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My 944 Cabriolet


944s2cab
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32 minutes ago, OzJustin said:

I might take you up on your offer Timm, though it will likely be a fair way down the road. :)

It will be very interesting to see the gains on your 8v Turbo. Are you intending to do a before/after dyno comparison with the same setup? Are you expecting the driveability to improve substantially with the modern ECU control?

Yep, will definitely be doing before and after dynos. I'm expecting a large drive ability improvement for sure, especially once it's all tuned perfectly to suit my engine. I should also get some significant power gains once I get a better turbo and bigger injectors to support more boost.

 

Will be good to compare notes with you Steve once you've got yours up and running.

 

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11 hours ago, Timm said:

Will be good to compare notes with you Steve once you've got yours up and running.

 

Yeah, Hopefully mine will arrive before Xmas, that'll give me a few days to install, then rear wheel bearing, suspension, brakes etc, looks like I'll be busy

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  • 2 weeks later...

Right, VEMS VEMS VEMS,  Where do I start, first off, I've takn no photos to speak of, too busy focused on getting it done, 

Got everything fitted within two hours but I'd already spent some time making up the intake with temp. bung, O2 bung in exhaust,

First turn of the key , no go,  with Peep by my side via Facebook messages, Peep sent me a different config file, now it starts runs but doesn't idle, after 6 days of a little improvement here, a setback there I was seriously disheartened by it all and was thinking of sending it back (so pleased I didn't), turns out that it wasn't autotuning correctly certain cells due to a setting, once that was sorted, it is now mostly tuned and WOW!!!

A LOT more peppy, as soon as you put your foot down there's power, Id say at least 230hp, I know it's only my butt dyno, so I'm going to book it into a dyno run just as soon as Peep gives the tune the all clear

Just to make it clear, 

THIS IS NOT A PLUG N PLAY system-  it takes setting up, tunning, and in my case, fault finding, it has been a drama but well worth it

I'll take some photos once I've finished polishing the kitchen floorboards

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On 30/12/2017 at 12:15 AM, OzJustin said:

Great to hear it's up and running. I will be very interested to see the dyno result. Do you have a 'before' dyno by any chance?

Any more observations re the driveability? How is part throttle response etc?

I'm finding myself having to release the throttle because cars/objects are appearing faster than I thought, initial pickup is like night and day, gone is the second or two of sluggishness, to be replaced with near instantaneious surge in power, makes me want to go out now and go for a spin, if it stays where it is, I'll be happy but I think there are improvements to be had, finner tunning and a rolling road tune will optimize the potential of the system, 

The kit which Peep sent over is not without issues (loose vacuum hose inside DME, due to new type of hose fitted), loom adapter issue, but having Peep on hand with his expertise has been invaluable,

 

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Very encouraging!

Cab,

Did you go full stealth by fitting a gutted out AFM or are using a tube bypass?

Was the difficulty with the MAP port vacuum hose in the ECU housing come from reusing the old Motronic case or was it just one of those shit happens things?

How did you find Peep's harness building skills?

 

Keep up the good work!

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1 hour ago, Peter M said:

Very encouraging!

Cab,

Did you go full stealth by fitting a gutted out AFM or are using a tube bypass?

Was the difficulty with the MAP port vacuum hose in the ECU housing come from reusing the old Motronic case or was it just one of those shit happens things?

How did you find Peep's harness building skills?

 

Keep up the good work!

I've gone non-stealth, what with coil on plugs really giving the game away,

The MAP problem was due to being housed in the Motronic enclosure and Peep using a new hose which has a slightly larger iD, I opened it up and replaced it with some old vac hose i had lying around

Peeps harnesses are good, I gave a tug on the wires and one came loose, best to check, the TPS sensor was wired back to front (or the program was configured wrong) I solved by repostioning the pins but can be programmed in the config file,

Good thing is Peep is on hand most of the time and responds pretty much always within an hour or so

I was a bit dssapointed as in my naivity I thought I'd install, turn key and drive, it isn't and even without my problems there is steep learning curve

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2 hours ago, 944s2cab said:

I was a bit dssapointed as in my naivity I thought I'd install, turn key and drive, it isn't and even without my problems there is steep learning curve

How much time do you think you've invested in the conversion so far?

