Larry Meaux has been quietly porting heads and building championship winning race engines for more than three decades. A long list of winning customers is testament to his porting and engine design skills. He is passionate about race engine performance and leaves no stone unturned when investigating and testing new theories. In this interview he has devoted considerable time to answering our questions and sharing valuable knowledge that will help other racers and engine builders. Be sure to read the entire interview. It's long, but Larry shares some great porting tips that you can apply at home. In our opinion any engine you might contemplate should be modeled in his PipeMax program to determine optimum lengths and cross sections for intake and exhaust flow paths. Get a copy of PipeMax and join the forum on Larry's web site www.maxracesoftware.com for some eye opening information on race engine performance. Larry's years of experience have made him a valuable resource for engine builders seeking to optimize power and torque in racing engines. Now he's willing to share it with you.
Larry thanks for making some time to answer our questions. Please tell our readers a little about yourself and your company, i.e. how long you’ve been porting heads, how many you do in a year, who uses them, some of your success stories and so on. A brief bio if you will. Then we’ll get into the specific questions.
Meaux is pronounced like "Moe" (Cajun French pronunciation). Usually people have a hard time pronouncing my last name correctly so I just dropped the "e" and the "u" out of Meaux to form just the "Max" in MaxRaceSoftware to make it easier to pronounce and remember.
I started Meaux Racing Heads in July 1972 and have been porting heads and manifolds ever since. I purchased my first flow bench in February 1978. It was the SuperFlow SF-110 Bench and in May 1984 I purchased the higher capacity SF-600 flow bench from SuperFlow. In December 1987 i purchased the SuperFlow SF-901 engine dyno.
Machine Shop equipment includes:
- Storm Vulcan 85B-E Block Master
- Stewart Warner Industrial Balancer
- Kwik-Way FN Boring Bar + custom made block O-ring receiver groove cutter
- Kwik-Way VS Valve Grinder + custom made .0001" accuracy valve Chuck capability
- Peterson Head Shop, Air float table
- Miller Dial Arc 300 amp Tig welder
- Vertical Mill with Head Fixture plus various Goodson 3D Valve seat Cutters and tooling, various BHJ, Sunnen valve guide plus block hone, fixtures, Rimac Marquette Distributor Machine, etc.
Billy Carter's 441ci Small Block
Craig Bourgeois' A/NS Dragster
Jeff Colletta's NPS Camaro
John Wilson's 440ci Chevelle
Since the 1980s to present day my customers have set 34 NHRA National Records in various classes such as NHRA Stock, Super Stock, and Competition Eliminator along with numerous wins in Dirt Track racing, Mud Truck racing, Boat racing classes and even a IMSA pole position at Houston one year.
Now that there are so many good CNC ported heads on the market, how much can they be improved by a knowledgeable head porter and is hand porting still a viable option?
Years ago when CNC ported heads first became popular I'm sure there were many head porters like myself that thought our future looked bleak, but now there are so many more new head porters as well as many new shops specializing in CNC'ing heads it appears we can coexist profitably together.
Cylinder Heads are still a casting, which can have some core shift or mold setup irregularities. I've seen CNC'd heads where there are areas inside some of the ports that were not touched by the CNC cutter. Some of this depends on the casting accuracy and some of the errors depend on the person setting up the head in the CNC fixture and of course the accuracy of the fixture itself.
The older style heads like the small block Ford, Chrysler, and 23 degree Small Block Chevys have difficult short turn curves for a CNC machine to get in there and mill properly to the correct curve shape. So far, I have been very successful in gaining more horsepower and torque by further hand-porting heads that were previously CNC'd.
BBC Dart Olds 14-deg. Oval Port
BBC Dart Olds, 14-deg.valve seat blending
BBC Dart Olds, 14-deg. exhaust port
BBC Dart Olds 14-deg, guide blending
Another example of hand-porting versus CNC would be my customers in the NMCA Nostalgia Pro Street Class. We won the NMCA Nostalgia Pro Street Championship in 2007, 2010, and 2011 and we are now leading the 2012 points with one race left to go. All four of these various BBC 632-640 cubic inch engines were initially dyno and dragstrip tested with those heads as they came with each Manufacturer's best CNC job. Then I further hand-ported those same heads, changed the port and chamber shape, the valve job and short turn curve shape; all responded with gaining 80 to 100 HP (engine gains only, no NOS dyno tests, much higher gains when NOS was used!) as well as shifting entire torque and horsepower curves upwards by 300 to 500 RPM. Back on the dragstrip in hand-ported form, they set ET and MPH records, numerous #1 qualifying positions and won the Championships in those years.
