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Why the Ford Pinto didn’t suck

Why the Ford Pinto didn't suckThe Ford Pinto was born a low-rent, stumpy thing in Dearborn 40 years ago and grew to become one of the most infamous cars in history. The thing is that it didn't actually suck. Really.

Even after four decades, what's the first thing that comes to mind when most people think of the Ford Pinto? Ka-BLAM! The truth is the Pinto was more than that — and this is the story of how the exploding Pinto became a pre-apocalyptic narrative, how the myth was exposed, and why you should race one.

The Pinto was CEO Lee Iacocca's baby, a homegrown answer to the threat of compact-sized economy cars from Japan and Germany, the sales of which had grown significantly throughout the 1960s. Iacocca demanded the Pinto cost under $2,000, and weigh under 2,000 pounds. It was an all-hands-on-deck project, and Ford got it done in 25 months from concept to production.

Building its own small car meant Ford's buyers wouldn't have to hew to the Japanese government's size-tamping regulations; Ford would have the freedom to choose its own exterior dimensions and engine sizes based on market needs (as did Chevy with the Vega and AMC with the Gremlin). And people cold dug it.

When it was unveiled in late 1970 (ominously on September 11), US buyers noted the Pinto's pleasant shape — bringing to mind a certain tailless amphibian — and interior layout hinting at a hipster's sunken living room. Some call it one of the ugliest cars ever made, but like fans of Mischa Barton, Pinto lovers care not what others think. With its strong Kent OHV four (a distant cousin of the Lotus TwinCam), the Pinto could at least keep up with its peers, despite its drum brakes and as long as one looked past its Russian-roulette build quality.

But what of the elephant in the Pinto's room? Yes, the whole blowing-up-on-rear-end-impact thing. It all started a little more than a year after the Pinto's arrival.

 

Grimshaw v. Ford Motor Company

On May 28, 1972, Mrs. Lilly Gray and 13-year-old passenger Richard Grimshaw, set out from Anaheim, California toward Barstow in Gray's six-month-old Ford Pinto. Gray had been having trouble with the car since new, returning it to the dealer several times for stalling. After stopping in San Bernardino for gasoline, Gray got back on I-15 and accelerated to around 65 mph. Approaching traffic congestion, she moved from the left lane to the middle lane, where the car suddenly stalled and came to a stop. A 1962 Ford Galaxie, the driver unable to stop or swerve in time, rear-ended the Pinto. The Pinto's gas tank was driven forward, and punctured on the bolts of the differential housing.

As the rear wheel well sections separated from the floor pan, a full tank of fuel sprayed straight into the passenger compartment, which was engulfed in flames. Gray later died from congestive heart failure, a direct result of being nearly incinerated, while Grimshaw was burned severely and left permanently disfigured. Grimshaw and the Gray family sued Ford Motor Company (among others), and after a six-month jury trial, verdicts were returned against Ford Motor Company. Ford did not contest amount of compensatory damages awarded to Grimshaw and the Gray family, and a jury awarded the plaintiffs $125 million, which the judge in the case subsequently reduced to the low seven figures. Other crashes and other lawsuits followed.

Why the Ford Pinto didn't suck

Mother Jones and Pinto Madness

In 1977, Mark Dowie, business manager of Mother Jones magazine published an article on the Pinto's "exploding gas tanks." It's the same article in which we first heard the chilling phrase, "How much does Ford think your life is worth?" Dowie had spent days sorting through filing cabinets at the Department of Transportation, examining paperwork Ford had produced as part of a lobbying effort to defeat a federal rear-end collision standard. That's where Dowie uncovered an innocuous-looking memo entitled "Fatalities Associated with Crash-Induced Fuel Leakage and Fires."

The Car Talk blog describes why the memo proved so damning.

In it, Ford's director of auto safety estimated that equipping the Pinto with [an] $11 part would prevent 180 burn deaths, 180 serious burn injuries and 2,100 burned cars, for a total cost of $137 million. Paying out $200,000 per death, $67,000 per injury and $700 per vehicle would cost only $49.15 million.

