Rebuild time(?)
10-04-2021, 05:51 AM
#16
Rennlist Member
Switching sides is an excellent idea. The exhaust side takes quite a bit more of a beating than the intake. (I'm curious: did they both measure 67mm?)
10-04-2021, 07:51 AM
#17
Racer
Thread Starter
10-04-2021, 08:25 AM
#18
Racer
Thread Starter
Manufacture date of 2000 so they're not young but they are factory mounts so they can probably live another few years if not in the current budget. Switching sides would be helpful to extend the life as the exhaust side suffers more. Replacement later, although not fun, does not require engine out.
10-04-2021, 08:35 AM
#19
Rennlist Member
If the budget does allow, you'll definitely save a chunk of effort by doing them now (or even just doing the exhaust side now).
10-04-2021, 08:41 AM
#20
Racer
Thread Starter
I have some other things to sort out before this decision has to be made on the mounts, but I’m tending to agree. Appreciate the guidance!
Have to get the block and head sorted. Hope to get those moving ahead this week. And turbo to Evergreen. Injectors either cleaned or replaced with a little higher lb rating to accommodate Vitesse MAF in the future.
Im leaning toward either the OE mounts or Lindsey Ultra Mounts. Any experience with those?
Have to get the block and head sorted. Hope to get those moving ahead this week. And turbo to Evergreen. Injectors either cleaned or replaced with a little higher lb rating to accommodate Vitesse MAF in the future.
Im leaning toward either the OE mounts or Lindsey Ultra Mounts. Any experience with those?
10-04-2021, 11:28 AM
#21
Rennlist Member
"Im leaning toward either the OE mounts or Lindsey Ultra Mounts. Any experience with those?"
I went through this agonizing decision too lol. I purchased the Lindsey mounts but ultimately changed my mind and just payed for the Porsche OEM (hydraulic). I read up (Googled) on the science of hydraulic mounts, not just Porsche but hydraulic mounts in general. Turns out there is a lot of science there, who knew, meaning they are not just a gimmick lol. And also, maybe I'm just getting to old but I didn't want to deal with the vibrations anymore. The hydraulic ones are awesome. Makes a HUGE difference. I would say just by my own non scientific estimate, it cuts down on maybe 80% of vibrations sitting at stop light. Loved them so much I purchased a set for my 86 NA that I'm doing a engine reseal job on.
Again, didn't get to drive the Ultra Mounts but I did have worn out mounts on my 951 and plain cheap solid rubber ones on my NA. So I can tell you the difference between those and new OEM is big. The NA ones got so bad I was getting a headache driving it. Again, a lot of science when it comes to frequencies and vibrations, even ones you don't feel.
I can see the Ultra Mounts being useful for a track car though. Mine is a daily driver so I went with comfort. But yes they are expensive.
BTW, still have the Ultra Mounts if you are interested.
I went through this agonizing decision too lol. I purchased the Lindsey mounts but ultimately changed my mind and just payed for the Porsche OEM (hydraulic). I read up (Googled) on the science of hydraulic mounts, not just Porsche but hydraulic mounts in general. Turns out there is a lot of science there, who knew, meaning they are not just a gimmick lol. And also, maybe I'm just getting to old but I didn't want to deal with the vibrations anymore. The hydraulic ones are awesome. Makes a HUGE difference. I would say just by my own non scientific estimate, it cuts down on maybe 80% of vibrations sitting at stop light. Loved them so much I purchased a set for my 86 NA that I'm doing a engine reseal job on.
Again, didn't get to drive the Ultra Mounts but I did have worn out mounts on my 951 and plain cheap solid rubber ones on my NA. So I can tell you the difference between those and new OEM is big. The NA ones got so bad I was getting a headache driving it. Again, a lot of science when it comes to frequencies and vibrations, even ones you don't feel.
I can see the Ultra Mounts being useful for a track car though. Mine is a daily driver so I went with comfort. But yes they are expensive.
BTW, still have the Ultra Mounts if you are interested.
10-05-2021, 11:14 PM
#22
Racer
Thread Starter
Alright… changing gears. I picked up a block today. It wasn’t what I was looking for really, but I figured what the hell. There is no perfect option when it comes to fixing this debacle. This is an 86 951 block that was bored and steel sleeved, but never installed. A quick harbor freight measurement of the inside diameter showed around 103.5 mm. I’m assuming they are really 104 mm, and plan to take the block at the machine shop for a better measurement and a once over when I take in the head to be redone. Anyway, this block had been passed around a bit as part of an apparently stalled project. Price was right. Hopefully this was a wise decision. We shall see.
at one point I was thinking of increasing displacement with sleeves, until the cost of the sleeves scared me off. Anyway, like I said, the price was reasonable, but I’m seeing new pistons are costly. Either way, here we go!
