The largest and best supported Jaguar cars enthusiast site on the Internet!

Serving Enthusiasts since 1993
The Jag-lovers Web

Currently with 3,166 members

Compression for the 8:1 Engine

Compression for the 8:1 Engine

Neil Young

Per Stenius asked:

Here is a quick question regarding the Series 1 6cyl engine: I have an engine marked with 'S' which the owner's manual claims stands for standard, which I presume was 8:1 compression ratio. The owner's manual says the markings used were /8 and /9 or, later, S and H (standard, high). The factory manual says the markings used were L and S, however. Nigel Thorley's book seems to mention all three, ie. L, S, and H. Does anyone know what these three designations mean, and specifically, was the S indeed 8:1? Also, some years ago, before the PO did a valve job on the engine, a compression test was done with the results 135 115 135 145 140 145 What should this result be for a 'new' engine with the S marking? I suppose doing a valve job also changes these readings quite a bit? The engine runs nicely as it is, I just got curious about this... Thanks.

These compression pressures are for the 'S' (standard) 8 to 1 compression engine. Yes, 'S' DOES mean 8:1.

Expect an even 145 psi when the engine is in very good condition (low miles). Should hold at least 125 psi for some years.

Please show your support for Jag-lovers by purchasing a set of our Car Stickers and don't forget to tell your friends about them! See our unique scanned collection of Brochures and other memorabilia
from the 1930s onwards! Currently over 260 entries...


Please help support the move to the new site, and DONATE what you can.
A big Thank You to those who have donated already!



Go to our Homepage
Improve your Jag-lovers experience with the Mozilla FireFox Browser!

  View the latest posts from our Forums via an RSS Feed!

Jag-loversTM Ltd / JagWEBTM 1993 - 2023
All rights reserved. Jag-lovers is supported by JagWEBTM
For Terms of Use and General Rules see our Disclaimer
Use of the Jag-lovers logo or trademark name on sites other than Jag-lovers itself in a manner implying endorsement of commercial activities whatsoever is prohibited. Sections of this Web Site may publish members and visitors comments, opinion and photographs/images - Jag-lovers Ltd does not assume or have any responsibility or any liability for members comments or opinions, nor does it claim ownership or copyright of any material that belongs to the original poster including images. The word 'Jaguar' and the leaping cat device, whether used separately or in combination, are registered trademarks and are the property of Jaguar Cars, England. Some images may also be Jaguar Cars. Mirroring or downloading of this site or the publication of material or any extracts therefrom in original or altered form from these pages onto other sites (including reproduction by any other Jaguar enthusiast sites) without express permission violates Jag-lovers Ltd copyright and is prohibited
Go to our Homepage
Your Browser is: CCBot/2.0 (, IP Address logged as on 4th Jun 2023 13:29:16