Supercharging?

[appletonn]

My dad has just bought a second 924S to play around with with a view to doing a few trackdays with it eventually.

I'd still rather go down the route of putting an S2 or 968 engine into a 924S (much lighter than 944) than the supercharger route and you would still have the sleeper effect.

Then you could supercharge the 968 engine, as Peter has done....[]

 

[Big Dave]

I thought Petes car was a S2 engine.????

 

[mr brightside]

ORIGINAL: 944 man

Wise words from Paul. MS isnt expensive though, in fact, even at the current miserable exchange rate its cheap. Sensors cost a few pounds and youll end up with a far more modern and able system (with more power from standard too).

I like the idea of better management even if i don't go through with the charger idea, does the system get rid of the barn door MAF or keep it? Have you got a link to a dealer/installer in the north who knows what they're doing? Google just gave me a load of rubbish!

 

[mr brightside]

ORIGINAL: appletonn

I'd still rather go down the route of putting an S2 or 968 engine into a 924S (much lighter than 944) than the supercharger route and you would still have the sleeper effect.

I'd then be in the situation where i had an engine i didn't know intimately, i don't really have the connections to source a 100% good one and would probably end up with something that was worse than what i have now. Peace of mind in knowing my current lump is valuable to me.

 

[appletonn]

ORIGINAL: Big Dave

I thought Petes car was a S2 engine.????

Sorry Dave, you're quite right - brain fade on my part!

 

[Diver944]

The current Speedforceracing offering for the 2.5 N/A comes in at $4600 US and includes a MAF conversion with laptop programmable fuel delivery and talks about 182HP at the wheels (so circa 210bhp at the flywheel). This is the base version at 6psi without an intercooler

http://www.speedforceracing.com/index.php?productID=1028

 

[Tam Lin]

$4600 sounds like good value: You get the same power as an S2 engine conversion (which costs more), and if the 2.5 NA mill goes bang, then they're not exacly expensive to replace..

Looking at that dynosheet, is it me or is that a bit weird for something with a mild 8V cam?! Odd that BHP keeps going straight up without any plateu to 6100 rpm. In which case, bit of an odd speed to cut the power run.

 

[Diver944]

I thought that's the way all superchargers worked? Basically the blower is connected to the crank so the faster that the engine turns the more boost it makes, peaking at peak revs. Does look like they stopped that run a few RPM short of the redline though (maybe the Rev counter in the car was over reading comapred to the Dyno's measurements [&:] )

 

[JamesO]

ORIGINAL: mr brightside

ORIGINAL: 944 man

Wise words from Paul. MS isnt expensive though, in fact, even at the current miserable exchange rate its cheap. Sensors cost a few pounds and youll end up with a far more modern and able system (with more power from standard too).

I like the idea of better management even if i don't go through with the charger idea, does the system get rid of the barn door MAF or keep it? Have you got a link to a dealer/installer in the north who knows what they're doing? Google just gave me a load of rubbish!

MS is pretty much DIY only as far as I know.
You can ditch the AFM, I modified my air box so a straight bit of gutter pipe replaced the AFM.
You would use MAP (manifold air pressure) and it would be a good idea to fit a proper throttle position sensor as the 8v na is just an idle/full throttle switch.
The ms comes in at around £300 and you really need a wideband o2 sensor which is around £250/300.

Edited to add: These boys love megasquirting 924's

http://www.924board.org/viewforum.php?f=4

This site can be quite helpfull. I quite fancy the in dash lcd display at some point.

http://www.diyautotune.com/

 

[sawood12]

ORIGINAL: Diver944

I thought that's the way all superchargers worked? Basically the blower is connected to the crank so the faster that the engine turns the more boost it makes, peaking at peak revs. Does look like they stopped that run a few RPM short of the redline though (maybe the Rev counter in the car was over reading comapred to the Dyno's measurements [&:] )

There are two types - one uses the same type of compressor you find on an exhaust driven turbo - this delivers varying boost according to RPM just like a turbo. The other is not really a compressor at all but is really an air pump which just pumps air into the intake system and the compression of the air occurs throughout the entire intake system and I think these deliver a more consistent level of boost across the whole rev range.

 

[bertelli_1]

This is right up my street! I've been playing with ms and forced induction for years (check my website if interested - conrod.co.uk) including lots of work on Golfs, similar bosch system to the 944. Running an aftermarket ecu enables much more accurate tuning of your engine than the old and slightly antiquated bosch system fitted, efi has moved on a lot in the last 20 years. A modern ecu will generally use throttle position and manifold pressure (or maf) for calculations so a linear tps would be needed (tps can be switched off in some ecu's including ms). The biggest hurdle getting a system to work on a 2.5 944 (na & turbo) is the crank trigger as Porsche & audi used 2 sensors which aftermarket ecu's cannot decipher. The 3.0 engines (s2 & 968) use a common 60-2 trigger and a single sensor, this setup is still used today & works with all aftermarket ecu's. You can choose to fit an extra trigger wheel and sensor to the crank pulley & ignore the stock setup (the Ford 30-1 trigger wheel is commonly used). And yes, the airflow meter can be thrown in the bin, the ecu will not need a signal from it. You also have the option to ditch the distributor cap & use a coilpack or even individual coils which can give a much better spark and improve reliability.

