Don't waste your time with this guy. He's all knowing, even though he's never personally experienced driving an LS1 FD himself. I've never heard ANYONE who did the swap, complain about their handling getting worse. Even rotary owners have acknowledged when riding/driving LS1 FD's owned by someone else, that they can't tell a difference in turning or handling.

BTW, you can get LS series motors into the mid 1,000hp range. For cheaper than doing rotary. Hell, Ford has been doing it for years with Mustang engines. Once again, the guy is all talk, and no knowledge.

 

This is a concern, because I can get an ls1 out of any junkyard for cheap. This isn't the case with a 4 rotor. A 4 rotor isn't going to be light, and do more damage to your precious handling dynamics then an ls1 could. An ls1 and ls6 are almost the same engine, and both are outdated. I've never seen a 4-rotor engine that wasn't built for racing, maybe you shouldn't be comparing a race car engine with one thats designed to last 100k+ miles, get good gas mileage, use pump gas, meet emissions, and comply with NVH(noise, vibration, and harshness) standards, all while being as cheap as possible to manufacture. The engine in a C6.R is rated at 590hp/640tq, I'm sure this is not the limit of whats possible considering all the rules and restrictions behind it, and it only revs to 6000rpm. In the aftermarket world 600whp n/a ported heads/cam ls7s are starting to pop up, just a matter of time before aftermarket heads and intakes become available to bump these numbers even highter.

If rotary engines are so superior, surely you can find me some examples of 600whp n/a rotary engines that you could drive on a daily basis and are of comparable size and weight to these ls7s.

You bitch at me about reading comprehension and come up with that? I know the weight is above the crankshaft obviously, considering its almost the lowest point in the engine. I have a feeling you've never even seen an ls1 mounted in an rx7. The f-body oil pan is a rear sump, and the front sits right above the steering race, requiring it to be lowered in some cases. The fact of the matter is your still just going off speculation, when others have looked into the subject more deeply and found that the difference is almost insignificant.



Um, okay? Like it or not you still implied that I don't belong. And when you say THIS forum, I assume you mean this section. I don't see how the other technical forums wouldn't apply to me considering I do own an rx7.

I was "justifying" myself because you said....

"And what purpose do you serve?"

I was pointing out that I never claimed to serve any purpose beyond my own enjoyment of my car. You are one who claimed to be helping mazda do R&D by modding your car. If anything that you thought up and designed ends up on a new mazda sports car, I will eat my own shoe.

So you go on about how rotaries are so great and v8s will just screw everything up, but you refuse to even drive one? Can you say close minded? I haven't met Howard Coleman, but I know hes a smart guy and wouldn't discount a v8 powered rx7 from being a good handling car.

What kind of numbers would be meaningful to you? Skidpad? lap times? corner weights? They are all out there if you look.

 

Your preference of power out of a corner is your choice. Just don't assume that a 20b can't have torque coming out of a corner either. With the right turbo, boost would be instant and you could easily have access to 400+lbs in the mid range. You have never ridden in a boost 20b have you? With the extensive knowledge that I have of rotary engines, you could never convince me that a comparable piston engine is better ( performance wise ) when you fairly compare them by displacement. Is it fair to compare the a 2.4L Dodge Neon engine to a 5.7L V8? I wouldn't think so. Now as far my a 20b fd goes, you are completely wrong. My 20b is currently sitting lower than my 13b was. Also due to it's length, I have more weight closer to the center than what the stock fd has. I've already said before, it's where you put the weight. I have a lower center of gravity and lower polar moment while still maintain perfect balance. That means my car will respond quicker to steering wheel inputs since now most of the weight is around the vehicles center of rotation. This is what I mean about handling dynamics. How far could you push that V8 back? My alternator sits at the center of the front axle and my rack is in the stock location. So I don't have to worry about bump steer. I know (from what I've seen ) that V8 conversions sit well ahead of the front axel. By the way, I haven't cut my fire wall either. I will build my very own custom intake set-up from scratch. So yes I guess I'm very ignorant that I have this knowledge and ability to perform such task.

As far as the double standard issues, I agree with you but you are on a rotary forum. People will always be biased towards the rotary. You guys are no different when it comes to pistons. It goes both ways. We all think our engines are the best however, I'm not clueless to the reasons some of you choose to go with a different engine choice. That's your decision. What I can't stand (and why I even posted in this section) is all the negativity involved with people who blow these engines due to negligence and ignorance, then come on here to spew garbage about how unreliable rotary's are. For the people who understand them, rotarys are some of the most reliable engines in the performance category.

