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Can anyone here confirm that the factory OEM MHI TD03 on the Si is larger than the 1.5T EX turbo? And are there any big definitive differences between the internals of these two motors?
 

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I don't have the info to back this up but I thought I read that the engine is identical and the HP comes from the ECU tune and in this case, unlike the sport, the exhaust system. But again I'm not positive on this.
 

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The SI and CRV Turbo I believe has a different number of vanes on the compressor wheel.I don't think it's bigger
 

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The SI also has a lower compression ratio.I also believe the Sport button changes the throttle map to give a more spirited performance feel.The increased HP is a different ECU calibration I believe also.
 

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Can anyone here confirm that the factory OEM MHI TD03 on the Si is larger than the 1.5T EX turbo? And are there any big definitive differences between the internals of these two motors?
1. No, its not larger - it just flows more because there is less restriction in the exhaust path 9 blade Si vs 11 blade EX

2. Yes - the engine in the Si is said to have better bearings, lower compression and stronger rods. Part numbers will eventually confirm the differences but knowing Honda it makes sense.

They are fully aware Si owners will drive much more agressively than grandma in her EX.

What seem like small changes add up.
If you look at the MAF placement, our larger intakes etc....Honda thought this well beyond just an EX + more boost

Even the Si lower grill is larger to flow more to the intercooler.

The mechanical fuel pump for the direct injection isalsi better on the Si meaning it can support more boost/power before running out of fuel.

As time passes we will learn more.....but if anyone thinks the engines are exactly the same, they are wrong
 

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The important part isn't the turbo size...
...it's the differential.

The 1.5T cars have an open differential, that means once one wheel starts spinning, it'll spin. One wheel peel (one wheel traction!).


The Si has a limited-slip differential, and that means once one wheel starts spinning, torque routes to the other wheel. You get TWO wheels worth of traction.

Honestly - if the smaller motor was in the Si and the bigger one in the other Civics, this would still be enough of a performance advantage to opt for the Si and target HP improvements afterwards.

Yes - I have the 1.5T Sport hatchback and not an Si, but that's because I wanted a cheap-to-insure car that's 90% commuter-mobile. For performance, the Si is the ticket - for all the OTHER reasons that aren't the turbo. Just want to make sure you aren't focused narrowly on that. ;)
 
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