As for superchargers, there are 2 main types, centrifugal & roots. The centri ones look like half a turbo & deliver boost that increases with rpm. imo they are a bit crap & don't suit most applications but give big dyno numbers at the expense of driveability (nothing at low revs, scary quick at high revs, think tuned 944 turbo but worse lag). The roots type are generally bigger and offer decent bhp gains at lower revs but not the pub bragging dyno figures. Thier larger size can make some installs tricky though so most conversions use the centri type.

Whilst I'm rebuilding my s2 I've been eyeing up a few of the mods outlined above & have some ideas which I think will work rather well on the engine, maybe even a simple 'plug & play' ecu.

 

[tr7v8]

OK couple of points. The Mini M45 is too small for even a 2.5 let alone a 3 L.. The M62 is better but far too big to go under a 944 bonnet without lots of grief I have one here if someone wants to buy it.
My project was an S2 lump with a Vortec V5G, boost is entirely dependent on how it is set up, in theory it will be top endy but as it is effectively 1/2 a turbo it needn't be as per a Turbo!
Could be interested in selling both the S2 lump, a generic mustang bracket as a pattern & the S2 lump if someone interested, separately or together..
Pics of it dummied up here :-http://www.pbase.com/tr7v8/944_sc_project

 

[bertelli_1]

Yes, the eaton m45 is designed for sub 2.0l engines, the m62 for 2 - 4l engines, however, it is a bulky item. I'm not sure what Mercedes used on their 230 kompressor but they also have a clutch on the pulley to disengage the charger. One thing to bear in mind is the size of the 944 inlet manifold - its huge! With a custom manifold there is plenty of room to fit any supercharger you like, example below -

 

[sawood12]

ORIGINAL: bertelli_1
The biggest hurdle getting a system to work on a 2.5 944 (na & turbo) is the crank trigger as Porsche & audi used 2 sensors which aftermarket ecu's cannot decipher. The 3.0 engines (s2 & 968) use a common 60-2 trigger and a single sensor, this setup is still used today & works with all aftermarket ecu's. You can choose to fit an extra trigger wheel and sensor to the crank pulley & ignore the stock setup (the Ford 30-1 trigger wheel is commonly used).

The most common method to get around this on 944 turbo's is to use a trigger off the cam shaft. Works well from all accounts and easy to install. Some have installed trigger wheels onto the flywheel also.

944 turbo's already have a Throttle Position Switch in the stock setp - the biggest draw back of the 944 turbo's system that modern ECU's have is the AFM instead of MAF/MAP and a fairly crude ignition mapping setup that is not sensitive to manifold pressure. Other than that the EFI system on the 944 turbo has been proved to be surprisingly capable compared with modern stand alone setup's with fairly minor mods - typically case in point is the Vitesse setup which, for a few thousand quid and a few hours of install and setup, really delivers about 95% of what any aftermarket ECU setup can deliver unless you're incorporating other features like fully sequential firing or water injection.

 

[944 man]

Megasquirt doesnt cost anything like 'a few thousand quid' though: thats the beauty of it... It is isnt a plug & play solution of course, but James has already done the hard work, so itll be far easier for anyone else following.

 

[JamesO]

ORIGINAL: bertelli_1

This is right up my street! I've been playing with ms and forced induction for years (check my website if interested - conrod.co.uk) including lots of work on Golfs, similar bosch system to the 944. Running an aftermarket ecu enables much more accurate tuning of your engine than the old and slightly antiquated bosch system fitted, efi has moved on a lot in the last 20 years. A modern ecu will generally use throttle position and manifold pressure (or maf) for calculations so a linear tps would be needed (tps can be switched off in some ecu's including ms). The biggest hurdle getting a system to work on a 2.5 944 (na & turbo) is the crank trigger as Porsche & audi used 2 sensors which aftermarket ecu's cannot decipher. The 3.0 engines (s2 & 968) use a common 60-2 trigger and a single sensor, this setup is still used today & works with all aftermarket ecu's. You can choose to fit an extra trigger wheel and sensor to the crank pulley & ignore the stock setup (the Ford 30-1 trigger wheel is commonly used). And yes, the airflow meter can be thrown in the bin, the ecu will not need a signal from it. You also have the option to ditch the distributor cap & use a coilpack or even individual coils which can give a much better spark and improve reliability.

