2.0L MZR header and exhaust length testing

[Grant]

tl;dr: I try some header and exhaust length tuning on a Miata motor, i.e. spend a lot of time and money to lose power. This might be educational for someone who's never done this before.

I've got a 2009 NC Miata I endurance race in ChampCar and want to run in WRL. It needs every whp it can get, so to that end I decided to try and max out the header. We started with RoadsterSport's 1.8 (1-7/8" primaries ~17" in length) MAX Power header (pics here). I assumed this was kept short to mate up with the factory exhaust system, meaning there would be gains to be had with longer runners. It was also built with the popular 2.5L swap in mind, so I reasoned the primaries might be too large in diameter.

I called Burns Stainless, who designed the header for the NP01 prototypes which use NC MZRs (though the newer NP01-Evo variant have aftermarket cams). They said they've done a lot of testing with this motor, and recommended 28" primaries (measured from collector to head flange) with 1-5/8" diameter, in 16 gauge stainless.

I also consulted PipeMax (my PMW file is here), which said 1-5/8" diameter and 20.5" length:

Code: Select all

   --- Primary Tube Specs : Race Header  •  Single Tube diameter size ---
Peak TQ Diameter Range  = 1.472 -to- 1.597  Best Length = 19.561 -to- 21.521 inches
Best Mid-Range Diameter = 1.597  Best Length = 19.561 -to- 21.521 inches
Peak HP Diameter Range  = 1.597 -to- 1.722  Best Length = 19.561 -to- 21.521 inches

   --- Primary Tube Harmonics ---    ( One-End-Closed Tube = Odd Numbered Harmonics )
1st Harmonic = 67.017 to 68.976 inches long ... typically never used ( too long to fit any Vehicle )
3rd Harmonic = 19.561 to 21.521 inches long ... highly recommended , best Torque and HP Curve
5th Harmonic = 10.070 to 12.029 inches long ... shortest recommended ( Shorty or very Hi-RPM Header )
7th Harmonic = 6.002 to 7.962 inches long ... shortest recommended ( Shorty, Hugger, or Log Style )
9th Harmonic = 3.743 to 5.702 inches long ... shortest recommended ( Log Style or Cast-Manifold )
11th Harmonic = 2.305 to 4.264 inches long ... shortest recommended ( Log Style or Cast-Manifold )
------------------------------------------------------------------------------------------------------
   --- Collector Specs : Straight Tube Collector  •  or Straight with a slight Merge shape ---
Peak TQ Diameter Range  = 1.866 -to- 1.991  Best Length= 17.093 -or- 34.185 inches
Best Mid-Range Diameter = 1.991  Best Length= 17.093 -or- 34.185 inches
Peak HP Diameter Range  = 1.991 -to- 2.116  Best Length= 17.093 -or- 8.546 inches

   --- Collector's Harmonics ---     ( Both-Ends-Open Tube = Odd and Even Numbered Harmonics )
1st Harmonic = 136.741 inches long ... longest recommended with Mufflers and TailPipes
2nd Harmonic = 68.370 inches long ... longest recommended with Mufflers and TailPipes
3rd Harmonic = 34.185 inches long ... greater Low RPM Torque -to- Peak Torque RPM
4th Harmonic = 17.093 inches long ... highly recommended , best Torque and HP Curve combination
5th Harmonic = 8.546 inches long ... reduced Peak Torque , higher RPM HP gains possible
6th Harmonic = 4.273 inches long ... reduced Low RPM Torque , even though Tuned Length

Exhaust valve to port length is 3.5". It's also a MAF car, so I don't need to change the tune for different headers.

Trusting Burn's experience, I bought a PPE 1-5/8" 16 gauge header. It has ~30" long primaries designed for lots of mid-range in autocross applications. It sucked. This is a same-day dyno of it vs. the 1.8 MAX. Both had a 20" pipe after the collector:

1.8_max_vs_ppe.jpg

I wasn't expecting it to make the top-end of the MAX, but I'd thought it would beat it somewhere. I then hacked the collector off and slid on a Burn's collector. Both these pulls had no pipe after the collector:

