Why do 8s need to be driven to redline?
05-20-2011, 06:32 PM
#1
Registered User
Thread Starter
Join Date: Apr 2011
Location: Iowa
Posts: 42
Likes: 0
Received 0 Likes
on
0 Posts
Why do 8s need to be driven to redline?
Okay, I'm probably showing my gender in this thread 
, but I have a question.
I've seen multiple threats/posts talking about the need to take the car out for a spin and shift at redline regularly for the health of the engine. This is my first rotary, and this perplexes me somewhat. I understand that this most likely is a quirk of the rotary, and from someone who has only driven piston engines, the question I have is simply:
Why?
Not that I'm opposed to doing this - it's a ton of fun and it's awesome to know not only is this kind of driving ok, that it's good for the car. I'm just curious as to why this needs to be done and what will happen if it isn't.
, but I have a question. I've seen multiple threats/posts talking about the need to take the car out for a spin and shift at redline regularly for the health of the engine. This is my first rotary, and this perplexes me somewhat. I understand that this most likely is a quirk of the rotary, and from someone who has only driven piston engines, the question I have is simply:
Why?
Not that I'm opposed to doing this - it's a ton of fun and it's awesome to know not only is this kind of driving ok, that it's good for the car. I'm just curious as to why this needs to be done and what will happen if it isn't.
05-20-2011, 06:37 PM
#3
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 240 Likes
on
110 Posts
I posted it in my new owner's thread earlier today actually: (https://www.rx8club.com/new-member-forum-197/new-potential-owners-start-here-202454/)
Every combustion engine out there generates deposits during the combustion cycle, and these deposits are carbon in nature. The same thing that Shell gasoline commercials or other fuel injector cleaner commercials talk about.
In piston engines, this is an annoyance only. Decreases the mileage and power of the engine a bit, but never really harmful.
In our rotary engines, it can be (and usually is) deadly to the engine, since it starts forcing seals out of place, reducing compression since the seals aren't holding right, which the hot gas blow-by starts wearing the seals and irons further, etc...
So it's important to keep the engine as free of carbon as possible. This is one of the justifications we give for full throttle acceleration to redline. It's fun , but it does also serve a purpose in helping to burn off that excess carbon. Our engines run much hotter than piston engines, so this is actually possible. This by itself will not keep the carbon clear however, so it is recommended to decarbonize (decarb) the engine occasionally. About once a year on a daily driver, but varies by how you drive, what type of driving, and how many miles. No real set rule on it.
Decarbing can be accomplished at a dealer for a crazy fee, or you can do it yourself with seafoam (Available at any autoparts store) for about $5, 5 minutes of work, and an hour or so of waiting.
In piston engines, this is an annoyance only. Decreases the mileage and power of the engine a bit, but never really harmful.
In our rotary engines, it can be (and usually is) deadly to the engine, since it starts forcing seals out of place, reducing compression since the seals aren't holding right, which the hot gas blow-by starts wearing the seals and irons further, etc...
So it's important to keep the engine as free of carbon as possible. This is one of the justifications we give for full throttle acceleration to redline. It's fun , but it does also serve a purpose in helping to burn off that excess carbon. Our engines run much hotter than piston engines, so this is actually possible. This by itself will not keep the carbon clear however, so it is recommended to decarbonize (decarb) the engine occasionally. About once a year on a daily driver, but varies by how you drive, what type of driving, and how many miles. No real set rule on it.
Decarbing can be accomplished at a dealer for a crazy fee, or you can do it yourself with seafoam (Available at any autoparts store) for about $5, 5 minutes of work, and an hour or so of waiting.
05-20-2011, 06:44 PM
#4
Registered User
Thread Starter
Join Date: Apr 2011
Location: Iowa
Posts: 42
Likes: 0
Received 0 Likes
on
0 Posts
Once again, great info. I love this forum! (I think I'm the only one in my house that does; the fam is getting a little tired of me talking about what new things I've learned about the car haha!)
And to be safe, I'm going to go get some of that seafoam.
And to be safe, I'm going to go get some of that seafoam.
05-20-2011, 07:04 PM
#6
Next step is for you to start tearing her apart and doing some work. Cleaning the SSV, installing oil cooler screens, checking the MAF, and even showing up one day with a vacuum tester to check valves before you seafoam her :P. Ah yes it could get real interesting in your house.
05-20-2011, 07:18 PM
#7
Registered User
Thread Starter
Join Date: Apr 2011
Location: Iowa
Posts: 42
Likes: 0
Received 0 Likes
on
0 Posts
Next step is for you to start tearing her apart and doing some work. Cleaning the SSV, installing oil cooler screens, checking the MAF, and even showing up one day with a vacuum tester to check valves before you seafoam her :P. Ah yes it could get real interesting in your house.
05-20-2011, 07:23 PM
#8
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 240 Likes
on
110 Posts
No, seafood is usually entirely before or entirely after. Unless you enjoy petroeum in your seafood, in which case I might point you to the gulf coast for some real deals!
For Seafoam*, no you don't
Just the next level of de-carbonizing maintenance is pulling apart your entire intake track and cleaning that as well.
I started out nervous about plug wires and coils a few years ago, and have progress to...well.... at the moment my 8' entire steering shaft and assembly (excluding the rack) is disassembled, getting the lower u-joint off for replacement. The only dealer quote I could find was $700. A $50 part from Mazmart and about 3 hours of work (most of it non-productive just trying to figure out how to do it) to get it off, and probably only an hour or two tomorrow to reassemble everything.
This car is REALLY easy to work on compared to other cars.
