Sizing Intake For Big Turbo

[silvapain]

My K04 is smoking pretty bad at 85K miles, so I'm prepping for a BT swap and I know my CP-e Nano intake and CorkSport TIP aren't going be sufficient. The problem I have is that I'm not sure just HOW big I need to go.

What I know:
1. I want an intake large enough so that the MAF isn't maxed out and the restriction isn't too bad to the turbo.

2. I don't want to just buy the largest intake out there, as the larger the MAF housing the worse the resolution on the sensor, and you can have idle issues.

3. Any larger than a 3" intake and I will have the extra expense of a smaller battery and tray. I just bought a new $200+ stock size battery a couple months ago.

4. For a new turbo I will either go BNR S3 or ATP GTX3071.

For those of you with these turbos, what MAF g/s & voltage are you hitting and how large are your intakes? Science nerdism and über calculations are welcome.
@Dano; @Ziggo; @atvfreek; @rfinkle2; @phate; @cld12pk2go;

[atvfreek]

Originally Posted by silvapain My K04 is smoking pretty bad at 85K miles, so I'm prepping for a BT swap and I know my CP-e Nano intake and CorkSport TIP aren't going be sufficient. The problem I have is that I'm not sure just HOW big I need to go. What I know: 1. I want an intake large enough so that the MAF isn't maxed out and the restriction isn't too bad to the turbo. 2. I don't want to just buy the largest intake out there, as the larger the MAF housing the worse the resolution on the sensor, and you can have idle issues. 3. Any larger than a 3" intake and I will have the extra expense of a smaller battery and tray. I just bought a new $200+ stock size battery a couple months ago. 4. For a new turbo I will either go BNR S3 or ATP GTX3071. For those of you with these turbos, what MAF g/s are you hitting and how large are your intakes? Science nerdism and über calculations are welcome. @Dano; @Ziggo; @atvfreek; @rfinkle2; @phate; @cld12pk2go;

The 3" intakes will get you up to 450 without a problem on a speed 3. So if you want much more power than that, I would go 3.5.

I'm usually around 4.5 volts on the SURE 3" I.D. maf housing and that is making a little over 400hp

[rfinkle2]

The real world data that atvfreek collected will be valuable to this since he swapped intakes while tuning.

If you wanted more theoretical calculations, this covers the necessary filter area, but doesn't go into pipe size.

Air Filter | Turbobygarrett

[Vader]

GTX3071

3" CP-e MAF

CP-e whale penis.

~335-345 up top in an old, but the latest log I have.

Good thing about the CP-e, is it's silicone, so it has give to make it past the ECU/Batt tray.

Logs attached.

datalog1_60f.csv

datalog1_78f.csv

[burn813]

@silvapain; I am running a 3.5 in htp whale penis and it seems to be handling the requirements of the gtx3071r ImageUploadedByTapatalk1361201876.754889.jpg

[MS3-a(sore)ASS-rex]

4" just man up and relocate the battery to the trunk. Lol

[burn813]

I am on my phone or I would post the log along with it

[silvapain]

Originally Posted by MS3-a(sore)ASS-rex 4" just man up and relocate the battery to the trunk. Lol

I've thought about a battery relocation. If I did I'd like to recess mount it in to the floor pan so I don't loose trunk space.

I still wouldn't go 4" though. That seems too big for the turbos I'm looking at.

[superskaterxes]

Originally Posted by atvfreek The 3" intakes will get you up to 450 without a problem on a speed 3. So if you want much more power than that, I would go 3.5. I'm usually around 4.5 volts on the SURE 2.78" I.D. maf housing and that is making a little over 400hp

fixed


you should be fine with the CPE 3.25"

i would go with cld12pk's advice since he is running the GTX3071 into lala land which im sure you will be doing lol

[warlord]

Just for some perspective. Here's a list of the available stock diameter maf intakes and what they will flow at 5 volts. I compiled this list when I was contemplating a BNR and wanted to see if the standard aftermarket intakes would handle it.

