2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

why rotary engines are better?

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Old Feb 16, 2002 | 01:03 AM
  #26  
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Originally posted by DriftFC
Because rotory engines rarely last more than 90K miles... d'oh!
I've only had one with less than that, and the only two failures I've had (out of 9 engines) weren't the engines fault...
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Old Feb 16, 2002 | 01:05 AM
  #27  
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No energy wasted on those damn worthless exhaust strokes!
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Old Feb 16, 2002 | 01:32 AM
  #28  
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energy is still used for those exhaust strokes, its taken away from the combustion stroke that's occuring right next to it
BUT, it doesnt take an extra stroke like pistons, so it saves time and rpms
1 power stroke per revolution, that's the beauty of subary awd! err .. mazda rotary
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Old Feb 16, 2002 | 01:38 AM
  #29  
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that Turbo II I'm buying has 137k and on original engine
And N/As will last well over 200k on original engine. It's mainly turbos who have problems
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Old Feb 16, 2002 | 01:55 AM
  #30  
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Originally posted by mazdaspeed7


FWD, by its nature has a lower drivetrain losses from a simpler drivetrain. Most front engine, rwd cars lose 15-20% in the drivetrain, and Im sure some cars lose even more.
ah, i thought FWD cars lost more through their drivetrain? if this is true why are almost all sport and drag cars RWD? and yea i have heard the 15-20% through rwd cars alos.
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Old Feb 16, 2002 | 01:55 AM
  #31  
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From: Twin Cities, MN
Originally posted by DriftFC
Because rotory engines rarely last more than 90K miles... d'oh!
i hope this is a joke..
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Old Feb 16, 2002 | 02:07 AM
  #32  
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Ya.. The only way your not going to get over 90k is becaus hes either a chick or it wasnt driven more than once a month... I personely saw one engine at my mechanics garage with 177,000 miles on it and had good compression. Man I hate it when people make those ***-umptions. I was on the miata.net forum and people were telling me that my car will start losing power after 60k miles and I wont be happy when I need to replace the engine after like ..uuu I forgot but people are pretty much stupid about **** they dont know or not into.
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Old Feb 16, 2002 | 02:12 AM
  #33  
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Ok.. I have driven my rotory for awile and got used to it.... It was my first car... MY friend has a 97 miata with JR intake and exaust. I drove in it and the engine is seriously louder than his performance exaust. All I hear is tic tic tic tic...vrrroooooooomm ehhhrhrrrrrrrr rough rough buzzz buzzzz... I love miatas but this was the impression I got of piston engines. Try not driving your 7 for a month... Then come back and u will swere ur car hasnt had as much power as before and swere that U thought it was roughfer than this... U will tell yourself as I did... Man im never selling this car. Its ******* awsome.
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Old Feb 16, 2002 | 02:40 AM
  #34  
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Originally posted by von
Ok.. I have driven my rotory for awile and got used to it.... It was my first car... MY friend has a 97 miata with JR intake and exaust. I drove in it and the engine is seriously louder than his performance exaust. All I hear is tic tic tic tic...vrrroooooooomm ehhhrhrrrrrrrr rough rough buzzz buzzzz... I love miatas but this was the impression I got of piston engines. Try not driving your 7 for a month... Then come back and u will swere ur car hasnt had as much power as before and swere that U thought it was roughfer than this... U will tell yourself as I did... Man im never selling this car. Its ******* awsome.
ah, maybe i'm reading this wrong ( i have had about the equivalent to a 12 ack tonight ) but it says to me try not driving ur car for a month and then u swear it had more power when u drove it the last time and some other nonsense. no flammage intendin von. everytim i put it away or in storage and then bring it out, my 7 scares my and i don't remember it ever being thiss fast before. god i love doing it.....
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Old Feb 16, 2002 | 02:55 AM
  #35  
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Originally posted by supergoat


Um, that's not what I implied at all.

I just meant that the RX-7 seems to have a higher driveline loss than most other cars I've seen. I've seen a stock 88 non-turbo register 115 at the wheels. that's 20% loss. Same with the 89-91 registering 125. Also a 20% loss. That's higher than any stock other car I've seen dyno'd. I usually see 15-17%
young grasshopper you are obviously oblivious to THE FACT that different types of dyno's produce different readings, and there IS no precise way of being able to say how much HP is lost between the flywheel and the tarmac

take one rx7 making 400hp at the flywheel, put it on the typical US dyno and it'll churn out 340rwhp, but put it on the typical aussie dyno system and it'll churn out 292rwhp. are you gonna try and tell us that the car is loosing an extra 48HP in the length of time it takes to shift the car from one dyno to the next???????
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Old Feb 16, 2002 | 02:57 AM
  #36  
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Originally posted by Node
that Turbo II I'm buying has 137k and on original engine
And N/As will last well over 200k on original engine. It's mainly turbos who have problems
the main problem with rotary's are the previous owners of them!!!!!!!!!
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Old Feb 16, 2002 | 03:24 AM
  #37  
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Originally posted by supergoat


come on, we all know that ted is a rotyary god, and on top of that any car has a large loss in the driveline.

