Hi /o/,
Quick question. My engine has a dual mass flywheel (DMF). I plan on doing some work on it, including moving the rev limiter upwards. Currently, the engine revs to 6500 before hitting the limiter.
Now I recall someone telling me it is not preferrable to rev a DMF beyond 6500 rpm. I didn't understand the logic behind that statement, and I can't find any supporting evidence for it. Is there any truth to it or can I raise the limiter to 6750/7000 without issues with the DMF?
>>14780587
just ditch the dmf m8, all that excess wieght and lack of reliablity are never a good thing, even in a standard car.
>>14780587
It's not bad, but the DMF is heavy, so it's won't be rev heavy, It also lets you keep better fuel economy by allowing the engine to hold momentum.
Also if you go to a light single flywheel your engine isn't going to shake. A lot.
>>14780590
I understand the logic behind your statement, but I haven't ever heard from any owners having trouble with the DMF, so I don't think it's likely to break down. When it does, I'll always have the choice to replace it with single mass. It'd be a bit of a waste of money to do it pre-amptively.
>>14780596
Any idea why this person would argue that DMF's shouldn't be revved over 6500?
>>14780590
I hate dmfs but be careful when replacing with a solid flywheel. It's possible to snap the crank due to different rotating mass, especially on diesels.
>>14780605
Because they are an idiot.
>>14780607
That's one way of looking at it, but it doesn't really explain the logic behind it. You can do better.
>>14780606
I'd rather not rev my engine above 6500 and keep my DMF than raise the limiter and replace it, it's not really worth the trouble if that's the case.
>>14780609
As a note, the SVT Focus red lines at 7200rpm and has a DMF.
There is no reason they can't be rev'd that high outside of the fat they are heavy.
>>14780620
That's some solid evidence, thanks anon. I'll go ahead and check if upping the limiter is possible.
>>14780627
What car is it? Chances are someone has already done similar mods before
>>14780587
it can probably rev a little higher than 6500 if you have strong intake and exhaust valve springs.
if not, your piston could hit the valves at high revs and fuck up your engine.
>>14780599
> I'll always have the choice to replace it with single mass. It'd be a bit of a waste of money to do it pre-amptively.
dunno man, when it seizes and takes out the clutch too you're pretty fucked. and they like to seize up. it might even be seized now, you're just too good at revmatching to notice.
>>14780627
For one the extra weight isnt a good thing at higher rpm's in case something does go wrong. Secondly it really depends on the design of the flywheel from the factory. 5.9 cummins were notorious for having atrocious dual mass flywheel issues, grenading, making noises all kinds of issues. Also the hyundai genesis is known for issues as well.
Would i per-emptively replace a DMF? probably not unless i had a hint of an issue beforehand. But i would also have in the back of my mind that every time i took the engine to 7k+ i was rolling the dice in one way or another.
>>14780627
what exactly are you attempting to achieve by gaining 5-600 rpm? if this is a hyundai genesis your not really doing yourself any favors as your torque curve is falling off pretty sharply past the 6500 mark unless you have additional mods done. There really isnt any good reason to raise the redline on any stock vehicle i can think of rather than just to say "i have a xxxx redline".
