Supercharger Boost Pressure Calculations

[Dimitris Papamichail]

I read many posts regarding the boost pressure that the TTE supercharger and the engine motor of the IS200 can handle and my conclusion was that many owners that were interested to increase the boost of their supercharger were not certain if it was safe or not. So I decided to do some research regarding the crank shaft pulley that can be fitted on the IS200 motor in order to increase the boost pressure of the TTE supercharger.

Firstly I found the specifications of the Eaton M62 supercharger, which are the following:

Eaton M62:

Displacement: 1.035 liters = 1035cc

Max. Outlet Pressure: 2.0 Bar

Max Speed Cont (inst.): 14,000 (16,000)

Flow at Max. Speed @ 1.8 Bar: 810 cubic meters / hour.

Then I did some research and dug out my old university books to find out how to calculate the boost pressure.

Lexus IS200 engine:

Engine max rpm: 6250

TTE crank pulley dia.: 130mm

Eaton Supercharger pulley dia.: 100mm

Ratio: 130/100= 1.3

From the Eaton specs I have mentioned above the M62 flows 1035cc per crank turn. Therefore we have,

1035cc x 1.3 = 1345.5cc per crank turn

1345.5 - 999 (1/2 engine cc) = Extra flow of 346.5cc per crank turn

346.5/999 = 0.35 bar

At max engine rpm the max speed of supercharger is: 1.3 x 6250 = 8125 rpm

If we repeat the above procedure for a larger crank pulley, ie. dia. = 140mm the boost pressure will be 0.45bar and the max speed of the supercharger will be 8750 rpm and so on.

[Rob]

I read many posts regarding the boost pressure that the TTE supercharger and the engine motor of the IS200 can handle and my conclusion was that many owners that were interested to increase the boost of their supercharger were not certain if it was safe or not. So I decided to do some research regarding the crank shaft pulley that can be fitted on the IS200 motor in order to increase the boost pressure of the TTE supercharger.

Firstly I found the specifications of the Eaton M62 supercharger, which are the following:

Eaton M62:

Displacement: 1.035 liters = 1035cc

Max. Outlet Pressure: 2.0 Bar

Max Speed Cont (inst.): 14,000 (16,000)

Flow at Max. Speed @ 1.8 Bar: 810 cubic meters / hour.

Then I did some research and dug out my old university books to find out how to calculate the boost pressure.

Lexus IS200 engine:

Engine max rpm: 6250

TTE crank pulley dia.: 130mm

Eaton Supercharger pulley dia.: 100mm

Ratio: 130/100= 1.3

From the Eaton specs I have mentioned above the M62 flows 1035cc per crank turn. Therefore we have,

1035cc x 1.3 = 1345.5cc per crank turn

1345.5 - 999 (1/2 engine cc) = Extra flow of 346.5cc per crank turn

346.5/999 = 0.35 bar

At max engine rpm the max speed of supercharger is: 1.3 x 6250 = 8125 rpm

If we repeat the above procedure for a larger crank pulley, ie. dia. = 140mm the boost pressure will be 0.45bar and the max speed of the supercharger will be 8750 rpm and so on.

the supercharger is not directly driven by the crank pulley so your calculations dont mean anything unfortunatly!

have a look under the bonnet and you will clearly see it is driven by the waterpump and due to the various pulleys involved the water pump SC drive pulley rpm is totally different to crank rpm.

It has been shown that the pulley mounted on the SC reaches 10,300 rpm at max engine rpm so your figure of 8125 rpm is incorrect. it is also worth noting that as the pulley on the front of the SC does not directly drive the lobes of the SC but thru a set of gears, the rpm of the front mounted pulley may be different to the actual rotation of the lobes unless it has a 1:1 gear ratio - i have no inclination to check this.

If you contact patrik lindholm he may kindly measure the speed of the SC waterpump drive pulley for you and that will give you at least a solid starting point but that then leaves the question about the gear ratio on the SC itself.

[IS_man]

a valiant, noteworthy effort, none the less tho...

[Dimitris Papamichail]

Well as you said worth the try. I will try and measure speed of the sc waterpump