I'm really drunk right now, please don't remind me abou t tihis post, but ted is still a god.

Last edited by Mazdarules; Feb 16, 2002 at 03:31 AM.
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Old Feb 16, 2002 | 03:36 AM
  #38  
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Originally posted by HWO


young grasshopper you are obviously oblivious to THE FACT that different types of dyno's produce different readings, and there IS no precise way of being able to say how much HP is lost between the flywheel and the tarmac

take one rx7 making 400hp at the flywheel, put it on the typical US dyno and it'll churn out 340rwhp, but put it on the typical aussie dyno system and it'll churn out 292rwhp. are you gonna try and tell us that the car is loosing an extra 48HP in the length of time it takes to shift the car from one dyno to the next???????
Maybe it's because the water in the toilet in australia spins in the opposite direction than toilet watet in the states. Yeah that must be it.
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Old Feb 16, 2002 | 08:20 AM
  #39  
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Originally posted by BhamBill
I'm not knocking the rotary, but any engine can be rebuilt in a weekend if you know what you're doing. Ever watch them tear down an engine and "freshen" it in 45 minutes at the drag strip?
Have you ever seen them doing this "freshen up"? Its usually 10-15 people who are all trained and payed to do it as fast as possible, I couldn't imagine how fast it would taken them to FULLY rebuild a rotary, not just freshen it up
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Old Feb 16, 2002 | 08:42 AM
  #40  
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I have seen problems of not making it over 90,000 with the first of the 2mm apex motors. But c'mon let just not lump them all together and say they are going to die at 90,000. I know of to many examples of why that statement is WRONG!!!!
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Old Feb 16, 2002 | 09:36 AM
  #41  
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Originally posted by supergoat
I just meant that the RX-7 seems to have a higher driveline loss than most other cars I've seen. I've seen a stock 88 non-turbo register 115 at the wheels. that's 20% loss. Same with the 89-91 registering 125. Also a 20% loss. That's higher than any stock other car I've seen dyno'd. I usually see 15-17%
Yeah, drivetrain loss has nothing to do with the engine.&nbsp If you're talking internal engine friction, then you've got it all wrong.&nbsp Ever tried to park a rotary powered vehicle on a slight hill in gear without the parking brake?&nbsp Yes, it'll roll down the hill; this implies very little internal engine friction.&nbsp Try THAT with a piston engine!

Most FC's and FD's I've seen spit out about a 15% drivetrain loss on a DynoJet 128C.&nbsp I don't know what set-up you're referring to when you quote 20%, but 15% is typical of most RWD vehicles.&nbsp The lowest drivetrain loss I've seen on a rotary was an FD with all Redline fluids (MT-90 in the trans and 75W90NS in the rear diff) that spit out an incredible 12.5% drivetrain loss!



-Ted
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Old Feb 16, 2002 | 10:51 AM
  #42  
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A 1.3L rotary acts more like a 2.6L 4 cycle piston engine. An engine (piston or rotary) is basically a self driven pump. Therefore, every crankshaft rotation of a 2.6L piston engine "pumps" 1.3L of air/fuel. Every crankshaft rotation of a 1.3L rotary pumps 1.3L of air/fuel.
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Old Feb 16, 2002 | 11:05 AM
  #43  
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Originally posted by 1Revvin7


ah, i thought FWD cars lost more through their drivetrain? if this is true why are almost all sport and drag cars RWD? and yea i have heard the 15-20% through rwd cars alos.
Perhaps FWD loss could be a reason, but not the main one. Picture what happens when you floor it. The weight goes to the back. Friction increases with increased weight/force, so you're able to apply more power. For racing with corners, RWD is far more condusive, because it creates overstear. FWD creates understear and you miss your turn. I've always heard FWD was less efficeint as well.

