Can someone explain to me in a reasonably simple way how the torque figure is worked out on an engine build. I understand what it is and that it can be measured/calculated on the rolling road but do people actually work it out prior to the build of an engine based on parts they install etc.

I am building a zetec turbo (Silvertop) with Wossner piston etc and looking to run at around 320bhp. I have fitted an ST170 box and looking at clutch options but as the clutches are rated in torque figures i am not sure what a zetec turbo at that BHP will produce. If anyone has any figure they can share it might help me get an idea for what i need but i assume people don't just build these engines any guess the torque figures for the clutches or is it all just experience?

Stay safe.

Adam

 

It depends at what rpm it makes the hp to determine the torque, the lower the rpm the engine makes hp the higher the torque will be

Torque is hp X 5252 divided by rpm

So if you make 320 hp at 4000 rpm

320 X 5252 = 1680640
1680640 /4000 = 420

So your engine is makeing 420lbft at 4000 rpm

But if your engine makes 320 hp at 3000 rpm then your making 560 lbft of torque

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People take factory numbers, and then start dreaming as to how much more theirs might be.

Usually it's all based on fantasy

 

Experience, knowledge and understanding.

 

It depends on the boost profile and engine capacity as the main inputs. But 350lbft would be a ball park figure for your engine.

The 6 speed getrag isn't ideal for your application,the ratios are short and it's weak. Better to for an MTX box if you can.

 

I am already committed to the 6 speed box as i have it, the mounts are fitted and i have some Dave Mac shafts for it. Just need to sort the clutch and diff. The cars been sat for years before i got my head back into building it and the parts were bought a while ago. If i had the option now i would go MTX.