Those Interested in Turbocharging your L-Jetronic 928 read here...
02-24-2004, 09:38 AM
#19
Three Wheelin'
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The motor is coming from Garland, TX and I was told it was a US spec. Won't matter, cause it is just a place holder anyway. I will know for sure in a few day's time. Hey, if it is a Euro, this might get interesting! The hope is for a stock M28.15
300 crank HP is not any issue, but you would probably want more than that if you were going to drop some money on it. I would feel comfortable with 8 lbs on the regular internals, that is for a street car that won't get the tar beaten out of it on a track.
Gotta run, fixing up some prototypes today at my "paying" job!
300 crank HP is not any issue, but you would probably want more than that if you were going to drop some money on it. I would feel comfortable with 8 lbs on the regular internals, that is for a street car that won't get the tar beaten out of it on a track.
Gotta run, fixing up some prototypes today at my "paying" job!
02-24-2004, 09:46 AM
#20
Nordschleife Master
I'm still curious where your going to place the turbo.
I promise not to pry into the details, like how your going to run the plumbing, or how exactly that MAF conversion works, or even if your going to use it. However, I am very curious as to where that turbo is going to go. The only place I can think of that will allow you to keep the intake looking mostly stock is under the engine, but that would be a pain to work on.
Anyways, just curious.
I promise not to pry into the details, like how your going to run the plumbing, or how exactly that MAF conversion works, or even if your going to use it. However, I am very curious as to where that turbo is going to go. The only place I can think of that will allow you to keep the intake looking mostly stock is under the engine, but that would be a pain to work on.
Anyways, just curious.
02-24-2004, 10:07 AM
#21
Administrator - "Tyson"
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You keep saying anything over X boost and you need to rebuild the engine internals. Are you referring to the lower end (rod bearings, crankshaft, rods) or the pistons/rings/cylinders?
02-24-2004, 12:22 PM
#22
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ViribusUnits,
Mine is located on the right side, bottom of the motor. you are right in the fact that is is a pain to work on. lots of plumbing both on top of and on the botom of the motor. Stock airbox is retained and so is the AFM.
SilverSFR
Mine is located on the right side, bottom of the motor. you are right in the fact that is is a pain to work on. lots of plumbing both on top of and on the botom of the motor. Stock airbox is retained and so is the AFM.
SilverSFR
Last edited by SilverSFR; 02-24-2004 at 01:54 PM.
02-24-2004, 12:49 PM
#23
Nordschleife Master
AFM...
L-jet cars came with an AFM stock.
AFM = Air Flow Meter measure the quantity of air by volume.
Later cars came with the MAF.
MAF = Mass Air Flow, measure the quantity of air by mass.
L-jet cars came with an AFM stock.
AFM = Air Flow Meter measure the quantity of air by volume.
Later cars came with the MAF.
MAF = Mass Air Flow, measure the quantity of air by mass.
02-24-2004, 02:15 PM
#24
Three Wheelin'
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Hacker, yes the cast pistons are the issue with running mega boost. I know of several Callaway 944s that ran around for 15+ years on cast machined pistons with 12+ lbs of boost, and then one of the drivers installed a bra with no air inlet to the IC and decided to run it out on a hot day... the charge air got too hot and it detonated badly and broke a couple of pistons. That car got the 951 set and all is fine. A forged piston might have done the same thing, who really knows? The root cause was the bra. There are factory forced induction cars with cast pistons, the Supercharged Ford Thunderbird is an example. I have a friend who was running a Mustang Cobra with 9:1 compression 10 lbs of boost, no intercooler and he blew up the bottom end, ring lands to be precise. He needed a charge cooler for sure. I'm not entertaining building this car without a charge cooler, since I view it is a necessary piece of the system, as have Tim and Carl on their high end buildups. Any new forced induction car you purchase today will most likely have charge cooling. The cooler will easily shed 80+ F off of the intake charge.