But I have to admit in this last year the various CNC'd heads I've been receiving in the shop are much better in terms of port shape and in horsepower and torque gains. In fact just in last two weeks I received another manufacturer's best effort BBC NPS style CNC ported head that in my measuring was just about an exact copy of my best hand-ported 2012 NPS head. It’s like they were able to digitally copy my best port/chamber shape, yet I know that didn't really happen. It just shows you how quickly CNC porting is evolving. I'm glad I've branched off into computer programming and motorsports software. Those CNC guys are trying to put me out of the porting business. It’s very possible that even a good portion of CNC'ing may be replaced by Stereo-lithography or 3D metal printing in the future of motorsports.
Chrysler SS intake flow bench analysis
Plenum floor dam test
Flow test w/Q-jet carb
Plenum floor mods
There will always be money to be made by your typical head porting shop or machine shop. Things happen like engine blowups etc., and on CNC'd heads you might need to weld/grind repairs, redo valve jobs with Bowl and Chamber blending, re-flow tests, new valve guides or resurfacing etc., Or just plain hand-porting experimentation to improve or correct a particular CNC'd port.
One more observation about a CNC'd head versus a hand ported head is in the area of the valve job. The most critical part of the cylinder head performance wise, is the actual valve job area. With tooling such as Goodson 3D Cutters/Bodies the average machine shop or porting shop has the ability to exactly match the CNC machine in the critical valve job area and a little below in the bowl and little above in the chamber with the proper cutter profiles.
You pioneered the popular PipeMax software program. When did you first develop it and what motivated you to do it- and - how long did it take to compile the research and write the program?
In the early 1980's, one day my wife surprised me with a new Radio Shack Tandy color computer also known as the CoCo computer for which you used your TV set as the Monitor. It also came with a form of the BASIC programming language. I was instantly hooked on programming. Later on, I purchased a Tandy 286 computer that had GW-Basic language and began trying to correlate all my engine building and dragstrip testing data into software programs that would make it instantly quicker and easier to solve typical motorsports problems such as: How much horsepower does it take to run a certain ET or MPH? What is the engine RPM at the finish line with such and such rear gears or tire diameter, etc.? What's the cubic inch engine size or what's the compression ratio or the effects of rod length?
My first real programming effort was developing a Quarter Mile prediction simulation and at the same time developing an engine simulation program which was to be the start of the PipeMax program. I did manage to sell 4 or 5 copies of the Quarter Mile and Engine simulation programs, but they were .BAS files containing original source codes that you would run inside the GW-BASIC program. They had no Mouse support either and were on old 5 ¼-inch and 3.5-inch floppy discs.
I did realize that I can't be giving away the source codes along with those programs so that ended any further sales and I kept on gathering data and developing those programs until i could get my hands on a compiler to turn them into .exe programs. That happened around 1988 when I bought Microsoft's QuickBasic 4.5 which included a compiler to create exe programs, then later on Microsoft's PDS QuickBasic 7.1 with compiler and in 1992 Visual Basic for DOS 1.0 and for Windows 1.0 which by then I had about 4 years of SF-901 Dyno data and experience to create PipeMax 1.0 DOS and Windows versions for sale to racers. PipeMax in DOS versions went as far as 5.0 and now the current 2012 version of PipeMax for Windows is 4.0.
Now that it’s been out there a while and you’ve had a chance to get some feedback, what have you learned about your customers, how many are using it, who is using it and what they’re reporting about the results they are getting from the recommendations it provides. How well has it been accepted as an important engine building (planning) tool?
PipeMax has almost 3000 registered Users world-wide so far, and around 820 members in the PipeMax Forum. All the e-mail reports and posts on various Forums I've read have all been positive. The acceptance "as an important engine building (planning) tool?" has been better than I expected!
