Great ork! It's amazing to me how many people out there don't do any combuston Chamber work. Chamber work and a good flow correction port work is where all the power comes from!

15 or so years ago I was modifying the predecessor to this head, the 2.3L Ford PZEV Focus head and the Mazda 2.3 MZR head found in the Mazda 3 and 6. The end ports on these heads pinch in slightly and the center ports are fairly straight. I found these engines to be capable of making good usable power, 270-300+hp depending on compression ratio and cam specs, and using proper induction and exhaust systems. We had heads with strong low lift numbers flowing 330+CFM at .600” using 38.5mm valves and we were managing better than 90% I/E flow ratio up to .300”. Chamber work was critical, the valve job was critical, and the particular castings we were using were critical to that success. Cosworth made a run of parts for these engines around the same time and I managed to get booted out of their PRI booth when I stopped by to say hi, because I used one of their manifolds and produced more power than they said it would support with a few modifications. I’m glad these engines are still seeing interest they’re good engines. But it looks like the direct injection head is down on potential a little bit from the port injection version.

not sure what escorts have a 2.3, not here in the states anyhow. the ZX2 was the last of the escorts here and they have the 2.0l Zetec. Id like to see you go over a Zetec head!

Woooo! I can breathe again... Thanks for getting to the 4 valve videos, I've been holding my breath since you announced they were coming. I have a set of northstar heads on my bench waiting also. My 1st 4v build. Love your books and the powertec series, have learned greatly. Please don't take too long getting the polyquad episode out... I'll be holding my breath again!

I think the most trick combustion chamber on a 4v head has got to be the old Honda rfvc singles 250cc-650cc engines. The rocker system is kinda convoluted as the rockers have to come from the 4 corners. Really neat set up. Likely a big market for ported built heads for the xr600r/650L heads as millions of the bikes are out running on the trails and roads.

Great video! I've owned a 2006 mazda 3 (not Mazdaspeed) since 2009. After 312,000 miles the engine has an issue and im about to rebuild it. I belive i can achieve at least 85-90% of what youve just shown in this video. Im no novice, Ive been building cars since 1974. I do NOT want a high strung race motor (been there with Datsuns SSS and Toyotas) but with more emphasis on Torque with a mild increase in HP.

Most of the numbers and terms in this video are way over my head 😮 no pun intended 😅

I'm hooked and I can't stop watching your content, Mr. Vizard. I absolutely enjoy the technical deep dive you deliver and what a breath of fresh air it is. As a slightly better than amateur head porter, I almost exclusively work on Subaru heads. I do a lot of flow bench testing but my software is like banging two rocks together compared to what I see you using. On full out builds, I tend to make very deep bowl pockets, removing almost all of the valve guide support inside the intake runner. Coupled with other more conventional porting techniques you outline in other videos and in your books, I'm able to achieve respectable flow numbers and the chassis dyno always backs this up with many miles of customer smiles. However, all of the reading I've done to date says to shape an aerodynamic fin around the valve guide instead of grinding it completely off. In practice I have found this to be more tedious and less effective than just grinding it straight off on these heads. I understand this may not be viable for some head designs due to compromising the support for the valve stem. Give me some thoughts if you could, I'd really appreciate it. I've not yet been able to crack 300 CFM on one of these heads yet but, I believe it's possible for a more experienced and skilled porter. Thanks for what you are doing, it is so greatly appreciated.

Agreed. Polyquad information is on pages 118-119 of How to Port & Flow Test Cylinder Heads. "...When attention to port size, an increase in flow, and the generation of swirl... produced more power with less boost."

Great stuff. My only criticism is that in the die-grinding section, the difference between before and after wasn't completely clear for each mod. Really looking forward to the Poly-Quad episode. You mentioned that the port energy density of the exhaust port still wasn't particularly good after the mods, even compared to good 2V heads. Would it be worthwhile doing an episode that explains PED in detail, and compares various heads so that people can get a better idea of what's good and bad in both an absolute sense, and for particular engine types?

Thanks very much, I was hoping for episodes of 4 valves per cylinder stuff

Thank you for sharing your knowledge, looking forward to more on the Mazda MRZ series.

