OK I'm fairly new here and I never post. I have a 2002 Maxima with the VQ35DE engine (same as 03-04 350z) and a 6 speed manual tranny. So far I have Headers. 3" cattback exhaust, custom SFR intake manifold, 3.5" intake tubing, Intake spacers, fidanza flywheel, UD pulley, SPEC stage 2 clutch.......Haltech 350z Platinum Pro with the Haltech dual channel wideband with 2 widebands (one in each header). It made 275whp on a crap tune...anyway.

Im getting ready to do a custom turbo build...I have a 6266 Precision dual ceramic ball bearing turbo, and going to run on a 7psi spring off a turbosmart wastegate, intercooler and a LOUD turbosmart supersonic BOV!!

My question is that I was talking with my builder and the spacing is tight under the car for a 3" downpipe to go from the turbo to the exhaust because of the way the engine is it has to pass really close to the tranny. The Maxima engine is turned 90 degrees and its weird. Im keeping the block stock and expect about 380-400whp from the setup...nothing crazy like the cars I seen here!! (thats in the future)...

The turbo is a V-band with a .82 A/R and the exhaust side out the turbo looks to be 3". My builder said it would be difficult, but not impossible to do a 3" downpipe past the tranny but a 2.5" would be easier. He said 3" might be too big but this is a 3.5L V6 and not a 2.0L 4 cylinder. I just wanted to know what are your opinions on here? 2.5" or 3"? and why? I appreciate all the comments and suggestions...thanks...

PS: I also have a 2009 Maxima Throttle body (75mm vs. the 70mm stock Maxima TB) So should I go with 3" intake piping as well or 2.5" intake piping for that?

 

you want 3" piping for everything, hot and cold.

have your fabricator do it properly and not cut corners just becuase its easier.

 

for stock block power?


A small section of 2.5" downpipe before your exhaust shouldn't cause issues on the power you will be producing. What kind of exhaust is it? If it's not a straight through design it will provide more backpressure than that 2.5" section of downpipe.

If it can be made 3" (which is the output on the turbo) then that is the best thing to do but when you aren't looking for big power and the 3" will cause issue the 2.5" should be ok.

 

id agree.. the stock block thing stuck out to me.. OP.. with that gear, you are REEEEALY underplaying your power abilities without a built block. I mean i guess it will be fun as is and you can always upgrade.. but 7 psi on a 6266 is going to be a waste haha.

I have a 6266 and am shooting for triple that while on a built block..

just a heads up.. sounds like u know whats up... but dang..what a waste of potential haha. ( not meant in a bad way)

 

Its not a straight through. It has a high flow cat and a decent sized resonator. Its a Cattman Catback 3" exhaust. I dont think its really that restrictive. Its pretty quiet, given the fact that its a 3" exhaust. At idle you really cant hear it at all and sounds VERY VERY good at top. Everywhere I go I get compliments on that exhaust. Especially when I go to shops that do 350zs all the time I've had many shops tell me that my 3" exhaust sounds better than any 3" exhaust they ever installed for a 350z. They ask what kind of exhaust I got and I tell them and most of them never heard of "Cattman." Its a small company that does Maxima/Altima exhausts and headers.

I was actually talking with some people that turbo VQ35s and they said that for the power Im talking about a 2.5" downpipe will not harm anything. Thats what Im going to go with.


THANKS!!


Well......I know this the 350z forum and yall guys will not think twice about dropping $6k into a full engine build and thats OK....why would I want to put 800hp on a FWD car? If I had a RWD 350z then I'd do that. I dont think its a waste.....not everyone wants (or can afford) to dump $17k plus on full engine builds; cams, rods, pistons, oil pumps, cams, valve springs, port jobs and a turbo kit to get 900hp. On a FWD Maxima thats a waste....I would just get a 350z if I wanted to do all that.

The car will be loads of fun. I see 400-450whp turbo 350z all the time on STOCK blocks......not everyone is trying to get 900hp.

 

3" on everything... You will enjoy the power, it will be tons of fun... Keep it breathing well just in case you decide to up the power down the road.

 

If it's not a straight through design it will be restrictive. Not for your power goals but it will definitely flow less than the 2.5" short piece of downpipe. My borla true dual has more cross sectional area than a single 3" but since it all went into a baffled muffler it was highly restrictive around 530hp. Put in an exhaust cutout to bypass the exhaust muffler and i pushed it up to 652hp. Huge difference in flow.

so no, stock block power, cats, baffled exhaust the 2.5" section of downpipe won't really be an issue for restriction.

 

Thanks!!!