Cheers Rob, have you seen the youtube video of Kyle Dunkles 8000 lb Peterbuilt running a low 14 second quarter? Oh yes, he smoked a 240 BHP 2000lb Mustang at the time. Pete was giving 1000BHP but most important was the 3000+ ft/lbs of TORQUE! 8 wheels driving and he did mega burnouts, that's TORQUE for you!

When you tighten a whel nut up you do so to a given TORQUE figure, 100N/m for example. This equates to a FORCE of 100 Newtons being applied perpendicular to the radius from the centre of the turning circle at a distance of 1 metre from that centre. How much power is exerted?

Power is a measure of work done, or the ability to do work in a given time. BHP figures are a mathematical result of torque produced multiplied by engine speed and usually divided by a constant.

200ft/lbs of torque at 2K rpm will be more use in a road car than 1000BHP at 18K rpm and will accelerate that same car much quicker.

D.

Wouldn't go round corners too quick would it !
If you have ever driven an artic unit on its own in the wet you will understand.

Fair comment but I think this is splitting into two different debates. Which is better good torque from low down and spread over a wide rpm range or high revving peaky motor giving high peak BHP figures but little torque till its revving its nuts out is one subject, (as I said in my original reply a lot depends on what you intend to do with the car) the effect of a heavy engine on handling is another.

Having said that a heavy motor doesn't necessarily mean understeer if its placed well back in the engine bay (my original point). Point taken about driving a tractor unit on its own in the wet, been there played that game, fun it isn't. But have you ever seen truck racing? Those boys corner at speeds you'd think impossible in rigs weighing in at 7 Tonnes plus. Yes if a heavy motor is placed up front over the front axle for example a la Audi then understeer is almost guaranteed but move that weight back in the chassis to get as near to 50/50 weight distribution and any understeer will be caused by the steering/suspension geometry not the weight.

hopefully I've cleared up my points now?

D.

Clear as Dave, and points taken and agreed especially about understeer and VAG products (I have two 90 Quattros and they are a handfull in the wrong hands in the wet as I found out)getting the balance will be the making of a car,the one I built for Teamtrain has a lot of oversteer and the engine and rad etc are as far back as poss.

Friend of mine in California has a Chrysler 300 whatever in an estate version with a Hemi fitted to it SRT and upgraded box etc etc etc and it is quicker than many bikes from a standing start all down to torque,but it does weigh as much as a small house.

big engine debate
 

my haynes has a mildly tuned alfa v6 3.0,so i feel able to coment,there is ample power so much that the low gears wheelspin makes it difficult to use,at santa pod my best quarter i set of in third to avoid wheelspin,it has been properly cornerweighted and has good even weight distribution total weight 690 kg,i think it has a bit to much power .i thought i needed 200 bhp (too much)and this was much cheaper than trying to tune /install duratec,if i was building another i would go for a zetec with suitable mods about 165 bhp,or even bike power.It still sounds nice with pipes each side,one more point these are made for ourselves and any choice is good if thats what you want...

In my case I went with a 60 degree V6, that fit very nicely.
I am not sure if the engine is available over there, but it is a GM 3.4L.
It weighs very close to the Miata motor and produces around 200 hp in the trim I have it in.

Al

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Yep too much power cant be used, understeer,oversteer and horrendous wheelspin , totally undriveable. Its all a load of Bull just build and enjoy , all problems can be sorted when finished.

http://www.youtube.com/watch?v=6oRam...eature=related

And he`s not even giving it the beans.

Bob

I think too many people focus on horsepower and don't focus on the rest of the suspension and components that will make the 200 horsepower work.
Build the whole car to support 200 horsepower or whatever power you want, don't just throw a 2 or 300 hp engine in a 145 horsepower chassis and then expect to have a car that hookups when you dump the clutch.

When I built my chassis I built it to take the power of a small V8 if I should ever wish to install one later.
As time goes on though I find the 200 or so I have is just the right amount for what I use the car for, it works for me, but doesn't mean it works for anyone else.

Like Bob mentioned, build the car the way you want and enjoy it, the power is irrelevant, having a good time is relevant.



Al

To quote Colin Chapman, on whose lotus 7 our cars attempt to emulate, for increased speed just add lightness.
The lighter it is the better it will handle which means it should go round corners as well as just going quick in a straight line. A 100hp car that weighs half a tonne will be quicker than a 200hp car that weighs a tonne.

Nose heavy cars don't handle - Fact!

It's about power to weight not outright power. If you've power you can't use then its wasted.
My GTM libra has a 160vvc K series engine and to be honest it has too much torque and is not nearly as much fun to drive as my old MX5 was.
The caterham that went round the top gear track is nearly the fastest car they ever had there but by no means the most powerful!

surely the two cars would be the same, as they would have an identical power to weight ratio?????