Venturer

I would to know what's exactly the power in hp of the last gen RX-7 (i think it's the 13B biturbo rotary) vs the RENESIS!
Is it more or less than the hi-power version of the RENESIS?

cueball

The FD, or last generation RX7 had 255 HP as compared to the RX8 which has 238 HP. That would make the FD more powerful than the RX8.

BRx8

in terms of the engine itself, the Renesis is more powerful considering it's NA compared to the RX-7's engine with twin turbos...now imagine a twin turbo Renesis with the correct J-Spec ECU...drool

Venturer

What is the acceleration time 0-100km/h for RX-7 last gen compared to RX-8?
And what's the maximum speed?

Red Devil

FD 0-60 ranged from 4.9 to 5.4 for the 5spd manual.

RX-8 ranges 5.9 to 6.5.

mental pimp

the rx8 is also heavier right?

cueball

By a few hundred pounds. This is mainly due to its back seat and two extra doors.

-=Zeqs=-

The FD3S also had far more torque than the FE due to the turbocharging. I forgot the exact torque measurement, but I'm sure it was over 200 ft-lbs compared to the RX-8's 159 ft-lbs. That alone will help the RX-7 leave the 8 at the lights. Once moving...the 7 still had a few more ponies, and a few hundred pounds lighter of a body. They both have close to the same amount of coefficient drag, so it's not too big of a deal there.

Venturer

So globally RX-7 performs better than Rx-8!
What a shame!

sferrett

I think the 8 meets or exceeds the FD RX7 in handling & braking, so "globally" I would disagree - the RX8 is an extremely well balanced car. (and yes, I've driven both)

The RX8 is not meant to be a replacement/next-gen RX7, it's a completely different car. So - no shame whatsoever.

Simon.

tbonerx7

At sevenstock last year or two years ago, Mazda had a test mule RX-8 and a RX-7 SpiritR on the track together. The RX-7 blew away the RX-8, truthfully because of power, but the RX-8 would carve some of the time back in the corners. Of course, there are many variables left out of the equations such as tire and suspension setups.

Stock out of the box, the RX-7 will outperform the RX-8 in almost every aspect. The RX-7 (so far) has also been more unreliable than the RX-8... though flooding occurs far less than the RX-8.

The aftermarket for the RX-7 is huge compared to the RX-8. You really would find it difficult to compare a US '93-5 model to an RX-8 because the age has changed most '93-5 7's. Most 7 owners don't have the original tires and have modified their cars.

Modified RX-7's range from 220 rwhp to 437 rwhp. They are extremely tunable cars whereas the RX-8 is a baby in the tuner market. Wait a year and some Mazdaspeed Racing and you'll see some turner parts quick!

Luckily for us, Mazda is a real car manufacturer that has its roots in the rotary and in racing. Look for them to try to race the RX-8, Renesis, and further engine/chasis development. The MazdaStar cars look really good and Paul Yaw is still working on development of the Super Charger for the GT Series and Motec is developing engine management systems for it as well. Soon!!!

oh, one more thing with the 7 vs 8... the RX-8 is a new car. You can't find a new RX-7 anywhere and the refinement in the Renesis/RX-8 is amazing compared to the RX-7. The RX-8 is like a BMW while the RX-7 is like a purpose-built racecar.

Venturer

What do you mean exactly when you say the RX-7 engine is less reliable than the RENESIS? What are the issues? Excessive wear of the apex seals after low milenage?
What are the differences between RX-7's 13B Twinturbo and the RENESIS apart obviously hp and torque? What about fuel consumption?
Does RX-7 has electonics aid such TCS and DCS?
Is there a way to improve RENESIS hp at the same level of the RX-7 only by tuning electronics without physical mods?

wakeech

the reliability issues come from overengineering in the sequential turbo systme, and cost cutting.

fuel consumption is a hard call, 'cause Mazda doesn't have the fuel curves yet sorted for the RENESIS (they are far too rich as they are). as fuel consumption goes, they're fiarly comparable right now (the RX-8 should beat it), but as always the biggest variable is how you drive your car.

differences between the engines are vast, vast, VAST. to really explain them all would take pages and pages, adn you'd need to learn a lot about a lot of things before i could explain it all to you anyway, so i'd suggest going and reading up on both. the only thing common to them is their displacement and fundamental mechanical motions.

the FD doesn't have either TCS or DSC, but does have a TorSen differential (which is calibrated to a more aggresive setting, stock, than the RX-8).

yes, there are ways to improve the performance of the 13B-MSP (RX-8's engine) to match the peak horsepower levels of the 13B-REW (FD3S RX-7's engine)... look into user Canzoomer's ECU piggy back modification thread. his progress is astounding (just like i knew it would be, once we learned what was wrong) and he's starting to ship the first units soon.
but this is not to say the engines would be indestinguishable: they're still extremely different units which motivate vehicles with entirely different characteristics.

