How can this be? No compression in all 8 cyls ?
05-03-2008, 10:15 AM
#166
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Well, thanks for reminding all of us that we are human. Stuff happens.
That car looks like its running 100+ just sitting still.
Set your mind to it, it will be fixed in no time. And worth it.
That car looks like its running 100+ just sitting still.
Set your mind to it, it will be fixed in no time. And worth it.
05-03-2008, 11:43 AM
#167
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Coupla thoughts. Several years ago, I sold an '89 engine to a poor soul in Florida because his fresh rebuild had a little sand (from sand blasting) left in the intake which destroyed the engine in short order.
Motor-Vac might be an option. It will clean the system, but the process works on a running engine. It might be possible to hook up the system and crank in the hope that it starts and then does it's magic? Compared with pulling and replacing gaskets and such, towing to a shop and using this system might make sense in terms of time and money.
I have a clean 130k mile '79 short block with bearings and rings that have about 15k miles on them. Nothing wrong with it other than 130k worth of wear and as I recall, compression was just a bit below new specs - but that might be a good thing for a charged engine. It needs a home if interested.
Motor-Vac might be an option. It will clean the system, but the process works on a running engine. It might be possible to hook up the system and crank in the hope that it starts and then does it's magic? Compared with pulling and replacing gaskets and such, towing to a shop and using this system might make sense in terms of time and money.
I have a clean 130k mile '79 short block with bearings and rings that have about 15k miles on them. Nothing wrong with it other than 130k worth of wear and as I recall, compression was just a bit below new specs - but that might be a good thing for a charged engine. It needs a home if interested.
05-03-2008, 07:04 PM
#168
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Coupla thoughts. Several years ago, I sold an '89 engine to a poor soul in Florida because his fresh rebuild had a little sand (from sand blasting) left in the intake which destroyed the engine in short order.
Motor-Vac might be an option. It will clean the system, but the process works on a running engine. It might be possible to hook up the system and crank in the hope that it starts and then does it's magic? Compared with pulling and replacing gaskets and such, towing to a shop and using this system might make sense in terms of time and money.
I have a clean 130k mile '79 short block with bearings and rings that have about 15k miles on them. Nothing wrong with it other than 130k worth of wear and as I recall, compression was just a bit below new specs - but that might be a good thing for a charged engine. It needs a home if interested.
Motor-Vac might be an option. It will clean the system, but the process works on a running engine. It might be possible to hook up the system and crank in the hope that it starts and then does it's magic? Compared with pulling and replacing gaskets and such, towing to a shop and using this system might make sense in terms of time and money.
I have a clean 130k mile '79 short block with bearings and rings that have about 15k miles on them. Nothing wrong with it other than 130k worth of wear and as I recall, compression was just a bit below new specs - but that might be a good thing for a charged engine. It needs a home if interested.
05-09-2008, 11:33 AM
#169
Race Car
An '86 motor, some miles though:
https://rennlist.com/forums/showpost...13&postcount=1
Was a recent thread on someones 5L track motor too, quite a project.
https://rennlist.com/forums/showpost...13&postcount=1
Was a recent thread on someones 5L track motor too, quite a project.
05-09-2008, 11:59 AM
#170
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I think Mark is referring to AF ratio, and it appears you may be referring to CR.I agree 100% with your post & it's very informative, but telling someone with a boosted motor to lean it out to cool down the charge is misleading and that is what Mark said that I was addressing.
I guess for me (and I know other people due to message's I have recieved) it worries me to see posts like this coming from Mark who is about to tune a very expensive race motor this forum paid for.
05-09-2008, 12:48 PM
#171
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Ive never said to tune a motor lean to cool it down, i was describing what happpens when you go real lean by accident, or a major fuel issue. real lean is not the issue, its leaner than optimum, and near Stoich. a lot leaner cools things off, and even leaner than that, thing dont run very well. (both loose a bunch a power too).
Dont worry, the List Motor will be tuned to near 12.5:1. Your worried about a guy that has made a stock S4 motor last for over 100 racing hours? Trust me, the things i do always revolve around longevity!
mk
Dont worry, the List Motor will be tuned to near 12.5:1. Your worried about a guy that has made a stock S4 motor last for over 100 racing hours? Trust me, the things i do always revolve around longevity!
mk
No - I never mentioned compression ratio - that is yet another piece of the puzzle.
I agree 100% with your post & it's very informative, but telling someone with a boosted motor to lean it out to cool down the charge is misleading and that is what Mark said that I was addressing.
I guess for me (and I know other people due to message's I have recieved) it worries me to see posts like this coming from Mark who is about to tune a very expensive race motor this forum paid for.
I agree 100% with your post & it's very informative, but telling someone with a boosted motor to lean it out to cool down the charge is misleading and that is what Mark said that I was addressing.
I guess for me (and I know other people due to message's I have recieved) it worries me to see posts like this coming from Mark who is about to tune a very expensive race motor this forum paid for.
05-09-2008, 01:54 PM
#172
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Mark "Your worried about a guy that has made a stock S4 motor last for over 100 racing hours?"........ running something longer and longevity are not the same....running with KNOWN broken cam chain gear teeth and no oil in the tensioner ???? Other than possibly the OIL what have YOU done to make that "stock" engine last longer? I really would like to know.
05-09-2008, 02:01 PM
#173
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Mark "Your worried about a guy that has made a stock S4 motor last for over 100 racing hours?"........ running something longer and longevity are not the same....running with KNOWN broken cam chain gear teeth and no oil in the tensioner ???? Other than possibly the OIL what have YOU done to make that "stock" engine last longer? I really would like to know.
