atb

Brendan,

Mike S. said the crown thickness measured the same.

atb

Kinda makes ya wonder what these lifters with Ti 968 valves, keepers, and rods would do on stock 5 liter with Louie's ITB's and hotter cams (other than burn a huge hole in your wallet). Would that equal a 928 motor that was good for a 7.5K redline?

BC

Awesome. There was an ongoing issue with INA lifters for VWs and others in the same size range as the 944 8V. They were wearing out under high spring pressures/high attack angles on the cams.

atb

Those are my concerns as well. I wonder if some of the weight loss might be attributable to a less durable material? The lifters may be physically the same in outward dimensions, with the VW lifters being designed better so that they don't need as much reinforcement as the OEM units have, but is the weight loss based strictly on the better design or perhaps a difference in the metallurgy?
I hadn't come across anything regarding failures with the INA lifters in high lift applications. It would be interesting to see the specs on the cams that experienced the failures. The fact that they were 2v motors is good for us DOHC builders, in that those cams would have been lot more agressive then those in our 4v motors.

BC

Dennis's motor has some very worked-over cams - which have more lift than GT cams - so lets wish him well and watch closely. I will have the same process done to my cams, and all my lifters are good, but these lighter ones are tempting.

mark kibort

I dont know if you can consider .5mm more lift , "very overworked" as his cams have less improvement than what you would find going from S4 to GT, BUT, I think it should give him a few extra HP. The real work was just the conversion, but that seeemed like a pretty easy mod compared to some of the things ive heard of. It will be interesting to see if the duration change does anything to the shape of the GT motor HP curve.

The motor sure looked good though. It looked like Dennis put in a 928 crate motor!

mk

BC

Very important use-of-words mistake there Mark. I said Worked-over - not over-worked!

123quattro

Those lifters look identical to the VW ones I'm running in my Audi. There was a fair bit of weight savings with them. Mainly in the area where the lifter contacts the top of the valve. My engine spins reliably to 8200 rpm with no issues to date.

mark kibort

sorry, "worked over". But are they really that different? It will be interesting to see the HP curves when its time for the dyno.
mk

mark kibort

I dont think the lifter weight is such a big deal . ON race cars, the main point of falure is the retainers and the style of how they clip to the top of the valve. the valve stem can break, or the valve stem where the retainer can break, dropping the valve in the cylinder. the weight of the lifter being reduced by less than 1 ounce is not really not a hp factor, nor relability factor. hoewever, it could be a factor at the rpm that valve float is an issue, and with the rpms that are limited by our bottom ends, that would never be a factor. the bmw guys might look at this due to their engine rpms approaching 9000s! (and cup cars, etc). those guys done really spend time sourcing lighter weight lifters, but finding valves with better retaining tops and Ti retaining rings to keep thier known high rpm failures down to a min.

mk

BC

It will. I think they have been changed in such a way to make the heads work to their potential in a better way. Also, no other changes were required of the valve pockets.

123quattro

Hi Mark,

I agree that on a 928 these might not be the most useful thing due to engine speed limitations. However, they do work well at high engine speeds. My valve train is all stock except for heavy springs and these lifters. They reduce more weight from the valvetrain than Ti retainers can. Either way, less valvetrain mass is always a good thing.

mark kibort

i dont think the use the ti retainers for weight. (they use them for strength for a given thickness determined by the valve stem cut out) I would be surprised if the weighed .5 of a gram!

the only benifit i could see by using a lighter lifter is a little less force needed at high rpm on the springs. its not attached to the valve and spring, so they are independant of those two components the spring still has to lift the valve and lifter back into position following the cam lobe. since we are talking less than an ounce, its not a HP gainer, even if you multiply 32 of them x 1 oz. thats a 2lbs mass moving .5 of an inch. since we all know F=ma and how this relates to power given the relatively slow speed, this would certainly not be a power factor. you would only do this for two reasons:

1. they were cheaper and were the same quality as what we have.
2. you were worried about valve float with a high rpm engine and wanted to used a slightly less lb valve spring to do the same job and reduce wear and friction on the cam. Its only applying factor is how fast it can return to follow the back side of the cam lobe, and how much force it takes to accelerate it when the cam lobe moves it down. Since the later is near nothing, and the former only deals with optimzing valve spring ratings, i would say # 2 is a non-issue for a 928 engine owner.

mk

Tom. M

Hey..you know something we don't???? I bet we could eliminate those rods from the motor and save even more weight



+1 on the motor config though...if some one doesn't build that combo...and I win the lotto...I'll do it...would be a heck of a motor..

dr bob

Mark--

A lighter lifter means less spring needed to close the valve .and. hold the lifter against the cam. Put another way, with the same springs the valve will close more predictably, with less float, especially at higher RPM's.