275+ HP guys...
09-30-2002, 02:34 AM
#16
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my '86 turbo is completely stock with a lindsey racing boost enhancer. i can get 400+ miles (about half of that is highway) consistantly on about 14 gallons. plus many people have told me i've got a heavy foot 
09-30-2002, 02:41 AM
#17
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btw, all 951's have 21 gallon tanks? i usually fill 14 gallons and the auto-shut off thingy on the gas pump stops pumping gas, but my fuel gauge doesnt read full, it reads about 3/4 full. but i can also drive for about 100-150 miles before the little needle starts moving down
09-30-2002, 02:42 AM
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I have chips, a boost controller set to around 17 psi (probably right around 275 hp, give or take 10) and a 3 bar regulator (didn't affect fuel milage AFAIK), and if I do 60% highway and 40% city driving (about what I normally do), I usually get between 21 and 24 MPG, and I always boost it whenever applicable. I'll get 26 MPG if I do all highway driving usually averaging 70 or so. If I do only city driving while getting on it a lot, I'll usually get 18 or 19 MPG. Every once in a while, I'll get a freak tank of gas where I'll only average 14 or 15 MPG, but this is usually once every few months with no logical explaination. HTH,
09-30-2002, 06:13 AM
#20
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"You know, a couple of weeks ago I put 20 gallons into the gas tank of my '86 951. Also, I looked at the PET and noticed that the gas tank has the same part numbers for all years of 951's."
The PET program and the printed Parts & Technical Manual only shows replacement parts. Not original equipment that came on the car. For example, it doesn't show the part# for the forged con-rods that came only on the '86 951, but only the replacement cast rod that's available at the dealer now. Same thing with the gas tank. I usually put in 17-gallons to fill a tank, 18-gal. if I really pushed it to within 5-miles of running dry (I get 50-miles once fuel-light comes on).
If you look at the actual tank itself, the 21-gallon tank is like a saddle that sits over the tranny with both sides reaching down the same amount. The 18-gallon tank is only deeper on the right-hand side. The left side of the saddle only goes down as far as the top of the tranny.
My car must an odd-ball model that was up/down-graded at various times. It has the original 18-gallon tank, but has the accordion headers from the later cars. It also had the TurboS sway-bars as well, but I couldn't find any records of these upgrades (records go back to original owner).
"What does this KLR computer do? I know it's related to the turbo somehow, but how? ... I just didn't know how the KLR worked exactly."
Ok, this is Porsche's attempt at re-using as much inventory as possible. Since they already have the DME box in stock, they just added additional control functions for a Turbo on top with the KLR. So the KLR controls:
1. Boost - this is done through square-wave duty-cycle modulation of the cycling-valve. However, the duty-cycle curve is pre-programmed and there's no close-loop feedback to monitor boost. So the same signals will yield different boost-levels depending upon the turbo you have and the strength of the wastegate spring. On our EFI system, we're going to be retaining the stock CV for plug&play installation. Just manage it using closed-loop feedback to get consistent boost in all gears and RPM ranges.
2. Boost-gauge - there's a transducer on the KLR's board that takes in a pressure-reading from the intake-manifold. This is then converted into an analog signal to drive the boost-gauge on the dash.
3. Knock-detection - there's a knock-sensor on the head betwen the #2 & #3 cylinders. The KLR uses this as a microphone to listen in on the combustion. When it senses knock, it retards the timing. Yes, it's the KLR that retards the timing, but how can that be, if it's the DME that triggers the ignition coil? There's an interesting bucket-brigade going on here.
Ignition starts at the flywheel speed & reference sensors. This provides the DME with an RPM signal as well as a TDC trigger. These are used by the DME to drive the tach. The DME also sends a TDC trigger to the KLR. The KLR then passes this signal back to the DME, which then dumps the coil. If the KLR senses knock, it delays sending the trigger signal back to the DME, thus retarding the timing. The more knock it detects, the more it retards the timing. It's been said that the KLR also dials back boost-pressure as well, but the read-protect bit is turned on with the CPU on the KLR, so we can't read the code that it's running to determine what it does with the boost.
