2019 Engine Rebuild Comparison RND/FSI/EBS/Vertex
04-30-2019, 10:56 AM
#31
The problem is, there is no objective data on the relative reliability of any of these solutions (or on the factory engine, for that matter). The shops who install iron sleeves may genuinely have never seen one of their sleeved blocks fail, but it could happen at a later date and it might happen to other builders. The shops who who fix iron sleeved engines by replacing them with nikasil-aluminum sleeves would only see failed engines, so they don't have any idea how many engines are successfully rebuilt with iron sleeves (reverse survivorship bias).
There isn't clear consensus on this topic, or good data, and that's what makes the decision difficult.
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RobertM525 (03-10-2022)
04-30-2019, 11:02 AM
#32
Definitely agree with point #1.
04-30-2019, 11:31 AM
#34
Rennlist Member
I've read a lot on the topic of different sleeve types and have discussed this on other threads. Folks who install iron sleeves will tell you their builds hold up well in the long-term for both commuting and even multiple seasons of racing. Folks who sell nikasil-plated aluminum sleeves will tell you they see engines where the iron sleeves shift due to thermal expansion causing problems. The iron sleeve manufacturers say that only happens if they're installed improperly.
The problem is, there is no objective data on the relative reliability of any of these solutions (or on the factory engine, for that matter). The shops who install iron sleeves may genuinely have never seen one of their sleeved blocks fail, but it could happen at a later date and it might happen to other builders. The shops who who fix iron sleeved engines by replacing them with nikasil-aluminum sleeves would only see failed engines, so they don't have any idea how many engines are successfully rebuilt with iron sleeves (reverse survivorship bias).
There isn't clear consensus on this topic, or good data, and that's what makes the decision difficult.
The problem is, there is no objective data on the relative reliability of any of these solutions (or on the factory engine, for that matter). The shops who install iron sleeves may genuinely have never seen one of their sleeved blocks fail, but it could happen at a later date and it might happen to other builders. The shops who who fix iron sleeved engines by replacing them with nikasil-aluminum sleeves would only see failed engines, so they don't have any idea how many engines are successfully rebuilt with iron sleeves (reverse survivorship bias).
There isn't clear consensus on this topic, or good data, and that's what makes the decision difficult.
04-30-2019, 03:02 PM
#35
Based on suggestions here, I've updated the spreadsheet with a row that compares turnaround time where I have that information. Obviously, that is a factor that will change over time, and I've noted that in comment on the sheet.
I've also included EBS racing variations for nikasil plating and Nickies sleeves, for cost comparison on just that one dimension.
I've also included EBS racing variations for nikasil plating and Nickies sleeves, for cost comparison on just that one dimension.
04-30-2019, 05:22 PM
#36
Rennlist Member
I can't find anyone who even wants to give me an estimate on swapping out a shortblock. Consensus seems to be that it costs about the same as a rebuild and leaves you with worn out heads and a block that's still susceptible to bore scoring and d-chunking down the line. Plus, no warranty on the engine.
Quote from a high-end indy shop in Chicago:
"Yeah, it's not a good option. The labor cost would increase substantially, as these motors require a lot of attention to detail. not to mention the cost of new chains, guides, head gaskets, etc. I think the cost would probably be the same, if not more, to just have the motor rebuilt as a whole. Also, consider that rebuilding the motor as a whole would most likely be backed by a warranty."
Quote from Charles at LN on another thread here:
"It's damn near criminal to take the heads off an engine and reuse all these used parts on a new shortblock. Wasted labor and a recipe for disaster. The heads always need rebuilding and there are lots of other pieces that need to be changed that aren't included in the shortblock. Just saying."
Quote from a high-end indy shop in Chicago:
"Yeah, it's not a good option. The labor cost would increase substantially, as these motors require a lot of attention to detail. not to mention the cost of new chains, guides, head gaskets, etc. I think the cost would probably be the same, if not more, to just have the motor rebuilt as a whole. Also, consider that rebuilding the motor as a whole would most likely be backed by a warranty."
Quote from Charles at LN on another thread here:
"It's damn near criminal to take the heads off an engine and reuse all these used parts on a new shortblock. Wasted labor and a recipe for disaster. The heads always need rebuilding and there are lots of other pieces that need to be changed that aren't included in the shortblock. Just saying."
You should get the quote for the factory shortblock install from a Porsche Service Center, include the cost of reconditioning the heads also. If done at a Porsche center there will be a warranty on parts and labor.
The expansion rate for aluminum vs ductile iron is different, but there are different aluminum's and ductile irons. Adding silicon to aluminum (Alusil, Lokasil ect) decreases the expansion rate of the aluminum depending on the percentage. The higher the percentage the less the expansion. I am not a metallurgist, but I have read that it is possible to have an aluminum alloy and ductile iron with the same expansion rate.
05-01-2019, 12:47 AM
#37
Former Vendor
Lots of critical items are left out of the comparison spreadsheet... Items like graded, and coated bearings, what piston rings are used, what exactly is done to the cylinder heads, and etc are just a few of the missing links.
05-01-2019, 01:41 AM
#38
I've added comments to the cells on the spreadsheet denoting the type of pistons, rings, and rod bearings, where I have that information. If you want to let me know what kind of rod bearings are used in the FSI builds, I will add them. The spreadsheet is open to comments, so you're also welcome to add them yourself.
I have a row for head refinishing (valve job, surfacing). What else is missing in terms of cylinder heads?
