Datsun R 16 head porting advice?

[BLSTIC]

Relieving the block to match the combustion chamber has other implications.

If you are only relieving it 1-2mm but going deep you're creating a fairly large amount of crevice volume beside the piston that won't burn easily. That's part of the recipe for detonation if there's fuel or oil in there.

Do tell about the headers. A "port tongue" for filling in the port floor might be a good way to get a decent transition to tiny primary pipe. Long radius small pipe still flows pretty good, and by the time you've got appropriate steps at each section/join the final choke can be pretty small without actually being restrictive. At 165hp you definitely want to be under 2" at the final choke.

[Daryl S.]

"If you are only relieving it 1-2mm but going deep you're creating a fairly large amount of crevice volume beside the piston that won't burn easily. "
Had not considered the crevice volume and potential problems. Actually I was thinking of just grinding it at about a 45* angle, and 3 - 4 mm deep. Just enough so it's not a dead straight shelf....??
The U20 engine block has a fairly substantial cut for the intake valve, tho I don't know how big...

Header is a modified, ceramic coated, off the shelf 4-1. Now 4-2-1, with 1 1/2" primaries, 1 5/8" secondary to 2" . Had this done years ago before I'd learned (on SpeedTalk) about 'chokes' or a/r chambers....Have considered making the secondaries longer, but, that would require a larger hole through the frame of the car, which I am not prepared to do just now...If that comes up in the future I will consider a 'choke'. Port Tongue - I have read of this many times here and have never seen a picture. I assume this would have to be done at the building stage of the header not added after?
Thanks for the tips.

R16 4-2-1 Header resize.jpg

R16 4-2-1 Header3 resize.jpg

On the engine with EFI plenum manifold. Crank trigger can be seen at the front of the engine.

R20 EFI 4-2-1 resize.jpg

[blown265]

Gday mate

I relieve the block as a normal part of building this particular engine, who's hemi chamber overhangs the block near the intake valve.

In the attatched pics, the cut is just visible.
It goes out to the gasket line, and down the cylinder to the top ring location . I stop cutting 40th short of both.
I do it at an empty block stage- not sure I'd be comfortable with an assembled short block.

Ive not quantified the inprovement, but it seems intuitive to blend the transition into the cylinder. Even with basic porting, we do it with the same style of step into bowl from the valve angle cuts.

Regards
Paulie

(ignore thr text in the pics- thats just record keeping)

[mag2555]

Daryl please contact me with your email address.

[BLSTIC]

"If you are only relieving it 1-2mm but going deep you're creating a fairly large amount of crevice volume beside the piston that won't burn easily. "
Had not considered the crevice volume and potential problems. Actually I was thinking of just grinding it at about a 45* angle, and 3 - 4 mm deep. Just enough so it's not a dead straight shelf....??
The U20 engine block has a fairly substantial cut for the intake valve, tho I don't know how big...

Header is a modified, ceramic coated, off the shelf 4-1. Now 4-2-1, with 1 1/2" primaries, 1 5/8" secondary to 2" . Had this done years ago before I'd learned (on SpeedTalk) about 'chokes' or a/r chambers....Have considered making the secondaries longer, but, that would require a larger hole through the frame of the car, which I am not prepared to do just now...If that comes up in the future I will consider a 'choke'. Port Tongue - I have read of this many times here and have never seen a picture. I assume this would have to be done at the building stage of the header not added after?
Thanks for the tips.
R16 4-2-1 Header resize.jpg
R16 4-2-1 Header3 resize.jpg

On the engine with EFI plenum manifold. Crank trigger can be seen at the front of the engine.
R20 EFI 4-2-1 resize.jpg

I mean just for a test you could probably drop that final choke down to 1 3/4, it might help a little mid-range for not much effort

But 1 1/2" off the head is probably good for 55-65hp/cyl (based on a spreadsheet I made from Calvin Elston's numbers with a couple of assumptions thrown in, so you know, grain of salt and all that) if you've got good transitions. Which brought me to around 1 3/8 off the head for your 165hp*.

Port plates sold at https://www.mpgheads.com/c8-c9-d0ve-port-plates/

dove_in_head.jpg

So it's mainly used if the port floor is too low and the ideal header size is notably smaller than the opening (which is pretty common). You could use a similar thing to start the "shrinking" transition inside the port (rather than trying to fix some particular airflow problem like the pictured ones supposedly help with), giving you a smoother transition and smaller port volume (less energy wasted expanding into a port rather than getting the gas down the pipe)

*Calvin Elston actually made a header that was 1 3/8 off the head for a 195 WHEEL horsepower 4 cylinder. It was a unique situation though, with an AR chamber in each primary and a "double step" increase in size (to 1 5/8) at the chambers. That engine had major reversion issues. Had...

[Daryl S.]

"Ive not quantified the improvement, but it seems intuitive to blend the transition into the cylinder."
Thanks Paulie, that was my thinking as well....

BLSTIC,
I've had the PipeMax program for a few years now, and between that program and following different header and porting threads on here I'm aware of several shortcomings of the current header (bend likely too tight off the head, secondarie 90* bend a bit tight and pipes a bit short...slightly oversized primary). It's a tight engine compartment, and the frame gets in the way. I would love to make a new header, but I'm afraid this is it for now.
I will keep in mind about the choke, and the A/R chamber, as those don't seem too hard to implement without starting over. Choke placed at the final collector, then I'd have to leave about 16-18 inches to put in an A/R chamber (goes through the frame at that point).....