Yessss!!!! Finally some 4 valve per cylinder videos!!!! Can’t wait for the polyquad!!!!

Tremendous effort invested to bring forth this video. Very high caliber and super generous offering of the important tidbits none of which seem to have gone overlooked. Stupendous production gents. Will be looking forward to a copy of the magnificent IOP development computer program. Beautiful. Thank you.

Thank you for how to hotrod a mini. You shaped my life. ❤

Hi DV, thanks for taking the time to produce these videos. Can you do more videos on four valve heads?

That was fantastic! Thank you so much for your time.

Excellent work and explanation. Such a shame you can’t get intelligent feedback on the book review. We are spoilt to have the advantage of your experience

Thanks for the 4-valve info! 👍

Thanks so much, sir. Even if the video you put about an hour, ill gladly watch it till the end. every video you made have been knowledgeble, and inspiring to me.

Thank you for doing a 4-valve!

Great! Fantastic! I was waiting 4 valve tech. Thanks you very much for sharing. I want apply your advices on my 2004 Mini Cooper. Again, many thanks and cheers from Italy

I'd like to swap a modern head onto a older Chevy i6 250/292, a vortec4.2 maybe, or Honda j-3.5L heads, or just some LS heads , I saw LS heads on a 300 Ford, The VTEC would be cool, build a cool possibly dual runner length using motorcycle carbs , modified, with large bowl with possibly a holes pump and squirters, near 50mm carb per cylinder, a 44-48 mm probably, with a aluminum sheet and tube intake, with a 6-1 bagore the carbs, going to a large cone filter, or maybe a turbo, join the intake runners with 1" I.D. tube with about 4-5" runners, with a good size maybe use 8 carbs , two for low rpm use working similar to the old quadrajet carbs, about 30-38mm feeding into 3cylindrs through a longer 3-1 tubes that feed into the runners similar to EFI injectors only from the bottom of the port, to put the air flow in the top of the intake ports, this would aci like a dual runner intake, short and large for top end power, it's complex and could not work that great, but it would be a fun project, especially a 250cid with modern pistons , and a lightened crank, and atleast 5140 rods, ARP main studs, and about 3 bar from the turbo, upto about 6k rpm (5600-5800 rpm, maybe 6k,) work the heads, and get the chambers to fit the cylinders without alot of offset of the bores/chambers, port work, matching to the intake, 6-2-1 turbo header, maybe a performance valve job, possibly larger valves, 3.5 to 4.1 liters isn't that much leap, the v6 may rev slightly higher, although it's not really a high performance engine, a couple mm larger could help , ( 2-3mm) the VTEC with possibly reground cams, awesome, get about 10:1 with 3bar boost, should make tons of power for 6 old cylinders!! Haha crazy, maybe try a similar setup with Honda heads on a SBC engine, make V8 heads from a handful of V6 heads, the J series heads seem to work well, the engines make tons of power with boost, it's Japan's LS engine, along with the K series , it wouldn't be possible with k heads I don't think, the bore spacing is a bit tight, it sounds like if I could weld aluminum, and could machine parts, I'd drive myself insane building (attempting to build crazy stuff). It would basically be a Honda v,8 I think I'd stay under 350 cid, probably build a 327 or similar displacement, Have a awesome day

Glad to see the 4v stuff even if it isn't my favorite compression ignition version.

Thanks David, that is what I needed to see.

Another great video David.

This was another good video. Nice to see work on a 4 valve head. Crazy compression ratio compared to Cosworth YB.

I saw 2.3 and four valve head and got all excited thinking you were going to do the lima motor with the volvo head. Oh well, still a great video.

Love the 4 valve videos

Thanks David! Been waiting very patiently for a 4 valve video. Can't wait for the polyquad video. What are modern F1 port angles? Why are the flow figures measured with fixed pressure rather than floating? I was under the impression floating better replicates what happens in an actual engine.

Thank you for sharing your knowledge.

I love this! Now I just need to figure out how to poly quad an old 4.6l B head.

dude fantastic videos.... Thank you!!!

There was some very professional engine builder who know a lot how to tune 4 cyl 16valves race engines, like Brian Hart, David Wood, Terry Hoyle and Italian Aurelio Lambredi.