1.8_max_vs_ppe_vs_ppe_burnsed.jpg

It's hard to say for sure with a chassis dyno, but the Burns might've made a bit more up top. The collectors look the same on the inside, but Burns' has a much more pronounced neck:

burns_vs_ppe_collectors.jpg

I then shortened the PPE's runners by 2.75". They now measure ~27" (28.5, 28.9, 26.9, and 25.1). That helped:

ppe_burnsed.jpg

1.8_max_vs_burnsed_ppe_vs_cut_ppe.jpg

I then attach a 42" pipe to the collector. This made a big difference in mid-range, but didn't do much for the 5200-7400 range the car operates at:

1.8_max_vs_cut_ppe_vs_42ex_ppe.jpg

So I reasoned maybe the problem is post-collector exhaust length? PipeMax said the third harmonic is 34", so I started cutting down the pipe:

post_collector_lengths.jpg

The only material difference was in the 3-4,000 range, and it obviously liked the longer pipe more. There are differences elsewhere, but this dyno isn't super repeatable.

PipeMax recommends an 18" post-collector pipe, so I started cutting it down again from 24":

cut_ppe_42_vs_24_22_ex_lengths.jpg

Again the only material difference is the mid-range, so I decide to stop. We then do a leak-down test to verify the health of the motor (2-5% on all cylinders).

Here's the best PPE pull vs. the best 1.8 MAX pull:

best_ppe_vs_best_1.8_max.jpg

Any thoughts on what to do next? Burns' specs were obviously incorrect. I could more extensively modify the PPE header and try PipeMax's 20" spec, or I could (more easily) lengthen the 1.8 MAX header to 20". Given how far the PPE header was behind the 1.8 MAX at higher RPM, my inclination is that it wants more primary diameter than both Burns and PipeMax indicated. I'm not sure if motors are more tolerant of too much primary than too little, but it sure doesn't look like 1-3/4" would even be enough.

1-7/8" seems like a lot of primary for a motor making 40whp a hole though doesn't it?

Thanks for any help!

[maxracesoftware]

Any thoughts on what to do next? Burns' specs were obviously incorrect. I could more extensively modify the PPE header and try PipeMax's 20" spec, or I could (more easily) lengthen the 1.8 MAX header to 20". Given how far the PPE header was behind the 1.8 MAX at higher RPM, my inclination is that it wants more primary diameter than both Burns and PipeMax indicated. I'm not sure if motors are more tolerant of too much primary than too little, but it sure doesn't look like 1-3/4" would even be enough.

1-7/8" seems like a lot of primary for a motor making 40whp a hole though doesn't it?

Thanks for any help!

hi Grant , i just saw your Post here on SpeedTalk "after" i replied to your Email you sent me

please Upgrade to v4.70 PipeMax version from your v4.50 version

i noticed a few things that are incorrect in your PipeMax inputs
1]= you did not input actual Weather conditions at time of each Chassis Run
2]= you chose V-style Engine configuration ... you need to change this to Inline ... that is INLINE 4 Cylinder not V-style
3]= your Flowbench Numbers are a "mile high"...not possible ... please put in actual real Flow numbers
example : minimum PipeMax requirement is you must know at least your Intake Port Flow CFM at your Cam's max Valve Lift
and input that value into v4.70 version PipeMax ... at which that instant you input your Intake Flow Number
it will erase any VE% value and erase any Exhaust Flow number ... it will then use your actual Intake Port Flow number
to re-calculate both VE% and your Exhaust Flow Number
"IF" you have a real Exhaust Flow Number ... input that value ONLY after you first input your Intake Port Flow Number
then PipeMax will use both your real Intake and Exhaust Port Numbers !
4]= need to adjust "Intake System Volumetric Efficiency % PerCent Loss" value until PipeMax matches up
to what an Engine Dyno would show at the Flywheel instead of RWHP numbers
PipeMax uses Engine Dyno Flywheel HP ... so adjust your Chassis Dyno RWHP upwards to Flywheel HP
5]= you did not adjust both Intake and Exhaust System Port velocities to exactly matchup to both their Port Volume CC's
6]= your Engine is 4 Cyl DOHC ?? you need to change Cam Type in PipeMax
to either OverHead • Bucket - Direct Action ... or .... OverHead • Finger - Follower Arm
instead of a Solid Lifter Cam
7]= for all SOHC and DOHC Cam types you need to choose "Camshaft's Valve acceleration rate effect" to between Level 8 -to- 10
never lower than Level=8 ... change from your Level=4 to Level=8

like the old saying goes " Garbage In = Garbage Out"

there's more things you need to redo or enter into PipeMax v4.70
and it will get you even closer than my quick fix i made to your File
but i need a bunch a Data from you ... not Graphs .. but numbers !


