Chevy454
04-22-2001, 03:17 AM
Well, as I was looking thru some AMA specs for the '69 cars, I ran across something that rattled my memory of a thread on the old message board a year or so ago. What I found was a formula for "Taxable Horsepower", which is listed on the MSO's and also on some titles.
Diameter squared times number of cylinders divided by 2.5
Here is a copy of the original thread:
What is the taxable HP number shown on the title or MSO of yenkos and other COPO's?? Are they coded as 396er's = 53.6 or as 427's = 57.8 or as small blocks 51.2?? Please post your numbers. - COPO
Being the original owner a Dick Harrell 427 Nova, I took a look at the original title, which calls for 51hp. The car was originally a 396-375 car before the Harrell transplant. This is titled in Missouri. Could each state have a different way of rating taxable horsepower? I believe this could be the case? - Ray Morrison
Article:
I own a Gibb-Harrell 1968 427 Nova. I also have the MSO dated
7-19-68. The H.P. (SAE) 48.0. This is an Illinois MSO from Fred Gibb. - Kim Howie
COPO:
I saw your posts on Team Chevelle and Team Camaro about "taxable horsepower", and you gave a very good explantaion(sp?) of it. How about posting it here so everyone can understand it better?
On our titles, they all show "51" under horsepower, but we don't have the original titles or the original MSOs for them, either, which is what will be needed to help figure this out. Here in "the middle of nowhere" Missouri, you can pretty much put whatever you want on this portion of the title.
The problem is that there aren't too many owners like Ray who still own a supercar that they purchased new back in the "hay day", so this may be a next to impossible task! But, it could prove to be valuable information. - Yenko Sportscar Club
The taxable horsepower figure was always listed on the Manufacturer's Statement of Origin (MSO) This is the form sent from the assembly plant to the dealer to use for at the state level when applying for the original title. It is calculated by squaring the bore's diameter, multiplying by # of cylinders, then dividing by 2.5. A 307 would be 48.0, a 302, 327, 350 would be 51.2, a 396 would be 53.6, a 402 would be 54.5, and a 427, 454 would be 57.8 In some states, at least MO and IL, this number was also on the title even through successive owners. Sometimes it is shown under the heading HP/CCM. Be aware that there are completely documented cars with the incorrect taxable hp number on the MSO, so don't worry if yours is wrong. While it's possible mistakes worked both ways, this is potentially a method (not foolproof) of determing original engine size for your car if you have no other documents and the original engine is gone. I'm trying to get a larger sample size to get an idea of how often it was correct or incorrect and am also curious what is listed for COPO's. - Anonymous
Thanks for a good explanation of the taxable horsepower figures on the MSO's.
The HP rating on the '70 Yenko Nova MSO is 51.2, however we have only found one car that has it's MSO.
I have found on the MO title searches that some of '70 Yenko Nova's were originally titled with a HP rating of 48.0. If I locate additional '70 Yenko MSO's I will relay the info for your research. - Marlin R. Spotts Jr.
I have the original title to my car which is Yenko inventory car #9625 and the horsepower # is 53.6. I found your explanation very helpful and interesting, especially the fact that these numbers were not always correct. - Jim Hughes
ps. I didn't notice until after I had it typed up that the formula was given in the original thread, but I thought this still might be of some interest to some of you.
Diameter squared times number of cylinders divided by 2.5
Here is a copy of the original thread:
What is the taxable HP number shown on the title or MSO of yenkos and other COPO's?? Are they coded as 396er's = 53.6 or as 427's = 57.8 or as small blocks 51.2?? Please post your numbers. - COPO
Being the original owner a Dick Harrell 427 Nova, I took a look at the original title, which calls for 51hp. The car was originally a 396-375 car before the Harrell transplant. This is titled in Missouri. Could each state have a different way of rating taxable horsepower? I believe this could be the case? - Ray Morrison
Article:
I own a Gibb-Harrell 1968 427 Nova. I also have the MSO dated
7-19-68. The H.P. (SAE) 48.0. This is an Illinois MSO from Fred Gibb. - Kim Howie
COPO:
I saw your posts on Team Chevelle and Team Camaro about "taxable horsepower", and you gave a very good explantaion(sp?) of it. How about posting it here so everyone can understand it better?
On our titles, they all show "51" under horsepower, but we don't have the original titles or the original MSOs for them, either, which is what will be needed to help figure this out. Here in "the middle of nowhere" Missouri, you can pretty much put whatever you want on this portion of the title.
The problem is that there aren't too many owners like Ray who still own a supercar that they purchased new back in the "hay day", so this may be a next to impossible task! But, it could prove to be valuable information. - Yenko Sportscar Club
The taxable horsepower figure was always listed on the Manufacturer's Statement of Origin (MSO) This is the form sent from the assembly plant to the dealer to use for at the state level when applying for the original title. It is calculated by squaring the bore's diameter, multiplying by # of cylinders, then dividing by 2.5. A 307 would be 48.0, a 302, 327, 350 would be 51.2, a 396 would be 53.6, a 402 would be 54.5, and a 427, 454 would be 57.8 In some states, at least MO and IL, this number was also on the title even through successive owners. Sometimes it is shown under the heading HP/CCM. Be aware that there are completely documented cars with the incorrect taxable hp number on the MSO, so don't worry if yours is wrong. While it's possible mistakes worked both ways, this is potentially a method (not foolproof) of determing original engine size for your car if you have no other documents and the original engine is gone. I'm trying to get a larger sample size to get an idea of how often it was correct or incorrect and am also curious what is listed for COPO's. - Anonymous
Thanks for a good explanation of the taxable horsepower figures on the MSO's.
The HP rating on the '70 Yenko Nova MSO is 51.2, however we have only found one car that has it's MSO.
I have found on the MO title searches that some of '70 Yenko Nova's were originally titled with a HP rating of 48.0. If I locate additional '70 Yenko MSO's I will relay the info for your research. - Marlin R. Spotts Jr.
I have the original title to my car which is Yenko inventory car #9625 and the horsepower # is 53.6. I found your explanation very helpful and interesting, especially the fact that these numbers were not always correct. - Jim Hughes
ps. I didn't notice until after I had it typed up that the formula was given in the original thread, but I thought this still might be of some interest to some of you.