has anyone every tried swapping out the bottom end of a 350 onto the 250 head and electronics, just to have the bigger 3.5 bottom end and will it bolt up?

 

Has someone tried this...no. Is it even possible to run 2.5L heads on the 3.5L bottom end...probably not.

 

Even if the heads fit, the 4GR-FSE ECU wouldn't know what to do, it's a similar situation to installing a supercharger or turbo.

The 3GR-FSE might be closer.

Jeff

 

I don't think it can be done my friend.If you want to gain power from an IS250 easy make a supercharger set up.A Rotrex C30-94 is perfect for this engine.The gains will be almost 50 horsepower and the car will be fun enough.I wish we had 350s in Europe but since we don't this is the only way to gain some power for this car!Only if Jeff could tell for sure that we don't need all VDIM ecus to run 350 engine manual it will certainly worth more!

 

My concern is not electrical it's mostly if everything will bolt on the is 250 and use all the stock electronic that the car comes with, I can always piggy back a ecm to control injector and timing

 

Compare the headgaskets first

 

Yeah I was thinking that, some one has to try it out

 

The blocks looks the same so everything should bolt up mechanically

 

You said something about Rotrex supercharger, but what about the fueling and timing issues?

 

My friend Elias has an LMS supercharger for a few years now.You can only boost 0.5 bar with stock ECU.No extra fuel is needed.He added a meth kit and gained 10 extra ponys and thats it.I know for sure that you will not have a problem in that boost

 

Then it's possible to swap out the 350 block in place of the 250 if it's mechanically the same and the ecu may compensate for additional litre

 

I wish it can