I have no idea about the Series I engines, but the Series II share the same bottom end with one very large exception that should pertain to Series I also;

The compression ratios are different and of course the pistons differ.

All other reasons aside, it would be unwise to consider it based on pistons and compression alone.

Cheers,

Everything i've read said Series I was 8.5 on both N/A and */C.

Ah well that rules out my theory then .

Cheers,

Differing thoughts on this would tend to suggest there may be some risk involved. Even with the same compression ratio, there can still be some major differences.

I know of 2 MN members sorta looking for a series I L67 to tear into. We may be able to get some parts next to eachother if that happens.

I'll bring mine back here next time i'm at home... But they were given out as trophy'* to those who demo'd the engine.... Smellbird, Damemorder, allmachtige, and some others have one as well.

In reading the GM service manuals for 93, I have found the Compression Ration for the L27 is 8.5:1 whereas the L67 is 9.0:1. Other than that, I cannot see a difference based on specification. With this info, would it be possible to change the internals to get the block and crankshaft at the same compression in an L27 block as a L67? Would it would alright if the compression was lower as in it would be using the L27 without changing parts?

This is Straight from my 1993 Bonneville Service Manual

Service Manual Page

(edited by willwren for copyright)
Please don't post pics or scans of copyrighted material, particularly that material covered by GM copyrights.

FYI, the link showed a pic with the compression ratios:

8.5:1 for L67
9.0:1 for L27

(93 service manual)

-kind of following this topic along, just for interest. I'm wondering if you guys are going to find out that the supercharged engine has to have a lower "static" compression ratio, in order to survive under full boost?

(-that is certainly the case with all of the SC V-8'* I've ever been around.)

Hmm..where'* '93 in the mix? I assume same as '92.

If anyone can look at the pistons on a '94 l27 you should be able to tell. If they're dished like the l67 then chances are they're the same compression. If so that SHOULD mean they are the same bottom end. I've heard they're all 8.5:1 also.