2nd Gen 5.0L Performance Mod List

[Centaurus5.0]

 

[Centaurus5.0]

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[damarble]

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[CDW6212R]

The actual power numbers are the only thing needing debate. We can and you already did identify the main issues to improving performance. I'd add braking to the list, people often forget to be sure the brakes are in top condition with their hot rods.

Better fluids is often the best and easiest first step to take for improvements. Synthetic fluids will help any vehicle, from stock to race only. The transmission can appreciate some love to, with great fluid, and a deeper pan, external filter, bigger cooler if needed etc.

I'm going to begin with my exhaust when I get that far, maybe February now. I'll find the truth to what a big exhaust will do for a bone stock 302 Explorer. I've said before too, don't talk any hp numbers unless the computer has been re-tuned. It isn't fair(accurate) to claim a power loss from a big exhaust, when the PCM is left stock, which everyone does(which is still wrong). I will give my truck a tune up before a dyno test, making a baseline. Then I'll remove everything from the collectors back, and rebuild it from the back forward. When I get the exhaust on it, then I'll have it re-tuned(not tested). After tuning, then it's time to test it again. I don't expect huge numbers, due to the stock horrendous manifolds. But maybe I'll gain 15+rwhp, we'll see.

Note that I have a VC2000 test device, which is an accurate G-force 1/4 mile tester. I'll be able to use that for relative gains, but best of all, it produces times and G-force data for many steps(30 foot, 60 foot, 330 foot, more, and 1/8, 1/4). I will know that the power is better at all rpm's, all speeds, from detailed tests.

The manifolds will be hell to make I'm sure, because I am no welder. But I'll figure out how to get it tacked together at the least. I've seen a few vehicles examples(Mustangs etc) with 302-306's and mild combinations, with 1.75" headers, one long and others shorties. I think 1 3/4" is the way to go for performance. Do a 1 5/8" if you stay really stock to mild. I'll start them as 1.75", and merge them with each other from front to back ports, into at least a 2.5" collector, 3" if I can find space for the flange(V-band clamp/flanges).

 

[Centaurus5.0]

I cant wait to see your results Don!

I'm going to try and leave out my own conjectures on what makes what hp at what rpm in the main post as we both know how heated it can get. But If there is a back-to-back dyno showing a gain, tuned or not, I think it's fare to post a ball park hp figure. I'm trying to list parts as general but factual as possible for a broad audience though. I did state some numbers for the exhaust because there was a dyno sheet to prove it. Your right, a tune is optimal after any mod to see the full benefits, but we have to work with what evidence is available from others to determine what makes the biggest improvement. Your findings will be valuable at getting to the bottom of the exhaust question, no doubt. Like TMH's test rig, did it get a dyno tune along with the header install? Maybe they free'd up 55lbs of torque instead of 40lbs after a tune I believe is what your saying. But one number doesen't tell the whole story either way, it's the curve and average power though out the usable rpm range thats important. But since I can't explain a numbered curve with words to well I use ballpark figures and averages and terms like low end high end and 'ish a lot.

 

[Centaurus5.0]

@CDW6212R

When determining hp gains I roughly equate the Explorers 5.0l to the old E7 HO engine. Even though the explorer has the bigger gt40 heads and intake, the truck camshaft is severely limiting their potential. The opposite is true with the 87-95 5.0L E7 motors were the intake and heads are limitng the power and not the cam.

Factory Ratings:

94-95 Mustang GT 5.0L
215HP@4200RPM
285HP@3400RPM

98-01 Explorer 5.0L
215HP@4200RPM
285HP@3300RPM

Almost the exact ratings from the factory? Now I still can't find if these tests are done with the vehicles full exhaust system or a set of "dyno" headers with accessories installed or what.

Here they performed a full spectrum of bolt on tests on Steeda's dyno:
5.0 boltons dyno results - DFWstangs Forums

It showed that installing 1 5/8th Motorsport headers on a stock 5.0 netted zero hp over the factory crimped 1 1/2" manifolds. I find it safe to assume that as long as you have the stock explorer cam the same would hold true for the explorer motor BUT if we had a 1 5/8" headers available for our rigs I wouldn't say they'd loose any hp either. Then again, the exhaust ports are bigger on the gt40 vs e7 so they may make more just by the fact they match better (by not protruding in the exhaust path) and not necessarily the need for the extra flow provided by the larger primaries.