1980’s Thunderbird 2.3 Turbo She needs a Polyquad Head:)

For anyone who knows the Duratec/MZR and was a bit perplexed which head this actually is, it's from a 2012+ USDM Focus 2.0L TiVCT GDI engine. I've heard it wasn't available across the pond.

Thanks! David, very interesting, I have a 2.3 here, that I would like to turbocharge.

I have recently purchased how to build horsepower and how to port heads and read a couple of reviews like this, people complained information wasn't in there when it was. I figure they either didn't read the whole books - possible, or they want to be spoon fed with diagrams and plans they can copy without doing any thinking themselves - most likely.

🇦🇬 Greetings David, from Antigua & Barbuda. Another excellent video as usual. Would you please add a Toyota 3SGTE and Honda K20 porting videos to your portfolio. 🙇🏾‍♂️

Great video! Make a video on k20 silender head also!

Great videos David, love them all and was waiting to see a 4 valve head porting. Have you done any on the Honda B18C and the K20Z3...

awesome info, looking forward to more 4 valve cylinder head, not to long ago I did a 4 valve Mazda BP04 head, from a puny 95cfm avg to 238cfm avg. how ever my main focus was immediate velocity...in real time the cams open close faster then a couple turns of a screw. I could have gotten more CFM if i wanted to take the loss in port velocity. like most Mazda designs the roof is the key factor. flat and a nice contoured radius, pay attention to the sidewall contour stay away the velocity falls pretty fast here, from my experience. after was all said and done. 10.5:1 comp, OEM cams (0.339" max lift) @24psi 420whp 407ft-lbs torque@6000rpms on E85

Correction it’s only a 2V head. 1980’s 2.3 Ford :) My mistake

If that DI head is anything like the earlier Duratec heads... the exhaust ports definitely need to be remade. SBD welded up the sides and made oval ports on the turbo rally motors they built.

Good day to you David. I have watched a few of you videos over the past few days and found them most informative. Will you be making a follow up to this video? Also, did I hear you say that you'll be working on a Mustang Ecoboost cylinder head at some point? I am hoping a book titled Port and Flow test arrives today so I can continue my education. Regards Karl

I take it you meant an EcoBoost engine. Some of those have the exhaust manifold integral in the head which is not optimal. Some reports of head gasket and block cracking causing coolant consumption. Mazda 2.3 bore is 3.445" with a 3.7" stroke. The 3.504" bore is the 2.5 engine which also has a longer stroke which is 3.94" or 100mm.

Your website is broken and I can't find the camshaft or head programs anywhere. At the same time, I wouldn't really know how to use the latter, mostly because I don't know how to get the flow numbers and port area and such from a given head. Lastly, I'd probably get upset because I wouldn't be able to find a base engine to work on with the right combination of displacement, head design, flow numbers/shapes for combustion efficiency, cylinder count, weight, block strength for boost, transmission compatibility, and aftermarket support, then I'd say "I just need to have my own 1-off engine made" then scoff at the price of that and just be mad at the injustice of being a car guy. Though that last part is a massive assumption and I'm sure there's SOME engine out there that will work for me and has enough potential for my goals.

Love your show. 22:35 22:45

I have a question, now that we are comparing flow numbers between a V8 5.0L ish 2 valve cylinder head and a 2.3 4valve cylinder head, how is cylinder filling, it is not the same the volume of a V8 cylinder then the one from a 4 cylinder, in the meaning that maybe the flow numbers don't need to be that high as cylinder filling is accomplish with less flow on a 4 cyl as the volume is smaller, I understand that flow energy will help to ram in maybe a little extra of the full volume of the cylinder, but will flow reversal eventually not happen at a point when full = full at atmospheric pressure, and as RPM increaces then there is less time to fill adeacuatly and reversal is more likely to happen or is that not the case ?

Best 🚀🔥🚀

Hi David, This is just related to brain injury. Check out the story on Joe Namath reversing Chronic traumatic encephalopathy by using isobaric oxygen chambers. We want you around and healthy.