All g/s are max flow at 5v. Data is from Cobbs maf calibrations.
1. Injen CAI ................411 g/s
2. K&N SRI .................384 g/s
3. COBB SRI ...............383 g/s
4. CP-E NANO SRI .......363 g/s
5. CP-E CAI ................362 g/s
6. HKS SRI .................356 g/s
7. SURE SRI ...............347 g/s
8. CORKSPORT SRI .....345 g/s
9. STOCK AIRBOX .......329 g/s

[Dano]

I am running the JBR 3.5 OD intake which absolutely requires an ECU relocate [a la Ziggo] but I went with the HTP battery tray and smaller bat as well. My OEM sized battery was only 3 MO at the time so I feel your silvapain.

My tuning was suspended due to the fact my wg was over ported and I was having boost control issues but my highest g/s was 380ish around 24PSI and voltage in the 4.2 range with zero scaling for my E30 map. I have not turned on my meth yet either.

I have no scientific evidence to add to this discussion other than the logs.

[Ziggo]

Anything much over 3.5" and you will probably have idle issues and throw the crank position sensor cel. This is because the airflow won't be sufficient at idle to move the MAF voltage off its baseline. At that point the blow thru is the better option.

I personally have a JBR 3.5" with no airflow straightener and have had no issues with fit or tuning. I still have a stock battery tray, I just relocated the ECU to the top of the fuse box.

As for gains, I dunno, I never got really aggressive with the old intake, a MSCAI, which was at 4.95v when I made the switch. Now it runs about 4.1 to 4.2v peak. If I ever make it back to the dyno I will compare the back pressure measurements which should be a good indicator of the effort from the turbo.

Zigatapatalka

[Dano]

oh and I did get the crank cell so zeroing out the maf up to .98 was required to correct this. no idle issues what so ever and I have the honeycomb.

i might have a GT28 for sale in the near future

[forcedinduktion]

Originally Posted by Dano oh and I did get the crank cell so zeroing out the maf up to .98 was required to correct this. no idle issues what so ever and I have the honeycomb. i might have a GT28 for sale in the near future

*cough *cough

[superskaterxes]

Originally Posted by Ziggo Anything much over 3.5" and you will probably have idle issues and throw the crank position sensor cel. This is because the airflow won't be sufficient at idle to move the MAF voltage off its baseline. At that point the blow thru is the better option. I personally have a JBR 3.5" with no airflow straightener and have had no issues with fit or tuning. I still have a stock battery tray, I just relocated the ECU to the top of the fuse box. As for gains, I dunno, I never got really aggressive with the old intake, a MSCAI, which was at 4.95v when I made the switch. Now it runs about 4.1 to 4.2v peak. If I ever make it back to the dyno I will compare the back pressure measurements which should be a good indicator of the effort from the turbo. Zigatapatalka

i have a 4" MAF and i have ZERO idle issues FWIW

Originally Posted by Dano oh and I did get the crank cell so zeroing out the maf up to .98 was required to correct this. no idle issues what so ever and I have the honeycomb. i might have a GT28 for sale in the near future

i believe the WSM calls out for .7v as the threshold for this code. with my 4" MAF i idle at around .95v so i needed to stay a little more conservative with my zeroing lol.

[forcedinduktion]

Technical Articles

[Dano]

Originally Posted by superskaterxes i have a 4" MAF and i have ZERO idle issues FWIW i believe the WSM calls out for .7v as the threshold for this code. with my 4" MAF i idle at around .95v so i needed to stay a little more conservative with my zeroing lol.

yeah exactly...how far up you need to zero the maf will depend greatly on your individual setup. Per Ziggo I zeroed out up to KOEO and that wasn't enough so I went up to .8ish but that still wasn't enough at times. my hot idle is 1.1 so I still have 3-4 cells of buffer.

not sure about the WSM min voltage for the check I know for a fact it didn't work on mine...that is to say I had to zero out above that.

a trick you can use to test your maf for this is to not get in a hurry starting the car...turn the key on and wait at least 5 seconds before you stat the car. IIRC it will take about 2-3 key cycles to gen the CEL if the ECU still isn't happy with the maf VT to crank rotation... or lack thereof.

[Lex]

I've seen a lot of intakes so I will chime in.

A 3" all the way to the turbo will be a good fit for an S3 or GT30 unless you want to relocate the battery.