and for the record, torque numbers mean nothing. out of a dig, it's the low rpm horsepower that does all the pulling.

hornbm

iTrader: (1)

And how exactly did you determine that a modded FD can have no more than 437RWHP? And for that matter, how did you come up with a number like 437 anyway???

boothguy

Just to add a little more light to the reliability issues of the 3rd gens, it kinda went like this:

Mazda polled US carbuyers late in the production run of the 1st gen about what kind of sportscar they'd like to see Mazda produce next: a "practical" sports car (which became the second gen) or a "no-compromises" sports car (which became the third gen).

Problem was, in designing the low sexy shape, there was very little space left over to fit in all the mechanical bits that were needed. Everything had to be engineered to fit a specific piece of space -- kind of like a submarine. And because the rotary makes a lot of heat on its own, adding in twin turbochargers that make a lot more heat, and a pre-cat that makes some more still, caused the engine bay to be a VERY hot place.

That heat caused a lot of premature aging and failure of ancillary rubber and plastic parts - not to mention some engine bay fires on '93s where oil pooled on the engine exterior surfaces. If not treated carefully, the heat also coked and ruined the bearings on a lot of turbo assemblies and cooked some internal water passage O-rings which is a terminal engine failure. And even on cars that have been cooled carefully, the rear mainshaft oil seal gets cooked and crumbles.

Add to that list of headaches the point Wakeech mentioned earlier about the incredibly complex turbo control and general engine management electronics and you start to get the picture.

Oh - and don't forget that because their performance gets your attention like a good smack upside the head, most of the #gen RX7s were either stationary or floored - no in-between. And that helped them get a slightly skewed reputation for unreliability. In my opinion. As a longtime owner of one.

Venturer

So i know RX-7 has many reliability issues!
What is the averange life in km of the 13B-REW Twinturbo engine before it needs to be reassembled?
I think RENESIS's warranty is 240.000km (in Europe); a very long life for a rotary engine!

One more question: What are max RPMs for the 13B-REW Twinturbo? Are they the same of RENESIS?

wakeech

it depends, but 100 000 kms is the horror story you hear (3 or 4 years regular use). i say it depends 'cause some get more, some a great deal more than 240 000 kms without a rebuild (especially on older all-motor 12A's and 13B's), but i suspect those owners would get that much mileage out of any engine.

the 13BREW's redline in the Series 7 was 8500 rpm, i believe, whereas the 13BMSP's is a conservative 9000 rpm (with buzzer at 8500, and limiter kicking in ~9300 rpm)

Roar 629

my 13b-rew went out at 89000 miles.

PoorCollegeKid

Um, it's actually the torque that's put down to the wheels that does any and all of the pulling. Torque is a measurement of force, and force creates an acceleration in most cases. HP is a measurement of power, which is work done over time, which really has no affect on the acceleration of a car, but is useful in considering the top speed of a car, how to gear a car for best acceleration and top speed, and an engine's high rpm power characteristics among other things. A car will accelerate at a rate that is directly proportional to its torque curve, not it's power curve. That's why you RX-8 owners feel a very smooth, linear, constant acceleration with no real surges or jerks in it. The torque curve of the Renesis is very flat and smooth, while the power curve climbs rather steadily. If acceleration depended on the power of the engine, you would feel the acceleration increase steadily and be pushed back in your seat very noticeably harder and harder as the rpms rose, and this just isn't the case. If you've driven a turbo car with noticeable lag or a VTEC/VVTL-i powered car, you can tell when the torque curve rises because of the sudden kick the car has when the boost/added timing and lift kicks in.

wakeech

i know that, but i was making a point about measuring from the engine.

the deal is that when you're measuring from the engine (at the flywheel) all that matters is horsepower because it runs through the transmission. what you have is some amount of effort yea fast, but that can all get screwed around so that it's all the same in the end at the wheels (about which you're exactly right).

150hp will accelerate the car at the same rate, no matter the rpm it's generated at (either lots of torque at a low engine speed or a little torque at a high engine speed), if your speed reduction ratios are proportional. i could do the math, but it's 2.30 in the morning, and Buger, Rich, and a few other people (me included, i guess) have gone over this so many times i wanna barf.

so yes, torque at the wheel actually does the pushing, but torque at the wheel is derived from horsepower/gearing ratio, and thus when measuring at the engine (before the transmission) power is all that matters.

zerobanger

The rx-8 is every bit as fun to drive as the FD. Its a very inspiring car. But dont try to compare acceleration.

Strangly enough the FD gets much better gas mileage. go figure.