When I have done a motor or two I have taken all the sharp edges out of the combustion chamber and chamfered them out to the head gasket line to remove any 90 degree internal corners between bore and under side of head (like as with a Hemi head). Any thoughts?

Could you use smoke to check air flow on test bench? Maybe a sensor placed in various spots in the port during flow testing ?

Would the Polyquad layout provide the same benefits on a DOHC diesel engine as well?

David, how much of this can be utilized for a semi truck engine? Specifically a Caterpillar C12 engine. The combustion chamber is actually part of the piston dome. Where the 4 valves are in the head, is totally flat, from one end to the other.

Any ideas for making 6degree oldsmobile shortside radii work?

Can you please tell me how much height offset Mazda combustion chamber has in mm... between intake valves and exhaust valves?

I was trying to see the before and after flow numbers for this head? I can't see it in the data provided.

Hi There. When you mean lowering the exhaust valve. Do you mean lower when you are facing from the combustion chamber or from the valve train?

Great Video! Rotax built the engines for the last version of Buell motorcycles. They opened one intake valve slightly before the other to initiate swirl. The engines got exalent fuel mileage. Has anyone tried that on an 4 valve car engine?

Could you do a video on the k20a2 or k24a2 head.

You need to do a cyote head

David, are these the same heads used on Ford 4 cyl engines from about 2013 on? I know that the basic engine design was developed by Mazda and Ford and variants are used by them along with Volvo.

Hello Mr. Vizard. I have a Mercedes Wagon Resto Mod project. It is a 95 320 TE with a six cylinder but will receive a M119 5.0 liter engine from the 95’ SL500. It makes only 65hp per liter. Or 325hp total. I am looking for at least 80hp/liter or 400hp. Do you think porting the heads with stock camshaft would be enough or would I have to also upgrade the camshafts. Unfortunately at the moment, nobody offers Camshafts for this engine as far as I know. I would be open to having some made if that is possible as well.

hey David i have a toyota 3sge head which i want to get ported iam currently building it to be a turbo motor could i send it to you to have your tuch done to it

The ford intech 4v head had separated ports with different sizing for a “Polly quad” type swirl. It definitely sucked compared to tumble design of a duratec or coyote.

Been a while since you talked about your Poly Quad idea. There are many cams where the same flow idea is now ground right into the camshaft itself. Many years ago I saw a similar idea used on Sonny Lennard's Big block Chevy's with custom ground cams and different diameter intake valves to equal out flow and swirl across the head as well. Sonny's ideas set a lot of records, just as yours have as well David. It is the little things that matter, lol. Sometimes they make a huge difference as well. Great minds set records. That Mazda head is in excellent hands for sure. If it runs as good as your other poly heads (Ryan's for example) that will be a vicious little Mazda, lol. My STI boxer makes 698 whp @ 30ish psi. Heads are not poly'd, but many of your ideas were used to shape the ports and chambers. Thank you for sharing your knowledge, I have followed your knowledge for years.

Wish you had , given valve to troath data for what you did there ,

EcoBoost, not Ecotec, which is a chevy motor I think.

Hello DV, I'm building a competition 1UZ and I'm interested in your IOP program. Is it available for purchase?

But will it bolt to a small block Chevrolet or Ford???

"Intake valve lift as L/D"? How do we correlate this to inches of lift in .100"?

Comparable to modern motorcycle heads.

Is there a chance that you will be doing anything with Harley M-8 four valve heads? I would be willing to send you a set if you're interested.

Review done by a competing book author?

Hey DV. I think your efficiency figures are skewed by valve diameters much larger than reality in your program. The NA 2.0/2.3/2.5 L engines had 35/30 mm valves and the Ecoboost uses smaller valves yet. You used 41/36 mm in the program, which I'd definitely like to see stuffed in an 89mm bore!

I have your book that covers the poly quad on 4 valve and who ever wrote that review doesn't know how to read

I've had that book for years and looked at the polyquad design many times, how could anyone be so dumb to completely miss it? Maybe they don't actually read and didn't look at the pictures?

God , what's that awful hissing sound in the background? It's very distracting.

This video is a blessing 🙏🏼

David i believe this is l engine head which are very similiar on the 2.0,2.3 versions which some had vvti and some didn't like the ford ranger