Why an engine makes more power off a burr finish

[900HP]

Here is a quote from Larry Meaux in the other thread:

the very 1st Head i did , was just entire Intake Port up to bottom of Valve Job
and it gained HP and shifted point of Peak HP upwards around 100 or 200 RPM ??
i'd have to go back and look at Dyno sheet.

at that time ,i just chalked up the HP and RPM gain to the CSA being a little larger
not sure if the texture was making all the gains ?

thru the years, i've had Cyl Heads come thru my Shop from Customers
that had around 1/2" to 1" rough texture just under Valve Job,
some were from Reher•Morrison , and hearing thru the grapevine ... it was worth 6-10 HP,
so i just took it a step further by experimenting doing entire intake port .

from that 1st Head texture tests... i started doing the Chambers,
and it was a little more HP + lower BSFCs most times ,
then started doing complete Intake Manifold + Plenum
and still a little more HP.....then complete exhaust ports.

after around 10 or 12 different engines, sizes, and Brands all gaining HP,
the engine with the very 1st Heads i did only the Intake Ports,
we decided to grind the rough texture everywhere in that BBC engine too,
back on the Dyno, it was a total of 20-25 more HP than it ever made before
from when it was just a 60-Grit finish everywhere -to- ending up being fully textured everywhere in final tests.

to date ... probably i'm around 25+ engines so far with rough texture, everyone gained HP,
around 5 or 6 engines with very rough texture,
was supposed to Dyno test 714cid Ford engine this Thursday with new very rough texture everywhere
but Builder decided to lower CompRatio 2 points with little less new Cam ,
so the new Dyno tests data won't count or be any use as to texture effects.

[900HP]

Another quote from Larry Meaux:

Theories ?? ... What really counts is , Did it run faster down the DragStrip ???

So far its 100% gains on my end ... every Engine i've done the Texturing to has made
more HP and has Run faster down the Dragstrip !

[Unkl Ian]

Here is a quote from Larry Meaux in the other thread:

So who is going to be the first idiot to tell Larry he is wrong ?

[Unkl Ian]

"If your results don't agree with your theory, get a new theory."

Grumpy Jenkins

[900HP]

"If your results don't agree with your theory, get a new theory."

Grumpy Jenkins

LOL. Also from the other thread:




GARY C wrote:


On the flow bench, basically no flow gains I can measure from roughing up the entire heads/manifold surfaces. On the dyno and down the dragstrip, we consistently see more HP and quicker ET/MPH times. In 2010 Jeff Colletta won the NMCA NPS Championship with the rough carbide finish everywhere in the intake and exhaust ports, chambers, and intake manifold.

140, please read the OP's entire post and then contact Larry and let him know that it is only for crappy heads so he doesn't wast any more time setting records with this out dated theory.

cspeier wrote: Yep, we just reset our own A/ND record last weekend. One month ago it was 6.89, 2 weeks ago went to 6.81 and now today it's 6.77..

I better smooth those ports so the other guys are competitive!

[cv67]

Half tempted to try this on my single plane all it costs is time. Would be interesting to see if it behaved any differently one direction or the other

[900HP]

Half tempted to try this on my single plane all it costs is time. Would be interesting to see if it behaved any differently one direction or the other

OK, my last quote from Larry Meaux and the other thread, I promise I'll stop

actually , A-B-A was Smooth -to- Rough then back to Smooth again
Rough texture made 17 Peak RWHP gains on EFI L92 headed engine
then lost -17 RWHP when put back to relatively smoothed out 60-Grit finish

[F1Fever]

I have been a proponent of the rough finish for years and have an interesting theory as to why.

I think it's rather obvious the advantages of the rough finish in regards to keeping the fuel off the walls and in suspension for a cooler more homogenous mixture. We can most all agree on that I believe.

But I also believe that primarily happens at lower rpms. At mid to higher rpms a secondary advantage (my theory) comes into play. As the air speed begins to increase a boundary layer is formed which essentially makes the port act as though it's smaller increasing velocity throughout the mid rpm ranges. At higher rpms the boundary layer is "compressed" so to speak, it's "harder" and closer to the walls letting the port act closer to it's full size. This boundary layer also acts as a "lubricant" for the flowing air much like an air hockey table uses air as a "lubricant" for the puck.

[140Air]

Did you read it?

Yes, I did read it.

"“A properly designed rough surface, contrary to our intuition, can reduce skin-friction drag,”
noted John Kim, a professor in the mechanical and aerospace engineering department at UCLA"


Did you ever think someone might be smarter than you ?
Maybe you are right, and the Sun still revolves around the Earth.

Maybe you read it and thought it applied to this discussion in which case you did not understand it.

[140Air]

It started in the early days of aerodynamics and the text books have the results and the best funded, most knowledgeable engine designers and racers do NOT use grossly textured ports. Hotrodders have argued about it for at least 45 years. If it offered a provable advantage EVERYBODY would use it by now

As has been mentioned maybe 20 times in this thread, the texture is application specific. Even Nick Ferri, who has to be included in your above group says its application specific. If it was not application specific everybody would be using the same texture by now. But, it is. So, we're not.

Yes, I read that. Unfortunately, a claim of validity in special circumstances weakens a claim. I won't try to go into why this is true, but the strongest claims are those with the widest application and the most robust effect, where robust means the effect is big and/or consistent. Larry Meaux' interview claimed the effect was on the order of 1.5% power and zero % flow. As for consistency, many, many people have investigated texturing and if it was even a small, but consistent effect, EVERYBODY designing for maximum power would have been using it from the beginning.

