sergiomartins

Well apart from the airfilter choice and the sparkplugs, i dont think would account for 20 or so Hp missing, so im trying to narrow it down to :
1 variocam solenoid not working all the time.
2 variocam tensioner not holding oil pressure when activated (downwards movement)
3 camshafts not timed right

Now the flaw in this line of thought:
1 wouldnt the solenoid not activating send a code to the DME? i have no error codes.
2 the tensioner not holding the pressure is a longshot cus ive seen it holding air pressure when timing the cams before.
3 the cams were timed by a porsche specialist, this guy was responsable for tuning 968 racing cars a couple years ago, 968 GVR Team in the uk.

The only way now is to do a dynorun in the same Dyno as before, and do a proper run up to 7000.

any more ideas?
cheers

968norway

The variocam reverts to 'normal' around 5000 rpm, so it is not a factor at the top end, that is the bump in the standard power curve in the manual. IMHO, you may have problems with it, but the missing hp comes from somewhere else. I mentioned the MAF before, I had a similar problem, missing hp on a dyno. There were no error codes, changing the MAF resulted in a noticeable improvement, on the 'butt-o-meter' at least.

Correct camshaft timing is also essential, the method in the manual is not accurate enough. The TDC needs to be located precisely.

Have you disconnected the variocam and driven the car?

Eric_Oz_S2

As mentioned elsewhere here the Variocam has no (or very little) effect on power above 5500 rpm - so I doubt that would affect the peak power you are concerned about.

Suggest you check the hall sensor and knock sensors as these can retard ignition by 6 degrees if faulty.

So does the K&N increase power or the airbox mod (presumably you mean drill big holes in it)? I removed my K&N from my S2 and put stock back in - can't say I noticed any difference.

Fox944

It is a combination of both. The drilled holes are the key to the airbox modification. The k&N filter allows you to get the most out of it, as the filter itself flows better then the oem filter.

As for seat of the pants, you arn't going to feel a difference. The difference with just a change of filter is so small, that you would not feel it. a 30 degree change in outside temperature would have a bigger effect on power.

Also, compared to a 968, a 944 S2 will respond differently to modifications. 968's have Vario-Cam, a dual resonance intake manifold, and different exhaust plumbing.

sergiomartins

Heres some pics of my Airbox and the Bored TB.
Update on the missing hp, after changing the solenoid for a new one, also changed the oil from 5w40 to 10w50. The rattle is gone
I also order a new MAF so until it arrives on thursday, then i gonna dyno again.
Also changed the chip to Promax 7700row.
Drivability seems better.

nick_968

Where did you get the bored out TB and how big is the new internal diameter?

sergiomartins

The TB bore was a DIY job, bought a 2nd hand one from ebay, n gave it a try, with a pilar drill and a 65mm sander on the end. its a very extreme bore if i was to do it again i would stay with in 68mm to 69mm, mine is 72mm.
Also cut the shaft that holds the butterfly plate in half and polished the best i could with a dremel tool. inc the new screws and knife edge the plate itself. The diameter of the butterfly plate is unchanged cus i couldnt replicate the plate in the new diameter. also only the intake side is bored to keep velocity of air thru the TB into the intake.
These pics are work in progress, not the finished job.

PorscheDude1

Have you checked the throttle cable?

It coukd have stretched a little over time and not allowing the buuterfly to fully open.

savvas944

hI there , i just thought of sharing some info.
it seems that the proplem is the overboring of the , throttle body, which allows now fully open about 50% more air into the engine, in theory , without any addition of extra fuel, even with max chipping the std injectors max out. the promax 7700 row are a good addition but again max flow has been reached.

another strong possibility is that the overboring at 72 mm from the std 60 mm, has caused a drop in airflow velocity, at the narrowest point , to the point that the resonance tuning of the elaborate manifold
went south, and instead of more air been passed from the trottle, in reality is less,. Bernoulli principle and that sort of thing.

additionally the cams ,perhaps have increased overlap which can push the peak power up the rev range
but ,if the air fill velocity has dropped, they do not contribute at all to the power.

In my search for more power, i have experimented gradually with a larger throttle plate , each time up
one mm and found that 63 mm is the max that can be tolerated, which translates to 11 %more air ,
and with a minor fuel pressure increase, the original design intent of the manifold, is not altered.
the addition of the promax chip enchanced the 3 mm bore increase, also .

if i were you i would install the original throttle body back and run it again.You may be suprised.
An adjustable FPR ,

Moook

Serjio.
Did you do ALL the mods yourself.?? Or buy the car with it all done, As i remember a car VERY similar recently sold on E-bay.???
I would also recomend you took the car + get it LIVE mapped. As you need everthing to work in unison with each other.
The correct fuel air mixture, cam timming ,, etc etc etc
I had a few "mods" done to my car recently.. I then took it to Wayne Jackson in the North West [I see your in the UK],,+ he live mapped it for me.. What a difference from before to after. It didnt increase the BHP much, BUT the drivability is GREATLY improved...
It now feels like ALL the horses are pulling together, not fighting against each other...
Trust me. Its well worth it over a generic chip....As the "generic chips" cant account for the extra mods the car has had done...

PS, Another thought. You say you were having rattling occasionally. This could be caused by the oil pick up pipe in the sump cracking, + sucking up air.. The variocam unit will then NOT work correctly as it wont have enough oil pressure + worst case the cams will wear out prematurley....

300guy

If you have made your throttle body flow a significant amount more then the question is - does the DME account for engine load during WOT. I seem to recall that the fuel correction map WOT is a 1D map (as in RPM only, not RPM and engine load). If so you could be leaning the engine out.

If you're going to have fun with constant improvements and tuning then perhaps you should invest in a wideband O2 sensor. Get one with datalogger. It makes it possible to review the data and they usually have auxiliary inputs so you can datalog other engine sensors (knock, MAF, oil pressure, etc).

What is the update with your car?

Damian in NJ

NZ Mike, back in the early days on .net, did the extrude honed throttle body, higher fuel pressure, and lost hp as I recall.

SpeedBump

bored throttle body can make horsepower depending on other mods done to the car, at least on mine. Don't remember the numbers but it did show gains.

AZ968Cab

That explains why Jack at Stuttgart SW took mine out and replaced with copper on my last service (those IR plugs are like $11/piece...). It must be a placebo affect but I swear I felt a difference (chirpier in 2nd) after putting them in my S2 cab.

I did prefer the K&N 10" cone in my vented nose panel on my S2, cooler and more flow in front of the radiator.