However, all the timing maps are on the DME. And the retard amount isn't based upon degrees off the existing timing. The maximum retard amount is based upon a crank-position itself. In this case, it's about 4-degrees after TDC. So if you're running in the partial-throttle/medium-load ignition map, you'll have about 30-40 degrees BTDC of ignition timing. So the maximum amoun of ignition retard you can have is 34-44 degrees.
Under full load, you'll be using the full-load/WOT ignition map and may have ignition timing in the range of 19-22 degrees BTDC. In this case, the maximum amount of retard is then 23-26 degrees total.
The KLR also outputs a knock-detected signal when it senses detonation. We'll be using this signal on our new multi-function gauge to drive knock/detonation LED.
4. Acceleration-enrichment - the 944NA DME can't sense a variable-voltage pot. on the 951's TPS. The 944NA only has two switches on the TPS; idle and full-throttle. The KLR's function is to measure the velocity of the TPS's operation (therefore your pedal-foot's actions). If it senses an opening of over 60-degrees under a certain amount of time, it will send a signal to the DME to provide additional fuel-enrichment over the current fuel-zones on the chip's map.
I was thinking about aftermarket control system, already have one in mind, with it I can customize fuel and spark maps for any driving condition...racing, traveling, around town, emission regulatory, etc. That way I wouldn't be restricted to one chip setting. The system I'm looking at can monitor/control any form of forced induction.
I'll cover this some other time somewhere else (with 3D maps & how to traverse them). But all these areas are distinct portions of the DME's 3D fuel/ignition-maps on the chip:
"any driving condition...
racing, <-- this is the full-load/WOT fuel/ignition map
traveling, <-- this is the middle of the partial-throttle fuel/ignition map
around town, <-- this is the acceleration-enrichment setting
emission regulatory, <-- this is the idle fuel/ignition map
An aftermarket standalone EFI system does not provide superior performance over a well-programmed stock DME/KLR system. That's because any optimal fuel & ignition setting can be incorporated into the chips. The only advantage an aftermarket EFI system has is instant adjustability in the event you make an upgrade and need to change fuel & ignition settings. But once you get that dialed-in on the dyno, you won't ever need to touch it again until your next upgrade. It's not like you're going to be sitting at a stop-light and then decide that you need to adjust your fuel & ignition to drag-race the guy in the next lane. If you have to make that adjustment, your system is certainly not tuned properly.
Most people upgrading to standalone EFI systems must have extensive experiencing in tuning the particular car. They must also have access to all of the fuel-maps and ignition-tables in the stock computers in order to have a starting-point. Or else your new standalone EFI system may be great and all due to its instant adjustability, but you had better know what the numbers are to plug in or else you'll end up with lower performance than the stock computers you're replacing...
The PET program and the printed Parts & Technical Manual only shows replacement parts. Not original equipment that came on the car. For example, it doesn't show the part# for the forged con-rods that came only on the '86 951, but only the replacement cast rod that's available at the dealer now. Same thing with the gas tank. I usually put in 17-gallons to fill a tank, 18-gal. if I really pushed it to within 5-miles of running dry (I get 50-miles once fuel-light comes on).
If you look at the actual tank itself, the 21-gallon tank is like a saddle that sits over the tranny with both sides reaching down the same amount. The 18-gallon tank is only deeper on the right-hand side. The left side of the saddle only goes down as far as the top of the tranny.
My car must an odd-ball model that was up/down-graded at various times. It has the original 18-gallon tank, but has the accordion headers from the later cars. It also had the TurboS sway-bars as well, but I couldn't find any records of these upgrades (records go back to original owner).
"What does this KLR computer do? I know it's related to the turbo somehow, but how? ... I just didn't know how the KLR worked exactly."
Ok, this is Porsche's attempt at re-using as much inventory as possible. Since they already have the DME box in stock, they just added additional control functions for a Turbo on top with the KLR. So the KLR controls:
1. Boost - this is done through square-wave duty-cycle modulation of the cycling-valve. However, the duty-cycle curve is pre-programmed and there's no close-loop feedback to monitor boost. So the same signals will yield different boost-levels depending upon the turbo you have and the strength of the wastegate spring. On our EFI system, we're going to be retaining the stock CV for plug&play installation. Just manage it using closed-loop feedback to get consistent boost in all gears and RPM ranges.
