Nissan L-Series Cylinder Head Flow Bench Testing and Development

[MONZTER]

For round ports like ours, these do alright, find the smallest location, and then measure this telescoping gauge with calipers  ,  But remember diameter is different than area.  With the diameter you can calculate area with an easy online calculator if you forget how to do it.

 

[MONZTER]

Hi Duffy, here's some more of the info I promised.

 

Looking at your port size and flow numbers, I think your engine is pretty well suited to a 7,000 RPM power peak.

 

Going with a much larger cam might shift the powerband higher without gaining much peak HP, especially given the head's airflow limitations. For a street-driven car, I'd favor average horsepower over chasing a higher RPM peak.

 

I built my cam calculator around Kameari's range of cam profiles, with a dropdown for Street, Sport, Track, or Race to help determine the intended powerband.

 

I originally had your engine set to Sport, which recommends the Kameari 70A at 241° @ 1 mm, or 232° @ .050" . Switching to Track changes the recommendation to the 73A at 253° @ 1 mm, or 244° @ .050".

 

Your Bonk cam is 240° @ .050", putting it right between those two recommendations. So far, I'd say you made a pretty good cam choice.

 

here is the cam recommendation tab in my calculator

cam.pdf

 

 

 

 

 

Next I'll show you the EAP simulated dyno curves for the different cams so you can see how they compare.

 

I loaded all the engine parameters into my analysis program to compare the cams  Here are the results.  Of course some assumptions as usual, as I did not put the Bonk cam on my cam stand to actually measure its profile, so it is a educated guess where the Kameari cams are documented.  As expected a little more top end a little less midrange but all in a good range for what you are building

 

 

As a final note, in the calculator the simulation assumes ideal conditions, and these are engine numbers at the flywheel.  so I would be very surprised to see these actual number, especially on a chassis dyno.  What's important is the shape of the plot and getting the power where you want it and how you want it.

 

This last one is my best guess of what your car should be around on a chassis dyno, 12% drivetrain loss and some reduction for real world conditions

 

 

 

[DuffyMahoney]

13 hours ago, MONZTER said:

Hi Duffy, here's some more of the info I promised.

 

Looking at your port size and flow numbers, I think your engine is pretty well suited to a 7,000 RPM power peak.

 

Going with a much larger cam might shift the powerband higher without gaining much peak HP, especially given the head's airflow limitations. For a street-driven car, I'd favor average horsepower over chasing a higher RPM peak.

CompareCars

 

 

I built my cam calculator around Kameari's range of cam profiles, with a dropdown for Street, Sport, Track, or Race to help determine the intended powerband.

 

I originally had your engine set to Sport, which recommends the Kameari 70A at 241° @ 1 mm, or 232° @ .050" . Switching to Track changes the recommendation to the 73A at 253° @ 1 mm, or 244° @ .050".

 

Your Bonk cam is 240° @ .050", putting it right between those two recommendations. So far, I'd say you made a pretty good cam choice.

 

here is the cam recommendation tab in my calculator

cam.pdf 287.14 kB · 1 download

 

 

 

 

 

Next I'll show you the EAP simulated dyno curves for the different cams so you can see how they compare.

 

I loaded all the engine parameters into my analysis program to compare the cams  Here are the results.  Of course some assumptions as usual, as I did not put the Bonk cam on my cam stand to actually measure its profile, so it is a educated guess where the Kameari cams are documented.  As expected a little more top end a little less midrange but all in a good range for what you are building

 

 

As a final note, in the calculator the simulation assumes ideal conditions, and these are engine numbers at the flywheel.  so I would be very surprised to see these actual number, especially on a chassis dyno.  What's important is the shape of the plot and getting the power where you want it and how you want it.

 

This last one is my best guess of what your car should be around on a chassis dyno, 12% drivetrain loss and some reduction for real world conditions

CompareCars

 

 

 

 

Gosh 240hp would be pretty bad for the amount of time put into my motor:)

 

I guess time will tell

[MONZTER]

I don't think so, it's going to be a wonderful street / track car.  To make 300hpb you would have a good looking dyno graph and a pain in the ass car to drive.  From the math, all your parts are really well matched to your head and it's purpose.  When will it be running?  Again, it's just a dyno simulation, so we will see

[DuffyMahoney]

On 11/10/2026 at 10:31 PM, MONZTER said:

I don't think so, it's going to be a wonderful street / track car.  To make 300hpb you would have a good looking dyno graph and a pain in the ass car to drive.  From the math, all your parts are really well matched to your head and it's purpose.  When will it be running?  Again, it's just a dyno simulation, so we will see

CompareCars

 

I have been chasing software bugs all week, basically going from a bare bones Haltech Elite 750 to their fancy R3'

 

Hopefully it starts today