M20B25 compression without opening the engine?

[Coyote_ar]

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

[632 Regal]

9.7:1

[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.

[Rustam]

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

[632 Regal]

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

Appx .030 in

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

[Rustam]

Appx .030 in

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)

[Rustam]

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.

[Rustam]

Appx .030 in

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

Good stuff.

[Rustam]

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

[632 Regal]

Thicker gaskets can simply be purchased. Many choices here:

http://www.cometic.com/c-1280264-automotive-import-mls-head-gaskets.html

[Rustam]

Thicker gaskets can simply be purchased. Many choices here:

http://www.cometic.com/c-1280264-automotive-import-mls-head-gaskets.html
That's nice to know. Thank you for the info, Jeff.