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2.1 high boost m10


retoropak

Question

I am planning to build my m10 this summer. I will be shooting for 400whp on e85

 

I have two options.

 

Option 1 using 92x82 vw type 1 pistons and s14 rods

 

Bore:92mm

Stroke:80mm

S14 Rods: 144mm

Deck height:217.5mm

Compression height:35mm

Headgasket thickness:1.5 or 1.8mm

Combustion chamber volume:63 cc

Compression ratio: 9.25:1

 

With this setup pistons will be sticking put approximately 1.5mm out of hole. With the 1.8mm gasket i should have 0.3mm clarance.

 

 

Or I could mill 1.5mm from top of the piston and zero deck it which will result in compression 8.25:1 ratio

 

Option 2 using 92x69 vw type 1 pistons and m10 rods

 

 

 

Bore:92mm

Stroke:80mm

M10 Rods: 135mm

Deck height:217.5mm- 2.7mm= 214.8

Compression height:39.8mm

Headgasket thickness:1.5 or 1.8mm

Combustion chamber volume:63 cc

Compression ratio: 8.25:1

 

I would have to deck the block 2.5-2.7mm to get it "zero decked"

 

 

What would you rather do? Deck the block and use shorter rods or mill the pistons and use longer rods?

 

Or maybe let the pistons stick out the holes and use 1.8mm gasket but it will give me only 0.3mm clearance.

 

 

 

 

Thanks

 

 

 

 

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I will never boost another engine with stock pistons. With very old used pistons you start off right away at a disadvantage being that the ringlands have been cycled and are closer to fatigue failure than new (as you know, aluminum doesn’t have an endurance limit)

Get some forged pistons and you can specify all the parameters you want to.


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I will never boost another engine with stock pistons. With very old used pistons you start off right away at a disadvantage being that the ringlands have been cycled and are closer to fatigue failure than new (as you know, aluminum doesn’t have an endurance limit)

Get some forged pistons and you can specify all the parameters you want to.




Thats the plan to get the vw type 1 forged JEs or Mahles.


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What boost? Lets assume i am building NA 100hp 2.1 liter m10 for now.

 

Lets get back to the question.

 

A. Deck the block to achieve zero deck

B. Mill the pistons to get the zero deck

C. Let the pistons poke out the block and use thicker HG

 

 

 

Also the reason for the vw type 1 pistons is that they are cheap.

 

$350-420 for a set of four forged mahles or JEs is really attractive when you compare it to a 800-1000 for a set of custom ones

 

 

 

 

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I would use the thicker headgasket.

If you are running e85 stick with the higher compression. 

If for whatever reason you want to switch it up you can always tear it down with the HG. Shaving the piston however you can not.

People may say you are doing it the hack way by using the thicker HG, but you are just doing it different than oem. There is more than one way to microwave a cat.

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3 hours ago, retoropak said:

How about milling 1.5mm from the piston? They are claiming the got some extra meat to allow for valve pockets

https://aapistons.com/collections/piston-liner-kits-sets/products/vw-92mm-2180cc-racing-forged-piston-kit


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Maybe... I'd want a drawing or something more to go on than the blurb.

If that's a picture of the actual kit, I'd check on the pins too. I know when you order custom pistons, you can choose different pins for lightweight/high rpm, or something a bit more stout for boosted applications.

Good luck with the project btw. I've read a lot about engine building over the years, but don't have much experience myself. Some day I'd like to get crazy with the cheez whiz and build something cool like this.

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Well instead of machining the top of the piston and the valve reliefs down I made a custom MLS head gasket to keep valve clearances tolerable. Also made longer dowels for the Cylinder head alignment. I am not ver familiar with the M10 engine. A few things to keep in mind is make sure you have The extra slack in the timing chain or belt. Try to keep enough clearance between the valves and piston for thermal expansion.


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Jeff has very solid advice here. Distance between crank and cam centerlines is quite critical in maintaining proper tolerances so your pistons do not eat the valves for lunch, preventing detonation during periods of high load with low(ish) RPM etc etc. 

Also, Get the Mahle or JE custom pistons, W do it right the first time and then smack the redline silly with the tach needle for years to come. Wiseco also makes a decent product. I opted for factory Goetze rings when putting my M30B34 back together and she purrs like a kitten. 

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