924Board.org

[Arvidw]

@Flosho, 3 bar is indeed the most commonly used fuel pressure. The Bosch series 3 injectors can cope with a delta pressure up to 5bar. The flow from my injectors rises from 267cc/min to 355cc/min like Grenadiers already stated. Due to the higher pressure I've had to remeasure and recalibrate my injector settings in Megasquirt as depend on the fuel pressure.

I should have bought bigger injectors at the time, however when I bought these reconditioned items I was planning a NA setup... I don't like spending 200euro on new injectors but I have no other choice if duty cycle goes over 90%
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Porsche 924 2.0 Kompressor 136.1wHp @ 5650rpm / 201.9wNm @ 3900rpm (dyno @ dp-engineering.nl)

[Grenadiers]

Arvid, what CC injector size were you thinking of getting? Reason I ask, is that I'm running 2004 Neon SRT-4 injectors on MSII and EDIS, 59psi on FPR. Lots of fuel, but the VE table is doing quite well with them, little fuel smell in oil for example. I'm running the TMIC from Porsche, and 11 psi on boost. Not much soot in exhaust end of things (some leftover from previous oily engine). Car hauls ass, I'm quite pleased. Have a concern on engine temps though, not sure if HP related, too much fuel, etc.
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'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke

[Arvidw]

The SRT-4 injectors are around 550cc/min accoring to some fora. However as the SRT-4 head is a 16v head the injectors are most likely twin beam design. Te problem with these injectors in a 8V head is that the majority of the fuel spray doesn't hit the valve but sticks on the port walls:






In contrary my single beam injectors match the port shape significantly better:




A lot of people are running twinbeam injectors in a singleport head and normally it works just fine. It is however not the most optimal solution...
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Porsche 924 2.0 Kompressor 136.1wHp @ 5650rpm / 201.9wNm @ 3900rpm (dyno @ dp-engineering.nl)

[Raceboy]

I think "optimal" is not applicable to most of the solutions used on 924 or 931 engines, not stock and not modded.

I use Siemens Deka 630cc injectors which are four hole ones and these work like a charm.

Having not enough flow for given amount of air is much more problematic (=too lean AFR) than having a bit different spary pattern.
Also, SRT-4 injectors can be had for dime a dozen, that is quite "optimizing" aspect of them to me if I would have to seek an alternative.
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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

[Arvidw]

Haha Optimal is indeed a bit of a strange word when talking about a 8V engine developed in the 70's.

I hope I can get away with my 355cc/min injectors. According to some very basic injector sizing calculator I only need 4x270cc/min to make 170hp but I don't believe that. Last time on the dyno I was over 90% duty cycle with 136whp and 4x 355cc/min injectors (and a crappy fuel filter). I'll find out soon enough...


I made a flow guidance plate for the Eaton M62 supercharger last night. The old (and commonly used method) was just a plate and pipe but flow is really crappy with all these sharp transitions:



Now I made this: (hopefully it works as I spend quite some time making it)




And I finished the bypass pipe and flanges:

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Porsche 924 2.0 Kompressor 136.1wHp @ 5650rpm / 201.9wNm @ 3900rpm (dyno @ dp-engineering.nl)

[Arvidw]

Drove the 924 yesterday. The IC seems to be doing it's job perfectly as inlet temperatures dropped at least 40dg. The bypass valve however does not function perfectly yet, needs some tuning.


The cooling system proved to be insufficient for the 45minute long traffic jam I was in. Apparently one single 12" chinees ebay fan is not enough to cool the radiator. I had to use the heater in the car to cool down the engine. Not very comfortable Maby I should go for a double 944 fan as it is more compact than the 924 fan. (which doesn't fit anymore)


Unfortunately my fuel pump died on the way to see a friend:

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Porsche 924 2.0 Kompressor 136.1wHp @ 5650rpm / 201.9wNm @ 3900rpm (dyno @ dp-engineering.nl)

[Raceboy]

Ah, the good old dutch traffic jams which occur out of random sometimes When rain falls, when its too hot, when someone drives too slow then other won't pass etc... Been there with car many times and always catch at least one major jam. Almost like tulips and wooden shoes

Double fans are a necessity when 924 is boosted and IC is in front of the radiator. Also the radiator needs some shrouding so the air is not bypassing it on lower speeds.
On aftermarket fans usually shrouding is not necessary on fan side as they fit snugly onto radiator (you have to ensure that there is tight fit and no gaps between fan and radiator), otherwise fan is useless as it draws air from sides and not through radiator.

I would also suggest to turn the fans on earlier (with ECU) so the heat has less time to soak.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

[Arvidw]

Good old dutch traffic jams indeed, on a sunday afternoon Some guy crashed and skidded across 4 lanes so the police shut 4 of the 5 lanes to do an accident analysis. Even though our road's are of an exceptional quality and the driving tests in holland are very strict you still end up in traffic.

Thanks for the tips, if I understand you correctly I need some shrouding around the radiator as well? A bit like the left drawing a few posts ago? (Just to prevent the air from flowing around the radiator at lower speeds)

The 12" china fan I'm currently using is mounted flush to the radiator but only covers 1/3 of the surface area of the radiator. I'll get myself a 2fan 944 unit and switch the fans at 90dg coolant (87dg thermostat) or 35dg air inlet temperature.
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Porsche 924 2.0 Kompressor 136.1wHp @ 5650rpm / 201.9wNm @ 3900rpm (dyno @ dp-engineering.nl)

[Raceboy]

Yes, exactly like posted above, the 2nd drawing.

Dutch roads are amongst the very best I've ever driven, but you have a bunch of cars and people (15+ million) stuffed to an area smaller than Estonia (45 000 km2) We have only 1.3 million people and 800 000 vehicles so less crowded but inferior roads.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

[Arvidw]

I just found out why my china fan was blowing so little air, I connected it the wrong way round Now it is running in the right direction it is less shitty than before but I'm still going to mount a 944 fan and radiator.


Did a 1500-6000rpm run in 3d gear with the new intercooled setup to measure IAT's. The bright colored lines in the figure below are the old (no IC) setup, the gray-ish lines is the new setup:


Went from 53.5dg rise in approximately 13 seconds to 5.7dg, which is very nice. Boost dropped quite a bit so I'm going to check for leaks (pressurize intake with air compressor)
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Porsche 924 2.0 Kompressor 136.1wHp @ 5650rpm / 201.9wNm @ 3900rpm (dyno @ dp-engineering.nl)

[Arvidw]

I converted my vacuum opperated bypass valve to a throttle driven vacuum valve. The vaccuum actuation didn't work as expected so it was ditched after a couple of runs. Now I made a pull-pull linkage setup driven from the original throttle body. A short video can be found on youtube using the following link:

http://youtu.be/YUHF2evONzY

It works very well, in contrary to the turbosmart BOV or the vacuum opperated bypass valve this does give a very predictable and constant throttle response / reaction. As the bypass valve is nearly completely open during cruising the supercharger noise is very low and I think don't need to switch it off at all.




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Porsche 924 2.0 Kompressor 136.1wHp @ 5650rpm / 201.9wNm @ 3900rpm (dyno @ dp-engineering.nl)

[morghen]

Setup looks great...but..are you still runing that copper soldered rail? i think you can get a ford mondeo 1.8 benzin rail and it will work.
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Supercharger and EFI kits
https://www.the924.com

[Arvidw]

Thanks, I used o have a mondeo 1.8 fuel rail but ruined it when I tried to weld brackets to it using a stick welder. The welds where porous so it developped a leak

Replacing the rail is number 3 on my to do list, first I'll have to do some maintenance on the body (get rid of surface rust)
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Porsche 924 2.0 Kompressor 136.1wHp @ 5650rpm / 201.9wNm @ 3900rpm (dyno @ dp-engineering.nl)