I played high school golf in Florida. As always, we were unable to drive carts because they are not used in tourneys, so it was _exercising_ in a pure sense. Hell, my dimples helped me get through the air/water suspension!

 

Dimples are used to reduce drag in many non-spinning applications. It just depends where you put them.

Show me a pro stock engine builder that is polishing ports, intake or exhaust and I'll gladly eat my words.

I've seen many polished exhaust ports, not only did they not flow any better they collect carbon equally as well as unpolished ports and are no longer polished after a short run time...

 

Wow, such diverse opinions.

The proof is in the pudding, as they say, so where is the shootout?

It so hard deciding on stuff when there is no emperical data.

 

there is a huge range between the factory "as cast" roughness and what Endyn does, which is a grained, sanded finish (what most head workers do). A true polish (would be known as a mirror polish) is a waste of time. A better area to focus on is the gas flow/port shape directly behind the valve and how more of the mix gets into the cylinder early as the valve opens and doesn't blow right out the ex port. Endyn spends a lot of time on the at area; look at the pics above of his cc; better yet, check out his site for the mini headwork, you can get an education.

http://www.theoldone.com/components/...ead_modifi.htm

by the way, it is bogus to claim you are getting 200+hp because someone else did. If you didn't measure it, you are only guessing.

 

I'd be curious to learn of a few of the many applications. It has certainly never been applied to any of the military ships or submarines that I have worked on nor has it been applied to any production or prototype US aircraft that I am aware of, all applications that would love to minimize drag.

Regardless, I probably should have emphasized that the port shape is far and away more important than the surface finish of the port walls. But I thought the discussion was whether surface roughness helped or hindered air flow. In that context smoother is better.

Perhaps I used the word "polished" too loosely. A mirror finish is a waste of time. But many of the shops use the term polishing to describe improving the surface finish of the port or combustion chamber, mirror finish or not.

The point was that ports are left with some degree of roughness to improve air fuel mixing not to increase flow rate. That is why the exhaust ports are often machined to a smoother finish than the intake because air fuel mixing is no longer a concern at that point. My understanding of the previous posts on this thread is that is exactly what Endyne does. And, although I don't know about Pro Stock, NASCAR builders have been doing V-8's that way for 40 years or more.

 

The time trial skin suit worn by Lance Armstrong in the 2005 Tour de France had dimples on the back. It was measured in a wind tunnel and proven to reduce drag. This was shown on an episode of Chasing Lance on the Discovery Channel.

 

Have a look at this article.

 

...ah yes, but the JCW GP has 8bhp more than the current JCW. Perhaps they're following this thread.

The kit inludes a body that is nearly 90lbs lighter than?, areo aids that "significantly reduce aero drag", Standard DSC and LSD, no rear seats or sound deadening, JCW suspension, a questionable colour scheme and some very ugly wheels.

Hurry, only 2,000 will be produced world wide...at nearly 30 grand for a typical JCW car, this one should go for what, 35 grand? I wonder if the JCW folks have ever seen an EVO?

 

High level competitive swimmers pretty much all wear swimsuits with some kind of surface texture to reduce drag. When they were introduced, these type of suits were actually so effective that they were initially banned from use in US competitions. See article here.

 

Like fish, as I wrote above. It's in the scales. Water behaves in a different way than air even though both are technically homogeneous solutions.

 

Fascinating. Could it be because of the difference in density of the two mediums (slinks back to nontechnical corner and redoffs dunce hat ).

 

Cliff notes:

1) Smooth and shiny isn't necessarily better.
2) Nobody has done comparisons between the different heads on the market.

 

Way to be succinct, Andy! I absolutely love it!

Thanks,

Paul

 

i recently heard of a test to see whether a swimmer would travel faster in water vs. more viscous fluid; what do you think?


as far as the JCW head; Cooper has been around cars for a long time. I doubt the JCW head is his best attempt (sadly, due to Mini compromises, warranty, etc.)

 

According to this article, the golf ball dimples do accentuate the lift from the spin of the ball. But the main improvement comes from maintaining the turbulent boundary layer to lower Re, so that it stays attached farther around to the back of the ball, thus reducing the pressure drag. I'm really not sure if the turbulent boundary layer has application to improving flow in the head. But whether it does or it doesn't won't be affected by the fact that the air-fuel mix is a suspension.

http://wings.avkids.com/Book/Sports/...r/golf-01.html

 

Need that. How to make a decision just based on marketing hype?

 

The swimming pool test was done by Ed Cussler at the U. of Minnesota. The more viscous fluid gives more drag, but also more to "push against" when you stroke. The net result, if I recall correctly, was that the two cancelled out and the swimmers were about as fast regardless of fluid viscosity!

 

To compare the effectiveness of different manufacturers head porting a side by side comparison is absolutely needed!

I don't want this to degrade like the original "How the MCS Engine Makes Power" thread did so I'll drop the surface finish discussion after this. I appreciate the specific examples, its interesting that they are all bio-mechanical in nature where the speeds involved are relatively low.