05-09-2008, 02:26 PM
#175
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Its a pretty long list Jim. I check the belt tension often, i keep the oil a little bit above full, and use amsoil which has shown me that it keeps pressure up at 250F oil temps.(and it never dips, even with 1.5g turns) I also drive the car in such a way that the engine is not banging off the rev limiter (but close), I dont miss-shifts (well,one time it did see 7+k) 
and also make sure that it never sees the track, unless the engine is heat soaked before hand (something no one else around me seems to do). I also dont 'rev' the engine upon warm up, something others around the race track seem to like to do.
I ran known broken cam teeth, but i did so because none of the 2 teeth missing were adjacent, (the forces were only 15% greater on the tooth that was next to the missing one based on gear sprocket experts) but as soon as l lost 3 teet on a sprocket, i turned the cams in. remember, i got 2 full racing seasons out of the engine with broken cam teeth. when I lost about 5 more teeth, I knew my "luck" had run out.
All in all, its not just this engine either. if you recall, i ran a stock 84 with a blown head gasket for over 170k miles and 40k of that was on the track! I also ran my part euro 5 liter for a full season.
Scot's engine i built, lasted for a full racing season as well (5 liter part euro) with no accusump, no oil cooler, (not even the stock one) or anything other than the stock stuff. And, he just ran a 1:40.3 out at laguna seca in qualifying, so he is no slouch now. That motor is bone stock, and is running Amsoil. I would think the single most important factor that has helped us with the 928 in a racing environment is the oil. I just dont think im that lucky of a guy!(but i did stay at a holiday inn once!)
Does anyone have more track time with a stock 928 engine than me? thats 6 full racing seasons, 96 race days, never missing a seasons race, a few extra races during those seasons, and no DNFs. Kind of a tough record to argue with in my opinion. However, i will say that it borders on miraculous.
Mk
and also make sure that it never sees the track, unless the engine is heat soaked before hand (something no one else around me seems to do). I also dont 'rev' the engine upon warm up, something others around the race track seem to like to do. I ran known broken cam teeth, but i did so because none of the 2 teeth missing were adjacent, (the forces were only 15% greater on the tooth that was next to the missing one based on gear sprocket experts) but as soon as l lost 3 teet on a sprocket, i turned the cams in. remember, i got 2 full racing seasons out of the engine with broken cam teeth. when I lost about 5 more teeth, I knew my "luck" had run out.
All in all, its not just this engine either. if you recall, i ran a stock 84 with a blown head gasket for over 170k miles and 40k of that was on the track! I also ran my part euro 5 liter for a full season.
Scot's engine i built, lasted for a full racing season as well (5 liter part euro) with no accusump, no oil cooler, (not even the stock one) or anything other than the stock stuff. And, he just ran a 1:40.3 out at laguna seca in qualifying, so he is no slouch now. That motor is bone stock, and is running Amsoil. I would think the single most important factor that has helped us with the 928 in a racing environment is the oil. I just dont think im that lucky of a guy!(but i did stay at a holiday inn once!)
Does anyone have more track time with a stock 928 engine than me? thats 6 full racing seasons, 96 race days, never missing a seasons race, a few extra races during those seasons, and no DNFs. Kind of a tough record to argue with in my opinion. However, i will say that it borders on miraculous.
Mk
Mark "Your worried about a guy that has made a stock S4 motor last for over 100 racing hours?"........ running something longer and longevity are not the same....running with KNOWN broken cam chain gear teeth and no oil in the tensioner ???? Other than possibly the OIL what have YOU done to make that "stock" engine last longer? I really would like to know.
05-09-2008, 02:34 PM
#176
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Stock?
Prove it. It's the Holbert High Speed Factory attempt 928, right?
05-10-2008, 01:11 AM
#177
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05-10-2008, 02:47 PM
#178
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05-10-2008, 02:54 PM
#179
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Prove it?? well, that was the rules for the world breaking speed record run at Bonneville in '86. There was more than enough power to do the deed, as the porsche engineers knew. my engine dyno matches a similar engine almost exactly. taking what i have apart shows that there is nothing really different, however we wont know what the engine looks like, until it comes apart in the coming months.
Now, there maybe a chance that the holbert car has some special oiling system, but that wouldnt explain my combined 160+ race days of reliability of my old part euro 5 liter, 4.7 US, as well as scots car by the way, the 2nd fastest stock blocked 928 5 liter ever to hit the track based on his times last race weekend.
Mk
Now, there maybe a chance that the holbert car has some special oiling system, but that wouldnt explain my combined 160+ race days of reliability of my old part euro 5 liter, 4.7 US, as well as scots car by the way, the 2nd fastest stock blocked 928 5 liter ever to hit the track based on his times last race weekend.
Mk
05-10-2008, 09:47 PM
#180
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Progress report:
I set up a wash manifold and blasted out the the glass bead material. This worked very well for the beads stuck in the valves. They sealed up well and I got a jump in compression. I could still hear air blowing by my rings when I did the leakdown test so I am assuming we have some damage to the cylinder walls.
I set up a wash manifold and blasted out the the glass bead material. This worked very well for the beads stuck in the valves. They sealed up well and I got a jump in compression. I could still hear air blowing by my rings when I did the leakdown test so I am assuming we have some damage to the cylinder walls.