Other than the block treatment and pistons+pins, my internals are all stock. A better set of rods would have been nice, but I didn't have the patience or desire to spend another couple of grand and as I always said I am building a street car, not a track car. If you want to build a track or race motor, you are into a different league. I am talking about a reliable street motor you can run into the boost as much as you please. We are not talking about a car you are going to go out and run flat out for 10 miles at top speed, though that would be cool. To do that you need to drop some coin on the bottom end, but who ever does that on the street? Besides, to make this car run out of 5th gear won't take full boost, or at least not as much as I will run on the demo motor.
With just 5-6 lbs of boost, the 928 will run effortlessly and offer awesome mid range torque to boot. Remember, this setup will have the advantage of giving lots of boost from about 3200 on out. Talk to SFR, he has a rare 6 lb of boost 928 with no charge cooler and an old 1970s designed turbo that is probably in the very low 70s for efficiency. Even at that, that car is probably making at least what a stock 32v S4 car makes and probably has more torque. Some of the newer Garrett stuff is 78% efficient, but the one I have my eye on is at 76% peak and can be matched up with 4 A/Rs on the turbine side. We will probably go with the biggest (1.06) A/R to start and see where it builds boost. We can then step down the housing for better low speed response. SFRs car has lasted 15+ years without charge cooling on 6 lbs of boost. I'm sure that setup can deliver a lot more air, but a charge cooler will be needed to push the envelope.
Why do you worry about where it will be located to work on? Assuming all goes well, it should run without the need to be touched for 100,000+ miles. That is longer than any set of syncros has lasted in an early 928 gearbox to put things into perspective. Look how long turbos go on diesel rigs and diesel equipment. My cousin told me he changed one out last week with 14,000+ hours on it. At 2 hours of use a day, that is 7000 days, or 19+ years. And those turbos run higher duty cycles than a gasoline turbo usually does. That is a long time and the myth that turbos always fail is just that, a myth. The turbo is always blamed for other problems, but seldom is it the problem. Changing out a turbo would not be any worse than doing a timing belt or water pump change on the 928. To answer your question directly, right now I have not yet decided where it will be, but I know it can be done and done properly. Having the "Texan" engine out of its habitat will be superb! I'd be willing to bet SFRs car nor any of the Callaway 928s had their engines removed for conversion, which is even more impressive given the space constraints. This method will allow for more conceptual work before a final layout is selected.
Other than the block treatment and pistons+pins, my internals are all stock. A better set of rods would have been nice, but I didn't have the patience or desire to spend another couple of grand and as I always said I am building a street car, not a track car. If you want to build a track or race motor, you are into a different league. I am talking about a reliable street motor you can run into the boost as much as you please. We are not talking about a car you are going to go out and run flat out for 10 miles at top speed, though that would be cool. To do that you need to drop some coin on the bottom end, but who ever does that on the street? Besides, to make this car run out of 5th gear won't take full boost, or at least not as much as I will run on the demo motor.
With just 5-6 lbs of boost, the 928 will run effortlessly and offer awesome mid range torque to boot. Remember, this setup will have the advantage of giving lots of boost from about 3200 on out. Talk to SFR, he has a rare 6 lb of boost 928 with no charge cooler and an old 1970s designed turbo that is probably in the very low 70s for efficiency. Even at that, that car is probably making at least what a stock 32v S4 car makes and probably has more torque. Some of the newer Garrett stuff is 78% efficient, but the one I have my eye on is at 76% peak and can be matched up with 4 A/Rs on the turbine side. We will probably go with the biggest (1.06) A/R to start and see where it builds boost. We can then step down the housing for better low speed response. SFRs car has lasted 15+ years without charge cooling on 6 lbs of boost. I'm sure that setup can deliver a lot more air, but a charge cooler will be needed to push the envelope.
