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1275cc HP and torque figures

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saabmp3

saabmp3

Jedi Hopeful
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So a couple of weeks ago regularman was asking about throwing a turbo onto a 1275 engine and the topic of HP came up. We all piped in about how the standard 1275cc put out 65 HP, except for Jack (who said something around 40).

Well, if any of you look at your Moss catalog (which I found in my mail box today), the back of it has an ad for a supercharger kit they're trying to sell (for 2995!). Right next to it is a dyno graph showing the stock 1275cc putting out a peak of 43HP. Jack, maybe this is where you got that number from? I just thought of this when I saw the graph.

On a side note, that supercharger says a max of 67HP (rear wheels). I'm a little disappointed by that number.... Does that seem right?

Ben
 
The official AH factory rating for the 948cc is 43 HP at 5500 RPM. I suspect they just got something mixed up in the graph--that kind of thing happens all the time in publishing. The technical info gets passed from the people who understand it to the folks who lay out the pages, who get something backwards, then somehow it doesn't get checked, because the people who should check it are busy with an emergency, and.....
 
That must be 65 hp without other mods. There are guys that run up to about 130hp in their race set-ups.
 
When 1275 were originally built, the "standards" for measuring horsepower was more lax than they are today.

So comparing the orginal 65 HP number to today's numbers is like "comparing apples and oranges"

Typically, in the old day, all parasitic drag (including the water pump) was removed and the engine was placed directly on an engine-dyno (not going through the trans and diff). And many times, an engine that was built to the best tolerances was selected for this test. This resulted in pretty optimistic numbers.

In the 80s, car companies began testing in a more realistic manner (but still on an engine-dyno and not through the drive wheels). Engine horsepower values dropped partly for this reason (but also due to emissions requirements).

The recent Moss number are from a rear-wheel dyno.
This means the engine must also churn the trans and differential gears, resulting in a measurable loss of energy.
This is sort of a guess on my part but I'd say that a 1275 engine looses about 15% of its horsepower through the Spridget drivetrain. In other words, a 1275 with the Moss supercharger kit (which makes around 67 HP at the back wheels) will make about 80 HP "at the crank".
A truly stock 1275 engine from "the good old days" probably made no more than about 50 HP at the back wheels.
A well-used 1275 might make down around 45 HP (maybe this is where the Moss numbers come from?)
Hard to guess what a stock 948 Frog made at the rear wheels, but likely not more than 34 HP or so.

By the way, the HP losses that were caused by the "new" emissions rules of the 80s have been resolved.
I.E.~Honda's recent S2000 sports car makes 240 (SAE rating) from less than 120 cubic inches (2000 cc) and passes the tougher "LEV" (low emission vehicle) standards to boot! Also, many modern cars have fwd transaxles. These tend to "waste" less energy, so there is some increase in power at the wheels due to reduced parasitic drag. The newer 5W-20 engine oils don't hurt either.
 
Moss #'s for their SC are conservative and they were taken from a stock engine that had never been rebuilt. However, dyno numbers are pretty useless if they come from different dyno machines. I can gain 10 HP by driving 10 minutes to another shop to use their dyno. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif
 
Outstainding Trevor, use the one with the bigger figures before you go to the track. Any given advantage.


For some reason I have always thought a 948 engine was 42 HP as claimed by the Healey boys. Assumes a well tuned engine in good condition.

42 Stock
10 Special head
2 carbs
2 1275 exhaust
5 cam
9 .60 over
----
70 HP

Above just a guestimate on my part useing the usual sources. However, those things all together make a significant percentate improvement with out a lot of bucks. Think I am too generous, ok cut all in half, now you have 58 HP still a big jump.
 
How many horses do you think this guy is reining in? /bcforum/images/%%GRAEMLIN_URL%%/grin.gif /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

https://www.youtube.com/watch?v=bz2OB0mwWBw

PS: When this is over, at the end, check out the video with Dutch Mandel testing the Caterham 7!! /bcforum/images/%%GRAEMLIN_URL%%/lol.gif
 
MG Metro Turbo has a published output of 93bhp. That's on an A+ motor if I remember correctly. Not really sure what the difference is between the Midget A and the A+ motor.
 
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