M20B25 compression without opening the engine?

Hi guys, is there any way to know the compression ratio of the engine, without opening it?


My car was manufactured on nov 1988, its a euro 525i, no cat. Thanks for any help.




VIN info:


Vehicle Identification Number WBAHC210904237760
Type HC21
Model 525i - EUR
Development Code E34
Chassis LIM
Steering LL
Doors 4
Engine M20
Displacement 2.50
Power 125
Drivetrain HECK
Transmission AUT
Color Royalblau Metallic - 198
Upholstery Indigo Leder - 0293
Production Plant
Production Date 1988-11-14


Options
200 Katalysator - Entfall Katalysator - Entfall
226 Sports Suspension Settings Sportliche Fahrwerksabstimmung
314 Heated Windscreen Washer Nozzles Frontscheibenwaschduesen Beheizt
355 Laminated Glass Verbundverglasung
401 Sliding/vent Roof, Electric Schiebe-hebedach, Elektrisch
411 Window Lifts, Electric Fensterheber,elektrisch Vorn/hinten
498 Headrests In Rear, Mechanic. Adjustable Kopfstuetzen Im Fond
534 Automatic Air Conditioning Klimaautomatik
553 On-board Computer Iv W Remote Control Bordcomputer Iv Mit Fernbedienung
570 Stronger Electricity Supply Staerkere Stromversorgung
651 Bmw Bavaria C Reverse Bmw Bavaria C Reverse
823 Hot Climate Version Heissland-ausfuehrung
850 Add Fuel Tank Filling For Export Zusaetzl. Tankfuellung Export
856 Language Version Spanish Sprachversion Spanisch
925 Shipping Protection Package Versandschutzpaket

9.7:1

Sh*t, i thought so ... there goes my easy way to boost it. i guess ill add a thick MLS gasket to the shopping list.

thx for the reply.

Quote:

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Originally Posted by Coyote_ar

Sh*t, i thought so ... there goes my easy way to boost it. i guess ill add a thick MLS gasket to the shopping list.

thx for the reply.

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How thick would a gasket have to be to drop compression by 1 unit?

Quote:

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Originally Posted by Rustam

How thick would a gasket have to be to drop compression by 1 unit?

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Appx .030 in

Edit .030 is appx .5 points so .060 is around 1 point.

Quote:

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Originally Posted by 632 Regal

Appx .030 in

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Doesn't make sense. .03" is a hundredth of the piston's travel between TDC and BDC:
.03" = .75mm
M20 Stroke = 75mm = 100*.75
(Also had some beer so maybe thinking out of place. Would have to do normal calculations)

To lower compression to 8.0:1 for example, additional 2.1 MILLIMETERS must be provided. Got calculations, cannot upload through smartphone. Will upload once I get the computer connected to internet in another room.
SO, it seems Jeff, you ARE RIGHT. I should have calculated for 8.7:1 for a unit drop as I asked earlier, but it seemed that compression is not applealing as a turbochargeable one , so did 8.0:1 example.

Quote:

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Originally Posted by 632 Regal

Appx .030 in

Edit .030 is appx .5 points so .060 is around 1 point.

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Good stuff.

Have you consider making a gasket from a copper sheet, of agiven thickness? Must be annealed

Thicker gaskets can simply be purchased. Many choices here:

http://www.cometic.com/c-1280264-aut...d-gaskets.html

Quote:

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Originally Posted by 632 Regal

Thicker gaskets can simply be purchased. Many choices here:

http://www.cometic.com/c-1280264-aut...d-gaskets.html

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That's nice to know. Thank you for the info, Jeff.