ZeroBanger

I have no doubt the FD is capable of 13.5 in bone stock form But not with me driving, lol.

MazdaRx7Racer4Life

I could not agree with you more dan. Superiority of an engine is defined by the terms the driver chooses to judge it by.

ZeroBanger

Im not trying to shove the renesis down anyones throat, but how can dan say the 13Brew makes more HP and torque? The only reason it does is because of the turbos. Everyone who likes rotaries should be happy that the engine has been improved. Someday mazda will likely do some sort of forced induction or increase the displacement and the engine will be even better.

jimlab

Allow me to replay that for you and let's see if you can spot the contradiction in the second sentence which answers your question in the first... ready, get set, go.

You can't have it both ways. It either does or it doesn't make more power. Since it so obviously does, you don't get to play the "what if the 13B-REW wasn't turbocharged" game, or the equally popular "what if the Renesis was turbo/supercharged" game. We can play "What if" games all day long, but if we're going to start that happy horseshit, then why don't we skip right to the "what if the McLaren F1 was only $10,000 and came with a Playboy Playmate" game and really use our imaginations for something worthwhile?

The 13B-REW and the Renesis were delivered from the factory unequal in the power department. Why are you unable to just admit that and live with it? Why does everything you have just have to be better than everything else, and now that you apparently have an RX-8, it has to be better than everything else including the FD?!? I'm sorry, but you're damaged goods. Brain broken. Loco en la cabeza. Do not pass Go, do not collect $200, and I really think you should get that CAT scan soon...

The Renesis is NOT the quantum leap forward that you want to think it is, despite all the hype Mazda tried to raise around it. It may be a noticeable improvement over the naturally aspirated 13B of the late 80s and early 90s, but it should be. Everyone bitches about how little R&D the rotary engine gets. Well, take a look, because THIS is what the last 10+ years of Mazda's R&D resulted in. A rotary engine that's barely an improvement in fuel economy, a step backward in power, and a bit lighter. So what?

Next...

Elegant Black Monster

Well, this needs to be said.

jimlab

Don't make the mistake of assuming that the purpose of arguing is always about trying to change someone else's opinion. Sometimes it's satisfying just to make them look stupid in front of other forum members.

Choser

Putting a Renesis in an FD, simply swapped over, is indeed pointless. You would have a slower car. I don't think anyone would disagree with that.

But, it may indeed be a better "platform" to turbocharge. Perhaps not as is, but with modifications done to it. Of course, the market is young and people have not yet seen what it is capable of. I was reading the other forum and someone considered 13B-REW rotors in the Renesis, and using that as a starting point.

There is no doubt that technology improves over time, and 10 years for Mazda must yield something. Unfortunately, the sports car market isn't the same today as it was a decade ago. But, just like Piston engines or any other technology, things do indeed improve. Were Mazda to create a FI Renesis engine, I would place my bets that it creates more HP/tq from the factory, is more reliable, more environmentally friendly, and will yield higher power in the long run after they are fully tuned. I think this is almost a given.

To me, this argument between jim and zero almost seems like you guys are arguing different points. Yes, the Renesis generates less power overall and would be a poor choice to swap into the FD, and yes, the Renesis is a better engine technologically than a comparable N/A rotary from a decade ago. Unfortunately that engine never existed for comparison purposes.

MazdaRx7Racer4Life

The renesis is an awesome engine, I agree, but its stil a 13b, what separates it from a regular 13b I think are the size and types of ports. The basic setup is the same. If the renesis were turbo, it would come out at a lower compression and maybe at around 260hp,. ut its potential for tuning would be great. Again, an NA never has the tuning capabilities a turbo car does, so even though I am a rotary freak, a rotarty is a rotary, na's come with almost the maxed out stock hp, turbo does not.

FDNewbie

iTrader: (10)

Jimlab, I understand your point, but could you entertain this idea/concept, and correct me if I'm wrong...

