BHP or DIN HP

[Peter Douglas Winn]

Looking at the TRIUMPH TR6 Data Sheet, I saw that the CR series cars had 125bhp at 5000rpm. This suprised me as, to date, I thought they always had a DIN rating. This meant in fact they have more then 125 bhp. Can somebody confirm?

By the way, where is the TR3B?

For the TR5 and 250 Quote "PERFORMANCE DATA Mean Maximum Speed - 109 mph" is this the mean between the 2 top speeds or what? I do not believe that the 5 and the 250 have the same top speed.

If you look further you can find many more mistakes. I think this should be seriously reviewed as it is the first page that potential club members go to.

[Tom Fremont]

What I have seen published is 125 BHP DIN for the later P.I. cars vs. 150 BHP SAE for the earlier ones. Somewhere it is written that the 150 SAE drops to 141 DIN. The TR250 factory manual shows 111 BHP but this I suspect is an SAE value, as no Federal TR6s had as high a rating. Notably torque was published at a higher value for the TR250 than any TR6 carb and even higher than the later TR6 P.I. cars.  Source is the Robert Bentley publication.

 

As for top speed, it was claimed that the TR5  ( with overdrive I believe ) achieved 120 mph for the testers and the TR250 achieved 107 mph for Road & Track in particular, with overdrive, though whether this was in or out at 107 mph isn't given.

 

Note that Kas Kastner prepared the cars for the automotive press, at least in the U.S. One would think that if Kas didn't do it for the U.K. cars someone as skilled probably did.This means cars from the dealers' lots would not likely be able to achieve these values.

 

I'm curious to know what top speed figures this forum's readership get. I've had my TR250 with triple Webers etc. to 115 mph ( drag racing a contemporary Ford Mustang ) but it had more - how much I've been reluctant to see simply for fear of being caught by the highway patrol. ( I'm prone to lose that fear briefly when a drag race presents itself. )

[Peter Douglas Winn]

109.3 mph measured on a track with my USA 1971 TR6. Which is basically the 250 engine and a big wind blockage at the front i.e. TR6 nose design.

[saffrontr]

Peter/Tom, The 125 bhp quoted in the TR6 data sheet for the CR TR6 is a "net" figure and comes from a Triumph publication "Triumph Technical Details" for salesmans use only. The performance figures for the CR series came from the same source as do the CF bhp and performance figures. The brochures also refer to 125 bhp for the CR series and as yet I haven't come across any official Triumph publication for the CP or CR series that refers to either DIN, SAE or gross all of which appear to be quoted in various period and current classic car magazines. The only Triumph publication that I have which quotes anything other than net is 1973 brochure TR731, which quotes a net power output of 106 bhp SAE. Sorry that I can't help with the TR3B or TR5/250 although I will pass your comments on to the respective Registrar's. To recap the figures on the data sheet for the TR6 are all on a like for like basis. I don't know where the 150 gross and 125 DIN commonly quoted for the CP and CR series cars originate from however if you can point me in the direction of a Triumph document that clarifies this the data sheet will be amended accordingly.

Cheers

Derek Graham

[Peter Douglas Winn]

I believe there was a change point in the early seventies when the industry no longer measured HP at the crank output but also took the ancilleries into account. I think this is the difference between BHP and DIN. This explains why a CR car is not much different from a CP car. I presume it was as a result of the German TüV as always!!!!

[jonlar]

Hi Peter and Derek,  I won't quote manufacturer's figures as I'm not that authoritative, but I can tell you from personal experience, that as a Somerset & Bath Constabulary RMP (Road Motor Patrol) officer 1973 - 1977, the earlier Triumph 2.5 PI saloons (either both K-regs, or one a J and the other a K) were significantly faster and torquier than the post '72 cars ever were.   We used to get an absolutely genuine 125mph (each car had 2 calibrated Smiths speedos) below Bath & West Showground (Wraxall Hill) to Lydford without overdrive, whereas the later cars just about made 115 or 120 with the wind behind them, the even later 2.5TC/Ss were total rubbish.   The earlier cars were much freer revving.

[cp25616]

Hi Peter

Yes I too have to agree with Jonlar and Derek in that the TR5 and early PI TR6's (cp cars) were faster and a lot more free reving than the later CR series TR6's.

I know from 24 years of TR6 experience having owned 2 later and 2 earlier TR6's that the difference is very noticable indeed.

The CP cars had a better breathing head with larger inlet valves, completely round inlets on the inlet manifolds allowing more petrol/air mixture into the combustion chambers, plus a  better inlet manifold design over the CR cars, evidently the hairier camshaft, a metering unit that didn't run as lean as the later unit all combine to make the CP cars noticably faster.

I always found the CR cars very short of breath when you approached the 100 mph mark and it took ages to push this figure any further. Not very satisfying really.

If you can Peter get a bog standard CR and a bog standard CP car and just drive the two of them on the same day/route. You WILL get your eyes opened.

Kindest

Alan