[F1Fever]

If my theory is correct, and I do believe it is, that means it's very application specific. Ie a very well ironed combo operating in a small rpm window with high port velocities will not benefit but an engine that operates over a wide range of operating conditions or less than optimal ports or fueling system should benefit (and probably why I find a rougher finish is better for me)

[Nick Ferri]

There is a lot of good and very accurate information that has been posted in this thread. It is up to everyone to be able to decipher and sift through it all. I was quoted just a few posts ago that texture is "application specific". That person was correct in me stating that in my original OP. I also said in my OP that I've never seen a smooth or mirror finished manifold or intake port work as well as a textured one. As most of you know already in here, airflow is not always relative to making HP. In other words, more airflow does not always = more HP. An airflow bench and a wet flow bench along with swirl meters and anything else people use out there are but just instruments. They are all very useful instruments but as I see it. They are just that, instruments. No different than a dyno! How many people in here have dynoed an engine or re-dynoed one and made more horsepower? Then go out to the racetrack and only spend weeks if not months struggling trying to figure out why the car runs slower. That answer to me is simple, it's called acceleration. We can all sit here and debate all day long what's best and what works best. At the end of the day, the only thing that matters is the scoreboard or the lap time. That's why I love what I do! In my case it's all about lightening up that scoreboard. Here's a speed secret that most don't ever think about. As an engine builder/engineer, I might try 10 valid things to R&D and test on the dyno or race track. If I'm lucky one or two of those things will show me instant results. That's the easy part! The hard part is to try and figure out why the 8 or 9 things didn't work. Trying to figure that out is what separates a lot of us out there in the industry. One more thing to remember. Always have an open mind in this industry! There have been so many things from the past that didn't work and now do because of other changes. So always be open minded to change even if you have tried it once before.
Nick

[jmarkaudio]

I think the biggest factor is the proper atomization, vaporization, and homogenization of the fuel with incoming air. When you do this distribution to all the cylinders get more equal, you can use less fuel and less timing because the cylinder burns quicker and at a more even rate. I've had a car gain a tenth in the 1/8 with a booster design change. I've seen a smaller carb make the same power as one that flowed about 40 CFM more because booster design made the distribution shown on 8 O2's more even, both 4150 carbs on an 800 HP BBC. Anything you can do to the induction to improve atomization and homogenization of the fuel in the induction without hurting the flow will improve distribution and resulting combustion efficiency, improving power. The only time I can see it possibly being detrimental is if the carb or throttle body is severely restrictive for the combinations, that results in high manifold vacuum at WOT and that large pressure drop will have a large effect by itself in vaporization of the fuel. But so far I have not been able to hurt power by over atomizing the fuel with a carb, the same with induction texturing as long as flow isn't disrupted I can't see anything negative coming out of it.

[900HP]

I think the biggest factor is the proper atomization, vaporization, and homogenization of the fuel with incoming air. When you do this distribution to all the cylinders get more equal, you can use less fuel and less timing because the cylinder burns quicker and at a more even rate. I've had a car gain a tenth in the 1/8 with a booster design change. I've seen a smaller carb make the same power as one that flowed about 40 CFM more because booster design made the distribution shown on 8 O2's more even, both 4150 carbs on an 800 HP BBC. Anything you can do to the induction to improve atomization and homogenization of the fuel in the induction without hurting the flow will improve distribution and resulting combustion efficiency, improving power. The only time I can see it possibly being detrimental is if the carb or throttle body is severely restrictive for the combinations, that results in high manifold vacuum at WOT and that large pressure drop will have a large effect by itself in vaporization of the fuel. But so far I have not been able to hurt power by over atomizing the fuel with a carb, the same with induction texturing as long as flow isn't disrupted I can't see anything negative coming out of it.

good points, Mark. We did some back-to-back with a Lil-Bo and our EMC legal 4150 with almost no difference in power between the two. The 4150 was so well sorted that the cylinder to cylinder balance was spot-on. The Lil-Bo needed more work in that area and there simply wasn't time to do it. The power increase we SHOULD have seen wasn't there and I'm guessing it was either atomization (4150 had killer annular boosters) or distribution or both.

As far as "the same with induction texturing as long as flow isn't disrupted I can't see anything negative coming out of it"

Chad Speier and I had this discussion last night. Our conclusion is at the very worst you don't see an improvement in performance with the burr finish. He hasn't had one yet that showed a LOSS in performance. Even his record setting NHRA class legal stuff is burr-marked (where allowed). So if in our testing we are not seeing a loss and are seeing improvements then we have to come to the conclusion that it is worth the extra effort to go for the textured finish. There is more than one reason we left the ports in our EMC heads "as CNC'd" but there are still a couple of places in the ports where they are burr-marked.

[nickmckinney]

I posted this in the other thread and it makes you wonder what is really going on in an intake. I port match the plastic intake manifolds from the Ford 4.6 pretty often. Here I run a strong shop vac to the throttle opening and tape off all 7 other ports. With the shop vac pulling in one direction only one would think the tape on the other ports would stay clean, but they are always covered in the plastic shavings. This is a very long runner intake with ports making a 180 plus turn.

I too tried the rough texture on a roots blower combo we have done tons of. It made more power than we were expecting and we had to dial the tune down some (stock shortblock limit) but with no ABA testing I have no idea how much was with the texture. My customer base thinks a rough texture means I did a crappy port job so they dictate that I polish smooth no matter what anyway (I polish to 60 grit)