Need help: 993 Carrera 3.8 Factory Powerkit Specs.

[HcK]

Hi!

I've tried to locate the specs and performance figures for factory tuned/converted 3.8-litre 993 Carreras. They came in two versions, pre-VarioRam (model year 1995, engine code M64/05S for manual, M64/06S for Tiptronic) and VarioRam (model year 1996-1998, engine code M64/21S for manual and M64/22S for Tiptronic). All I know is the capacity (3.8 litres) and that the pre-VarioRam version offers 285hp/210kW@6000rpm and the VarioRam version 300hp/221kW@6500rpm.
And this engine is (was) a "Factory Powerkit"-like option on the regular 3.6-litre Carreras, including Carrera S and 4S, excluding Carrera RS.

Now, I'd need some hard facts (preferably backed by a source, either by a URL-link or by the book/magazine it appeared in) about the max. torque of these engines, the revs at which it is produced, the 0-100kph or 0-60mph acceleration and the top speed of a 993 Carrera 2/4 equipped with such an engine and the weight difference (if any) compared to a regular 3.6-litre model.

I know the VarioRam-version of the 3.8-litre Carrera offers exactly the same power at exactly the same revs as the 993 Carrera RS engine, but I haven't found any source claiming they are the same engine, thus offering the same torque. In fact the engine codes for the Carrera RS 3.8-litre (M64/20) and the Varioram Carrera 3.8 " factory conversions" (M64/21S manual, M64/22S automatic) are different, suggesting they're not the same engine. Well, not exactly at least.

The sources I've tried so far are Paul Frere's "Porsche 911 Story", 6th Edition and Peter Morgan's "Original 911", www.supercars.net, www.flat-6.net and a plethora of other car/porsche-related sites found with Google. Nothing so far.

If you have anything on this subject that might help me, please reply!

[pbs911]

I know the VarioRam-version of the 3.8-litre Carrera offers exactly the same power at exactly the same revs as the 993 Carrera RS engine, but I haven't found any source claiming they are the same engine,

I don't have the book in front of me, but I recall Bruce Anderson discussing the simularities between the RS and the 3.8 kit in The Handbook. From what, BA reports that the 3.8 kit transforms the Varioram 993 motor into the RS motor using new heads, cams, pistons, jugs, and DME. I believe he says the kit is only available for the Euro motor or market.

I may be recalling incorrectly, but I do know there is some info on the 3.8 kit in there.

[Bill Verburg]

This is from the factory "Technical Specifications" book

'95-96 911 Carrera RS
Engine type M64/20 the RS recieved vram in '95 a year ahead of the normal models

Max engine power to EC 80/1269 kw/Hp 221/300 @6500

max. Torque to EC 80/1269 NM/kpm 355/36.2 @5400

Engine weight (w/o ZMS) kg/lbs 230(221)/507(487.2) this is ~2kg lighter than a nonvram normal 993 engine

Bruce Anderson has some errors in his book relevent to this issue but appears to indicate the same hp but has reported US style torque as 261 ft/lb @5400

Aichele reports the same #s

Frere reports 300PS@6500 w/ 360 n/m(265.5 lb/ft)@5250

The bigest difference in the heads vs nonvram is larger 51.5mm intakes, a slightly wilder cam, slightly larger runners.

[Britwrench]

The Porsche Motorsport 3.8 "kit" used in Europe uses mechanical valve adjusters. There was an article in one UK magazine about Porsche Cars Great Britain demonstrator Carrera with the kit installed. I drove it and the power increase was certainly noticeable. Idling, the cam design caused some loping and the valves needed adjustment more frequently than a 964 (no idea why). Overall a good idea.

[Bill Verburg]

There are/were aftermarket kits which use mechanical followers, as do the RSR engines, but all of the factory RS quoted above were hyd.
Here are some pics of the factory kit







and one more from Gert Carnewal's site

[Britwrench]

Bill, I adjusted the valve clearances on the PCGB installed kit, they were mechanical adjusters

[HcK]

Thanks for the help guys. I also got some other reports and found some atricles that seem to indicate that the 3.8 Carrera engine kit offered the same power and torque as the Carrera RS engine, and at the same revs. So that's the figure I'll go by.

And for anyone who's interested, the Porsche importer in Finland (http://www.autocarrera.com) reported on the pre-VarioRam 3.8-litre kit as follows:

Powerkit (option code X51)
Engine code: M64/05S manual, /06S Tiptronic
Capacity: 3746cm3
Power: 285hp/210kw @ 6000rpm
Torque: 350nm/257ft-lb @ 5000rpm
Revlimit: 6700rpm
Compression ratio: 11,3:1

[Bill Verburg]

Britwrench, As I posted the regulat production RS option was hyd. lifter, though many were changed to mechanical thru special wish or after market(which includes the various distributors and dealers).

There were 2 reasons for the change. The first was to use happier cams, the second was somewhat more obscure. Many of the original owners had their cars dynoed and were disappointed w/ the results. Upon further investigation it was found that the 993 style of securing the sprockets to the cams allowed a slight shift in cam timing which was detrimental to max power. The cure was to change the sprockets to the 964 style. Many figured that they might as well go to the mechanical followers as well.

Mine has the oem hyd. followers w/ the updated(actually backdated) 964 sprockets.

[Britwrench]

Yes, that's true Bill, we sold a few 3.8RSL (street version) and at least one of them had the lack-of-power "discussion" with Porsche AG about that. There was a technical bulletin regarding the cam timing, including one about the acual tool needing modifying. You may be right about
the mechanical adjusters, although the kit also included a "Porsche Motorsport" sticker for the engine.

[Bill Verburg]

Here's a nice pic of the mechanical rocker upgrade,

[Britwrench]

That's the shim type adjustment, the street one was with the screw and nut as used in the 964.

[Bill Verburg]

good eye!