Thread: Busmans 82 Rangie with Isuzu 4BE1

I am going to give this a go for something different.
Everything is there ready for installation, just need to work out ratio etc.
Probably 15-17 psi would be the go.

Originally Posted by Busman

I am going to give this a go for something different.
Everything is there ready for installation, just need to work out ratio etc.
Probably 15-17 psi would be the go.

When you are doing your calcs, remember that you will get a few psi in thermal and friction losses between the SC and the intake.

Here are the results of the calcs I did for the Toyota 15B engine (4 litres) that was going to have a SC14 fitted. I don't know if it happened. The 60% efficiency was plucked from thin air, let me know if you can find a compressor map for an SC14.

At 3000rpm engine and 6720rpm supercharger you are forcing 6720x1.4 litres of air into 3000x2 litres of space.
This is forcing in 1.57 times the air volume, which can deliver aroundn 50% more torque than NA.

Due to the heating of air when compressed, the actual boost read will be around 18psi. This is based on the compressor being 60% efficient.

If you intercool the charge and remove 60% of the heat, the air volume will be the same but you'll drop to around 11psi of measured boost and your EGT's will be lower. The intercooler won't change the temperature of the supercharger, but it will lower the pressure it needs to pump against.

At 2000rpm an intercooled supercharger delivering 12psi will require around 14kw of shaft power to run. At 3000rpm it will require around 22kw and this power is taken straight off the crank.
With no intercooler that would be 21 and 31kw of power.

Originally Posted by Dougal

Here are the results of the calcs I did for the Toyota 15B engine (4 litres) that was going to have a SC14 fitted. I don't know if it happened. The 60% efficiency was plucked from thin air, let me know if you can find a compressor map for an SC14.

At 3000rpm engine and 6720rpm supercharger you are forcing 6720x1.4 litres of air into 3000x2 litres of space.
This is forcing in 1.57 times the air volume, which can deliver aroundn 50% more torque than NA.

Due to the heating of air when compressed, the actual boost read will be around 18psi. This is based on the compressor being 60% efficient.

If you intercool the charge and remove 60% of the heat, the air volume will be the same but you'll drop to around 11psi of measured boost and your EGT's will be lower. The intercooler won't change the temperature of the supercharger, but it will lower the pressure it needs to pump against.

At 2000rpm an intercooled supercharger delivering 12psi will require around 14kw of shaft power to run. At 3000rpm it will require around 22kw and this power is taken straight off the crank.
With no intercooler that would be 21 and 31kw of power.

So - best case scenario, maximum output for a 4BE1 would increase from [edit - see corrected calcs below]

Excellent info guys, and provides a good description.

Originally Posted by isuzurover

So - best case scenario, maximum output for a 4BE1 would increase from ~110HP at the flywheel to ~170HP ???

74kw stock, force 57% more air in and you get around 116kw.
But 22 of those kw are needed to drive the supercharger, leaving a total of 94kw or 127hp.

I'm thinking these superchargers only really worked on petrols because the fuel evaporation did a lot of extra cooling for them.

12psi intercooled on a turbo would give you about 120kw or over 160hp.

Originally Posted by Dougal

74kw stock, force 57% more air in and you get around 116kw.
But 22 of those kw are needed to drive the supercharger, leaving a total of 94kw or 127hp.

Thanks - I thought they were 110 stock, and for some reason I used 1.46 instead of 1.36 for kW to hp.