Datsun R 16 head porting advice?

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Daryl S.
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Datsun R 16 head porting advice?

Post by Daryl S. » Tue Nov 27, 2018 10:30 pm

A previous head which had some welding done on the combustion chamber turned porous, leaking into the water jacket, so I'm working on a new to me head. The intake ports seem to be pretty good, but the exhaust ports look to need work?
20181125_140304.jpg
20181125_140248.jpg
Stock Valve sizes are 42mm Intake and 32mm exhaust (8.7mm stem, dual springs), I am considering 44mm and 34mm with 7mm stems, beehives.
Flow on the head just removed was 190 cfm @ 28" on the intake and ~125 cfm exhaust.
I'd like to at least match the intake, but get the exhaust higher, 130 - 135 if possible.

2065 cc 4 cyl pushrod engine, trying for 165+ HP, basically sunny weather street sportscar. 7000 rpm max.

Thanks
Pictures below are from the previously worked 'leaky' head....
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Last edited by Daryl S. on Tue Nov 27, 2018 11:23 pm, edited 1 time in total.

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Re: Datsun R 16 head porting advice?

Post by Daryl S. » Tue Nov 27, 2018 11:07 pm

Intake Port Cropped Resized.jpg
Intake Port Side Cropped Resized .jpg
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Re: Datsun R 16 head porting advice?

Post by Daryl S. » Tue Nov 27, 2018 11:19 pm

Exhaust Port Top Ruler Resized.jpg
Exhaust Port Side Resized.jpg
Exhaust Port Angle Resize.jpg
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Re: Datsun R 16 head porting advice?

Post by Carnut1 » Wed Nov 28, 2018 6:05 am

http://speedtalk.com/forum/viewtopic.php?f=1&t=51342
Take a look at my VW thread. They have similar prts but the VW ports are straighter. I would think about keeping the port volume as low as possible to stock to keep torque in a usable range. Thanks, Charlie
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Re: Datsun R 16 head porting advice?

Post by hoffman900 » Wed Nov 28, 2018 7:09 am

It’s a L20, but close enough:

http://performanceforums.com/forums/sho ... atsun-head

I’m sure Tony will be along.

Also, those heads are similar to the Triumph / Volvo heads, which Erland has experience in, especially the exhaust ports.
-Bob

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Re: Datsun R 16 head porting advice?

Post by Carnut1 » Wed Nov 28, 2018 5:44 pm

hoffman900 wrote:
Wed Nov 28, 2018 7:09 am
It’s a L20, but close enough:

http://performanceforums.com/forums/sho ... atsun-head

I’m sure Tony will be along.

Also, those heads are similar to the Triumph / Volvo heads, which Erland has experience in, especially the exhaust ports.
Bob, thanks for that link, Tony's work is top notch!
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Re: Datsun R 16 head porting advice?

Post by mag2555 » Thu Nov 29, 2018 7:29 am

You realize what your saying here?
Out of a 126 cid motor your looking to make 1.3 hp per cid to attain 165 hp!?

It's funny the way the numbers work out on this one as Intake cfm wise @28" you need to average 165 cfm per cylinder by my math to hit the target HP number.

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Re: Datsun R 16 head porting advice?

Post by hoffman900 » Thu Nov 29, 2018 8:14 am

mag2555 wrote:
Thu Nov 29, 2018 7:29 am
You realize what your saying here?
Out of a 126 cid motor your looking to make 1.3 hp per cid to attain 165 hp!?

It's funny the way the numbers work out on this one as Intake cfm wise @28" you need to average 165 cfm per cylinder by my math to hit the target HP number.
A L16 is capable of nearly 200bhp in race trim. A L20 can be north of 230bhp.

Hell the little 5 port BMC A-Series can make nearly 2hp/ci in race trim.
-Bob

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Re: Datsun R 16 head porting advice?

Post by induction apprentice » Thu Nov 29, 2018 8:46 am

I have ported a few L 16 and L 20 heads.
I also tried welding in chambers and roof of port around spring perch. I was devistated after many attepts at welding went bad. i weld lots of aluminum heads. But those are funny buggers? They love to fracture and off gas like no other. So avoid welding if possible I would say. They dont look anything like a volvo b20b head or ports. But I do agree Erland is one guy that could help you. They are very good heads. But thin casting as the cutaway shows. So stay conservitive. The exhaust is mostly bowl work. Grind out the guid bos and slope the exh bowl roof the way it naturally wants. Youll see.

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Re: Datsun R 16 head porting advice?

Post by mag2555 » Thu Nov 29, 2018 9:11 am

Where did I post / say that level of power could not be done my friend?
Also please note that the OP has stated he is talking about a "fun street car" , NOT a 2 hp per cid full out race motor as you are talking about!

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Re: Datsun R 16 head porting advice?

Post by Daryl S. » Thu Nov 29, 2018 9:24 pm

Thanks for the links. Read through them and found this one too...

Very similar to the Volvo...
http://speedtalk.com/forum/viewtopic.ph ... 8&start=30

And the Triumph TR4...
http://www.tr3a.info/FAQ_heads.htm (bottom of page)

Though I'm not sure the Datsun exhaust is as bad....?

The stock head/stock 42 mm intake valve flows about 165 cfm @28", 32 mm exhaust flows right around 100 cfm, both at .500"

Question.... If the intake already flows the required air for the power target, what advantage is there to making it flow 190 - 200 cfm?
Guessing since there is a minimal port size increase, it has to be increased velocity, and therefore increased cylinder filling...

The port walls seem to be pretty consistent around .250" thick, thinking I should be good removing up to .125"? (parts of exhaust port...)

Will clean up head and get some more pictures up this weekend.

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Re: Datsun R 16 head porting advice?

Post by Xnke » Mon Dec 03, 2018 6:04 am

R16 and L16 are two different engines-Not the same head/ports/anything.

Look at U20 heads if you are looking for similar ports and how they're ported, the R16 and U20 use very similar cylinder heads, although they're not the same either.

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