i did a "quick fix" on your PipeMax file you emailed and i get
it would like or want a 1 7/8ths Header Tube OD ... just like you have

PipeMax calculates between 1.775 to 1.900 OD to maximum of 2.025" OD
so 1 7/8ths OD Tubes is great for Peak TQ + Mid-Range + Peak HP
and at 18.258" inches to 20.217

3rd Harmonic = 18.258 to 20.217 inches long ... highly recommended , best Torque and HP Curve
your 17" inches -vs- PipeMax's 18.258" ... pretty close !
maybe even closer if i knew exaclty what every part/value of your Engine Combo to input
what you missed in PipeMax

Calculated Exhaust Port Flow @28in.= 219.2691 -to- 234.8060 CFM @ 0.370078 Lift (no Flow Pipe)
User's Exhaust Port Flow input @28in.= 219.2691 CFM @ 0.320000 Valve Lift (no Flow Pipe)

Engine Application = Race Engine • Mid-Range Peak TQ • Hi RPM Peak HP

--- Primary Tube Specs : Race Header • Single Tube diameter size ---
Peak TQ Diameter Range = 1.775 -to- 1.900 Best Length = 18.258 -to- 20.217 inches
Best Mid-Range Diameter = 1.900 Best Length = 18.258 -to- 20.217 inches
Peak HP Diameter Range = 1.900 -to- 2.025 Best Length = 18.258 -to- 20.217 inches

--- Primary Tube Harmonics --- ( One-End-Closed Tube = Odd Numbered Harmonics )
1st Harmonic = 63.507 to 65.466 inches long ... typically never used ( too long to fit any Vehicle )
3rd Harmonic = 18.258 to 20.217 inches long ... highly recommended , best Torque and HP Curve
5th Harmonic = 9.208 to 11.167 inches long ... shortest recommended ( Shorty or very Hi-RPM Header )
7th Harmonic = 5.330 to 7.289 inches long ... shortest recommended ( Shorty, Hugger, or Log Style )
9th Harmonic = 3.175 to 5.134 inches long ... shortest recommended ( Log Style or Cast-Manifold )
11th Harmonic = 1.804 to 3.763 inches long ... shortest recommended ( Log Style or Cast-Manifold )

===============

just 1 more thing : i'd try and test out Collector lengths ...then next diameters .... your Engine should respond to that ??
but then again , your Cam's Overlap Period is negative -18.0 degrees ... need to see if engine will respond enough to Collector changes ??

[Grant]

Thanks! And sorry about sending you a junk file. I must've forgotten to save my latest (which had stuff like the correct flow bench numbers; or maybe that got auto-calced away somehow). It is an inline 4 16-valve DOHC, cam over bucket.

4]= need to adjust "Intake System Volumetric Efficiency % PerCent Loss" value until PipeMax matches up
to what an Engine Dyno would show at the Flywheel instead of RWHP numbers

Hmm, I took this to mean pressure loss across the intake system. Which is 0.8 kPa, so I set this to 0.8%. Was that not correct? I guess this is pressure loss at the port, which I can't measure with my MAP sensor.

My usual process is to enter everything I know, hit auto calc, then adjust VE % (which I have no way to measure directly) until the outputted power numbers match my estimate of engine power. I have access to a chassis but sadly not an engine dyno.

...though playing with it now, I see I was using the software wrong. If I let autocalc set VE to 137% and adjust intake efficiency loss, I get a 1-7/8" primary. If I leave intake efficiency loss low and adjust VE, the recommended primary size decreases. Power is the same either way.

This is strange though isn't it? Why would the header care if the losses were in the intake system vs. head (VE)? Changing intake efficiency loss does not seem at affect recommended primary size at all, at least on 4.50. I guess I'll wait until I can activate 4.70 before I play with this any more.

5]= you did not adjust both Intake and Exhaust System Port velocities to exactly matchup to both their Port Volume CC's

Yup, because I don't know the port CCs. And while these numbers affect predicted power, they don't (in my 4.50 file anyway) seem to affect recommended header specs. So I just left them at 285.

7]= for all SOHC and DOHC Cam types you need to choose "Camshaft's Valve acceleration rate effect" to between Level 8 -to- 10
never lower than Level=8 ... change from your Level=4 to Level=8

Ah thanks I had missed the DOHC / SOHC note.

just 1 more thing : i'd try and test out Collector lengths ...then next diameters .... your Engine should respond to that ??
but then again , your Cam's Overlap Period is negative -18.0 degrees ... need to see if engine will respond enough to Collector changes ??

