Cylinder Head Flow Tested

[L_RAO]

Hi everyone,

I had the chance to pick up a junk 3.0 cylinder head and had it flow tested in various conditions. My sequence of testing went:

1. stock (with 35 mm intake valves)
2. stock sized valves + valve job
3. mild port job
4. with +1 mm intake valves + new valve job
5. with combustion chamber work
6. with +2 mm intake valves + new valve job

Testing was done on a Superflow 1000 at 28 inches of water, and we tested from 0.050" lift up to 0.600" of lift in 0.050" increments. Upsized valves were Manley units.

My data will be kept proprietary for now, but I can tell you that the best configuration the 3.0 heads likes is #4. I am choosing to ignore the data from 0.500 to 0.600" of lift since there aren't any cams that come close to offering that much lift.


Data from #4
0.050: 55.0% over stock
0.100: 18.4% over stock
0.150: 12.9% over stock
0.200: 3.4% over stock
0.250: 0.9% over stock
0.300: No change
0.350: 3.0% over stock
0.400: 8.8% over stock
0.450: 13.5% over stock

Take home message: The 3.0 cylinder heads really like a +1 mm intake valve and a good valve job.


A thank you goes out to connectorman who was going to scrap that head. Instead, it was used in the name of research.

 

[naaman]

Awesome! Now we just need to get the right cam grind. This is great stuff, L_RAO. Please keep up the great work!

 

[d_prada1]

i have been following your threads and i must say :encouragement:.

Have you clayed this motor? I would like to know the P2V clearance.

I figure some 36mm valves and a lift of .455 .470 would pair up rather nice.

 

[L_RAO]

i have been following your threads and i must say :encouragement:.

Have you clayed this motor? I would like to know the P2V clearance.

I figure some 36mm valves and a lift of .455 .470 would pair up rather nice.

No, the testing was done on a spare/junk cylinder head.

I would also like to know the P2V as well as the V2V clearance.

 

[dablackgoku1234]

the best configuration the 3.0 heads likes is #4

Just to be clear, #4 includes the mild port job?

 

[L_RAO]

Yes, but the gains from #2 to #3 (the port job itself) were minimal.

Just to be clear, #4 includes the mild port job?

 

[dablackgoku1234]

Were you able to benchmark your values with other engine heads just to see how well the NSX heads really flow?

 

[L_RAO]

Yes, they outflow the Honda B-series, but not by much.

The K-series and F-series (S2000, not Accord LOL) both outflow the C-series, and since those motors are used a lot in all sorts of competitive racing, there are variants that really put out some nice numbers.

That being said, the head I had tested put out some really impressive numbers at 0.500 to 0.600" lift.

If I had some Toda Cs and 12+ compression, I would definitely want/need the 36 mm valve with port work and valve job.

Were you able to benchmark your values with other engine heads just to see how well the NSX heads really flow?

 

[SOURCE 1]

Thanks for doing this! I just pulled heads off of an extra engine Saturday to send out and have this done. Now I don't have to. Awesome!

 

[jond]

Good stuff! Thanks!

 

[GhettoRacer]

nice work. you are dedicated to NA l_rao. you must have done a lot of research already. in the past were there people who had their heads ported professionally by reputable shops?

 

[docjohn]

comptech included a mild extrude hone port polish on thier iem package

 

[greenberet]

comptech included a mild extrude hone port polish on thier iem package

I believe Comptech hand-ported the cylinder heads.

From a 1990's Comptech NSX catalog: "NSX enthusiasts looking to improve overall engine performance should consider the Comptech High-Velocity Cylinder Head option, a component of our highly successful Internal Engine Modification Package ("IEM Package"), the results of which feature an increase of up to 100hp! In developing the High-Velocity Cylinder Head, our race engineers have worked hard to gain additional top-end power without sacrificing low and mid-range torque. We accomplished this by keeping the port as small as possible and removing material in selected areas, with painstaking attention being given to the valve and seat pocket area. Our special design and engineering allows for the port volume to remain small, while increasing air velocity. The results produce a harmonious balance for street and track applications. If you desire more power for racing purposes, check with us regarding our Full Race Porting option (excellent for track use, but low-end drivability is sacrificed)."

When I had Comptech carry out work on my engine, I spoke with them about their "High Performance Intake Manifold". Again from their catalog: "Simply send us your original factory intake manifold, less all hoses, electronics, etc. We will then port and polish the manifold to our exacting specifications, utilizing the same equipment used to prepare our race team vehicles." They recommended, if I didn’t mind the extra cost, that I send my intake manifold to Extrude Hone instead since that yielded an even better result.

Based on that, I believe Comptech hand-ported the cylinder heads and did not have them Extrude Honed.

 

[docjohn]

..............ahhhh .....so thats why i paid so much hand rubbed by artisans...:wink:

 

[greenberet]

A hand rub is cheap but having a head hand rubbed by a professional can get expensive!

in the past were there people who had their heads ported professionally by reputable shops?

I don't know how many people had Comptech port their NSX's cylinder heads but docjohn and I are two of them.

 

[liftnot]

I believe Comptech hand-ported the cylinder heads.

From a 1990's Comptech NSX catalog: "NSX enthusiasts looking to improve overall engine performance should consider the Comptech High-Velocity Cylinder Head option, a component of our highly successful Internal Engine Modification Package ("IEM Package"),

do you remember who you talked to? Don Erb? who was their engine builder? Shad must know something about this.

 

[docjohn]

john ......his last name sounded like serimaly....something like that...now this was over 10 years ago.

 

[greenberet]

Your best bet is to give Shad a call. It's been 19 years since I had Comptech port my cylinder heads, modify my airbox, etc. I spoke with Jonsie regarding their high-volume oil pump and I also noted that I spoke with Don, Bob, Curt, and Chris, but I didn't note who ported the cylinder heads or who their engine builder was.

 

[liftnot]

Thx. thats all I needed to know. I'll track them down.

 

[scammy]

I just had Port Flow do my spare heads they enlarged the intake valve by 1mm to the 3.2 spec installed brass guides and gave them a tidy up look real nice in the photos havent got them back yet as all the new valves and valve train is off being WPC treated

 

[liftnot]

The owner of PF - Tom Fujita, we used to work together at Nissan. He knows what he is doing.

 

[GhettoRacer]

what kind of power did the full comptech catalog tuned C30A put down?

 

[docjohn]

I was at 298 rwhp on a 90 degree day on a dynojet....but no pre mod power level to compare.

 

[greenberet]

what kind of power did the full comptech catalog tuned C30A put down?

In the May 1994 issue of Car and Driver, there was an article titled "NSX-cellent Project" in which a full Comptech catalog-tuned, street-driven, C30A-engined NSX was described as putting out 358 crank hp at 8000 rpm. See here: http://www.nsxprime.com/forum/attachment.php?attachmentid=41740&d=1208447790. I assume the data was from Comptech, not independently measured, however.

 

[scammy]

The owner of PF - Tom Fujita, we used to work together at Nissan. He knows what he is doing.

yeah I found them very good to deal with, I attached some photos so you guys can check out their work