The government would, in 1978, demand Ford recall the million or so Pintos on the road to deal with the potential for gas-tank punctures. That "smoking gun" memo would become a symbol for corporate callousness and indifference to human life, haunting Ford (and other automakers) for decades. But despite the memo's cold calculations, was Ford characterized fairly as the Kevorkian of automakers?

Perhaps not. In 1991, A Rutgers Law Journal report [PDF] showed the total number of Pinto fires, out of 2 million cars and 10 years of production, stalled at 27. It was no more than any other vehicle, averaged out, and certainly not the thousand or more suggested by Mother Jones.

Why the Ford Pinto didn't suck

The big rebuttal, and vindication?

But what of the so-called "smoking gun" memo Dowie had unearthed? Surely Ford, and Lee Iacocca himself, were part of a ruthless establishment who didn't care if its customers lived or died, right? Well, not really. Remember that the memo was a lobbying document whose audience was intended to be the NHTSA. The memo didn't refer to Pintos, or even Ford products, specifically, but American cars in general. It also considered rollovers not rear-end collisions. And that chilling assignment of value to a human life? Indeed, it was federal regulators who often considered that startling concept in their own deliberations. The value figure used in Ford's memo was the same one regulators had themselves set forth.

In fact, measured by occupant fatalities per million cars in use during 1975 and 1976, the Pinto's safety record compared favorably to other subcompacts like the AMC Gremlin, Chevy Vega, Toyota Corolla and VW Beetle.

And what of Mother Jones' Dowie? As the Car Talk blog points out, Dowie now calls the Pinto, "a fabulous vehicle that got great gas mileage," if not for that one flaw: The legendary "$11 part."

Why the Ford Pinto didn't suck

Pinto Racing Doesn't Suck

Back in 1974, Car and Driver magazine created a Pinto for racing, an exercise to prove brains and common sense were more important than an unlimited budget and superstar power. As Patrick Bedard wrote in the March, 1975 issue of Car and Driver, "It's a great car to drive, this Pinto," referring to the racer the magazine prepared for the Goodrich Radial Challenge, an IMSA-sanctioned road racing series for small sedans.

Why'd they pick a Pinto over, say, a BMW 2002 or AMC Gremlin? Current owner of the prepped Pinto, Fox Motorsports says it was a matter of comparing the car's frontal area, weight, piston displacement, handling, wheel width, and horsepower to other cars of the day that would meet the entry criteria. (Racers like Jerry Walsh had by then already been fielding Pintos in IMSA's "Baby Grand" class.)

Bedard, along with Ron Nash and company procured a 30,000-mile 1972 Pinto two-door to transform. In addition to safety, chassis and differential mods, the team traded a 200-pound IMSA weight penalty for the power gain of Ford's 2.3-liter engine, which Bedard said "tipped the scales" in the Pinto's favor. But according to Bedard, it sounds like the real advantage was in the turns, thanks to some add-ons from Mssrs. Koni and Bilstein.

"The Pinto's advantage was cornering ability," Bedard wrote. "I don't think there was another car in the B. F. Goodrich series that was quicker through the turns on a dry track. The steering is light and quick, and the suspension is direct and predictable in a way that street cars never can be. It never darts over bumps, the axle is perfectly controlled and the suspension doesn't bottom."

Need more proof of the Pinto's lack of suck? Check out the SCCA Washington, DC region's spec-Pinto series.

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My Somewhat Begrudging Apology To Ford Pinto

ford-pinto.jpg

I never thought I’d offer an apology to the Ford Pinto, but I guess I owe it one.

I had a Pinto in the 1970s. Actually, my wife bought it a few months before we got married. The car became sort of a wedding dowry. So did the remaining 80% of the outstanding auto loan.

During a relatively brief ownership, the Pinto’s repair costs exceeded the original price of the car. It wasn’t a question of if it would fail, but when. And where. Sometimes, it simply wouldn’t start in the driveway. Other times, it would conk out at a busy intersection.

It ranks as the worst car I ever had. That was back when some auto makers made quality something like Job 100, certainly not Job 1.