It also showed the muffler swap gaining 5hp which backs up Vizard's claim that muffler design is more important than the exiting tailpipe diameter. You also have to figure as the hot exhaust pulse travels down the pipe, it looses heat and thus energy and thus velocity. Putting a smaller diameter pipe on the end of the system can actually help improve torque by keeping the velocity up.

Any header designer can tell you (and often do on their website) that too large a pipe diameter will hurt torque and it's better to err on the smaller side. Putting 1 3/4" headers on a mild 306 isn't going to make more hp than 1 5/8th. You don't need dyno to tell you that.

 

[Centaurus5.0]

I'd add braking to the list, people often forget to be sure the brakes are in top condition with their hot rods.

Good idea! If you want to write a segment, I'll paste it into the first post and give you props. You know WAY more than I do about brakes wheels and tires.

 

[CDW6212R]

@CDW6212R...
You also have to figure as the hot exhaust pulse travels down the pipe, it looses heat and thus energy and thus velocity. Putting a smaller diameter pipe on the end of the system can actually help improve torque by keeping the velocity up.

Any header designer can tell you (and often do on their website) that too large a pipe diameter will hurt torque and it's better to err on the smaller side. Putting 1 3/4" headers on a mild 306 isn't going to make more hp than 1 5/8th. You don't need dyno to tell you that.

This is one of the biggest myths I want to prove wrong. Everyone seems to agree that high velocity throughout the exhaust is desired, and I've disagreed for about 20 years.

Headers are different, and that's the key point I get and most people don't. That's where the confusion begins.

Only in the headers does smaller pipe size matter for positive affects, going too big will hurt low end power. The header is the only part of an exhaust system which can increase(or decrease) power between different pipe sizes and lengths. That affect is called scavenging, and it occurs because of the merge locations shape and size, how the pipes come together, typically the collector. Tri-Y headers merge the pipes in pairs, 4 to 2, to 1 at the back, so those have three merge locations.

The scavenging is the only power gain possible in an exhaust, and that's what people do not understand. There is a pull on adjacent pipes which helps flow from that other branch. Once the exhaust flow has passed the collectors(actual point is where a drag car cuts off the collector(run it down the track with extra long collector pipes, and cut it off where paint burns off)), then it's all just a restriction to the moving gasses from the collector. That is why drag cars have no exhaust, there's nothing to gain past that.

That magic point is where a crossover could help, but since that's too far forward(impossible to place one there), any crossover after that simply reduces back pressure(restriction). A crossover does not scavenge, it only reduces back pressure there.

That restriction reduction means less power is lost trying to force gasses out. That is the key to gaining power from an exhaust, simply eliminating restrictions to flow. That concept is identical to what people commonly know about parasitic power losses inside an engine. As you reduce frictional and mass losses inside an engine, power output goes up. That's what piston coatings do, and reducing crank reciprocating masses, and a windage scraper etc. It all makes no more power, but more is produced because less is being wasted fighting the frictional and mass forces.

So my goal is to enlarge the exhaust behind the collectors, to result in as little restriction as possible. That's difficult for these Explorers, but I'll still make it as big as I can. Typical powerful Mustangs never have a 2.25" exhaust(stock is 2.25" dual, Explorers are 2.25" single(count the mufflers and tail pipes)). They all have at least 2.5" dual systems(much larger than a single 3" pipe), so I believe a minimum should be 2.5" dual mufflers and tail pipes.

 

[Centaurus5.0]

That is why drag cars have no exhaust, there's nothing to gain past that.

They also don't worry about a broad torque curve for daily driving and operate in relatively small (very top end) rpm window. Camshaft specs also have an input on making a certain exhaust design work or not (and vise-versa). Another point but perhaps minor one is at some point the weight of a full system would override any gains. 50+ pounds is a lot in racing. They also to worry about choking out there family with exhaust gases.

That magic point is where a crossover could help, but since that's too far forward(impossible to place one there), any crossover after that simply reduces back pressure(restriction). A crossover does not scavenge, it only reduces back pressure there

This maybe be were the biggest gains (free up the most) might come from if your trying to improve the exhaust for more power for a hotter engine out an oem style exhaust. Testing can tell.

That restriction reduction means less power is lost trying to force gasses out. That is the key to gaining power from an exhaust, simply eliminating restrictions to flow. That concept is identical to what people commonly know about parasitic power losses inside an engine.

But restriction is whats also creating scavenging?? If heat energy is being lost as it travels down the pipe, wouldn't that mean a less diameter at the end won't hurt? If you were to put your hand (with a heat resistant glove of coarse) over one of the header collectors of a running engine, the pressure is much stronger than over the tailpipe where both banks are running to. This energy loss comes from heat dissipation. And would this not change depending on the outside temperature and length of the system? So if there is less energy at the tailpipe then there is at the collect, one can assume it doesn't require the need for the same diameter pipe and therefore wouldn't be restrictive.

So my goal is to enlarge the exhaust behind the collectors, to result in as little restriction as possible. That's difficult for these Explorers, but I'll still make it as big as I can. Typical powerful Mustangs never have a 2.25" exhaust(stock is 2.25" dual, Explorers are 2.25" single(count the mufflers and tail pipes)). They all have at least 2.5" dual systems(much larger than a single 3" pipe), so I believe a minimum should be 2.5" dual mufflers and tail pipes.

Actually, we have a dual 2.25" exhaust system up to the muffler. We also have a longer exhaust system. Well also have a larger muffler. We aslo don't have the marketing concern to have a Mustang sound like a Mustang. We also don't have a cam thats making power to 4800-5800rpm where the added flow would be needed. If we both agree with Vizard, the engine see's the muffler (based on design) as the end point of the exhaust system. The tailpipe is there just to exit the noxious gases away from the occupants. So if you installed a 2.5" 2-in-1 muffler, wouldn't the tail pipe (or two) be irrelevant? and if it's not, wouldn't it effect the velocity of the exhaust energy? Conundrum?? I did recommend putting on a larger exhaust if your increasing the power when revving higher, more cubes or forced induction.

Stock engine is rated for 215hp. If you believe its really just a hosed up 93' Cobra motor (I don't, cams are different, look at the factory rated rpm torque), then say 235-260hp.

Using Vizard own calculations for a "zero loss" system (does zero loss mean zero backpressure?)

Per square inch of exhaust tubing there is 115 CFM of flow.((3.14 * radius^2)*115[*2 for a dual exhaust system])/2.2 = Max hp supported with zero loss

2.5" single is good for you tell me
2.75” single is good for 310hp
3” single is good for 370hp
3.5” single is good for 503hp
4” single is good for 657hp
2.25” dual is good for 457hp
2.5” dual is good for 513hp
3” dual is good for 812hp

We don't have a single 2.25" exhaust. We have a dual 2.25" (with no cross over) up to the muffler. What is is in debate is how much of an effect the muffler and tailpipe has on the overall system.

I can't find section525's post with the dyno with no exhaust but I remember it wasn't more than 20hp, again with the e cam. So if your reasoning is correct, you won't make more than that spending a couple thousand dollars going full retard making a 1 3/4" header & dual 3" exhaust for a stock 5.0 in a 4500lbs explorer.

In the case of 99% of the people that's going to read this post looking to improve performance on their rig, A performance muffler and a single 2.5" tail pipe is adequate and easiest for a stock or even mildly modified (some port work, 5200rpm cam) engine. If your looking for a more killer exhaust note or magic hp, everyone is welcome do as they please.

**edited for spelling**

 

[CDW6212R]

...

But restriction is whats also creating scavenging??...


Actually, we have a dual 2.25" exhaust system up to the muffler. ..

2.5" single is good for you tell me
...

We don't have a single 2.25" exhaust. We have a dual 2.25" (with no cross over) up to the muffler. What is is in debate is how much of an effect the muffler and tailpipe has on the overall system...

....

Why I can't argue with that is a difference in logic, I don't comprehend those illogical thoughts. Scavenging is the relative vacuum created in adjacent branches where two or more air flows come together, pass by each other. Each branch or pulse creates a minor but measurable pull on the other branches. A restriction is a higher pressure at some point, created by something downstream that reduces mass flow. Any tight opening or area creates a restriction.

