m20 harmonic balancer

[doktor_b]

i haven't seen anyone run one. is this just because one isn't available commercially (doesn't seem like a good enough reason)? or is there a compelling reason? (like m20's don't generate harmonic vibrations. lol)

i have a theory on how to make one work, but i want to see if anyone else out there has any info on why not or if there is something already available that i can use on my application.

[nando]

A lot of money for basically no gain is probably why.

[doktor_b]

A lot of money for basically no gain is probably why.

yeah, i understand there won't be any hp gains. But what i'm looking for is increased life of the engine. long stroke, high rpm, plus lots of miles/use seem like a great candidate for a harmonic balancer.

it just seems odd to me that there is so much that's been done with the m20 and no one has done this.

[jlevie]

If I recall correctly, the OE harmonic balancer for an S54 has a reputation for failure. Which could be why an aftermarket part exists. Dunno about an S50.

An M20 engine has a harmonic balancer. It is the two piece rubber bonded part on the front of the crank shaft. If you want to get longer life from the engine, balancing all of the rotating/moving parts, getting uniform piston deck heights, and exact bearing clearances is the way to go.

[doktor_b]

If I recall correctly, the OE harmonic balancer for an S54 has a reputation for failure. Which could be why an aftermarket part exists. Dunno about an S50.

An M20 engine has a harmonic balancer. It is the two piece rubber bonded part on the front of the crank shaft. If you want to get longer life from the engine, balancing all of the rotating/moving parts, getting uniform piston deck heights, and exact bearing clearances is the way to go.

all the parts for the new rotating assembly are balanced to within +/- .2g

i know the stock crank pulley has a bonded rubber balancer built in, but i would rather have an ATI or a Fluidampr if i can find a way to make one work. i had considered an ATI for an s52 and rotating the reluctor wheel 240 degrees clock wise to align it for the m20 and fitting a different pulley (v-belt for stock, or perhaps cogged for full-retard). i also wondered if i could just bolt up one for an s52 and adjust my settings in MS2 for the differently aligned trigger wheel. (pulley situation otherwise resolved)

however, i won't pay $1000 for an ATI from VAC and still have to cobble it together. i will collect a used fluidampr or ati damper from a different engine and make the pulleys and reluctor ring.

i guess we'll see what i can make work and how that turns out.

[digger]

IMO the reason M20 hasnt needed aftermarket vibration damper because almost none of the really big stroke motors rev past 7k, 8k for long periods of time and in most cases the firing pulses are weaker than on the 24V motors at those rpm.

if you were using a S52 crank M20 and making power at 8k then it might be worthwhile long term otherwise get a new stock one with full life remaining (unstress and unon heat cycled with longer fatigue life remaining) they are still pretty exxy though about $400

ring up Jim Rowe from MM if you have a spare hr im sure he will have thoughts on the matter. they used to sell lightened vibration dampers

[doktor_b]

IMO the reason M20 hasnt needed aftermarket vibration damper because almost none of the really big stroke motors rev past 7k, 8k for long periods of time and in most cases the firing pulses are weaker than on the 24V motors at those rpm.

if you were using a S52 crank M20 and making power at 8k then it might be worthwhile long term otherwise get a new stock one with full life remaining (unstress and unon heat cycled with longer fatigue life remaining) they are still pretty exxy though about $400

ring up Jim Rowe from MM if you have a spare hr im sure he will have thoughts on the matter. they used to sell lightened vibration dampers

i will be running an s52 crank in my m20, and i hope to still be making power up to 8k.
i'll look into a new, stock damper.
and i'll see about talking to JR at MM for sure. it'll be good to get another perspective on the topic.

[jlevie]

I think there is little doubt that the engine can make power up to 8k. The question would be how long it would last. I know of pro built S52's that had short life (broken cranks and/or rods) when run up there, probably from harmonic vibration. Limiting the engine to 7k sounds a lot better.

[digger]

i will be running an s52 crank in my m20, and i hope to still be making power up to 8k.
i'll look into a new, stock damper.
and i'll see about talking to JR at MM for sure. it'll be good to get another perspective on the topic.

is this a NA or FI engine?
lightened drivetrain and reciprocating parts will help.

[jalopi]

I think there is little doubt that the engine can make power up to 8k. The question would be how long it would last. I know of pro built S52's that had short life (broken cranks and/or rods) when run up there, probably from harmonic vibration. Limiting the engine to 7k sounds a lot better.

Tis good advice

[doktor_b]

I think there is little doubt that the engine can make power up to 8k. The question would be how long it would last. I know of pro built S52's that had short life (broken cranks and/or rods) when run up there, probably from harmonic vibration. Limiting the engine to 7k sounds a lot better.

yeah, i'm not going to go too crazy with the revs. i just want the power to be there if i need it.

is this a NA or FI engine?
lightened drivetrain and reciprocating parts will help.

NA.
lightweight flywheel, IE h-beam rods, Ross pistons (also from IE), S52 crank. assuming the stock m20 and s52 cranks weigh the same, i'll save ~3-4lbs with the new rods/pistons. the flywheel should be another 10-12lbs saved also when it's done. (lightened stock. i'm still going to drive it on the street, so there's no need for an aluminum one)

Tis good advice

thanks. ;)

[digger]

yeah, i'm not going to go too crazy with the revs. i just want the power to be there if i need it.


NA.
lightweight flywheel, IE h-beam rods, Ross pistons (also from IE), S52 crank. assuming the stock m20 and s52 cranks weigh the same, i'll save ~3-4lbs with the new rods/pistons. the flywheel should be another 10-12lbs saved also when it's done. (lightened stock. i'm still going to drive it on the street, so there's no need for an aluminum one)


thanks. ;)

you'll need a top notch cylinder head, aggressive cam and a new intake manifold to be making power at that rpm with that much cubic inch in the bottom end.

i'm doing a similar build for the street, i'm contemplating a JBR flywheel might stick with stock lightened flywheel and 240mm clutch though

[doktor_b]

you'll need a top notch cylinder head, aggressive cam and a new intake manifold to be making power at that rpm with that much cubic inch in the bottom end.

i'm doing a similar build for the street, i'm contemplating a JBR flywheel might stick with stock lightened flywheel and 240mm clutch though

the head isn't going to be too fabulous. just a little cleaning up, bigger valves, and a 288 cam.

the intake manifold will remain stock until i upgrade to ITBs....but it's going to be a while.

[digger]

the head isn't going to be too fabulous. just a little cleaning up, bigger valves, and a 288 cam.

the intake manifold will remain stock until i upgrade to ITBs....but it's going to be a while.

i doubt you will need to rev it to 8k , a limiter at 7000 maybe 7200 will be enough

[doktor_b]

i doubt you will need to rev it to 8k , a limiter at 7000 maybe 7200 will be enough

that's exactly what i was thinking. i set the limiter on my last engine at 7200 (fully forged, built, turbo 3.2L vr6 in a VW)