MSO documentation

[PhilS]

I'm trying to figure out the meaning of the horsepower (SAE) rating found on MSOs. My theory is that the rating is max built to spec per cylinder. I noticed on the Daytona Yellow COPO Chevelle at B-J the number was 55. On a Camaro bought by a friend the number is 53.6. This car is supposedly a 375 hp car. I think Zs are 48. Kurt and Daniel have been trying to help but Kurt says an SS350 is something like 51 which might blow the theory. Charley thinks someone has already figured this out but doesn't remember who. I would like to see more MSOs to get a better understanding. The number on a new Vette is around 51. I think a Viper is in the same range. If anyone has an MSO for a 67-69 Camaro I'd appreciate your info or thoughts.

Thanks

[bilede]

53.6 is a 396 but wouldn't tell you which of the 3 versions of that motor it would of been originally.. 325hp, 350hp, or 375hp or even L89 aluminum headed engine.. tach or other clues maybe.. keep looking.

[Chevy454]

We talking about the "taxable hp" rating? Seems like we dug into this many moons ago on this...

[COPO]

We did talk about this several years ago on this board. It is one method to help determine what displacement engine came originally in a car. I have seen a number of discrepancies with solely relying on this method. I found quite a few examples of highly documented BB's with a taxable HP listed as a small block. I think the old thread talked about the formula for this calculation. It is displacement only.

[Chevy454]

Here is the formula...

Diameter squared times number of cylinders divided by 2.5

[PhilS]

Thanks for the help guys but I'm curious about this formula. More than one displacement can have the same bore so I'm not sure how it works. Does the SAE number apply to more than one engine size? Also when I ran through the numbers I wasn't getting a match to the MSOs I've seen. I'm assuming that the number actually has relevance but maybe not.

[Belair62]

Phil my Y Camaro MSO states 53.6

[Mr70]

When I did a VIN search in 1995 on my car,the Missouri DMV sent me pages of 1970 Chevelle VIN's that were numbered around my cars VIN#.(They were pretty loose back then)
I was able to ID a few of the cars to their current owners today.
As was mentioned earlier,there were human errors when reporting these numbers,but they show my L-78 Chevelle as 51 taxable HP,an L-34 Chevelle as 48 taxable HP,and an LS-6 Chevelle as 54 taxable HP.

[mchriscad]

This is very interesting. I have to admit I have never heard about this. I dug out the copy of my MSO on my 67 Vette L89 and it says 57.8. Thoughts?

[PhilS]

Multiplying by 8 would give you 462.4 hp. I think this would be pretty close to correct for a blueprinted engine. Years ago a friend who had held some national records with small block Chevys told me that a blueprinted 302 would make about 380 hp. I think the MSO rating on Zs is 48. That comes to 384 hp. I looked at a bunch of new MSOs at a friends GM dealership recently and the nembers seemed pretty consistent. I'm certainly not sure of anything about this and that is why I'm seeking more info but if it is valid then it might provide another way to document cars without other paperwork. It seems that there might be too many inconsistencies though. More investigation needed. I'd like to see an MSO for an L-72 Vette.