Every object slows down airflow, the cats, mufflers, resonator, connections(ball sockets), the weld points, and the pipe itself, are all restrictions. Restrictions all slow down the airflow exiting the engine, they are making it harder for the gasses to get out. That's back pressure, and it's all bad, all of it. The velocity of flow at some point along the system is not a measure of power.

Power comes from airflow of/inside/through the engine. The engine converts fuel and air into rotation of the crankshaft. Anything that increases the airflow speed through the engine, increases power. So back pressure in the exhaust system reduces power. You want to know how good your exhaust is, stick a pressure gauge in it somewhere. Check it at the front of the muffler, you'll see more clearly then.

A straight piece of 3" pipe has less restriction than a 2.25" piece of straight pipe. An engine only produces a certain amount of power, it's a closed system, which includes the inlet and exhaust parts(all of them). The front accessories are parasitic losses, as is the transmission, TC, axles etc. That's obvious stuff to car guys, and an engine dyno measures power without those restrictions, and without the exhaust restrictions, but with headers on.

Everything past the headers reduces final output power. If you put a full exhaust system onto the headers of an engine on a dyno, and tested it, removing one component at a time from back to front, the results would change for each item. Why is that, if the tail pipe is irrelevant, or the single muffler makes no difference than twin mufflers etc?

That is my point, every component does matter. The reason each matters is the why of it, each one increases the difficulty of the exhaust getting out. Without any exhaust, maximum power results because the gases are free instantly, nothing else is restricting it, just atmosphere. The cat pipes restrict the gasses, the tiny openings of the collectors(the ball connection(I'll measure that soon from a spare pair I have handy)), the two connections at the back of the cat pipes, the muffler, resonator and the 2.25" pipes.

Why is it hard to grasp what a dual exhaust is? Go back 30 years and everyone understood that it means dual paths for the entire length of the system, end to end. The two banks of an V8 don't constrict down to one pipe at any point, there's two paths throughout the system, which means two flow capacities. With any drop to one path, that cuts the flow capacity in half.

One muffler with a 2.25" outlet(doesn't matter how many input or how big they are), has the total flow potential of one 2.25" pipe. Two mufflers with a 2.25" outlet have the flow potential of two 2.25" pipes, double the flow of one muffler of the same size.

I don't know where you got that single exhaust system chart from, maybe someone made it from a dual chart. But find the common charts for dual exhaust power ratings, and divide those hp numbers in half. So you want to know what a 2.5" single muffler and tail pipe is good for, find the dual 2.5" line listed in those charts, and divide that power by two, that's what a single 2.5" exhaust is good for.

You seem to suggest that the power is determined prior to the muffler, and having two mufflers won't have any effect on power. If that was true, than the one muffler also has no effect on power, and three or four would also do nothing. That should also mean that a single 2" muffler would also not change the power. I don't buy any of that. I bet anything that removing the muffler and tail pipe(which also has a restrictive resonator), will increase power.

Now of course that is after proper tuning of the PCM program, every change alters the A/F ratio. Thus every report of power gains or losses, are inaccurate. The true change isn't known because nobody tunes the PCM(so rarely that it's an accurate generalization). Changes of airflow do not affect the fuel flow in the precise same amount, thus the A/F ratio is too lean or rich depending on what changed. Someone unbolting their exhaust and reporting results of any kind, is meaningless without re-tuning the computer.

 

[vroomzoomboom]

for what its worth, my old set up
302 home ported heads and lower intake, stock foxbody cam, tmh's and a ee m90 supercharger kit with the bone stock exhaust minus rear cats, with a flowmaster 40 and 2 1/2 tail pipe
dyno'd at 245 hp and 321 tq
same setup, one year later with 2 1/2 exhaust to a duel in and out muffler and no cats
dyno'd at 251 hp and 328 tq
that was a modified set up. if your stock and thinking your going to gain gobs of power and torque, dyno's dont lie.

 

[damarble]

nobody tunes the PCM

Even Rick Gusse, who is known as a top notch 5.0L tuner, said it didn't matter that I had a full exhaust (OBX headers, 2.25 duals with H pipe, dual MAC mufflers, 2 deleted cats) when he wrote my tune. So yeah I guess nobody does.

