CVF-

It took you 6 posts to say the same thing that I and several others have been saying all along.

Is it illegal for someone to tamper with or disconnect their emissions control devices? Yes

Will you get caught? Probably not

Will you get a significant performance boost out of disconnecting your emissions control devices on a 351M/400? Again...probably not

You've made you point and you need to take a hint from the previous locked threads.


__________________


Bill,

Just documenting what I believe to be the truth.

Regarding your previous post:

I disagree, you are mistaken to believe, that disconnecting the EGR won't make a difference in a vehicles' performance. Let me explain why-

I have extensive experience doing this- before/after testing. Let me state first hand, it makes a VERY NOTICEABLE improvement by disconnecting the EGR on every vehicle, even on my '91 and '95 cars. Especially at part throttle, as the engine will run a bit richer, and have more power. The added tailpipe emissions will be minimal, with the converter still in place (which is how I run the cars. My truck had no converter when purchased, and EGR already disconnected, and I'm not about to put that stuff back on !!)

No reason to lock the threads. Taking a hint from my previous posts, you may realize I know what I'm talking about, and I have the strength of my convictions. In other words, I'm sticking to my guns, sir ! I have a few shingles hanging on the wall to boot, and I didn't get them by caving in to intimidation.

If I were to ask for a "roll call" of all forum members, who have their EGR's disconnected, the list would be a mile long. Edelbrock sells many more non-egr intakes, and almost no egr equipped intakes, for the 335 series engines. The other sites I have quoted in the previous thread also attest to the fact, THAT EVERYONE IS DOING THIS. Virtually NO ONE builds a 351M/400 using an EGR valve, and the CLeveland engine up to 1972 never even had an EGR valve. Why try to hide it ??

Thanks for listening.

CVF

 

You may notice I said significant performance increases from disconnecting the emissions equipment. Sure you may gain a couple of horsies here or there, probably about the same as you'd get from a good tuneup. The fact is that the 351M/400 engines were calibrated and carbed to run with EGR so disabling or removing it simply isn't going to net you a whole bunch of power.

I'll be more than happy to change my opinion if you can provide some evidence to verify yours. Feel free to post any "before and after" dyno results which back up your statements.

 

The purpose of an EGR system is to allow the engine to run a leaner air/fuel mixture than is optimum. It does this by introducing inert burned gases into the cylinder at part throttle, thereby cooling and slowing the combustion event. When the EGR is disabled, there is no change in the air/fuel mixture (on a carbed engine). This is because the previously introduced exhaust gases are simply replaced by more fuel/air, at the same ratio as before. The engine is not running richer, it's actually running at the same (lean) ratio as before. This is why larger carb jets are usually necessary when the EGR is disconnected. The extra fuel cools the (non-EGRed) combustion charge and prevents the detonation that usually occurs.

Disabling the EGR dosen't give any extra power, since the EGR is already inactivated at full throttle, UNLESS bigger jets are installed to bring the stoch ratio back to normal. If bigger jets ARE installed, then the mpg will also go down.

In conclusion, disabling the EGR does little except lower the mpg and increase emmissions. Hope this clears up some misconceptions concerning EGR systems.
Cheers
Don

 

I disagree. Disconnect your EGR and take a drive, you'll feel a much better mid-range part throttle response, much smoother, as forum members here have reported also.

Bill, show my ONE NASCAR, NHRA, INDY, monster truck, or puller that runs an EGR valve. Good luck with that one. It's an emission device, not a performance device. There's a difference.

I also disagree on the lean/rich statement. Spent exhaust gases routed to the intake manifold with an EGR, are basically a metered vacuum leak. Instead of sucking atmospheric air though, the "leak" is sucking exhaust gas. ANYTHING other than fuel that enters the intake stream, reduces the amount of fuel present, and leans the mixture. It "cools" it because you are basically throwing burned ashes on the fire, and putting it out. You are assuming the spent exhaust gases are the same as unburned fuel, NADA, the exhaust does not burn again, it is INERT. The fuel it's replaced with when you disable EGR, DOES BURN. Again, there's a difference. Capish ??

You fellas have to remember, that most if not all 351M/400 engines were pre-computer emission controls of the 1970's, which were notorious power-robbers. This forum is dedicated to those engines, not new engines. These controls turned a 400" engine into a slug, which is why the 351M/400 engines had such a lousy performance image until now ! It took hot rodders, taking the emissions off, and treating the engine to REAL hot rod parts, to wake it up. You won't see any sensible 351M/400 engine builder putting an EGR or cat converter on his truck. C'mon fellas, time for a reality check- it just doesn't happen. Look at my other thread with links and quotes- everyone disables the EGR on the 335 series motors. It has become a basic step in the build process, and it's old news by about 20 years now.

And why do you think those non-EGR Edelbrock 351M/400 intakes on ebay, are routinely bringing $100 each now ?? I have yet to see an EGR equipped E-intake even sell...

 

Sorry...no dyno...no dice. You can't compare racing engines to street engines. It's comparing apples to oranges.