It's got VVT on the intake cam. These figures assume 10 degrees advance, but we start at 25 degrees at 4500 and taper down to 0 at 7400.

Thanks again for all the help.

I'd also love to hear your take on the post-collector exhaust length tests.

[Grant]

While we're here I might as well throw in some intake manifold graphs too. This is the stock intake vs. the 1Goal:

stock_intake_cut_open.jpg

1goal.jpg

The OE short runners are activated when the butterfly opens, though we knocked the butterflies out of ours. Their average port length (with the OE aluminum extension) comes out to 16.2", PipeMax's exact 2nd harmonic for this engine. I don't know what the length of the longer runners is.

The 1Goal runners produce a port length of 9.5", but they're meant for a 2.5 head. They're a little big on the 2.0, with a ~1 mm lip from the runner to head. While this lip didn't keep the 1Goal from producing more peak power than the ported stocker, it definitely sucked overall.

stock_ported_vs_1goal.jpg

In the higher RPMs the 1Goal wanted about 10 more degrees of cam advance than the stock manifold.

We were thinking we might try to epoxy the 1Goal runners to match the 2.0 ports, but after looking at this graph decided it wasn't worth it. IMO the runners were just too short.

So I'm in the process of hacking up another stock manifold, to remove the longer runners completely and merge them with one big radiused opening per port. I haven't decided on length yet; PipeMax's recommended 3rd harmonic is only 1.3" longer than the 1Goal's runners, which were obviously way too short.

[digger]

It would be good to see the latest pipemax outputs and well these aligned with the better (short and fat runner) header.

i found the same thing regarding the impact on torque below peak torque rpm regarding the collector length when you have a given/fixed primary setup. No real penalty in being a lot longer than pipemax says or advantage in making it shorter (just hurts bottom end nil effect on topend) i settled on the 2nd harmonic after testing the 3rd and 4th as the second was best at every rpm from 1700 to 7000rpm.

I'm about to embark on a new primaries, have recommendations from burns, PM, EAPRO and my own ENGMOD4T design so been mulling over what to do to avoid going backwards which is not hard with exhaust so watching keenly.....

[Grant]

It would be good to see the latest pipemax outputs and well these aligned with the better (short and fat runner) header.

I just got 4.70 activated, and this is what it's giving me:

Code: Select all

Calculated Exhaust Port Flow   @28in.= 189.6675 -to- 203.1069 CFM @ 0.364791 Lift (no Flow Pipe)
User's Exhaust Port Flow input @28in.= 192.4163 CFM @ 0.320000 Valve Lift (no Flow Pipe)

Engine Application  =   Race Engine • Mid-Range Peak TQ • Hi RPM Peak HP

   --- Primary Tube Specs : Race Header  •  Single Tube diameter size ---
Peak TQ Diameter Range  = 1.674 -to- 1.799  Best Length = 19.217 -to- 21.176 inches
Best Mid-Range Diameter = 1.799  Best Length = 19.217 -to- 21.176 inches
Peak HP Diameter Range  = 1.799 -to- 1.924  Best Length = 19.217 -to- 21.176 inches

   --- Primary Tube Harmonics ---    ( One-End-Closed Tube = Odd Numbered Harmonics )
1st Harmonic = 65.984 to 67.944 inches long ... typically never used ( too long to fit any Vehicle )
3rd Harmonic = 19.217 to 21.176 inches long ... highly recommended , best Torque and HP Curve
5th Harmonic = 9.864 to 11.823 inches long ... shortest recommended ( Shorty or very Hi-RPM Header )
7th Harmonic = 5.855 to 7.814 inches long ... shortest recommended ( Shorty, Hugger, or Log Style )
9th Harmonic = 3.628 to 5.587 inches long ... shortest recommended ( Log Style or Cast-Manifold )
11th Harmonic = 2.211 to 4.170 inches long ... shortest recommended ( Log Style or Cast-Manifold )
------------------------------------------------------------------------------------------------------
   --- Collector Specs : Straight Tube Collector  •  or Straight with a slight Merge shape ---
Peak TQ Diameter Range  = 3.089 -to- 3.214  Best Length= 19.016 -or- 38.032 inches
Best Mid-Range Diameter = 3.214  Best Length= 19.016 -or- 38.032 inches
Peak HP Diameter Range  = 3.214 -to- 3.339  Best Length= 19.016 -or- 9.508 inches

