sfl993t4

What is the difference between the GT2 Evo Cam and the RS Cam in terms of power band etc.?
Thanks for your help
Steve

Jussi

I'm also interested in these cam questions.
I've been offered EBS Racing cams for my 3.8TT project. What do you think about these cams?

Kevin

A little Porsche camshaft history.. I know that some of this info might be old new, but some of it is newer stuff.

930 Int dur 216 deg .387 lift Exh dur 207 .345 lift

964 Int dur 238 deg .464 lift Exh dur 230 .425lift
Very Popular

911SC Int dur 229 deg .455 lift Exh 220 .402lift

993TT Int dur 234 deg .454 lift Exh 218 .430 lift

GT2 EVO Int dur 248 deg .485lift Exh 232 .470 lift

RS Int dur 242 .490lift Exh 228 .455 lift

Duration was printed a .050

Most centerlines were ranged from 111-113 degrees

You really can't go wrong with 964 cams or hybrid 964 variations, however the EVO and RS camshafts work very nice. For myself I lean towards the larger lift on the exhaust valve, with a tad bit more duration of the EVO cams..

Disclaimer, these numbers were transcribed late, and I might have entered a wrong value somewhere, I will proof tomorrow..

Red rooster

Kevin,
The numbers I have for the 993tt are
inlet ,12BTDC-63ATDC = 255 degrees
and exhaust , 45BBDC - 5ATDC =241 degrees . All at 1.0 mm lift.
I was always suprised that the inlet number looked pretty big.
Can you or anyone else give me the correct numbers ?

Geoff

Geoffrey

Red,

Actually, it would be 63ABDC, not ATDC for the intake valve closing event. With the numbers you gave above, the intake has a lobe centerline of 115.5 and an exhaust lobe centerline of 110 degrees for a lobe seperation angle of 112.75. I think Kevin misspoke when he said the centerlines were in the 111-113 range. Many of the Porsche camshafts have a LOBE SEPERATION angle in that range, however, most aftermarket camshafts move these to a more agressive position with a good compromise in the 107/108 lobe separation angle range.

Rob 97 993c2

Based on Kevin's #'s , why do the 993tt cam #'s seem to be a step backwards?
That said, im very ignorant on this topic, so forgive me if Im misreading.

Kevin

Red Rooster at 1mm the measurement would be roughly at .040 Most US manufactures and gear heads use the .050 measurement for durations. Basically you have to find a common across the boards unit to compare cams, so typically we use .050

As Geoffrey mentioned I was off with the lobe center for the 993TT it is actually 115 degrees.. SC cams were 112 Intake and 113 exhaust. GT2 EVO and RS were 112, 964's are 113.. The racing RSR camshafts have a lobe center of 109...

Geoffrey

Step backwards in what respect? You have to remember that performance is not the number 1 priority of any OEM's engine program. They have emissions and fuel economy parameters that take priority over performance. As such, intake/exhaust valve overlap, particularly with a low compression turbocharged engine is not a good thing for either of those criterias. Further, there is a tradeoff between high rpm running and low rpm running and camshaft profiles with respect to engine torque. The GT2 EVO engine was a racing engine, and in fact has different camshafts than the 911 GT which was the road version of the the GT2 EVO. It was not bound by the same design parameters as a street car and therefore can be more agressive. In my opinion, the GT2 EVO cams are great street performance cams, but not nearly large enough for a racing environment, especially with heads the flow very well.

There were several versions of the racing RSR engine depending on sprint or endurance configuration. Some of the camshafts were made by Theilert and the lobe separation angles ranged from 106-109 depending on which camshaft was installed in the engine. And of course, some of the teams used custom grind camshafts. FWIW, the GE series of camshafts are ground on a 100 degree lobe separation angle.

Camshafts are very often measured at some "lift point" because it is very difficult to accurate determine the point where the camshaft lobe begins to lift the valve. .020" and .050" are two very common ways to advertise camshaft duration. In fact, every camshaft I have ever measured will show the lift decreasing by .001" from the base circle immediately before the lift begins. This includes Porsche, BMW, Schrick, GE, and the custom grind cams I've had made.

sfl993t4

Has anyone measured any of the Ruf cams to see how they compare?

Steve

Rickard 993 Turbo

Now i have a plan made out

I was at Micke Svens today, one of the world best porsche builder and tuners

I was confident that kkk24 car with camshaft,free flowing exhoust,custom tuning of ecu,big oil cooler and some more small stuff would give me 500-520hp at 1,1bar..We have sheel V power here so that's a plus also

Red rooster

Sorry about the ABDC typo.
I am still not clear about the standard 993tt cam figures ,as Kevins quoted 964 durations are factory numbers measured at 1.0 mm lift ( the standard factory method ! ).

It would appear that on the information I have, the 993tt has pretty vigorous cams , bigger durations than the 964 ?

Can someone post the factory angles for the 993tt for Inlet opens/closes ,Exhaust opens/closes all measured at the factory 1.0mm lift ?

With this information decisions can be made about what cams to use in different motor specifications.

Sorry to be a PIA but I think this is important !

Geoff

Kevin

Geoff in the US most camshafts are done at .050 for a standardized comparison. I used .050 on all the listed cams.. .040 Duration for 964 is 246 and 232

Jussi

Are these tuning cams, like GT2 Evo and RS Cams, always for mechanical system, not for original hydraulic ones?

Kevin

There are some performance grinds that one can use the hydraulic rockers.

Red rooster

Kevin,
Checked the 964 1.0mm lift , duration numbers in the factory manual.
Inlet opens 4 BTDC ,closes 56 ABDC = 240 degrees

Exhaust opens 44BBDC , closes 4 ATDC = 228 degrees.

I am going to have a call around to see if I can find the factory 993tt numbers.
The 993tt numbers I have, at factory 1.0 mm lift ,gives durations longer than a 964 / 95 993.

I just want to know for sure ,because putting milder cams in aint the way to go !!

Again if anyone has a Volume 1 , engine , shop manual for a 993tt , can you look in the front and find the cam timing numers .

All the best

Geoff