Porting Porn

Fix_Until_Broke said:

So to pose a question - how do we evaluate what something like dimples or waves (or porting, or cams, etc) does to overall engine performance? What is gained, what is lost, etc?

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I suppose, it'd be expensive and time consuming to to use 3 different heads(stock, ported & ported with dimples) on the same engine to do multiple runs on the same dyno. It'd mean the head would be the main variable during the runs, if we can agree to drop minute changes in atmosphere humidity, pressure, temperature and etc.
This wouldn't give us everything, but it'd at least show the %age of power increase over stock. It would give us a great jumping off point though.

CFM is only part of the story. Like this guy says at 16:50, there is no such thing as the best cylinder head/port job.

https://youtu.be/VsmbbuSq9m0?t=1009

Houpty GT said:

CFM is only part of the story. Like this guy says at 16:50, there is no such thing as the best cylinder head/port job.

https://youtu.be/VsmbbuSq9m0?t=1009

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Very well stated in my opinion - What is best?

You know how tell a 450hp engine is really working? You DRIVE IT. When it breaks, you FIX IT. When something breaks, it is the weak link. Keep fixing and go again...and again...and again. I doubt that 1) you will get 450bhp and if you are able to, 2) it will ever be sustainable for any length of time. Which is fine... just not our goal.

All the charts, graphs and dynos, are fine. The real test... FIELD TEST. What I keep seeing is the 'experts' come out and say what is wrong but won't say what is right. When I make a VERY OBVIOUS post of the bottleneck, there is absolutely no response. How obvious must it be?

We have been porting heads for the TDI's for about 8 years. We have cams designed by our cam expert for the ALH, AHU and PD motors; all produced around the same time. (Then it got even busier). They were never meant to take maximum advantage of the cylinder head, maximum valve height or any other maximum. We have thousands of cams and hundreds of ported heads on the road in working engines. We have had very good results, with virtually no negative reactions. Can they all be operating under a placebo effect? Not in your life... You know what they say: You can't fool all of the people all of the time.

There is a complaint made against us from a dubious post, made by copy/ pasting to create a whole new thread, "PD Cams"...
http://forums.tdiclub.com/showthread.php?t=338977&highlight=PD+Cams T

The comment was, "I wish I never bought a Franko6 cam..." I think the intended purpose of this thread was to tarnish my reputation. I believe the thread was closed because it backfired for it's intended purpose. I didn't have time to respond, so those who already had my cams/porting work spoke for me.

About a year later, from the most famous of TDIClub threads, "What did you do to your car Today?" Page 987, post #14,804: The same guy who complained spoke up again.

dieselpower04

"Filled up 13.1 gallons after doing 714 miles back and forth to work (115 miles, one way) = 54.5 mpg."

That is my SAME Stage II PD cam, now up against a MikeW tune. And the funny thing is, after getting the car running so well, he still didn't think the cam had anything to do with how the car ran; just the tune saved him.

I am not trying to build monster engines. I will leave that to people like you, Andy2. Our major point is fuel economy and longevity. I am getting that done. However, I can't 'dyno' fuel economy. I can't flow bench longevity. And as to Newlite, agreed, keeping port air speed up contradicts maximum port, maximum valve height or total CFM. I get that. And as Tom Nelson says in that video, I will paraphrase, "What perfect?" What is your goal you attempting to accomplish? Can I ever relate to "..They were out partying and I was still getting greasy."

The very first thing we do is unshroud the valve porting below the seat and take it from there. We eliminate the most obvious bottleneck as that is undeniably a benefit. We do not often agree that big 'ol valves are going to be the ticket, as there is the cracking issue and there is also on the intake valves, an issue of shrouding against the cylinder wall... hard to compensate for.

And we do sell what we call snake oil. We have used LiquiMoly Purge as a tonic for weak, clogged or otherwise unbalance injectors as a 'first attempt' to inexpensively repair them. It so often works, we are not against promoting the stuff. But that doesn't stop us calling it 'snake oil'.

Don't be looking for us to ever do dimpling. The slower air speed in a TDI will never take advantage of it.

TDI entry / middle part of port is pretty big to begin with and there will not be big gains working on this area.
I use tubes all the time with some "max effort" SBC engines where bolts go to water in block and oil at top.. its easier to make them seal with tubes, but tubes can occassionally leak.
not something I'd personally aim with TDI 8v head.

Dimpling.. I have been using coarce surfaces on carbureted gasoline engines with too big of a port for the engine combination, to get fuel better back to the air stream.
With fuel injection engines there does not seem to be difference and I have always had best luck with smooth finish at flow bench.

Mid lift flow importance is not actually that simple.. or even true.
Most flow is required when engine (piston) demand is biggest, at around 72deg ATDC.
Low lift flow can be good when camshaft / valve is too small (like in case of 8v TDI) but increased low lift flow will hurt TQ under torque peak and usually gains are seen at max peak HP RPM and higher RPMS.