Yes, the 13B-REW only came turbocharged, and the renesis is N/A. Thus, technically speaking, you can't directly analyze the outputs of the respective engines ONLY (minus turbos)

If you're really interested in evaluating solely the performance of the engine (again, minus turbos), wouldn't the only way be to strip the 13B-REW of it's turbos, and compare it to a Renesis engine that has had concomitant engine work done to be at same level as the 13-REW?

(the internal engine work im talking about is trying to take into account tuning capability of a turbocharged engine, vs. a NA engine which is virtually tapped out...)

The other option would be to build the internals of the Renesis so it could be effectively turbocharged, and then compare the 13-REW turbocharged w/ a turbocharged Rensis?

Point being, to directly compare one engine's output to the other, wouldn't they have to be the same platform (NA or turbocharged), and either "Stock" or "modified internals" ?

jimlab

The only important point here is that the 13B-REW was only available turbocharged, not naturally aspirated. Zero is trying to compare a hypothetical engine (and making up power numbers for it as he goes) that never existed (an "NA 13B-REW") to his Renesis. It's an exercise in futility, because it has no relevance to results in the real world.

Why not just compare the two engines as they left the factory? Those are real world engines with real world outputs that can (and should) be compared. Anything else is as silly as saying "What if Top Fuel engines were naturally aspirated... how much horsepower would they make then?". It's absolutely pointless. Top Fuel engines are supercharged, end of discussion.

No one is ever truly interested in evaluating engines fairly, least of all ZeroBanger. Personal bias always plays a role. He's one of the people who will fight you to the death on a fair comparison of rotary displacement to piston engine displacement, regardless of the FACT that an NA 1.3L rotary engine ingests roughly as much air as a 2.6L 4-stroke piston engine. He just won't consider it, or even admit to the possibility, because it would negate the high hp/L bragging rights (and therefore some of the "superiority") of the rotary engine. Are you starting to get the picture? NO comparison that doesn't favor what he wants favored can be allowed... and that's not fair.

ZeroBanger wants to tip the scale in favor of the Renesis by comparing it to something that never existed. The 13B-REW was never designed as an NA engine, and it's not fair to say "just remove the turbochargers", because the compression ratio is of necessity lower because it was designed to be turbocharged. So we'll take this one step further... just swap NA rotors in, right? Wrong. The engine was still not designed for naturally aspirated operation, so all you've got now is a higher compression NA turbo engine with the wrong ports, intake (and who knows what else) to make decent power in naturally aspirated form. Are you starting to understand why you can't compare an "NA 13B-REW" to the Renesis but why he wants to?

When someone starts talking about a "fair" comparison of engines, you can immediately assume two things; they know damn well that their engine suffers in comparison, and they're trying to invent or fabricate a situation where it doesn't...

No. Do you want to know how a comparison of a naturally aspirated engine to a supercharged or turbocharged engine is fair? It's fair because that's the way they left the factory, and you can go right out and buy one of each and run them head to head. That's as fair as it gets in the real world.

You can't convert one to naturally aspirated operation or the other to forced induction, because you're no longer comparing the two engines. You're comparing a modified version of one engine to a stock version of another, and you're handicapping the one that was modified because it wasn't designed to operate that way. If you have to totally redesign or modify one engine to make the comparison "fair", what's the point? You're no longer comparing the two original engines, are you? Therefore, is any conclusion you reach really going to be valid?

Let's take the Mustang Cobra's supercharged 4.6L and compare it to the Z06 Corvette's naturally aspirated "5.7L". Fair comparison? Yes, you can buy one of each. They exist, we're not making up any fantasy rules to favor one or the other. Is it fair that the Cobra engines make more than their rated power? Sure. The LS6 engines do, too. See how unfair the comparison is already? Even the manufacturers don't play fair.

