Apex996

991 GT3 Hydro Lifters - 9000 RPM !?

OK geeks, engineers and motorheads... Is there any detailed info floating around out there regarding the new hydraulic lifters that can deal with 9000 RPM? Any info yet on the rocker arm ratio and/or cam dynamics?

Any detailed engine "cut-ways" showing the valve train details? I can't make out the lifter or rocker design from this one. There's probably a larger version of this out there.



I found Herr Preuninger's video interesting when he presented the rocker arm design as unique or somehow beyond what other engines were doing. Surely Porsche is familiar with the American V8 engine So perhaps there is something else unique about their design?

aussie jimmy

peter brock used roller rockers in holden commodores back in the late 80's.
nothing new.

911rox

lmao... I was thinking same when they first announced Jimmy, haha... Shame they didn't throw in a Polariser and call it a "Porscheriser"

stevecolletti

I'm pretty sure that the Ferrari F355 had both 8500+RPM hydraulic lifters and rocker arms.

And I'm no expert on motorcycles, but I though they were using rocker arms on most of the 'special' overhead cam bikes to get the proper valve geometry - and packaging. I'd assumed that this was what Porsche was trying to do with this 9A1 derivative.

911SLOW

I will have some tech info soon.

Apex996

sigh ...

edit...

LOL, Slow, You must have hit enter right before I did
Slow to the rescue again! Thank you for always adding value

StirlingMoss

Here is a close up.

CTT-QTR

I just hope there won't be any maintenance for this i.e valve adjustments.

GrantG

No, the hydraulic valve adjusters in the post above mean there will not be.

The F458 revs to 9k and I don't think it needs valve adjustments either...

allans

Seems the only reason the rockers are there is to control valve gap? ?? Allan

sand8

Yes, important when going up to 9k rpm. It can be without the rocker and the hydro can be in between cam and valve directly, just like in convensional DOHC setup. But, this will make the head higher.

aussie jimmy

i reminisce though, and found this video. for those that don't know, peter brock was killed around 10 years ago in an accident when competing in a tarmac rally.

HiWind

Lol amazing vid - thanks Jimmy!

ToSi

neat.

Anyone know valve lift or cam duration for this (or prior GT3)? Is the techbook out yet? thx.

BGB Motorsports

The 9000RPM durability is more likely a result of the titanium engine parts in the form of connecting rods and pistons that are left solely for duty north of 8000RPM. The single biggeest difference internally as far as hardware for the new motor is the use of those parts, as Porsche won't rev over 8K without GT3 internals.

I thought that the revisions to the lifter design were because in years past they had variable valve timing on intake and exhaust. The new 991 motors have variable lift and duration on the intake side and I'm assuming they went a step further on the GT3 to enhance the variable valve clearance OR they're trying to mimic what's available on the street car to create more power opportunity? Specualtion...i'm not an expert NOR am a Porsche employee. I'm just the guy in the trenches.