H-Pipe Location= 19.016 or 9.508 inches     X-Pipe Location= 76.065 or 38.032 inches
( both H-Pipe and X-Pipe locations are measured from Primary Tube ends inside the Collector )

Dual-Exhaust System Diameter = 3.089 to 3.339 inches       Dual-Exhaust's each Muffler CFM = 195
Single-Exhaust System Diameter = 4.369 to 4.619 inches     Single-Exhaust's one Muffler CFM = 391

   --- Collector's Harmonics ---     ( Both-Ends-Open Tube = Odd and Even Numbered Harmonics )
1st Harmonic = 152.129 inches long ... longest recommended with Mufflers and TailPipes
2nd Harmonic = 76.065 inches long ... longest recommended with Mufflers and TailPipes
3rd Harmonic = 38.032 inches long ... greater Low RPM Torque -to- Peak Torque RPM
4th Harmonic = 19.016 inches long ... highly recommended , best Torque and HP Curve combination
5th Harmonic = 9.508 inches long ... reduced Peak Torque , higher RPM HP gains possible
6th Harmonic = 4.754 inches long ... reduced Low RPM Torque , even though Tuned Length

Best TQ + HP Tuned Collector Lengths= 4.754, 9.508, 19.016, 38.032, 76.065, 152.129 inches long
Worst TQ + HP Loss Collector Lengths= 7.131, 14.262, 28.524, 57.048, 114.097, 228.194 inches long

Collector definition: from the Primary Tube's ending inside the Collector -to- Atmospheric exit point
Note :  all Tube Outside Diameters are based-off your Header Tube Thickness choice's value
------------------------------------------------------------------------------------------------------
Bore=3.44488  Stroke=3.27165   121.97333706 Cubic Inches @ 6900 RPM  Intake System= 125.61065 VE%
Complete Intake System Flow    @28in.= 203.9273 -to- 218.3772 CFM @ 0.370000 Lift (11.00000 VE% Loss)
Cylinder Head Intake Port Flow @28in.= 225.0000 -to- 240.9430 CFM @ 0.370000 Lift (136.61065 VE%)
Cylinder Head's Exhaust Port CenterLine Length = 3.5000 inches
Target EGT= 1237.4 degrees F or 669.7 degrees C at end of 4 second 600 RPM/Sec Dyno accel. test
EGT Probe location = 0.750 to 1.000 inch from Header gasket flange at 12:00 O'Clock position
EGT Probe tip depth = 0.500 to 0.750 inch depth into Header Primary Tube
Speed of Sound = 2019.5 Feet per Second at 1.000 inch distance into Header Primary Tube
Header Collector Spear Length = 2.0000 inches        Exhaust/Intake Port Flow Ratio = 85.518 %
Exhaust System operating RPM Range from 4900 to 7400 RPM     Hertz frequency = 57.5 Hz at 6900 RPM
------------------------------------------------------------------------------------------------------
                                  Camshaft = OverHead  •  Bucket -  Direct Action
600 RPM/Sec Dyno Test             Level=6        Level=7        Level=8        Level=9    Piston FPM
Peak HorsePower    @  6900 RPM      171.0          173.2          175.4          177.6      3762.40
Peak Torque Lbs-Ft @  4900 RPM      141.3          143.0          146.1          147.9      2671.85
------------------------------------------------------------------------------------------------------
Fuel BTU=19000.0  Air/Fuel Ratio=13.200000  BSFC=0.597423  Mixture Distribution= 90.0 Quality= 90.0
Dyno HP Weather Correction Equation = 8•  SAE J607 (June1974) • STP • SuperFlow-FTQ • (Default)
HP Correction Factor= 1.000000000     Fuel Type= Gasoline • Race Gas • HP and Torque increase
Station Barometer=29.92000000  Air DegF=60.00  Vapor Pressure=0.000  Air Correction=1.00000000
Station Barometer NOAA=29.92885898   Pressure Altitude Feet= 1.2   Z•Elevation Feet= 0.0   
Density Altitude Feet=67.2    Relative Humidity % = 0.00    Dew Point DegF = -263.39
Virtual Temperature DegF = 60.00    Water Grains = 0.00        Wet Bulb DegF = 38.73

