TR4/4A History of the Triumph TR4 and the Surrey Top

Found some information about the Surrey Top.
https://en.wikipedia.org/wiki/Triumph_TR4

Some mis-information there...48 spoke wire wheels...some cars fitted with vane type superchargers producing 200 bhp at the flywheel...a few others...

But the surrey top thing was pretty unique to the TR4...I believe that the Lotus Elise has something similar...at least a soft, portable center section for enclosing the cockpit.

martx-5 said:

bhp at the flywheel

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I think thats a typo... BHP = Brake Horse Power, The "Brake" is also the name for a Dyno... or "To the Wheels". Can't have the same HP at the flywheel and at the wheels. Pretty sure that whoever entered that info just meant HP.

martx-5 said:

Some mis-information there...48 spoke wire wheels...

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Both 48- and 60-spoke wheels are listed in the 1st edition of the TR4 Spare Parts Catalogue, each available in bright chrome, dull chrome, alum. finish or lacquer finish. How many might have been delivered with any of the above, I don't know. But that's where the informatin came from -- straight from Triumph!

pjsmetana said:

martx-5 said:

bhp at the flywheel

Click to expand...

I think thats a typo... BHP = Brake Horse Power, The "Brake" is also the name for a Dyno... or "To the Wheels". Can't have the same HP at the flywheel and at the wheels. Pretty sure that whoever entered that info just meant HP.

Click to expand...

Actually, the BHP is generally the tern used for flywheel horsepower. The "brake" is a dynamometer (dyno for short) that has an input shaft into the flywheel just like a transmission would and is often referred to as an "engine dyno", the dyno that measures hp at the wheels is referred to as a chassis dyno and is more often referred to as WHP (wheel horse power).

WHP is seeing more common usage, especially in the tuner world, while most manufacturers still use BHP with numbers generated from test engines pulled from the assembly line. The test engines used to be run with the fewest accessories possible, including an unmuffled exhaust, to boost the numbers. Now, most manufacturers, use a test engine with all of the "standard" accessories installed to generate their advertised BHP.

swift6 said:

Now, most manufacturers, use a test engine with all of the "standard" accessories installed to generate their advertised BHP.

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Hmm, I thought that was called "SAE net" (or DIN or ECE).

Anyway, I agree that "brake" hp has nothing to do with the brakes on the car, but rather a dynamometer.

However, I'm not convinced that 200 bhp is impossible, given a moderate amount of boost and a few other modifications. There are apparently folks making that much today (at the flywheel) without the boost!

OK, so there was 48 spoke wheels available...Im' not discounting the fact that 200 HP isn't possible, but from reading the text, one gets the impression that Triumph supplied cars with superchargers...as "some cars were fitted with vane type superchargers"...

We know the Judson was available in the aftermarket, but did Triumph offer them or not??

TR3driver said:

swift6 said:

Now, most manufacturers, use a test engine with all of the "standard" accessories installed to generate their advertised BHP.

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Hmm, I thought that was called "SAE net" (or DIN or ECE).

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It was called SAE, then DIN etc... But I believe that referred more to the standards used for the measurement. For instance, I had read that SAE testing was with zero accessories, unmuffled exhaust etc... and that DIN began to include the standard equipment accessories and a production exhaust etc... to more accurately match what would be typically available in the car. Publications, from what I remember, referred to it as BHP most of the time regardless of SAE or DIN. I've also seen the powered generated compared in Kilowatts and Newton Meters. Regardless, BHP, SAE, DIN etc... were all measured directly at the engine output, not at the wheels.

TR3driver said:

swift6 said:

Now, most manujavascript:%20void(0)facturers, use a test engine with all of the "standard" accessories installed to generate their advertised BHP.

Click to expand...

Hmm, I thought that was called "SAE net" (or DIN or ECE).

Anyway, I agree that "brake" hp has nothing to do with the brakes on the car, but rather a dynamometer.

However, I'm not convinced that 200 bhp is impossible, given a moderate amount of boost and a few other modifications. There are apparently folks making that much today (at the flywheel) without the boost!

Click to expand...

Actually BHP is derived from the Prony Brake developed by <span style="font-weight: bold">Gaspard de Prony</span> to measure the torque produced by an engine. The term brake horsepower is one measurement of torque derived from this method of measurement.
go here for a description and photo of a Prony brake

martx-5 said:

We know the Judson was available in the aftermarket, but did Triumph offer them or not??

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Kind of depends on what you mean by "Triumph". I believe you could buy them from some Triumph dealers with the Judson installed even though the factory disavowed all knowledge. Cal Sales in particular modified a lot of cars in various ways; they'd do anything to make a sale!

angelfj said:

Actually BHP is derived from the Prony Brake developed by <span style="font-weight: bold">Gaspard de Prony</span> to measure the torque produced by an engine. The term brake horsepower is one measurement of torque derived from this method of measurement.

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Your correct, especially in the sense that all dynamometers measure torque, the HP is then calculated based on the torque and rpm.