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#12156 - 12/18/15 06:22 AM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: rick haynes]
fordboy628 Offline
Professional

Registered: 06/30/14
Posts: 311
Loc: NE Illinois
Originally Posted By: rick haynes
who is Harold Bettes.


A professional engineer and former VP of SuperFlow Technologies. Also a member of ASME. He was also instrumental in SuperFlow's sponsoring the first Advanced Engine Technology Conference (AETC), now run in conjunction with the Performance Racing Industry Trade Show in Indianapolis.

His book on dyno testing and tuning of engines/race engines, in collaboration with Bill Hancock, is the definitive resource on the subject. His book on engine airflow is also an industry standard.

Since leaving SuperFlow, he has formed Power Technology Consultants.

Power Technology Consultants

You should read his books.

Cheers
_________________________
Fordboy628

Without "data", you are just another guy with a theory or an opinion . . . .

Someone who thinks logically is a nice contrast to the real world . . . .

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#12164 - 12/18/15 02:19 PM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: fordboy628]
hoffman900 Offline
Champion

Registered: 02/03/11
Posts: 542
Loc: New Jersey
Mark,

I just looked at the Landspeed thread and saw "ARP studs replacing the long bolts". I have an old Race Car Engineering burried somewhere at my parent's house that specifically talked about this and how too stiff of bolts were causing problems for the BTCC builders. I'll try to dig it up over the holidays and scan it for you.

Cheers,
Bob

Edit: someone already did it:








Edited by hoffman900 (12/18/15 04:54 PM)

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#12553 - 01/31/16 12:51 PM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: hoffman900]
fordboy628 Offline
Professional

Registered: 06/30/14
Posts: 311
Loc: NE Illinois
Thanks Bob for posting this.

I've seen some of it, but not the entire article on the K series.

Cheers
_________________________
Fordboy628

Without "data", you are just another guy with a theory or an opinion . . . .

Someone who thinks logically is a nice contrast to the real world . . . .

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#12554 - 01/31/16 01:05 PM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: fordboy628]
fordboy628 Offline
Professional

Registered: 06/30/14
Posts: 311
Loc: NE Illinois
For anybody trying to analyze data in a numerical table format


Of course Excel is used by many. But if you are unhappy about the way Excel graphs your data, I offer 2 alternatives:

1/ Grapher V11, by Golden Software. A great program, lots of features and flexibility, great output. $489

http://www.goldensoftware.com/products/grapher

Probably more capability than the enthusiast needs. Back in the dinosaur days of DOS, I used Grapher a lot. The latest version runs under Windows. Sorry no samples. They are all on my DOS "Frankenputer".


2/ DatPlot V1.4.8, by Michael Vogt. A more basic program that still allows use of a Y2 axis with differing values from Y1. $ Freeware

http://www.datplot.com/

No manual, but has a help page and a user guide. Some samples below:









I still graph in Excel, but DatPlot gives me formatting control over the visual presentation in a way that Excel does not. Datplot allows zooming and panning and can show data values along a user chosen cursor line, much like analysis programs from Performance Trends. DatPlot is not as flexible or as powerful as the PT software, BUT, it is free. You do have to export your data file into a pure text format, prior to importing that data into DatPlot, which is an extra pita* step, but, WTH, free. Printing hardcopy can be tricky, but exporting and saving as photo files or other images easily inserted into text documents, is easy.

If you are struggling with columnar or other tabulated data, give DatPlot a try.

cheers
Fordboy
_________________________
Fordboy628

Without "data", you are just another guy with a theory or an opinion . . . .

Someone who thinks logically is a nice contrast to the real world . . . .

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#12683 - 03/08/16 07:28 AM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: fordboy628]
fordboy628 Offline
Professional

Registered: 06/30/14
Posts: 311
Loc: NE Illinois
If you want to get smarter . . . . . .


For those who have not embraced modeling or simulations because of the cost, this is a really sweet deal.

$768.00 worth of data crunching programs and the like for $99.00

http://speedtalk.com/forum/viewtopic.php?f=12&t=45833

It is worth it for the audio interviews, "Engine Pro" and "Density".

There is a time limit on this offer, so don't think about it for too long. The deal runs until 3/15 only, and must generate 200 sales. If 250 sales are reached, "PipeMax" will be added to the bundle.


This type of data analysis is NOT futuristic. I suggest you embrace the present if you want to get smarter . . . . . . and avoid piles of shiny, useless parts . . . . . .

BTW, in the interest of full disclosure, you will have to put some effort into "getting smarter", after pushing the button to purchase. Think of that effort as part of the price of your "education".

Cheers
_________________________
Fordboy628

Without "data", you are just another guy with a theory or an opinion . . . .

Someone who thinks logically is a nice contrast to the real world . . . .

Top
#13838 - 05/06/17 09:28 AM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: fordboy628]
fordboy628 Offline
Professional

Registered: 06/30/14
Posts: 311
Loc: NE Illinois
OK, it has been a while since I've posted here, for a variety of reasons, but mostly because I have been too da** busy.

What has prompted me to get back on my "soapbox", has been the recent interaction with several racers who are under the impression that cylinder head development, and/or modification, and/or restoration, happens when "someone" waves a "magic wand" over their cylinder head(s). This is not the case. It happens when you employ a "knowledgeable" and thorough professional to put your head(s) into the waiting line of projects in their shop. Any "pro" worth a sh**, has a backlog of projects, AND, they are worth waiting for, because they will "document" the airflow, not just after, but before any work/modifications are undertaken. This "proves" the value of the work, not only to the customer, but to all their "airflow expert buddies" as well.

And I am compelled to comment that if you have never done any airflow testing and/or only read magazine articles or books about it, YOU are NOT an "airflow expert".

Some basic free cylinder head advice for anyone:

A/ Read more of my technical thread on this forum: RACING ENGINES, A TECHNICAL EXAMINATION. Focus on the flow testing parts. As you are doing now.
B/ Don't believe everything/anything you are told, UNLESS you are shown DATA that backs up the person's claims. When I redo heads for a client, I provide "before" and "after" flow test data to substantiate flow increases. You should get the same. If you do not get this critical information, you need a new cylinder head shop.
C/ Keep in mind that in "engine engineering" things are not simple. What works for one style of cylinder head, probably will not work the same way in another style of head. IE: Triumph Vs BDD; Or say Chevy SB Vs Ford SB, etc, etc.
D/ PROPER flow testing fixtures are needed to generate reliable test data. This is an investment, as the purchase is expensive or the fabrication is time consuming.
E/ Enlarging the ports will RAISE the peak power RPM proportionately, presuming that there is no other "choke point" somewhere else. Make sure that is what you want to do, as more rpm = less time in service. Large ports for a "lower" rpm engine, typically result in lower than optimum gas speeds through the engine. This is not good and it is not smart . . . . . .
F/ Yes, it is easy to loose flow with valves that are "too large", on some types of heads. And this is counter-intuitive to what "all knowing experts" will tell you. Notice that they do not provide any DATA . . . . . .

When someone starts by saying: "I have a theory about . . . ." OR, "I've done lots of these. I know what you need. No flow testing required." RUN, do not walk, in the opposite direction as fast as you and your wallet can.

You want to find the shop that says: "Let's test what you have so we can establish a baseline of performance Vs other cylinder heads of this type that we have tested in the past. Then we can intelligently determine whether your head is good or bad or meh, and what we might be able to do to correct it or improve it."

Spend your dollars wisely and effectively . . . .

Cheers
_________________________
Fordboy628

Without "data", you are just another guy with a theory or an opinion . . . .

Someone who thinks logically is a nice contrast to the real world . . . .

Top
#13840 - 05/06/17 02:36 PM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: fordboy628]
V8vairmike Offline
Winner

Registered: 05/10/14
Posts: 434
Ive spent some time on the flow bench with my Corvair Heads with a Gentleman here in North Georgia, Wow, you really need someone who understands flow before you start moving that port around. What you think you need to do may be completely wrong. Especially when your dealing with a Poor intake design (small log with two carb pads on top and 3 ports below all at different lenghts from each other! Exhaust valve size determining header tube size. You can really get yourself in trouble if you just assume bigger is better.
Mike

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#13844 - 05/07/17 07:49 AM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: fordboy628]
Hap Waldrop Offline
Champion

Registered: 02/03/11
Posts: 781
Loc: Greenville, SC
What brought all that on Mark? I port a lot of heads and most of them are for the street and most of them are what I call a street port, meaning do the things that make the most gains, and don't the things the produce the least gains, and that plan nets less labor, and puts the job in range where people want to pay. Before I did street port heads, I did maybe 8-10 heads a year, now we do 50 heads a year, maybe 5 on them end up on race cars, and those heads are twice the amount of labor charge and the final cost depends on parts used. Now I am going to be a doing a 1275 heads soon, that will let explore the limits, and the flow bench will get a good work out on that head, but for every customer you have that is seeking near perfection and willing to pay for that, you got 10 more more who want to pay less and get less. If you took every MG race engine builder in the country, and every one of their customers who told the builder to seek the limits and they were unconcerned about cost, you could put them all in a Austin Mini and have room left over smile

Then there is the school of thought in head porting of theory vs ability to do the labor, seldom do the two reside together. Making a die grinder do what you want it to do is an art form, that very few possess these days, a lost art if you will. At the end of the day if my business model was to only take on customers who wanted to swing for the fences, it would be a lonely shop with less of us would be working there. I have long comes to grips with to have a busy shop, I have to appease the masses, and the jobs where I am truly tested are far and few between. In essence the whole idea of vintage racing defeats that train of thought. I think of vintage racing for the most part kinda like dumbed-down engines, compared to the days of 15-16 to 1 SCCA motors and if one only wanted to do nothing but SCCA motors, well MG motors anyway, you could not even keep groceries in the fridge. Less than 5% of the runoffs racers are even looking to push the limits, in fact I find most SCCA racers to be cheapskates, even some that are champions.

You won't hear many engine builders say this out loud. I tell most of my customers, sure I can help you go faster, but a good engine will only get you so far, if you want to go faster, the thing that normally needs the most improvement is you. Hell these days I am happy if a customer can use a timing light, look at a gauge and remotely find a apex smile
_________________________
Hap Waldrop
Acme Speed Shop 864-370-3000
www.acmespeedshop.com
MG/Triumph Performance Street/Race Engines
The Vintage Production Car Festival
https://www.facebook.com/vintageproductioncarfestival

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#13845 - 05/07/17 09:00 AM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: Hap Waldrop]
fordboy628 Offline
Professional

Registered: 06/30/14
Posts: 311
Loc: NE Illinois
Originally Posted By: Hap Waldrop
What brought all that on Mark?


Hap,

Usually not guys from this forum. It is the result of recent dealings with V8 guys who DO NOT understand that poor selection of casting type LIMITS what can be done with a cylinder head for a given application.

BUT, this type of person exists in the vintage world as well. Again, certain castings are better suited for some types of engines, as opposed to other situations. And this is the problem: "Why can't someone make my early type casting into the latest and greatest??"

I just want racers to think about what they are trying to accomplish ahead of time. As opposed to going out and buying the cheapest parts first and then complaining about it when they are told their parts are unsuitable for what they are trying to do.

This was not directed at street or budget type guys, or those who provide services to them. In my experience, they at least recognize the limits of what they are doing and are able to deal with "reality".

It's the "Why can't you make a silk purse out of a sow's ear?" reality deniers and the "How could THAT have taken that much time??" guys who are reinforcing my interest in a fly fishing retirement . . . .

BTW, there are V8 guys who cannot use a timing light too. And they are unable to properly adjust their valve lash, or select and change their carb jets and accelerator pump squirters/cams. The "Trifecta" . . . . . .

Cheers
_________________________
Fordboy628

Without "data", you are just another guy with a theory or an opinion . . . .

Someone who thinks logically is a nice contrast to the real world . . . .

Top
#13846 - 05/07/17 09:37 AM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: fordboy628]
Hap Waldrop Offline
Champion

Registered: 02/03/11
Posts: 781
Loc: Greenville, SC
I hear you Mark,I recently had a guy tell me when I ask him about a possible lean fuel mixture being his issue, "well it was set where the builder put it when he dynoed the engine". I don't even know where to go with that level of cluelessness.

I am quite sure I am not telling you anything. When I raced SCCA National, we would record fuel mixture settings based on changing weather conditions,if you got it right it could be worth a car lenth, or maybe two over your close rival. I have seen the same two cars with untouched engines run 1-2 car lengths over the next guy at given track, meaning one track racer A had the advantage at that track 1 , then the exact opposite at the next track, I can not equate that to anything other than fuel mixture, and or timing, although for me mostly timing at one point and then I just adjust fuel from there from data I get from EGTs and AFR. To be honest with you, I see plenty of evidence that two different cars that are very much the same, need more, or less adjustment, the Biscuit seems to like set it, and forget it mode, where Bamm Bamm, the 1275 FP Midget responded well from micro adjustments, meaning a couple flats up or down. I used to record jet height settings based on weather conditions, so I could use them later on.


Edited by Hap Waldrop (05/07/17 12:29 PM)
_________________________
Hap Waldrop
Acme Speed Shop 864-370-3000
www.acmespeedshop.com
MG/Triumph Performance Street/Race Engines
The Vintage Production Car Festival
https://www.facebook.com/vintageproductioncarfestival

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#13847 - 05/07/17 09:24 PM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: Hap Waldrop]
fordboy628 Offline
Professional

Registered: 06/30/14
Posts: 311
Loc: NE Illinois
Something I'm sure you know: Mixture sensitivity is a function of how highly tuned the engine is. Lower specific output = less sensitivity. Higher specific output = more sensitivity. And, of course, when tuning "close to the edge", keeping the state of tune on the "safe side of the edge" requires constant monitoring to ward off "disaster".

True recent story . . . . .

Drag guy comes into the shop where I pay for machine time. New potential customer asking a lot of questions, you know to: "Make sure the shop is competent." (Shop owner is a record holder and grudge night winner at a nearby drag strip.) New guy then proceeds to show all shop persons a spark plug from his recent foray down the same strip. Said plug has the side electrode melted off . . . .

His question was: "Could the engine have been too lean?" grin

Because his carb guy swears that the jet setup he is using is: "spot on".

When I suggested he perform a leakdown check to judge the "condition" of what remained of the engine, he asked: "What for?"

This guy is not a total neophyte, and of course has plenty of dough to spend, but thinks that all shops are just "ripping him off".

There is only so much that can be done to try to help those such as this guy. And when they are unwilling to listen to those with more experience and/or knowledge, well, that is the point where I lose interest in their "education" . . . . .

Cheers


Edited by fordboy628 (05/07/17 09:37 PM)
_________________________
Fordboy628

Without "data", you are just another guy with a theory or an opinion . . . .

Someone who thinks logically is a nice contrast to the real world . . . .

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#13848 - 05/08/17 08:40 AM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: fordboy628]
JohnJ Offline
Wannabe

Registered: 05/31/14
Posts: 5
Loc: NC
Yes there is a LOT to be said for good head work. We recently spent a lot of time on the engine dyno with two engines; one was the engine that I have been running for year and it had served me well and had put me at the pointy end of the line consistently, it is a 1275 with n old Comptune head, the other is identical bottom end and even has same valves springs etc with the only difference being in the intake porting. The engine shop did some radical work bringing their latest V8 work to my little 1275. The end result was that the new engine produced 10 more hp and raised the rpm from 7000 to almost 8000. To do this I had to go back and massage some SU needles to feed it more.
John

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#13860 - 05/09/17 08:31 PM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: JohnJ]
hoffman900 Offline
Champion

Registered: 02/03/11
Posts: 542
Loc: New Jersey
Originally Posted By: JohnJ
Yes there is a LOT to be said for good head work. We recently spent a lot of time on the engine dyno with two engines; one was the engine that I have been running for year and it had served me well and had put me at the pointy end of the line consistently, it is a 1275 with n old Comptune head, the other is identical bottom end and even has same valves springs etc with the only difference being in the intake porting. The engine shop did some radical work bringing their latest V8 work to my little 1275. The end result was that the new engine produced 10 more hp and raised the rpm from 7000 to almost 8000. To do this I had to go back and massage some SU needles to feed it more.
John


Absolutely, it's all in the cylinder head. Everything else is to make it work better.

Out of curiosity, how does the power look for both engines at 7000rpm?

I know someone else who had a head done. Same valve sizes, more talented and different head porter (and the previous porter gets a lot of good press). 15hp more with the new head and peaks are pretty close...

Aaron Kelly's bottom end and valvetrain was pretty typical on the Saurino car, but a lot of development on the cylinder head and exhaust took that engine well past where Comptune was with it.



Edited by hoffman900 (05/09/17 08:31 PM)

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#13861 - 05/09/17 08:59 PM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: hoffman900]
dcb Online   content
Legend

Registered: 01/24/11
Posts: 1000
Originally Posted By: hoffman900
Aaron Kelly's bottom end and valvetrain was pretty typical on the Saurino car, but a lot of development on the cylinder head and exhaust took that engine well past where Comptune was with it.



That simply isn't true. I would wager that the Saurino/Aaron Kelly engines make no more hp than the last of the Dave Tabor Comptune motors.

As for dinging Rick on not finishing in his first outing this year, remember he lead the field at Mid-O (not the runoffs) last year until Campbell punted him off, so the old boy still has it in him to compete. I think few people who've not actually tried to build/develop/and drive their own car appreciate what a complex task it is. Everything new is a potential source of failure - as Rick found out at VIR.

You can choose not to like him, but you're only fooling yourself if you don't think he's paid his dues many times over in this sport/hobby/ obsession.

Dave Brown

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#13862 - 05/09/17 09:07 PM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: dcb]
hoffman900 Offline
Champion

Registered: 02/03/11
Posts: 542
Loc: New Jersey
Originally Posted By: dcb
Originally Posted By: hoffman900
Aaron Kelly's bottom end and valvetrain was pretty typical on the Saurino car, but a lot of development on the cylinder head and exhaust took that engine well past where Comptune was with it.



That simply isn't true. I would wager that the Saurino/Aaron Kelly engines make no more hp than the last of the Dave Tabor Comptune motors.


I think nostalgia has a way with things. No doubt Tabor was king of his era, but it's been almost twenty years... Even someone has legendary as the late Grumpy Bill Jenkins', his last great engines are relegated to backmarker status as time marches on in the professional drag racing world. That's just what happens.

And there is more to it than peak. wink

Originally Posted By: dcb

You can choose not to like him, but you're only fooling yourself if you don't think he's paid his dues many times over in this sport/hobby/ obsession.

Dave Brown



I never said or think that - it's clear he has, but it's also clear he isn't having fun. I also know you're his friend.

IMO, he should just stay quiet and get the car working well (Road America Runoffs wasn't a good showing, Mid Ohio last year he was pretty inconsistent outside of Charlie, and VIR this year seemed to be a disaster for him), no amount of complaining about transparency and roll cages is going to make for race finishes.

I know it probably chaps his ass to say, but Huffaker gave him a target at Mid Ohio to strive for lap time and consistency wise.



Edited by hoffman900 (05/09/17 09:14 PM)

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#13865 - 05/10/17 12:01 AM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: hoffman900]
dcb Online   content
Legend

Registered: 01/24/11
Posts: 1000
If I remember correctly, Fordboy has flow tested a lot of A-series heads and Tabor still probably has the best FP legal flow numbers. I'm also relatively sure that the Tabor HL cam is still a winner, so it's not nostalgia, it's reality that prompts me to say his stuff is still probably a top combination for FP A-series engines.

I suppose if you can find a way to keep valve springs and lifters intact, one of the high-energy cams that Fordboy likes will make more power, but you still probably won't find a better head. The reason is simple, I don't think you'll find anyone who spent more time intelligently developing and finessing these heads than Tabor.

The really unfortunate thing about comparing these engines is that dyno numbers mean nothing unless their all tuned on the same dyno. Most of the numbers are promotional and not really down to earth honest. So we use the track to compare and that too is pretty unsatisfactory - too many variables other than the engine are involved in lap times. I'm pretty sure that the big moment at Laguna for the Saurino car was more a result of Huffaker having a soft motor, and the fact that talented youth has advantages.

I talked a little about hp with Steve Sargis this last weekend. His numbers sort of indicate that there is a lot of inflation in some other's claims. Steve's numbers are modest, but no one seems to be able to best his records.

In the end I think we're talking about some very finite numbers with hard ceilings given the rule sets that need to be adhered to and the basic design of the components we have to use. The best outcome is probably more about broadening than peaking. And is most likely achieved by having components that are a good match for each other rather than a magical new discovery.

I hope to have one of those motors before the season is over.

Dave Brown

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#13872 - 05/10/17 03:54 PM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: fordboy628]
JohnJ Offline
Wannabe

Registered: 05/31/14
Posts: 5
Loc: NC
The Engine with the Comptune head made peak hp at 6700 and pulled to 7000 where it ran out of breath, it made peak torque at 5400. The engine with the new head made peak hp at 6800 and pulled to 7900, it made peak torque at 5700. At 6800 it was making 6 hp more than the Comptune and ended up at 10 more than the CT max. Doesn't sound like big differences but have to remember I am talking about a little 1275 vs a big V8.
John

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#13873 - 05/10/17 06:18 PM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: fordboy628]
Hap Waldrop Offline
Champion

Registered: 02/03/11
Posts: 781
Loc: Greenville, SC
What Comptune are we talking about, there are three eras, Dave Sr., Dave Jr., and then Mike Miller.
_________________________
Hap Waldrop
Acme Speed Shop 864-370-3000
www.acmespeedshop.com
MG/Triumph Performance Street/Race Engines
The Vintage Production Car Festival
https://www.facebook.com/vintageproductioncarfestival

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#13876 - 05/10/17 09:36 PM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: Hap Waldrop]
hoffman900 Offline
Champion

Registered: 02/03/11
Posts: 542
Loc: New Jersey
Originally Posted By: Hap Waldrop
What Comptune are we talking about, there are three eras, Dave Sr., Dave Jr., and then Mike Miller.


I'm talking about the Tabor years.

Originally Posted By: JohnJ
The Engine with the Comptune head made peak hp at 6700 and pulled to 7000 where it ran out of breath, it made peak torque at 5400. The engine with the new head made peak hp at 6800 and pulled to 7900, it made peak torque at 5700. At 6800 it was making 6 hp more than the Comptune and ended up at 10 more than the CT max. Doesn't sound like big differences but have to remember I am talking about a little 1275 vs a big V8.
John


John,

That doesn't surprise me. I can think of one or two things in regards to the peak power rpm being the same - which would be the cam.

What I think is going on, is the new head has way better velocity control than the old CT one. Flow isn't separating (likely over the short turn) and it is sized very well so there aren't any choke conditions occurring, thus allowing the power to hold on much longer.

Have to figure 6bhp at peak on a 140bhp engine is 4% gain. As the CT head falls off and the new head doesn't, that turns into a 7% gain. Not a bad figure. Likely you have about that much left in the exhaust system wink.



Edited by hoffman900 (05/10/17 09:38 PM)

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#13880 - 05/11/17 04:33 AM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: fordboy628]
fordboy628 Offline
Professional

Registered: 06/30/14
Posts: 311
Loc: NE Illinois
Guys,

I have a lot to say about the last 7 postings on this thread, but no time for the next couple of days.

Aaron has been very close mouthed about the head flow and bhp numbers about the Saurino engines. Since I have not seen the dyno numbers or the head flow numbers, there is no way to intelligently comment about them, except to say this: The National Championship winning engine obviously had "competitive" bhp, no more, no less. I think Aaron did a professional job that he can be proud of. And I would invite him to comment further here.

And let me remind everyone once again, that engines are complicated bits of machinery where every part interacts with all the other parts. Parts must be "systemized" to "work" together to obtain the best results. The cylinder head is not the only component at play to "satisfy" flow demand.

There is a rumor that a racer who frequents this board purchased a BMC head assembly from Aaron. Perhaps he can enlighten us about how it turned out on his engine.

And finally, I've been doing this a long time. I have yet to meet a person who can "violate" the rules of physics, or puts on their pants on with more than 1 leg at a time . . . . . .

grin

Cheers
_________________________
Fordboy628

Without "data", you are just another guy with a theory or an opinion . . . .

Someone who thinks logically is a nice contrast to the real world . . . .

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#13881 - 05/11/17 06:27 AM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: fordboy628]
fordboy628 Offline
Professional

Registered: 06/30/14
Posts: 311
Loc: NE Illinois
I have a few minutes for another quick thought.

There is a LOT of talk, and a LOT of hype about dyno numbers. A few facts:

A/ Water brakes are a NEARLY 100% efficiency. This depends a lot on the design and CONDITION of the brake. Data accumulation COMPENSATES for this with a numerical multiplier. This "multiplier" may or may not be correct.

2/ Let's face it, big numbers impress customers and sell engines to those uninformed about how power is measured and rated.

d/ I see and analyze a LOT of data. It is unlikely, nay impossible, for your carburetor 4 cylinder SCCA/Vintage engine to produce output/efficiency numbers that exceed those produced by engines in Professional racing series. You just don't have the budget. This is not to say the output can not be respectable or professional. Data that exceeds the stated parameters is, in my opinion, SUSPECT. Further investigation on these exact issues has ALWAYS proved me correct.

z/ The final arbiter is, as always, lap time/finishing order. I have seen many instances of "supposed" lesser bhp engines, "blow off" the engines with the "big numbers". And we are not going to debate driver ability here, it is out of the equation for this discussion.


There are only 2 things that can be said for certain about shops that have one dyno, that typically gets little maintenance and limited calibration:

1/ If the dyno you are using can not accurately repeat back to back runs, your data is: worthless.

2/ Even repeatable dynos are only useful for comparisons on THAT dyno.

Cheers
_________________________
Fordboy628

Without "data", you are just another guy with a theory or an opinion . . . .

Someone who thinks logically is a nice contrast to the real world . . . .

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#14063 - 07/23/17 12:47 PM Re: RACING ENGINES, A TECHNICAL EXAMINATION [Re: fordboy628]
fordboy628 Offline
Professional

Registered: 06/30/14
Posts: 311
Loc: NE Illinois
Some reality about certain 4 cylinder racing crankshafts.

OK, there has been a lot of discussion on another thread about engine failures in general, and crankshaft failures in particular. I'd like to shed a bit of "sunlight" on this complex subject.