Also, after I started this thread I upped the anti on the power. My target is now 170 to 180 hp. I know I can get the intake flow required for that power level, the exhaust however could be a challenge....on the upside tho, apparently Rebello in California is getting 180 - 185+ hp from these engines at 6500-6800 rpm, so....there is that.
Some thing that I've never understood with these engines, considering others were getting 2 hp/sq. in. with BMC 5 and 7 port heads, why have racers with the R16 seem to struggle to get 1.5 hp/sq. in. with its 8 port head?

Thanks for posting the picture of the header 'tongue'. Since the port on the R16/H20 head has a straight, flat floor, something like that might not be all that hard to implement.....

[Chris_Hamilton]

....on the upside tho, apparently Rebello in California is getting 180 - 185+ hp from these engines at 6500-6800 rpm, so....there is that.

A 150 HP engine on Rebello's dyno would show 200+ HP . You can't believe anything they state as to HP. It's all marketing. They were claiming an L6 engine combo they sell made 300+ HP with almost no porting of the head. Same guys who never sonic check L28 blocks before boring them to 89 or 90 mm (from 86) when it's known that L28 blocks have a core shift issue.

Guys doing cutting edge stuff with Datsuns are in Australia and Japan. Les Collins Racing, is one. Speed Talk member Tony Knight knows his way around them as well.

[Daryl S.]

"A 150 HP engine on Rebello's dyno would show 200+ HP ."
And I thought they were one of the respectable ones....

Onward....
The intake port has this odd shape on the outward curve.....Would it be worthwhile to add material (JB Weld?) to smooth that out as shown in this photo?

IMG_0143.jpeg

Here's another view without the marking...

Intake Port Cropped Resized.jpg

[hoffman900]

....on the upside tho, apparently Rebello in California is getting 180 - 185+ hp from these engines at 6500-6800 rpm, so....there is that.

A 150 HP engine on Rebello's dyno would show 200+ HP . You can't believe anything they state as to HP. It's all marketing. They were claiming an L6 engine combo they sell made 300+ HP with almost no porting of the head. Same guys who never sonic check L28 blocks before boring them to 89 or 90 mm (from 86) when it's known that L28 blocks have a core shift issue.

Guys doing cutting edge stuff with Datsuns are in Australia and Japan. Les Collins Racing, is one. Speed Talk member Tony Knight knows his way around them as well.

Aaron Kelly would be the guy I talk to in the US. He’s a great builder / cylinder head porter.

+1 to Rebello’s dyno.

[Daryl S.]

"A 150 HP engine on Rebello's dyno would show 200+ HP . You can't believe anything they state as to HP. It's all marketing."

"+1 to Rebello’s dyno."

....Making me think perhaps I should be downgrading my power aspirations.....on the other hand, BMC, Volvo, Triumph engines seem to be making power in this range with similar ports....??
Well, I am committed on this project, already have a ton of time and money into it and not about to quit.

I found an old printout from a flow test done years ago on a stock head. This is with a single cut for the 45* seat, and seats which hang over into the airflow by close to/over 1mm in places. I had one head ported which I was told the intake flowed 190 cfm @ .500" lift. He wasn't happy with the exhaust (no #s), but it provided a good power upgrade on an 1800 cc engine.

Stock R16 Head Flow Test picture - resized.jpg

38mm motorcycle throttle bodies and custom intake built for this. One of the reasons for these ITBs was to get a straighter run at the ports. Centre to centre on these is 72mm vs the standard DCOE of 90mm.....I'm an electrician, not a welder, fabricator, or engineer....my weird ideas come from reading the threads on here as well as a number of books and other websites (megasquirt threads....). I was initially against ITBs because of the complexity, but, unexplainably relented and am giving it a shot. It's really to prove a point that these engines can be built for decent power. Although I am not winning the argument...yet....

R16-Honda 38mm ITBs resize.jpg

Short block is built. Cam is .325 lobe lift, 225* intake, 235* exhaust duration, 112* LSA, 1.55:1 roller rockers.

[hoffman900]

Aaron Kelly is getting about 185bhp from a full prep, SCCA GT spec A13. Mike Jones does cams for Aaron as well.

The R16 has to have a SIR, correct? Unless you’re doing vintage now.

[Daryl S.]

"The R16 has to have a SIR, correct?"
Sorry Bob, don't know what you mean by an SIR? Not Racing, a street engine, no rules, just a budget....

Contact info for Aaron Kelly or AVP heads? Google search isn't getting anything to do with porting.....

I sent Mike Jones a cam years ago....don't know if he still has it, but, I never heard back from him.

Thanks

[Daryl S.]

I also have the valves.
1.7" Intake and 1.37" Exhaust. 7mm stems and PAC 1223 beehive springs.

[Daryl S.]

A quick, rough drawing of a side view of the exhaust port as it looks stock in red, and intended reshape dashed green. At the very most there is about 1/8" material for the short side turn, some have almost no material above the valve seat.
The port is 1.1" wide and 1.25" tall for a CSA of 1.377 sq in. If I follow recommended port size from PipeMax, I need to add about .250" to the port floor to get a 1.1 sq in port CSA....

Exhaust Port Side Resized.jpg

Port Bias?
This rough drawing shows the ports curved shape, each away from the cylinder centre. Does this provide a port bias or is there more to do in the bowl area?

Port Curve resize.jpg

[BLSTIC]

Well that exhaust floor is going to have approximately zero flow on it, ever...

Is there anything you can do in the chamber to encourage flow to enter on the long side? With that kind of port it looks like anything you try make enter the short side will disrupt flow. Suppose you could test this on the bench pretty easily