8v Engine Tuning

[barks944]

So I got my car on a free dyno run the other day courtesy of Powerstation in tewkesbury.

My 1984 2.5 8v produced 148.4HP and 160lbf/ft. Pic of the dyno printout is a bit blurry from my phone but you can see the results if you zoom in.

http://picasaweb.google.co.uk/tomspics1234/944Dyno#5274910186676501474

Now im looking at tuning the engine and I was thinking first about changing the cam's and sorting out the DME with a late model+AFM and a remap. Im not looking to build a race engine and the car will be my daily driver so I would just like some more top end power and possibly a higher rev limit.

Can anyone confirm what the cam overlap is on my 944, I've heard its about 3 degrees. The dyno results show the car produces peak torque from about 2k rpm which along with the power drops off about 5k rpm. This would suggest to me that the gas flow is becoming an issue at higher rpm's. Any experience with changing the cam's would be appreciated. Im aware I will have to sacrifice some low end torque for this if I go down the cam route, and prob some economy. Any suggestions on how much overlap to use? I have an original cam I was thinking i could get re-ground.

I understand the early DME's do not have an EEPROM so cannot re-mapped. Fortunately I have a late model DME and AFM avaialble to me which from what I can tell can replace the parts on my car allowing it to be re-mapped. This would seem to be the easiest course of action, however I was wondering about aftermarket management systems. I would imagine this would be rather expensive to implement compared to a free late DME+AFM. Would it yield any sigificant benefits?

Cheers

Tom

 

[Panzer944]

I'll be returning to the UK in Feb/Mar next year from my sojourn in Belgium and will give Powerstation a visit (I live in Worcester) with my 1986 Lux with 165K miles on board ... now, reading your e-mail - and not knowing diddley squat about injection systems - does it mean that my car ("oval dash" 87 year model) has some latitude ... in terms of tuning ... for what used to euphamistically be called 'fast road' spec? I remember from my simple mini tuning days (nostalgia's not what it used to be!) where a cam and carb made a significant difference ... but the received wisdom for this engine seems to be 'leave alone' ...

 

[944 man]

1985 series one ECUs can have the chip fitted, same as the cheaper series two-type ECUs (these are quite rare though). Good luck finding a camshaft that costs less than your car is worth!

Dont expect to improve the cylinder heads; its the manifolds that restrict the engine: as well as the primitive ECU. Id be looking at careful matching of the inlet and exhaust manifolds to the ports on the head and replacing the aged Motronic with a MegaSquirt.

Simon

 

[944 man]

MegaSquirt shouldnt be expensive at all, even after the fall in the pounds value. If you can 'live' map the EEPROM in a series two (not to be confused with a 944 S2) ECU, matched to a MY'86> airflow meter as you say, then that may be cheaper. Personally Id fit a refurbed set of late type injectors too.

 

[barks944]

when you say live map the series 2 lux do you mean real time map adj on the dyno? i was under the impression you couldnt do this. seems like its a case of dyno,renove chip. flash chip. reinstall chip. dyno. seems pretty labourious. other option would be to use a pre tuned chip.

interested in megasquirt, im a control systems engineer so this is somthing i would love to have a play with.

it was mentioned that a new cam would be rathe pricey, well i mentioned i have a spare cam. is getting one modified expensive? i have a file at home.

how big an effect would poorly matched manifold have? im guessing its relative to the engines power. what would be a possible figure on my engine? l5 -10 hp?

 

[barks944]

Ive just been reading about megasquirt and it sounds awesome. I want to get one, has anyone had any experience fitting these to the 2.5 8v? It doesnt sound too hard as most of the sensors are there. I guess I would need to fit a O2 sensor. Theres plenty of vacuum pipes I could use for the MAF. What about the AFM on the 944 can the megasquirt interpret the output signals from it? The 944 has an idle control valve doesnt it? Is this somthing the megasquirt could deal with?

 

[Diver944]

ORIGINAL: barks944

when you say live map the series 2 lux do you mean real time map adj on the dyno? i was under the impression you couldnt do this.

It has to be an oval dash car or later as they have removable Eprom chips. The tuner basically spends a few hours with your car on the dyno adjusting the fueling and timing throughout the rev range and at full and part throttle to completely customise the settings to your individual car.

Peak gains will not be huge ( mabe up to 5bhp) but there will always be a useful gain throughout the rev range and the car will run smoother. For instance your actual peak power at 6000rpm may be the same but if you have an extra 15-20bhp at 3500rpm through to 5000rpm your car will be faster

Whether it is worth the several hundred pounds cost for such a small gain is purely down to personal preference

 

[333pg333]

I know there's a few guys that have played around with Megasquirt in the US. Best to search in Rennlist. My friend has a pre Oval dash n/a and he put in a different cam that was a Porsche part. I can't remember exactly what cam it is, but it has livened his car up somewhat. I could find out. I think he even dyno'd before and after.
This is another interesting site. Mostly for turbo's but you might find something in here.
http://members.rennlist.org/951_racerx/
EDIT: Looks very 951 oriented, but no harm to look inside.

 

[barks944]

ORIGINAL: 333pg333

I know there's a few guys that have played around with Megasquirt in the US. Best to search in Rennlist. My friend has a pre Oval dash n/a and he put in a different cam that was a Porsche part. I can't remember exactly what cam it is, but it has livened his car up somewhat. I could find out. I think he even dyno'd before and after.
This is another interesting site. Mostly for turbo's but you might find something in here.
http://members.rennlist.org/951_racerx/
EDIT: Looks very 951 oriented, but no harm to look inside.

