BC

BC

BC

Good profile picture here:

BC

Looks like it is slapped open as quickly as possible, and held there as long as they can, and then slaps it shut.

blau928

Yes,

Same effect as a bigger roller on a roller lifter from Jesel et al on chebbys. Keeps the valve open longer and the curve of the airflow tent is more domed rather than peaky..

Jesel keyed big roller lifters do really interesting things on a big block chebby..

I am sure these have the same effect on the GT3.... Valve timing and lift need to be mapped properly, or the piston may like the valve enough to kiss it and have a divorce...

A rounder lobe is better, and the ramp rates will also be very high due to the increased radius of the lobe tip...

My $0.02

Lizard928

appear to still be German chill cast cams, with extremely high lift, and pretty damn big duration too.

Be interesting to see the ramp #s on it for sure.

Greg,

Would you be so kind as to indulge the rest of us as to why there is such a high failure rate of these for you? are you manually pumping them up and testing leakdown?

mark kibort

great points about the ability to shim a solid lifter in the 928, as well as high speed bleeding of the stock hydralic type lifter at high rpm. (not to mention the quality control , or size matching issues with the VW lifters) I see no reason to go to unproven technology for our 928s, for a lifter with less weight, in an engine that rarely sees over 6500rpm. Call me crazy, but the stock stuff is pretty good for how we race the 928s.

GregBBRD

The hydraulic portion is just the same tried and true stuff that INA has used for years and years...no issue there.

My problem is with contruction/manufacturing. Can't say any more.

Dennis K

Those GT3 cams are nice but part of the engineering that makes them work is the keyed cylindrical (or spherical, I've seen both terms used to describe them) lifters that lurk beneath. These pics are of the 4.0L 6-cylinder engine from the Rolex Daytona Prototype that won the 24 Hours of Daytona in 2009. Note the lifter:













For more pics of that engine, go here: https://rennlist.com/forums/6842812-post54.html

GregBBRD

We are interested in reducing the lifter weight so that we can reduce the valve spring pressure.

Lizard928

Those lifters are interesting.

But what is the service interval for those engines? I wonder how much one of those lifters cost. Would love to get my hands on one....

mark kibort

To reduce wear? Do we have a wear problem with our cams? Im just trying to see the point of diverting from our stock stuff, for the cam profiles that we run, including something like dennis' and the Anderson-Fan cams.

sure, the forces go up so much in a set up like the GT3, running all day long at 9000rpm. But, at 6000rpm, is it really worth the chance to use the stuff that might create more issues because of the quality/consistancy/reliability issues?

mk

andy-gts

lighter wt lifter = lighter assembly with less mass and therefore more hp in the end I am thinking
andy

slate blue

Those lifters in the GT3 race engine may be solids, Porsche used hydraulics mainly with good success but that engine has Ti valves and I believe that engine is the same as the FIA specced GT3 engine used in racing in Europe. When they went to 14 mm they revised the lifter, converted it to solid (9,500 rpm redline) and may have changed the diameter too.

Our 35 mm lifters could handle up to 15 mm (not for street use) the solid versions weigh only 33 grams, so there is no problems there. As to lighter components, there should be gains as longs as everything is matched properly.

Lexus and Jaguar use solid lifters in their V8 engines, very light ones in the case of the Jaguar, I think they were an aluminium composite?

So as far lighter parts go, my general knowledge and an article I read regarding the Ducati MotoGp engine as it uses the Desmo valve system and their engineer happened to say that it was worth a power advantage at lower and mid revs with fuel economy gains too.

That was gains over normal valve return springs and pneumatic systems, the spring pressure required rises quite dramatically as the revs rise. Arrow engineering used to quote about 2% gain in power for DLC lifters and I also saw the friction breakdown for the Cosworth F1 engine and their was still a lot of friction despite DLC coated cams and finger followers.

Going back to those GT3 cams, my guess would be around 270 degrees at 0.050" which is around what F1 engines were running in the early noughties. Given those revs are about the same as now it is probably pretty close today. It has more to do with the profile than the total degrees.

That's my 2 cents.

Greg

Mike Simard

The 2010 Daytona winner uses 35mm hydraulic buckets like ours in its Cayenne engine.

I do know that its cams are the exact same material I use in the cams I make.