RPM ...FLywheel...??

[trevork86]

I posted something about manual euro, when you're about to change gear, when you've already lift your foot from gas pedal, the rev will stay on and drop for approx 0.5 sec. Somebody told me it's because the DBW tech that helps to burn the resdidual fuel:confused:...
As i've seen in the forum somewhere, when people changed their flywheel, say lighter fly wheel, it will actuall improve the engine's respons to gas pedal, or clutch pedal..which i dunt know..

My question is, how do you actually improve engine's response when you lift your foot from gas? With rev stayed on, it is not easy to achieve smooth driving, and even when you wanna give a bit, the staying rev at high RPM just doesnt make sense....



Anyone help please..

[Type R Positive]

Heavier flywheel = more inertia. Takes longer for the engine to spin up and down.
Now if you have light weight flywheel, it will rev heaps quicker, slow down quicker, and actually make more power as it takes less power to turn the flywheel.

[trevork86]

Heavier flywheel = more inertia. Takes longer for the engine to spin up and down.
Now if you have light weight flywheel, it will rev heaps quicker, slow down quicker, and actually make more power as it takes less power to turn the flywheel.

You're a fast replyer!!! i truly appreciate that..

well, say, if i wanna go for a fly wheel
would it be better to go with a whole kit? like Exedy..

Or if i simply change my fly wheel, will there be any noticable difference??

How much labour cost would it be for changing a fly wheel?

[Type R Positive]

I'd go for the whole kit, it is expensive to change out the clutch/flywheel.
Aftermarket DC5 complete clutches fit.
There is a fiar bit of info on here if you search.

[trevork86]

Thanks... I will take a look..
I saw Suntzu's Mod Log. He got the EXEDY whole kit...

$$$$$ Sigh...i'll become a slave for my car..

[Type R Positive]

bare in mind that out of everything you can do for your car, clutch/flywheel is one of the best..... That and headers.

[tony1234]

You're a fast replyer!!! i truly appreciate that..

well, say, if i wanna go for a fly wheel
would it be better to go with a whole kit? like Exedy..

Or if i simply change my fly wheel, will there be any noticable difference??

How much labour cost would it be for changing a fly wheel?
PM aaronng here he's had a lightened flywheel and clutch installed.

[aaronng]

Labour is expensive. So do both the clutch and flywheel. Also, the Exedy lightweight flywheel comes only in DC5R size, so you will need the matching DC5R clutch to go with it. The only flywheels that matches the Euro's clutch size is the Fidanza and comptech (I think).

[JohnL]

On some cars (e.g. CB7 Accord among others), the IACV (or equivalent) not only adjusts idle speed when auxiliary loads are placed on the engine (AC, lights etc.), but also is used to hold the rpm up on the overrun with the throttle closed. This is for pollution control purposes, my understanding being that it reduces oxides of nitrogen.

An overun condition exists any time you lift off the throttle, say to change gears. This results in the rpm doing one of three things when changing gear:

Rpm falling more slowly than would otherwise be the case.

Rpm momentarily remaining at the rpm the engine was at when the throttle was closed, then dropping relatively slowly.

Rpm actually rising to some degree after the throttle is closed and the clutch pedal depressed, then dropping relatively slowly.

This results in engine behaviour that can cause poor gear shifts. The shift can be slow on the upshift and accompanied by a 'shove' in the back as the clutch is re-engaged (because the rpm is too high for the next higher gear). Downshifts involving rev matching can be more difficult to impossible to achieve smoothly because the engine's response to being 'blipped' can be a bit erratic.

If the rpm do not drop at all (momentarily) when shifting, then lightening the flywhel will have no affect until the IACV allows rpm to start falling (because the engine is still producing some power to keep the rpm at the higher level, and fly weight will have no affect one way or the other until power is cut). If the rpm do drop but slowly, then a lighter flywheel will probably help to some degree. If the rpm actually jump somewhat during shifts (which was the problem I had on my CB7, resistant to all attempts to cure other than my following method), then a lighter flywheel will in theory make this worse because rpm will jump more easily and to a greater degree due to the lighter rotating mass.

I finally 'fixed' the problem by blanking off the air passages into and out of the IACV. The downside of doing this is that the IACV can no longer adjust idle speed to account for auxilliary loads, but I found that setting the idle on the highest side of spec means that aux loaded idle rpm don't drop into the zone that causes excessive vibration (with AC etc operating).

Don't just disconnect the IACV electrical connector because this will cause a CEL, and make on / off throttle behaviour harsh in a way that blanking off the IACV ports doesn't (the computer doesn't like it). You could experimentally / temporarily disconnect the connector just to see if this cures your rpm problem.

After doing this to my car, gearchanging became a pleasure rather than a pain.

[trevork86]

JohnL,
This is magnificent.
BTW:

What i am experiencing right now is:

Rpm momentarily remaining at the rpm the engine was at when the throttle was closed, then dropping relatively slowly******* P.S. I can not justify whether it is slow or not, in comparison with my friend's Hyundai Getz, i'd say probably the same. But for the first point, it is definitely the case. It will remain at the rpm for about 0.3-0.5 sec.

About the IACV thing, is it the one which was structured inside the intake tube???
I've now idea... complete rookie

But thanks, your post is great~!!

[aaronng]

On the Euro, it is caused by the electronic throttle's programming in the ECU. They never fixed this for the Euro, but on cars like the Civic SI, the Hondata reflash actually gets rid of throttle overrun.

[Suntzu]

Hmm. I have the Jtune Hondata reflash which was done by Hondata.

it is the exact problem as described above that seroiusly pisses me off. The overun on downshift like the engines getting fuel off throttle.

So I have the jtune and am looking at getting a lightenflywheel and clutch to kill that biatch.

Hope it works as its an expensive gamble.

[trevork86]

Hmm. I have the Jtune Hondata reflash which was done by Hondata.

it is the exact problem as described above that seroiusly pisses me off. The overun on downshift like the engines getting fuel off throttle.

So I have the jtune and am looking at getting a lightenflywheel and clutch to kill that biatch.

Hope it works as its an expensive gamble.

Hope it will work!!! But as arrong said, i do agree that the problem is really likely to be in the ECU. But i do think change the clutch kit will definitely improve the situation. As in physics, the lighter the flywheel, the easier to change it 'state'...my english is bad and I'm trying hard on it..
Anyway saw the beautiful Exedy in your MOD LOG! Good on ya bro!! You will actually have a goJ while i can only put up with endless jealous...

just dont forget to post a review about it....

[aaronng]

The hondata reflash for the TSX and Euro didn't address this problem directly. The overrun is to burn off excess fuel. It is an emissions control "feature".

[aaronng]

Hope it will work!!! But as arrong said, i do agree that the problem is really likely to be in the ECU. But i do think change the clutch kit will definitely improve the situation. As in physics, the lighter the flywheel, the easier to change it 'state'...my english is bad and I'm trying hard on it..
Anyway saw the beautiful Exedy in your MOD LOG! Good on ya bro!! You will actually have a goJ while i can only put up with endless jealous...

just dont forget to post a review about it....

It is still there even with the lightweight flywheel. The difference is that the rpm falls quicker so this overrun is no longer a problem with having to wait to release the clutch at the right RPM.

[CL9R]

just had my ORC clutch with flywheel done 2day!!! Very good response on the throttle

[Suntzu]

How much did you pay for the install? Any clutch noise? Whats the feel of the orc ilke?