Christer

Tony

The non-varioram had 272hp, whilst varioram cars had 285hp.

johnfm

TOny
the varioram cars with pinstripes had 305 hp.

Bill Gregory

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva"><strong>I suggest that there is only 12 bhp difference between the964 and 993(non-varioram)</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">1994 M64 05/06 993 = 272 hp
1993 M64 01/02 964 = 250 hp

tonytaylor

I was being deliberatly contentious ,
I know that the 964C2/C4 are rated at 250hp and the non-varioram 993 is 272hp - a difference of 22hp. However the 964RS had 260hp and the engine, exhaust,airbox is the same ( the plastic air intake plenum is different to the alloy one of the C2/C4 but these were adopted by the later C2/C4, still rated at 250hp, and anyway I`m lead to believe is only worth a couple of hp in any case)- it shares the same part numbers. The only change was the ECU - hence I`d say the 964 was rated at 260hp -giving a difference of 12hp with the 993
Bill,IMHO I`d say 6hp from the headers is about right

Kevin

The bottom line is how my $ss feels the change. Being that my RS was lightened this conversion lights up the 3.6.. It is night and day. To me if I can afford to spend 4 to 5 grand on a handmade header setup and then trash all the gains with Cats just was not fiscally feasable. You also have to take into account that our crappy gas on the west coast plays issues in performance. With the 993 exhaust with cats, the factory system for little dollars invested wakes up the car...

Bill Gregory

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva"><strong>...the 964RS had 260hp and the engine, exhaust,airbox is the same... </strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Well, very close at least. The RS had selected matching of more balanced pistons and cylinders. Spec calls for RS pistons weighing 644-648 grams each versus the two piston groupings for the non-RS 964's of 644-652 grams and 652-660 grams. There was the lighter flywheel, only one drive belt for the fan and alternator, no power steering pump on left hand drive versions, and, as you mentioned, the plastic air intake. Oh, and some timing magic in the DME and a 98 RON gasoline requirement.

Bill Verburg

As Bill G. has pointed out the 964RS pistons were carefully selected, not only for weight but also for c/r. The run of the mill 964 usually has less than advertized c/r unlike the RS which have nominal c/r at least.

I have dynoed my 964 powered Carrera w/ headers and found little gain over stock.

I have also seen 964s w/ ~270 rhp just from being sure compression was up to snuff, using 993SS cams, a custom chip(ala RS) and undersized SSI pipes.

The 993 headers(w/ properly rotated passenger side flange) offers tremendous bang for the buck, though you now face the problem of putting mufflers on it if the cat is also used. Further, happier cams(993SS or similar grinds) will really make that engine come alive.

Bill Gregory

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva"><strong>The 993 headers(w/ properly rotated passenger side flange) offers tremendous bang for the buck, though you now face the problem of putting mufflers on it if the cat is also used. </strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">One muffler option might be the Fabspeed Supercup exhaust - Joe says, as long as you have the 993 cats on, it's Lime Rock legal (which is around mid-80 db's), which means women won't pull their children away from the road as you pass. Here's a picture:

<img src="http://members.rennlist.com/sansho/supercup2.jpg" alt=" - " />

No affiliation, just investigating options.

Bill Verburg

I keep forgetting that you 964 guys have room in your 1/4 panels for mufflers

tonytaylor

Bill Gregory and Bill Verburg,

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva"> There was the lighter flywheel, only one drive belt for the fan and alternator, no power steering pump on left hand drive versions, </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">None of these ought to affect hp at the crank although they will affect rwhp.

The blueprinting of the engine is a diffrent matter but I wonder how far out a stock 964 is cf the RS since we are talking about what was a quite expensive car new. Having said that, most RS fans suggest that 260hp is a minimuim. (but they would wouldn`t they!)

It`s not that I don`t agree that the headers on the 964 are sub-optimal or that 993 headers are better but that I`m not convinced that 993 headers will give anywhere near 22hp

Bill Gregory

Tony,

As I recall from various discussions, measured compression ratio's shows the stock 964 around .5 or .6 below the 11.3 spec. Advancing the timing and bringing the compression ratio up to spec might be a reason to spec 98 RON.

Joe@Fabspeed

There are no gains in torque and horsepower worth the aggravation necessary or the weight penaly of BOLTING on and fabricating 993 exhaust onto a 964. Dynoed over 14 of these conversion systems.

If you have a 964 and want more cost effective power with HEAT a catbypass pipe and primary bypass pipe or a REAL performnace single or dual outlet muffler will make more power than all that stuff with no "aggravation factor". When emissions are a criteria you just "slap on" the catalytic converter and get your stickers and then remove later. The 993 catalytic converter is a BOAT ANCHOR and is the completely wrong place interms of reducing inertia and polar monet for better handling. Getting weight off any 911s or anyones *** is paramount.

If Ultra light weight is important and emissions and heat are not criteria.....and you want maximum power and torque to launch off the corners and instantaneous throttle response get 1.75" headers with merge collectors and a dual inlet dual outlet muffler. With that in mind you had better tune for the reduced backpressure with a revised CHIP or you might as well stay with the catbypass pipe or a performance muffler and/or a primary bypass pipe.

Bill Verburg

While headers may not increase peak power much on a stock 964, I do agree w/ Joe that throttle response is much improved and the weight savings is considerable, ~30#s all in the extreme rear of the car. I also agree that a chip should be part of the program and that w/ stock cams a cat bypass is probably the best solution especilly when $ and aggrivation is factored in.

Kevin

Here is my muffler fix. When I first did the conversion I was immediately shocked at how quite the system was. So, I decided to cut the mufflers open. This is what I found out. What I ended up doing was to remove all the guts. I later welded two J tubes out of 304 stainless from Burns Stainless. I found out for my taste that I only needed 2.5" of perferated pipe for sound deadening. Another benifit is the lightening of the complete system.

<img src="http://boards.rennlist.com/upload/muffler.JPG" alt=" - " />

johnfm

Don't the more tightly specced internals of the 964 also allow it to redline a bit higher - or did I dream it!!

These peak HP figures are all a bit of a red herring anyway - I think its delivery of torque & power in the rev range that is more crucial than the headline figure. I recall that the GT3 gives the GT2 about 100 HP, yet is only a few seconds slower on the Nordeschliefe.

Also, ain't it weird that I was suggest higher C/R, chip tunign and 98 RON fuel earlier in this post and....that's what the RS seems to rely on for added grunt!