The link posted about the swimsuit credited the swimsuits ability to compress muscle and reduce muscle vibration to the improved performance as much as the textured finish. It then goes on to say swimmers have gone to teflon coating the swimsuit to reduce drag and trap air for increased bouyancy, again implying the texture may not be all that its cracked up to be. Finally, an article on the swimsuits in the July, 2004 issue of Science magazine had as many experts that believed the suit's texture did not reduce drag as those who did. The texture effect could be as much marketing as some claim the finish on the head ports are.

The Lance Armstrong suit is interesting, I will try to learn more.

I've heard the argument used in http://wings.avkids.com/Book/Sports/...r/golf-01.html
before but I am not to sure about it. The explaination given in that particular paragraph is weak at best, and the last sentence is almost nonsensical. It then goes on to say the dimples do help the spinning ball make more lift and, lastly the only measurements it mentions are for spinning golf *****.

As for fishscales, they are simple a good system of protective armor that is still flexible enough to allow the movement they need. fish secrete a layer of mucus to help them slip through the water. Note the sharks, supposed inpiration for the swimsuits above; they are at the top of the food chain, no need for armor so no need for scales.

Anyway, again, if the subject is just to compare heads there are enough other variables that only a test under the same conditions would be a valid comparison. If the subject was the effect of surface finish, I still maintain that a smooth pipe will flow more air than a rough pipe all else being equal and with that there are reasons for leaving the intake less smooth (enhanced mixing).

Thanks for your patience as I am still far from succinct. By the way any spelling or punctuation errors you find were put there on purpose for your entertainment and to keep your interest!!

 

The problem facing swim suits and cycling gear is body shape, size and amount of sweat, and, fresh and salt water...or dirty water in addition to physical fitness; I trained and raced 12,000 miles last season. The difference between a good and bad day in the saddle will overshadow clothing advantages.

We're not motors.

 

I see above points, but agree with Andy that an objective comparison is needed, else this discussion is going no where...unless we want to bash JCW which doesn't have a staff representative present on this board...

I am still impressed that BMW took the risk to sell a tuner package at all, installed post delivery, give a warranty... with a tuning kit that includes a cylinder head, injectors, software, intake, plugs etc.... The head is meant to increase power, and is better than stock most would agree, no it's not a custom tuner head, but just an improvement to stock, like the whole JCW package... with the belief that less is more in this case, sometimes too much garlic is just too much garlic...

My question in this thread, (other than data flows), if the JCW tuning package cost less than $1,700 (Randy's price is a bit more for about 210 hp I think which includes pully, belt, plugs, intake), would people be anti-Webb tuning kit? or more precisely.. is criticism based on cost only, or is that bmw is owner, or jcw not supplying quality (crappy),,, or ummmmmmmm

 

Certainly, for flow in a pipe, a smoother surface will give a lower pressure drop. The only time the rougher surface helps is in cases where boundary layer separation occurs. As some one else noted, airplane wings are shaped so that does not occur. Probably, it doesn't happen inside the cyl head either!

 

To have a fair head comparison, how would you set guidelines? Budget restrictions? Constant component sizes (e.g., valves)? Is the measure of merit peak HP or area under the curve? I think you would have to provide info on the engine it is to run on, like the mods it has and the target RPM range.

 

I dont think it matters cause it prolly will never happen.

 

The only testing we have been able to do are comparitive dyno runs to the Cosworth, Pilo, JCW, and our own.

If anyone wants to shoot their aftermarket head over here, I will gladly put it on the flow bench for comparative purposes.

Our head has given us the best results on the dyno, by a good margin, and from the flow numbers I have seen, we also have the best exhaust flow rates. The intake ports are easy to get, but if you just ram as much air in without getting it out efficiently, it doesn't make power. You have to have the right ratio.

I actually had a vendor who had seen my head and the Pilo head tell a customer that the Pilo head was better. I called to ask what that opinion was based on, and he said it "looked smoother". That's not where it is at.

There are serious laminar flow considerations that can't be shown on a typical flow bench either. So, while CFM shows how much capability the head has, it doesn't tell the whole picture. We DO flow bench each head though, and that chart comes with the head.

Our head is the biggest bang for buck in the cylinder head world, hands down. We charge $1855 which includes the Schrick cam. That also includes larger valves, the porting, the flow benching and the valve grinds, as well as the head job.

You can upgrade for additional cost, but I feel it is a waste of money. The product we sell has everything needed to optimize the MINI cylinder head.

Feel free to contact us with any other questions, and if you want a head that is not yet installed flow benched, just let me know.

Hope that helps!
Randy

 

Sometimes Customer service is HUGE .... It is a BIG $ Upgrade, a few hundred dollars difference in vendors

If someone is there to answer questions, return phone calls, e-mails and promises the product by a certain time ... That is the one who gets my business