 

Dude I've been talking about 13b based 4 rotors potential as an engine. Not what it will do in my Rx7. The engine is too long to be properly placed into the engine bay without moving the rack or seriously modifying the fire wall. Also I never said I had one however, I do have future plans of putting one together. As far as weight, I can't say as I don't have the aluminum side plates that I would use to reduce the extra weight of the heavier motor. I hate the heavy side steel plates of rotarys'. To add a 4 rotor doesn't need boosting so you save weight from the lack of turbos and plumbing. My future plans for a 4 rotor involve a mid engine configuration. I will find some way to try and calculate the weight for you.

 

I don't need to have personal experience with LS1 conversions to see where all the weight is. If you have a true understanding of the science behind automotive engineering, then there's a very solid chance you can tell what happens when certain weights are moved to different locations. Handling differences will never be realized on the street driving around town. The difference is noticed at the vehicles limits.

 

LOL So a C6R race engine still has yet to match what the smaller displacment 4 rotor 787b was making (690 hp back) in 91? What's the hold up?


As I said before, 4 rotors are were mainly used as racing engines when introduced. It's only been recently that aftermarket shaft kits have been made available to the average public. So it's only a matter of time before you start to see them becoming more common place amongst the people who have the ability to build them. That doesn't mean they can't be set-up for day to day usage. Minus the the e-shaft, it's basic components are all 100% factory based parts that already exist. So there's no reason a 4 rotor can't be built for a road going car and last well over 100k.



No I did not. You still dont understand! Moving on!





Again you take everything to literally. How is me saying changing the handling "DYNAMICS" the same thing as me saying it will just screw everything up? You keep taking my comments to the extreme. By the way, Mazda's engineers engineered the Fd to be a great handler and not just good.

 

Do you think that fooled anyone?

Can you tell just by looking where the CoG of an F1 engine is? Were you aware that by F1 regulations, the CoG must be at least 165mm above the lower edge of the oil sump (pan), and that the longitudinal and lateral position of the CoG must be in the geometric center of the engine (+/- 50mm)? Now why do you think they'd have a rule specifically stating where the center of gravity of the engine must be if all the weight was just "at the top"?

Were you aware that only about 80 lbs. of a 460 lb. LS1 is above the camshaft centerline? Were you aware that the heaviest section of the block and the heaviest components of the engine are at the bottom of the block? Were you aware that at any given time, roughly half of the weight of the engine's rotating assembly is below the centerline of the crankshaft? Now, where is the CoG of an LS1?

Keep talking out of your ***. You're really good at it.

 

I'm not an expert on racing classes, and don't have the time or patients to look them up, but I can tell you that the C6R races in a GT class that is only for production based cars with limits for the power/weight/top speed where as the 787b is a full on race car. The 590hp/640tq wasn't meant to be a claim for the maximum the engine was capable of, but it would be a closer comparison for a p-ported and modified 4 rotor engine.

Again, since it hasn't seem to get through to you yet, I will reiterate that smaller displacement means nothing on its own. Sure your 4 rotor might be smaller displacement then an ls7, but if it gets 10mpg and weights over 500lbs its not going to be my top choice for an engine.


I will keep and eye out for these bigger rotary engines to start becoming more common, but my gut tells me they aren't going to be very impressive when setup for a street car meant to last well over 100K miles.


Nope, I guess I don't understand.

 

Wow, lots of energy here. It's personal choice, plain and simple. Throw the math books out and just do it, whatever that is that you do. If you've ever been married you should be used to others not understanding why you do the car stuff you do. I figure if the people that love you won't understand your love affair with whatever engine you have why the hell would we even begin to try.

 

The CoG of the engine is just a bullshit argument, for many reasons. The ENTIRE engine only adds 80 lbs or so to the car, and it sits lower than the hood line and nearly lower than your HUMAN center of mass when you're sitting in the car. And 80-100 lbs is, overall a mere FRACTION of the mass of the ENTIRE car w/driver, so the change, even if it WAS detrimental (which it isn't), would be negligable.

And NO ONE complains about the CoG changning when you add a ******* ROLL CAGE that adds 50-100 lbs or so HIGHER UP! But that seems to be a common addition to a road race car, so it must not hurt it THAT bad...

