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Discussion Starter #1
Looking for feedback or experience running a 3 inch intake tubing on either the 2RZ or 5VZ-FE engines (same throttle body and all that). I am getting the exhaust done next week putting on a true 2.5" exhaust through the cat (replacing with a 2.5" cat) and 3" piping cat-back. Thinking I should open up the intake even more, already have the air box opened up, intake elbow removed, high-flow filter and bored throttle body.

I have a piggyback, the AEM FIC 6. Trouble is, I've never tuned for a larger intake before. I know it'll involve taking data on the MAF voltage with the stock 2.5" intake at various pressures and RPM's then figuring out a conversion rate. I have some good data so far, just would need some for cruising speeds and such. Is it worth the trouble? Am I chasing a couple of HP that could be spend elsewhere?

Looking at picking up this adapter with a honeycomb insert: Treadstone Performance Inc., Turbo Kits, Intercoolers, Turbo Manifolds, Silicone Hose then welding on some bungs on an aluminum pipe or something like that.
 

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I used a Spectre MAF housing with good success only when I used the insert that was the same diameter as the stock MAF housing. If I tried to use any of the larger diameter housings I couldn't get good results with a piggyback. It might be possible but it was beyond my tuning abilities. The throttle response was slow and afr's were all over the place. I swapped in the stock size insert and everything worked so much better. I easily got about 300whp at 15psi with the stock size MAF housing on the pressurized side of the turbo. If you are thinking about a draw through MAF I don't think it will work well at all. I gave up on draw through very early on because the throttle response was terrible. I found mounting the MAF in the pressurized pipe about the same distance from the throttle body as stock worked best with the stock tune and a piggyback. Above 15psi I had to use rtv silicone to seal the sensor to the housing because the o-ring wouldn't hold more than 15psi when doing a boost leak test.
 

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When I got to around 400whp I had a hell of a time figuring out why my engine would pull hard and then it was just like someone turned the key off. It would just be instantly off at wide open throttle when I hit about 5k rpm and if I increased the boost pressure it would happen at lower rpm. It turned out 3" intake piping and the 3" air filter I was using was too small for 400whp+ it chokes the turbo. I only figured it out by doing a trial run with no air filter which I don't like to do. I have a 4" intake pipe and 4" K&N air filter now and it's happy close to 500whp.
 

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Discussion Starter #4
I used a Spectre MAF housing with good success only when I used the insert that was the same diameter as the stock MAF housing. If I tried to use any of the larger diameter housings I couldn't get good results with a piggyback. It might be possible but it was beyond my tuning abilities. The throttle response was slow and afr's were all over the place. I swapped in the stock size insert and everything worked so much better. I easily got about 300whp at 15psi with the stock size MAF housing on the pressurized side of the turbo. If you are thinking about a draw through MAF I don't think it will work well at all. I gave up on draw through very early on because the throttle response was terrible. I found mounting the MAF in the pressurized pipe about the same distance from the throttle body as stock worked best with the stock tune and a piggyback. Above 15psi I had to use rtv silicone to seal the sensor to the housing because the o-ring wouldn't hold more than 15psi when doing a boost leak test.
I'm at 290whp at 10 PSI, so pretty close to the limits of the 2.5" piping it seems. Was it the turbo pressure that screwed up the MAF readings you think? I have a supercharger so it's still under vacuum at the MAF though. Would that make it simpler?
 

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I'm at 290whp at 10 PSI, so pretty close to the limits of the 2.5" piping it seems. Was it the turbo pressure that screwed up the MAF readings you think? I have a supercharger so it's still under vacuum at the MAF though. Would that make it simpler?
Since you are draw through the 2.5" MAF may be even more restrictive than if it was blow through. Pressurized air is more dense so you can fit a lot more of it through a small MAF than the same setup with a draw through MAF. I think the reason the larger MAF didn't work well for me was I couldn't figure out how to re-scale both the fuel and timing tables to compensate for the larger MAF with a piggyback. Changing to a larger MAF screws up both fuel and timing tables at the same time so hard to fix without a lot of time since you don't know which table is making the engine run poorly.
 
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I'm running a 3" MAF housing. Intercooler and piping are also 3 inches.

Started off with MAF in percentage mode with +7%. I could tune, but yeah, the throttle response seemed slightly sluggish. Now, I'm at 14.8% on my MAF, as in, I've clamped the ENTIRE MAF fuel table at +14.8%. Running 318cc Bosch injectors, lowest fuel % in fuel map at idle is -25%.

You can also look at what your incoming grams per second (or lb/ft min) is in your OBD2 software for the MAF with a stock 2.5" pipe. Then, switch it over to 3" and modify your MAF map until the grams per second... or whatever units match at the same RPM/load. Fueling will need to be adjusted as well, but this method should get you started.
 

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I also ran the supercharger with a 3" MAF tube, but only had +7% in the MAF table. Supercharger tuning.... sucks man, it took me the longest out of all the tuning I've done. And, I needed to have a spring/fall maps too.
 

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Discussion Starter #9
I'm running a 3" MAF housing. Intercooler and piping are also 3 inches.

Started off with MAF in percentage mode with +7%. I could tune, but yeah, the throttle response seemed slightly sluggish. Now, I'm at 14.8% on my MAF, as in, I've clamped the ENTIRE MAF fuel table at +14.8%. Running 318cc Bosch injectors, lowest fuel % in fuel map at idle is -25%.

You can also look at what your incoming grams per second (or lb/ft min) is in your OBD2 software for the MAF with a stock 2.5" pipe. Then, switch it over to 3" and modify your MAF map until the grams per second... or whatever units match at the same RPM/load. Fueling will need to be adjusted as well, but this method should get you started.
Yeah was planning on logging voltage signal but can also view the Torque data in g/s. So you are saying you had to not only increase MAF signal on the MAF table, but also increase on the Fuel table as well? Since you did goof around with a 3" intake with a supercharger, was it worth the extra trouble or basically negligible power gains with the sluggish response?
 

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You would be adding to the MAF table, but subtracting from the Fuel table. It was very worth the trouble. Supercharger response will be snappier. MAF sensor is first sensor used in fuel trim calculations. If the system has to rely more heavily on the O2 sensor to send an accurate fuel correction for ST and LTFT, then the eventual, most powerful engine response will be delayed. But if it gets the most accurate signal from the sensor that's "first" in the fuel calculation cycle then it would stand to reason that the engines most powerful output would be delivered sooner.
 

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Discussion Starter #11
I pulled the trigger on some intake parts from siliconintakes.com. Goes from 8x6 cone filter to 3"intake tubing and MAF housing, to 45 degree bend to 3.0" to 2.5" reducer. Also adding a honeycomb insert to help straighten the airflow over the MAF, since I noticed the stock box has one and must be there for a reason.
 

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So, I'm pinging at around 9-10 psi now with my exhaust cut-out closed. I'm not pulling any timing at the moment, but because the engine isn't as "retarded" (intake size has been taken into account in MAF fuel table) due to it being more responsive, I think it needs to be told to slow down at those boost levels. Interesting development, but I've never boosted this much in this heat.

Does not ping at 8 psi and below, even during high gear/low, mid, high load transitions.
 
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