FT86 vs. RX-7 FD

[Purdue FR-S]

Guess I'll have to wait for the 15 year import rule

[vh_supra26]

Originally Posted by Lido

I never realized how many of us also own FD's but I am in the same boat.

Nice FD, good to see a follower owner here.

[ramiram1984]

Originally Posted by FutureFT86

Hey guys,

Besides the S2000 which I think is an absolutely great car, I think the next best thing besides the FT86 is an FD rx7. most of the specs I found online show this car is not too much larger than the ft86 and it not much heavier either (around 2850lbs). The height of the rx7 is also lower and thus I suspect the COG may be lower. I just think this is one car (although almost 20yrs old) can rival the ft86. Now I may be comparing apples to oranges here but I would just like to see what you guys think.

Thanks,
Mike

Could compare this to the FC, not FD. Sorry.

[drift86]

Originally Posted by tahdizzle

While rotary engines are cool....

But gas mileage and maintenance..

The engine was actually the worse part of the FD in my opinion. There's nothing that it does that a modern piston engine can't do better.

I had one of the last FDs ever made. The Spirit R from Japan with all the goodies.

Stock vs stock, the 86 actually handles much better than a FD. On the limit (very high limits), the FD has terminal understeer and a lot of bodyroll. Whereas the stock 86 is one of the best balanced stock cars I have ever driven on a track.

[fatoni]

Originally Posted by drift86

The engine was actually the worse part of the FD in my opinion. There's nothing that it does that a modern piston engine can't do better.

I had one of the last FDs ever made. The Spirit R from Japan with all the goodies.

Stock vs stock, the 86 actually handles much better than a FD. On the limit (very high limits), the FD has terminal understeer and a lot of bodyroll. Whereas the stock 86 is one of the best balanced stock cars I have ever driven on a track.

probably weight, size, engine speeds, power per liter but it definitely has drawbacks. i imagine that if the rotary motor had half the time and money invested in it, it would be on par if not better than a piston powerhouse.

[drift86]

Weight: A LS1 weights less than the 13B
Engine speed: It revs to 8000rpm. Nothing special there.
Smoothness: I had my 13B rebuilt and balanced. It was smooth but not noticeably smoother than a good modern piston engines.
Power per litre: A 13B is not the same as a 1.3 litre 4 stroke engine. Its the equivalent of a 2.6 4 stroke engine

It was a great engine at the time it was released in 1991. Its just a bit outdated now.

But the rest of the FD is so good (chassis, design, suspension, light weight) that it is still comparable with modern high performance cars made 20 years later.

[Deslock]

Originally Posted by drift86

Weight: A LS1 weights less than the 13B
Engine speed: It revs to 8000rpm. Nothing special there.
Smoothness: I had my 13B rebuilt and balanced. It was smooth but not noticeably smoother than a good modern piston engines.
Power per litre: A 13B is not the same as a 1.3 litre 4 stroke engine. Its the equivalent of a 2.6 4 stroke engine

It was a great engine at the time it was released in 1991. Its just a bit outdated now.

But the rest of the FD is so good (chassis, design, suspension, light weight) that it is still comparable with modern high performance cars made 20 years later.

An LS1 weighs more and is larger than the 13B. The weight of the LS1 + t56 is very close to the 13B + FD twinturbospaghetti + FD tranny.

23 years ago, 8000 RPM was special. Not many priced-for-mortals-stock-street-cars could do it.

A 2 rotor engine felt smoother than the typical 6 cylinder piston engine, and the rotary loved to rev.

In terms of displacement, a 13B can be considered akin to a 1.3L or 2.6L, depending on how you define it. Doesn't matter... it (more-or-less) was the size/weight of a 1.3L, had the output of a 2.6L, and had the fuel consumption of a 3.9L. For automobiles, piston engines have improved since then (pretty much across the board: weight, output, emissions, efficiency, cost), so that generalization wouldn't really hold up today.

The rotary has died off anyway, and I don't see it coming back. Mazda talked up the next generation 16X years ago, but it's vaporware. At this point, it seems the high emissions and fuel consumption of the rotary were too much to overcome.

[ZDan]

Originally Posted by fatoni

probably weight, size, engine speeds, power per liter but it definitely has drawbacks. i imagine that if the rotary motor had half the time and money invested in it, it would be on par if not better than a piston powerhouse.

I think that a large part of the problem is that it rejects so much energy from fuel as heat due to broad rotor faces. I think this is an inherent "feature" of the rotary. It does offer kick-ass power/size and power/weight, but the fuel economy disadvantage is WAY more significant.

Originally Posted by drift86

Weight: A LS1 weights less than the 13B
Engine speed: It revs to 8000rpm. Nothing special there.

13B is significantly lighter than an LS1, and the Renesis revved to 9000.