Despite my bad Pinto experience, I suppose an apology is in order because of a recent blog I wrote. It centered on Toyota’s sudden-acceleration problems. But in discussing those, I invoked the memory of exploding Pintos, perpetuating an inaccuracy.

The widespread allegation was that, due to a design flaw, Pinto fuel tanks could readily blow up in rear-end collisions, setting the car and its occupants afire.

People started calling the Pinto “the barbecue that seats four.” And the lawsuits spread like wild fire.

Responding to my blog, a Ford (“I would very much prefer to keep my name out of print”) manager contacted me to set the record straight.

He says exploding Pintos were a myth that an investigation debunked nearly 20 years ago. He cites Gary Schwartz’ 1991 Rutgers Law Review paper that cut through the wild claims and examined what really happened.

Schwartz methodically determined the actual number of Pinto rear-end explosion deaths was not in the thousands, as commonly thought, but 27.

In 1975-76, the Pinto averaged 310 fatalities a year. But the similar-size Toyota Corolla averaged 313, the VW Beetle 374 and the Datsun 1200/210 came in at 405.

Yes, there were cases such as a Pinto exploding while parked on the shoulder of the road and hit from behind by a speeding pickup truck. But fiery rear-end collisions comprised only 0.6% of all fatalities back then, and the Pinto had a lower death rate in that category than the average compact or subcompact, Schwartz said after crunching the numbers. Nor was there anything about the Pinto’s rear-end design that made it particularly unsafe.

Not content to portray the Pinto as an incendiary device, ABC’s 20/20 decided to really heat things up in a 1978 broadcast containing “startling new developments.” ABC breathlessly reported that, not just Pintos, but fullsize Fords could blow up if hit from behind.

20/20 thereupon aired a video, shot by UCLA researchers, showing a Ford sedan getting rear-ended and bursting into flames. A couple of problems with that video:

One, it was shot 10 years earlier.

Two, the UCLA researchers had openly said in a published report that they intentionally rigged the vehicle with an explosive.

That’s because the test was to determine how a crash fire affected the car’s interior, not to show how easily Fords became fire balls. They said they had to use an accelerant because crash blazes on their own are so rare. They had tried to induce a vehicle fire in a crash without using an igniter, but failed.

ABC failed to mention any of that when correspondent Sylvia Chase reported on “Ford’s secret rear-end crash tests.”

We could forgive ABC for that botched reporting job. After all, it was 32 years ago. But a few weeks ago, ABC, in another one of its rigged auto exposes, showed video of a Toyota apparently accelerating on its own.

Turns out, the “runaway” vehicle had help from an associate professor. He built a gizmo with an on-off switch to provide acceleration on demand. Well, at least ABC didn’t show the Toyota slamming into a wall and bursting into flames.

In my blog, I also mentioned that Ford’s woes got worse in the 1970s with the supposed uncovering of an internal memo by a Ford attorney who allegedly calculated it would cost less to pay off wrongful-death suits than to redesign the Pinto.

It became known as the “Ford Pinto memo,” a smoking gun. But Schwartz looked into that, too. He reported the memo did not pertain to Pintos or any Ford products. Instead, it had to do with American vehicles in general.

It dealt with rollovers, not rear-end crashes. It did not address tort liability at all, let alone advocate it as a cheaper alternative to a redesign. It put a value to human life because federal regulators themselves did so.

The memo was meant for regulators’ eyes only. But it was off to the races after Mother Jones magazine got a hold of a copy and reported what wasn’t the case.

The exploding-Pinto myth lives on, largely because more Americans watch 20/20 than read the Rutgers Law Review. One wonders what people will recollect in 2040 about Toyota’s sudden accelerations, which more and more look like driver error and, in some cases, driver shams.

So I guess I owe the Pinto an apology. But it’s half-hearted, because my Pinto gave me much grief, even though, as the Ford manager notes, “it was a cheap car, built long ago and lots of things have changed, almost all for the better.”

Here goes: If I said anything that offended you, Pinto, I’m sorry. And thanks for not blowing up on me.

roller cam?

