sohc ninja

im thinking of buying a non turbo rx-7 but im wondering if its hard to rebuild the motor. would it basically be like a regular motor except there are no pistons? i dont know sheit..let me know guys.

kungfuroy

iTrader: (6)

'Hard' is some you can define yourself. Go download the free FSM and read the parts that describe, tearing down the motor, spec-ing the motor parts, and rebuilding the motor. Decide for yourself, if you can do it yourself and do it correctly without taking any shortcuts.
For my first rotary rebuild, I thought it was pretty easy. but I'd like to think I'm mechanically inclined, I followed the FSM and Haynes Manual, I have proper tools, and I spent money. Also I took my time to do it proper, I started my rebuild Dec' 2004 and just recently finished.

TitosToy

also you should get the atkins rebuild video. helped me alot

Spoolerr

Yeah, rotarys arnt difficult to rebuild, then again if you've never done this sort of thing i would research it more before you yank your engine out and start to loosen bolts....

KompressorLOgic

iTrader: (6)

its not that hard if u can learn how to rebuild a piston motor then u can do a rotary for sure,

there are write ups on it , and videos you can purchase that show step by step process

Aaron Cake

iTrader: (1)

Take a look at my rebuild thread in the Archives. Should give you a good idea on what's involved. Keep in mind that this thread skips all the measuring and prep work, and just shows the assembly.

carlrx788

If you have the space, the tools and time, do it, other wise it is hard, I am still trying to finish my TII I started on June. If your are mechanically inclined and this car is not going to be your only car for a while, do it, is fun
carl

piscorpio

I've wanted to rebuild an engine for a long time. With rotaries, is there alot of machining involved in a rebuild? I know for a piston engine, you need to at least hone the cylinders, maybe bore them out some.

Just wondering, because if it is just a matter of putting it together properly, I'd love to do it. If I have to get a lot of machining done, it gets expensive, and Im not sure who would work on rotaries.

rick_tj

No! Very little machining, if any. I believe that typically new rotors and housings need to be purchased. For the irons, I believe you can ship them out and have them surfaced machined, if the surface is quite rough.

homebrewer

Its easy to rebuild a rotary. There is a teenager on this website who has rebuilt his engine 4 times. The issue is whether you have the skills and patience to do it right.

johnnyg

I found it not difficult to dissassemble and measure all the parts, but never got around to actually rebuilding it since I happened by a used engine with low miles. One piece of advice - you can pretty much forget about setting a budget. The list of parts you NEED is pretty well known, but the list of parts you'll find you SHOULD replace is a different matter entirely.

westler91

It depends on how many miles that engine has and other slight factors as others have said. You can go on Ebay and get a JDM engine w/less than 40,000 miles for around 900 bucks. Rebuilding that one to the max would be wiser than rebuilding an old one laying around in a junker for a few yers

Aaron Cake

iTrader: (1)

Ever think that tehre's a reason he has had to rebuild his engine 4 times? The issues is having the skills to do it right.

As for machining, normally there isn't much or any involved. Used housings, if good, are used as is. Plates are sometimes lapped, but most of the time not. There is some clearancing, but that's just done with sandpaper and feeler gauges.

gxlbiscuit

easier than a stupid piston engine..... i cant wait to get married with kids ao i can stuff a rotary into a minivan... im not touching anything with pistons unless is says M-power

homebrewer

Aaron, I was trying to be more subtle and less obvious and not outwardly slam Felix who has had a bad run with his engines.

homebrewer

Why would anyone want to stuff a rotary in a minivan? You wouldn't have enough torque to get it moving down a steep hill.

Rotaries are more of a novelty engine with little, if any, advantage over a piston engine.

In fact, as I type this, I can't think of a single advantage over a piston engine.

Rotary engine

Cons:
1. Not fuel efficient
2. Not environmentally friendly due to oil injection requirement.
3. No low end torque and most power is developed at high engine speeds
4. Won't tolerate detonation
5. Engine failure rate is greater than piston engine
6. Have problems with flooding and carbon buildup that could get your temporarily stranded.
7. Not tolerant of being overheated slightly.
8. Fuel dilution is common on all rotaries to include RX8 negating any chance of extended oil change intervals with synthetic oils.
9. High exhaust temps rule out cheap exhausts and mufflers. No midas shops for replacement exhausts.