Code: Select all

Bore=3.44488  Stroke=3.27165   121.97333706 Cubic Inches @ 6900 RPM  Intake System= 125.61065 VE%
Complete Intake System Flow    @28in.= 203.9273 -to- 218.3772 CFM @ 0.370000 Lift (11.00000 VE% Loss)
Cylinder Head Intake Port Flow @28 inch =  225.0000 -to- 240.9430 CFM at 0.39027 Lift (136.61065 Ve%)

---- Induction System Tuned Lengths ---- ( * Open-End Tube = both Odd and Even Numbered Harmonics )
Harmonic  Total     Intake     Manifold    Air / Fuel Ratio = 13.20000:1   BSFC = 0.5974 LbsHour/HP
Wave     Induction  Port       Runner   ( Induction System operating RPM Range from 4900 to 7400 RPM )
Number   Length     Length     Length   ------ Description --------------------------------------------
1st     32.9485  =  3.7000  +  29.2485  typically Induction Length too long to fit or use effectively
2nd     16.4743  =  3.7000  +  12.7743  creates the highest Peak Torque, but may lose higher RPM HP
3rd     10.9828  =  3.7000  +   7.2828  ProStock, Comp Eliminator, etc. best Peak TQ and Peak HP Combo
4th      8.2371  =  3.7000  +   4.5371  Single-Plane Manifold, slightly less Torque than 3rd Harmonic
5th      6.5897  =  3.7000  +   2.8897  Peak Torque is substantially reduced, even though Tuned Length
Note: 1st and 2nd Harmonic Lengths sometimes create the highest Peak Torque, but may lose higher RPM HP
      the 3rd Harmonic Length typically creates the best overall combination of Peak Torque and Peak HP
      the 4th Harmonic's shorter Tuned Length allows for greater underneath Hood clearance

Note: all the above Induction System Tuned Lengths are based-off 0.500 inch Radius Entry Curve
      if your Radius Entry is less, the Power Curve will be shifted slightly to a lower RPM Range
      if your Radius Entry is greater, the Power Curve will be shifted slightly to a higher RPM Range
* Radius Entry Curve = Bellmouth Radius, Carb Entry Radius, Velocity Stack Radius, Plenum Entry Radius
_______________________________________________________________________________________________________

     ----- Intake Manifold Plenum Runner Entry Area ( * with 0.500 inch Radius Entry Curve ) -----
Minimum Recommended Entry Area = 2.400 to 2.700 Sq.Inch  ( minimum for 1 Carb Single-Plane Manifolds )
Average Recommended Entry Area = 2.759 Sq.Inch  ( good for Single-Plane or Tunnel Ram Manifolds )
Maximum Recommended Entry Area = 2.819 to 3.336 Sq.Inch  ( maximum for 1 Carb Single-Plane Manifolds )

Minimum Plenum Volume CC = 321.8 or CID = 19.6  ( typically for 1 Carb Single-Plane Manifold )
Single-Plane Manifold with 1 Carb Recommended Plenum Entry Area = 2.819 to 3.336 Sq.Inch

Maximum Plenum Volume CC = 1998.8  ( typically for Tunnel Ram Intake Manifold with Carbs, MFI, EFI )
Maximum Plenum Volume CID= 122.0  ( typically for Tunnel Ram Intake Manifold with Carbs, MFI, EFI )
Tunnel Ram Intakes with direct-line-of-sight Carb Bores Recommended Entry Area = 2.400 to 2.819 Sq.Inch
Tunnel Ram Intakes with poor-line-of-sight Carb Bores Recommended Entry Area = 2.819 to 3.336 Sq.Inch
_______________________________________________________________________________________________________

Induction System Tuned Length ( with Injector Stack Bellmouth or Radius Entry )  •  ( No Plenum Area )
  * definition :  from Head's Valve Seat Lap-Line -to- top of Injector Stack Bellmouth or Radius Entry

Induction System Tuned Length ( with IR = Independent Runner and Carb )  •  ( No Plenum Area )
  * definition :  from Head's Valve Seat Lap-Line -to- top of Carb Entry Area or Velocity Stack Radius

Induction System Tuned Length ( with Intake Manifold that has a Plenum Area )
  * definition :  from Head's Valve Seat Lap-Line -to- Intake Runner Entry Area inside Manifold Plenum

Using this file.