Your explanation of the EGR makes no sense whatsoever. Just because you replace exhaust gas with A/F mixture doesn't make the burn any richer because the A/F ratio doesn't change. If it was lean with EGR then it will still be lean without EGR, carbs can't adjust just because you disable the EGR unless you change the jets.

The emissions systems weren't what took the power away from the engines, it was the retarded timing and lower compression ratio.

 

Bill,

You are forgetting, EGR valves even when hooked up, are not working at idle or wide open throttle, by design.

You don't have a leg to stand on, saying an EGR doesn't reduce power. It sure as heck doesn't make more power. What you should be saying is, you have no experience in the matter either way, you never tried it.

Just try disconnecting the EGR on a 4-cylinder. It feels like someone put 2 more cylinders under the hood.

Your rich/lean mixture argument doesn't hold water. This is why: Are you saying if I pull a vacuum hose off, that doesn't make it leaner ?? It sure does make it leaner, think about it. An EGR valve is doing the same thing. Here's proof: OPEN THE EGR VALVE BY HAND WITH THE ENGINE RUNNING, THE ENGINE WILL STALL. It a basic mechanical test that all mechanics used to do, to check EGR passages for blockage and EGR operation.

Why do you think the EGR is shut off at idle, even if it's still hooked up ?? Why do you think the EGR is shut off at wide open throttle, even if the EGR is hooked up ?? Because, to open it at those times, would either stall or destroy the engine, due to a LEAN CONDITION.

Your "no power loss" theory also leaves out the fact, the disruption of exhaust flow in the exhaust valve pockets where the EGR passages are. Instead of going out the exhaust manifold or header uniformly, the exhaust in those areas pulsates back and forth under the intake manifold. Now, what are headers for again ?? Do they make more power in your opinion ?? If they do, then exhaust under the intake is a no-no, cuz it's working against your headers, effectively changing the flow charactertics of those affected cylinders.

A racing engine is only a more efficient passenger car engine. It's apples to apples, a valid comparison.

I wouldn't be caught DEAD asking a dyno operator/owner to put an EGR on a engine to test before/after. They all already know, EGR's are a big power robber. They'd laugh me out of the shop for even asking. That's like asking if a 4-barrel 650 cfm makes more power than a smaller 2-barrel 300 cfm. Why re-invent the wheel ?? A dyno operator is not that low on the learning curve.

 

CVF-

How bad does your engine spark knock, under load, on 87 octane, w/o changing factory ignition timing settings? Because of the lack of quench with the M engines, EGR helps to prevent detonation, under load. try pulling a grade with an 8000 lb trailer behind you, and you'd swear the pistons were swapping cylinders.

 

hey I not a fan of CVF's attude( no offence ment) but he is right about the point of leaning out the mix. For example let made a batch of "kool-aid" then go and add some old dishwater is it now something you are going to drink? so why do you want to add exaust gas to the A/F after the carb has mixed up what your engine needs?
just another way to look at things.
Jason
BTW I have a tired 400 that loves to DRAG(with a chain) 1500+lb oak logs through the mud. The only thing that stop it is tration when too much mud piles in front of the log, and then I just roll the log then keep pulling to where I am going.

 

I never said that the EGR system doesn't reduce power. My point is that simply disabling the EGR system in a vehicle which is designed and calibrated to use EGR will not give you a significant boost in power because fuel delivery system especially in an older engine can't compensate for it.

All you'd have to do to prove your point is take you vehicle to a chassis dyno and do 2 runs, one with the EGR hooked up and another with it disabled. Without that it's all smoke & mirrors.

Racing engines are designed with 1 thing in mind, maximum power output per CID. Period. No thoughts of emissions are even entertained so trying to compare that design process to a daily driven passenger car or truck engine is simply not a valid comparison.

 

cvF, I agree with your general assessment of the EGR as a power robber, but you are not correct about its effect on the fuel/air mixture.

If you leak vacuum below the throttle plates by pulling a hose off, you allow additional air (i.e., O2) into the fuel/air mixture, thereby leaning the mixture (more O2, same amount of fuel).

An EGR valve does not do the same thing; it does not introduce additional O2 into the mixture.

The EGR system introduces exhaust gas, which is chemically inert in the combustion reaction. Your observation on that fact is correct, however, the exhaust gas does not change the fuel/air mixture (ratio of fuel to O2) because it is neither fuel nor O2.

That is not true. After the initial mixture (ratio) is determined in the carb, the ratio of fuel to O2 can only be altered by introducing either more fuel or more O2.

Since the fuel/air mixture is determined by the carb's metering, upstream of the EGR valve, the exhaust gas displaces both fuel and air in the intake charge, reducing the quantity (volume) of both reactants, but not changing the ratio.

Reducing the volume of the intake charge effectively reduces the engine's volumetric efficiency and displacement, which is, ironically, an effect similar to NASCAR restrictor plates.

What happens when you lean the mixture a little bit at idle? The engine speeds up. That is the exact principle behind the hot-idle compensation valves used on later model Motorcraft 2150 carbs.

BTW: If your engine slows down when you lean the mixture a little bit (not a lot) at idle, then your idle mixture is adjusted too lean and you've got borderline lean misfire.