My car was an autocrosser BEFORE the conversion and an autocrosser AFTER the conversion. With no changes to the suspension other than a reworked front swaybar to clear the Ford oil pan, the car's balance was better, the turn in more precise, and the understeer slightly reduced from what it was before the conversion, due to the mass of the engine/trans sitting farther back in the chassis. This was noticeable in neutral-throttle conditions, where chassis setup and balance was the key, not the power. Plus, the ability to power out of low speed corners without shifting made it infinitely more tossable, with the same tires and suspension. I had been autocrossing successfully at that point for over a decade, and the car won it's class for the season in rotary form, so I think I have a basis for comparison.

http://mywebpages.comcast.net/adesso/rex3.wmv

t-von, your arguments are theoretical and mostly made up on the spot due to a woeful amount of ignorance of the swap and a pathetic quasi-religions love of your rotary. it's good to have favorites, but don't let that lead you to making up crap on the spot just to support a tenuous position.

(BTW, you still didn't comment on the reality of the *** .049 engine making over 400 hp/liter for very little money. If hp/liter is that important to you, why don't you use one to power your car? It would be "unique.")

 

This statement alone shows how little you truly know about "automotive engineering".

You seem to think that combustion efficiency is a constant and that if a smaller engine produces X horsepower per liter, then one that is much larger should be able to meet or exceed that, solely because it has more displacement.

What you fail to grasp is that for the same reason that the rotary engine's football-shaped combustion chamber is less efficient, the larger the diameter of a piston engine's bore, the less efficient it is at burning the fuel in the chamber. Increasing displacement increases torque, but it decreases combustion efficiency.

Conveniently, the bigger engine doesn't have to be as efficient as the smaller engine, because it will absolutely have a broader and more powerful torque curve, and that is what makes a car faster... not horsepower per liter.

 

This thread is hilarious.

/Subscribed.

 

Ok so.......
The 4 rotor cost a lot more than a V8.
Requires much more work to install.
Weighs more.
Makes less power stock for stock.

Yes, I'm starting to see your point, the 4 rotor seems like a much better engine choice.

 

It's nice you finally rejoined the conversation. Of all the points I made since you dissappered, this is the only thing you could find to challenge me with? F1 engine isn't a production based engine now is it? You guys aren't putting that engine into your 7 are you? Where you aware that all the 13brews weight is down their including the heavy turbo's? Lets not discount all the factory accessories too that sit really low. Plus everthing sits behind the front axel. If you think putting an Ls series V8 in the Fd engine bay doesn't put more weight away from the center of rotation then, you are a complete idiot.

Again 50/50 scales dont tell you were the weight is. Only the balance from front to rear. You can take a drivetrainless chassis and put 1000lbs at the very tip on opposite sides of the frame and have perfect balance. Does that mean you will get responsive handling? Nope. Does putting weight that far away from the center of rotation improve the handling dynamics or ease of change of direction? Nope. What happens when you move the 13b engine forward 6"? You effect the handling dynamics. Same thing with a 20b that's installed with the tranny in the stock location. Same thing happens with the v8 conversion if installed without moving it back. Why can't you guys understand that?

How much more ahead of the front axel does the LS1-6 sit? No need to guess, cause it's more forward than the 13rew.

 

Fair enough. Just to let you know 4 rotors wouldn't have to be modified much internally to reach those levels. Other than the P-ports, hi-compression rotors, balancing, and oil mods, internally these are the only things needed to have the potential to achieve these numbers NA. The intake and engine length are your main challange.




Key words are if! 500lbs? Here's some math for you. 13b block weighs 150lbs times 2 equal 300lbs. Actually it's less than that cause a 4rotor would be minus 1 heavy side plate (5 side plates and 4 rotor housings). Intake 30lbs! Header 30lbs. Also think of the weight savings if you build with aluminum side plates that do exist (though they are very very expensive )? The fuel economy? I'll leave that up to the custom intake I'm engineering for my 20b. I'm very confident my design will do much better than that.


Comments like these just fuel my desire to prove naysayers wrong. Thx for the boost.

Peace!

 

Very good point.

 

Thx you just proved my whole argument. I know it's negligable and always knew it was but it's still change. The roll cage is at the center of rotation. Other than the extra weight you get at the top, it wont effect the steering response only roll.





Great info. I was never speaking of V8 conversion in Fc's. They have more room in the engine bay, so I can only assume you would be able to move the engine lower and back to achieve your results. If this is what you did, then I applaud you for doing it right. The same can't be said for the Fd unless you do some major firewall surgery.

So now I'm making up stuff. Please [QUOTE] me on my previous comments.


Now your showing some ignorange. Give me a break the tiny masses of that little engine make that possible. I guess you think an ant will have the same strength if it was the size of an actual human?

