KW and HP

[Anonymous]

Can someone tell me the difference between kilowatts and horsepower, some people talk in kw and others in hp

Thanks Joip

 

[addo]

1HP is about ¾ of a KW. 400HP = 300KW.

 

[Anonymous]

100 horsepower equals very close to 75kilowatts makes for an easy conversion. Some people prefer kilowatts because they cant imagine how all those horses will fit under the bonnet (hood). Personally kilowatts is for powerful floodlights and power tools.

 

[addo]

Either system bears consideration when using power tools. You wouldn't be likely to grab an unfamiliar horse casually with one hand, and attempt to direct it under heavy load, but people think nothing of using a 1HP power saw with little regard for kickback or control. One horsepower can kill you. No need for a GTHO.

 

[Anonymous]

Thanks for sorting that out for me now I'll know how much hp there is when ppls talk in kws, was abit lost there for awhile

Joip

 

[Anonymous]

Kw are best thought of as metric Hp. Just like miles and kilometres, feet and metres, litres and pints. You must be able to convert them in your head or you can only talk to half of the population. I am in the position of growing up in the metric era in a house where pre-metric was the order of the day, so I am pretty good at "converting on the run" so to speak. It can get a bit confusing though.

 

[Anonymous]

Hey guys is there a rule of thumb as to what % you lose in power from flywheel to rear wheels?
Ie 2V 250 is 170HP or 127KW. What would this equate to at rear wheels?

 

[Anonymous]

I am almost certain mine puts out about 124 hp (91kw) to rear wheels at 4000 rpm with an almost stock after market cam. I based this on some 0-100kph times and I spoke with someone at Hume performance who had his 250 2V with 500 Holley dynoed at 124hp to rear with near stock cam.
I believe mine is only up slightly in hp as they came from the factory. 127kw (not rear) although inflated is still probably closer to the truth than a lot of the other factory claims I have seen.
Execute estimated 140hp (gross I think) for a stock 2V based on well publised quarter mile times in a previous post. 155hp for my times only gives me 15 hp gain with all the changes Ive made, elect dizzy, reco, porting exhaust, 500 holley.

 

[Anonymous]

since we're talking about horsepower, i have a 250 in a 3250 lb car and stock it has 98 hp which i think is at the wheel (if not ive got some serious suping up to do ), right now the car goes 0-60 in bout 13 sec. (that was before i hooked up the vac. advance so i dont know what it does now) is that about right? i bought the engine rebuilt from a mechanic and i dont know if its stock or bored out or what, everything is stock on the car, except for the electronic distributor.

 

[xctasy]

Rule 1. One HP is 0.7457 kW

Rule 2: The factory flywheel kilowatt (kW) [called in the trade DIN kW] reading is roughly equal to rear wheel hp in most cases when you have a an automatic. If its a manual, the rear wheel hp will be SLIGHTLY higher than the flywheel kW figure.

Rule 3: The SAE gross HP reading is often 1.28 times the SAE net figure. This is the flywheel figure

Rule 4. For rear wheel drive manuals, rear wheel hp is SAE net, divided by 1.265. For rear wheel drive automatics, rear wheel hp is SAE net, divided by 1.33 for a small C5 or lock-up auto, more like 1.35 less for a C6, FMX etc

Use these figures, and you won't go far wrong. The rear wheel dyno figures are changed by tire and wheel looses which cause a huge difference due to tempratures, and sledom do the dynos have an active calibration which holds up to scrutiny. (I'm not dissing dyno operaters, they are the biggest assest around, but don't think one dynos 300 rear wheel hp is the same as nay others, because it more often isn't.

Altitude, air temp, humidity, tire section, tire pressure and gas type and especially ignition can make massive differences to the final rear wheel hp.

Eg. An early Windsor XR8 Falcon with the Mustang 5.0 V8 has 165 kw (or 228 hp net) with a T5 5-speed gearbox.

This is 175 hp at the rear wheels.

The safest way is to just take the SAE net 98 hp, turn it into Kw, and thats your rear wheel hp.

thetrueslayer 98HP SAE *0.7457= 73 kw, so there should be 73 hp at the bags at the very least.

Just remember, most vehicles never see the factory Hp level unless they have been retuned on a dyno. Follow the four rules, and forget the bull pucky.

 

[Anonymous]

thanks xecute
i have an auto and the 98 hp was the net hp. i guess i do need to supe it up a bit eh?