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120 HP/Liter is all I ask
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One reason why GT3 engine makes power
Factory CNC machined ports.
 
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"It all started when I began looking around and just could not find my dream car. So I decided to build it myself” - Ferry Porsche |
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11-04-2009, 04:30 PM
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The Porsche GT3 equivalent of Breathe Right Strips. Open her up for a deap breath. Impressive!
Please keep the photos coming. Most of us will never see the inside of a GT3 engine. |
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11-06-2009, 06:12 AM
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Location: S. Florida
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Nice how the valve guides are recessed and shrouded by the port wall.
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11-06-2009, 07:48 AM
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Location: Virginia
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The latest RSR heads are even zoomier, with smaller stems and just beautiful valve seat work. Like jewelry. The X51 street heads are CNC too.
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11-06-2009, 08:34 AM
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another is the crank shown above here(964 on bottom), can you say 8800+rpm?
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Bill Verburg '76 Carrera 3.6RS(nee C3/hotrod), '95 993RS/CS(clone) | Pelican Home |Rennlist Wheels |Rennlist Brakes | |
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11-06-2009, 12:25 PM
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Almost Banned Once
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Location: Adelaide South Australia
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Damn sexy machining...
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- Peter |
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11-08-2009, 04:26 AM
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120 HP/Liter is all I ask
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Quote:
The real "inside" of the GT3 pretty much looks the same as the air-cooled except the Ti rods.
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"It all started when I began looking around and just could not find my dream car. So I decided to build it myself” - Ferry Porsche |
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11-08-2009, 06:31 AM
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Location: The Netherlands, Europe
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Quote:
And: are the Ti rods the same length as the normal steel rods or longer?? Thanks a lot to whoever can answer these, Walter |
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11-11-2009, 10:09 AM
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3 restos WIP = psycho
Join Date: Feb 2005
Location: North of Exit 17
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The Titanium rods are a bit special in dimension. The are 130mm length, just like the early 2 and 2.2L rods, except they have the same rod journal diameter as the 70.4mm crank on the 2.4, 2.7 and 3L cars.
This makes them quite the hot upgrade for an early car - just send your crank in for a rod journal regrind to SC journal spec @ 66mm stroke (or any custom stroke for that matter) and you have something very special!
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- 1965 911 - 1969 911S - 1980 911SC Targa - 1979 930 |
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11-11-2009, 10:13 AM
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120 HP/Liter is all I ask
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Quote:
Ti 130 mm GT3 rods, 89 mm Mahle pistons, 66 mm regound, Early 2.0 case, 40 mm Webers, GE80's 241 HP @ 7300 RPM on dyno so it worked OK, insides below: 
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"It all started when I began looking around and just could not find my dream car. So I decided to build it myself” - Ferry Porsche Last edited by Cupcar; 11-11-2009 at 11:25 AM.. |
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11-11-2009, 11:22 AM
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3 restos WIP = psycho
Join Date: Feb 2005
Location: North of Exit 17
Posts: 7,665
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SWEET! I love the Pankl Ti rods, but had some R&R chromoly rods made to GT3 spec instead. They were about half the price of used Ti rods and a third the price of new ones.
With the Pankl rods coming in at 418g, the moly rods are heavier by 122g (@540g/ea), but still 160g lighter than stockers (@700g/ea). I am curious to see what the big end weights are of a Pankl rod - I have never seen a number to compare the really important numbers of end-weight vs. end-weight.
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- 1965 911 - 1969 911S - 1980 911SC Targa - 1979 930 |
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11-11-2009, 11:44 AM
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Quote:
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11-13-2009, 08:48 AM
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120 HP/Liter is all I ask
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Quote:
Crank was polished on its standard size main bearings, reground to 53mm rod bearings, center main drilled & grooved, counterweights lightened, re-hardened and re-nitride with balance and plug R&R for cleaning (they send out nitride to someone and re-plug job sent to Ollie's machine by Marine). Bearings were Glyco standard mains and Porsche Motorsport GT3 standard rods.