I’m hoping for some guidance on a build with this block. When you go to a 104 mm bore for a street car, what else needs to change besides of course the pistons? Can a stock 951 head work without modification? Head gasket? I’m assuming chips need to be recoded, or go to something like MAF. Injector size? Am I missing anything else that needs to be modified or changed?
at one point I was thinking of increasing displacement with sleeves, until the cost of the sleeves scared me off. Anyway, like I said, the price was reasonable, but I’m seeing new pistons are costly. Either way, here we go!
I’m hoping for some guidance on a build with this block. When you go to a 104 mm bore for a street car, what else needs to change besides of course the pistons? Can a stock 951 head work without modification? Head gasket? I’m assuming chips need to be recoded, or go to something like MAF. Injector size? Am I missing anything else that needs to be modified or changed?
Last edited by Glue Guy; 10-05-2021 at 11:16 PM.
10-06-2021, 09:28 AM
#23
I would be concerned about the structural integrity of a 100mm bore block that is bored to accept steel sleeves with a 104mm bore.
Are there photos of the new block showing the sleeve type?
Are there photos of the new block showing the sleeve type?
10-07-2021, 01:36 PM
#25
Photos are not high enough resolution to see much other than that they are straight sleeves, without flanges and that the block does not appear to have been filled.
Does the block have the matched crank girdle and balance shaft housings?
Does the block have the matched crank girdle and balance shaft housings?
10-07-2021, 03:47 PM
#27
10-08-2021, 08:32 AM
#28
Racer
Thread Starter
I took the sleeved block first to a local Porsche guru mechanic, then to my machine ship yesterday, along with the head which is there for rebuilding.
the machine shop gave the block a thumbs up, minus correction of that bend at the bottom, and wanting to put flanges on the bottom of the sleeves. The bores are 104mm, and consistent around the bores. It appears to be a good base for a 2.7 build, though I would prefer to have a support plate on top.
the NA block also looks pretty good.
plan to replace all seals and bearing in one or the other, along with pistons and pins if I go with the 2.7.
my plan is to pull the turbo pistons from my old block, and those from the NA block, to see what we are dealing with. Will make a decision from there.
the machine shop gave the block a thumbs up, minus correction of that bend at the bottom, and wanting to put flanges on the bottom of the sleeves. The bores are 104mm, and consistent around the bores. It appears to be a good base for a 2.7 build, though I would prefer to have a support plate on top.
the NA block also looks pretty good.
plan to replace all seals and bearing in one or the other, along with pistons and pins if I go with the 2.7.
my plan is to pull the turbo pistons from my old block, and those from the NA block, to see what we are dealing with. Will make a decision from there.
10-10-2021, 12:32 AM
#29
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Slippery slope
So the original poster asked for my input:
a dry sleeved 104 bore 2.5 has very thin sleeves in a very thin alusil bore. Not a big fan. Many have made it work over the years but many more have failed. Not knowing who did the work adds to my concerns.
the catch is that you have to spend a bunch of $ on custom pistons, bearings and gaskets so using an unknown block is too risky for me. I see two choices: nikasil coat your existing block ($800 or so) and put it back together with new rings and bearings or jump in the deep end and go to a 3.0
the 2.7 middle ground never really made sense to me since you are spending all the same $ except fir the 3.0 crank.
a dry sleeved 104 bore 2.5 has very thin sleeves in a very thin alusil bore. Not a big fan. Many have made it work over the years but many more have failed. Not knowing who did the work adds to my concerns.
the catch is that you have to spend a bunch of $ on custom pistons, bearings and gaskets so using an unknown block is too risky for me. I see two choices: nikasil coat your existing block ($800 or so) and put it back together with new rings and bearings or jump in the deep end and go to a 3.0
the 2.7 middle ground never really made sense to me since you are spending all the same $ except fir the 3.0 crank.
10-10-2021, 08:53 AM
#30
Racer
Thread Starter
Thank you, Chris! And thanks to everyone for your input!
I see installing a questionable block that fails as a worst case scenario for me with this. I’m in SC, but can ship the block if necessary. Any recommendations on a company to recoat and get it back to original specs?
I see installing a questionable block that fails as a worst case scenario for me with this. I’m in SC, but can ship the block if necessary. Any recommendations on a company to recoat and get it back to original specs?