05-20-2011, 07:39 PM
#9
Registered User
Thread Starter
Join Date: Apr 2011
Location: Iowa
Posts: 42
Likes: 0
Received 0 Likes
on
0 Posts
I started out nervous about plug wires and coils a few years ago, and have progress to...well.... at the moment my 8' entire steering shaft and assembly (excluding the rack) is disassembled, getting the lower u-joint off for replacement. The only dealer quote I could find was $700. A $50 part from Mazmart and about 3 hours of work (most of it non-productive just trying to figure out how to do it) to get it off, and probably only an hour or two tomorrow to reassemble everything.
This car is REALLY easy to work on compared to other cars.
rotary
05-20-2011, 07:59 PM
#14
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 240 Likes
on
110 Posts
Actually, unless you are pulling and rebuilding the engine itself, there is no point in showing how complicated or simple one engine is to another
Ignoring the engine...the car itself, the rest of it. The suspension, accessories, maintenance items, etc... are what I was referring to. It really is VERY easy to work on. A few irritations, but not nearly as many as other cars have.
Ignoring the engine...the car itself, the rest of it. The suspension, accessories, maintenance items, etc... are what I was referring to. It really is VERY easy to work on. A few irritations, but not nearly as many as other cars have.
05-20-2011, 08:03 PM
#15
Registered User
Thread Starter
Join Date: Apr 2011
Location: Iowa
Posts: 42
Likes: 0
Received 0 Likes
on
0 Posts
05-20-2011, 08:07 PM
#17
Registered User
Thread Starter
Join Date: Apr 2011
Location: Iowa
Posts: 42
Likes: 0
Received 0 Likes
on
0 Posts
lol that's great!
My mom is thinking about selling her car before she needs to change the plugs because of how time-consuming it is...the intake manifold covers the plugs so it takes forever.
My mom is thinking about selling her car before she needs to change the plugs because of how time-consuming it is...the intake manifold covers the plugs so it takes forever.
05-20-2011, 08:32 PM
#18
Needz moar Mazdaspeed.
iTrader: (1)
Join Date: Apr 2010
Location: Mechanicsville, VA
Posts: 641
Likes: 0
Received 0 Likes
on
0 Posts
In the time it took me to replace the coils,plugs, and wires, and take PLENTY of pictures, and documentation to help prove I did do it properly to have the least amount of pain if I need an engine replaced under warranty, it took me hours less than it did to replace them in my mom's Taurus. Then again, I spent a LOT of time cussing out Ford for making it so difficult.
Though it's not as easy as the Mx6, where you can DIRECTLY reach everything from the top.
Ultimately though, rebuilding either engine isn't too bad. You could call me a mechanic, I'm not entirely the best, but when you break it down, everything's just remove a bolt, remove the part, replace the part, replace the bolt. Some things require more bolts and parts removed, but as long as you've got the tools to the job, and some instructions to go by, it's not that bad.
(I don't like doing things without instructions, at least to glance at. Especially for tightening things down, for the torque for everything. Besides, being complacent is where mistakes happen.)
But seriously, just think of everything as being as simple as that, and you're fine.
But on the topic of redlining it..
A redline a day keeps the carbon away.
So I wonder if you've got plenty of curvy, windy roads that you're attacking on a daily basis on your way to and from work... Hmm...
Though it's not as easy as the Mx6, where you can DIRECTLY reach everything from the top.
Ultimately though, rebuilding either engine isn't too bad. You could call me a mechanic, I'm not entirely the best, but when you break it down, everything's just remove a bolt, remove the part, replace the part, replace the bolt. Some things require more bolts and parts removed, but as long as you've got the tools to the job, and some instructions to go by, it's not that bad.
(I don't like doing things without instructions, at least to glance at. Especially for tightening things down, for the torque for everything. Besides, being complacent is where mistakes happen.)
But seriously, just think of everything as being as simple as that, and you're fine.
But on the topic of redlining it..
A redline a day keeps the carbon away.
So I wonder if you've got plenty of curvy, windy roads that you're attacking on a daily basis on your way to and from work... Hmm...
05-20-2011, 09:36 PM
#19
Registered User
Thread Starter
Join Date: Apr 2011
Location: Iowa
Posts: 42
Likes: 0
Received 0 Likes
on
0 Posts
05-21-2011, 01:04 AM
#22
I HATE SPEEDBUMPS!
Around 2 minutes or so? I'd rather ride my bike than driving my rx8. It may not even reach the normal driving temperature (specially on those very cold places).
05-21-2011, 02:45 AM
#23
Needz moar Mazdaspeed.
iTrader: (1)
Join Date: Apr 2010
Location: Mechanicsville, VA
Posts: 641
Likes: 0
Received 0 Likes
on
0 Posts
Definitely don't just drive it right down the street and shut it off. At LEAST let it sit and idle till it's fully warmed up, to heat it all up some. That's better than getting in, going like a mile or two, and shutting it back off.
As far as revving it up and shutting it off, I dunno, the only time I personally did that(With a different Rx8 than mine, actually. It was the other one I was contemplating buying, just like mine, but with 90k instead of 30k mi), when I did that, it had the hardest time starting versus every other time I tried starting it.(I took it on multiple test drives.)
Edit- Oh hey, I just noticed it's you again, haha.
Last edited by MS Addict; 05-21-2011 at 02:49 AM.
05-21-2011, 04:03 AM
#24
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 240 Likes
on
110 Posts
And that is if you HAVE to shut off the car bone cold. Go ahead and bring the revs up to 3k, then release the throttle and turn off the car quickly. It is somewhat effective in limiting the amount of excess cold fuel.
If the engine is warm though, there is zero benefit to do this, and some reason not to.