928 Supercharger Crankshaft pulley
03-10-2003, 02:28 PM
#1
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928 Supercharger Crankshaft pulley
I have successfully supercharged the 16v Porsche 928. This track car and its dyno pages can be seen at <a href="http://www.928trackcars.com/fausett." target="_blank">www.928trackcars.com/fausett.</a> The CIS adapted to the boost without modification, and the early cars with the 9 to 1 compression ratios are setup well for a blower. I had to make all my own parts - there were (are) no kits for the early 16v cars. What I am wondering is: I have my 6061 Billet Aluminum crankshaft pulley off right now while I am doing other work on the motor. I could - if anybody was interested - get some copies made of it. Trying to find out if anybody would be interested... there are photos of the crank pulley at the website above, it has all the sheaves for Power Steering, Alternator, AND A/C belts. Any questions or interest - just email me at carl928@charter.net
03-10-2003, 03:32 PM
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Carl,
What do you think the cost would be? I recently had one made by having a 6 rib pulley welded to the air conditioner pulley. Ihe 6 rib replaces the PS v pulley. I am sure the Aluminum would be superior is why I inquire.
Where did you get the idler pulley to make your belt tennsioner?
Thanks
Andy K
What do you think the cost would be? I recently had one made by having a 6 rib pulley welded to the air conditioner pulley. Ihe 6 rib replaces the PS v pulley. I am sure the Aluminum would be superior is why I inquire.
Where did you get the idler pulley to make your belt tennsioner?
Thanks
Andy K
03-10-2003, 04:18 PM
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Last edited by PorKen; 09-23-2003 at 02:02 PM.
03-10-2003, 11:33 PM
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Thanks Porken for the picture! That's my motor and that's the pulley I am talking about. I think I can get them made and sold for about $560 ea. They are thick and strong - I ran mine up to 12 psi of boost no problem including racing at Road America,
03-11-2003, 01:31 AM
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The brackets will vary with the centrifugal blower you use, and the location. I used a Powerdyne BD-11a and mounted it where my broken AC compressor was. Other use a Vortech or other brand, and mount it where the belt-driven fan is. Your choice. If you want a kit where verything is picked out for you - try FAST in Texas. If you want a pulley and an Intercooler and you are going to make the rest yourself, I offer this option. I will be making and selling the intake elbow that replaces the airbox for charged air hookup too.
03-11-2003, 05:16 AM
#7
Burning Brakes
Will the pulley work for all models? My supercharger is still to my left, just waiting to be used, but I have to get the pulley figured out, and a way to do the brackets. Plumbing is a sinch.
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03-11-2003, 09:22 PM
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quick carl,
i also have a 16v 928 (1984) thats currently under construction with a supercharger being installed with the help of FAST.With my set up the supercharger is by vortech and takes the place of the stock fan with a electric fan being installed right to the radiator.What boost did you start off with?
i also have a 16v 928 (1984) thats currently under construction with a supercharger being installed with the help of FAST.With my set up the supercharger is by vortech and takes the place of the stock fan with a electric fan being installed right to the radiator.What boost did you start off with?
03-12-2003, 01:23 AM
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Lots of questions! Let me give them a try...
Yes, the crankshaft pulley I am making will work on all 16v models. I hear the 32v 928's have their power steering a little further inboard and the pulley shives might not line up right. But on a 16v motor, she's just right. My pulley (picture above) is cut from a single 6061 T6 Alloy aluminum billet. One piece. Very strong. Ran it at Road America and Blackhawk Farms Raceways in 2002, hit 130+ MPH many times and 155 MPH on the DynoJet Dyno, runs true, no fatigue, no problems. It will support all belts including AC, Power steering, and Alternator. I built in a 6-rib design for the blower pulley. Yes, I mounted my supercharger where my AC compressor was, but you do not have to do that. My AC system on my '78 was gone, I just pulled it to save weight, and who wants AC on a track car in Wisconsin anyway? But, if I was more southerly, I'd mount the blower where the clutch fan is like F-A-S-T does. I see a lot of blowers mounted there and it seems to work well. I just didn't like hanging that much weight so high center-of-gravity wise on my track car. I started with 9 psi of boost - ran up to 11 psi later in the season - while I was between intercooler designs and had none. Big Mistake! Detonation blew the piston lands out of 3 pistons. And you know what? I was not any faster - with the 11 psi pulleys on the blower, I had to shift at 5000 RPM to keep from overspooling the blower. My ET's with the 9 psi pulleys shifting at 6200 RPM were better, and did not harm my motor. You live and learn. Photo of one of the hatched pistons is on this webpage at the bottom: www928trackcars.com/fausett
Tomorrow I will put up some pictures of this crank pulley on eBay on my eBay store "928 Motorsports" I am having the machinists make me a coupla more for whoever wants them. Need to get $620 ea for them. I am also making copies of my intake elbow - replaces the air box and allows me to hook a 3" tube from the blower to the intake plenum. Don't know what that will come in at price-wise yet. So- I'll be selling the crank pulley, the intercooler, and the intake elbow. You just need mounting brackets. Can't make them for you unless I tell you what brand and model centrifugal blower to buy and where to put it. I used a Powerdyne, but you might like a Vortech or ?? Too many variables. But truthfully - the brackets were the easiest part to make. I did have an engineer help me compute the side load on the blower under full boost and full load. He calculated that the belt drag/pull would max out at about 80 linear pounds of force. He advised me to build my blower brackets 20% stronger than that, and we did at least that. Put a micrometer on them and then pulled with a spring hoist to 120 pounds of force and the mounting brackets did not flex a bit. No flexing is allowable because alluminum will work harden and crack under repeated flexing. Any other questions?