I appreciate your expert input into making this an accurate comparison. Thanks!
05-01-2019, 09:44 AM
#39
Rennlist Member
The fact that Iron expands and contracts at a different rate than the parent material surrounding it (Aluminum) is really all the data I need to tell me that Aluminum sleeves with Nikasil plating are superior to Iron. 10% is a worthwhile up-charge in my book, as a failure down the road will wind up costing much more...
05-01-2019, 10:06 AM
#40
Burning Brakes
new valve guides
new valve seats
new valve springs
also thinking about combustion chamber volume measurement/equalization.
05-01-2019, 10:20 AM
#41
Rennlist Member
We are members of the AERA Engine Builders Association and there was an article a while back about sleeving aluminum blocks, in particular Alusil Audi V8 (however they do show a photo of an M96 block in the article).
Commonly a cast ductile iron sleeve in an alloy block, like an LS engine, requires .002-.003" interference and the block is heated and sleeves chilled prior to installation. When this was attempted with the Alusil block, the block cracked between all the cylinders on one bank.
Through trial and error, they found that they need to reduce the interference to .0005"-.001" to not crack the block, again, per the article.
What I find interesting is that they said that they heated the block to 155F which would open the block up .0008-.0012", which "to our delight, each of the sleeves dropped in quite nicely."
This backs up what I have seen in blocks that we're re-sleeved with Nickies after being done with steel sleeves.
Either the sleeves can move during operation, which in fact we've actually seen them rotate (see above) or they fall out of the block in our ultrasonic which is heated to 180F.
We've also found blocks that were cracked and not salvageable after having been sleeved with steel/iron sleeves as well, like what was mentioned in the AERA article.
05-01-2019, 10:27 AM
#42
Rennlist Member
Beyond the weight reduction and increased efficiency an all-aluminum engine provides, one of the reasons why OEMs have gone to all aluminum engines without sleeves is to reduce the bore spacing and also allow for larger bores within those constraints.
That's why some blocks take to traditional steel/cast iron sleeves better than others.
05-01-2019, 10:44 AM
#43
Rennlist Member
There is a lot of information on this forum (and others) about rebuilding 996 engines, but much of it is several years old or UK-centric. I've spent a considerable number of hours researching options for rebuilding my '99 996 engine and collecting my notes into a comparison spreadsheet. Despite the inevitable arguments that will ensue about various approaches to rebuilding these motors, I'm going to share it to help others who are in my unfortunate predicament.
Some background, caveats, and assumptions:
1. My car has bore scoring which enables/requires different rebuild approaches than IMS or other failure modes.
2. I'm located in Chicago, and shipping costs reflect my location.
3. I decided to only compare engine rebuild specialists and not general shops that offered to do the rebuild.
4. Engine removal & installation costs reflect the best quote I received from a Porsche specialty shop in the Chicago area, but I got quotes for more than twice that amount.
5. I left blank any part replacements I could not confirm. I have detailed proposals from some vendors but relied on public information for others. Which is to say, some of the parts left blank might actually be included in those builds.
M96 Engine Rebuild Comparison Spreadsheet
I'm certainly missing some things in the comparison. Your constructive comments are welcome here, and you can also add comments (but not edit) any of the cells in the spreadsheet.
Some background, caveats, and assumptions:
1. My car has bore scoring which enables/requires different rebuild approaches than IMS or other failure modes.
2. I'm located in Chicago, and shipping costs reflect my location.
3. I decided to only compare engine rebuild specialists and not general shops that offered to do the rebuild.
4. Engine removal & installation costs reflect the best quote I received from a Porsche specialty shop in the Chicago area, but I got quotes for more than twice that amount.
5. I left blank any part replacements I could not confirm. I have detailed proposals from some vendors but relied on public information for others. Which is to say, some of the parts left blank might actually be included in those builds.
M96 Engine Rebuild Comparison Spreadsheet
I'm certainly missing some things in the comparison. Your constructive comments are welcome here, and you can also add comments (but not edit) any of the cells in the spreadsheet.
I would also like to clarify that on the RND engines, new intake lifters are fitted except with variable lift (Variocam Plus) intake lifters, where those are inspected for wear and cracks, and replaced only if necessary, and at cost.
RND does also offer direct plating for certain m-codes where the cylinders are less prone to failures, so that would be a cost savings.
I also would to point out that in Vertex's price, new sleeves and pistons are not included. If you read their website closely, it says the pistons are checked and re-ringed. Anything beyond that costs more.
05-01-2019, 10:50 AM
#44
For combustion chamber work, is that getting into the realm of porting, polishing, etc? I don't think that level of work is included in any of the builds at this price point.
05-01-2019, 10:57 AM
#45
Rennlist Member
@Coopduc Thanks for the suggestions. Valve guides are already included on the spreadsheet. I added a row for valve springs, and one for valve stem seals, which are listed as included for at least some of the builds in the comparison. Are "valve seats" and "valve stem seals" interchangeable terms, or do they refer to different parts?
For combustion chamber work, is that getting into the realm of porting, polishing, etc? I don't think that level of work is included in any of the builds at this price point.
For combustion chamber work, is that getting into the realm of porting, polishing, etc? I don't think that level of work is included in any of the builds at this price point.
As far as seats, with these engines the intake seats on the 3 chain heads are the ones that are known to come loose and cause catastrophic failures. We replace them on RND rebuilds as well as the guides. Exhaust seats usually do not need to be replaced.
Valve springs are checked and replaced only if needed.