You point out that PipeMax is not a full on engine simulator, but it yields some pretty good predictions. Do you think the engine simulators out there today do a pretty good job of helping racers plan their engine projects?
PipeMax 1.0 to 3.7 versions were a "Predictor." You input engine data such as the engine's volumetric efficiency and the RPM at which peak horsepower occurred; then PipeMax would predict all the various engine specs, including header specs it would take to achieve your desired RPM and the level of horsepower and torque that matched up with your VE percentage input.
I'm currently working on two different versions of PipeMax 4.0; a predictor and a simulator. The new 4.0 version PipeMax Predictor now has enough user inputs to almost be an engine simulation program; however it’s still a Predictor and will calculate the engine specs needed to achieve the horsepower and RPM goal you input.
The new 4.0 PipeMax Simulator is an engine simulation program. It will calculate the horsepower and torque curves as well as the volumetric efficiency percentage and the RPM points they occur at instead of your needing to input that in the Predictor version. PipeMax Simulator is sort of the opposite of PipeMax Predictor.
Jim Jarrett 1782 HP 639cid
You’ve had some past winners at the Hot Rod Pump Gas Drags using your cylinder heads. Were any of those heads and inlet systems chosen and modified according to your PipeMax program.
In 2005 Ray Wilde's '95 Mustang with a small block Chevy engine had the fastest qualifying small block Chevy of the event and my other customer Charles Jordan's '87 Firebird had the 2nd fastest qualifying small block Chevy of the event.
In 2006 Charles Jordan's '87 Firebird had the fastest qualifying times of the entire event regardless of engine size or type, but lost out on the 3rd run due an NOS line bursting. Ray and Charles’ cylinder heads/manifold/engines plus their entire exhaust system were constructed to PipeMax specs.
Both Ray and Charles reported after the 2006 event they had approx 6 gallons of gas left in their tanks. Later I got to look at the intake ports and bowls on both of their heads. There was no evidence of exhaust reversion inside the intake bowls or ports and the intake bowls looked like the day I ported them.... that's pretty good evidence the exhaust system lengths and diameters PipeMax predicted were working great!
We like to stress application specific mods for any race engine, particularly when choosing inlet and exhaust flow path dimensions. How do you approach that when helping a customer choose the proper head for his application?
Meaux Racing dyno room
I use my 24-plus years and thousands of dyno testing experiences with various engine/cylinder-head/manifold/camshaft combinations to help choose the correct cylinder head for customers. To double-check myself or to help choose a combination I have no prior experience with. I’ll use PipeMax to get an idea what's needed. The newer PipeMax version 4.0 will calculate all the cylinder head port volumes for you if you input the port's centerline length and it will also calculate total induction volumes and cross-sectional areas as well as how much flow (CFM) heads are required to flow for your RPM range.I'll also use Performance Trend's Engine Analyzer, Motion Software's Dyno program and Patrick Hale's Engine Pro software to compare against what PipeMax is predicting to get a further idea what's required for a customer's engine combination.
If most of your customers are drag racers it follows that you’re mostly working with high rpm applications with relatively narrow power bands. Without giving too much away, are there any specifics you like to apply to these cases?
Using the dyno data into PipeMax and my ET Analyst quarter-mile simulation program I can tell how well the engine combination is doing versus the flow bench data and I can know what the ET and MPH times will be each foot distance down the quarter mile.
While the Engine is still on the Dyno I can run ET Analyst and know what RPM it should cross and the finish line, the best RPM shift points, what RPM it should fall back to on the gear change and then make changes on the dyno to enhance the torque and horsepower curve in those RPM ranges. I will also know best rear gears or transmission gears to use, what tires to use, how much converter stall to use, etc. When the customer leaves the dyno, he will already know how fast he will go!
Also all that information is great to give your converter guy so he can give you the best possible converter for your combination. We use A1 converters a lot. They know my dyno very well and they are almost 100 % accurate with their first effort in building the best converter for the fastest ET and MPH.
You focus a lot on reducing reversion. In addition to proper camshaft selection, what do you do to the cylinder heads to help reduce reversion?
To reduce Mixture over-scavenging, exhaust side reversion at the overlap period, intake side reversion after BDC, like you mentioned the proper camshaft selection, but more importantly the proper intake and exhaust system lengths and diameters or cross-sectional areas as well as port shapes.