 

I am when it comes to rotary's and how they make power. See post #91 Jim. I guess you missed that one? Now I don't understand why manufactures bore and stroke a piston engine when they need a hp bump. Rotary's dont need this to done. I mean why did Dodge need to upgrade the displacment of the Viper engine for 2008? Was that really neccessary? I ask cause I truely don't know.

Can't disagree with you here. That's why I like smaller turbos go give me more mid range than top end. If I had a 4 rotor, the only reason I would even turbo charge it is to boost the low to mid range and nothing more.

 

Yes!

Nope if you put the engine in the same location as stock and drop the rack then no cause this is exactly the same thing you will have to do to put the v8 in. You can't just sit the V8 in the stock sub-frame and close the hood.


See my above post to Rosey about the weight.

Trick question as the 4 rotor isn't stock.

 

Wait, if you install that motor in the stock location then it really won't turn.
My rack is right where mazda put it. So yes harder to install.


So your saying the 4 rotor is less than #300 ready to run? I'll beleave that when I see it.


Neither are most v8's when installed in a mazda.
Stock 13b ~150hp x2 = 300hp
300hp = less than a stock LS1
No trick in my math, looks like less power out of the 4 rotor.

 

Ok please enlighten me on your set-up.



That's not what I said. Go back and re-read. I said the block itself is less than 300 lbs (based on 2 13b weight's minus 1 side plate). I also included the intake and exhaust for an extra 60. Then of course you have accessories, alternator, power steering 30 lbs. So 390-410 is a fair guess. Now if you build with aluminum side plates, those (after research) are more than half the weight of the factory sides. Factory side plates weigh 26lbs. A comparable aluminum side plate weights 11lbs. So now you save 15lbs per plate. Times 5 saves you an additional 75 lbs. So an all aluminum 4 rotor ready to run could weigh 315-335. Even still it could weigh less than that since I used two 13b block weights (300lbs) as my starting point. I forgot to subtract the one side plate (that doesn't exist) therefore this should put the original block weight at around 275lbs or even 200lbs if it's all aluminum.


Easier breakdown

Stock block weight =275lbs
accessories 90-110lbs
Total =365-385lbs

All aluminum block = 200lbs
accessories 90-110lbs
Total =290-310lbs

Damn it may be possible



Uhhh on side ports 13b can achieve 240 hp or more. Please don't use stone age hp figures from back in the 80's. Nice trick. Double that for a 4 rotor and your sitting in the 480hp range. You fail to realize the rotary's true potential has always been with it's intake design and not adding displacement. The same displacement 13b has nearly doubled it's hp output since the mid 70's.

 

If pieces like AL side plates are game you've got to compare apples to apples. Ti rods, etc on the V8 too.

What is the length on your 4-rotor vs. V8?

I read a mag last night that had a LS1 w/cam and exhaust putting out 425hp or so. No other mods. LS2 pump out 430hp in street legal trim.

 

When I get home, I'll stack some plates together to get an idea but I know it's little longer than your average V8 or about the same length of a BMW straight 6. I see your point about the aftermarket parts, however I was just showing how light the block could potential be. LS series blocks are also aluminum. So it is apples to apples when you compare the block materials but at the same time it's not since aluminum plates aren't stock. I'm not trying to compare hp to weight based on engine weight. I was comparing hp by liter. Besides we don't have lighter internals we can use other than lightening the rotors.

FYI! Off subject! The new 16X rotary in the next Mazda sports car will have aluminum side plates (it's about freaking time) and a longer stroke for more torque over the entire rpm range. Finally we get a soo called big block rotary. Can't wait to see what it will do.

 

I'm curious what point should I of not missed?

I just see someone trying to **** people off with already known facts? I guess it worked on alot of people.

 

Doesn't matter. You claimed that just by looking, you could tell that an OHV LS1's CoG is "at the top", when an OHC F1 V8, with more mass at the top of the engine, can have a CoG so low that they actually have rules to regulate its location.

However, I can tell without looking that you're more dense "at the top"...

Doesn't matter, but thanks for trying to change the subject. You're still wrong.

Are you even functionally literate?

Right, like the alternator and power steering pump?

Were you referring to Axel Rose? Can't tell with your spelling mistakes.

If you think it makes a huge difference, then you're an even bigger dipshit that I originally thought.

Do you know what corner balancing is and why it's far more important than front/rear weight distribution?

Maybe you should look at some of the corner weight sheets posted by people who have weighed their LS1 cars instead of pulling more subjective bullshit out and flinging it at the screen, hoping some will stick...