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DME capabilities?

I have a 87 N/A that I do track days and autocross with. I absolutely love the way the car handles. My question is this: what sort of mods is the stock dme capable of handling (without tuning)? Web cam, head porting, larger injectors, higher compression, limited amounts of boost?

Thanks.
Old 02-09-2018, 04:44 AM
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with a totally stock DME...

yes:
porting, cam

no:
larger injectors

"maybe":
boost, compression

the DME using the AFM flapper is quite forgiving for airflow mods.
the stock injectors should be good into the ~180hp range however you would need to tweak the DME fuel quality switch and/or the AFM clock spring to make sure your air-fuel ratio was good at high rpm. however without a DME tuner theres no way to tell the DME what size your non-stock injectors are so fueling would be off, everywhere.

the reason is that past about 4500rpm at WOT the AFM door is stuck wide open and isn't measuring airflow anymore - so the DME is sort of guessing at the fuel based on its programming (2.5L engine with stock cam at 5000rpm takes in X air so needs Y fuel, etc)

compression the DME can deal with but there's only a very limited amount of spark timing adjustability built in to the fuel quality switch, i think it's something like -2.7 degrees which might be sufficient for a 1/2 point of compression (stock 9.5 up to 10:1 maybe?). same goes for boost, you would really want to run the highest octane fuel available if you intend to boost.

realistically you're about 50 steps ahead if you contact Lindsey Racing and get their MAF conversion with DME tuner kit.

Last edited by v2rocket_aka944; 02-09-2018 at 06:33 AM..
Old 02-09-2018, 06:29 AM
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V2Rocket (Spencer) - Knows these cars, and is providing some good advice.

If you aren't trying to stay in a certain class....and the Track days & Autocross is more for fun .... I would do the MAF Conversion and add 4 degrees advanced timing (with an offset camshaft key). These can be done in an afternoon and yield some good (safe) results.

Depending on your suspension and tires, that is really where your money needs to go to keep this car up to the pace of the other cars on track. Koni Shocks, Turbo or 968 Sways, upgraded or new rubber suspension bushings.

You can really go deep into the rabbit hole chasing hp on an 8V NA, and the money would be better spent on an S2, 968, or Turbo if Hp in a 944 Chassis is the goal.
Old 02-09-2018, 07:43 AM
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Thanks for the info guys. I totally agree with not doing too much. I am just trying to arm myself with a little information on what I can easily and safely do to get "what is worth getting" when I decide to refresh the motor.

I am rebuilding the control arms and replacing all bushings this weekend and a 4' cam key is on the way.
Old 02-09-2018, 10:08 AM
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no other way to say it, sorry pelican, but...

driving the first time with the cam advanced 4 degrees will give you a strong erection.
Old 02-09-2018, 11:03 AM
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Quote:
Originally Posted by v2rocket_aka944 View Post
no other way to say it, sorry pelican, but...

driving the first time with the cam advanced 4 degrees will give you a strong erection.
HAHAHA.......

Thanks for making my Friday!
Old 02-09-2018, 12:15 PM
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Look on the Rogue Tuning site for software and instructions on how to reprogram the fuel and ignition maps. One good mod is advancing ignition 3-5 degrees for use with +91 octane gas. You can program the FQS for different size injectors or E85.
Old 02-18-2018, 11:27 AM
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Thanks Danno. I have looked at the rogue software but have not downloaded it. Maybe its's because I am an older guy, but it doesn't appear to be super user friendly. If you don't have any ecu tuning experience, is it something anyone with a little mechanical ability can do?

Also hit a snag. Pulled my timing cover and realized I set the cam gear one tooth retarded last spring because I didn't use a flywheel lock (no wonder I don't like the performance...). My plan was to pull the gear and install the offset cam key. The 12 point bolt will not budge. I hit it with PB Blaster, tried to wake the bolt up, and it still wont move. I am now in danger of rounding off the bolt. I read the instructions on Clark's garage and it seems fairly straightforward. The bolt isn't a left hand thread is it? At this point I'm wondering if I should just set the cam gear correctly and not change the key.
Old 02-19-2018, 02:36 AM
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Are you using a high quality 12 point tooL Make sure you tapp it into the bolt head with a hammer to fully seat it. This does two things, breaks free corrosion and seats the tool to reduce chances of rounding. Replacement bolts come with the cam seal kit on Pelican.
Old 02-19-2018, 05:32 AM
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I am a noob with this tuning stuff, but if your are off one tooth on the belt, I think it will affect cam timing, but ignition timing is controlled by the crank sensors, not the distributor. For ignition timing you have to change the DME software. I think there is a manual switch on the stock DME to slightly adjust ignition timing.