 

 

As long as the improved throttle response makes you forget those few hours of frustration pretty quickly!

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2 hours ago, Peter M said:

How much time do you think you've invested in the conversion so far?

 

 

As long as the improved throttle response makes you forget those few hours of frustration pretty quickly!

I suspect about 15 hours of steep learning curve, I was thinking along the way that it's good that I'm an Electrical Engineer otherwise I'd be F**KED

Yes the performance makes it worthwhile, I've still got to wire up and program the AC idle setting

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According to this screenshot at WOT 6K rpm injector duty cycle of 96%

Question for people who know, Does this mean I need bigger injectors? (I think I do)

Would be an indication of increase in power if I've maxed out the stock injectors!!!!

lo2wv_VfuQw7h1a_tSrvZzrXeiLYuL4Rj31cgpsW

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A couple of photos

Air temp sensor (supplied with VEMS kit from Peep)

B63r-qGjxxRRTxTLNfVeucPEPNIs3NmJFQQvqbkN

 

AFM bypass pipe, (keep natural or paint black?)

aGmCg14R2E0kH0zQBAUvoIKWscj9KPavmI1U-XeP

 

 

not much to see here!!!

IyrbbOqybKWSyyZ5N6Z6NpG3wRIAGmSZkJ1E7oX3

 

Got to paint the covers in their original silver colour

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Cam gear cover made from an old dizzy

Om3UGfTy8V0EP5rWskTQ7Q6yaTkOsBZmXZTZtd_p

Added small relay to convert 12v to Ground for AC idle up input, ordered an "on delay" relay to delay the compressor kicking in for a second so the idle has a chance to ramp before compressor load starts, this relay will go between the AC clutch and (stock) wiring connector https://www.ebay.com.au/itm/MINI-TIMER-SWITCH-TIME-RELAY-1-TO-150-SEC-KIT-12V-20A-Delay-ON-CAR-DAYLIGHTS/271066143155?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

aluNoWhamv5oijFNtILgOWX6NsvX0f9SazuGrd9s

 

Relay secured (later I glued it on as well)

SXn6alQtrdGuvvqepLK-nm2dqQJG1D5C__pQ3CFy

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Your photos aren't working again.

If that injector duty is accurate, and you're not running too rich, then yes you should get bigger ones. Definitely an indicator of a power increase though! Did you happen to do a 'before' dyno?

After I install my VEMS I can give you my rebuilt stock 951 injectors for cheap if you like. They flow a bit more than the S2 injectors. Peep says he's gonna post mine off this week. How long did your postage take?

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4 minutes ago, Timm said:

Your photos aren't working again.

If that injector duty is accurate, and you're not running too rich, then yes you should get bigger ones. Definitely an indicator of a power increase though! Did you happen to do a 'before' dyno?

After I install my VEMS I can give you my rebuilt stock 951 injectors for cheap if you like. They flow a bit more than the S2 injectors. Peep says he's gonna post mine off this week. How long did your postage take?

Postage is a long time compared with USA UK  etc. about 3 weeks

 I was going to upgrade to a Version III Bosch injector, gives a better atomised pattern instead of the standard stream with Bosch Version II, although some schools of thought say you get more power from liquid petrol entering the combustion chamber as there is more room for air?!?!?

Might take you up on the offer of your injectors though

What injectors are you looking at? if you look at all the online calculators, the 944 injectors are way too small for the HP they deliver

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3 minutes ago, 944s2cab said:

Postage is a long time compared with USA UK  etc. about 3 weeks

 I was going to upgrade to a Version III Bosch injector, gives a better atomised pattern instead of the standard stream with Bosch Version II, although some schools of thought say you get more power from liquid petrol entering the combustion chamber as there is more room for air?!?!?

Might take you up on the offer of your injectors though

What injectors are you looking at? if you look at all the online calculators, the 944 injectors are way too small for the HP they deliver

Ah ok, I guess I can wait another 3 weeks :D

That's an interesting theory...I'd have thought better atomisation is the way to go.

I'm getting these ones:

https://www.brisbanefuelinjection.com.au/products/raceworks-1300cc-length

They fit the stock fuel rail and injector harness...waayyy overkill for my current set up though, but should be future proof for 20ish psi on e85 later on down the track.

 

 

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10 hours ago, 944s2cab said:

According to this screenshot at WOT 6K rpm injector duty cycle of 96%

Question for people who know, Does this mean I need bigger injectors? (I think I do)

Would be an indication of increase in power if I've maxed out the stock injectors!!!!

Cab,

Does the 96% number ring true?

Since you haven't turboed it or increased the peak revs and only removed the restriction of the AFM surely the duty cycle could only change by a couple of percent over stock?

Could it be that the injector parameters (or fuel pressure) that are entered into the tune are incorrect?  It's hard to imagine that Porsche would install injectors with so little headroom.

Do you know the Bosch part number so you could do a check from first principles?

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3 hours ago, Peter M said:

True, but how do you know you actually need to run a pulse width of 19.3ms for WOT at 6000rpm?

Have you run it on a dyno and checked your actual AFR? 

It's all in the log, where I stopped the line (approx 10:14) corresponds to the figures on the left, 5963rpm, lambda .82 ( about AFR 12), pulse width 19.3

gSA962OnyOVtm_EoJNscsEpPPWvqtas3PKKHj90e

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Cab,

Was the engine at normal operating temperature at 10:14 and not subject to any warmup enrichment?

Was the engine subject to any transitional enrichment (ie the EFI equivalent to a carburettor's accelerator pump) at 10.14?

Sorry, I'm not confident with reading the data log correctly from the photo.

 

Do you know what Bosch injectors you are running now?  Do you know what your fuel line pressure is too?  

 

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2 hours ago, Peter M said:

Cab,

Was the engine at normal operating temperature at 10:14 and not subject to any warmup enrichment?

Was the engine subject to any transitional enrichment (ie the EFI equivalent to a carburettor's accelerator pump) at 10.14?

Sorry, I'm not confident with reading the data log correctly from the photo.

 

Do you know what Bosch injectors you are running now?  Do you know what your fuel line pressure is too?  

 

Yes, operational temp

I don't think any enrichment was going on

I presume stock 89/90 S2 injectors and stock Fuel rail pressure

If you take an online injector size calculator and punch in the details 210hp, 50 psi fuel pressure, 80% duty, most come back with a size around 320cc/min @3bar, 944S2 injectors are 277cc/min 

https://fuelinjectorclinic.com/flow-calculator

Although I'm not questioning Porsche designers or engineers, maybe the AFR was more conservatively set.

I'm only thinking of going to a 320cc/min version 3 Bosch injector

I suppose a dyno will reveal more

P.s My car is a UK model with NO O2 sensor from factory, a purely open loop system, one of the reason for going to VEMS was for a closed loop system

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The only other thing that could result in an artificially high duty cycle is if one or more of the injectors are old and partially blocked and this is effecting their actual flow rate.

But looking at your numbers show that a larger set is justified anyway.

Thanks for sharing your findings as you go as I know sfa on this topic but it is something I'm very interested in.

regards

Peter

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  • 2 weeks later...
On 05/01/2018 at 9:18 AM, Peter M said:

The only other thing that could result in an artificially high duty cycle is if one or more of the injectors are old and partially blocked and this is effecting their actual flow rate.

 

Now that got me worried (although my dad had them refurbed a few years ago) so I ordered these http://www.ebay.com.au/itm/OEM-Bosch-Fuel-Injector-0280155831-FOR-98-09-VOLVO-2-4-2-5-2-9-L-TURBO-set-of-5/201625035428?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649, they are

Doing my research they should fit but there's only one way to find out

Quick update, VEMS is progressing well, a few issues, oscillating when accelerating from low RPM and exhaust popping on decel between 2000 and 1000 RPM, I think due to injectors coming back on in time for idle, funny how it didn't do it with Motronic and I didn't notice it until the other day, I have also noticed the exhaust note is deeper, I have checked (quickly) for leaks, none that I can find, maybe a baffle has come loose, but there are no rattles,

The COP wiring was bugging me so I made up a solution from Bunnings shelving system

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89KZ_iI8yg78Q35RtT5Ds1Sz2okU_-Rft1bwgqQM

 

Going to soda blast the rocker covers and paint soon, I hear that Magnesium can be a little tricky, anyone have any stories

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