Pros:
1. The only pro I could think of was that they have less moving parts and can be easier to rebuild than a piston engine. However, if the rotary were reliable, who would really give a damn how difficult a rebuild was.

Robbierx7

iTrader: (1)

a new dvd is out that explains how to rebuild a 13b..they have other dvd`s available that show you how to rebuild a 20b and coming soon is a guide to building a 26b 4 rotor engine. my rx7 club in the uk has done a group buy for the 13b rebuild dvd, it will be with me in a few weeks.

the web site is http://www.diy-re.co.nz/

iceblue

[QUOTE=homebrewer]
1. Not fuel efficient
True
2. Not environmentally friendly due to oil injection requirement.
Who cares
3. No low end torque and most power is developed at high engine speeds
Not entierly true. TQ is quit comparable in stock turbo forms more so, only after heavy modings do the HP to TQ ratios spred apart to a noticeable difference and then again the yare high enough not to worry about it.
4. Won't tolerate detonation
I will agree
5. Engine failure rate is greater than piston engine
I highly doubt that and ever consider most of us run the **** out of them.
6. Have problems with flooding and carbon buildup that could get your temporarily stranded.
Not a properly running one.
7. Not tolerant of being overheated slightly.
Ever overheat a recipicating engine before? This is not accurate
8. Fuel dilution is common on all rotaries to include RX8 negating any chance of extended oil change intervals with synthetic oils.
My FE's fuel dilution is not even near the point of bad. All motors dilute some. Try replacing your side seals.
9. High exhaust temps rule out cheap exhausts and mufflers. No Midas shops for replacement exhausts.
True but why would anyone that takes care of a car use Midas or cheep parts of the such?


As far as Dustin’s string of bad motor luck I dunno what to blame it on. Maybe its the fact of building the motor in a bucket instead of a stand. Why b/c everyone on know that has build one on a bucket has torn in down in less then a week. Why would that be :-/ I will leave hat for everyone to argue.

Tournapart

iTrader: (4)

Most, not all, but most that own rotaries own them to modify them. take any piston engine and modify it, it will kill the life of the engine just like modding a rotary.
I drive my car fairly hard. ive own several piston engined cars and found that rotaries take to a beating alot easier simply due to the fact of less moving parts.

NO ONE said that these cars were ever produced to get good gas mileage, are at all good commuters or were supposed to be DD, even though mine is and it runs great.

Your car is what you make of it, and how you treat it determines the life and condition of it, this is true with any car rotary or not.

If it were so true that rotaries didnt last long then there would be no one with original engines with 200K+ on them, and yes ive seen quite a few.

The truth is, is that most ppl with RX7's tend to drive a bit more aggressively(sp?) than some one with a commuter car or a hybrid.

Although RX7's arent the fastest cars stock, they handle like butter and thats why i think they're great, and they're arent too many piston engined cars with a 50/50 weight ratio

ddub

I think he was more making the point that it may not have been the best example? Not sure. Just because people DO it on this site, doesn't mean they do it RIGHT. This isn't about Felix, but a big majority on this site.

How many times do you see threads like "I recently rebuilt my motor and it wont start" or "the motor I rebuilt 3k miles ago has a blown coolant seal/terrible compression/smoking/etc."

The problem is that too many people say it's extremely easy and go into it without doing the best job they could. Yes building a rotary isn't very difficult, but building a rotary properly is another story. Most people don't clearance and measure parts, unfortunately, and this is why many of them later have issues.

I've learned myself, do it once and do it right. No half-assing it like most people on here do. If you're going to build yourself a motor, do it right so it wont have to be redone later. Again not a shot at felix as it's a shot to many people on this site, since the trend is very similar.

homebrewer

My counter argument:

1. Not fuel efficient
True


2. Not environmentally friendly due to oil injection requirement.
Who cares

My response: The EPA does and let's be honest emission regulations will only get more stringent in the future. I don't care how many advances there are in metallurgy, you can't completely eliminate the need for oil injection. Look at the RX8 motor, its oil injection requirements are virtually half of our older rotary engines. I wonder how that will effect longevity. This was purely an emission driven requirement and probably done because 1/2 of the retards driving a RX8 would never check the oil.