I personally highly recommend the Rouge MAF kit due to the precision of the MAF sensor and the 3-D fuel maps. You also get some timing advance and need to run 89 octane minimum.
Old 02-19-2018, 05:40 AM
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Quote:
Originally Posted by tocheck View Post
Thanks Danno. I have looked at the rogue software but have not downloaded it. Maybe its's because I am an older guy, but it doesn't appear to be super user friendly. If you don't have any ecu tuning experience, is it something anyone with a little mechanical ability can do?
These were are finely-tuned close-to-the-limit of technology for their times. Modern hot-rodding is all about software. I was able to get +50bhp out of my 951 simply from re-programming chip settings.

This is the final step in ALL mods; to program new fuel & ignition-maps to take advantage of your mechanical mods. There's very little bolt-on mods that will give you anything worthwhile. Best gains are from the inside out starting with high-comp pistons, custom-cams, larger valves, head porting, etc. Even with those mods, without optimally tuning for new configuration, you'll only get 20-30% of possible gains. For example, age-old trick is to advance ignition-timing for high-octane fuel. So you dump in some VP 110-octane fuel, then how do you advance ignition? The FQS switch on DME only allows you to retard ignition, but not advance it. To advance, you need to re-program the chip maps.

Take your time, learn the software, read the manual, consult various on-line forums for the software (there's a tonne, as same software is used by millions and millions of hot-rodders).
Old 02-20-2018, 12:52 PM
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there is a good amount of power left in US spec 944 to be found by adding timing suitable for 91 or 93 octane (stock 82-87 944 only need 87).

however before looking at cams or pistons, valves or headwork, the #1 thing you should really do is ditch the ancient AFM for a MAF or MAP conversion.

Lindsey Racing carries the Rogue MAF kits now - it is truly transformative to how the car drives. worth every penny, and it's plug and play, you don't have to mess with tuning at all until you start changing other stuff, like the cam etc.
Old 02-21-2018, 06:03 AM
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I bought a better quality 12 point tool and was able to get the bolt out. It was really tight and almost rounded. Took my time using steady pressure and blocked the wrench holding the cam gear so I could use both hands on the wrench. Threw my cheap 12 point bit in the trash. Waiting on a new bolt and then I can't wait to drive it with the cam set correctly with the 4' offset.

Everywhere I turn, the Rogue MAF comes up. Guess I will start saving my "change" so I can do the mod this summer.
Old 02-21-2018, 07:58 AM
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Also, I am a dumb a**. The car is a a 88 not an 87. So I have the higher compression engine.
Old 02-21-2018, 08:08 AM
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I wonder what upper-limit for compression on NA engine is? Europeans got 10.6:1 pistons with extra 20bhp. With E85, we should be able to run 12:1.

New Ducati Panigale V4 uses 14.1:1 pistons on pump gas... hhmmm....
Old 02-21-2018, 08:15 AM
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Danno,
2.7L 944 was 10.9:1 for 91 octane, and it's huge bore should've made it even more sensitive to spark timing than a little old 2.5. I don't believe it had KR capability either?

To an extreme if you changed the resonant length of the intake manifold and maybe a hotter camshaft I would think a 944 could live happily into the 11 or 12:1 range on pump gas.
Remember, RPM and cylinder pressure make the difference for a given static CR...
Old 02-21-2018, 08:27 AM
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Quote:
Originally Posted by v2rocket_aka944 View Post
no other way to say it, sorry pelican, but...

driving the first time with the cam advanced 4 degrees will give you a strong erection.
Things dried out enough that i was able to test drive the car tonight with the timing set correctly and the 4' key installed. All I can say is... Erection achieved!

It is like a different car. It really pulls pretty good now. Can't wait to get it on track and hopefully pass a little easier when I get a point by.
Old 02-23-2018, 02:43 PM
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Old 02-23-2018, 06:47 PM
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