Started by waldo786, April 08, 2014, 09:31:34 PM

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amc49

X2. The words street/strip car and a four cylinder do not belong in the same sentence together unless there is a turbo involved. I view hopping up these as just an exercise in making the car powerful enough to hold its' own on the freeway with the big boys. Why the Contour and Focus zetecs were such a breath of fresh air, cars that could accelerate without dropping them off a cliff. That last 30 hp. is to kill for in street driveability..............

I ran an AMC car on the street with 5.0 gear and a 304 that would run in the elevens, it got pretty bad cruising for long distances and the gas price now would simply kill you.

Pinto5.0

Over the years I've had "STREET" cars with 4.56, 4.86 & 5.38 gears out back when I was street racing. I also ran slicks, soft compound street tires & rim screws on these cars. NONE of this stuff works the minute you jump on the highway & try to drive 65 mph for longer than 30 seconds. Trust me!!

Run the 3.40 & swap in the 4.56 for the track only. Rarely are you going to be using the engine below 2000 rpm so the slight loss of bottom end wont come into play.
'73 Sedan (I'll get to it)
'76 Wagon driver
'80 hatch(Restoring to be my son's 1st car)~Callisto
'71 half hatch (bucket list Pinto)~Ghost
'72 sedan 5.0/T5~Lemon Squeeze

jonz2pinto

Cam was to replace  2500-7500 power range cam(hyd roller)105mph,2 nd gear(auto)3.08 rear,205 50 15 tires.would not go any faster in drive.also 390 holley 4 on 4bbl offy inake,headers,unported heads(limiting factor i believe).ignition was hipo too. Slower then stock below 15-20mph.have 4.56 and 3.40 8inch stumps that i thought of using for takeoff but would not help top end.was going for street-strip car.
Pinto-is short for pint-o-fun.

65ShelbyClone

Quote from: Wittsend on May 01, 2014, 12:30:21 PM
These resonators seem like the water hammer pipes one installs in plumbing.

They look the similar, but don't operate in the same way.

Noise-canceling resonators operate on the principle of constructive and destructive interference. The drone in an exhaust is caused by constructive interference that makes sound waves stronger when they "stack" upon each other. Destructive interference does the exhaust opposite. Kind of like 1 + (-1) = 0.

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

Noise-cancelling headphones attempt to do the same thing electronically; they duplicate the noise audio 180° out of phase so it cancels the ambient noise.
'72 Runabout - 2.3T, T5, MegaSquirt-II, 8", 5-lugs, big brakes.
'68 Mustang - Built roller 302, Toploader, 9", etc.

Wittsend

Interesting. I have a '73 Valiant 318 that dumps two, 2" pipes into a single 3" pipe through a Flowmaster 50 and then out the back.  The drone is unbearable from 2,000-2,600 RPM.  These resonators seem like the water hammer pipes one installs in plumbing.  I didn't read far enough to grasp the science behind it (and I probably wouldn't understand it anyway). But, they all seem to be fixed length pipes.  I think I'd make mine adjustable (pipe sliding over pipe) since my experience has been that "math" and "real world experience" can often be two different things.

65ShelbyClone

Quote from: Srt on April 22, 2014, 03:21:46 AM
go with 2 1/4" pipe a muffler at the rear (walker makes a good one) and if you notice a harmonic vibration graft in a 2 1/4" perforated core straight thru (glasspack or similar)(make sure the core is 2 1/4" diameter too) in the straight section of the exhaust pipe ahead of the rear axle.

Another (usually cheaper and lighter) possibility is to identify the frequency of the harmonic resonance and build a suitable Helmholtz resonator to cancel it. I haven't tried it yet, but all the reports I have read are quite positive from Nissan Titan trucks to Fox3 Mustangs to late model Camaros. Some cars came stock with these noise-cancelling resonators. The Honda S2000 is an example.

It's really easy to identify the resonant frequency. All you need is a clean digital audio recording of it and free audio software like Audacity.
'72 Runabout - 2.3T, T5, MegaSquirt-II, 8", 5-lugs, big brakes.
'68 Mustang - Built roller 302, Toploader, 9", etc.

