Rod Weight

[HPmuirt]

Just fishing for further info as I have asked similar questions before, but it would be good to get definitive weights, answers and opinions in a single thread....

1. What have people weighed OEM rods at?

2. What have people weighed Pauter rods at?

3. At what weight saving, if any, will we see a noticeable improvement in pickup with a mid-performance engine (300-400BHP)?

4. Is there a max/min rod weight for the crank weight to allow perfect balancing? By that I mean, if you have your crank lightened, does it bring the ideal max rod weight below the weight of some rods?

5. At what performance level is it worth putting titanium rods in, or is it worth putting them in anyway if you are prepared to throw big bucks at the engine?

6. I had assumed that Pauters were the rods of choice. Are they worth the extra cost?

7. Is there a recommended piston upgrade for further weight saving, or do most only change pistons when changing pin size or bore size?

These and many more inane questions available at vvvvvv.i-am-an-idiot.co.ck

Cheers n

Si

[Rusty]

This time Si we're on the same wavelength!

[Pembo]

Pembo, was that not the 3B though? ABY rods are ok for 400ftlbs. If i go for a bigger turbo then I need to do some re-balancing for a new clutch anyway so not too worried.

Engine was standard AAN (thought this was stronger but all part numbers seem to be the same!) with a few mods like Piper cams, head ported and polished, alloy flywheel and front pulley. Mapping was done by MRC Tuning on the road and that has given it some large torques!! (When was the North West Rolling Road day?) I thought the engine would be OK running a 34mm restrictor but obviously not.

It will now have Scat rods (balanced both ends! and individual equal), balanced crank, competition mains and big ends, balanced pistons, balanced aluminium flywheel, balanced front aluminium pulley and balanced clutch. This is known as 'zero balancing'.

See you all in Hinkley (Rally of the Midlands) on 20th and 21st June. Still need a navigator!

[Rusty]

Oh, and with a restrictor too, what boost are you running and max RPM?

[S2central.net]

I thought Pembos blew up cos it was a 3B and therefore suffered the fate of Paschen's law - mahoosive spark jump in the dissy causing pre-ignition and catastrophic shock waves.

I have no idea how a K24 turbo can generate enough torque to do destructive damage like that to stock rods... Unless there is a sneaky bottle of N20 disguised as a fire extinguisher in that car.

The 3B and ABY rods are well up for the job in terms of torque, but there might be a benefit in using forged ones if the reduced mass is significant.

From what I remember, every gram of weight saved on ROTATING mass is actually multiplied by a factor relating to distance from the centre of rotation and this results in lower drivetrain losses as a result => more power at the wheels and a more freely revving lil engine into the bargain.

[Rusty]

Hence my original question as I would have shelled out for rods if they were lighter than original and the strength would have been a bonus. Need to talk to an engine builder to get some prices.

[Flat on my back]

So...

du want me ta measure me rods tu'mura or wot...

[Pembo]

Oh, and with a restrictor too, what boost are you running and max RPM?

Was using a 1.5 bar boost gauge and the needle spent a lot of time against the stop. Just bought a 2.5 bar boost gauge.

Never use max RPM because of the restrictor so alway change at about 6000 rpm. Masses of torque and not too bad for power either!

[Rusty]

Ah, 2+ bar on a k24 is pretty amusing!

Carlos, any more data is gratefully recieved. Scats again?

[Flat on my back]

Scat rods.

Standard rods, 144mm, 0.787, 1.992 with ARP 2000 bolts.

Big end weight 408
Small end weight 173

Rod 1-581gms
Rod 2-582gms
Rod 3-582gms
Rod 4-582gms
Rod 5-582gms

Rods wiped clean but need a full dip really.

[Rusty]

Thanks Carlos, that's great.

Jade reported 580g, was that standard rods or other?

What are the weight of the Scat rods then?

[Jamo]

It will now have Scat rods (balanced both ends! and individual equal), balanced crank, competition mains and big ends, balanced pistons, balanced aluminium flywheel, balanced front aluminium pulley and balanced clutch. This is known as 'zero balancing'.

Was everything Zero balanced? As the audi manual states it should be 50% balance?

I know this is how mine was done via Aelred.

[S2central.net]

Jamo - what Audi manual explicitly states that ?

[Flat on my back]

Andy...sorry

those were the the Scat rod weights...but for standard rod replacement...no bigger wrist pins or funny lenghts.

Did that clear things.

[Rusty]

Ah ok, cheers. Just need the weight of a standard rod to compare that to now.