Lower Compression Ratio for Supercharger?
 

Hi all,

I have a 2015 GS350, but I'm posting here because our cars have the same engine and we don't have a performance section in the GS forums. I'm planning on getting the RR Racing supercharger sometime next year and was doing some research on forced induction and found that MWR makes some 10:1 compression ratio pistons for the 2GR-FSE, which is the same compression ratio that the Lotus Evora has on the 2GR-FE, which comes supercharged stock. On their site, RR Racing says that they are able to make 9 to 10 psi of boost with the stock motor and 11.8:1 compression ratio. What I'm wondering is, could more power be had by doing a piston swap to achieve a lower compression ratio and increasing the amount of boost the supercharger pushes? Let me know your thoughts...

I'm thinking you could make more power with lower compression but it wouldn't be enough of a gain to make tearing the engine down worth it. Unless you have a full shop and plenty of time and skill then sure do it. But I'm making a guess wouldn't this be something to ask RR Racing about?

We are able to make a lot of power on the stock engine with stock compression. The amount usually meets the customer's expectations. The problem with raising the power higher is that you will begin to find the limitations to the rest of the driveline so it's not recommended to push it.

-Justin
RR Sales

Something else to consider is you'll deviate from their current tune which equates to more time getting your car back to peak performance and possibly additional expenses.

That said, more boost typically equates to more heat from compression. This is heat you need to remove to keep the same timing advance or you may loose power by reducing ignition advance to minimize detonation.

Does the kit come with an intercooler? How much heat can it shed?

Most people looking for more performance on SC (fixed boost) engines raise compression and use a better fuel. Like the post above, a great intercooler or air to water will make a big difference cooling the charged air and will potentially make more power. The compression ratio isn't your limiting factor, fuel and tuning is. I believe the compressor in the RR kit can flow 5-600cfm.

The 4GS performance enthusiasts are here hanging out with the "cool kids". You're not alone. Hehehehe

Also, if you are ever in Houston, we need to compare performance recipes.....

You can also just lower the compression with thicker Head Gaskets also, can't you??