71HANTO

From SRT:


"charles what ID is the inlet?  been a while since i have laid any pipe or hung any mufflers but you may have to flip the inlet to one side or the other.  the bracket on the muffler (if you can) should be relocated to the rear, outlet end to take advantage of the stock hanger which IIRC is located to the rear of the stock muffler."[/size]


Steve, I just got the V-6 muffler delivered and the inlet (outlet) is only 1.75. It looked bigger in the E-Bay pictures. I was hoping for at least a 2 incher. I could try to mod it or I may need to send this muffler on. It is date coded 12/1978 without a speck of rust.


71HANTO
"Life is a series of close ones...'til the last one"...cfpjr

waldo786

I know what you mean Pinto5.0.  I work 10-12 hour days most days typically, and finding time to do things is not easy.  I'm willing to spend a little more for the opportunity cost, although I think it'd be cool to be able to go to the u-pick it.  Unfortunately there aren't many of those around here (DE), so it's usually just easier to buy them through other means.  I got a mid-90's ranger header from the same guy for $95 shipped.

Pinto5.0

I always weigh the cost of acquiring a part including labor into what I'm willing to spend to have one sent to me. Usually it's only 25% more to buy it off ebay versus digging it out of the boneyard myself. It's not penny pinching as much as work is running me into the ground Sunday afternoon through Friday morning so my spare time is limited. I have trouble finding time to mow my grass LOL
'73 Sedan (I'll get to it)
'76 Wagon driver
'80 hatch(Restoring to be my son's 1st car)~Callisto
'71 half hatch (bucket list Pinto)~Ghost
'72 sedan 5.0/T5~Lemon Squeeze

Srt

Quote from: 71HANTO on April 22, 2014, 08:58:15 PM
Just throwing is into the backpressure mix. I just bought a V6 muffler that I am going to use BACKWARDS to reduce the backpressure on a turbo'd 2.0L. I know some mufflers are directional but Pinto ones don't seem to be. This based on looking at (into) my original 71 muffler. It's hole'ier than the Pope and needs replacing. I think two tail pipes with add a little extra touch and sound better. To me, stereo usually sounds better than mono. Feedback good or bad welcome. I bought this muffler cheap so no big deal if I can't use it.

71HANTO


charles what ID is the inlet?  been a while since i have laid any pipe or hung any mufflers but you may have to flip the inlet to one side or the other.  the bracket on the muffler (if you can) should be relocated to the rear, outlet end to take advantage of the stock hanger which IIRC is located to the rear of the stock muffler.


i used to bend exhaust pipe for a living (many years) and a muffler like you have is something we hung a lot of back in the day.  gm cars with the small v6 used a muffler similar but with smaller inlet & outlet pipes. 


it should work just fine. 


just remember, 20+ lbs at the top of 1st and through all the rest of the gears will open your eyes wide.


i used to peg a 20# VDO boost gage with ease with the setup you have.  it WILL be fun!!! :o ;D



the only substitute for cubic inches is BOOST!!!

Wittsend

Again, I often forget my good fortunes. I haven't had to work (most) Fridays for the past 23 years. That said, the closest Pick A Part is nearly 45 miles away. And it is $10 in gas and $6 for yard admission (there are three self serve yards in the area). So, yes, I'm $16 spent even if I don't get anything. They also don't allow core exchange on 50% off sale days (which is the only time I go).  So, I often wind up eating my core charge because I'm not spending $10 in gas plus 2 hours of my time just to get my $10 core refund.  Sometimes I come home with a bunch of stuff. Other times nothing.

I'm also about 60-70 miles from the huge Pomona swapmeet.  But that is $20 gas, $10 parking, and $12 to get in.  So, I'm $42 in the hole before I buy anything. And, the last time I went, I really didn't get much.  So, while I'm a confirmed penny pincher I can understand the value that comes with paying more at times.