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"It all started when I began looking around and just could not find my dream car. So I decided to build it myself” - Ferry Porsche |
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11-13-2009, 01:11 PM
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Location: Mount Airy, MD
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Is it a secret?
Pardon me for tipping a boat that should not be tipped, but shouldn't that motor do 8.5k on GE80 cams easy? I would assume that you have heads to match... wouldn't 270-280 would be a more fair number??
If I could, why did you choose the GE80 over the RSR sprint (or 906 cam)? I'm trying to make that decision now...
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1967 912 with centerlocks… 10 years and still in pieces! |
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11-16-2009, 09:39 AM
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120 HP/Liter is all I ask
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We were looking for drivability and throttle response more than peak power in a 2.5 liter.
The headers were 1 1/2", only 35 mm exhaust and 37 mm intake ports, single plug, 10.2:1 C.R. and carbs with 36 mm venturis, so a lot of peak power was left on the table and I am sure 270-280 is certainly possible. The good news was we got a broad torque curve of around 190 lb.ft. from 5000 to 6500 and great throttle response. Since we wanted to keep RPM below 7600 in service, an engine with around a 7300 RPM power peak seemed right and the GE80 had done this for us in the past, so we used one again, and got what we wanted, maybe a GE60 would have been fine.
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"It all started when I began looking around and just could not find my dream car. So I decided to build it myself” - Ferry Porsche Last edited by Cupcar; 11-17-2009 at 06:52 AM.. |
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11-16-2009, 01:17 PM
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Location: Mount Airy, MD
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Thanks for background. I've often wondered about the general 'rule' of under camming vs over. I have always wanted to overlay an S with say a 906 cam. Just from eyeballing them side by
side it seems like very little is given away for a lot more on top. Same jist as the early 'rally' spec using 906 cams and pistons with S heads. What would be interesting is if the extra lift 'makes up' for the smaller ports given that the GE80 has 0.51" vs 0.46" lift on the RSR sprint. |
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11-16-2009, 03:40 PM
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Location: So. Ca.
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Why doesn't the RSR or Supercup crank shown in Bill's picture need all the case and crank mods for oiling.
regards |
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11-17-2009, 06:30 AM
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120 HP/Liter is all I ask
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I asked the guys at PMNA about the lack of extra crank oiling and they said Porsche never uses it on their race engines...
On thing of interest on the GT3 engine is the oil pressure relief valve parts package is very different than we are used to. The retention plug has a 36 mm deep recess in it and the spring is different with a different spindle within the spring. The safety valve parts package is the same as usual. I think this set of parts along with a big pump regulates the oil pressure at 90 PSI over a broad range and that may help. This is speculation on my part.
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"It all started when I began looking around and just could not find my dream car. So I decided to build it myself” - Ferry Porsche |
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11-17-2009, 06:51 AM
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I think Geoffrey said it was 85psi, Unfortunately Rennlist is down again so I can't check. It also makes a difference where oil pressure is measured. The 964/993 cases have 2 different taps
JoeMag posted this one w/ the 2 ports labled 
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Bill Verburg '76 Carrera 3.6RS(nee C3/hotrod), '95 993RS/CS(clone) | Pelican Home |Rennlist Wheels |Rennlist Brakes | |
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11-17-2009, 12:42 PM
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120 HP/Liter is all I ask
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My factory book says the GT3 oil pressure relief valve opens at 5.3 bar or 77 PSI, not 90, so I was wrong in memory here, and the safety valve opens at 7 Bar or 102 PSI .
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"It all started when I began looking around and just could not find my dream car. So I decided to build it myself” - Ferry Porsche |
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11-17-2009, 01:01 PM
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1993 Porsche 964 C2 Cabriolet 3.6
1976 Porsche Carrera 3.0
1995 Porsche 993 Carrera Coupe