Smoothness: I had my 13B rebuilt and balanced. It was smooth but not noticeably smoother than a good modern piston engines.
Power per litre: A 13B is not the same as a 1.3 litre 4 stroke engine. Its the equivalent of a 2.6 4 stroke engine

Always have to pipe in when this comes up. The 13B is indeed a 1.3 liter. It has the advantage of aspirating its full displacement every crank rev, like a 2-stroke. However it also loses a lot more to heat, so it doesn't make twice the power of a same-displacement 4-stroke piston engine. More like 1.5x.

IMO, it would make more sense to call a 2.6 liter 4-stroke piston engine a 1.3 liter, since that's what it displaces every crank rev, than to call the rotary a 2.6 liter.

Originally Posted by Deslock

An LS1 weighs more and is larger than the 13B. The weight of the LS1 + t56 is very close to the 13B + FD twinturbospaghetti + FD tranny.

Same vs. same LS engine swap into an FD usually adds 50 lb. Mine, with a roll bar, bigger wheels/tires/brakes, Accusump, etc. weighs ~2850 lb. empty, ~2980 full of fuel (20 gallon tank!). About 100 lb. heavier than a stock FD. FWIW...

In terms of displacement, a 13B can be considered akin to a 1.3L or 2.6L, depending on how you define it. Doesn't matter... it (more-or-less) was the size/weight of a 1.3L, had the output of a 2.6L, and had the fuel consumption of a 3.9L.

Actually, the power is more like a 2.0L at similar revs. F20C is the nearest piston-engine equivalent. Again, ~1.5x equivalency factor works well. Fuel consumption is way way WAY worse than a 3.9L piston engine though. My 6.0 FD gets WAY better mileage than any rotary FD ever did! On the highway, anyway...

The rotary has died off anyway, and I don't see it coming back. Mazda talked up the next generation 16X years ago, but it's vaporware. At this point, it seems the high emissions and fuel consumption of the rotary were too much to overcome.

It's a neat engine, but inherent fuel inefficiency isn't a problem easily overcome. I still think they should sell a special limited-run rotary Miata, though. That would kick ass...
If they were to build a new FD-like car, I think they should do something like a compact 2.5 liter V4 that revs to 9000 and makes ~300hp NA in a sub-2800 lb. fixed-roof coupe. yeah, that'll happen...

[DarkSunrise]

Originally Posted by drift86

Smoothness: I had my 13B rebuilt and balanced. It was smooth but not noticeably smoother than a good modern piston engines.

Interesting. I had a chance to ride at the track in a lightly prepped RX-8. From an NVH perspective, it felt really smooth, like it could rev well past 9000 RPM. Maybe even smoother than BMW's lauded straight-6 in the E36 M3.

[Deslock]

Originally Posted by ZDan

Actually, the power is more like a 2.0L at similar revs. F20C is the nearest piston-engine equivalent. Again, ~1.5x equivalency factor works well. Fuel consumption is way way WAY worse than a 3.9L piston engine though. My 6.0 FD gets WAY better mileage than any rotary FD ever did! On the highway, anyway...

It's true that the F20c's output was similar to the RX8's 13B-MSP's (the F20c had more high-end, while the 13B-MSP had a bit more low end). But the F20c was hand-built and pretty extraordinary (120 hp/L in a reasonably priced N/A), and also came ~9 years after the introduction of the FD.

The discussion before was really about the late 80s and early 90s (and as I mentioned, piston engines have since improved).

Many piston engines 25 years ago made ~65 ftlb/L while the 1989 RX7 made ~70 ftlb/rotor, giving it approximately the same low-end output of a 2.1L or 2.2L. But the rotary wasn't intended to run at similar revs... the 2.8L VR6 (well regarded in 1989) made 172 HP, which equates to 160 HP if it had been a 2.6L (what the 1989 FC made with it 13B).

But there's a reason I qualified my 1.3/2.6/3.9 comment with "more-or-less". One could argue that 1.6/2.4/5.0 is more accurate, but whatever... we all agree that rotaries were nifty and tiny, but thirsty (and YMMV, literally).

[MokSpeed]

The FD is super sexy, but I prefer pistons over Doritos on a stick.

[ZDan]

Originally Posted by MokSpeed

The FD is super sexy, but I prefer pistons over Doritos on a stick.

Hence:

[SWP BRZ]

I still plan to pick up another FD RX-7 in the future and another FC. I still love these cars even though I now own a BRZ. Nothing in my mind will ever compare to them but the BRZ does a great job at it.

Owning an RX-7 is a cult/obsession thing. Nobody will ever be able to understand you or why you waste all the money on the car. But nothing is better than that rotary sound.

[malave7567]

Originally Posted by SWP BRZ

I still plan to pick up another FD RX-7 in the future and another FC. I still love these cars even though I now own a BRZ. Nothing in my mind will ever compare to them but the BRZ does a great job at it.

Owning an RX-7 is a cult/obsession thing. Nobody will ever be able to understand you or why you waste all the money on the car. But nothing is better than that rotary sound.

Agreed. I still miss my FC