Ironically there is the "Largest Mopar Swap west of the Mississippi" (as they bill it) that is only $8 in gas, free parking and free admission.  I get more there simply because many parts are generic. An electric fan is an electric fan. It is were I got the fan for my Turbo Pinto (for instance).  In fact, I got a complete gasket kit for a Ford 289 at this Mopar show!

Pinto5.0

Quote from: Wittsend on April 21, 2014, 11:16:25 PM
Are you getting the cam/rollers new?  What is the going rate?  I saw a used set on Ebay for $99.  Wrecking yards would likely be cheaper.  We have Pick Your Parts around here with their 50% off sales.  I got the cam/rollers/lifters out the door for just under $30.  I guess I'm so tight with the dollar that it pains me even when it's another mans money. LOL

I got one off ebay with lifers, rockers & cam for $99 shipped. The closest pik-a-part to me is an hour each way meaning 2 hours time & $12+ in gas just to see if they even have one. In the end the $99 isn't that expensive considering.
'73 Sedan (I'll get to it)
'76 Wagon driver
'80 hatch(Restoring to be my son's 1st car)~Callisto
'71 half hatch (bucket list Pinto)~Ghost
'72 sedan 5.0/T5~Lemon Squeeze

waldo786

Wittsend, I actually was introduced to someone who sells the thru our forum.  I bought one with the followers for $172 shipped.  Not as cheap as yours but I also don't have all day to go out and pull one either.  I know what you mean about saving money.  I do everything I can to try and save.  I think I do pretty well overall.

71HANTO

Just throwing is into the backpressure mix. I just bought a V6 muffler that I am going to use BACKWARDS to reduce the backpressure on a turbo'd 2.0L. I know some mufflers are directional but Pinto ones don't seem to be. This based on looking at (into) my original 71 muffler. It's hole'ier than the Pope and needs replacing. I think two tail pipes with add a little extra touch and sound better. To me, stereo usually sounds better than mono. Feedback good or bad welcome. I bought this muffler cheap so no big deal if I can't use it.

71HANTO


"Life is a series of close ones...'til the last one"...cfpjr

Pinto5.0

Quote from: amc49 on April 20, 2014, 06:25:57 AM
Uh, back pressure has nothing to do with evacuation of cylinder, that requires NEGATIVE pressure to achieve.

That was actually quoting a couple different articles that state how backpressure decreases turbulence which keeps velocity up.
'73 Sedan (I'll get to it)
'76 Wagon driver
'80 hatch(Restoring to be my son's 1st car)~Callisto
'71 half hatch (bucket list Pinto)~Ghost
'72 sedan 5.0/T5~Lemon Squeeze

Srt

go with 2 1/4" pipe a muffler at the rear (walker makes a good one) and if you notice a harmonic vibration graft in a 2 1/4" perforated core straight thru (glasspack or similar)(make sure the core is 2 1/4" diameter too) in the straight section of the exhaust pipe ahead of the rear axle.


make sure you run the exhaust all the way to the rear of the car or you WILL have a lot of noise inside the car.



the only substitute for cubic inches is BOOST!!!

Wittsend

Are you getting the cam/rollers new?  What is the going rate?  I saw a used set on Ebay for $99.  Wrecking yards would likely be cheaper.  We have Pick Your Parts around here with their 50% off sales.  I got the cam/rollers/lifters out the door for just under $30.  I guess I'm so tight with the dollar that it pains me even when it's another mans money. LOL

waldo786

I am actually looking at doing an 86 ranger exhaust manifold as I'm hoping that's just a bolt in for the car and I imagine it flows better than stock.  I'm in the process of ordering a ranger roller cam, and we'll go from there.  I have the offenhauser intake and a holley 390 carb.

amc49

Depends on how many mufflers, fours commonly use two to really quieten things. Probably 2 or 2 1/4'', what I've used with good result. Using only one muffler may well be too loud there. Inline fours make more exhaust harmonic noise than other engines, the 180 firing order...........2 inch on single muffler, the bigger one with two.

