996 3.4 on Track Days

So I've got the itch to throw my 996 around Brands this summer. Not taken the 996 on track before, always used cheap cars like MX5s or MR2s. Anyone else here track their regularly and if so what have you done to protect the engine? Mines a M96/02 - 3.4L I hear horror stories of rod bolt failure, oil scavenging problems, but I'm guessing a handful of laps and cool down will stop the oil aeriation issues and keep the viscosity up. Thoughts?

have a read of this http://911uk.com/viewtopic.php?t=31565

Get an X51 baffled sump from your OPC 👍

If you haven't seen it, watch this. MC

Just make damn sure you put in the highest boiling point brake fluid you can find. Boiled brake fluid is the No.1 cause of a limited number of laps on track days for 996s.

That's a great post.

Yes, regularly. The answer is how much do you want to spend? Being sensible I would start with.., FVD Motorsport Sump - This holds an additional 0.6 litres of oil and is fitted with an X51 baffle. (There was one for sale in the classifieds) Low Temp thermostat. 997 GT3 brake Ducts front & rear. High temp brake fluid (Castrol SRF, Motul RBF660) Good luck :thumb:

I'd put all the X51 oiling mods on there if you can get them (and beware the dual stage pump that's currently in production, it pumps the wrong way). The FVD sump is a good shout - it's very little money in the scheme of things and as Crash says, holds an extra .6l which is handy. If you read the Streather book he references an endurance/motorsport X51 sump that has a greater capacity, with the FVD could well be a straight, erm, homage to. Also, to those who know, the towel rail marks the motor out.

Hi, I've found the 997 GT3 rear Ducts easy enough, but bit confused about which front ones to order.. There's some very cheap ones about 3 quid each on design 911 they look only a little different to the ones my car comes with, are these correct? Or is it the Cup Car ones you meant? Also the 997 Turbo front ones look absolutely huge and probably a good punt too? Thoughts?

Screenshot of shopping basket online.. Just checking?

Is it just a one-off or will it be a regular thing? I've taken mine on the occasional track day and apart from keeping an eye on tyre pressures have done literally not a thing to it - it's coped absolutely fine. So unless you're planning to hammer it on a regular basis I'd suggest a stock 996 will be quite happy to go round Brands a few times. It is, after all, sort of what the cars are built to do.

Stock there are a couple of areas that can give cause for concern, under specific conditions. The scavenge pumps in the heads are powered from the exhaust camshaft, and as the heads are opposite orientations to one another (bank 1 the drive end of the cams is toward the front of the car, bank 2 the drive end is at the rear of the car) you have the potential for imbalance. Under heavy acceleration the oil will run toward the back of the engine, which means that the sump in the head of bank 2 is filling up nicely, and the standard single stage scavenge is returning oil to the main sump very nicely. The sump on the head of bank 1 will see a slightly reduced filling rate, but this doesn't seem to be a problem - the ~280ish bhp that our cars have doesn't generate enough G under WOT to empty the sump in the head. This changes under braking, where our cars can generate much higher forces, and also under cornering - so the nightmare scenario for our cars is heavy braking followed by a long left hander, as the oil will be pooling in the front of the head on the right hand side of the engine, with the scavenge pump in the sump at the rear of the head drawing on (potentially) nothing. The stock (main) sump also has fairly average baffles, which allow the oil to run from one side of the sump to the other, evading the doors in the central baffle that are meant to keep the oil central and therefore the main oil pickup submerged. The "integrated dry-sump" which Porsche talked about when they describe our engines refers to the plastic "tank" described by the plastic baffle, the intention being that when turned off the whole sump fills with oil as it drains from the engine, but when the engine is operating the majority of the oil is kept within the "tank"*. So in our long left hander scenario we have oil pooling in the right hand head and not being returned, and what oil there is in the main sump pooling against the right hand side - it's not hard to see that we're now dangerously close to the main oil pickup sucking air/oil rather than oil - or only air. This might be for a fraction of a second, but that's enough to interrupt the oil supply to the main bearings, and if you do that a few times (or once, with enough ambition) you'll spin a bearing and that's the car on the back of a transporter. Porsche knew this - the X51 kit addresses the problems. Firstly the right hand head has a dual stage scavenge pump fitted, which scavenges the front of the head via the iconic towel rail hard-line. This stops long/fast left handers being so dangerous to the car, and when paired with the X51 sump which has baffles that fully seal against the inside of the sump and therefore stop the oil escaping the central "tank", which is now much better suited to that description. See Mister Corns excellent video for the details. *Bear in mind that the MA1/MA2 run an evolution of this design, and they don't go boom, so it's fine when done correctly.

So the Indy Circuit at brands is majority right hand turns, there is the braking zone after Druids down to Graham Hill Bend which might be a concern, but probably not too bad. Obviously the basic prep, racing fluids, brake pads and a decent set of boots are needed for any track day. I'm most concerned about this oil starvation issue which has been highlighted in the last post, the X51 baffle can obviously help but I don't see anywhere selling the X51 head pump anymore. I'll grab the brake cooling ducts, Christ alive they're not expensive and if they help keep the brakes from fading that's a bonus. This is an occasional thing, but I've not had the best of luck with M96 engines.

So having done the math, it makes a lot of sense. We're looking at the potential of the engine which is known to be around 0.8G before the oiling system can give up the ghost. Our cars accelerate at around 0.57G so there's no issue there, laterally they can peak at around 0.9G in stock form, perhaps a professional driver can sustain it there long enough to starve the engine but highly unlikely as you said the scavenge pump is being fed just fine. But we can decelerate at around 1.3G then pull straight into a 0.9G left hander, that's going to starve the scavenge pump on bank 2 (cylinders 4,5,6) quite easily in the hands of a professional driver. Makes a lot more sense to me now, think that X51 pump is really quite necessary for the X51 baffled sump to really make the difference it was intended to make.

Keep your eyes peeled for more info on x51 scavenge pumps from Dammit or myself in the next month or so.... MC