What is the Real Horsepower?

[RAC68]

Hi All,

Has anyone had their Healey’s DYNOed or know for sure what their car’s horsepower actually is? On a recent viewing of Top Gear, a Series 1 XKE and DB5 were featured. It was commented that both manufacturers significantly exaggerated the actual horsepower of their cars and, by today’s measurements, fall within the 100s rather than the mid to high 200s stated.

Although it has always been my opinion that it is the feeling produced when driving my Healey rather than the actual speed (driving 70 MPH feels like I am going well over 100 in my Acura), I have never found that having 150 horsepower (?) in my BJ8 was important. Although most may have slightly modified the operation of their engines in such forms as compression increases, solid state ignitions, hotter coils, etc., the actual horsepower is probably not altered significantly. I would find it interesting to identify a baseline horsepower and the amount of added power (not to mention increases in reliability) some of these modifications do actually contribute.

All the best,
Ray (64BJ8P1)

 

[glemon]

I don't have the answer, but in partial defense of the manufacturers the HP figures quoted in the Healey's day were generally from test of the engine with no acessories, gnerators, water pumps etc. Modern dyno tests of our old cars are usually "rolling road" with not only the engine accessories, but the driveline drag involved. That being said many of the figures were probably exagerated, certainly of interest is that at the quoted power to weight ratios of "our cars" they are significantly slower in acceleration than modern cars of similar power to weight, for example, the first Z3M Roadster was quoted at 240 hp, probably weighed a few hundred pounds more than an early e-type, rated at 265 hp, yet the BMW knocked a couple seconds off the E's 0-60 time.

 

[dougie]

Ray, there's been a number of threads over the years on dyno's. Here's one I remember: https://www.britishcarforum.com/bcforum/u...etup#Post684318
I dyno my 1957 100-SIX MM vintage racer about once a year. The 3 litre motor is built to period race spec.s with three 2" SU HD8's and my car is still street legal. On my last run this year I was close to 190hp at the wheels.

 

[RAC68]

Glemon, thanks for bringing up the changing ways in which HP is/was measured. How does my BJ8’s HP of 148 or 150 (depending on the document referenced) stand against today’s ratings. In reading Dougie’s reference, Andy’s stock BJ8 achieved a 150HP in 3rd @ 5K RPM at the crank which, with an estimated 15% drive line reduction, calculates to 137 HP at the rear wheels. If we use this as a BJ8 baseline, how would the most common mods affect these numbers? What, if any, did my shaving the head .060 to increase compression do to this measurement? Did the addition of a CD and high voltage ignition contribute to the engine’s power measurement? What did I loose by adding a Texas Cooler or did I gain or loose by adding an alternator? Most of all, what was lost to aging and 100+K miles on an un-rebuilt engine?

Only a few, like Dougie, have answers to these real questions for their specific engines. Dougie, your alterations have upped the HP of your racer to 190HP. Do you have an HP for your starting point and a list of the modifications that lead to your overall 190HP?

Ray (64BJ8P1)

 

[Superwrench]

Ray, I've had engines and cars dynoed over the years. Some of them read high and some read low. Every dyno is different. You just have to see what one guys readings are. On a overall estimate, Dougies numbers sound about right on.

 

[glemon]

Here is a good article on the old "gross" vs. "net" hp ratings change in the early 70s, the article states that although many HP ratings were overstated, some of the American musclecars understated the HP for insurance and or liability concerns. I don't think many foreign car manufacturers did the understated HP thing. But it is an interesting read. But as stated hard to know exactly what we had without putting them on a dyno (or at least the car on a rolling road) and test them stock, then with some mods, grassroots motorspots does these kinds of tests, not usually on old Brit Sportscars, but they test carb changes, electronic ignition, exhaust work, head work, etc. etc.

https://ateupwithmotor.com/terms-and-defi...horsepower.html

Road and Track did a test of a Spitfire Motor with dozens of permutations of modifications many years ago (available from the factory competition dept.), I have it if anyone is interested, but that doesn't help us much with the big Healey.

 

[RAC68]

Guys,

Thanks for your responses. I guess I will have to wait for the answers to my questions until my wife wins the lottery and I can spring for the cost of the dyno tests.

Until then, all the best,
Ray (64BJ8P1)

 

[dougie]

Ray, here's another good thread on dyno runs which included the results of some of my first runs. https://www.britishcarforum.com/bcforum/ubbthreads.php/topics/589611/1
BTW, it's about $ 250.00 bucks here in Portland, OR for a few hours on the "rolling road" dyno. Best money you can spend if you're wanting to fine tune your motor for maximum performance. Racing a big Healey I'm always looking to get the most out of the agricultural 6-cylinder.

 

[Legal Bill]

I would not be surprised to learn that the BJ-8 has the advertised horsepower using the old test procedures.

 

[HealeyRick]

Modesty prevents me from participating in this thread

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OK, what the heck: 345 hp dynoed at the crank

 

[HealeyRick]

Here's the results I received from an online RWHP calculator plugging in data from a contemporary BJ8 road test:

 

[elrey]

I just want to thank you all for participating in this discussion. -- elrey

 

[Frankenhealey]

At a recent Healey Drivers dyno shootout here in the UK most of the 3 litre cars were around 130-134 bhp at the wheels. So were the fast road 100-4's

Like Rick modesty also forbids me mentioning my horsepower but hey it's at the bottom of the page

 

[bighealeysource]

Rick and Frankenhealey, you guys crack me up ! Love Rick's youTube video with that lovely sounding V-8 and then he blips the throttle ! Love your Nasty Boys.
Regards,
Mike

PS - come on now Frankenhealey, you have got to put yours on youTube too !!!

 

[Frankenhealey]

Mike,

try these both from the Jersey Festival of Motoring

Moonlight Sprints

Westmount Hillclimb

 

[HealeyRick]

Like Rick modesty also forbids me mentioning my horsepower but hey it's at the bottom of the page

Ian,

Looks like you've got 84 more reasons to be modest than me

 

[Cottontop]

I don't have a U-Tube, but I DO have THIS 10+ year old clip .

I'm embarrassed that I only have a puny (calculated) 300 HP.

Tim

 

[Frankenhealey]

Guys don't feel inadequate! Just remember what we tell the ladies " Size isn't everything "

 

[bighealeysource]

Yeah, but you recall the old saying "there is no substitute for cubic inches or horsepower" or something like that !!!!! Still love the sound of my BN6 straight 6 - at lower rpms sounds a bit like Rick's Nasty Boy until he blips that throttle !
Regards,
Mike

 

[bighealeysource]

Hey Ian,
Just looked at your videos - absolutely beautifully prepared car ! Love the moonlit sprint one although a long time to sit for a short sprint but looked like a ball. How many times did you get to run it, 1/4 mile or what ?
Bloody cool,
Mike