Old HP vs new HP

Same HP, but the factory was always 'optimistic' in their estimates. In addition, their numbers are measured at the clutch, not the wheels. Typical losses through the drive train are 15-20%.

Based on no data whatsoever, I suspect that a 330 produces somewhere around 220 at the wheels.

Anyone done a wheel dyno run on a 330?

 

The standard changed from gross hp (old)to net hp(new) about 1972 or 73 I think. There is about a 15% difference, gross is with the waterpump, alternator aqnd such disconected. From what I can tell, they also could change the exhaust.

 

Probably not an issue with Ferrari, but some American muscle cars understated HP for insurance reasons. Still measured at the flywheel, but some of the GM big blocks were rated much less than actual.

Though more important, what is the weight and gearing of the car? Even if it isn't 300 HP, it may feel like a 300 HP car compared to heavier undergeared cars. I drove a 400i with a lot of power (over 300 HP advertised), but it is very heavy and felt slow compared to my 328 with less power (260 HP advertised).

 

I agree with all three responses- around 1972 US ratings went to SAE Net ratings ("true" HP), vs. SAE Gross. That would mean 300hp isn't equal to 300hp from 1973 on. But of course to totally confuse things, some muscle cars did understate HP to allow lower insurance rates....hemi comes to mind- rated at 425hp, and probably understated at that!

The only example I can think of off hand is the VW bug 1600 cc motor was rated at 60hp gross, then with no major changes rated the next year at 45hp net. That's a big % change (25%), but typically it seems the difference was lower as a percentage.

 

Very true indeed.

I owned a 69 Boss 302 rated at 300hp, but everyone knew that was a joke.
There was an arbitrary cutoff by the insurance companies of 300hp - anything above that was labeled a high performance car - watch your insurance triple!

BTW, that car could smoke my modified TR in the real American world of straight line acceleration...

 

Faster then the testarossa- from a 302 cu in V-8? That must have been something....I know the earlier GT350 shelby (1965?), rated at 306hp tested at 0-60 in 6.5 seconds, 1/4 mile 14.9- slower than a testarossa- I thought the older GT350's were faster then the 1969 shelby's and therefore the 302's from '69? Did you have it modified?

My 300hp (net HP) STS with automatic did about 6.8 0-60 and weighed almost 4,000 lbs...somthing seems off

 

Remember that all dyno testing lacks in one very important area. Sure it is nice to see that speedo cranked out and the tach at redline but remember one VERY important thing -- airflow. Just because the speedo reads 160MPH --- is there actually 160 MPH of AIR going over your hood? How much airflow is going into your rad? This is why teams with gobs of money use wind tunnels - to simulate the airflow that goes around the entire car. I had some dyno runs done on my street car. The manufacturer claimed 425 HP, I only seen 337 at the rear wheels, so I allowed 15% drivetrain loss. I went to another dynoshop and they had a huge fan that was placed infront of the car to blow air onto the rad and over the hood. Same temperature 70 degrees F. Now the dyno showed 397 hp. Magically 60 HP came back. So remember that when you are "bar racing" your horsepower claims.

 

Well faster.

First, despite it being 12 cylinders dual this and that, it's still only the same size engine. IMO, you would have to mod it a bit to get it good times in the 1/4, but it runs pretty hard after 80 - 100 or so. Given the weaker trans on my TR, I would not even think of it.

The GT350 was a shelby in name only - It had very little in common with anything made by Carroll Shelby - and it was a dog.

I never even noticed a 69 shelby - by then they were a joke, but the Boss was a completely different engine, trans, suspension, and body, and was well underated. The Boss 429 was a dog on the street, but not bad on the track.

With a few tweaks via 3rd party speed equipment, it opened up nicely.
I tossed in a different aluminum intake, headers, rear, and some other toys to run strong 13s at Maple Grove without blowing things up ...

 

You guys are comparing apples to oranges.

There's SAE net and SAE gross, the figures which were used to measure American cars of the time. As Mark Eberhardt and Andrew911 point out, the difference came in 1972, and was marked by measuring horsepower without ancilliary parts (gross) or with (net).

However, Ferrari engines (particularly the 330) had horsepower measured in DIN European numbers, which were very close to the lower SAE net figures.

Ferraris were never measured in SAE gross figures, although they may be a bit "optimistic".

--Matt