As for superchargers, there are 2 main types, centrifugal & roots. The centri ones look like half a turbo & deliver boost that increases with rpm. imo they are a bit crap & don't suit most applications but give big dyno numbers at the expense of driveability (nothing at low revs, scary quick at high revs, think tuned 944 turbo but worse lag). The roots type are generally bigger and offer decent bhp gains at lower revs but not the pub bragging dyno figures. Thier larger size can make some installs tricky though so most conversions use the centri type.

Whilst I'm rebuilding my s2 I've been eyeing up a few of the mods outlined above & have some ideas which I think will work rather well on the engine, maybe even a simple 'plug & play' ecu.

Yes on megasquirt you don't need the tps but it really isn't a big deal to swap to a linear tps, I used a 968 one as it was in my garage.
Ms can be made to work with the standard twin pick up on the 8 valve cars but it took a lot of fiddling to get it right. I wouldn't bother again as its much easier with a standard trigger wheel and as you say the 16 valve cars have a much more standard setup.
For my turbo project I will be controlling fuel only using the megasquirt for now, In fact its best to do that first anyway and once you have everything ball park then start messing with the ignition.

 

[mr brightside]

Hmm, this is getting technical. So with Megasquirt i can ditch my barn door MAF and use a manifold pressure sensor and a wide band O2 sensor instead, how does this tell the engine how much mass of air's going in or isn't it working off mass any longer? If it's going on pressure and density (?) does it have to be told the diameter of the throttle body or something? I don't like the sound of this farting around with crank position sensors and stuff, this is why i'd prefer to have it installed by a specialist Porsche tuning shop as i don't believe for a minute that it's as simple as it sounds, you fellas have obviously done this before!

I'm interested to learn my car doesn't have a Pot on the throttle body, i had to nip out with the multimeter and check to be sure! My 'fully open' contact closes about 15-20 degrees before the throttle is fully open...is this a problem?

Apologies for going off topic but hello to the guy in the black 968 CS who was at the Thieveley Pike fell race today, i noticed the PCGB sticker in your windscreen.

 

[Peter Empson]

ORIGINAL: bertelli_1
As for superchargers, there are 2 main types, centrifugal & roots. The centri ones look like half a turbo & deliver boost that increases with rpm. imo they are a bit crap & don't suit most applications but give big dyno numbers at the expense of driveability (nothing at low revs, scary quick at high revs, think tuned 944 turbo but worse lag).

As you'd probably expect, I must disagree quite strongly, but then I feel I am in a reasonable position to do so. Can I ask was it a S2 or 968 SC car you've driven and which setup was it running?

In my experience the centrifugal charger suits our cars perfectly, and retain great (in fact improved in my experience) driveability. I'd like to answer some of your points individually below:

-nothing at low revs -

hmm, at idle and below about 2k you're right, but boost builds quite quickly with revs and is doing really good things at 3k and over the power band any enthusiast is likely to want - between 4-6k - it's stonking.

- scary quick at high revs -

not sure the sub 300bhp I'm running is ever scary, but it is highly amusing in a light car, with overtakes being effortless. For the road I really don't think much more power to weight is required (not that it's going to stop me).

- think tuned 944 turbo but worse lag -

Total twaddle. Sorry, but it's unlike any turbo I've ever driven (noting that I've not driven a car with the very latest ball bearing turbos), there's instantaneous response available at any time, forget having to change down to overtake, it just goes. The power is consistent with rpm and the rush to the red line simply makes the car feel like a much faster tuned NA car, which is exactly what I want in a fun car.

So why not a roots? NA 944s of all variants (with the exception of the 944S of course) have great low down torque and the S2 and 968 are kings of this. The gearing/traction is such that it's arguable whether you really want any more low rev torque to keep it easy to drive on the road (and debatable as to whether the gearbox or engine will take well to it). A roots charger in my experience (on other cars, not a 944 - so I'm open minded) doesn't tend to give the feel of a true sports car, there's no 'on cam' type rush to the redline.

If you read my previous posts you will see I am not blinkered into thinking that this is the right choice for everyone, the cost alone to do the job properly will see to that, but I am having more fun than ever before. Of course if anyone ever wants to experience it and they're local they just have to pm me.

 

[Mike_Pollock]

Home now - I did take some pics of the installation -

and -

I think you can see the basics there.

Mike

Edit - I can vouch for the results of this installation, certainly in this vehicle and have been in a 968 around the same circuit.

 

[Hilux]

I'd say never modify a car when there is a faster version already in the range as done by the factory. It will cost you more in the long run, won't be anywhere near as reliable as the factory tested model and will be tricky to sell. The factory car will also probably have better brakes, suspension and cooling as standard to cope with the extra power.

Never a truer word said. All over the `net on loads of forums etc everyone whacks in more power without upgrading the important bits to handle it. However I do feel with the 2.5 n/a cars there is a law of diminishing returns. Ironically better brakes and suspension will make the car much quicker too.

Even so, its fun messing with cars and I`m a great believer in "will it work? If not I`ll make it work"

I know of someone who spent £50k on a westfield [8|][]