hi, I am going to put a new motor into a 1983 fb which has a defunked 200HP 12aT in it.

This is the old mariah ultima show car and i guess i will continue doing a lot of research before taking the plunge. I have got some great support from steve on the s5 conversion idea, but was curious about the 20b. It looks like the 20b is a huge jump but the purpose of this post was to ask those of you who know....

Is the daily street driveability of the motors comparable or is the 20b worth the extra $5K or more just to have a unique ride?

Oh yeah, the purpose of this car is street cruising in sunny SoCal and maybe some car shows. Never drag racing...it has a body kit & too much color sanded paint I am selling my 62 corvette for this project and I want to do it right.

If we were in Australia, I could even get a reliable 12aT to put back in this creature but I wanted to run something more up to date and with a wow factor.

I have read and could conclude that a 20b conversion is not for the faint of heart but I know of some FD swaps around here and they weren't too bad and the 20b seems to be a better motor.

PS: I am also checking into picking up a 20b cosmo, with several options, as I think the 3 rotor motor is way too cool.

This request is obviously the short version, so please don't hack on me too much.....I was hard pressed to find a thread supporting any 20b conversions let alone only one thread that talked about the driveability of the 20b, thanks cliff

 

only you can decide if it's worth it or not. in the end it's your car and your coin. i'm sure you can get GREAT drivability from a 20B - it will depend on your engine management choice and tuner's skill. however, i sense indifference in your post and for that reason, i would advise going with the simpler turbo 13B swap.

 

If your doing it for the cool factor don't do it. Spending $15k-$30k to be cool isn't cool.

Just swap in a 13bt and be happy that you can drive it everyday without being worried.

 

Thanks ofr he replies. Any driveability comments, please.

The COOL FACTOR is going out to the garage just to lift the hood and looking at it. I did it daily with my corvette for 2 years when I was restoring it.

It does sound like the s5 might be the more reliable daily driver.

 

One other question is what kind of power you plan to make when its all said and done.

Pound for pound the 20B will make more power (and importantly, more TORQUE) then the 13B at any level and not be worked as hard as the two rotor. So think about that also.

However anywhere in the 400hp neighbourhood the 13B maintains a respectible lifespan.

 

If you want 400+ reliable horsepower, get a 20B. Anything less, put a 13B turbo in there.

 

no. your reliability for either engine is going to rely solely on what you put into making the engine last - engine management, tuning, maintenance and minimizing "senseless" abuse. the ONLY difference between the 2 engines on this issue is replacing the 20B if you blow it up can easily cost 2 or 3 13B-T's.

 

Finally, someone speaks the truth!

I hate the reliability topics of rotary engines.

 

Thank you. Now we are getting some where.....relatively same driveability up to 400HP ?? which is more than what I need. 200+ HP reportedly twisted my car before mods in 1983 into a pretzel. Mariah spent some long hours redoing it, though by today's standards I will be doing a bunch more reinforcing before turning it loose. Maybe the convertible aspect of it makes it a bad choice for the 20b after all.

Getting a top of the line s5 setup would be easier to live with. I will use the opportunity to make the s5 smog legal in california and pay attention to the extras to keep it alive. I don't put heavy miles on a car and I plan to respect it and my previous roties have been dreams.( 6 gsl-se, 2 gsl, 2 gs back in the late 80's)

My car has a slew of extras: recaro seats, interior, brakes and most of the suspension done and I expect to do the respeed R&P conversion as it doubles with reinforcing the front end.

I will look for a cosmo with the rest of my car money, though that is going to be a mission with a learning curve. I sure wish it was a convertible. The Japanese ones are available but RHD is a bit funky. Conversion? Resale? I will start a thread after I get started on the Fb build.