85 86 Autothority chip, exhaust combo

12magnum · 01-29-2007, 05:42 AM

I have a 1986 928s with the 32V engine. A few months ago I installed a Autothority Chip set. It was a great improvement. My question is: Has anyone used this chip in combination with the x-pipe from 928 specialists or 928 motorsports on a 85 or 86 model?. I am wondering how these parts work together. will I need to do any other tuning? Any dyno results?

I am leaning towards the 928 specialist kit with the removable cats. I live in Kentucky and no emission check is required. This kit is $649. the comparable kit from 928 motorsports is $983. If i get the kit with no cats from 928 motorsports with no cats in mild steel, it is cheaper.

928 motorsports claims 27 hp. 928 specialists claims 24 hp.

I probably would have already installed a RMB, but my car is the early 86 model so it is not offered.

Incognito · 01-30-2007, 03:19 PM

With an X pipe already installed you won't get much if any additional HP from a RMB and if you can only pick one or the other then the X pipe gives you more than a RMB...so get the X it will add to the improvement and don't worry about the RMB unless you want to get that sound.

Just keep your injectors clean, your fuel filters clean and fuel pumps working (both of them if you have two) etc. to make sure your fuel is being delivered as best it can and check your plugs once in a while to see if you are running lean.

I don't think any other tuning is warranted until you introduce more air into the mix from what I've learned, then again I don't know what your chips are tuned for, one size fits all and all that, for example, I got some Autothority chips for my S4 along with an X and RMB and the chips didn't really help but they say that's because the newer models factory chips are already tuned pretty aggressively so yours will benefit from the chips more than mine did.

12magnum · 02-01-2007, 04:41 AM

incognito, thanks for the reply. I am mainly interested in the performance increase from adding the x-pipe. removing the cats also saves weight, and from what I understand adds a little growl. my 928 needs some more growl. it's too quiet.

could a gt or gts intake be put on a 85 or 86 model? with all these guys putting superchargers an their later model cars there might be some extra intake parts laying around. intake ports on the head are slightly larger on the later models so some adapters might need to be made. throttle linkage might need to be changed. would my MAF, throttle body and air box work?

12magnum · 02-01-2007, 08:39 PM

thanks for the info about putting the s4 intake on a earlier model. Sounds like a complete wate of time and money.

some modifications are a waste of money. The autothority chip for my car is supposeed to add 22 hp. I thought the chip was a waste of money and I would not have purchased it, but i found it used for cheap. It really added some punch to my car. In some cars a chip is worthless though.

It's good to know how much power a modification will add. It's even better to know how much it will change you 0-60 or 1/4 mile time. i would like to be under 6 seconds flat 0-60. I think it's possible with the chip and exhaust mod. any actual results would be appreciated. beyond those mods I think you would need to shed some weight to go much quicker without breaking the back. I don't want to start stripping my perfect interior though.

I don't think a S4 is much quicker than my car if at all. It might have a higher top speed. I wouldn't consider selling mine to get the s4. My car is spotless, completely sorted and has only 68000 miles- it 's a keeper. The 86 928s is only rated at 288 hp. but i belive this is underrated. Some euro model 928's are rated at 300HP. my car can and has whipped a 300 hp euro model. my car hangs right with other porsches when we go on drives with the local porsche club including the 928gts. the autothority chip in my car is supposed to add 22HP. that means my car is now 310hp. I belive the 86 928s weighs less than the s4 too. I sould go get my car on a scale to get the actual weight.

DanielDudley · 02-16-2007, 01:52 PM

12Magnum, that is a great car ! The only one I'm sorry I let slip away was an 86.5. Mine had a chip and a RMB. I can't say how the RMB affected performance, but it sure sounded stout !

I would think if you added an X, a trip to the dyno would be in order, before and after. They would also hook up a sniffer to your exhaust, so you would be able to detect a lean running condtion at WOT. I believe that there are ways to optimise this, in my case a new MAF solved the problem.

I don't think a RMB would ever cause lean running on it's own BTW, or really give you more than a great sound.

Danglerb · 02-17-2007, 01:33 AM

I've heard nothing but good things from people using an X and a chip in the 85/86, but once you have an X and high flow or no cats the RMB seems to only make a difference in sound, not power.

I don't recall any discussion of it, but I wonder what it would take to run factory or JDS chips in a pre 87, new brain or what. Being able to hook up to a shark tuner seems like a great advantage if its practical to do.

DanielDudley · 02-17-2007, 01:39 PM

87 + has a different brain, wiring, knock sensors, limp home ,etc. , so yes a major undertaking. Someone please correct me if I am wrong.

Fabio421 · 02-17-2007, 02:06 PM

That will be a non issue soon as John Speake is currently working on a version of the Sharktuner that will interface with the 85 and 86 cars. So burning a custom chip for the early 32v cars will be possible.

rhjames · rhjames's Garage

I'll dive into this one just for fun......

Arclight has valid point that it is sometimes easier to start big, and work forward (32V as opposed to 16V).

However, there are drawbacks to each direction.

I had considered transplanting a 32V into my current ride (it houses a 4.5L 229hp Euro and I know of a donor---cheap), but when you start talking about transplanting engine, wiring harnesses (including the main harness), fuse panel, and computers (2 of them), it's a no brainer to realize this is way too much trouble. As Arclight said, easier to sell the 16V car and upgrade to a 32v ride.

If you are stuck on building a 16V (like me--for several reasons), you do have several options, all of which depend on how much $$$ and time you want to invest.

I finally got steered in a correct direction as to the differences between the 16V engines as a group.

I was led to believe that all Euro 16V engines would have the same upper end parts. NOT SO!!!

Only the M28/11 (or 12) engine has the 300hp heads, cams, intakes and throttle body. The M28/09 (my engine) used the US spec heads, cams, intakes, throttle body.

So here's the deal. The consensus of opinions on building a high HP 16V involves the following:

short block----early 32V (86-87) 5.0L-maintain at least 10:1 compression ratio

Heads, intake, throttle body----M28/11 (or 12) 300 hp

Cams----M28/11 (or12) 300hp sticks or aftermarket. There is some discussion that the cam towers limit the size of the lobes, so there is a limit as to how big you can go with a custom grind. Webcam in LA can help.

injection----either K-Jet cis or L-jet, depending upon what your car already has in it. With the K-Jet, you don't have to deal with computers and electronic fuel injection, and it will handle upwards of 500 hp. If you use K-Jet, you will need to fab up some mounting tabs for the cis unit. After that, just crank up the fuel pressure.

These are just the basics, so one needs to decide how much and how deep you want to pursue that illusive 50 to 100 HP that Arclight has written about.

There are other items that will give you more HP for little (compared to superchargers, turbos, strokers and such....) money:

1. improved exhaust---I'm exhausted from writing about this one in my other posts. Headers (MSDS), x-pipe (3 inch), Flowmaster mufflers (3 inch inlet/3 inch outlet) and twin 3 inch pipes to the rear. Yes, this does add (some) weight, but if you believe the advertised #s, there's maybe 75 real HP by just doing this one mod. Some have said there is no gain with RMB. To them I say, "Show me the numbers." Anytime you free up the exhaust flow, you gain HP. Much of my exhaust mod is custom work, not the stuff you buy off the shelf and hope will fit. About $1500.00 to do this right.

2. removal of mechanical fan/ air pump, replace with electric fan---- there's 25-35 HP depending who you believe (you're removing 2 pulleys of crankshaft drag)--several companies have kits to do this, at about $250.00.

3. Fuel delivery mods----you can't make power without adequate fuel delivery at all RPMs. I have seen no discussions on this subject (?) and there are electric pumps (Barry Grant, for example) that will flow enough to power a 1500hp Pro Stocker. Match that with a #10 line to and from the engine, with Grant pressure regulators and filters, you can go fast for sure. Remember, it isn't just about pressure, volume has it's place in this item as well.

4. Ignition----MSD mods have been talked about....Hotter sparks are just a necessity for bigger HP engines.

5. Weight----For every 100 pounds you lose/remove, you cut 1/10 off of your 1/4 mile times. (My 1980 Euro is nearly 400 pounds lighter than the late GTS models. Think about it....) I don't advocate stripping your interior, but lightweight racing seats are lighter (maybe another 100 pounds?) than your electric powered cushy ones, and those heavy factory wheels/tires add up, too. My 19 inch Carrera 997 wheels/Toyo T1R tires actually weigh less than the 16 inch set up I had before.

Five easy mods, and I haven't even started on internal mods to the engine. We're talking about 100 hp net gain for under $2 grand, and coupled with the weight reduction, you're looking at close to the same performance figures as a GTS without spending $30-$70K.

Short of all of this, strap on a 200HP shot of Nitrous and be done with this......

Let's see, 5 mods plus Nitrous equals 300 hp (minimum) gain for less than $2500. Wow, that's $3500 less than ANY supercharger or turbo set up, $17,000 less than a stroker, and a minimum of $20,000 less than a GTS. AND, 100 more HP than the fore mentioned power adders.

Arclight is right on with his analysis. It is easier to hotrod a big block than to start off small block and play catch up. Similarly, Wally Plumley is also dead-on (Buy the newest car you can afford).

The only argument to this is that Porsche's are not about going fast in a straight line, they are about taking corners at high speed, for long distances.

If you want a ride to jack with the local tuner crowd, well....that's another thing.

regards---rhjames

All general statements are false. (Think about it.)

125 mph blast down the front straightaway, chasing a late Corvette, at Texas World Speedway. While he did pull away from me on the straights, I was all over him in the corners.......

rhjames · rhjames's Garage

Geez that was rediculously long, but I was bored.

My apologies for those who still don't get it, or those who are new to the differences between old and new 928's.

rhjames

12magnum · 02-18-2007, 05:02 PM

who knows anything about this shark tuner under development for 85-86 models? I might be interested in one. Do i need it though? I already have the autothority chip for my car.

I think i might need just the x-pipe for my car and the the new escort 9500 radar detector

Danglerb · 02-18-2007, 05:24 PM

www.jdsporsche.com is the sharktuner guy.

Correct on the Euro stuff, only the S model is hot, the M28 11/12 is the 300 hp, and M28 21/22 is the later 310 HP using LH brain instead of K and with a slightly improved cam, sometimes called a S2.

The hybrid design uses a 5.0L block from a 85/86 model, and requires cutting new 16v style valve reliefs in the pistons.

Its a hot motor, its what I want for my car, what many 16v guys want for their car, so parts are in short supply and go for a premium over normal 16v parts. I haven't found all the parts to commit to one direction or another yet, so I am still digging into options like porting US heads, or using a custom ground cam instead of the Euro S or S2 cam. Most of the track guys, which are most of the hybrid motor guys, have used the K injection system which is CIS and requires an 80-83 Euro S intake.

If there is current interest enough maybe we should start a hybrid motor thread and start loading links and other references to it?

MGW-Fla · 02-20-2007, 12:13 PM

I have an '85 32v with the AutoAuthority Chips and 928 Specialists X pipe without the cats. You'll love it! Not only the additional git up & go but the sound most definately is an enhanced grunt! Well worth the $$ in my book.

They say for an '85-86, the best bang for the buck is to replace the chips & an X pipe with cat delete. Anything else to enhance the HP/torque is not too cost effective for the gain.

12magnum · 02-20-2007, 05:42 PM

Thanks for the post MGW-Fla. Sounds like you have the same car as me. I have the 86 automatic with AA chip. I plan on adding the same x-pipe with cat delete that you have done. Any idea on your 0-60 time or 1/4 mile time? did you just disconnect the Air pump or did you remove it? Once I have installed the x-pipe, that is as far as I'm going.

MGW-Fla · 02-21-2007, 06:15 AM

I've never dyno'd it or been timed in the 1/4, etc. Most say that just removing 20+ yr old cats can make a difference, but the Xpipe definately does. It certainly adds to the chips & the sound change is gonna put the biggest smile on your face! I'm sure you've looked at the dyno charts that DR has on his 928 Spec. web site for our 32v cars. Hard to argue with those stats. I had my mechanic take out the air pump when I had him do the TB/WP last year & put on the lawnmower Vbelt to turn the fan.

12magnum · 02-21-2007, 08:23 AM

some where I saw exactly which belt is needed to run only the fan after removing the air pump. I see 928 motorsports has a kit to remove the belt driven fan and install a 3000cfm electric fan including all hardware and temp switches for $249

MGW-Fla · 02-21-2007, 09:54 AM

I've had multiple people tell me there is an electric fan for less than $100, but I don't remember specifics. The situation with going with an electric fan can be relays and or altenator output, due to increased electric consumption, but again, I'm no expert on the specifics, just what I've been told.

The belt is for a lawnmower, most use around a 21"+/- size. Gates makes a belt that you can buy from NAPA for about $6. I bought either a 20" & 21" or a 21" & 22". I took them both to my mechanic & said, which ever one fits the best in your opinion, that works for me. I took the other one back. Sorry I can't remember what exact size worked for mine, but its been a year now & all appears well.

Danglerb · 02-21-2007, 02:58 PM

I made a electric fan thread on R list. The top fans are OEM units, and the ones I hear the most good stuff about are;

Lincoln Mark VIII,
Taurus 3.8 V6,
Volvo (not sure of model, maybe 3000?)
Dodge Ram Charger dual fans.

As soon as the body shop and stereo place are done with my 83 the electric fan will be replacing the dying clutch fan. I have a junkyard Mark VIII fan, which is a freaking monster in person 18" and 4300 CFM rated at 35 amps, and to tame that power draw I have PWM controller from Delta Controls, www.dccontrol.com that does a soft power ramp up, and runs the fan continuously with the speed matched to the temperature load.

Other good fans, but IMHO not as good, are Spal and BeCool, but I have heard of too many problems with Spal's PWM controller, and there relay stuff is as good as any relay stuff.

Carl has a nice packaged setup for $249 I think, thats been reported to work well, just wasn't exactly what I wanted. I don't want to use relays on the 83 due to the high turn on current some fans have, and I don't want to mount the fan directly to the radiator fins. OTOH I doubt my install will look as nice. I'll post some picts when I am done.