Strange Engine Characteristics !!

Richard Knight · Jul 12, 2004

Hi Folks
I have the 3.6L, 996 engine in a my2001 Boxster S. I've now covered about 20,000 kms on the new engine and have noticed an irritating trait.
At 3,000 rpm on an even or slightly trailing throttle there is a noticable, momentary hesitance in the engine. I guess it's at the point where the vario-valve timming is doing it's magic.

In order to run the 3.6L lump the Boxster also runs with an ECU from the 996 so the programming should make for a smooth transition of the cam advances etc.

Is my engine the only one that does this or have any of you noticed the same thing??

Cheers Richard.

Guest · Jul 12, 2004

I have seen this mentioned many times on rennlist. I haven't witnessed it myself on my 3.4 996 but apparently it is a known feature (like it or not).

See this thread: http://forums.rennlist.com/rennforums/showthread.php?s=&threadid=97770&highlight=surge

TISPKJ · Jul 12, 2004

Richard I have just had similar problems on my 3.4 996 sorted and it was down to faulty variocam units both have been replaced, interestingly at no stage did the engine management light come on would suggest you get these checked if the above answer is no good to you.

More interesting though, tell me about your car, I have read about the 3.4 conversion and that seemed great so yours must be superb, did you buy it or do the work yourself ? I had an S before the 996 and dreamt of sticking a GT3 lump in it .........

Sorry if you have told the story before ....

Regards Paul

Richard Knight · Jul 14, 2004

Thanks for the replies.
It's strange that both of you have had this with the 3.4L lump. I ran the 3.4L lump in the Boxster for 6 months and had a very enjoyable 12,ooo kms with it.
I didn't notice any hesitance with it, but it had to go back to Germany to fix a strainge "chirping" sound . This happened at around 800-1000rpm only. The entire engine was stripped and nothing of any consequence was found, other than a slightly loose spark plug. This was subsequently put back in and torqued up correctly. It ran like a dream after that.

Paul . To answer your question, I had the 3.6L lump installed from scratch in my car. It took 18 months of heart ache and 5 or 6, 2,500 kms round trips between Barcelona and Cologne to get it right!
The main to problems were , 1) Getting enough air into the engine and 2) matching the 3.6L engine to the Boxsters electronics.
The problem of air flow was over come by fabricating a custom carbon fibre air intake ( very strong to stop it from imploding from the vacuum created by the intake pressures)
The electronics could not be over come using the Boxster ECU , so a 3.6L ECU was installed and then customised to the Boxsters wiring loom. It means I now can't open the rear boot using the key fobb ( oh dear ,what a shame, never mind!)

But, what it does mean is that I have 329 BHP, 0-62 mph in 5 second (996 has the engine over the rear wheels and therefore gets better "off the line traction") 0-124mph in 15 seconds and so far an indicated top speed of 179mph (wife started nagging).
The main advantages of coarse, are not it's dragg racing capabilities, but the shed load of mid range grunt you get, just face burstingly fantastic for the mountain roads around Barcelona and up over the Pyrenees and into France....... Magic!

TISPKJ · Jul 14, 2004

NICE .............

If my numbers come up saturday maybe the factory can put the GT3 lump in for me ........... then again why stop with only 380bhp, sod it stick a new GT2 lump in ............ bye bye everything

Regards

Mark_Bennett · Jul 15, 2004

Ruf have already put a GT3 lump in a Boxster (a black one, lives in London).

I guess it must be sorted by now. I'm sure they will be happy to do the same for you...[8D]

Richard Knight · Jul 15, 2004

Wow
A GT3 lump, now that would require alot of thought to strengthening the, gearbox ,clutch and driveshafts plus additional cooling of both oil and water I guess.
Mark , are there any articles anywhere relating to the RUF conversion ? I would like to see those!

Cheers Richard.

Mark_Bennett · Jul 15, 2004

Not that I know of[&o]

I saw the car under construction last year at Ruf. And someone else on the board told me it was owned by an aquaintence of thiers in London. (Pure co-incidence!)

If I can get over to Ruf next weekend (they are having a BBQ for PCA members) then I'll ask more[

]

Grant · Jul 15, 2004

Blimey, a 3.6 in a Boxter, sounds great, but surely the only trouble is it ends up costing you more than a 996cab (before we talk about re-sale depreciation on a modified car)?
Do tell !?

Mark_Bennett · Jul 15, 2004

There's more to it than fiscal reasoning...[

]

Richard Knight · Jul 15, 2004

The cost
Well the fully loaded Boxster S, leather ,lights, sound, sports suspension,wheels,silver bits, etc was 40 sterling ( back in 2001) ,

To further modify the suspension i.e lower another 10mm (change of springs). fit and install the 3.6L lump,complete stainless exhaust system, change rear lights to smoked grey,and fit 20mm spacers ( subsequently the wheels have now been changed to the Turbo hollow spokes from a 993 turbo) was about another 12k sterling.

Total 52k sterling. I think that just about buys you a bogg standard C2 complete with 17 inch rims and a plastic dash!!

N.B. On the attachment you can see the custom, carbon fibre air intake running from the 9 o'clock to about 12 o'clock position.

But a big thing to consider is once you've done all this, you don't have that peace of mind that the car has been tested for millions of mile in all weather conditions etc.

As for resale, well your guess is as good as mine.