But there's a few things I need to figure out before I start cutting plastic or metal to fit its output:

What RPM is PipeMax optimizing for? Changing the peak torque RPM does not alter recommended intake or exhaust runner lengths, while changing peak hp RPM does. It does say "@ 6900 RPM" (my power peak) at the top of the induction calculator output... I don't want a boost at peak power; for my application and gearing torque at 6000 is much more important.

Why doesn't altering Intake System VE % Loss change header recommendations? Altering VE % does. You'd think a lower VE, regardless of where the losses come from, would equate to less exhaust flow and smaller primaries.

e.g., my current file recommends a 1.799-1.924" primary, and predicts 177.6 bhp. If I change the file to more realistic looking figures of 117% VE (still high) and 6% Intake System VE % Loss, I get 177.2 bhp and a 1.700-1.825" primary recommendation.

So I feel like I'm missing something obvious.

I'm about to embark on a new primaries, have recommendations from burns, PM, EAPRO and my own ENGMOD4T design so been mulling over what to do to avoid going backwards which is not hard with exhaust so watching keenly.....

Do the recommendations from those software packages differ significantly?

Many years ago we did a Burns header on an F22C1 engine and it turned out great. The primaries are something like 2-1/8" stepping to 2" though; not this 1-5/8" garbage. To my knowledge it made more power (236 dynojet SAE) than anyone has ever made on a stock motor. But their recommendation for the NC MZR was terrible.

Granted the NP01 is a spec racer (Nasa Prototype 1) so maybe they weren't after peak performance. Though the 1.8 MAX out-performs it everywhere.

[digger]

So I feel like I'm missing something obvious.

I'm about to embark on a new primaries, have recommendations from burns, PM, EAPRO and my own ENGMOD4T design so been mulling over what to do to avoid going backwards which is not hard with exhaust so watching keenly.....

Do the recommendations from those software packages differ significantly?

Noting that pipemax has several options and provides a range it agrees with Burns method very closely

Primary diameter and length

Burns: 15"@1.5 & 15"@1.625" total 30" length

PM: 14.3@1.474 & 14.3@ 1.599 = 28.6" length

ENGMOD4T: Suggest straight 1.500" is good enough no advantage to stepping to 1.625" and 26" is a slighty better overall top end power and no meanginful low to mid losses (i.e. a bit of slight criss crossing on curves)

EAPRO: 1.500" stepping to 1.625" is best with 26" is a slighty better overall top end power than 30" and no meanginful low to mid losses (i.e. a bit of slight criss crossing on curves)

[hoffman900]

1.500" will support that power level no problem, if built correctly. However, I would step it up within the first 10" or so.

For comparison, 950bhp 410ci Sprint Car engines use 1 7/8" off the head. That's 119hp/cyl.

[maxracesoftware]

Using this file.

But there's a few things I need to figure out before I start cutting plastic or metal to fit its output:

What RPM is PipeMax optimizing for? Changing the peak torque RPM does not alter recommended intake or exhaust runner lengths, while changing peak hp RPM does. It does say "@ 6900 RPM" (my power peak) at the top of the induction calculator output... I don't want a boost at peak power; for my application and gearing torque at 6000 is much more important.

Why doesn't altering Intake System VE % Loss change header recommendations? Altering VE % does. You'd think a lower VE, regardless of where the losses come from, would equate to less exhaust flow and smaller primaries.

e.g., my current file recommends a 1.799-1.924" primary, and predicts 177.6 bhp. If I change the file to more realistic looking figures of 117% VE (still high) and 6% Intake System VE % Loss, I get 177.2 bhp and a 1.700-1.825" primary recommendation.

So I feel like I'm missing something obvious.

still not actually using PipeMax correctly or to its fullest extent
i'm super busy in the Shop , and will re-renter all your new Data into PipeMax and Post a newer File + results
your Google File link above , i downloaded + looked at it , its still messed up !
maybe you're not saving the file before linking it ?? or your AntiVirus Software is not replacing old File with same File Name
maybe try saving file with new name or number ?? McAfee AntiVirus is worst for causing an old File not to be saved with new info .
If you have McAfee AntiVirus ? it could be the cause ??