Last edited by Snrub; Feb 16, 2002 at 11:08 AM.
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Old Feb 16, 2002 | 11:40 AM
  #44  
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this is an informative post
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Old Feb 16, 2002 | 01:51 PM
  #45  
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Old Feb 16, 2002 | 02:41 PM
  #46  
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Originally posted by Snrub


Perhaps FWD loss could be a reason, but not the main one. Picture what happens when you floor it. The weight goes to the back. Friction increases with increased weight/force, so you're able to apply more power. For racing with corners, RWD is far more condusive, because it creates overstear. FWD creates understear and you miss your turn. I've always heard FWD was less efficeint as well.
Exactly....I cant understand people dragging FWD cars....When you build a car strictly for drag if its FWD....then the only point is to try and break FWD records.....Cause when you slam your foot on anything in excess of 450 hp fwd you've got problems.....first you have all that weight lifting right off the tires....then that much power churning them, you'll be spinning into tomorrow (well, you'll lose a few good seconds)...the only way to get around it is through suspension mods and HUGE SLICKS...but then you run into another problem....with those huge tires and all that power slaming into all that friction....you crack fwd axels like there is no tomorrow. So yea FWD dont lose as much power through the drive train...but the extra power VS the consequences usually isnt worth it in my opinion.
I'll take my rotary with 9'' streeters on the rear, drive it to the track, and be damn glad its not fwd any day over the extra drivetrain power....
But as for understeer goes.....in circuits thats what the TYPE R integra was desgined for......One of the only production FWD cars you can get oversteer from...I think thats really cool...even though I dont like the typical integra nor its driver...I respect the type R
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Old Feb 16, 2002 | 04:37 PM
  #47  
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WOW, MikeL that's an awesome picture for comparison! The Rotary Engine is great, my only knock against them is that they consume more GAS then what they should with 1.3L displacement and also they can't withstand detonation as well as a piston engine.
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Old Feb 17, 2002 | 02:53 PM
  #48  
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Originally posted by MikeL
I know where you got that picture!! I know where you got that picture!!



Ren

Last edited by turboren; Feb 17, 2002 at 02:55 PM.
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Old Feb 17, 2002 | 03:01 PM
  #49  
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Originally posted by repuguru
I have seen problems of not making it over 90,000 with the first of the 2mm apex motors. But c'mon let just not lump them all together and say they are going to die at 90,000. I know of to many examples of why that statement is WRONG!!!!
Example: My first FC was an 86 base. I replaced the engine in it, not because the apex seals were shot, but because it was starting to get low on compression and somewhat hard to start when hot. I ended up replacing the replaced engine with the original when the replaced engine lost an apex seal (constant bouncing off redline in first gear on a autocross course = bad idea). Mileage on original engine when pulled: 230,000!

Ren

P.S. repuguru -- John Denver fan?
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Old Feb 17, 2002 | 03:22 PM
  #50  
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ah, i thought FWD cars lost more through their drivetrain? if this is true why are almost all sport and drag cars RWD? and yea i have heard the 15-20% through rwd cars alos.
Perhaps FWD loss could be a reason, but not the main one. Picture what happens when you floor it. The weight goes to the back. Friction increases with increased weight/force, so you're able to apply more power. For racing with corners, RWD is far more condusive, because it creates overstear. FWD creates understear and you miss your turn. I've always heard FWD was less efficeint as well.
True, FWD has lower drivetrain losses. The engine's power has fewer different parts to have to go through on its way to the ground. RWD has more losses, next AWD, and most losses is 4wd (switchable transfer cases).

RWD is usually best in drag races due to the power being put to the ground at the end of the car where most of the wieght is transferred. Prime example of good production-based drag cars are Porsche 911's and VW Beetles (original), because the engine and tranny are in the rear, thus adding to the available traction. FWD is the exact opposite, most of the weight is in the wrong end of the car, and to top that, you have the drive wheels at the end of the car from which most of the weight is being transferred.

The end of the car in which most of the weight resides also determines its steering characteristics, as does the drive end. FWD cars tend to understeer due to the weight in the nose of the car, complicated by the fact that the front wheels have to drive as well as steer. RWD cars tend to be somewhat more balanced in weight distribution, and the front wheels don't have the added load of having to drive the car. Most still tend to understeer initially, but can be made to oversteer based on throttle input. RWD with rear engines tend to oversteer naturally, because most of the weight is in the back, thus overloading the rear wheels in a turn. Mid-engine RWD cars tend to be neutral in steering nature, since the weight is almost dead even in distribution. AWD cars tend to understeer because the front wheels still have the drive load like FWD cars have.

Geez, this is getting too deep now. There are books available on this topic, which I highly recommend if you REALLY want to know about handling dynamics.

Sorry for the long post.

Ren
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