Fung

I have read lots of post saying that redline maybe once a day is good for decarb, but I am worried that cops will appear all of a sudden ._. (cuz of my bad experience)

So, my question is "Redlining your engine in neutral will help/not decarb?"

Thanks

elle

I'm not an expert at all(lol, just bought 1st rx8 yesterday)...but I think you may have to drive it to clear out the carbon, I've been reading this forum lots & I think I may have read that somewhere.

You can still go the speed limit & redline it. I do it all the time, it's easy when you are getting on the highway.

bse50

A red line isn't a redline. Engine load comes to mind...
Anyway redlining doesn't do much except preventing the intake valves from sticking. The only way to clean an engine through high rpm driving is on a track, after sustained rpm use and high engine load changes.
That will clean it! Otherwise just stick to good burning oils, premix and be done with it.

HiFlite999

iTrader: (2)

CW is that in-neutral redlining is a bad idea. Combustion chamber pressure helps hold the apex seals in place and is minimal with no load on the engine.

Shinka_MJR

cooling becomes an issue as well if you just sit in neutral and run up the engine. Dont believe me? sit in neut and hold at a higher rpm (doesnt need to be redline, 6.5k works) even for minute. your radiator light will come on, telling you that you're being a fuktard to your car and stop doing that or pay the consequences.

bse50

the radiator light is not about temperature.

jasonrxeight

you need a good engine load and a lot of air going into it. WOT in 2nd on ramp should do it.

40w8

The idea for redline to burn off carbon really means to drive to redline for a few minutes through all the gears, then, the heat load builds up to burn out the carbon.

Don't want to attract cops?

Accelerate hard onto entrance ramp, stay in 2nd gear, pass a car or two at full throttle up to redline, but don't shift, just slow down some, then shift after about 10 seconds.

Or look for a steep hill, and you can put heat and rpm on it for a minute or so without going too fast.

The best way not to attract cops is make sure you have quiet stock muffler.

Loki

iTrader: (1)

You don't need to redline, you need to do sustained full-throttle (which usually gets you to redline quickly). Pressure and heat clear our carbon, not how fast the engine is turning. On-ramp, 2nd gear, foot down to the floor. I usually do it in 3rd, you get a bit more above the speed limit than usual, but it's a nice sustained climb through the rpm.

pistonhater

wow, lots of misinformation around this thread.

There is no empirical data or research that shows red-lining your 8 will clean your carbon deposits to the extend that it will prolong engine life and longevity.

But if you search for info, you'll find engine builders who noticed a significantly higher amount of carbon build up in early AT 4-port engines. Because the redline on the ATs is lower than the MT - especially the early ATs - engine builders made the correlation between not pushing the engine enough and carbon build up - which led to engine failure in those engines.

But that doesn't mean that red-lining will certainly increase engine life. Many people are meticulous about it and still got engine longevity issues.

Ask '9rpm' about it. He has made that point several times as he went through three different engines even with meticulous maintenance and red-lining.

Mazurfer

Absolutely right............no empirical data that I know of, but I still climb through 2nd and 3rd to redline about once or twice a day, just because it's fun and makes me feel better(the placebo effect perhaps). Me personally, I NEVER redline in neutral or in 1st.

azzuro

heh, I always told myself "A redline a day keeps the carbon away". But how true is that really? Just go have fun and know that you're not actively damaging your engine if you hit the redline on an on ramp.

Socket7

I always cringe thinking about the first to second gear syncros trying to work at 9000 RPM. Second to third has always just felt better based off my highly sophisticated palm dyno (The butt dyno is useless for feeling your transmission shift gears. You gotta use a palm dyno).

jasonrxeight

why would it matter at 9000rpm? syncros dont get used when up shifting. its the downshifts that works the syncros.

Are-Ex-Eight

iTrader: (1)

I drive to redline when gas is cheap. It hasn't been often lately.

Socket7

If you're good enough and time everything exactly right, they won't get used ever. If you don't time everything right, the syncros wear instead of letting you grind your gears. They are used when up or down shifting.

I never said I'm being scientific here. First to second upshift is just the gear change that feels the worst to me. You have to let the revs drop a lot more between first and second, then between second and third, and so on. First to second just seems to be where you feel the syncros the most on your palm. Out of first, down past the neutral point, bump up against the syncros and feel it fall into gear. All the other shifts just seem to slide right into place slick as snot.

Like i said. I have a highly calibrated palm dyno.

Furthermore, first gear tops out at what? 35 mph? While making a catastrophic racket. I'd much rather get the shift up to second gear out of the way at lower RPMs. It's not like I'm drag racing anyone.

PeteInLongBeach

This just isn't true. Downshifts are harder on synchros (in general, unless rev matching and double clutching), but the synchros also get worked on upshifts as well. Just ask someone with dead 2nd gear synchros how their car upshifts....

Socket7

I imagine they have to hold the gearshift up against second for just a moment before it drops in.

Then the dogteeth begin to gnash.

If I'm really lucky I'll be able to blow out the clutch, engine, and tranny all at once and only have to pay for taking all that crap out once.

YUL PHL

iTrader: (1)

this. just did this this morning. slow cruise in 2nd gear @ 8.5k rpm for 10-15 seconds, then put it into 4th gear and kept going

bse50

^^^ That's useless and only wastes gas while building up heat.

RIWWP

iTrader: (2)

:facepalm:

"WOT" means "wide open throttle". You can't go WOT for 10-15 seconds while staying at a single RPM point. It means full throttle, pedal to the floor from ~3,000 rpm to redline, upshift to the next gear.

Sitting at 8.5k rpm in 2 gear does not have the LOAD you need, and is just overheating the coolant and transmission fluid.

If you have any way of monitoring MAF data, sitting at 8.5k rpm without accelerating is a fraction of the air flow you need. Something around 40g/s. Vs full throttle at that RPM is around 190-200g/s.

nycgps

iTrader: (1)

who is 9rpm? i know someone with a name like 9krpm something... but he sounds like some total noob who lives in the south all the time

well, i would say he got **** luck and reman engines aint that great in the first place, i have a reman engine and its still going strong... and there are people with original engine gompast 200k.


holy cow u got to redline higher than 3rd gear!?


redline to clean engine is just one of the thing, another thing is to clean and make sure ur valves arent sticking...

9krpmrx8

iTrader: (46)

The best way to keep a rotary carbon free is to pull off the heads and clean the intake and exhaust valves manually. You should also do a valve adjustment while you are in there and replace the head gaskets.

StealthTL

iTrader: (1)

There is no empirical data

I don't believe in empirical data - I just care for the theory.

"The empiricism of the empirical is a tautological tautology." - Alexei Sayle.

Hesselrode

iTrader: (3)

I did this last weekend and noticed a huge improvement on my acceleration. I think the carbon was clogging everything up. I would recommend others do this as well!! Gas mileage went up too!!

Hope everyone knows I was joking!!