If you could find out that would be greatly appreciated.

 

[Panzer944]

Found this on the net ... camshafts for 944 n/a and turbo (and others)

http://www.jmengines.com/camshafts.htm

If they are already known about - my apologies! If not, their claims look quite ambitious/interesting ... not least given the apparent limitations for tuning this engine. Anyone heard of them?

 

[944 man]

I certainly hadnt seen that before. As I mentioned earlier though, some series one ECUs have a socketed EEPROM, but they arent particularly common. Mine does have one, but its a very late 1985MY car.

 

[sawood12]

Power gains is all about air flow. The more air you can flow through your engine the more power you'll get - it's as simple as that. Attention to the cylinder head, manifolds, intake etc will all give you small incremental differences that should add up to a noticeable end result. Just simple back to basics engineering. One of the first things to do is to ditch the AFM, which is a huge restriction, and go MAF.

You need to take a holistic approach rather than just chipping away at the external parts. It is often the case that you can only really unlock the potential of one improvement once you've addressed all the other areas of the engine - i.e. no good modifying the intake unless you see to the exhaust - and so on and so forth.

Question is though - how much can you really expect? I'm sure your investment to return ratio wont be huge. It might just be simpler and cheaper to just go Supercharged and be done with it.

 

[944 man]

I wonder how realistc the quoted returns are for those camshafts? As I have stated previosuly: the inlet and exhaust manifolds can be improved, but the head is very good already. The inlet tract is the cars weak point, along with the primitive engine management. If you address those issues then the cam should really reap the rewards.

Simon

 

[944 man]

Scott: I was arguing that a holistic approach should be taken to chassis modification in the contentious 'cage stiffening' thread, but I gave up after a while (without mentioning it by name).

 

[edh]

I don't know if you can still get JME products - I read he'd retired. They will probably cost you more than the car's worth []

I'd look carefully at getting everything in good order first - renew ignition components, fuel filter (often ignored), and try a chip (stuff like blitzchips are very cheap)

Would you really notice an extra 10hp in a road car? - I understand why people spend £££ on a race car to eke out the last few % of performance, but there are diminishing returns for every pound spent. How much would it cost to build a 180-190hp 2.5 8V?

The best way to get more power is to drop in a 3.0 16V - maybe not so easy in a early dash model though. It might sound expensive at first, but you'll be getting much more power & torque than you will ever get from a 2.5 8V.

Then again your cheapest route is to buy a faster car (or go the lightweight route if you can live with it)

 

[sawood12]

ORIGINAL: 944 man

Scott: I was arguing that a holistic approach should be taken to chassis modification in the contentious 'cage stiffening' thread, but I gave up after a while (without mentioning it by name).

I don't think anyone was disagreeing with you on that one in that a fully welded cage tied to the suspension is the ultimate route, I thought the debate was more centred around how much stiffening a bolt in half-cage would provide. Anyway, not wanting to digress.

If 944 Man is right about the head being good then it should be a case of exhaust and intake mods to get a benefit. But just how much remains to be seen. It will be interesting to see what gains Peter Empson gets from his supercharger. Of course another option that is relatively cheap is Nitrous.

 

[barks944]

Im thinking that if i get a new cam for say 2-300 and put a late chipped DME that should give some pretty reasonable performance gains for the money. Ive got the late DME and AFM, so its rlly down to the price of the chip and camshaft. It doesnt seem like a huge amount to spend. I think there rlly are some gains to be had from the cams.

If you look here http://members.rennlist.org/951_racerx/CamProfiles.pdf

You will see the cam for the 944 has no overlap and from what I know about cams (not a great deal tbf) that's more the profile of a tractor or land rover than a sports car. This is what leads me to believe there are real gains to be had with this engine. If I can get some decent gains from a re-mapped ecu and combine that with the gains from a new cam and some of the other smaller modifications recommended the car should get a pretty reasonable increase in performance for the price. I'll do the work myself, except for the cam work and possibly a re-map if I don't just get it chipped.

As for dropping in a new engine, well I dont rlly want the complexity of the 16v, as for a supercharger I don't think I could live with the economy.

I don't want to buy a new car as I've invested time into this one and I cant rlly afford to insure (23 yrs old, im 3rd party on this one) or atm buy, a car of any significant value.

Plus I've never tuned an engine before so I'm quite interested in the process as well as the results.

 

[barks944]

So I'm getting the impression the intake tract is a major weak point so I think this might be my first port of call.

So if I want to get rid of the current AFM and replace it with a MAF sensor then what needs to be done with respect to the DME. A MAF sensor is different in what it measures to a pure AFM so would it require a new DME? Or would a remap be sufficient? As well as what it measures there would prob be a difference in the sensor signals, that could be sorted with a signal transmitter of some sort easily enough. Any suggestions on make/models?

 

[sawood12]

Well there is a MAF product called SciVision that you can get for an S2 so I don't see why it can't be made to work for your car. This is a product made by the guys who originally were involved in the development of the Bosch motronic systems in 944's (the EPROM types) and is a 'plug and play' setup that does include a new DME and KLE chip. You can get them from Promax Motorsport, but as I said i've only seen them advertised for turbo's and S2's, but if you say your's has an EPROM type ECU it might be the same Bosch Motronic system as an S2 so a simple re-map might be all that is required. Worth a call to Promax at least and they can contact the manufacturers.

 

[barks944]

Im wondering if I could get a second hand MAF sensor from somewhere and design a transmitter chip that could convert the signal to one understood by the standard DME. I also thinking that you could connect an 02 sensor to the same hardware and set it up as a compensator to get you a desired AFR.