Seven America on the Rolling Road at Lotus Engineering at Ann Arbor, Michigan

Two: Anybody's Guess


Now the Seven that I, or I should say, my wife owns(!) is a Seven America, which means it has a 948cc Austin Healey Sprite engine in it. It does have twin SU H1 carbs (read: small ones) but even the published power output for the engine in prime condition is a mere 43 horsepower. Granted, it's pushing less than 1,000 pounds around, so the car is without a doubt quick and fun, but plenty of Sevens have far more horsepower on tap. So with just a bit of hesitation, I went ahead and volunteered (I do that too much these days!) Apparently only one other Seven owner was interested, but as I was the first to volunteer, I was the 'lucky' one...

photo: 948cc BMC 'A' Series engine:
period published horsepower - 43

Thinking I'd have a bit of fun while waiting for the day to arrive, I posted messages to a couple of Lotus and Vintage Race email lists asking for subscribers to have a guess at the output of the little engine in my Seven. I had 19 repondents, several of whom own Sevens themselves, and several who obviously don't! Some of the guess were humorous, while others were actually pretty close. Here's what they were in no particular order:

  • 37 BHP at the wheels.
  • I'll take a stab at 37 HP at the rear wheels at around 5300 RPM in whatever gear you happen to be in.
  • My guess, 31bhp at the rear wheels.
  • At the wheels? Probably about 40 bhp?
  • I'll put my money on 32bhp at the wheels.
  • My guess is that they will run your 7 in third gear on the dyno and the figures will be around the 39.6 BHP at around 5400 rpm. at the wheels Losses are usually around the 25-30% mark on a chassis dyno vs. an engine dyno.
  • at-the-wheels estimate - I'll say BHP = 54
  • My guess is 61 HP.
  • The stock 43
  • 12 ;o)
  • 62 at the wheels!
  • 69
  • 56 hp
  • 36 BHP at the wheels
  • 28
  • At the rear wheels I'm guessing 28.7
  • I guess 52 bhp.
  • Knowing that you are always running at the highest state of tune, my guess is 49 BHP @3,500 rpm.
  • I would guess 40hp at the rear wheels.

So we obviously had a pretty good range of guesses, some more optimistic than others. The range was from 12 to 69 bhp, with most of the guesses in the area of 30 to 40 bhp. Read on to see who was right!


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