Wittsend

Well, again I keep going back to the original premise of a Daily Driver with a relatively stock 2.3 (... a Ranger roller cam and header).  The owner needs to replace the exhaust and is contemplating what size exhaust and legal muffler to run (to the rear of the car)None of the wave tuning you mention applies because, as you note, the run is too long and it becomes irrelevant.

I'm truly not trying to be obnoxious, but given the exhaust described above (see underlined) what would you recommend tubing size wise?  And why?  -   I mean some tubing size needs to be selected before the work can begin.  And regardless that none of the science of the wave tuning is applicable there still should be some form of reasoning (no matter how minor) in the size selection.



amc49

LOL....................

I agree with the top half of that but not a lot of the bottom half. This whole pipe velocity misses the major point like so many of the discussions do. The point is this. You want velocity until you get to the end of the tuned pipe length and NO MORE, anything beyond that is later pipe inhibiting the earlier pipes' performance. If you can trick the engine into thinking the exhaust has hit atmospheric pressure then the exhaust tuning works like gangbusters, indeed the engine thinks any header there is open. The atmosphere has no velocity to it at all. so what happened there? And the maximum power producing condition.

No one qualifies the pipe velocity statements with that phenomenon at all. They just continue to assume it must mean the ENTIRE pipe must be high velocity and simply not so. The major reason why? Once you have passed the tuned length all else there is fluff, there will be no real effect. You CANNOT get tuned length open pipe performance with full length pipes, anyone trying has pretty much failed there. When you look for velocity in tailpipes you have restricted the pipe further up to kill power, end of discussion. Why? Because if sized to make velocity they will stop the exhaust plug from firing through the pipe earlier and further back as fast as it can. It wants atmosphere (zero resistance) there, no amount of velocity later on can replace that full open condition. The later pipes' area to be plowed through will inhibit the exhaust pulse as the gases stack up in the pipe to be shoved further back, sizing for velocity only makes that worse. Velocity later on in the system will not aid one other big tune of simulating open pipe, the pressure backflow that results in a positive pulse reversing to go back up the pipe and acting as a pipe stuffer to limit the loss of mixture at the end of overlap, full length pipe pretty much totally destroys that, it does not happen. Velocity does nothing for that at all either, in fact it squelches the effect. But short pipes like straight through header mufflers will let some of that happen.

You wave tune with short pipes, once you must use full car length pipes you must give up true wave tuning, all you can achieve is flow enough to simply let engine breathe easier, there will be a big loss in power with the wave tuning effect gone. Pretty much impossible to get around it, but a trick or two can help it get better.

Enter the difference between true sound wave tuning and vacuum tuning ala multi-tube headers. Two totally different animals.

Lemme guess, I went and made it worse again right?

Wittsend

Uh, back pressure has nothing to do with evacuation of cylinder, that requires NEGATIVE pressure to achieve."

Which..., (unfortunately)..., brings us back to velocity.  Ok, I'm no scientist, or expert, or anything, but the theory goes as such (for the benefit of those who don't know - or  those who hear that "backpressure" is necessary):

On the exhaust stroke the piston is slowing (and in fact, for a fraction of a second, stopping) as it approaches TDC. The "push" of the piston becomes less effective in removing exhaust gasses.  However, as the exhaust gas is moving down the manifold (header), tailpipe etc. the momentum helps to void (draw out) the burned gasses from the cylinder. The best way to have that "drawn out" momentum process is to have the exhaust moving as fast as possible (velocity).

So, this is where pipe size becomes tricky.  Too big a pipe and the momentum drops off fast.  Too small of a pipe and the momentum is hindered (in relation to its volume) to moving its fastest.  Ideally the pipe diameter would keep expanding and contracting as needed.  That way you could get maximum velocity dependent upon the volume of the gasses.  The expanding pipe isn't going to happen so any pipe size is a "one size" compromise.

Say, someone goes into the muffler shop and asks for a 3" exhaust. They state, "you won't have enough back pressure."  What they really mean is that you won't have the best velocity of exhaust gasses for a street driven car.  Now to be fair, compared to a 3" pipe, a 2-1/4" pipe may actually increase backpressure as an end result of having higher velocity.  But, increasing backpressure is not the goal, increasing velocity is.  The tricky part is to have the benefits of increased velocity without the detriments of increased back pressure.

