[drocksmooth]

Hello! I just recently purchased a 2010 BMW 335i and I'm loving it! It's my first BMW and my first turbocharged car so I've been researching previous posts and "getting smart" on how a turbo engine works and the best way to mod it. I'm new to this forum, but not new to modding. My last car was N/A and I put in a high lift cam, ported heads, high-flow headers/mids and cat back exhaust. Put in an LSD rear dif to get the power to the wheels and, of course, a custom tune to bring it all together. As a result, I've ascribed to the old saying "there's no replacement for displacement," but it seems that with the turbocharged cars this maxim doesn't necessarily hold true. All the mods I see are centered around the turbochargers and I'm trying to find out why? With my old N/A car, ported heads and an aggressive cam (with a good tune) yielded the most power increase. I have researched porting heads and upgraded cams on this forum, but those posts were on the N/A forums, not the turbocharged forums. Can someone please explain to me why displacement (and cams) is ignored in turbo cars?

On a related note, there was a lot of argument in my old forum about the need to increase air volume within engines since the amount of air the filters are able to suck in is limited by the size of the throttle body. With turbo engines, if we were to increase the amount of air generated by the compressor, wouldn't all that air be limited by the size of the throttle body? I don't see any posts about the benefits of increasing throttle body size though. Thanks in advance!

[Miller335]

Think of an engine as an air pump.

If you force feed it air, you've increased it's air pumping ability.

There are drawbacks to "increasing displacement" this way but that doesn't stop us from having our fun.

[drocksmooth]

Originally Posted by Miller335

Think of an engine as an air pump.

If you force feed it air, you've increased it's air pumping ability.

There are drawbacks to "increasing displacement" this way but that doesn't stop us from having our fun.

Thanks for the response! But even if you use a firehose to force feed the air, you're still hampered/limited by the size of the nozzle, right? The bigger the nozzle (i.e. throttle body), the more air flowing into the intake manifold.

Just thought of another question, if the air coming in through the filters eventually is cooled by the intercooler before entering the intake manifold, does it really matter that it's a "sealed system" or that there is some heat soak from the engine? I've been looking at the AFE "sealed system," but thinking about it, if the air is going through the intercooler, then there isn't really a need for a "sealed system," right?

[csu87]

Well people are at 800+whp on stock block so no porting and cams needed. Just a big single turbo, some meth and e85.

As for intake heat soak, no difference since the turbo heats up the air. Read this http://www.n54tech.com/forums/showthread.php?t=23993

[drocksmooth]

Originally Posted by csu87

Well people are at 800+whp on stock block so no porting and cams needed. Just a big single turbo, some meth and e85.

As for intake heat soak, no difference since the turbo heats up the air. Read this http://www.n54tech.com/forums/showthread.php?t=23993

Thanks! Like I said, turbos are new to me, just trying to understand why. Gotta read up on the benefits of meth . . .

Thanks for the link!

[JDuke335i]

Originally Posted by drocksmooth

Thanks! Like I said, turbos are new to me, just trying to understand why. Gotta read up on the benefits of meth . . .

Thanks for the link!

Look up vacmotorsports. They port heads for the n54.

[924er]

But will it be reliable ?
#theanxiom

[AndyW]

Originally Posted by drocksmooth

Thanks for the response! But even if you use a firehose to force feed the air, you're still hampered/limited by the size of the nozzle, right? The bigger the nozzle (i.e. throttle body), the more air flowing into the intake manifold.

Just thought of another question, if the air coming in through the filters eventually is cooled by the intercooler before entering the intake manifold, does it really matter that it's a "sealed system" or that there is some heat soak from the engine? I've been looking at the AFE "sealed system," but thinking about it, if the air is going through the intercooler, then there isn't really a need for a "sealed system," right?

I am not and expert but generally, a turbo(or supercharger) allows compression of the air (density goes up) therefore more fuel can be mixed with that air per cylinder firing for the same AFR, therefore more power with a smaller engine. Also, these are direct injection engines so the fuel metering can be very precise.

WRT the intercooler...different trains of thought exist (do a search on CAI vs DCI on the forum to see some heated debates). Tests have shown that air flow in the engine bay makes a DCI or inlets work fine although technically a CAI will get *slightly* better cooling of the air into the turbos. My unqualified online research indicates it is probably a wash, performance-wise. WRT FMIC, the stock intercooler is too small. Getting an aftermarket FMIC is probably the biggest initial performance jump you can give the N54 engine. YMMV.

[Sgop335]

Originally Posted by drocksmooth

Hello! I just recently purchased a 2010 BMW 335i and I'm loving it!

On a related note, there was a lot of argument in my old forum about the need to increase air volume within engines since the amount of air the filters are able to suck in is limited by the size of the throttle body. With turbo engines, if we were to increase the amount of air generated by the compressor, wouldn't all that air be limited by the size of the throttle body? I don't see any posts about the benefits of increasing throttle body size though. Thanks in advance!

That argument is true upstream of the turbo meaning suction side. Downstream there is boost and air is compressible! So volume flow rate may be same or even less but mass flow rate goes up. And power is directly prop to mass flow rate not volume flow. Get it?