When the EGR valve is opened at idle, the engine slows down. That is the opposite of what happens when you lean the mixture at idle.

It's more like blasting the fire with a CO2 extinguisher, but you are correct on that point. That is why opening the EGR valve at idle slows down the engine, eventually stalling it if you open the valve far enough.

You can see the difference between a vacuum leak (overlean mixture) and an open EGR valve on a simple 3-gas analyzer.

By design, EGR is shut off at WOT because of its inherent power-robbing effect (reducing the volume of the intake charge). Engineers who designed EGR assumed that when the driver opens the throttle all the way, he or she demands maximum power from the engine, possibly in response to an urgent situation. Carburetors have enrichment devices (power valves, throttle-controlled metering rods, etc.) that provide richer than normal metering at WOT, and which mitigate the specific emissions EGR is intended to reduce. In "normal" street vehicle use, very little time is spent operating at WOT, which limits the potential benefit of emissions control under that condition, particularly in light of its probably urgent requirement for maximum engine power.

 

Wow.

Now I'm really confused................

Do I believe what I just read, or do I just spend my own hard earned time and money to go out and figure it out for myself???????

I think I'll choose option # 2. At least that way I get more practice and I will have the numbers to dispute or correlate the above arguments.

Merry X-Mas.

 

Thanks Bubba

 

If you open the EGR Valve at idle, it won't "slow the engine down" bubba, it will STALL THE ENGINE. Try it and see. I'd say that pretty much proves, that EGR valves are DETRIMENTAL to performance.

EGR gases are PRET-TY FAR from a "cold blast of CO2" as you incorrectly state, they are actually around 2500 degree F. Ever touch a hot exhaust manifold ?? It's not "cold" That's what is coming in and hitting the air/fuel stream. Follow the passages in the heads and intakes when apart next time, and see for yourself.

And it's not ONLY CO2 either, its partially burned HYDROCARBONS (HC), OXIDES OF NITROGEN (NOX), and CARBON MONOXIDE (CO), along with CO2 and H20 (water vapor). Those are the major components of exhaust gas, and THAT'S what your re-introducing into the INTAKE MANIFOLD, when you open the EGR valve. That's why it STALLS THE ENGINE at idle, and makes it LOSE POWER.

Why are EGR valves SHUT OFF at wide open throttle then ?? Think about it. They LEAN THE MIXTURE. Whether or not it is O2, or exhaust, or CO2, or whatever, it's still leaning it out. Here's why.

You have a cylinder filled with A/F mixture of 14:1- ok, good.

Now, you have a cylinder with an EGR valve working on it, and you fill 1/4 of same cylinder with exhaust gas, the rest with air/fuel from the carb.

It sure as heck "AIN'T" 14:1 air/fuel anymore, is it. It's less, and you're basically putting the fire out, not "cooling" it with CO2.

Think of it as a full glass of beer without EGR, and a 3/4 full glass of beer with EGR working. We like beer, like engines like fuel. Now, put a head on it !!

 

quote:
[Do I believe what I just read, or do I just spend my own hard earned time and money to go out and figure it out for myself???????

I think I'll choose option # 2. At least that way I get more practice and I will have the numbers to dispute or correlate the above arguments.



To "figure it out yourself", you'll have to DISCONNECT IT and TEST DRIVE IT. In effect, you'll be BELIEVING WHAT YOU JUST READ, cuz you have been persuaded to try it.

Been there, done that, and I'm here to say, disconnecting the EGR will GREATLY improve your part throttle driveability. I'm running 3 vehicles with it off- and have been doing so for over 20 years now.

Remember, I spent months in the classroom and shop, learning just exactly what an EGR is, and how it works. Taught by a factory rep. Once we found out exactly what they did, everyone started blocking the EGR's off with plates on their own cars.

What happens with EGR hooked up is, you have to push the gas pedal down further, to get the same acceleration. That's cuz you're also getting exhaust gas inside the intake, instead of just fuel, with it hooked up. Mechanical nonsense.

Engines run on fuel, not exhaust gas. Right ?? Once it's burned, it can't burn again.

 

PS- Bubba, you have to remember, that exhaust gas from EGR is mixing with that fuel and air, it's throwing the entire mixture off. In effect, you end up with LESS FUEL AND AIR, cuz some space has been taken up by "inert" exhaust gas. There IS oxygen in exhaust gas, in the form of CO, CO2, and H20 (water vapor). So how can the a/f stay the same ?? Think about it again...

If you want to introduce something into the intake manifold to "freeze" it, introduce NITROUS OXIDE. Now, that IS very cold and will send the power through the roof- but you have to richen up to burn it.

The EGR is the opposite of Nitrous. It takes up space that could be held by air/fuel, and heats the intake charge, and leans it out to boot. No kidding it burns cooler in the end, that's cuz THERE'S LESS FUEL TO BURN.

Pulling a hose off the carb may send the idle up, but pull a big enough hose like the PCV and power brakes, and it STALLS THE ENGINE. Turn the idle mix screws all the way in, it will eventually make the engine idle rough, then stall it. Just like opening the EGR at idle will do...try it.

finally, BUBBA, IS YOUR EGR HOOKED UP ??