So let's say the Mustang Cobra beats the Z06 in a 1/4 mile race. Is that a fair comparison? Well, if you had a number of runs to form an average, but in reality, "fair" really depends on which car won, doesn't it? Or more accurately, on which car lost. If the Z06 lost (using ZeroBanger's mentality), the owner might say that it wasn't fair because the Cobra was supercharged. Well, if he wanted a supercharged engine, shouldn't he have bought one? If the Cobra owner lost, he might say that it wasn't fair because the Z06 weighs less. Well, if he wanted a lighter car, shouldn't he have bought one? The excuses for losing are practically endless, but you'll notice that the winner never has to make excuses for why they won... something to think about.

The bottom line is that the definition of "fair" is inextricably tied to the viewpoint of the one questioning it. Going back to my statement above that someone arguing for changes to make a "fair" comparison already knows that the real world comparison doesn't favor them, it would stand to reason that the person arguing for "fair" is someone who already knows they're the loser... and it's not human nature to be satisfied with that.

FDNewbie

iTrader: (10)

Jimlab...thanx a lot for the breakdown. Good stuff.

Question...the only thing that affects compression is the rotors? So NA rotors by definition give the engine lower compression, and rotors off the 13B-REW generate more compression? (yes I know the engine design must be compatible w/ the correct ports, intake, etc) But basically compression is dictated by the rotors? If so, what is the difference between the rotors that gives one higher compression over the other?

Very good point. Thanks for the clarification/explanation. I didn't see it from that prespective...only a theoretical prespective...

MazdaRx7Racer4Life

I think rotaries are awesome, infact, to be honest, the only reason I'd fight to the death for the 13b-rew is because its my engine, If my engine were a 20b Id fight fort it, just as if it were a renesis.

felix_is_alive

i would like to see the rennisis with lower compression and turbo
bye the way jim how long have you and zero banger been married,thank god you guys didnt have knives around (bye the way this is a joke )

tbonerx7

This sounds like a bar fight between two hicks ... "Fuel injection"!!! "Carburetors"!!!

Time will tell the truth about the Renesis. When/If they have forced induction on it from the factory, we will tell what's better. It comes with a warranty! Does that make it better

The rotary hasn't had much R&D as it should have. A team of samuri has dwindled to 10 or so engineers. That's pathetic. Now do you wonder why we're so far behind piston engines that have decades or R&D? LS1 is an awesome engine. Pneumatic valved engines are pretty damn awesome (V10 Honda still sounds great).

The rotary had its hey-day back in the 80's and early 90's. Mazda really needs competition to develope the rotary. Mazda alone cannot create the market for the engine as it once did (60's--rotary, the engine of the future). Today, we're not dealing with Corvairs and we are dealing with Ralph Nadir (sp?).

Comparing the Renesis and 13B-REW is like comparing apples to squash. Similar, but not quite. If there is a factory forced induced Renesis, that may be a different.

Hell, if the Renesis had the 13B-REW's power curve, I'd drive that any day.

Last thing about the Renesis... they stuck a 3-rotor turbo engine for a drag car in it... and they've been doing that on the FD,FC,FB,SA for ages (well, at least their shells).

Forced induction, 3 rotors, high revs... Good power there!
Then again, if you compare other engines... 10 cycliners, 5+liters of displacement, high rev, all aluminum with rare metals... yeah, good power there too.

Pros and cons? Sure. You could: like 'em both , neither, either one, or don't know. Some of the rotary's strengths are NOT as strong as they use to be... especially considering people are shoehorning LS1's in FD's without really compromising the chasis dynamics too much. That's incredible development for pistons.

What if's? What if GM put a rotary in the Corvair and Ralph Nadair was never born?! What if the English never made it across the Atlantic? All hypothetical now.

By some people's deductions and implications, I should be wearing wooden shoes.

saxyman990

Basically, yes, the rotors are what define the compression in a rotary engine. But you have it backwards: N/A rotors have HIGHER compression than the 13b-REW rotors. When you add forced induction to an engine, you generally need to decrease the compression ratio to account for the extra pressure. Basically, the main differences in the rotors that effect compression are the size and shape of the "cups" on the rotor faces.

Rob

FDNewbie

iTrader: (10)

Rob...thanks for the info. Now you got me all curious as to how the shape itself affects the compression haha

But that's prob gonna be a self-research project...and I'm sure it involves a lot of physics...