Not all 3" intakes are the same in terms of the MAF. The HTP will max the fastest - close at about 400 g/s which is difficult on the BNR S3 but more of a possibility of the GT30.

The SURE MAF housing is 3" where the sensor sits so that one gives you more headroom and maxes out at 440 g/s. Matching this intake with a 3" TIP is not a bad idea.

Past this point you should be on a larger turbo and will likely need to relocate the ECU/have a small battery tray. Not sure if CPE falls into this category but HTP and JBR do.

The CPE is larger still and good to 530 g/s but the lack of the valve cover vent fitting is not great in my opinion.

The HTP 3.5" is good to 550 g/s but in general I find their MAFs to be more difficult to calibrate due to the straightener and how it is mounted in the intake.

JBR's 3.5" will max at around 580 g/s but on some cars finesse is needed for the low throttle and idle MAF calibration regions. Pretty sure you can handle the tuning side however.

[burn813]

You can get the htp without the straightener if you want I believe

[silvapain]

My only qualm with running a separate intake & TIP is that you can only get the larger turbo TIPs in silicone. I was planning on using the larger intake/TIP on my K04 prior to going BT, and I can't do that with a silicone TIP due to compressor inlet diameter differences. With the metal TIP I can just buy two different silicone couplers to switch back and forth between K04 & BT.

[Lex]

Just get an HTP 3" TIP, 45" elbow and the MAF of choice. SURE 3" is a good MAF sized for this or you can even get something more generic.

[atvfreek]

Originally Posted by Lex Just get an HTP 3" TIP, 45" elbow and the MAF of choice. SURE 3" is a good MAF sized for this or you can even get something more generic.

That's exactly what I run on my car. HTP 3" inlet, 45* coupler to the SURE maf housing and AEM dryflow filter. Frankenstein of sorts, but it does the trick!

[Lex]

Forgot to mention, whichever intake you get, get the AEM or Amsoil dryflow filters. The performance difference is well worth the price. I know JBR ships with these filters, SURE does not.

[breakfstincluded]

Yes the Sure 3" maf is a a good maf size, just like the one that's never been used I just posted for sale ;D

[blackms3_71]

So the htp 3" maf isnt that good, say for an gtx3071r?

[Jh8909]

@Lex; since we are on the subject, what about a 3" treadstone MAF? have you ever tuned with that? I was thinking of either going HTP 3" tip 45" elbow and then dryflow filter or selling the treadstone MAF and going HTP 3" full intake.

[StayBroke]

i would just order everything thru htp, tip, maf and filter. I had 0 issues with that setup on my 3076r.

[Lex]

For the 3" HTP, I would skip the straightener and you will probably gain some g/s headroom.

The treadstone I have seen in a couple of setups but not enough to really have an opinion.

For a MAF in the 3" size I wouldn't get the honeycomb glued in.

MAF sizing should be matched to your turbo and power/flow goals - this is why I posted the point where each will hit a fuel cut.

[Voltwings]

Originally Posted by silvapain I've thought about a battery relocation. If I did I'd like to recess mount it in to the floor pan so I don't loose trunk space. I still wouldn't go 4" though. That seems too big for the turbos I'm looking at.

i knocked 300 rpm off spool going from 3" to 4" on my 3071, and picked up... 30? g/s at the same boost level, this was months ago though and i'm not terribly organized with my data logs sadly.

[btstarcher]

I'm flowing 345 with my JBR 3.5" and K04...pretty damn happy.

[Dmurray06]

A lot of good info here.

[Dano]

Daniel,

just wait and get a one piece unit when you get the bigger turbo...no need to change up now and then again when you go BT.


HTP or JBR 3.5 is my vote...and HTP is currently selling the intake + bat tray as a package deal.


oh and I am SURE I will SUREly ridicule you if you buy a SURE intake or any other SURE product.

[silvapain]

Originally Posted by Dano Daniel, just wait and get a one piece unit when you get the bigger turbo...no need to change up now and then again when you go BT. HTP or JBR 3.5 is my vote...and HTP is currently selling the intake + bat tray as a package deal. oh and I am SURE I will SUREly ridicule you if you buy a SURE intake or any other SURE product.

You know me: always doing things backwards. Beans above the frank.

