I don't know how anyone got one to 11k?? Mine ran out of steam somewhere over 8k so it was time to shift way before 11. 4-8k it pulled like a littleV8.

I think the biggest challenge you will have with a swap is the exhaust. Not only is it on the wrong side....and they make a ton of heat, if you look at all those old mazdas, they had giant exhaust cans to quiet them.

If you use a standard muffler of almost any type, not only will the heat kill it, it will be rediculouly loud. The SP had 2 pre-silencers and a turbo muffler. Even with 3 crappy mufflers, you could literally hear it a mile away.

It had a 50mm Mikuni on it. I think some of the "off throttle" backfires may have cracked some windows in the neighborhood. Serious insanity

I am seriously contemplating swapping to a 20b turbo in the future. A bridgeported 13b would also be very cool, but they are not very streetable and get worse mileage than a 70’s muscle car.

JT68 wrote: Fri Jun 19, 2020 4:59 pm
I think the biggest challenge you will have with a swap is the exhaust. Not only is it on the wrong side....and they make a ton of heat, if you look at all those old mazdas, they had giant exhaust cans to quiet them.

If you use a standard muffler of almost any type, not only will the heat kill it, it will be rediculouly loud. The SP had 2 pre-silencers and a turbo muffler. Even with 3 crappy mufflers, you could literally hear it a mile away.

It had a 50mm Mikuni on it. I think some of the "off throttle" backfires may have cracked some windows in the neighborhood. Serious insanity

IIRC, one of the tricks was to use 0.125 wall tubing for the exhaust. They are loud!

datsunrides wrote: Sat Jun 20, 2020 11:58 am I am seriously contemplating swapping to a 20b turbo in the future. A bridgeported 13b would also be very cool, but they are not very streetable and get worse mileage than a 70’s muscle car.

The bridgeport didn't really affect driveability, it purred, but you are right about the mileage, that was pathetic/expensive.

Some photos I've taken and collected over the years:











I'm not a rotary fan, but to each their own....

JT68 wrote: Sat Jun 20, 2020 1:56 pm

datsunrides wrote: Sat Jun 20, 2020 11:58 am I am seriously contemplating swapping to a 20b turbo in the future. A bridgeported 13b would also be very cool, but they are not very streetable and get worse mileage than a 70’s muscle car.

The bridgeport didn't really affect driveability, it purred, but you are right about the mileage, that was pathetic/expensive.

In driving a couple bridged RX’s I found them to be quite peaky. Tons of power but up there in the power band, just like a ported 2 stroke. Not that I would call a stock 13b a torque monster.

I hear you guys. My 72 rx2 was an awesome car. Fast when you wanted it and quite as hell on the highway. I think there was a commercial way back that said the rx2 was quieter than a Cadillac, I lived it so I believe it. BUT, as you point out, when I romped on it a lot I could get as low as 10 mpg!!
And after thrashing that car mercilessly the apex seals gave out, it started smoking a lot, so I sold it and bought my lst roadster, a porthole hardtopped Red one.

My 73 RX2 seemed attracted lots of tickets. Gas was cheap back then, tires kinda sucked tho. Loved that rotary engine...no seal smoking till about 105K.
The rust finally got it.
Put one the track and wished the stock brakes were a little better to haul her down.
Sure would like to have one of those again.
Also wished I had a few pictures of the car.

My 2 cents DON'T
think your buying a old but very good cond engine ? How ?
I'm not an expert. on the Wankel but in 82 a tech that worked at our Datsun dealer went up to Mazda , and became the top RX 7 engine rebuilder ( they did not attempt
Other model roteries) then camecto our shop for VW. - we had VWs also - this guy had been to school 3 times on rebuilding the 12a , he said he rebuilt about 6 to 8 but only 1 seemed to be lite on oil burning after.
Stated the case where the rotor slides rub would get gaulded and warped and there is no practical fix .

The other expert on the kans side trashed him. Telling customers of his problems / comebacks. Then the Kans guys 5 rebuilds " hit the fan " with oil consumtion lower compr. And he quit instead of having to tear then down to try new options the Mazda DSM cam to the shop and finally offered enough $$ to get our guy back , but I talked to him yrs later and he really couldnt fix them .
Stating the dirt that is able to get past the filter is thrown against the case and just keeps going round and round ..
A stick trans has as much power as a 4 banger with a plud out until 4 k especially up a slope from a red litec
Many a cop set back and nabbed a rx7 as he got power from that set up .
That 11k may mean the rotors as they turn 1.4 ? 1.6 X the eccentric shaft
I would go with the sr or 2.4 before considering a 13b

We had a 1974 RX-4 Wagon. This was the first 13B-powered Mazda stateside.





I really loved driving it. Even with the stock carb and Racing Beat exhaust/intake it made 142hp/129tq at the wheels. Not peaky at all, in fact it made over 100lb-ft of torque from 2k to 6k:


I remember it being surprisingly smooth revving to redline, and my goodness that sound! Super rowdy. We had 4 mufflers on it:



Here are a few videos to give you an idea: