924Board.org

[kondzi]

Just an idea, as I'm thinking about the sensors I want for my 931 build.

Where would you fit one?
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Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded)

[Mike9311]

[Cedric]

Do you really need to run sequential?
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1980 924 Turbo
www.instagram.com/garagecedric/

[kondzi]

[morghen]

In general i have observed that it is best to keep things as simple as possible.
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https://www.the924.com

[kondzi]

[morghen]

Depends how much you want to push it.
The 924 turbo S2 only has crankshaft, CLT and MAP and the system works very well. But yeah the system can adapt and put out more power in some conditions if more information is know and taken into consideration.
But more sensors = more things that can fail.

Again, depending how simple you want to keep it.
IMO: pushing an engine so far that it needs all these sensors in order not to grenade itself is NOT keeping it simple.
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https://www.the924.com

[kondzi]

On the other hand you can implement failsafe strategy if any of the sensor fails... and a warning light ha ha

This is the syndrome of... "while I'm there"

I may never need those extra sensors, but while dyno-tuning it's nice to have them.
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Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded)

[924RACR]

On our old ITB racecar, we had a speed sensor installed on the output flange RHS of the gearbox. The sensor itself (AIM data speed sensor) was mounted on a bracket bolted to two of the bolts holding the diff in, and we stuck a magnet on one of the washers between bolts on the CV. If you had a slightly different type of sensor, you could presumably use the heads of the CV bolts themselves as a tone ring.

It wasn't perfect, as inside wheel spin throws it off of course, but it got the job done and did calculate gear (standard AIM data function).

Now we have GPS-based system on the car instead, and no longer need a trackside beacon, much nicer.

I have yet to add knock to my turbo, would like to someday.

Oil pressure - haven't added this to the racecar with logging, so just original stock analog sensors on both. My preference, also for fuel pressure, is the following 3-wire type... I'm using it to log both fuel and oil pressure on my prototype (GSXR motor), works much better than the old VDO style:
https://www.amazon.com/Pressure-Transducer-Sender-Sensor-Connector/dp/B08FR7G4QB

Main reason I haven't yet added it to the 924 racecar is because I've had good oil pressure to date, and if I start logging it I'll start to have something else to worry about!!
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[fblade]

[Beartooth]

I've always thought that on a vehicle with a distributor, being converted to EFI or coil pack ignition, it'd make the most sense to gut the distributor and adapt a CPS (or camshaft synchronizer, assuming you're running a crankshaft position sensor and depending on compatibility). I'm talking about the sort of CPS used on a number of 90s cars that combined older engine architecture with modern EFI; in place of a conventional distributor, some of them had a stub of a distributor just to drive a CPS. I haven't personally done it, but it seems like the most elegant solution. I'm with you on using sequential injection. It's not a huge difference, but it'd give you better idle and part-throttle, and I'm a sucker for any edge, even if it's nothing huge.
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1980 931 diamond in the rough

[924RACR]

Curious about the topic of part throttle response... when fighting with my CIS, I noticed that the tip-in response off idle (0% throttle) and transitional response in and out of that just was pretty rough in the 931, compared to a 924. I was surprised to find that, after MS/EFI conversion, that characteristic is unchanged, completely unaffected.

Driving in stop and go traffic, getting in and out of the throttle, it's just hard to be smooth enough with the pedal to avoid the occasional jerk as the throttle is cracked open off the stop.

I've come to suspect that this is just a fundamental characteristic of the driveability of that large single butterfly, and explains why other cars (like the NA) have a dual-choke throttle body or a progressive cam on the throttle. Modern cars just use electronics to smooth this out, also, I think.

It's an area where, unfortunately, our old cars just don't quite get as ideal as newer technology. Assuming my conclusion is correct... I guess I should ask one of my many friends in engine controls some day!

Anyone else notice the same?
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[kondzi]

I think it's not that much Air and Fuel related but Ignition related.
What I realised is that older cars (also the EFI ones) the responsiveness when going off throttle or on throttle when cruising is rough.
I was playing a LOT with ignition maps in the area of cruising (light throttle/part-throttle) to get as smooth transitions as possible and it was the only way to do it right. That's really pain in the ass by the way
The responsiveness to additional fuel or air is very low, it really takes a 1/2 of a second or more to realise something happened, but changing ignition advance is just a flash.

This is NOT related to 931 though, as I've never had a chance to drive my 931 with stock ignition (I had DITC and it was faulty when I bough the car - replaced with MegaSquirt and EDIS).
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Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded)

[Cedric]

Drive train jerk is also more than calibration(thoug modern cars also have lots of filtering and delay on tip in to make response slower and smoother), our cars have single mass flywheels, and the drive train is very stiffly suspended to the chassis compared to modern cars, which most of them are suspended in seriously computer simulated marshmallow engine mounts and subframes which also have marshmallow bushes. For my type of use I wouldnt have much use of a mushy modern drive train, would have needed to swap every bushing out anyway

I dont think anyone in here would easily notice the difference between batch and sequential injection, its mostly emission related.
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1980 924 Turbo
www.instagram.com/garagecedric/

[kondzi]

I do agree. There is no extra power in Sequential. Emissions and MPG, that’s it.

But I’m stubborn. I’d pair COP with Sequential - anyone fitted these? I have 2 types of Denso that fit the 964 an 911 Carrera 3.2 at hand, but it’s to tight fit for 931 IMHO.
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Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded)