Herb,

Try the Weltmeister chip. I have the Authority chip also however I didn't spend a lot of time comparing the two. I think as long as its a reprogrammed chip, the differences between chips are kind of like splitting hairs, maybe 1 or 2 hp difference - DME calibrations make more of a difference after that. Stock chips for the Carreras were programmed at a time of a fuel crisis in the United States, with conservative timing and fuel maps assuming the car may have run on regular unleaded. What I found was strange in two '84s I had, the California car was a bit slower than my non-California car by a half sec 0-60. I found the chip in my California car had a different number on it from the other car. Replacing the chips on both with Weltmeisters gave them identical performance. This may explain discreptancies in the gains claimed by chip manufacturers. Most chip tuners are/were based in California, and if gains were measured off a underpowered California car, the same chip placed in a New York car may not show as much gain.

The Weltmeister chip is actually a chip programmed by Dinan Engineering years ago, and Weltmeister is a Performance Products brand. You might want to try and test if removing the airbox cover or drilling it along with enriching the mixture through the DME calibration switch helps - after all you are comparing the MAF with the barn door sensor. I had a conversation a few years ago with a manufacturer of a cone style K&N filter/adapter for the barn door sensor. They told me in their dyno tests, most of the gains from the MAF came from the elimination stock airbox. They found that replacing the stock airbox with a cone filter(and internal velocity stack adapter) plus a chip yielded the same gains as the MAF system.

Also since you are running a modified exhaust with the stock chip, your car is probably running a little lean, causing your car to run a little slow. Remember at full throttle, the O2 sensor is ignored and fuel is injected a premapped rate for a stock motor. You may have gained 10 hp from a performance cat premuffler and muffler, but lost 5 due to lean running conditions, netting you only 5 hp gain.

 

Rich-
My Dansk exhaust is single-in and single-out. I also have the Dansk cat by-pass. The muffler alone, I think, does have a nicer sound. And with the cat by-pass, it is quite a bit louder and throatier. (When I ordered, I was told the SSIs were not that much of a HP gain for the money, I've since heard otherwise from a number of folks.) I'll live with what I have for now. With your SSI/Dansk set up, I assume you have removed the cat? Are you 'smoking' more since then. Without the cat, I have noticed that my car smokes a bit when coming to a stop (high vac condition)....it got 75K mi on it and I'm guessing its tired valve guides. But it never showed such smoke with the cat...I assume the cat is pretty darn efficient at converting any burnt oil as well. My consumption is not too high but the smoke is annoying. BTW, I'm up in Rochester NY. Soon the weather will change, and 'talk' is all I'll have. But the weather is good this week and I'm drivin'! Thx for the info.

 

Steve-
Good thought on my running a bit lean with the new exhaust. I've got to try the adjusted DME settings...
I am running with a modified air-box. I neatly drilled a grid of about 24 or so 1/2 inch holes across the lid. The sound is much nicer, and it likely helps HPs with the perf muffler. I didnt find any noticeable HP change when I had done the airbox by itself some months ago. Hopefully it will also help with a chip as well. Thx for your comments on the Weltmeister chip...the price is attractive compared to some others as well($299 at PP) Regarding the Weltmeister chip, do you know if the rev limiter is raised? I'd actually prefer not to raise the limiter and save my conn rods, but I do want improved sub-redline driveability. I understand that the Rennsport chips dont raise the limit but they're a bit pricier...but may be worth it in the end. I'd love to hear from someone that has one in a Carrera.

 

Herb,

I don't know about the other chips, but my Autothority chip raises the engine cut-off by 400 rpms.

Regards, Bruce
'84 911

 

Hi Herb E, and others.
I have the Autothority MAF system on my 88.
I had it installed in August of this year.
I like it. My guess is that it feels about
like 20 more horse power (engine HP) from
stock. A 20 HP increase is about a 10% gain for the stock 3.2. That turns out to be 234
(engine) H.P. Sorry that I have no dynos to
back up my estimate. The only credibility
I can give to my statement is that I have owned six porsches and have a feel of various porsche engines, 914,944,964,993,& 928.
My MAF 3.2 slots halfway in between a stock 3.2 and the stock 964 3.6.

One customization that I did was to have
a custom rev limit programmed into my chip
when I ordered the MAF from Autothority,
programmed to rev out at 6800 RPMs. On *my*
tachometer it registers 6750...this is nice.

Herb, I suggest that if want to go with a chip only, consider a company that will
program the chip with a 6800 rev limiter
for you. Autorthority can. Also
I think Steve Weiner can do a custom
rev limit for you. Check with him. Steve (Weiner Motorsport) kindly told me the info about 6800 being tops for a stock 3.2. So consider his chip too.

About chips only...before I went with the MAF
system, I installed the Autothority chip
(their standard chip). It did increase
power, but I never found the rev limit...
honestly. I don't know if Autothority
let slip a chip w/o a rev limiter or what,
but I tried three times to find the rev
limiter of that chip, each time passing 7000 rpms. I was nearly crappin my pants waiting for the rev to kick in and it didn't!
So, rather than blowing up my engine, I returned the chip, and in exchange bought the
MAF kit with the custom 6800 rev limit.

Comparing the Authority MAF system to the Autothority chip alone. The MAF has more power than the chip alone. Comparing the two...1000 RPMSs to 2800 RPMS had no difference. 2800 to 4000 felt
quite similar in gains. But the MAF
from 4000 to 6800 was noticeably stronger
and smoother than the chip alone. The MAF
really opened up above 4000, quite more
than with just a chip.

A couple concluding notes on the MAF.
When the engine is cold, the idle isn't quite as smooth as stock, but once warmed up, the idle sits pretty at about 800 rpms. I think this is a small trade off to having more usable power.

Best of luck, Vaughan

 

Vaughan,

Your original Autothority chip could have been defective , because mine cuts out the fuel pump between 6750 and 6800 rpms. I have their standard chip (no MAF system) that is used on the 911 Carrera's.

Bruce