Now, that is likely "Basic 101" on the subject. There is the factor regarding the open and closing of the valves that generate pulses. There is the factor of overlap (where both the intake and exhaust valves are open at the same time). And that is probably only "102" on the subject.  Apparently there is an 825 page book on the subject.  And, after all that theory there is "real world" experience. Certainly for me WAY beyond my comprehension and thus my ability to apply. But, when much is on the line applying the upper end of this subject is applicable.

Anyway, my goal is just to point out at the bottom end that backpressure is not the goal. And, that (in a street driven car operating at various RPM's and loads) ideal velocity is fleeting. AND, that this basic understanding is just cracking the ice on the subject.

Now, do you all love me or hate me???


amc49

Uh, back pressure has nothing to do with evacuation of cylinder, that requires NEGATIVE pressure to achieve.

dick1172762

Its better to be a has-been, than a never was.

Srt

interesting thread.  one thing that is obvious is the enormity of opinions on what works.


here's mine: if it feels good, go with it.


if it sounds good, go with it.


what else can you ask for?
the only substitute for cubic inches is BOOST!!!

amc49

Most race engines do well to exceed 85-90%. Why VE is always at a lower rpm.

Necessary back pressure as understood by most is a myth, I can show it several ways, but open headers pretty much lays that to rest. The idea developed from minds that did not understand how exhaust works. Look at when the idea began, in the early part of the century, we've learned much since then.

What works on race cars works to a lesser degree on street ones as well.

'They will likely randomly select a pipe size between 2" and 2-1/2" with little reason behind the decision.'

Yes they will, but not me. Not nearly the first time I don't follow the crowd either.

FYI, these engines are too small. To get anything more than maybe 25 easy bolt on hp you WILL be going toward the race end of the spectrum, there is no way to pick up more power without shelling power band as a consequence unless you turbo. Four cylinders get b-tchier and more quickly than  bigger engines do and smaller size only aggravates that more. Why same cam timing in a bigger motor will idle smooth but lopes in smaller engine.

I digress as usual so I will shut up, thanks all that listened to the rave.

Pinto5.0

I was always taught that in a non-turbo engine operating at a moderate & steady RPM that a certain amount of backpressure was desired to reduce turbulence & keep velocity up in order to fully evacuate the cylinder of spent hot gasses. The cooler empty cylinder then draws the fresh intake charge better than one contaminated by leftover combustion.

A Pinto engine is probably 85-90% efficient on it's best day where race engines exceed 100% VE so they benefit from an open exhaust with little restriction.

Turbo engines pressurize the intake charge & operate well above 100% VE so the free flowing exhaust with no restriction is preferred.
'73 Sedan (I'll get to it)
'76 Wagon driver
'80 hatch(Restoring to be my son's 1st car)~Callisto
'71 half hatch (bucket list Pinto)~Ghost
'72 sedan 5.0/T5~Lemon Squeeze

dick1172762

I tried to shut this down on reply # 28. Maybe now????
Its better to be a has-been, than a never was.

Wittsend

AMC 49, I think we are getting to the point of comparing apples to oranges.  The poster was discussing 2,500-3,000 RPM range as a daily driver.  You are discussing race (or near race) cars at wide open throttle.  In the end 98% of guys will just go to the muffler shop (or do the work themselves).  They will likely randomly select a pipe size between 2" and 2-1/2" with little reason behind the decision.

So, I'd still take the "velocity" perspective over say..., the supposed need for "back pressure" any day (not that anyone mentioned that argument).  At least for me that is about as complicated as I can mentally get.  The likelihood one would benefit a daily drive based on race experience (or reading a 825 page book) is probably far less that what they "believe" they have benefited going to any larger exhaust.  Don't get me wrong, I can appreciate experience and knowledge. I just think it needs to be applicable to the value of the task at hand.  After all we are talking about near stock Pinto's going down the road between 25 MPH to 65 MPH.

amc49

Got the book BTDT................that guy is plenty smart.