Has AMS tested the power difference between running a 4" intake vs. a 3" intake on a 35R turbo or larger setup? On my setup I'll still be utilizing the stock MAF sensor, but I'm wondering if there is more power to be had by using a 4" intake pipe w/ a reducer at the sensor. Any insight is appreciated

 

if you are still necking the inlet back to a 3" pipe for sensor, any gains will be negligable. The only gains you would have would be slightly decrease pipe flow losses from using a larger 4" pipe for a short section.

 

I was considering this if I went the 35R route but decided it would take quite a bit of tuning to get everything back in line. It wouldn't just be WOT operation either, all the lower load cruise maps would have to be dialed in with lots of datalogging and likely at a different percentage at idle, cruise, and full boost. The only reason I could see this helping significantly is if you want to drop down to a lower part of the load maps due to outflowing what the stock ECU can manage. You may be able to find someone that has dynoed a larger turbo with a 3" intake versus a 4" intake with no other changes.

 

The reason I brought this up is that it was mentioned in a dyno tuning/results thread that great gains were to be had by going to a 4" pipe over 3". I agree that the whole map would have to re-tuned as well as rescaling the maf sensor. I was told AMS has tested this out, but I'm guessing it was probably on a speed density setup if they did.

 

You would have a gain if you ran 4" without MAF I believe

 

if you are using stock maf you cannot use a 4inch intake since the maf is 3 inch.. correct me if im wrong

 

Sure you could with a 4" to 3" reducer

 

You can use a 4" to 3" silicone reducer for a full 4" intake pipe or one of these intake pipes that eliminates the silicone reducer:

 

turbohoses.com They sell a 4" to 3 1/4" reducer. The maf is 3 1/4" not 3"

 

Just buy a standalone and do 4" intake the right way.....

 

Care to elaborate any further? Why would that be considered the "right" way?

 

so you don't have neck it down

 

I understand that; his comment adds nothing to my original question though. If I want to convert to speed density I'm still able to on stock ecu; I'm not going to spend $1500 just to remove the MAF sensor.

 

Just use a 4" to 3" reducer at the turbo inlet and use a 3" intake pipe.

 

You pretty much need to run Speed Density. Removing the maf thats how you'll get a gain..... MAF makes a restriction, SO clearly a 4" intake on a 4" = 100% performance doing a 3" on a 4" is 75% AKA restriction.