207 replies to this topic

[LarryKing]

Transparency: My first "pro" motor (1.6) was my car's original engine that I took to a local machine shop, along with my FSM, having them rebuild it with new oem Mazda pistons, rings, bearings, valves, valve springs and lifters. I told the shop to rebuild the motor to exact stock specs following the FSM. I foolishly believed my competitors were doing the same. With some dyno tweaking of timing and A/F clockspring the motor made a whopping 109 HP. A couple roadtrips to the SEDiv was all it took to see that my efforts were a waste of time and money. I bought a Rebello motor and ran it with decent results. After a few seasons the Rebello was tired, and with limited funds, I retrieved my original "pro" motor from the shed and purchased a Stewart head. Doing nothing else other than readjusting timing and A/F the motor made 118 HP. Same bottom end as the 109 HP version.

 

My point: When I read that plunge cuts are necessary to even out manufacturing variations my bullshit meter goes off. The primary reason for machining an SM head is to make more power, regardless of the reasons we are trying to sell to the CRB.

 

But does it make the class better?

[38bfast]

King IMHO I am sure the 9hp gain is not just plunge cuts or STR. 

[Tom Hampton]

And, when someone makes a claim about statistical variation based on a sample of one (1), my BS meter goes off.

Nobody said it didn't make more power, the claim is that they result in more consistent power across the population. Granted no one has posted any data to substantiate that claim, either.

Your personal anecdote of one motor in two different configurations dyno tested X years apart doesn't prove anything either. In fact, it doesn't even address the question.

[Caveman-kwebb99]

i got 8 more hp with same engine on same dyno on same day once  with same full engine...  

 

I guess it was the magic fairy dust I sprinkled in the hubs...  

[LarryKing]

My point is that a "pro" motor and/or "pro" head make considerably more HP than an oem equivalent. Does anyone dispute that?

 

Are "pro" motors what is best for our class?

 

Mr. Hampton, have you entered a race in the past two (or three) years? I'm just wondering how much skin you have in the game.

[pat slattery]

I think the class has left the station, using 150K junk yard motors Mr. King.  I sealed crate would be great, but they aren't even making crate motors anymore.  A pro motor is fine with me but lets keep the rules creep to a minimum and the motor cost as low as possible.

[Brandon]

Sometimes I wonder if I'm in an echo chamber but then realize I'm the one repeating what's previously been "said"....oh well.

Seconding Slattery & Hampton here - using a single source of evidence as proof of a larger concept indicates confirmation bias (at the least).

 

Regarding the 1.6L heads, there have been broad statements & observations made confirming the sad state of manufacturing 'way back when'.  Additionally, equally variable levels of quality were seen in even the 1.8L heads thus leading to an establishment of a machining process to eliminate these variables and provide a larger source of available cores for building of any engine whether it be pro/amateur/"shop down the road".

 

The happy outcome of these machining allowances was two fold for competitors: no need to stock-up on multitude of cores to find the 'sweetest one' to build from and a bump in overall output.

If one would like to claim the rule allowance thus "increased costs" for competitors, there is no "requirement word" ("must") in any of these machining rules entries so I would respectfully disagree with that claim.

 

The rules place no limits on where a competitor is allowed to source their engine.  If it happens to be a 150k salvage that's your prerogative (or budget) dictating that.  Don't let the rules (or the subject of this thread - their "transparency") get in the way of a poorly-based position/opinion debate.

[LarryKing]

Does anyone have evidence of the HP delta from cherry-picking stock motor components?

 

Two HP? Five? Ten?

[FTodaro]

Maybe this is a discussion for another thread but much of thrust of the SM rules and Creep containment, are based on the idea that SM is supposed to be a low cost, entry level racing class. I agree, but the next fair question to ask is what is the measuring stick to be used to measure if the class is low cost "good for the class".

 

I have no problem with the cost of a pro motor, and I have no problem with what you can spend on an SM to get it to the point to be a top prepped car, I have seen some people complain that a top notch SM can cost 30,000.00 Plus.

 

My rebuttal:

 

1) cost is relative, the cost to build, maintain and race a season in SM is far less  than most all other organized classes.

2) Budget is based upon you personal preference, do you want to race 10 HC tires or 2 HC, you do not have to do either one but you have a choice.

3) competitive car cost, you can do the work yourself and build a top prep car for well under 30,000.00 but you have to do it yourself and know what you are doing.

 

To me this class is and should reward, drivers who are willing to do their own work, but if you want to do it right, its never cheap.

 

The above is one of the reasons i have backed some of the expansion to the rules and we are well beyond running the junk yard motors and IMO we should be.

[Brandon]

Why should we have to prove your false conclusion?

 

The fact of the matter was, prior to the machining rules, folks were performing said picking of cherries in an effort to eek out the last bit of performance advantage from the collection of parts they had.

Some would claim the same thing is still happening with the other components involved (intake, exhaust) but the gains thereof are now within the noise of the dynomometer (notwithstanding any outlier in terms of a negative result with any part).

What was the source of this minimization in performance deltas across your build options?  The machining rules change.

Being allowed to baseline whichever head you decided to use to a lowest (greatest in actuality) common denominator of measurements allowed a "flattening out" the performance differential between builders (see "pro/amateur/shop down the road" above).  This, in turn, would also bring about a relative lowering in the costs of building an engine - of any source/caliber.  

(Caveat - inflationary pressures I'm sure have made this cost reduction quite possibly non-existent in this day and age...)

 

Again, note the words used: "building an engine" as opposed to "installing any engine"

 

To participate in this class, you must follow the rules as stated.  These rules do not dictate how much you can/cannot/should spend in participating in this class.  If you want to build an engine, the rules allow it.  If you want to run a street engine, the rules allow it.

 

The sanctioning body has a goal of allowing a 'low-cost, production-based race class' to participate at its highest levels of competition.  Current SM rules support this and we have the (nearly) highest-subscribed class in national competition.  It's up to you to decide at what level of capital you wish to commit to participate.

 

As Frank has noted, costs are relative based upon your particular capital-base and those with the most capital will generally have a better prepared/built car and that's just a fact of life.

 

Now, how in the hell did we get into a parity debate in a "rules transparency" thread?!?!?

[Tom Hampton]

My point is that a "pro" motor and/or "pro" head make considerably more HP than an oem equivalent. Does anyone dispute that?

Are "pro" motors what is best for our class?

Mr. Hampton, have you entered a race in the past two (or three) years? I'm just wondering how much skin you have in the game.

I don't know how the question is relevant, but the answer is "none". I have a car that I built with my own hands (minus the motor), I have nasa and scca memberships, and I drive as often as I can. I have spent the last three years traveling back and forth to new Zealand on business. I don't have the resources to do "arrive and drive". So, the car sits while I have traveled. That contract is coming to a close, and I only have 1 or 2 trips left. So, my "skin in the game" is ratcheting up for 2015 with my expectation of being able to get serious about it again.

I have a pro motor. But, I didn't get it for the "power". I fully intended to drive the original motor into the ground and buy a junkyard motor and rebuild that myself. But, the decision was a time optimization choice, given my travel schedule.

But, your "story" means nothing. Again, no one has ever claimed that a plunge cut head made equal power to a non cut head. Again, the claim has been that it reduces population variation.

However, no one has ever posted any statistics for that claim. Nor have they produced dyno numbers or anything else that is remotely meaningful to substantiate the variability claim.

The claim makes intuitive sense, but I've been an engineer for far too long to rely on intuition for things like fluid dynamics. I've been there, done that, and have several mental scars from it.

I find it highly unlikely that the 'super special head committee" will spend the resources to answer that question with any statistical validity. The sample size would need to be prohibitively large to ensure it encompasses the entire population variance. I doubt there is anyone associated that even understands the DoE issues well enough to do it right.

And to bring this back to the original topic, they have not shared ANY details of the test program. Someone said it was "impressive". But, if they aren't testing 10s of heads from each generation at every phase of the machining process repeatedly, then it's just more meaningless data mostly designed to confirm someone's desired course of action. Eg: "see, we told you stock heads were better."

[LarryKing]

 

Why should we have to prove your false conclusion?

I'm not asking anyone to prove/disprove any conclusions. Just best guess - how much HP is gained by parts bin shopping? Example: I've read that in Spec Racer Ford the delta between all engines is < 2 HP.

 

 

how in the hell did we get into a parity debate in a "rules transparency" thread?!?!?

We who? No one said a word about parity in this thread until you posted this.

 

 

I don't know how the question is relevant

Race in this class for 13 years only to see the constant escalation of cost and the front of the field get farther and farther away and then ask how it is relevant.

[Bench Racer]

Talk all you care to about Spec Miata cost to prep and race a car. That "Purpose and Intent" low cost went out the window when Spec Miata became a national class. Many of you haven't been around since the original JD, made the statement, be careful what you ask for. Because you'll get it.  $$$$$$$$

 

ps:

The fact that Tom Hampton owns a Spec Miata is all it takes for him to have skin in the game.

[LarryKing]

PSS: I own a pretty nice guitar but I can't play it for shit, so I avoid guitar forums.

[Bench Racer]

PSS: I own a pretty nice guitar but I can't play it for shit, so I avoid guitar forums.

This tangent ^ may be going astray. Some might believe your implying something your really not implying.

[Duncan]

However, no one has ever posted any statistics for that claim. Nor have they produced dyno numbers or anything else that is remotely meaningful to substantiate the variability claim.

The claim makes intuitive sense, but I've been an engineer for far too long to rely on intuition for things like fluid dynamics. I've been there, done that, and have several mental scars from it.

As an operations research analyst, I completely agree with your sentiment. There's very little data out there, and while I also think the claim is intuitive, I've been proved wrong enough times by data to be cautious.
 

I find it highly unlikely that the 'super special head committee" will spend the resources to answer that question with any statistical validity. The sample size would need to be prohibitively large to ensure it encompasses the entire population variance. I doubt there is anyone associated that even understands the DoE issues well enough to do it right.

I also agree it's unlikely that the committees test sample is large enough to make a high confidence level statement about the difference in performance between a stock head and a plunge cut head.

But I definitely agree with you on principle, that given the likely small measurement difference in HP between a stock and plunge cut head, you'd probably need a fairly large test sample. It would be really interesting to see the raw data, although I doubt that's something that would ever get released.

Duncan

[Johnny D]

You better hope it's accurate or you know what you're going to get in 2015.

Besides a 35 page parity thread here.

J~

[LarryKing]

One more time, with feeling. I'm not talking about junkyard engines or even necessarily budget builds.

 

Question: Two brand new crate motors. One gets sent to a Mazda dealer to be disassembled, measured and reassembled to exact oem specs and procedures. The other goes to (pick a name) professional Spec Miata engine builder for whatever their standard build procedure is.

 

Which engine makes more power?

 

Which engine best conforms to 9.1.7.C.1?

[Johnny D]

1) What crate engine, 1.6 ? 1.8 ? 99 ?

 

2) What are the specs to building a engine at this point ??

 

3) Are there any modes to any year engine to make parity ??

 

4) The head test results are just a small piece of the pie to make Parity

 

So what are you talking about now, based off of this ^^^ ??

 

Please start you sentence with, "will if, ifs and butts were candy...."

 

J~

[Jamz14]

The second engine sent to race builder makes more power.

 

Reason, OEM specs just mean that the parts are within the spec tolerance. Race builder selects parts that are within the tolerance but also matched to themselves.

 

Second reason, professional engine builders are not constrained by the rule that says if it doesn't say you can....you can't.