8v Engine Tuning
- Thread starter barks944
- Start date
edh
New member
for DME info, maybe you should start here...
http://www.frwilk.com/944dme/
I'm not aware of any homebrew MAF products that still use Motronic. The Scivision MAF is quite pricey & hasn't shown any great performance gains (although has provided improved throttle response). I think 911&PW had one on a 944 8V & it was a bit disappointing.
Megasquirt or similar is probably your answer. I would have a search through the rennlist forums for info.
http://www.frwilk.com/944dme/
I'm not aware of any homebrew MAF products that still use Motronic. The Scivision MAF is quite pricey & hasn't shown any great performance gains (although has provided improved throttle response). I think 911&PW had one on a 944 8V & it was a bit disappointing.
Megasquirt or similar is probably your answer. I would have a search through the rennlist forums for info.
sawood12
New member
The voltage signal from the AFM doesn't have a linear relationship to the barn door. The barn door doesn't open in a linear way with respect to the airflow though it because as it opens there is less frontal area of the barn door exposed to the oncoming airflow therfore the door opens to a lesser extent as the airflow speeds up. Also the barn door is fully open at around 4krpm so above 4krmp the mapping works off RPM and throttle position signals.
The SciVision kit includes a computer that does a proper job of interpreting the MAF signal and doesn't simply massage the AFM signal. It works in conjunction with DME and KLR maps that work specifically with the MAF sensor computer to provide a more accurate signal throughout the rev range.
The SciVision kit includes a computer that does a proper job of interpreting the MAF signal and doesn't simply massage the AFM signal. It works in conjunction with DME and KLR maps that work specifically with the MAF sensor computer to provide a more accurate signal throughout the rev range.
Didn't 911 & Cayman World do a back to back on a Lux some time ago fitting a SciVision MAF, where it lost a little power? I think the tuner involved managed to rescue the situation and see a small gain by tweaking it, but it was small for the cost and the upgrade was a disaster from a bolt-on perspective.
morris944s2john
New member
LOL!
To add something useful to the thread, I think you have to improve everything to see more power- i.e inlet, MAF, freer exhaust.
As said above you can't just change the cam and a chip on a 944 and it suddenly goes like a rocket. much development and testing is needed on your car by and expert which will not be cheap.
Might be better off selling the lux and buying a turbo or S2 or just going nitrous which is the cheapest way to get more power (in bursts!).
Peter Empson
PCGB Member
Sounds similar to my experience, we 'lost' nearly 5bhp with the MAF on its own on my car (Rollers of Truth mk1, both runs on the same day a few hours apart), but the difference was so small that I'm quite prepared to believe that it could just have been the dyno or its operator, the car certainly felt better for it. Promax then tweaked the setup, including a rolling road remap and we gained a reasonable amount of power (not that a power gain is the real benefit IMO, it's the increase in driveability thanks to the throttle response that transformed the car).
A good MAF sensor should respond to changes in air flow much quicker than the barn door meter thats currently on it. So like you say its the throttle response that should be improved as the DME will get the mixture more accurate. From a control systems perspective the AFM is introducing a large lag into the system i.e the airflow is not what the DME thinks it is. Therefore it will not get the mixture correct unless it has some way to predict and deal with it. By putting a MAF sensor in you reduce the lag and therefore get a better AFR when air flow is changing (during acceleration).
Its quite possible that you loose power because the DME is not setup to run with the increased accuracy of air flow measurement. Or simply the new MAF may not give the same voltage output as the original AFM at the same air flow. I.e your maps may become wrong when u change to the MAF. But like you say once it is re-mapped you get some gain, largely in throttle response due to quicker response from the sensor to changing air flow.
Edit: The more I think about it the more I understand the changes a MAF sensor will make and hence why people did not get power increases from installing them. I think that people have gone in with false ideas of what difference the MAF sensor will give.
A good MAF sensor is quicker to see a change in air flow than the barn door AFM. This means that once setup correctly your DME can track *changes*, not necessarily steady state values, in air flow more accurately than the original DME.
Increases in power from a MAF sensor come from a better AFR due to a more accurate measurement of air flow/mass. In cases where the original AFM is a bottleneck to gas flow in the engine you should see benefits from increased gas flow, but ONLY if the original AFM is the main bottleneck.
JME aka John Milledge is sort of the Godfather of 944 race motors in the US. Though I thought primarily turbo motors at that. His cams are very good in terms of construction. I'm 99% sure that they're made from Billet blanks rather than the welded onto stock cams like some other manufacturers. I have a cam done by the same guy who does the JME ones so I put my money down. It's almost identical in specs to the 2nd highest one on the turbo cams on the link. As far as lumpiness or driveability goes, it's absolutely fine around town and just loves the track! The difference feels like you've suddenly got a 16v head so much more freely does it rev.
As for my friend that I alluded to previously, he put in a later model n/a cam that model no. finishes in '09'. I believe it has higher lift and greater duration on the exhaust, but I'm quoting from memory....which isn't what it ever was...[
]
Diver944
Active member
His website states $650 US so with the current poor exchange rate, shipping, import duty and VAT you will be looking at around £620
I think you will really struggle to get some sort of performance cam for a 944 at around the 2-300 quid mark []. These are a low volume car and not many people tune the n/a 2.5 so there is no massmarket and therefore no economies of scale to keep production costs reasonable.
Roughly speaking you could pick up a good S2 with 210bhp for a similar amount of cash you'd spend modifying a 2.5 to only reach 180bhp at best. Kevin Eacock at EMC in Birmingham used to quote circa 190bhp for a complete race spec 2.5 rebuild but you'd be talking several thousand to get to that level .
I think you will really struggle to get some sort of performance cam for a 944 at around the 2-300 quid mark [
]. These are a low volume car and not many people tune the n/a 2.5 so there is no massmarket and therefore no economies of scale to keep production costs reasonable.Roughly speaking you could pick up a good S2 with 210bhp for a similar amount of cash you'd spend modifying a 2.5 to only reach 180bhp at best. Kevin Eacock at EMC in Birmingham used to quote circa 190bhp for a complete race spec 2.5 rebuild but you'd be talking several thousand to get to that level .
Right now I think Im going to give the following a go.
1. MAF sensor from some car, thinking honda or VW/Audi 2.0 and use a signal converter to give the correct range for the 944s DME.
2. Late model DME.
3. Match manifold to intake ports.
4. Chip/Remap.
This should cost maybe 200 if I search about/use ebay. And ill see where that gets me.
1. MAF sensor from some car, thinking honda or VW/Audi 2.0 and use a signal converter to give the correct range for the 944s DME.
2. Late model DME.
3. Match manifold to intake ports.
4. Chip/Remap.
This should cost maybe 200 if I search about/use ebay. And ill see where that gets me.
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