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Yes; I have noticed that throughout the production years they added those holes later. The CMC assembly manual specified it. Wonder why some had it and some didn’t. In my case I followed recommendations from Gene Berg’s literature and added an air scoop in the right torsion bar area connected via a hose to a cut out hole on the front engine tin (right side of course; on doghouse motors the left side is totally taken by the hot air exhaust ducting from the oil cooler).

If you are going to bore case/heads for 90.5 mm then why not go max of 94 mm?  Both use same std 69 mm crank.  A 1776 cc is a pretty much a low stressed upgrade.  Seems once you go to 1915 cc, you end up with more heat so other improvements are needed (oil cooler).  Plus on a 94 mm bore the case stud threads are very near to the bored area (this doesn't seem to be a big issue - just looks concerning).

Volkswagen Engine Case Boring for 94mm Cylinders - YouTube

@WOLFGANG posted:

If you are going to bore case/heads for 90.5 mm then why not go max of 94 mm?  Both use same std 69 mm crank.  A 1776 cc is a pretty much a low stressed upgrade.  Seems once you go to 1915 cc, you end up with more heat so other improvements are needed (oil cooler).  Plus on a 94 mm bore the case stud threads are very near to the bored area (this doesn't seem to be a big issue - just looks concerning).

Volkswagen Engine Case Boring for 94mm Cylinders - YouTube

Right on; my ideal choice for a bigger displacement aircooled VW mill would be a 2007; 90.5 x 78.

Why? Thick-wall 92s are just as good as 90.5s. If I wasn't going to do 94 pistons, I'd do an 82 stroke.

Honestly, for the $400 Mahle 94s cost, it's cheap enough to replace them after 40,000-50,000 miles. I just did that last summer. It cost me $500 to get my heads re-done by Headmasters/Audirac in California, the original shop the heads came from. After a few gaskets and sealers I'm $1000 in, and it's brand new, again.

Everyone talks about longevity, but how many people put REAL miles on these cars, except for Musbjim? Why build for 100K, when you see 3-5K a year? Most of us are older than 50, I'm 56. I might have 30 years of driving, but realistically 20 years of getting in and out of a Spyder is optimistic. At 3K a year, I might see 60K more mileage, but I doubt it.

Again, I prefer Mahle over AA. AA are much cheaper($250?) but seem to get out of round quick.

@DannyP posted:

Why? Thick-wall 92s are just as good as 90.5s. If I wasn't going to do 94 pistons, I'd do an 82 stroke.

Honestly, for the $400 Mahle 94s cost, it's cheap enough to replace them after 40,000-50,000 miles. I just did that last summer. It cost me $500 to get my heads re-done by Headmasters/Audirac in California, the original shop the heads came from. After a few gaskets and sealers I'm $1000 in, and it's brand new, again.

Everyone talks about longevity, but how many people put REAL miles on these cars, except for Musbjim? Why build for 100K, when you see 3-5K a year? Most of us are older than 50, I'm 56. I might have 30 years of driving, but realistically 20 years of getting in and out of a Spyder is optimistic. At 3K a year, I might see 60K more mileage, but I doubt it.

Again, I prefer Mahle over AA. AA are much cheaper($250?) but seem to get out of round quick.

Great points; you are absolutely right. I am just going by what I’ve read and seen from the pros in terms of removing as less material as possible from block, heads while increasing displacement and using the thicker cylinder walls possible. But what you say is absolutely and irrefutably true. We never put that much mileage in these cars except El Guapo and we are not spring chickens either.

Last edited by Impala
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