Engine Question/Opinions for Tii Purists

[Simeon]

If you were really concerned about a numbers matching block in 100,000 miles time then putting sleeves in the block will be a small deal. The problem will be then finding the right pistons in stock sizes. 

[Conserv]

30 minutes ago, Simeon said:

If you were really concerned about a numbers matching block in 100,000 miles time then putting sleeves in the block will be a small deal. The problem will be then finding the right pistons in stock sizes. 

 

And, Simeon,

 

This is a spare engine out of a '74 tii, so obviously not original to Paul's '73 tii...

 

Best regards,

 

Steve

 

[Simeon]

38 minutes ago, Conserv said:

 

And, Simeon,

 

This is a spare engine out of a '74 tii, so obviously not original to Paul's '73 tii...

 

Best regards,

 

Steve

 

 

Just a general observation and not directed at Paul.

 

I wish I could lay my hands on a spare engine to rebuild in parallel to driving my car. 

[Son of Marty]

In Steve's scenario of the 2 identical cars I would take the one with the cast pistons over the forged hands down for a street or club track car why put up with the piston slap during warm up, however the link to Ireland is for there cast 9.5/1 pistons and their I might weigh the cost vs oem vs originality in a whole diferant light.

 

Just my opinion, it's worth every thing you payed for it.   

Edited December 1, 2016 by Son of Marty

[jgerock]

I'm already at the 2nd oversize (bore) on my 73tii "numbers matching block" AND the original cylinder head is close to the minimum thickness.  Am I worried - heck no.  Runs great. These cars are meant to be driven and enjoyed. 

 

 

 

 

 

 

Well - I did buy the spare 72tii engine as a back up for the 73 - but now that engine is in the 69.

 

 

 

I do have a spare block from a 70.

 

 

 

I may have a problem.

[Conserv]

4 hours ago, Son of Marty said:

In Steve's scenario of the 2 identical cars I would take the one with the cast pistons over the forged hands down for a street or club track car why put up with the piston slap during warm up, however the link to Ireland is for there cast 9.5/1 pistons and their I might weigh the cost vs oem vs originality in a whole diferant light.

 

Just my opinion, it's worth every thing you payed for it.   

 

Let me be the first to point out that I apparently answered the wrong question.  I thought this was a question regarding (a.) brand (OEM vs. aftermarket), and, possibly, (b.) compression ratio (9.0 vs. 9.5).  I knew not that the 9.5 CR I.E. piston was 90mm and available in cast and forged versions.  (The link is to the cast version.)  My bad: I should have asked for more information.  The question, it turns out, regards (c.) bore (stock plus the usual oversizes vs. 90mm), and (d.) piston manufacturing method (cast vs. forged).

 

With all of that said, can we quantify -- okay, guess -- how much one might value two otherwise identical cars, one with Mahle 9.0 first-oversize pistons, the other with the I.E., 9.5, 90mm forged pistons?  The same?  $5 more for one?  $500 more for one?  $5,000 more for one?

 

Regards,

 

Steve

 

 

 

Edited December 1, 2016 by Conserv

[Son of Marty]

Well C is harder to answer, the stock 1st over could be rebuilt again where the 90mm you would probably have to sleeve to rebore, but how many more times are you likely to rebuild an engine on a perfectly restored Tii, it's not going to get that many miles on in most cases. As to forged or cast I would prefer the cast piston for a street engine unless it was boosted or extremely hopped up and driven that way. Don't get me wrong forged piston have their uses, but they also have their own set of baggage. as for which Tii would be worth more, I don't know but I would like to see two perfect and consecutive numbers Tii's side by side.

[JohnH]

7 hours ago, PaulTWinterton said:

Everything else is stock, although Wes Ingram recommends adjusting the rebuilt KFish for the slightly higher displacement.

 

 

Which makes sense since the engines capacity will now be 2035 cc (because we have increased the bore from 89 to 90mm.

[NYNick]

In the air cooled Porsche world, engine (and suspension) changes and improvements that can't be seen but can be felt constitute zero and maybe even a bump to value. Of course, you always have the nut job purists who think you should have floor mats over your original floor mats to preserve your floor mats originality. They would gag that you would ever consider boring and engine and would scoff at such blasphemy.

 

Nobody here feels like that right? (did you just flinch Steve?) LOL.

 

Nick

[danco_]

Engine builder of my car claims to have installed euro tii pistons at a CR of 10:1. 

 

Everyone is stating 9.5:1 is euro CR, but I also hear stories of 10:1 early 72 tii US cars.

 

 

What is real anymore?

 

 

[saaron]

On 11/30/2016 at 3:21 PM, PaulTWinterton said:

Are the Ireland forged 9.5:1 pistons an upgrade to the tii engine or would they be considered an "un-original" modificaton? 

