300hp from a 4BT with a single turbo has always been a bit of a mirage. Sure you can do it with a dyno queen, but can you do it with driveability?
I ran through the 250hp power recipe and cranked it up a bit to see what would stop us.
I kept fuelling at the 180cc/1000 shot limit you get from a VE pump. To see if that was possible.
I used the flow limits I expect from the turbo known as the HX30 Super with a 46/73mm compressor and 6cm turbine housing.
I set intercooling to 80% heat rejection
![Image]()
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I kept air/fuel ratio at a safe 18:1.
I used sea-level and 20C as the test conditions.
I used the same Volumetric Efficiency (VE) curves as the other power recipes (0.9 at idle dropping to 0.76 at 3000rpm).
I used the same BSFC (fuel to power) numbers as previous (min 214g/kwh at 2000rpm, 257g/kwh at 3000rpm).
RPM is naturally limited. You can't build more power past about 3000rpm.
I used the HE221 compressor map for flow, but the HX30 Super will have higher boost capacity.
I used 65% compressor efficiency (we are going up the surge line, across the top and to the edges)
I used
Here's what I found:
36psi boost is about right. Less will give you smoke, more will waste power.
180cc/1000 shots isn't quite enough fuel.
Driveability will be okay.
Max torque is pretty flat from 1700-2300rpm.
Max power is about 3100rpm.
Compressor is tapped out for flow at max power.
EGT will be high but safe.
Some numbers:
2000rpm torque: 818Nm (603ft-lb).
3000rpm power: 213kw (285hp) after accounting for drive pressure losses.
36psi boost from 1700rpm to defuel just after 3000rpm.
Drive pressure equal to boost at 2000rpm, tapering to +12psi (48psi total) at 3000rpm.
A/F ratios 21:1 at 1700rpm tapering to 18:1 at 3000rpm.
Fuelling: 180cc/1000 shots at your actual injectors (test bed injectors can be different).
Air Filter: 500CFM (36lb/min).
Turbo shaft power: 52kw.
Intercooler heat rejection: 41kw.
So how do you actually get 300hp with a single turbo?
You need either a custom built VE pump with bigger plungers or a P pump.
You need a turbo that's 48-50mm intake but still spools well. I haven't found one but I haven't looked that hard.
Compounds will be easier, cleaner and have plenty of head-room for altitude.
Here's a pretty picture, torque on the left, everything else on the right axis:
![Image]()
![Image]()
I ran through the 250hp power recipe and cranked it up a bit to see what would stop us.
I kept fuelling at the 180cc/1000 shot limit you get from a VE pump. To see if that was possible.
I used the flow limits I expect from the turbo known as the HX30 Super with a 46/73mm compressor and 6cm turbine housing.
I set intercooling to 80% heat rejection
I kept air/fuel ratio at a safe 18:1.
I used sea-level and 20C as the test conditions.
I used the same Volumetric Efficiency (VE) curves as the other power recipes (0.9 at idle dropping to 0.76 at 3000rpm).
I used the same BSFC (fuel to power) numbers as previous (min 214g/kwh at 2000rpm, 257g/kwh at 3000rpm).
RPM is naturally limited. You can't build more power past about 3000rpm.
I used the HE221 compressor map for flow, but the HX30 Super will have higher boost capacity.
I used 65% compressor efficiency (we are going up the surge line, across the top and to the edges)
I used
Here's what I found:
36psi boost is about right. Less will give you smoke, more will waste power.
180cc/1000 shots isn't quite enough fuel.
Driveability will be okay.
Max torque is pretty flat from 1700-2300rpm.
Max power is about 3100rpm.
Compressor is tapped out for flow at max power.
EGT will be high but safe.
Some numbers:
2000rpm torque: 818Nm (603ft-lb).
3000rpm power: 213kw (285hp) after accounting for drive pressure losses.
36psi boost from 1700rpm to defuel just after 3000rpm.
Drive pressure equal to boost at 2000rpm, tapering to +12psi (48psi total) at 3000rpm.
A/F ratios 21:1 at 1700rpm tapering to 18:1 at 3000rpm.
Fuelling: 180cc/1000 shots at your actual injectors (test bed injectors can be different).
Air Filter: 500CFM (36lb/min).
Turbo shaft power: 52kw.
Intercooler heat rejection: 41kw.
So how do you actually get 300hp with a single turbo?
You need either a custom built VE pump with bigger plungers or a P pump.
You need a turbo that's 48-50mm intake but still spools well. I haven't found one but I haven't looked that hard.
Compounds will be easier, cleaner and have plenty of head-room for altitude.
Here's a pretty picture, torque on the left, everything else on the right axis:
