Hi group,

In response to a request for rear wheel horsepower by HK1837, I think it suitable to put a few myths to rest in regard to power output quoted as opposed to that computed by the PS calc.

In October 1969, I had my car dyno tuned at Perfectune by Dave Bennett. This was after I had a recall by Southern Motors to upgrade it to Bathurst specification. The car got a new air cleaner with four large openings in it. I was asked at the time if I wanted a cylinder head exchange but as this was to be done at my expense I told them to take a hike. My car always went well and when racing my mate in his GT I always won. At Perfectune, the car was measured with 245 horsepower at the rear wheels, an amazing statistic to say the least. All they really checked was the ignition timing and the carburettor and in reality did nothing to the car. When I told my mate, he immediately went in his GT to see what it had. They measured 224 horsepower after a little fiddling. We did not believe that the readings were correct as on the PS calc the cars would have been doing a much higher speed through the traps. After some research and the question posed to Bob Jane it turns out that Perfectune had calibrated their machine to reflect the engine horsepower. When this was done, all was fine with the PS calc and the time slips from the strip. My GTS 350 was a real good one to quote Bob Jane but he also added that their pre-delivery on GTS 350s was second to none at the time. I can recall Max Stahl in Racing Car doing a dyno test on a race GTS 327 and getting 150 horsepower at the rear wheels so all seemed fine with that result on the PS calc.

The GTS 350 engine was rated at 300 horsepower so to get 245 was pretty good I thought given the 300 figure was an SAE inflated one. My car used to spin the tyres into third gear on the Aquajets it came with and would run 14 seconds all day if you wanted to.

The question begs as to how much horsepower quoted is fact and how much is the guy pulling you leg because thats the figure you wanted to see or hear?

Mike.

Mike,

Awesome information and personal experience here. Many thanks for sharing this with us. I am aware that Peter Robinson tested an XW GT in his magazine in 1969 and they got 222 horsepower at Dave Bennett's place. As an aside, Holden brought to an

not sure if this is relevant but my 355 holden made 460 uncorrected on COME's engine dyno and shows 430 by the slide rule (117mph)

Once tuned to the car id expect to get it a little closer, remembering that no dyno can simulate the effect of drag/aerod

i would guess mike that your heads are 041,s. i have spoken to a few original owners of t&g and they changed to 186 fuellies, only to find out later the o41 was the better casting, and 1.94 intakes worked better as a streeter. i have a pair of 041 heads b

A modern chassis dyno sure can simulate the effects of drag/aerodynamics. A power/speed calculator is always correct as you cannot change the laws of physics.

All,

An interesting addition here is for the VZ CV8Z Monaro. A run-in example with an air box modification and a some other minor add-ons (not exhaust) produced 235 rear wheel horsepower on the same dyno as the HT GTS 350 Monaros mentioned previously.

Edited by user Monday, 6 October 2008 7:31:30 AM(UTC)  | Reason: Not specified