Oh and congrats
<< Congratulate me on my new purchase: 1985 RX-7 S. Currently in my garage being prepped for ITA7 racing >>

maxpesce

Actually the 13bREW runs 9:1 compression just like the S-4/5 NA's @ S-5 Turbos, only the S-4 Turbos ran the "Low Compression" rotors iirc.

The Renesis produces so much NA HP (albiet at High RPM) because it saggregrate port area (both Intake and Exhaust) is MUCH GREATER than even the 13B-re (Cosmo) that had the largest stock ports of all the 13B series untill the Renesis (which BTW is still concidered a 13b by Mazda becayse the rotor width and gernerating radius has not changed). iirc The Renesis exhaust port area is 1.5 times the -rew's

it is the Shape and Depth of the "BATHTUB" combustion chamber in the side of the rotor that determens the compression ratio. the smaller/less volume of the chamber the higher the compression ratio.

novadan67

Wow, what a thread this has become. I can agree with both sides of this argument. Is the Renisis a better engine than the 13B-REW if it were NA? I think that very few would argue that it is not. Even *if* the 13B-REW were designed to operate NA, it would still likely fall short of the Renisis - but probably not by that much. Rotaries are not rocket science.

I totally agree with Jim though - WHO CARES? The 13B-REW was designed for forced induction and with its forced induction it makes more power than the Renisis. Period. Now if Mazda were to go and redesign the Renisis for forced induction, I have little doubt that they could put down more HP than the 13B-REW (common sense). The fact is that they did not. Why? Most likely they want to prove that the rotary can be reliable.

There is also a pretty big flaw in Zero's 1/4 mile arguement. The RX8 and the FD chassis are very different. Putting equal hp engines in both chassis will certainly produce different 1/4 mile times (my years of drag racing experience has proven this). Threfore trying to argue that since the FD and RX8 in his arguement are nearly equal in 1/4 mile time does not prove that the engines produce similar hp numbers. There are too many variables involved. The only real comparison of ENGINE hp is the ENGINE dyno.

saxyman990

Yeah, that's true. I knew that, so I don't know why I was thinking the FD used lower compression rotors in my last post. But still, the basics of my post still stand.

Yeah, that's what I said.

saxyman990

Thanks! Just finished welding in the rollcage yesterday, and now I'm ripping apart the suspension. Should be track ready within the next couple of weeks.

Choser

What interests me is how the parts in the Ren. could possibly be used in some sort of frankenstein engine. The honda guys have had great results using bits and pieces of different engines.. who's to say that the stationary gearing, or the side housings, or whatever in the Ren. aren't good pieces of technology to use?

I feel like the reason Mazda didn't go FI in the rx8 is twofold. One for engine reliability, the other for market demand. The sports car market just isn't the same now as it was. Still, I feel like the Renesis is a more technologically advanced engine, but as to how much, that's up in the air. While you can't compare it to a na 13b-rew, it's much better performance wise than the na 13b before it, and I think that a FI version of the Renesis would be at least 300HP, were Mazda to produce one.

I don't know all the changes done to the Renesis but the main difference seems to be the exhaust ports on the side housing. If that change was so simple, I wonder why they didn't consider it earlier (they probably did...)

Crazy_Jake

Damn, and to think I started this thread about the RX-8 tranny bolting on an FD!

HEns

yes, that said crazy jake, im pretty sure there is a few 6 speed rx7s around, thought im not sure what boxes they are running

maxpesce

fwiw Renesis ROTORS w/ their higher compression combustion chambers can be used w/ s4/5 housings
however to do so I think you have to use the renesis, e- shaft, bearings and stationary gears also.

ZeroBanger

wow just got back from LA and this thread is getting better and better.

JimLab your argument is stupid. I dont care what you say, but comparing a n/a renesis to a turbocharged 13B-REW is stupid. The actual engine output of the renesis is higher.

you are really a dork.