924Board.org

[ideola]

OK, time for the official reveal. Here's what's in the works for proper engine management.

E85-prepped Fuel Safe Enduro ED115 (15 gallon) fuel cell (FIA certified and approved for SCCA and NASA venues). For details on the protective cage and installation, see my body work thread.




DTA Fast S60 Pro ECU and DIS, coil pack, custom aluminum fuel rail, FPR, injectors, crank trigger, etc.


Fuel Injectors (these happen to be Mitsubishi Evo 460cc high impedance injectors, but I will be replacing these with higher capacity injectors, specs TBD).


SARD adjustable FPR:


DIS crank trigger and sensor:


Coil pack:


Still needed to acquire:

• Fuel pump (leaning toward Bosch 044 unit, but evaluating other high end options)
• LC-1 Wideband O2 setup
• Miscellaneous wiring and sensors
• Fuel lines

_________________
erstwhile owner of just about every 924 variant ever made

[Rich H]

There are better options than LC-1 especially given the quality of the rest of the kit.
_________________
1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

[ideola]

[Rich H]

some of my friends run these and swear by them:

http://www.plxdevices.com/products/sm/afr/

I know of at least 2 guys who have had terminal LC-1 controller failures
_________________
1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

[simsport]

Not sure how the DTA system is setup but.I used one of those coils and had an intermittent misfire until we reduced the dwell time. We lost spark power and I went to M&W kit sourced from Steve Bassington and it is def better as a result.

Cheers
Simon
_________________
Blown is always best!

[Raceboy]

Misfire with higher dwell indicates two things: either you have crappy ignition leads or ECU doesn't support overlapping dwell feature and you are running out of dwell time at higher rpm's.

I would suggest VEMS WBo2+EGT kit as it's very compact (everything is in one standard 52mm gauge), has programmable lambda output and multiple display options via AIM data stream (you can display whatever data (rpm, boost, temps etc) your ECU is registering as long it supports AIM stream.
It's not the cheapest one (unit itself+LSU4+EGT sensor costs 310EUR) but definitely one of the best out there.
And you can choose display colour combination pretty much whatever you like.

EDIT: Here's link to it: http://shop.vems.hu/catalog/product_info.php?cPath=1&products_id=101&osCsid=84ad8176eecbe1a0d19d75e995ed90f2
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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

[RC]

It`s pointless running any longer dwell than it takes to fully saturate the coil. Increase dwell slowly while measuring coil current and STOP when optimum max current is achieved. Any longer only overloads the drivers, the coil winding and insulation, and will cause ringing or secondary discharges, ie. misfire.

Modern ECUs such as this DTA will reduce dwell if RPM raises above cycle time. A calculation will show it`s not a problem on a 4 cyl. Especially as this system appears to have 2 or possibly 4 coil drivers. A good coil should function well at only 1mS dwell anyway.

[bass gt]

I think the other problem Simon had was due to the fact he was running wasted spark ignition. So the coil was firing the same plug twice every cycle. If the dwell time was too high, then this would start to overheat the coil, and cause misfires. he has since gone to an M&W CDI i gave him and run it in full sequential mode.

Steve
_________________
Front Wheel Drive is the Devil's work.

[Raceboy]

Running wasted spark DOES NOT cause any misfire. It's not about the type of coil, but rather how ECU handles it.

I always tune to enough dwell not to give misfires and that's it. In most cases I don't run even factory recommended since it's not needed.

I've used both wasted spark and sequential on many engines up to 12 000 rpm and no problems whatsoever.

For example, recently I installed vems on Honda H22 and used exact 4cylinder coil-pack and that car revs up to 11 000 rpm, no misfires (vems has misfire detection also). Dwell is set to 3ms (coil is rated 4ms @ 13.5V).

And proper way dealing with rpm cycle vs dwell duration is overalpping dwell (next coil's dwell time is started before previous coil's dwell is stopped), not by reducing dwell time.
_________________
'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

[simsport]

Lots of knowledge as ever, great strength of this list is the number of people who have done this and that and are willing to share the learning.

In my case I was runing wasted spark as Steve has mentioned and using a coil pack commonly available for small saloons with Emerald M3D management. The dwell was 4ms (I confess that as it had never caused a problem we hadn't really noted it) and although we had always seen the odd misfire it was only when we upped the boost a little did it become a serious issue.

We then noted the higher dwell and reduced it to 2ms and the misfire went away. However at that time I decided that the system was too borderline for where the car was/was going to be hence the move to MOTEC and M&W.

What I can say with confidence is that at both of those steps the running improved. So I whilst I think the M3D system was great, I am sold on the MOTEC plus M&W system .

Cheers
Simon
_________________
Blown is always best!

[Lizard]

Dan,

I would recommend the 60# siemens injectors.

But can I ask what you paid and where you got your fuel cell. All the local guys with that style of cell want around $1050USD for it.
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3 928s,

[ideola]

[Lizard]

Thanks Dan, I think I may look them up and go from there.

Btw for the injectors, keep your eyes on ebay. I got 8 of them BRAND new for $200 + shipping :O most of the local places cost is $50/inj
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3 928s,

[ideola]

Custom fuel rail is nearly done, just needs anodizing:



Just a quick follow up on the injector issue. I had a conversation this week with my friend Scott Hoag (owner of Mustang Racing Technologies). He warned me against the Siemens injectors because MRT was experiencing as much as 20% variance across a set of 8 injectors. They lost two motors before they isolated the problem. He recommended that if I decide to stick with the Siemens injectors to make sure to find a supplier willing to provide flowed-and-matched sets.

In the meantime, Vaughan is working an angle to source comparably spec'd Bosch Motorsports injectors. Should know more in a few weeks.
_________________
erstwhile owner of just about every 924 variant ever made