1/ 4 cylinder, 4 stroke INLINE crankshafts have a secondary imbalance inherent in the design of the crank. This exists because the engine is "inline", such as a BMC 'A' series, and different from say an opposed 4, such as a VW. This is basic physics and no one can change that. More specific information on balance factors can be found in Volume 2 of "The Internal Combustion Engine in Theory and Practice", by Charles Fayette Taylor. This collegiate level engineering text is on my reading list for those who wish further info.

2/ 4 cylinder engines, racing or otherwise, typically combat this secondary imbalance with several strategies:

A/ Tuned "dampers" attached to the nose of the crank,
B/ Addition of mass, in the form of additional counterweights, or heavy flywheels, etc,
C/ Shorter stroke, or additional main bearings add support, if feasible,
D/ Superior materials, construction and treatment/finishing.

Depending on the engineer/designer/engine type/costs, all or none of these strategies might be employed.

Using the forum's favorite engine engineering example, the BMC 'A' series 1275cc, I have several thoughts, which I will share in no particular order. A "brain dump" if you will. I'll also preface these thoughts by stating that this is my opinion. Other engine professionals may or may not agree with my assessment of what is important . . . . .

*This engine design uses a stroke of 3.200". This is almost the stroke of a 327 Chevy V8, 3.250" The BMC uses 3 mains, 4 counterweights, the Chevy uses 5 mains and 6 counterweights.

*The stock 1275 BMC crank has been manufactured in various materials, some better than others. Same for the Chevy.

*Both engines in stock form utilize a "harmonic damper", instead of just a "balancer".

*Cosworth BDD's, a "full race" engine with a stroke of 3.055"and 5 mains, uses an 8 counterweight, billet EN40B, crank. That is no accident. The stock Ford 1600, on which the BDD is based, uses 5 mains, 4 counterweights and various cast and forged cranks . . . . .

*Also important to consider is the rpm range intended for both peak TQ and peak BHP. Service life (maintenance intervals) are also quite important.

*And, of course, the higher the rpm range, the higher the resultant forces. Asking any stock crank to withstand the forces of almost double the originally intended/designed rpm range seems "optimisty" to me.

*Using Hap's example of "wedging" stock cranks, I'd agree that it is a lot of machine work. Removing this material reduces the mass, I'm not sure this is a good idea in the case of the BMC. It also lowers the rotating moment of inertia, which is good for acceleration of the engine, AS LONG AS IT DOES NOT COMPROMISE RELIABILITY. I think it is a lot of work for what is gained, JMO.

*Using the SwifTune "Ghost Main" crank that DCB likes as an example, this increases MOI, but adds stiffness. On SwifTune built engines I have seen, the damper is eliminated. Not sure why Nick does that, but the design and improved material spec obviously allow it to work. No information on expected crank life is available as far as I am aware. I am also uncertain whether this type of crank is legal for SCCA F/Production.

*For Winston Cup Chevy V8 engines of 3.250" approximate stroke, where the "life expectation" is 700/800 miles, the very best materials, manufacturing and finishing are used, including expensive coatings, etc. They also add 2 counterweights to the center of the crank, for a total of 8 . . . . .

*What should be obvious is that this issue is complex, and the end user needs to consider what THEIR priority is, say extended crankshaft life of an expensive part Vs lowest moment of inertia for the fastest acceleration Vs ?????

Racers who are unable to make these types of judgments and choices should consult with experienced engineers and engine builders before plunking down their hard earned cash on expensive parts.

Gives you something to think about . . .

Please do me a favor and post any thoughts/responses about this on Dave's thread. It has a higher readership and therefore is more likely to be seen by others. Thanks.

Cheers


Edited by fordboy628 (07/23/17 05:56 PM)
_________________________
Fordboy628

Without "data", you are just another guy with a theory or an opinion . . . .

Someone who thinks logically is a nice contrast to the real world . . . .

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