Yes, the crankshaft pulley I am making will work on all 16v models. I hear the 32v 928's have their power steering a little further inboard and the pulley shives might not line up right. But on a 16v motor, she's just right. My pulley (picture above) is cut from a single 6061 T6 Alloy aluminum billet. One piece. Very strong. Ran it at Road America and Blackhawk Farms Raceways in 2002, hit 130+ MPH many times and 155 MPH on the DynoJet Dyno, runs true, no fatigue, no problems. It will support all belts including AC, Power steering, and Alternator. I built in a 6-rib design for the blower pulley. Yes, I mounted my supercharger where my AC compressor was, but you do not have to do that. My AC system on my '78 was gone, I just pulled it to save weight, and who wants AC on a track car in Wisconsin anyway? But, if I was more southerly, I'd mount the blower where the clutch fan is like F-A-S-T does. I see a lot of blowers mounted there and it seems to work well. I just didn't like hanging that much weight so high center-of-gravity wise on my track car. I started with 9 psi of boost - ran up to 11 psi later in the season - while I was between intercooler designs and had none. Big Mistake! Detonation blew the piston lands out of 3 pistons. And you know what? I was not any faster - with the 11 psi pulleys on the blower, I had to shift at 5000 RPM to keep from overspooling the blower. My ET's with the 9 psi pulleys shifting at 6200 RPM were better, and did not harm my motor. You live and learn. Photo of one of the hatched pistons is on this webpage at the bottom: www928trackcars.com/fausett
Tomorrow I will put up some pictures of this crank pulley on eBay on my eBay store "928 Motorsports" I am having the machinists make me a coupla more for whoever wants them. Need to get $620 ea for them. I am also making copies of my intake elbow - replaces the air box and allows me to hook a 3" tube from the blower to the intake plenum. Don't know what that will come in at price-wise yet. So- I'll be selling the crank pulley, the intercooler, and the intake elbow. You just need mounting brackets. Can't make them for you unless I tell you what brand and model centrifugal blower to buy and where to put it. I used a Powerdyne, but you might like a Vortech or ?? Too many variables. But truthfully - the brackets were the easiest part to make. I did have an engineer help me compute the side load on the blower under full boost and full load. He calculated that the belt drag/pull would max out at about 80 linear pounds of force. He advised me to build my blower brackets 20% stronger than that, and we did at least that. Put a micrometer on them and then pulled with a spring hoist to 120 pounds of force and the mounting brackets did not flex a bit. No flexing is allowable because alluminum will work harden and crack under repeated flexing. Any other questions?
03-12-2003, 01:35 PM
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Carl,
When you popped the ring land, how well did the motor run? Did you run a leak down with the broken lands?
I am deep into my 1981 Bastard which has always run like a champ, but a bleed down showed 90% on piston 1. Granted my engine was stone (i.e. 45 degrees) cold and had not been run for two months! Dumb move on my part, I should have warmed it up before checking it out.
Let me know. No intercooler with 11 psi and 9:1 compression....now that takes guts! You were way outside the guidelines! I have a friend that runs a 9:1 Mustang motor without an intercooler at 9 psi. It moves like a monster.
When you popped the ring land, how well did the motor run? Did you run a leak down with the broken lands?
I am deep into my 1981 Bastard which has always run like a champ, but a bleed down showed 90% on piston 1. Granted my engine was stone (i.e. 45 degrees) cold and had not been run for two months! Dumb move on my part, I should have warmed it up before checking it out.
Let me know. No intercooler with 11 psi and 9:1 compression....now that takes guts! You were way outside the guidelines! I have a friend that runs a 9:1 Mustang motor without an intercooler at 9 psi. It moves like a monster.
03-12-2003, 01:39 PM
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One other note....Callaway made one single turbo car which had no intercooler and used water injection. It detonated and crushed the ring lands as well...Marc at Devek did the teardown on the motor. With that level of compression anything over 6 psi should probably have a charge cooler. Mine is medium sized, 3" thick, 6" tall and about 18" long....sits right out front in the air stream for good cooling.
I always go bra-less!
I always go bra-less!
03-12-2003, 03:24 PM
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Yes - it was dumb to run without an intercooler. I had paid my race entry fee already and my welder had promised my intercooler back in time, but didn't make it. Whattya gonna do? The season points championship was on the line and I decide to go ahead. The engine ran very well with the broken ring land. The only clue was the amount of oil I pumped on deceleration - blue smoke a plenty. I was filling a 1 quart catch tank in 2 laps of a 2 mile road course. I did not do a leak-down test before I tore it down - we pretty well knew what we'd done.