Thread: ENGINE TRANSPLANT???

Originally Posted by Dougal

Which beat all the works teams and privateers with purpose built big power V8's.
Unlimited class, diesels win.
Hmm.

The reality is, you can't use big hp offroad, anyone who thinks you can hasn't thought about it particularly hard.
You can use big torque though and the lower that torque is in the rpm band, the better.

Lets do the maths.
2.5t 4wd.
Grip on the ground of 0.3 times it's weight.
Power required to spin all four wheels at 50km/h.
P = force x velocity
P = 2500(kg)*9.81(g)*0.3(grip)*13.9 (m/s)
P = 102kW.

What is the aim again?
Going places?
Throwing mud/sand?
Bragging around the camp-fire?

BS, build both, drive both, then tell me your personal experiences

Each has their own purpose to fulfill........

None of us are racing the Dakar, so really, pretty irrelevant, engineers talk theory, some of us, use pragmatic thought process, others, do it cause they wan't to

Can you use big HP offroad?.........must be no, that's why my next non paying personal project invlolves a shade under 500ci of engine

Am I a ******? well I'm only a male human

Do I need to brag around the camp fire? I think not

You need the big power for throttle response and acceleration and for speed.

Originally Posted by Brian Hjelm

You need the big power for throttle response and acceleration and for speed.

No, that's what big torque provides.
Big power only arrives with high revs.

The two are often confused.
If Rovercare is building a 500ci vehicle then he's probably looking for big torque. As many smaller motors easily provide far more peak power. Skyline or ford turbo 6's for example.

Originally Posted by Dougal

The two are often confused.
If Rovercare is building a 500ci vehicle then he's probably looking for big torque. As many smaller motors easily provide far more peak power. Skyline or ford turbo 6's for example.

No I'm after both, Torque and HP, My 4BD1 is quite pleasant to putt around in, but stand on it

Originally Posted by Dougal

No, that's what big torque provides.
Big power only arrives with high revs.

The two are often confused.
If Rovercare is building a 500ci vehicle then he's probably looking for big torque. As many smaller motors easily provide far more peak power. Skyline or ford turbo 6's for example.

People often confuse torque and horsepower. Torque is capacity to do work. Horsepower introduces a time factor, work done in time taken.

I can assure you that if you don't have horsepower you don't get high speeds even if you have sufficient torque to move Ayers Rock from a standing start. Ask any knowledgable truck operator.

Many, if not most, of those small high revving blown engines are all revs and noise and could not pull a greasy stick out of a dog's bum from a standstill. Revs, boost, and low gearing are how they function. If you want capacity to work you need cubic inches whether they are blown or not.

You can design and build an engine for one extreme or the other. You will be disappointed with its servicability outside its design parameter. A genral purpose engine that has reasonable performance at both ends of the revs scale will be a compromise.

Originally Posted by rovercare

Am I a ******?

Oh i can answer that one











and i bet you can to

Originally Posted by Vern

Oh i can answer that one

and i bet you can to

Jeez............ you know yer mates in this world.

Originally Posted by Brian Hjelm

People often confuse torque and horsepower. Torque is capacity to do work. Horsepower introduces a time factor, work done in time taken.

Torque is simply twisting force. More of it means you accelerate harder, pull higher gears etc.
Power can be expressed several different ways to make it clearer.
Power is force x velocity.
Power is torque x rotating speed.
Power is how fast you are performing work.

Originally Posted by Brian Hjelm

I can assure you that if you don't have horsepower you don't get high speeds even if you have sufficient torque to move Ayers Rock from a standing start. Ask any knowledgable truck operator.

"don't have horsepower" means what?
Any turning shaft has power, presume you're talking about how much.
Higher peak power is shown in two ways.
1. Higher top speed (provided the right gearing is used).
2. You can get up hills faster. Providing that power was your previous limiting factor. In most cases offroad it's not.

Originally Posted by Brian Hjelm

Many, if not most, of those small high revving blown engines are all revs and noise and could not pull a greasy stick out of a dog's bum from a standstill. Revs, boost, and low gearing are how they function. If you want capacity to work you need cubic inches whether they are blown or not.

You can design and build an engine for one extreme or the other. You will be disappointed with its servicability outside its design parameter. A genral purpose engine that has reasonable performance at both ends of the revs scale will be a compromise.

That's true of any engine, whether it's a smaller engine with forced induction or, a big 6 or a V8.

Many people in the quest for "more power" build engines to provide their peak torque higher up the rev range. The closer your peak torque gets to your max rpm then the more power you make.
And the more your engine sucks for drivability. Some can't even idle.
Which is why choosing an engine for offroad based on peak power is just dumb.

The goal for any offroad engine is maximum area under the curves, not highest peak. To get maximum area under the curve you need lots of torque at low rpm.
This is what diesels do and funnily enough why people loved the old V8's as well. The peak power from some older V8's was woeful, holden had a V8 in the mid 90's which produced 3kw more than their V6.
But people still preferred the V8.