Nissan L-Series Cylinder Head Flow Bench Testing and Development

[MONZTER]

I've decided to build a detailed thread to document L-Series cylinder head flow testing and the results. Like many aspects of these engines, it's sometimes hard to know what to believe or how to interpret what you see and read. Test setup, equipment, testing methods, and just straight-up BS can all contribute to the confusion.

I don't sell a product or service and have nothing to gain from the results I post, so my goal is to keep the testing unbiased and as consistent and repeatable as possible.

Feel free to comment or criticize as I move through this. I'm happy for any input.

 

First up is the equipment.

 

I have a SuperFlow 600 converted to run the digital FlowCom directly to my laptop where I use PortFlow analyzer from Performance trends.

 

This software sets up the test and aids in the data logging and reporting.  It also compensates for Altitude, Barometric pressure, ect.  So no math or reading of the old school manometers.  Its super accurate and very repeatable.

 

 

I built a L-Series specific test stand and replaceable cylinder bores to test the common sizes, 84mm - 240z , 86.5mm 280z, and 89mm - Big Bore.  This has a considerable effect to the max flow due to bore shrouding, so its important to test on the correct size.  This is the first place numbers can get "offset"  If some guy is flow testing a Z head on his 4" Chevy bore, you bet the numbers will look good.  More on this later.

 

These bores are made of nylon and seal to the test stand with an o-ring.  However any leakage can still occur, so the software takes a zero measurement first, and this leakage is then subtracted out automatically

 

 

Next up is calibration - the bench should be calibrated on a regular basis to check for issues.  You do this by bolting the supplied test plate that is matched to the machine and simply flowing it.

 

Here you can see the plate bolted on, it has calibration flow percentages written on it to compare

 

 

 

Ans this is the screen on the laptop, you can see the bench is within .1 percent calibration for the intake and exact for the exhaust

 

  

 

 

Ill flow and document the heads I have as well as some I will borrow from friends.  Some will be stock, some will be modified to various states.

 

Ill also do some test to help point out important details.  So stay tuned

 

Thanks - monZter

Edited September 6 by MONZTER

[MONZTER]

The first head to document will be an old E88 from my 72.  I used this head a long time ago worth 40DCOE triple Webbers.  In typical fashion long long ago I did my best to do what I thought was right.  I blended the seats to match the bowls with a grinder, and port matched the head to the intake, opening up the port about 1" in from the entrance to blend the new opening (not good). other than that, stock valves and chambers

 

So lets flow it.  Hoping to borrow a stock E88 to compare later.

 

Some pics for referance

 

   

 

   

 

Here are the head Specs

 

 

Cylinder 2 Intake with 84mm Bore

 

 

And Cylinder #2 Exhaust with 84mm Bore

 

 

I then switched out the bore to 86.5mm and tested again, here is a comparison chart of the effect of only a larger bore

 

 

 

 

 

Sorry the image is hard to read I need to figure out how to upload better resolution pics, but you can download the PowerPoint below

E88_Flow_Bench_Comparison_Cyl2_84mm_vs_86.5mm_FIXED (1).pptx

Edited September 8 by MONZTER

[DuffyMahoney]

Super cool, thank you for posting.

[calZ]

This has the potential to be one of the best threads in this site's history. It would be awesome to end up with complete database of head flow for the different combos. 

[DuffyMahoney]

My E31

[jeffer949]

Very cool. Are you getting a pamz head?  I forget if that was you or not.  Be interesting to see how it does. One thing ive always been curious on is the difference between the runner size on the exhaist on a n42 p90. The middle two are much wider than the outer 4. Picture is of an n42 and a p90 im rebuilding.   

 

Im starting a cylinder head rebuilding buisness and while im not going after the high performance market its amazing the difference a valve job can make. We have come along way since the 30/45/60 valve job. I have seat cutters with 6 or more angles and radius exhaust and so o. Im not flowing heads but thankfully there are guys online doing so. Its amazing the flow they get by a little tweaking hear and there

[DuffyMahoney]

No PAMS head for me.  I am pretty proud to own one of Andy Kazanis's heads.  I believe he and a few others think the E31 flows the best of any of the heads, with enough effort.