Was: Lightened Flywheel -2.0l 16v, now turbo engine

[corylang at dccnet.com (Cory Langford)]

Actually, a lightened flywheel on a turbo is not the best idea.

What ends up happening most of the time, is your rev it up faster the turbo
spools up too fast, the waste gate opens to compensate and then you need to
shift.  The blow-off valve kicks in because when you shift most people take
their foot off the gas pedal - most any ways :) - and the closing of the TB
causes too much boost in the tubes (that is what the BOV is for of course).

By the time everything closes and your engine is seeing power making boost
again you have the same cycle over again.

You need to keep your engine in the correct rev area to keep boost up, but
you don't want a sudden boost spike and then sudden drop because it gets
lost before it gets into your engine. If it didn't the constant spikes
would cause a much higher chance of grenading your engine.


Now on a super charged engine it might be a different story.  They tend to
have a valve that lets off boost and the boost is based on directly on
engine rotation, so they might have a use for a lightened flywheel.  I have
to check into this for the mk2 2L G60.

But trust me on the turbo. I had to take it out of the '78 with the turbo
engine. I am much happier with the standard flywheel and a nice wide ratio
tranny to keep a long time between shifts.

Cory

At 10:47 AM 08/30/2004 -0400, Dan Bubb wrote:
>So, can you explain the rational behind what you were told?
>1st and 2nd would be useless because the engine revs faster so the turbo
will never spool???
> Like saying you should make your engine heavy and slow revving so it'll
build boost and be faster?
>That makes no sense!
>What you will find with a lightened flywheel is that you typically have to
shift faster for a smooth
>shift since the revs drop off faster. So, if you shift faster that means
your back on the power
>sooner so the turbo is spooling down for a shorter period of time and the
boost will come back
>faster.
>What you were told sounds like bunk to me!
>Dan
>
>----- Original Message -----
>From: "Dan Smith" <sad_rocc@yahoo.com>
>To: "The Scirocco List" <scirocco-l@scirocco.org>
>Sent: Monday, August 30, 2004 10:14 AM
>Subject: Re: Lightened Flywheel -2.0l 16v
>
>
>> Does anyone use a lightened flywheel in a turbo car? I was going to but
was told that that would
>be a very bad idea, as it would be hard to stay in the turbo's range on
shifts and 1st and 2nd would
>be pretty much useless. Opinions?
>>
>> Dan
>>
>> Ron Pieper <rapieper@yahoo.com> wrote:
>> Well, logic dictates that it MUST have a downside or VW would have given
us 8lb flywheels from the
>> factory. I'd guess they didn't because:
>> - rougher idle (slightly), esp. when cold; slightly increased tendency
to stall
>> - more finicky takeoff, potential for stalling or chatter
>> - potentially increased rear main bearing wear
>> - low speed operation, potential lurching
>> (this may seem off the wall but I wonder if there's an emissions
consideration in there too -
>> having to do with very quick engine decel on liftoff and the engine
management's ability to
>> control the mixture (meaning emissions) during that state...)
>>
>> In other words, stuff we ain't going to worry about.
>>
>> It doesn't add HP to the engine, but it does add HP to the wheels *in
transition states* - i.e.,
>> accelleration. With a light flywheel, the HP that your engine would have
used spinning up your
>> flywheel is now going to the wheels.
>>
>> All in all, a VERY worthwhile mod. I've had one for years (did it
myself). Wouldn't go back.
>>
>> Ron
>>
>> --- Allyn wrote:
>> > >It seems to be one of those unusual mods that have no downside.
>> > > Larry
>> >
>> > well, there is a downside, but only if you take the lightening to the
>> > extreme. at that point it becomes hard to launch without stalling.
>> > Al
>>
>>
>>
>>
>>
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Cory Langford
'78 G60 MK1 - The Newest Project (and current Daily Driver)
'86 turbo project - The Next daily driver?
'65 Ghia - The next project in the garage
'79 Cheap Ass turbo daily driver - RIP