2. Boost-gauge - there's a transducer on the KLR's board that takes in a pressure-reading from the intake-manifold. This is then converted into an analog signal to drive the boost-gauge on the dash.
3. Knock-detection - there's a knock-sensor on the head betwen the #2 & #3 cylinders. The KLR uses this as a microphone to listen in on the combustion. When it senses knock, it retards the timing. Yes, it's the KLR that retards the timing, but how can that be, if it's the DME that triggers the ignition coil? There's an interesting bucket-brigade going on here.
Ignition starts at the flywheel speed & reference sensors. This provides the DME with an RPM signal as well as a TDC trigger. These are used by the DME to drive the tach. The DME also sends a TDC trigger to the KLR. The KLR then passes this signal back to the DME, which then dumps the coil. If the KLR senses knock, it delays sending the trigger signal back to the DME, thus retarding the timing. The more knock it detects, the more it retards the timing. It's been said that the KLR also dials back boost-pressure as well, but the read-protect bit is turned on with the CPU on the KLR, so we can't read the code that it's running to determine what it does with the boost.
However, all the timing maps are on the DME. And the retard amount isn't based upon degrees off the existing timing. The maximum retard amount is based upon a crank-position itself. In this case, it's about 4-degrees after TDC. So if you're running in the partial-throttle/medium-load ignition map, you'll have about 30-40 degrees BTDC of ignition timing. So the maximum amoun of ignition retard you can have is 34-44 degrees.
Under full load, you'll be using the full-load/WOT ignition map and may have ignition timing in the range of 19-22 degrees BTDC. In this case, the maximum amount of retard is then 23-26 degrees total.
The KLR also outputs a knock-detected signal when it senses detonation. We'll be using this signal on our new multi-function gauge to drive knock/detonation LED.
4. Acceleration-enrichment - the 944NA DME can't sense a variable-voltage pot. on the 951's TPS. The 944NA only has two switches on the TPS; idle and full-throttle. The KLR's function is to measure the velocity of the TPS's operation (therefore your pedal-foot's actions). If it senses an opening of over 60-degrees under a certain amount of time, it will send a signal to the DME to provide additional fuel-enrichment over the current fuel-zones on the chip's map.
I was thinking about aftermarket control system, already have one in mind, with it I can customize fuel and spark maps for any driving condition...racing, traveling, around town, emission regulatory, etc. That way I wouldn't be restricted to one chip setting. The system I'm looking at can monitor/control any form of forced induction.
I'll cover this some other time somewhere else (with 3D maps & how to traverse them). But all these areas are distinct portions of the DME's 3D fuel/ignition-maps on the chip:
"any driving condition...
racing, <-- this is the full-load/WOT fuel/ignition map
traveling, <-- this is the middle of the partial-throttle fuel/ignition map
around town, <-- this is the acceleration-enrichment setting
emission regulatory, <-- this is the idle fuel/ignition map
An aftermarket standalone EFI system does not provide superior performance over a well-programmed stock DME/KLR system. That's because any optimal fuel & ignition setting can be incorporated into the chips. The only advantage an aftermarket EFI system has is instant adjustability in the event you make an upgrade and need to change fuel & ignition settings. But once you get that dialed-in on the dyno, you won't ever need to touch it again until your next upgrade. It's not like you're going to be sitting at a stop-light and then decide that you need to adjust your fuel & ignition to drag-race the guy in the next lane. If you have to make that adjustment, your system is certainly not tuned properly.
Most people upgrading to standalone EFI systems must have extensive experiencing in tuning the particular car. They must also have access to all of the fuel-maps and ignition-tables in the stock computers in order to have a starting-point. Or else your new standalone EFI system may be great and all due to its instant adjustability, but you had better know what the numbers are to plug in or else you'll end up with lower performance than the stock computers you're replacing...
09-30-2002, 08:42 AM
#21
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Danno- why are you always so vague about stuff? Maybe next time someone asks a question, you'll actually make an effort to explain it a little? But seriously- very interesting stuff. I do have one question though- knock detection: KLR retards timing- what happens then? I mean, is your timing always going to be slower from then on, or does it re-set itself when you shut the car down, or do you have to re-adjust it w/the belt, etc, or what? Sorry if that's a stupid question- I've just always wondered since timing effects power. Anyway thanks for all the info- I can't wait to get some $ together to get my engine rebuilt and do some of this cool stuff...
As for mileage, I've heard other '86 951 owners say their tanks were smaller too. I always re-set my trip odo to keep up w/mileage- my Turbo S is stock, but... I probably run ~2/3 freeway and avg ~22mpg. When the light comes on, I have ~3.9gal left- I recently went almost 100 miles past the light- on cruise at ~80mph. I was starting to sweat, but I made it, and had used ~20.5gal. One time, ~6 months ago, after pulling a similar move, I stuffed (to the rim) just >21gal into it. And no, I don't normally do this. I've pretty much got it out of my system now- I just wanted to prove it really had a 21.1gal tank. I normally get gas when the light comes on. BTW- my gauge stops at ~3/4 too- I plan to clean the floater soon- been saying that for 3yrs
2yrs ago, I drove to St Louis- 505 miles one way. I made a total 495 miles before chickening out (the light never came on) and getting gas. I had made it (495 miles) in 5.5hrs- ~90mph avg- and yes, I played w/several cars along the way and REALLY opened up- it was dark (I left at 3:30AM)- I had the cruise set just under 90mph most of the way. I should have filled up when I got gas, to see exactly how much I'd used, but I didn't. If I assume the light was just about to come on, then I got 28.78mpg- I've never done that well since- I've gotten a hair >25, w/some stop & go- seems like the freeway makes a big dif w/this car- moreso than other cars I've had...
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
But seriously- very interesting stuff. I do have one question though- knock detection: KLR retards timing- what happens then? I mean, is your timing always going to be slower from then on, or does it re-set itself when you shut the car down, or do you have to re-adjust it w/the belt, etc, or what? Sorry if that's a stupid question- I've just always wondered since timing effects power. Anyway thanks for all the info- I can't wait to get some $ together to get my engine rebuilt and do some of this cool stuff...As for mileage, I've heard other '86 951 owners say their tanks were smaller too. I always re-set my trip odo to keep up w/mileage- my Turbo S is stock, but... I probably run ~2/3 freeway and avg ~22mpg. When the light comes on, I have ~3.9gal left- I recently went almost 100 miles past the light- on cruise at ~80mph. I was starting to sweat, but I made it, and had used ~20.5gal. One time, ~6 months ago, after pulling a similar move, I stuffed (to the rim) just >21gal into it. And no, I don't normally do this. I've pretty much got it out of my system now- I just wanted to prove it really had a 21.1gal tank. I normally get gas when the light comes on. BTW- my gauge stops at ~3/4 too- I plan to clean the floater soon- been saying that for 3yrs
2yrs ago, I drove to St Louis- 505 miles one way. I made a total 495 miles before chickening out (the light never came on) and getting gas. I had made it (495 miles) in 5.5hrs- ~90mph avg- and yes, I played w/several cars along the way and REALLY opened up- it was dark (I left at 3:30AM)- I had the cruise set just under 90mph most of the way. I should have filled up when I got gas, to see exactly how much I'd used, but I didn't. If I assume the light was just about to come on, then I got 28.78mpg- I've never done that well since- I've gotten a hair >25, w/some stop & go- seems like the freeway makes a big dif w/this car- moreso than other cars I've had...<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
09-30-2002, 01:43 PM
#22
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Danno, I see what you are saying about the DME/KLR relation compared to a aftermarket ECU. Guess I could save a little money buy buying the DME/KLR instead of aftermarket (could go to polishing or some sorts). 
Okay, I'm convinced about the computers and fuel mileage. Danno, you've got PM. Thanks to all you guys.
Okay, I'm convinced about the computers and fuel mileage. Danno, you've got PM. Thanks to all you guys.