[dpolseno41]

I have the 3.5 JBR with stock battery, fits fine with a battery tray I made. Incredibly simple tray at that. I could always make you one if you're interested.

EDIT: ECU did have to go on top of the fusebox however.

[Lex]

Originally Posted by btstarcher I'm flowing 345 with my JBR 3.5" and K04...pretty damn happy.

There is something up with the 345 because there is no way a K04 flows 345 true g/s working in the arctic and with 5" piping on each end . Most BNRs don't even flow that much at 23psi so the MAF calibration must be off. However the larger JBR intake may get you over 300 g/s in the winter.

[cld12pk2go]

I made 469whp with the CP-E Nviscid TIP with the CP-E 3.25'' MAF. From memory, I think I haven't been over 4.55v. I have about 100g/s left.

I have since replaced the relatively small ~4.5'' air filter that comes with the 3.25'' MAF kit (since my dyno operator thought it was too small at my power level) with a 7'' AEM Dryflow, but snow/rain/travel has prevented me from getting any comparative data with the new filter yet.

If you aren't looking for more than 450whp, then any 3'' TIP and the CPE-E MAF will work great. I currently suspect that it is a restriction on my setup though. I am currently hedging that the bulk of the restriction was at the filter...

If I was starting from scratch and looking for 500whp, I would get a full 4'' TIP/MAF with a 7'' or 9'' AEM Dryflow filter (the biggest that could be made to fit).

I was considering the HTP 4'' and cutting it up a little and adding a silicone coupler or two to make it fit (length and orientation to work with my meth tank and the larger air filter), but have since settled on just the filter upgrade for now.

Obviously, at minimum the ECU will have to be relocated on a 4'' setup.

[Dano]

Originally Posted by silvapain You know me: always doing things backwards. Beans above the frank.

haha forgot about that...built HCR motor on K04.... backwards...

[phate]

Originally Posted by Dano haha forgot about that...built HCR motor on K04.... backwards...

Maybe it's the rest of you doing it backwards........

[forcedinduktion]

Originally Posted by Lex Just get an HTP 3" TIP, 45" elbow and the MAF of choice. SURE 3" is a good MAF sized for this or you can even get something more generic.

This is what im gonna run

[cld12pk2go]

Originally Posted by cld12pk2go I made 469whp with the CP-E Nviscid TIP with the CP-E 3.25'' MAF. From memory, I think I haven't been over 4.55v. I have about 100g/s left. I have since replaced the relatively small ~4.5'' air filter that comes with the 3.25'' MAF kit (since my dyno operator thought it was too small at my power level) with a 7'' AEM Dryflow, but snow/rain/travel has prevented me from getting any comparative data with the new filter yet. If you aren't looking for more than 450whp, then any 3'' TIP and the CPE-E MAF will work great. I currently suspect that it is a restriction on my setup though. I am currently hedging that the bulk of the restriction was at the filter... If I was starting from scratch and looking for 500whp, I would get a full 4'' TIP/MAF with a 7'' or 9'' AEM Dryflow filter (the biggest that could be made to fit). I was considering the HTP 4'' and cutting it up a little and adding a silicone coupler or two to make it fit (length and orientation to work with my meth tank and the larger air filter), but have since settled on just the filter upgrade for now. Obviously, at minimum the ECU will have to be relocated on a 4'' setup.

I ran some numbers to try to obtain an estimate of the expected pressure drop through 3'' and 4'' intakes, since I was admittedly winging it using my engineering SWAG previously...

Please feel free to check my assumptions, but this online calculator shows only 0.11 PSI pressure drop at 65 lbs/min flowrate with a 3'' ID/2.5ft long pipe. This compares to 0.03 PSI pressure drop with a 4'' ID pipe. Edit: I also ran this for 2.5'' ID intake and got 0.28 PSI (non-trivial)...

I wouldn't consider 0.08 PSI difference to be very significant compared to the expected DP through the filter which should be something like 3-10x that much depending on size/type...

So unless I messed up the calc, it seems like going larger than 3'' hits diminishing returns quickly at least at the 65lbs/min flowrate threshold.

Pressure Drop Online-Calculator

My assumptions/results: