N51

By my calculations, the difference is 5.6%(.2/3.6). I'm in agreement with Steve Weiner. The 3.8 is an excellent platform for modification. In contrast, the 9M heads, at $11000USD and 10 hp, are very expensive. The same, or greater hp can be derived from porting your existing heads - and at a greatly reduced cost.
None of this should be considered by a short term owner. It takes a long-term commitment to the car you now enjoy. Best to all that join in the fun.

Noah

Red rooster

Noah,
If the "3.8" was 3800cc you would be right. With 102 mm bore size you get 3746 cc . Thats + 4% .
Maybe it makes sense if your motor needs pistons and barrels. I still think that for the cost its not a good $/bhp solution.
Be interesting if anyone has ever put 3.8RS cams in a 3.6 Vario .300bhp maybe ?

Geoff

N51

In the Porsche community, I'm sure someone has done it - and it would be interesting. These engines have been around for many years, with many varying alterations. I'm a little surprised you haven't come upon the same as you proposed, in your experience. :-)

Best,
Noah

Steve Weiner-Rennsport Systems

Geoff:

We've done a LOT of these 3.6 "RS" spec motors that have 100mm P/C's, RS cams, RS intake valves, proper software, and a good exhaust.

These make very close to the same HP as the 3.8's with a little less torque down low. With good close-ratio gears, these things work quite well and IMHO represent a very good value.

Typically, we see anywhere form 300-310 HP on our engine dyno with such configurations and even more with headers and a good race muffler.

Jean

It is not about the incremental maximum HP it gives, it is rather about the torque across the rev range which, while not huge, makes a very nice difference to the throttle reponse, and almost 3seconds from 0-200kph.Those are very substantial gains!!

I believe they were built and used on the performance versions for a reason..

NineMeister

Here is the run of the green to date:
The basic top end parts package of cylinder heads, valves, springs, retainers, platforms and sports camhafts retails for £5995 and you have a choice of hydraulic or mechanical camshafts within the deal. For extended high rpm track use I recommend fitting mechanical followers, you can simply use the 964 follower assembly for this but you will have to run a restricted oil gallery in the shaft - we are currently looking into making these shafts and supplying this as a mini kit for around £600 including the 964 rockers and adjusters. To achieve the results we have you have to improve the air velocity of the intake flow to the head and also reduce the backpressure in the exhaust. The exhaust is easy, we simply fit 100 cell split flow cats (£1250) and leave the silencer alone, the intake is a little more involved.

On the non-varioram model the stock intake is fine, although there are small gains to be had from port matching the injector stack to the head and the plastic manifold. A larger throttle body also helps response but is not critical to the top end power. With a suitable free flow air filter we expect to see 340-350hp & 435Nm from a non-Varioram following a live remap on UK 98 Octane fuel.

The Varioram is more involved. Following experiments on the last 2 engines we built, we found that the runner sections of the varioram manifold were badly made and feature a neck or restriction in the casting approximately half-way up the cast runner. Just to be clear about this, what I am talking about are the two bolt-on cast sections of the Varioram manifold that have 3 individual pipes feeding the cylinders, ok? All we do is remove them and carefully clean up the inside of the port to remove the restriction (narrow diameter) and provide a smooth surface and gradually tapering path for the airflow. The second modification is to taper machine the injector stubs to match the aluminium runners. Do all this and in combination with the head/cam package and you will find up to 15hp more power. Again, with a suitable air filter and live remap on 98 octane we see 350-355hp & 430Nm. To clarify the torque figure, the peak torque is usually a fraction lower on the varioram but the spread of torque is always much better.

Fitting the kit is obviously a top end rebuild, so on the 993 once the engine is out, the work done and the engine back in with a wheel alignment, you will be looking at 30-40 hours worth of work. If you include the manifold rework, injector stack modification, gaskets, oil, cats, engine labour and live remap our price for doing the whole job from start to finish comes in at under £11,000+VAT.

We have also done one 3.8 version of the engine with the 9m 102mm Sport pistons & cylinders, which are an ideal upgrade for higher mileage engines with tired cylinders. The 9m pistons are design matched to the cylinder head and run 12.0:1 compression with improved squish control and hence combustion efficiency, the first car to have these fitted with the heads made 360hp and 450Nm, the major advantage being significantly more torque everywhere in the range. The 9m B&P set is £3495+VAT, and after allowing more labour to do the bottom end, the full 3.8 version of the engine conversion costs around £15k+VAT, which is not bad for an engine that makes the same power with more torque than a mk1 GT3. Both package prices exclude the mechanical rocker upgrade.

Interestingly we are just about to ship a kit to Hong Kong and currently have a package on test on a Superflow engine dyno in Japan. Results from Japan are looking promising their 3.8 litre 993 VR engine with the 9m head package on standard cats is already making more power than their factory 993 Cup engine, inspite of not having the recommended intake manifold modifications.

The problem for us is that we cannot remote re-program ecu's, especially the tricky US OBD2 unit fitted to the export version of the Varioram, although we will be investigating other options to get around this sometime soon. I should also mention that we can do a SAI port version of the head if required (currently special order only, will be a stock item later in the year), and obviously we are obviously willing to ship parts packages on a "not for highway use" basis if you have a shop who would like to get involved with building one of our engines.

NineMeister

Not sure where your number came from Noah? The minimum gains we have found on a 993 engine with our head/cam package are in the 60+hp range and a Japanese tuner testing the same package on his Superflow engine dyno is up by 45hp without the benefit of our recommended intake and exhaust modifications. Last week we also tested a 3.6 964 engine with the 9m head/cam combination and Motec, it consistently posted 350hp.

Lawrence_P

I have heard a lot about these guys. http://www.motormeister.com/

Red rooster

Steve,
Thanks for that. Confirms what I was thinking .On with the master plan !!


Noah,
I have around long enough to know that asking for other views is a good idea !
911s are surrounded by mystique and fashion , bit like womens shoes ! and can cost as much !!!

All the best

Geoff

Bill Verburg

The 3.8RS is a very satisfying engine, as Jean said, because of the across the board torque, cams alone can get you almost the same hp but it's all at the top.

The 3.8 cost is a significant deterent, but if you shop smart it can be done far more reasonably than most of the #s I see thrown around, for instance there is a set of 102mm RSR p/c now(I have no ide of their condition)

gearing is far more satisfying for far less money and potential complications from emission compliance

N51

The numbers are from you - from our private emails, previous threads, and now again here.

You have previously stated that you tuned an otherwise stock 964(with cat bypass) to ~340hp, using Motec. Now you state you've tuned a 964, with your heads/cams+Motec to 350hp. That's a 10hp gain for $11000.


Noah

Jack of Hearts

NineMeister

Have you been taking lessons from Loren?

Can I just point out that this is a discussion about the 993 engine on the 993 forum, so all my comments on this thread have been quoted on this basis only.

As I have stated on many occasions, the 964 have different heads which perform much better than the 993 but it has an inferior engine management therefore for the 964 we recommend engine management changes as the top priority. In the case of the 993 the engine management is more responsive to engine changes and the heads are the bottleneck to performance, hence why I I have made the recommendations above. And before anyone asks why you cannot simply fit 964 heads to the 993, you can, but aside from the issue of finding suitable donor units you also have a problem with the RHS exhaust flanges which require different bolt centres, so they are no a direct replacement.

N51

Then why do you introduce Loren into the discussion?

This is a discussion in regard to the merits of a 3.8 engine. You chose to use it as an opportunity to advertise your heads. You chose to introduce the work you had performed on a 964. You asked where my numbers came from. They are from you. You own them.

For the record, I consider Loren a valued member of Rennlist - one whose knowledge and honesty is appreciated. I'm always searching for knowledge. But it is not I who need lessons in honesty.

Noah

jdistefa

Why why why... Yes, I know, popcorn. But seriously, can you guys take this kind of interpersonal dysfunction into the PM domain?