Jump to content
SAU Community

Recommended Posts

  • Replies 139
  • Created
  • Last Reply

Top Posters In This Topic

yes it will effect the harmonics of the crank, in much the same way as the flywheel does.It will be greatly offset in magnitude due to the great reduction in inertia hence the vibrational force is far less significant.

There seems to be two schools of thought on the harmonic balancer issure, one is to increase the dampening through the front pulley and thus increase the weight of the pulley. And the other is to lighten it dramatically to reduce the magnitude of force any vibration may have, both systems also rely on reducing the diameter of the front pulley in both cases reducing the 'outer' rotational mass and hence reducing the inertia.

The factory harmonic balancer on the RB26dett was found to produce a harmonic imbalance under extreeme racing conditions when it was in group A racing. They had to change the balancer for a custom made unit to fix engine failure problems.

Having said that, there are many present day R32's in circuit racing who have not changed those same factory balancers resposible for the group A dramas.

The V configuration engines suffer from harmonic issues to a greater extent and even the VG30's can be run safely with light weight front pulleys from what I have heard.

I'd put a light weight front pulley on without batting an eyelid. Having done so to quite a few engines thus far without issue.

the pulleys are the things that the drive belts hang off at the front of the engine - they drive the AC/PS/Alt. The ex cam gears are the gears at the front of each cam that the timing (cam) belt spin to actuate the cams.

  • 3 weeks later...

When I built my RB25 I used an alloy water pump pully to reduce weight and made it a few cm lager in diameter to reduce the possibility of cavitation.

Also used a custom flywheel as well, about 3kg lighter than standard. Although I'm yet engine run the engine as I'm waiting to source my turbo, I can't offer any benefits or downsides.

My thoughts would be to reduce weight of the flywheel, but reducing it too much, say greater than 4-5kg, will reduce the rotational mass too much for the street and torque off boost will be reduced. Can't say how by much but my engine builder said that any more than 5kg is pointless on a street car.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • just an update to this, poor man pays twice  Tried sanding down the pulleys but it didnt do the trick. Chucked another second hand alternator in the na car which I got for free off my mate and its fixed the squelling. Must have been unlucky with the bearings.    As for my turbo car, I managed to pick up a cwc rb alternator conversion bracket + LS alternator for 250 off marketplace, looked to be in really good nick. Installed it , started the car and its not charging the battery.... ( Im not good with auto elec stuff so im not sure if this was all I needed to do but I verified such by using a multimeter on the battery when the engine was running and I was only getting 12.2v )   I had to modify the earth strap for the new LS alternator , factory earth strap was a 10mm bolt which did not fit the bolt on the LS alternator which was double the size so I cut it off , went to repco bought some ring terminals that fit, crimped it onto the old earth strap and bolted it up to the alternator , started the car and same issue. Ran like shit and was reading 12.2 at the battery.  For a "plug and play" advertised kit thats not very plug and play but alas.  My question is , am I missing something ? Ive been reading that some people recommend upgrading the stock 80 amp alternator fuse to a 140 amp but I dont see how that would stop the alternator charging especially at idle not under load.  Regardless ive pulled it out and am going to get it bench tested by an auto elec tomorrow but it would be handy to know if ive missed something silly or have done something wrong.   
    • My wild guess is that you have popped off an intake pipe....check all of the hoses between the turbo and the throttle for splits or loose clamps.
    • Awesome, thanks for sharing!
    • To provide more specific help, more information is needed. What Android screen? What is its wiring diagram? Does the car's wiring have power at any required BAT and ACC wires, and is the loom's earth good?
    • So, now all you need to do is connect the 2 or 3x 12v feeds into the unit to permanent 12v, ACC 12V and IGN 12V that you can find in the spot behind the stereo, and the earth, and then it will switch on with the car.
×
×
  • Create New...