DME 'remapping' question:
 

From what I've read, the DME in the (catalyst) 3.2 Carrera's from '87 on had been remapped and improved upon, thereby resulting in a hp rating of 217 over the 207 from '84-'86. Does that then imply that a stock DME chip can be taken from an '87 and then placed in an earlier Carrera in order to benefit from the hp increase???

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Adam Nitti
ajnitti@mindspring.com
www.adamnitti.com
'85 911 Carrera Coupe
PCA member, Peachstate region

I understood it as being a conservative claim in pre '87 carrera's. No real difference. Or maybe my mechanic just wanted me to feel better.

Joseph
'86 T-look

Unfortunately, the Carrera chips are not interchangeable between early and late 3.2; early ones are soldered on 24 pin and others are socket type while the 87 and some late production 86 chips have 28 pins that plug into a socket.

If you are looking for is a cost effective way to increase your low end and mid torque performance, I would look into setting your mixture with an externally adjustable mixture control device as you would commonly find in a general aviation aircraft so you could tune your engine to Pemax while you drive.

I made an adjustable mixture control valve that I can set while I drive and I can tell you that it has to be the most cost effective way to make your 3.2 feel as quick as a 3.6, lower your engine temperature about 10 degrees, allow you to take off in second gear comfortably, cruise in 5th gear at 30mph without it bucking, and give you an extra 50 miles to a tankfull of gas at the same time.

Is there anything else out there that can do any of this for $100 or less and has been approved by the FAA for general aviation use?

Joe Gaecia
86 Carrera
Redwood PCA since 1976

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Joe -- are you going to share how you did this?

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Bill Krause
'79 911SC Euro

Joe,

Can you provide some more detail on what you put together? Do you have to tweak it constantly or do you set-and-forget? Any dyno numbers?

Here is a product by Huntley that sounds similar -

http://www.huntleyracing.com/engineproductswhole.htm

It's $550. Maybe you have a more cost effective solution.

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Chuck Moreland - '86 Cab, '77 Targa, Family Truckster

If you were at the Parts Heaven swapmeet on Sunday, I had it on dislay on booth #98.

What I had on display was a kit that included everthing that you needed to install in you car; the modified gate valve, 8' speedometer cable with an adjustment knob on one end that you could buy for $100.

If I weren't such a lugnut I would have figured out how to get a picture on this BB so everyone could see what I have.

I know about what Huntley has but I think it is unnecessarily complicated and expensive for what it is. On a Cessna, all you need turn is one knob; so I made it just as simple.

My younger brother, the MD (the gifted one), is comming up the end of the month with his digital camera and hopefully show me how to figure out this dang computer picture thing.


Joe

PS: I don't know how reliable my G-Tech meter is, but it's telling me I have 220hp at the rear wheels based on 2960lbs with a full tank of gas.


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Is this just for a 3.2 with DME?
What's the procedure for operating it?

I've only tried it out on my Carrera and can only assume that CIS could benefit as well, espcially in the area of altitude compensation.

I'm not sure what you mean by operating proceedure, but what could be easier than turning one knob for optimum performance?

I think Huntley Racing requires you to dial in three separate adjustments...far too complicated to be useful for the average driver.

Joe

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I understand the 87-89 Carreras use a different DME because they incorporate a knock sensor, and have higher compression ratio. This knock sensor allows more advanced timing without detonation. If detonation (knock) occurs the computer retards the ignition. I think I read this in Bruce Anderson's book.

This is not available on the '84-86 Carreras.
Hence, a little more advnaced ignition, and higher compression ratio gives you a little more HP.

Joe, I am interested to hear more on your "Dial".

TIA

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Nick Hromyak
'85 Carrera 7 & 9 Fuchs
Havin' Fun in Sacramento

Joe ,this sounds very interesting.I am wondering what type of feedback you have from this setup.I mean do you just turn in or out depending on how the car reacts to the adjustment or do you have some type of feedback loop display to tell you where you are set?? I am also wondering if you must change the setting constantly to compensate for your running speed to feel an effect??
Sounds like a GREAT idia.

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Mully 911

If all you do is turn a knob for optimum performance, why don't you just leave it in one place? How do you know you are at optimum performance? What if I want optimum economy, how do I set the knob for that?

How can this device work on a DME and on a CIS system?

I'm a private pilot, so I know about setting mixture in small airplanes. Keeping a close eye on EGT is critical, but 911's don't typically have those.

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Bill Krause
'79 911SC Euro

Bill,

Aircraft engines spend most of there lives at 60 to 80 percent of peak hp, I think that is why the EGT is critical compared to a car whose engine spends most of its life cruising at maybe 10 percent of peak hp.

Optimum performance can be found by turning the knob until you find the sweet spot which will make itself very obvious from where you are sitting. At that point, there is no further need for adjustment unless you are planning a trip over Donner Pass and if you're a pilot you'll know what to do.

The reason DME and CIS are able to take advantage of this device is because they both rely on air flow meters that have adjustments for mixture, where as mass air flow meters are not adjustable.

Joe

I have an 86 Targa with a chip, it runs well,
I've always thought it had decent power. This weekend I picked up a 87 Cab to bring back to Northern Cal to sell for a friend.
I drove it from SoCal to Monterey and really noticed a difference. The car is really quick. It has 135K miles and runs like stink. Maybe it's the increased comp. ratio, whatever, it really is nice.
(Maybe I should keep the Cab and sell the Targa...hmmm)

Bruce Herrmann
73 911s
86 Targa
87 Cab (for sale)

Doubt if it's the compression ratio since all US 3.2's came with 9.5:1.

It could be that the mixture on the 87 was set better than your 86.

I had a similar experience with an 87 that I tested. The difference I noticed, however, was just the opposite. The 87 felt slow and lethargic compared to my 86 which felt like it could run circles around it. And this was before I figured out how to set my mixture for performance.

All I can say is that a slight mixture change can make a big difference in the way it affects performance.

Joe

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Good to know, think I'll check the mixture on the 86. I'm also wondering if the
87's G50 ratios could be a bit different
causing a slightly different feel, a bit
better acceleration perhaps....?
Thanks Joe


Bruce Herrmann