3. No low end torque and most power is developed at high engine speeds
Not entierly true. TQ is quit comparable in stock turbo forms more so, only after heavy modings do the HP to TQ ratios spred apart to a noticeable difference and then again the yare high enough not to worry about it.

My response: I was comparing NA rotary to NA piston. I agree with you that turboing a rotary would greatly improve low end torque. However, is the cost worth it reliability wise? It doesn't appear that forced induction rotaries do to well when driven hard.
4. Won't tolerate detonation
I will agree

5. Engine failure rate is greater than piston engine
I highly doubt that and ever consider most of us run the **** out of them.

My response: I post on several car forums and by far this one has the greated amount of blown engine threads. Now, I have personally never had this problem with any of my NA's that I have owned over the past 18 or so years. I have never owned a turbo rotary though. I do drive all of my cars hard and on my newest turbocharged piston car, I have regularly exceeded the redline during the last 30k miles.


6. Have problems with flooding and carbon buildup that could get your temporarily stranded.

Not a properly running one.

My response: Partially disagree, a brand new RX8 has a high risk of floodingif you start it to move it out of the driveway and shut it off. Yes, flooding is unique to rotaries and can be avoided if the engine is warmed up before shutting it down or if you rev it to 3,000 rpm and when shutting engine off, press accelerator to floor.

7. Not tolerant of being overheated slightly.
Ever overheat a recipicating engine before? This is not accurate

My response: I have had failed cooling parts on several piston engines and never blew a head gasket.
I'll start with a small selection of the 24 or so piston cars I had a bad cooling/overheating experience with:

1971 International Scout. Blown radiator while cruising up a mountain pass.
1975 Ford LTD: Blown radiator
1984 Renault: Defective thermostatic switch
1994 Pontiac Sunbird: Cracked thermostat housing

Given the high heat output of the rotary it is less tolerant of overheating than a piston engine.

All of these enignes had gone into the "red" and all survived.

8. Fuel dilution is common on all rotaries to include RX8 negating any chance of extended oil change intervals with synthetic oils.

My FE's fuel dilution is not even near the point of bad. All motors dilute some. Try replacing your side seals.

My response: I didn't say I had a fuel dilution problem or worn side seals. What I'm saying is that if you readup on available oil analyis postings you'll see that this is an inherent issue with rotaries. It is a nature of the engine since they are tuned rather rich in stock form. Yes, all motors dilute some and I have slightly less than .5% dilution on my current new piston ride after a 10,000 mile oil change interval. However, rotary engines dilute fuel more than a piston engine and this often limits the oil's life.

Look at the following oil analysis resultsand you'll see people hitting 1.3% fuel dilution after 3-4k miles. Some of these samples showed a significant reduction in viscosity as a result of the fuel dilution.

http://theoildrop.server101.com/ubb/...=002863#000000

http://theoildrop.server101.com/cgi/...c;f=3;t=002659

http://theoildrop.server101.com/cgi/...c;f=3;t=002375



9. High exhaust temps rule out cheap exhausts and mufflers. No Midas shops for replacement exhausts.
True but why would anyone that takes care of a car use Midas or cheep parts of the such?

My response: Because not everyone has over a 1,000 dollars to spend on an exhaust for a 13+ year old car. Midas exhausts have worked flawlessly for me on all of my piston engine cars in the past and it is sure nice to have a few extra dollars in your pocket. The fact is that rotary engines are hard on exhaust parts necessitating premium parts that cost extra money. This is a fact that you do not dispute but instead avoid addressing by slamming cheap muffler places.

cool_as_crap

so...are you arguing with yourself?

Sideways7

iTrader: (7)

Both of the minivans my parents owned had 4-bangers with crappy low end torque, and they worked fine.

iceblue

[QUOTE=homebrewer]My counter argument:

My response: The EPA does and let's be honest emission regulations will only get more stringent in the future. I don't care how many advances there are in metallurgy, you can't completely eliminate the need for oil injection. Look at the RX8 motor, its oil injection requirements are virtually half of our older rotary engines. I wonder how that will effect longevity. This was purely an emission driven requirement and probably done because 1/2 of the retards driving a RX8 would never check the oil.

Exactly no one that drives a rotary ;-)

My response: I was comparing NA rotary to NA piston. I agree with you that turboing a rotary would greatly improve low end torque. However, is the cost worth it reliability wise? It doesn't appear that forced induction rotaries do to well when driven hard.

Reliability is not an issue in stock form remember we mod the **** out of them. There is several people in the past on here with well over 140k on a TII

My response: I post on several car forums and by far this one has the greated amount of blown engine threads. Now, I have personally never had this problem with any of my NA's that I have owned over the past 18 or so years. I have never owned a turbo rotary though. I do drive all of my cars hard and on my newest turbocharged piston car, I have regularly exceeded the redline during the last 30k miles.

You are nit picking from a group of tuners first time builders and kids that happen to purchase a 16yr old car and expect to b able to beat the **** out of it.


My response: Partially disagree, a brand new RX8 has a high risk of floodingif you start it to move it out of the driveway and shut it off. Yes, flooding is unique to rotaries and can be avoided if the engine is warmed up before shutting it down or if you rev it to 3,000 rpm and when shutting engine off, press accelerator to floor.

This is totally inaccurate! I actually own a FE as well does dDub I have moved mine across my driveway countless times and all sorts of other bad rotary practice and believe it wont flood. Why b/c the computer addresses the timing on cranking for exactly this reason. As well the FE uses bettor-atomizing injectors. As well as the accel to the flood comment would only be true on cranking for S5’s.


My response: I have had failed cooling parts on several piston engines and never blew a head gasket.
I'll start with a small selection of the 24 or so piston cars I had a bad cooling/overheating experience with:

1971 International Scout. Blown radiator while cruising up a mountain pass.
1975 Ford LTD: Blown radiator
1984 Renault: Defective thermostatic switch
1994 Pontiac Sunbird: Cracked thermostat housing

Given the high heat output of the rotary it is less tolerant of overheating than a piston engine.

All of these enignes had gone into the "red" and all survived.


This was a totally bogus statement and I think everyone could see that so I wont argue it.

My response: I didn't say I had a fuel dilution problem or worn side seals. What I'm saying is that if you readup on available oil analyis postings you'll see that this is an inherent issue with rotaries. It is a nature of the engine since they are tuned rather rich in stock form. Yes, all motors dilute some and I have slightly less than .5% dilution on my current new piston ride after a 10,000 mile oil change interval. However, rotary engines dilute fuel more than a piston engine and this often limits the oil's life.

Look at the following oil analysis resultsand you'll see people hitting 1.3% fuel dilution after 3-4k miles. Some of these samples showed a significant reduction in viscosity as a result of the fuel dilution.

http://theoildrop.server101.com/ubb/...=002863#000000

http://theoildrop.server101.com/cgi/...c;f=3;t=002659

http://theoildrop.server101.com/cgi/...c;f=3;t=002375

I do not even remotely see this as a issue even if a proper condition rotary did dilute this much b/c change your oil when you are suppose to and you will be fine.

My response: Because not everyone has over a 1,000 dollars to spend on an exhaust for a 13+ year old car. Midas exhausts have worked flawlessly for me on all of my piston engine cars in the past and it is sure nice to have a few extra dollars in your pocket. The fact is that rotary engines are hard on exhaust parts necessitating premium parts that cost extra money. This is a fact that you do not dispute but instead avoid addressing by slamming cheap muffler place.

Then you don’t need to be driving a sports car that is 16yrs old without understanding this upfront. This is a sports car and any recipicating sports cat exhaust is near to the same if not more then a rotary exhaust.

RotaryEvolution

iTrader: (30)

hard to build? no

hard to build right? yes