Perfect cross section area for intake side is when biggest amount of air mass can be trapped to cylinder.
In general with big runner you want to use earlier IVC and maby more overlap to assist flow to get in to speed and with small runner you want later IVC to make use of air mass inertia and shut the valve just when reverse flow has started.
Then with DI diesels you must have also swirl, or it wont mix well with air and hardly collected air is used only partially and diesel will burn a much slower.. without swirl, more air wont translate to HP.
Dig the swirl away you there will be nice gains IN FLOW BENCH! =)

Using bigger valves does not remove any material from cylinder head it self, so it does not increase cracking tendency.
Actually ported heads seem to crack less often, I believe its because of less heat load for the head?

I think HP per boost pressure is a good measure of engine efficiency.
I have seen good 1.9TDI combinations making ~104hp per bar of pressure.
1atm + 2.2bar aditional = 333hp.

Thank you MarkP this gives use a lot to think about

Had a moment to give some reflection. The comments about leaving the exhaust port 'match' alone and the reversion problem is something I need to address. We have seen the mismatch of the exhaust runners to be as much as .275" per side smaller then the exhaust manifold port. The exhaust manifold is usually very close in dimension to the exhaust gasket. The smaller diameter of the exhaust runner compared to the exhaust gasket is too large a difference for me to ignore. But when I say 'port match', I am figuring in for the reversion. There is a small step between the smaller exhaust port opening and the exhaust manifold. I would have to refer to this as a reversion step.

Reversion is not an uncommon occurrence. There is a debate where exactly the reversion step should be placed, but since there is no better solution generally available, the placement it is a matter of convenience. In this case, the point where the exhaust runner and exhaust manifold meet. The same issue happens in the intake and we use the same method.

On another note, some have made comment about the finish we made for the runners. Shaping a runner, it's easier to apply 'to good' a finish. But the point that was not recognized, you can see the shape of the port much better if it is smooth. It's easy enough to 'rough it up', for better flow.

We also have decided it is time to get into the ceramics for pistons, cylinder head and exhaust porting. The latest versions are showing spectacular results. In the case of exhaust porting, where we find the advantage of ceramics to be the most value, it wouldn't matter what finish was applied to the port, as the coating will basically smooth that all out. Not much to be done. When discussing this issue with a very knowledgeable porting wizard we know, his comment is that the advantage of the heat carried through the port is worth more than the reduction is whatever flow rate is lost by 'too smooth a port'.

Not long ago, a porting expert was able to gain an additional couple of cfm for Sprint cars that nobody else could find. When asked what he did, he told them he used a 36 grit sanding drum for the finish texture. Now it seems, everybody with a Sprint car is doing it. We realize there is much of this that is incremental and there are some things that apply across the spectrum with porting.

In the last year or so, I was asked to endorse a product sold on the TDIClub. Only problem was, I have never seen the product, don't know how it works, don't know IF it works and they wanted me to buy it, install it and test it. When I didn't want to buy the product, the request was then, to endorse a product that I never saw, understood or tested. Of course, my answer was "NO". Personally, I would never make the same request to anybody.

I am not asking anybody to endorse what we do. Really, I am busy doing what we do and believe we do it well. I find that the largest noise is made by competitors and those who don't know what we do and complain about things that they don't understand or recognize. There are even those who denigrate another porter's work shown in Youtube, when some of the techniques he uses are generally accepted techniques. In the end, the question is effectiveness. I think the final analysis; is there substantial improvement? Never saw the results from the guy in Georgia. I can show what we do is effective.

The post here is with intent to improve the learning curve for porting. I think that is happening. As for the guy from Georgia, the resin impregnated water jacket trick to cure the vexing problem of porosity is excellent information. Without this post, I don't know if I ever would have seen that useful information. There is always room for improvement and I am always open to find improvements.

Heck Frank, I have two of your re-done ALH cylinder heads in service at this time. Both had mild port jobs done. I have a third waiting to ship out (eventually) for the same re-build and port. Recently got back from a 1250 mile trip running a 6 spd. transmission and up and down the freeway hills mostly in 6th at 80mph. Figured the mileage and got 52mpg! Now this car has a lot of mods and still gets great mileage and power. I suspect the head is an integral part of what makes this work so well. Anyway, thanks for your work and care.

Thank you! It's a pleasure to do business with you.

Any CR porting?

Wanted to ask this myself. Gonna do some porting on my CR head and i dont want to ruin the so called swirl.

I just measured valve seat angle, 45 degrees on both intake and exhaust.
What is the best angle for flow?

Macradiators.com said:

Wanted to ask this myself. Gonna do some porting on my CR head and i dont want to ruin the so called swirl.

I just measured valve seat angle, 45 degrees on both intake and exhaust.
What is the best angle for flow?

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read up on how valve jobs are done

your basic three angle valve job will be 30 45 and 60 just to set the proper contact area, then you can throat with a die grinder, valve deshrouding isn't really a thing on these until you sink your valves into the head

practice on a junk head, or you'll learn on your good one

Since the issue of the DieselGate, and not knowing what will be left in the US to work with, we have not taken steps to work toward a solution for either the cam profile or the porting for Common Rail heads.

This isn't a question of unshrouding, but a matter of modifying swirl from a cylinder head that has impelled swirl by restriction of 1 each of the intake and exhaust. This is tricky business and my opinion is that messing with it too much will drastically impact fuel economy. If your goal is massive HP, go for broke and gut the thing. Swirl is much less of an issue if economy is not important.