If you wanted to combat reversion effects with just cylinder head mods you can reduce intake valve margin thickness to around .020-inch to .040-inch and also not use a valve back cut on either the intake or exhaust valves, which will make the intake and exhaust valves sort of like a one-way valve flowing worse in the opposite reversion direction.
Use more tuliped shaped intake and exhaust valves especially at lower RPM ranges. Sink the valve job enough to get at least a full .100-inch wide top angle width above the valve seat angle.
Keep throat diameters in the .85% to .88% range (of valve size).
Use sharp multi-angle intake seat angles, no intake radius valve job and no valve back cuts.
It’s very important to use cylinder heads with a port shape and cross-sectional area that maintains high enough gas velocity in your desired RPM range to combat reversion effects.
Use combustion chamber wall shape around the intake valve to maintain mixture velocity and mixture direction through the transition from port to bowl to valve job and on through the chamber to fight against flow reversing piston motion effects.
How much attention do you pay to intake runner taper and what can you tell our readers about its contribution to cylinder filling?
All the older and latest cast manifolds I've seen have taper in them; that is, a much larger plenum runner entry area as compared to intake gasket opening area. Large amount of taper can have another advantage effect on a single-plane manifold by allowing a larger turn radius into the runner from the bottom of the carb throttle bores. This can keep the mixture from slamming so much into the plenum floor and can result in more equal fuel distribution. Taper can also reduce the manifold's flow restriction to the cylinder heads. And it can also benefit by reducing reversion waves in instances where the plenum volume might be too small. However, excessive taper can kill torque and even kill higher RPM horsepower! This was very horsepower and torque evident in dyno testing various fuel Injector taper angles and length combinations.
What advice would you give an engine customer looking to purchase a set of heads for his race car?
Some customer's are "Brand loyal", they prefer a certain manufacturer's head over everyone else. Sometimes the brand they love is not the best cylinder head for them. I always try to steer the customer toward the best cylinder head or manifold no matter what brand the Manufacturer may be.
Does it make much sense to do much porting work on iron heads? A lot of head porters won’t touch them.
The only thing I like about porting cast-iron heads is that in the process of porting them you are not creating shavings that are needle points. Aluminum head shavings are like needles that stick in your skin, get inside your shoes or boots, or in your eyes. Aluminum shavings also burn your flesh longer as they are hotter longer than cast-iron shavings.
Cast-iron shavings create more iron dust so a good protective breathing mask is absolutely necessary. The worst thing about cast-iron heads is that they crack and it’s very hard and expensive to repair them after they crack!
The second worse thing about cast-iron heads, especially big block Chevy aftermarket heads, is the weight of those Heads! In the process of porting those type heads, I might turn or flip the heads on my porting bench around 50 to 100 times in various positions. After all the many hours of porting on them, my wrists, neck, shoulders, and lower back take a beating! Another bad thing about cast-iron heads is it takes much longer to grind away the necessary amount of metal. Aluminum is much faster and requires less effort to port.
The only racing classes where I see an actual need and useful purpose in using a cast-iron head is for classes like NHRA's Stock and Super Stock. In every other type of racing there should be no mandatory need or use for any type of cast-iron heads. It costs way more money overall to use and maintain cast-iron heads in any form of motorsports than it does aluminum heads! A "cast-iron only head" rule is in no way a cost effective racing rule!
Just think of the world-wide impact of using heavy cast-iron heads on all the foundry workers , on all the head porters, and on all the UPS or FedX drivers/workers that have to deal with the heavier weight of cast-iron heads.
Do you have any recommendations for the budget conscious guy trying to port his own heads?
If you don't own a flow bench or have access to a flow bench when porting your heads, then grind just enough short turn curve material to create a nice gentle curved transition. Make all your grinding mods into nice gentle turning and blending shapes. Keep the intake throat diameter in the .86% to .88% range, and the exhaust throat diameter in the .85% to .87% range.
Don't hog out the intake port entry or the exhaust port exit; instead look inside the Ports for the smallest cross-sectional area and moderately or slightly enlarge those areas, always being aware you could grind too much and break thru the casting into a water jacket or thru outside the wall. Study the inside of the water jacket areas to get an idea how thick a port wall is or isn't.
If you do own a flow bench, then purchasing a Pitot Probe would be a super wise investment! You want a J-style or 180 degree Pitot Probe shape for the intake ports and a long turn 90 degree Pitot for the exhaust ports.
What are the most common mistakes you see racers do to their cylinder heads and induction systems?
- Hogging out all the ports as large as they can with no regard to necessary cross-sectional area
or correct port shape. Things like making the exhaust port as large as the Header tube or grinding the intake ports to the largest available intake gasket size.
- Other mistakes include grinding all the intake ports, exhaust ports, and combustion chambers to a mirror finish. Likewise for a mirror finish inside the intake manifold.
- Breaking out thru a water jacket or casting wall, then having to go back and epoxy that area or weld back material.
- Not using a Pitot Probe for testing!
- Large straight cut surface milling their Heads to reduce chamber CC's, instead of angle-milling heads.
- Milling intake manifold sides to make the Intake Manifold fit the heads on the block!
Never mill the intake manifolds sides to fit; instead always mill the intake side of the cylinder heads.
Only mill the front and rear gasket rails of the intake manifold if you need to, however the block's rails
should have been milled instead for you.
- Spending all the money and effort on the cylinder heads and then bolting on an inferior intake manifold design.
Are there ever times when you treat individual ports differently to accommodate intake manifold oddities like long and short runners (BBC good port, bad port for example) or maybe an application where you might seek to broaden a torque curve by dividing the engine into two separate engines with different flow path dimensions chosen to achieve multiple torque peaks at different engine speeds?
Like your big block Chevy head example or like a Ford head, there's more difference in the intake manifold runner lengths for those type heads than the difference in the ports!
The differences in the intake manifold runner lengths can broaden the Torque curve, similar effects as unequal length header primary pipes. Usually unequal length runner or pipe lengths will make less peak torque, but a wider torque or horsepower curve.
On the big block Chevy conventional head where you have a “Good Direction” port that flows more CFM and a “Bad Direction” port that flows less CFM many things have been tried in the past to make up those differences. Things like different rocker arm ratios, different cam lobes for the two different port shapes, different injector tube lengths, different header pipe diameters and lengths, different heat range plugs or jetting.
The "Good Direction” ports flow more on a flow bench, but their direction was aimed toward the open part of the chamber and toward the exhaust valve. During the overlap period it was possible to waste significant mixture right out the exhaust port.
The “Bad Direction” ports flow less on a flow bench because their direction was aimed at the more shrouded part of the chamber away from the exhaust valve. During the overlap period this port did not waste as much mixture out the exhaust port. The “Bad Direction” ports also have higher pressure recovery from BDC to intake valve closing point.
In my opinion the longer “Good Direction” ports ended up not being that good and the shorter “Bad Direction Ports” ended up not being that bad to the point where they sort of equaled out! They seemed to "trap" about the same amount of mixture inside the cylinders by IVC point.
Now days, you don't see many attempts to try and equal them out except for trying to get them to flow the same and to get their port lengths as nearly the same, but the two basic port directions remain the same in the conventional big block Chevy design.
The big block Chevy with conventional port design heads and a single-plane intake manifold is a mixture of port directions and total induction lengths!
Cylinder #1 is a long Good Port with a relatively straight short manifold runner length.
Cylinder #3 is a short Bad Port with a relatively straight short manifold runner length.
Cylinder #5 is a long Good Port with a more abrupt turning longer manifold runner length.
Cylinder #7 is a short Bad Port with a relatively better turn shape, longer manifold runner length and it’s all mirrored on the 2-4-6-8 cylinder side
It’s interesting to see that GM chose the Bad Direction port shape that aimed the intake port away from the exhaust valve like the big block Chevy, for their LSX type Heads and SB2 heads, a similar direction as what Ford did for years.
How do you feel about intake port texturing that attempts to achieve a similar effect to the CNC porting marks? Some people recommend using heavy grit cartridge rolls to texture the intake ports and the manifold runners. Any thoughts?
Textured combustion chamber
This was one of my Speed Secrets, but I've had to include and account for its effects in the new PipeMax version 4.0 to make it correlate with my new dyno and dragstrip data. In 2010 I talked my best engine building customers into letting me try something I've wanted to test for the last 30 years or so. I took one of my old chipped up and slightly bent Alumina Burrs and rough ground just the entire intake ports on a big block Chevy Dart head all the way to the bottom valve job angle cut. Back on the dyno the engine gained almost 15 HP on a 950 HP engine. You could theorize that the intake ports are slightly now larger and it should have made more horsepower.
We kept testing this on the next 5 or 6 various types and engine CID sizes, grinding over the previous 60-Grit finish with the rougher alumina burr finish and gaining anywhere from 10 to 15 HP and lower BSFCs and sometimes shifting Peak HP RPM point 100 or 200 RPMs higher.
Textured manifold runner
After those test results I talked another Engine Builder into trying out the rough carbide finish. That engine/car was previously tested on his chassis dyno as a baseline. I originally ported and polished the ports and chambers with 60-Grit finish in the baseline test. Next I rough carbide finished the intake and exhaust ports and chambers. Back on the chassis dyno it gained 17 rear wheel horsepower which is about 20-25 engine flywheel horsepower.
Again, I removed the heads and went back to 60-Grit finish everywhere. Back on the chassis dyno it lost the 17 horsepower and was basically back to where the engine was originally. That was the only A-B-A tests I've done so far. I wish those tests would have been on my engine dyno instead. We kept going with the rough carbide finish everywhere in the intake, exhaust ports, chambers and intake manifold from that point on. So far every engine has responded with 15-25-plus horsepower increases, a wider power curve, sometimes 100 to 300 higher RPM point of peak horsepower, less fuel consumed on the Dyno ( lower BSFCs ) and dryer exhaust ports.
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.
In 2011 Jim Jarrett won the NMCA NPS Championship with the rough carbide finish everywhere. In 2012 Dave Beeson set the NPS Record and is leading points with the rough carbide finish everywhere.
Danny Durand’s 1994 Beretta at 2450 lbs with 440cid, Dart Pro-1 23deg heads and 807 HP at 8300 RPM ran a best of 8.39 ET at 163 MPH motor only, with rough carbide finish everywhere. 7.493 ET at 186.36 MPH with 325 HP NOS kit.
A couple of weeks ago we just finally made over 900 HP with All Pro 23deg heads on a 440cid SBC at 8300 RPM on Billy Carter's heads and manifold with rough finish everywhere. Those are just a few examples of what the rough carbide finish is doing.
To achieve that rough carbide finish, I use a 6 inch long shank slightly bent Alumina Burr with chipped teeth in an Air Grinder turning a certain RPM with a certain load force against the port or chamber walls, all the while keep the air grinder as loose as possible in my hands, but still with full accurate control in grinding. You cannot use an electric grinder; it must be an air grinder. It’s ugly and unimpressive to look at, but it’s definitely faster down the dragstrip!
Just a few days ago we dyno tested a BBC 588cid engine with a newer much rougher finish everywhere in the chambers and 1 inch down in the bowls; everywhere else the ports are still like the old rough carbide finish. On the Dyno it made another 10-plus peak horsepower and shifted the RPM point of peak horsepower 200 RPMs higher with completely bone dry exhaust ports.
The new carbide burr is a 6-inch long shank. I slightly bent and worked the carbide burr against steel bar to lightly chip up a few teeth edges and it also has lesser number of teeth and definitely needs to be in an Air Grinder. It has to be held and worked just right but it leaves a rough almost harpoon edge effect finish that will slightly grab your skin as you run your finger across it. More Dyno tests on this newer finish are yet to come.
Jim McFarland has been pushing this concept for as long as I’ve known him. I suspect the increased texturing is promoting better mixture quality due to less fuel separation and finer droplets that burn more efficiently. Improve mixture quality delivers the power increase and combined with the ever so slight port cross-section enlargement raises the rpm level of the power curve. You think?
My Dyno tests so far show around a maximum gain of .018% times Peak HP as the typical HP gain from a rough carbide finish everywhere including the Intake Manifold. The majority of the tests were with VP's Q-16 race gas, the rest of the tests were with VP C23, C25 , C16, and Exxon 93 premium. I agree with Jim McFarland; it appears to be trapping a greater amount of higher quality mixture by IVC point and also burning it more efficiently during combustion.
How much stock do you place in flow bench work and/or wet flow bench analysis?
I've done some wet-flow and swirl tests many years ago and even combinations of wet-flow with swirl. I then purchased Quadrant Scientific's Swirl Torque Meter, and it verified many of the test and swirl patterns I was seeing. "How much stock do you place in flow bench work?"
The Flowbench is my "Eyes"! Everything is see on the flow bench as far as gains, including Pitot Probing, shows up on the dyno and every gain I see on the dyno shows up down the dragstrip! My SuperFlow SF-901 Dyno has a very good reputation in my area for being HP conservative and for every dyno horsepower and torque gains actually showing up down the dragstrip.
Do you do much head repair work, or is it usually best to start over with a new head if a customer has damaged a head?
I do very minor cylinder head weld repairs. Anything like a major welding repair, I send off to better welding experts. If the head’s in pretty bad shape, I'll talk the customer into purchasing a new replacement head.
Do you have any recommendations regarding port and gasket matching and manifold modifications to alter the entry angles?
From flow bench and dyno testing there can be a bunch of horsepower gained by straightening up the manifold or injector angle to the head's intake port angle. I’ve gained a lot of horsepower doing this on B/ND 23deg type heads trying to better match up injector tube angle to intake port angle. Likewise a few times we have had to redo sheet metal manifolds to correct the angle transition and gained horsepower and torque.
What’s your feeling about matching carburetor or throttle body sizing to an engine based on application, engine size and rpm. How does PipeMax deal with this?
This can be a pretty good area to gain horsepower and torque. PipeMax does calculate the required Carb CFM for your Engine. I also try to always measure plenum vacuum during dyno testing. On single-plane manifolds, anything over 1.2" Hg vacuum is too restrictive and a lot of times an engine will make its best overall horsepower and torque combination at 0.7" Hg vacuum. Great straight-shot tunnel ram mutli-carb manifolds can make their best horsepower and torque with only 0.5" Hg vacuum.
How closely do you consider carb size and plenum size in relation to porting and cylinder head matching?
Very important. Again I just use PipeMax to calculate what carb size I need and get an idea of the plenum volume needed. Current version 3.7 PipeMax is very accurate in determining minimum plenum volume required and I'm working on newer version 4.0 which should be just as accurate in calculating the maximum required plenum volume and a recommended plenum volume.
PipeMax draws heavily from wave tuning theory. Have you gathered enough comparison data to match theory and practice to the point where predictable results are easily demonstrated?
It’s always fun and amazing to see the dyno customer's expression when I add to his collector length to make it match up to PipeMax’s prediction and watch it make a bunch more torque and horsepower on the next dyno test! This is especially noticeable on dyno customers’ engines that are in the 3000 to 6500 RPM ranges and that have typical off the shelf street or strip headers that have collector lengths that are way too short.
We make at least 5 to 8 dyno pulls and get the engine in the ballpark as regards to ignition timing and jetting etc., and then I'll run the entire engine and dyno data into PipeMax inputs and see how well it’s matching up. Then I calculate what the header specs should be, adjust collector length to one of the best harmonics or sometimes I'll completely change out to better set of headers and make another few dyno pulls to show customers the differences and effects.
Gains from proper collector sizing
It’s not uncommon to gain 60-plus horsepower to as much as 140-plus horsepower with the correct header specs and collector length on low compression ratio and low RPM range engines, especially with too much duration and overlap period.
Using SuperFlow's air turbine to measure the VE percentage rate of climb and CFM easily shows up incorrect exhaust system lengths. The air turbine is also useful in showing valve float.
Well thanks a bunch Larry. You have been very informative and forthcoming about your head porting procedures and engine testing results. Perhaps we can talk more after you’ve had more time to evaluate different port textures and their effects on power.
Readers who enjoyed this article are encouraged to visit www.maxracesoftware.com to get the inexpensive the PipeMax program and join the tech forum. It’s surprisingly affordable for the quality of information it provides and it pretty clear from this interview that Larry has put a tremendous amount of work and study into developing it. There’s no way you can beat it for sound engine planning with predictable results.
Meaux Racing Heads