The truth about horsepower

[John Fitzpatrick]

For what it's worth, this is the plate on my ZF, a fairly early -zero. It's geared a little lower than the Gulf, with 3rd close to 1:1 but I don't know if that's considered "normal". I haven't checked the calculation on what speed it would have allowed a contemporary GT40 to hit...we're pretty sure it came from a F5000 circa 1967. Were those cars pushing the 200 mph envelope with the 289?

John

 

[John]

john i dont no what tyres your running but with say a 295-60-15 those ratios with that diff ratio will give you
59-97-130-150-168 mph at 7000 rpm
cheers Kaspa

 

[Keith]

F5000? Would normally have been a SBC 302 CI. Not saying there weren't 289's but I never came across any.

In 1973/4 we sponsored Alan Jones in a RAM Racing run F5000 powered by a Ford GAA Cosworth V6 so anything's possible!

 

[John Fitzpatrick]

Here's a contemporary photo of the F5000 car Mr. Kitchener told me the engine came out of. The caption calls it a 4.7 Shelby engine. The ZF has the combo speedometer drive/oil pump on the left side.
Didn't mean to divert the thread and I apologize for the drift, CESLAW.

 

[Jim Rosenthal]

More thread drift: I think this is interesting as a lot of GT40s and Cobras have way too much engine in them IMHO. Of course it's owner's choice, but you can scare yourself in a soapbox derby car if you can find a steep enough hill. Maybe a year from now I'll be wishing I had built a more powerful engine, but for now 360hp seems enough, especially with a 4.22:1 final drive ratio.

 

[Doug Clark]

You may not of heard of FactoryPro before as they operate in the Bike world.

If you read this it will tell you their opinion on where modern big hp numbers come from
Following the links on that page to this... read pages 2 and 3 and you can see why all dyno numbers have taken a jump over the last decade or so.