Engine Performance

[Scot]

Hi All,

I have a 4.0 L V8 Lexus motor in my dirt oval racing car. Currently I'm running the RPM's at 7500 with no problem at all. I'm now going from dirt oval to tar oval and need more RPM's and want to step it up to 9000 with 106 octane fuel.

Will the motor be able to handle the up in RPM's. The motor is still standard.

 

[PR_SC400]

What mods have you done to the engine? Valve springs are going to need to get upgrade, if you haven't rebuillt the engine now would be a good time to get your crank, rods and pistons balanced.

But I have very limited experience with these engines some of the other guys should chime in soon.

 

[stevechumo]

It's amazing how this engine can handle, but the key is how long it'll hold without strenghtening the internals.

 

[PR_SC400]

Wont he run into valve float past 8k?

 

[XR8tt]

I would say hes close to valve float all ready..
The std valve spring pressure is 50LB and every Jap import engine
I have checked are running just under that...
Second hand motors are so cheap..
Imo buy another and fit forged rotating assembly with the lightest forged rods and pistons available if keeping N/A.. Then fit performance cams, better valve springs...
Atleast fit some better springs to what you have..

 

[PR_SC400]

I would say hes close to valve float all ready..
The std valve spring pressure is 50LB and every Jap import engine
I have checked are running just under that...
Second hand motors are so cheap..
Imo buy another and fit forged rotating assembly with the lightest forged rods and pistons available if keeping N/A.. Then fit performance cams, better valve springs...
Atleast fit some better springs to what you have..

Best option that way your car wont be down or you could get a 97+ engine with an upgraded valvetrain.

 

[Scot]

Thanks guys, appreciate the feedback