[Grant]

still not actually using PipeMax correctly or to its fullest extent
i'm super busy in the Shop , and will re-renter all your new Data into PipeMax and Post a newer File + results
your Google File link above , i downloaded + looked at it , its still messed up !
maybe you're not saving the file before linking it ?? or your AntiVirus Software is not replacing old File with same File Name
maybe try saving file with new name or number ?? McAfee AntiVirus is worst for causing an old File not to be saved with new info .
If you have McAfee AntiVirus ? it could be the cause ??

Sorry, the problem was Google drive not syncing properly. I just fixed and tried it, and it did download my latest file.

[Grant]

The best plastic porting tool I found was a sharp aluminum (coarse) carbide bit. Before & after:

nc_intake.jpg

I opened it up to the start of the Y, which leaves a really big throat, which I hear is bad for harmonics. Total length to the start / end of the throat is 12.4 / 13.5"

[maxracesoftware]

Primary diameter and length

Burns: 15"@1.5 & 15"@1.625" total 30" length

PM: 14.3@1.474 & 14.3@ 1.599 = 28.6" length

ENGMOD4T: Suggest straight 1.500" is good enough no advantage to stepping to 1.625" and 26" is a slighty better overall top end power and no meanginful low to mid losses (i.e. a bit of slight criss crossing on curves)

EAPRO: 1.500" stepping to 1.625" is best with 26" is a slighty better overall top end power than 30" and no meanginful low to mid losses (i.e. a bit of slight criss crossing on curves)

PipeMax v4.70 software was closest to Grant's actual real-world results for both his Header and Intake system specs ! Look below at DATA/Pics

What RPM is PipeMax optimizing for? Changing the peak torque RPM does not alter recommended intake or exhaust runner lengths, while changing peak hp RPM does. It does say "@ 6900 RPM" (my power peak) at the top of the induction calculator output... I don't want a boost at peak power; for my application and gearing torque at 6000 is much more important.

PipeMax uses only Peak HP RPM input value ... then calculates a 2500 RPM Range with "a best inner strong 1400 to 1500 wide RPM band"
to create best specs for your Engine .... Example : your Engine's Peak HP RPM point = 7000 RPM
PipeMax then calculates the best specs for between 5000 RPM -to- 7500 RPM
with a strong inclination to calculate best inner TQ and HP Curve between 5500 RPM -to- 7000 RPM

you can't always use Peak TQ RPM point because that point is not consistent to Peak HP RPM point
it varies way too much ...example : a Racer could make his best Peak HP at 7000 RPM , but his best Peak TQ could vary widly in relationship to Peak HP RPM point ,
it could be as close as 6500 RPM relative to 7000 Peak HP point because his Cam Duration + Header + Intake system lengths and diameters are wrong
... so PipeMax does not use Peak TQ RPM value for certain calculations .... instead its setup to calculate a much better RPM Range specs for you !


here's Zip file of PipeMax simulation of your engine i could come up with

nc_pipemax2_MAX.zip

 

here's a few Pics of instructions + data :

GrantMainTAB.jpg

GrantMainTABinstructions.jpg

GrantExhaustSpecs.jpg

GrantExhaustRPMSpecs.jpg

GrantInductionSpecs.jpg

GrantWeatherSpecs.jpg

[hoffman900]

1.500" will support that power level no problem, if built correctly. However, I would step it up within the first 10" or so.

For comparison, 950bhp 410ci Sprint Car engines use 1 7/8" off the head. That's 119hp/cyl.

Also as a reference, Calvin Elston starts with 1.625” primaries on 5L Ford Coyote engines, making in excess of 750bhp, or about 93hp/cyl.

[maxracesoftware]

1.500" will support that power level no problem, if built correctly. However, I would step it up within the first 10" or so.

For comparison, 950bhp 410ci Sprint Car engines use 1 7/8" off the head. That's 119hp/cyl.

Also as a reference, Calvin Elston starts with 1.625” primaries on 5L Ford Coyote engines, making in excess of 750bhp, or about 93hp/cyl.

that does not work at all for all Engine combinations
relatively speaking example : a NHRA Record setting low VE% and low CompRatio Pontiac Stocker will use a 2.125" OD Tube , sometimes 2.250" OD
making "half" the HP of the 950bhp 410ci Sprint Car engines use 1 7/8" off the head. That's 119hp/cyl.

[hoffman900]

Well, I’ve see Calvin pull off 1 3/8” on a low VE, non-crossflow 4 banger making about 58hp/cyl

It’s a whole engine thing. What can be done in the engine is dictated by what a talented header builder can get away with, and vice versa. Nothing is done in isolation!