Why do you worry about where it will be located to work on? Assuming all goes well, it should run without the need to be touched for 100,000+ miles. That is longer than any set of syncros has lasted in an early 928 gearbox to put things into perspective. Look how long turbos go on diesel rigs and diesel equipment. My cousin told me he changed one out last week with 14,000+ hours on it. At 2 hours of use a day, that is 7000 days, or 19+ years. And those turbos run higher duty cycles than a gasoline turbo usually does. That is a long time and the myth that turbos always fail is just that, a myth. The turbo is always blamed for other problems, but seldom is it the problem. Changing out a turbo would not be any worse than doing a timing belt or water pump change on the 928. To answer your question directly, right now I have not yet decided where it will be, but I know it can be done and done properly. Having the "Texan" engine out of its habitat will be superb! I'd be willing to bet SFRs car nor any of the Callaway 928s had their engines removed for conversion, which is even more impressive given the space constraints. This method will allow for more conceptual work before a final layout is selected.
02-24-2004, 02:21 PM
#25
Nordschleife Master
Cause it would be a pain the the butt to have to pull the engine to install the turbo.
Plus, I thought it would be cool to have a gliming turbo compresser houseing onthe top of the engine. Course, I also think the spider is cool, so thats good too.
Plus, I thought it would be cool to have a gliming turbo compresser houseing onthe top of the engine. Course, I also think the spider is cool, so thats good too.
02-24-2004, 02:38 PM
#26
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Originally posted by John..
RE on the boost levels...yes it is about the CR. I feel confident these engines can handle 6-9 lbs if properly set up. The car will run very responsively on just 5 lbs of boost and that will easily get you to 928 S4 levels of power and performance with more in the torque department. With 8-9 lbs you are looking at a 350 crankshaft HP car with no head or cam work whatsoever.
The goal isn't to post a super-man dyno number, but to create a smooth streetable 928 with some very desirable performance that is also reliable. If you want to build a crazy HP 928 then you should really be looking to prepare the bottom end to take the pounding. I believe this induction system will support quite a bit of power when it is all said and done.
RE on the boost levels...yes it is about the CR. I feel confident these engines can handle 6-9 lbs if properly set up. The car will run very responsively on just 5 lbs of boost and that will easily get you to 928 S4 levels of power and performance with more in the torque department. With 8-9 lbs you are looking at a 350 crankshaft HP car with no head or cam work whatsoever.
The goal isn't to post a super-man dyno number, but to create a smooth streetable 928 with some very desirable performance that is also reliable. If you want to build a crazy HP 928 then you should really be looking to prepare the bottom end to take the pounding. I believe this induction system will support quite a bit of power when it is all said and done.
I have the greatest admiration for your project, so don't get me wrong, but why go through all the time and expense for such a modest boost in power level?
A plain old euro, or an S4 with a few mods would be pushing that level of horsepower.
It doesn't seem terribly attractive until you start talking 400+ crank HP.
02-24-2004, 03:11 PM
#28
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Originally posted by John..
...and then one of the drivers installed a bra with no air inlet to the IC and decided to run it out on a hot day... the charge air got too hot and it detonated badly and broke a couple of pistons.
...and then one of the drivers installed a bra with no air inlet to the IC and decided to run it out on a hot day... the charge air got too hot and it detonated badly and broke a couple of pistons.
If there is a Darwin award for car deaths, this would be a winner.Thanks for the explanation. When you said "bottom end", I was curious because from my (limited) experience the crank/bearings/rod combo on these cars seam very strong. At least the S4's are (I've ridden in Tim and Lag's car a few times) that is where my question was coming from.
02-24-2004, 07:14 PM
#29
Three Wheelin'
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400 crank HP will be easy, I'm already past that with 10 lbs. Lots of guys out there with the older cars who want to keep them. With any luck, one of these setups will find its way onto a 928 S4 at a later date... 375 or 400 HP, not that much difference in the grand scheme of things. Remember I am talking power levels of the smallest and least powerful of the 928s. The 4.7 and 5.0 liter cars would make more, with the same or even less boost. The extra displacement of the 5.0 liter would be a significant benefit. As I said, I don't know where it will end up, but the screw will get turned down on it for sure. The point I was making is that just 5 lbs of boost will get you beyond stock 928 S4 levels of power.
Trust me, I don't want to pull another engine either, so that will be one of the limiting factors on where it ends up.
Trust me, I don't want to pull another engine either, so that will be one of the limiting factors on where it ends up.
