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1725 BHP is.... ??

SIVAllan

SIVAllan

Gold Level Sponsor
Does anyone know the actual BHP made by the stock 1725 and the H120 (factory) engines?

Not the "advertised" BHP, nor the "Rootes" BHP, but a figure that is realistic? .. Maybe based on a machine analysis..?

The various books are all over the spectrum, causing one to suspect maybe all of them are incorrect.

Allan
 
alpine_64

alpine_64

Donation Time
JOhn,

You talking power to the wheels or at the flywheel.. in the car or on a bench.

In an alpine i am thinking you are maybe making 75bhp at the wheels.. in the H120.. maybe 90ish
 
SIVAllan

SIVAllan

Gold Level Sponsor
I guess the question is at the wheels. It is not clear in the period articles and books. I have seen H120 bhp stated to be anywhere from 90 to 120, quite a spread. Same goes for the stock 1725, only not so big a spread.

Makes me wonder what is reality... ??

Allan
 
atallamcs

atallamcs

Donation Time
hp

My guess is between 90-100. From other cars I have owned, which is quite a few, it feels like this range is close.

Bill
 
Jim E

Jim E

Donation Time
Put my SV with KB cam, Vizard head mods, 40 DCOEs, Crane HI6 ignition a fairly fresh and balanced engine [1725 20 over] on a dyno think they call them 5.0 dyno. Put down 80 HP at the wheels. The car was crisp and a really nice mover would bark the tires on the two three shift, at 70 on the freeway you mat it and it took off. So either the dyno was off or the stock Alpine 1725 might put 55 HP to the ground on a good day. My guess is the factory numbers were inflated crankshaft HP numbers.
 
SIVAllan

SIVAllan

Gold Level Sponsor
Thanks everyone.

At some point I hope to build a fast (faster anyway) street engine, and this helps a lot with planning (daydreams mainly for now :) ).

Allan
 
RootesRooter

RootesRooter

Donation Time
Gotta remember that the HP numbers they published in those days were theoretical, based on various engine specs. The Tiger's stock 260 was rated at 164 (at the flywheel) in the manuals, but actually only turned out 137 or so. The numbers got more realistic by the early '70s but were probably still optimistic.
 
alpine_64

alpine_64

Donation Time
RootesRooter said:
Gotta remember that the HP numbers they published in those days were theoretical, based on various engine specs. The Tiger's stock 260 was rated at 164 (at the flywheel) in the manuals, but actually only turned out 137 or so. The numbers got more realistic by the early '70s but were probably still optimistic.
Click to expand...

The road tests used to claim 164bhp gross.. and the 136 net, but thats still with an engine on the bench in ideal conditions.. would guess a stock tiger motor in the car with all the hot air to the carb, loss of power in the top loader and the rear end would not be breaking 120 at the wheels. Would be nice to know a DIN figure.. then again many dyno places inflate num,bers so people leave happy.. then there are the different types of dynos that give diffferent results..

Dynos are best used for getting the tunning right on the car.. dont worry about the power readings.. get the car tuned as best as possible and whatever you can put down in the real world will tell you where you are at.:cool: ... but its fun to have the readout anyway :p
 
lemansvk

lemansvk

Donation Time
A mate of mine has Rapier Fastback with 1725 built (for classic racing) by Simon Nuske (spelling?) in Melbourne. Runs twin Dellorto 40s, modified head and cam etc - putting out 110 HP at the rear wheels.

Vic


Jim E said:
Put my SV with KB cam, Vizard head mods, 40 DCOEs, Crane HI6 ignition a fairly fresh and balanced engine [1725 20 over] on a dyno think they call them 5.0 dyno. Put down 80 HP at the wheels. The car was crisp and a really nice mover would bark the tires on the two three shift, at 70 on the freeway you mat it and it took off. So either the dyno was off or the stock Alpine 1725 might put 55 HP to the ground on a good day. My guess is the factory numbers were inflated crankshaft HP numbers.
Click to expand...
 
alpine_64

alpine_64

Donation Time
That will be Simon Noske... and if Simon did the engine.. might be the one with lightweight internals.. or might be one of the other motors.. beyween us.. Simon does lots of motors that may be a little more than 1725cc ..shhhhh
 
V_Mad

V_Mad

Donation Time
I dont think we will ever really know the true BHP output of the Alpine or Tiger engines as the people involved in the process usually have a vested interest in inflating the figures.

Even if we could find a good independant test station, there are too many variables in the system to get a meaningful measurement, and you would also have to decide the exact definition of conditions, ie oil type/grade, details of exhaust system, ignition timing (standard or power optimised?), under bonnet air temperatures etc.

And what about engine prep? How would you obtain a representative set of build tolerances?
 
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