 

Everything else is stock, although Wes Ingram recommends adjusting the rebuilt KFish for the slightly higher displacement.

 

Based on this, and the rest of this thread, I don't see this as a big deal.  It's like, "I have to do a rebuild, the block is being bored out, and while I was in there, we bumped up the compression ratio a half a point to sync up with what the euro cars had."  

 

Boring out the block to me is a necessity - that's not really a decision to be made; you have to do it.  Your decision around raising the compression ratio a bit seems sane and reasonable, and isn't massively deviating from anything factory.  It's not like you're putting 13:1 in there.  It wouldn't phase me at all if I was thinking about buying a car and the engine was rebuilt that way.  That's my opinion.

 

And Ryan, I'm too lazy to go look it up in the Blue Book, but I think the earlier-head (121/121ti was it?) tiis w/the plastic runners had 10:1 CR, whether US or Euro.  They were both the same (I think).  When the switch to the E12 head /aluminum runners happened somewhere in spring '72, the US cars went to 9:1 and the Euro cars were 9.5:1.  That's how I remember reading about it in various reference pubs.

 

So someone from your car's past saying your car has "euro 10:1 pistons" is sort of getting partial credit, I guess.  Both the euro AND US early tiis had 10:1.  If it was an E12 car, and it had 10:1 pistons put in it, that would represent an increase in the compression ratio vs. stock 9:1 or 9.5:1 (depending on your car's intended region).  I think the point of that person's comment was - we raised up the compression ratio vs. stock (assuming your car had the E12 head).

 

Again, my recollections can be confirmed in the blue book and Maccartney reference.   If I have the facts messed up, I will go back and edit.  I don't want to add to confusion.  

 

EDIT:  I get partial credit but was wrong...see below post...

 

Scott

Edited December 1, 2016 by saaron

[visionaut]

6 hours ago, danco_ said:

I also hear stories of 10:1 early 72 tii US cars.

 

My understanding is BMW OEM M10 pistons only ever went to 9.5:1 compression, for the Euro tii and ti models (in both 121 and E12 head variants).  And 10:1 was only an option from Alpina...

 

*edit* correction:  According to the BMW 2002 Service Manual, early 1971 non-USA LHD 2002tii from VIN 2700001 thru 2710839 were equipped with 10:1 compression pistons (121 head).

 

FWIW, I'm running 90mm oversize, 9.5:1 OEM Mahles (E12 head).

 

I don't think one would voluntarily choose to go to a larger overbore than is necessary for a rebuild unless one was specifically looking to increase displacement. (if considering a subsequent rebuild on that same block is a factor). So if 1st oversize would work, I'd go for that.

 

Edited December 1, 2016 by visionaut
corrected for OEM 10:1

[saaron]

2 hours ago, visionaut said:

*edit* correction:  According to the BMW 2002 Service Manual, early 1971 non-USA LHD 2002tii from VIN 2700001 thru 2710839 were equipped with 10:1 compression pistons (121 head).

 

So I guess the early USA ones, with the 121 head, never got 10:1, then?  So Ryan's seller folklore about his E12 head car would make sense - they put 10:1 euro pistons in it, even though only 839 euro cars had it.

 

Scott

Edited December 1, 2016 by saaron

[danco_]

1 hour ago, saaron said:

 

So I guess the early USA ones, with the 121 head, never got 10:1, then?  So Ryan's seller folklore about his E12 head car would make sense - they put 10:1 euro pistons in it, even though only 839 euro cars had it.

 

Scott

I've got an e12 head last time I checked. I spoke with the engine builder two or so weeks ago and he is certain he added 10:1 euro tii pistons and a 284 Schrick Camshaft, along with lightened and balanced rods and other noteworthy things. He remembers vividly because of who owned the car at that particular time. Says he'll never forget this car. 

 

[visionaut]

1 hour ago, saaron said:

 

So I guess the early USA ones, with the 121 head, never got 10:1, then?  So Ryan's seller folklore about his E12 head car would make sense - they put 10:1 euro pistons in it, even though only 839 euro cars had it.

 

Scott

 

That's 10839 Euro 2002tiis that came so equipped - almost 1/2 (!) of the total 20114 such Euro LHD Model 71 tii produced from 4/71 to 8/73.  So maybe not so limited if they were used for half the production.

 

They were only for the 121, not for the later E12 heads.

And yes, none in the early Model 71 USA LHD tii models, which have VINs 2760001 & up.  (4521 USA LHD Model 71 tii produced from 8/71 - 8/73).

 

The OEM 10:1 pistons would be by either KS or Mahle, and would obviously be stock sized (88.96, 88,97 or 88.98).  Not sure how many they would have produced for oversize replacement needs, though from a parts search it looks as if they only produced them in up to second oversize (+0,50).

 

Tom