 

[Centaurus5.0]

which includes the inlet and exhaust parts(all of them). The front accessories are parasitic losses, as is the transmission, TC, axles etc. That's obvious stuff to car guys, and an engine dyno measures power without those restrictions, and without the exhaust restrictions, but with headers on.

So the most you can hope to make from any designed exhaust system is the factory's base engine rating?

Why is it hard to grasp what a dual exhaust is?

Why is it hard to grasp you don't need one? Wouldn't a dual system increase surface resistance (and weight) over a single and thus become counter productive? Again, we are talking about street driven 302's with a truck cam thats all done around 4800rpm.

You seem to suggest that the power is determined prior to the muffler

No I ain't, you are. "It's all in the header design"

I bet anything that removing the muffler and tail pipe(which also has a restrictive resonator), will increase power.

Maybe you can find that out for us when you dyno yours in Feb.

 

[Centaurus5.0]

Do you ever wonder why auto manufactures put single exhausts on trucks and duals on car when using relatively the same engine.

1.) Trucks are designed (with cam and single exhaust) to make their power at a lower rpm (torque)
2.) Performance cars make power (with cam a dual exhaust) at a higher rpm (horse power)

You don't need the same flow for low rpm (single) as you do high rpm (dual). You lose velocity with too big a system. That is not a myth. You can't just "tune back in" the torque you lost when going to a giant exhaust. Can't have it both ways. An engines power is a collection of compromises.

 

[Centaurus5.0]

Sorry Don. I'm not trying to pick on you, just trying to figure out your reasoning on this. Sounds like you have a theory that needs to be validated by a dyno, which your planning on. I just don't understand why everyone isn't putting 3" dual exhausts on their 300hp bolt on foxbody mustangs if showed even a 5hp gain? Because no one in the county knows how to tune a car right?

 

[CDW6212R]

Sorry Don. I'm not trying to pick on you, just trying to figure out your reasoning on this. Sounds like you have a theory that needs to be validated by a dyno, which your planning on. I just don't understand why everyone isn't putting 3" dual exhausts on their 300hp bolt on foxbody mustangs if showed even a 5hp gain? Because no one in the county knows how to tune a car right?

302 Mustang guys are installing bigger exhausts than stock, lots bigger, and the fastest ones have at least dual 3" exhausts.

 

[Dono]

As far as I can tell, you guys are saying the same thing. Just approaching it from different angles.

If your giving the motor as much exhaust as it needs, more gains won't be found from going bigger.
Its true that more air flow thru a same sized motor raises the power band, and increases peak hp (less hp and torque down low). This can be seen with intakes also.

This gets really muddy since it also depends on the cam you have, and how much overlap in the lobes. Lots of overlap means with a restrictive exhaust, you will probably not get all the exhaust gasses out of the combustion chamber (or, it gets out and is pushed back in thru reversion). Factory cams have little overlap,

In my case, with a rear mount turbo...No gain in big exhaust. The turbo is the restriction. I would probably benefit from a small single exhaust to the turbo at the back of the truck. My cam was designed with very little overlap, as we knew the exhaust would be restrictive when the cam was designed.

Look at Tim's example of going with a big exhaust to try to relieve back pressure. He gained, but not what he or anyone else would have expected. TMH's are small, we know that. They are well designed, but small when lots of air needs to be moved.

I really want to see Don's testing, and how he goes about the exhaust. It will all be really interesting.
On tuning, it depends what a/f ratio you want. I 'think' having a motor that flows more air at the same rpm actually makes the mixture a bit more rich. I could be wrong, but I'm pretty sure this is the case. @4pointslow will be able to tell us shortly (were all impatiently waiting as he finishes his head/cams install). If what I think is true, more power would be made from tuning and leaning the wot mixture out a bit as factory tuning is a bit rich for best power, and we just made the mixture fatter. Out of wot, the computer will definitely use the 02 sensors and adjust for pre-programmed commanded a/f ratio.

There's my thoughts guys. Maybe not 100% accurate, but its my 2 cents worth based on my experiences.

I'd also say that the thoughts on all the other modifications are pretty dead on as far as not being able to change just one thing. Make one mod, and you have just set off a waterfall of changes that need to be made.

roller rockers + springs + modifying valve cover's (or replacing).
347 = damper dudes 28oz damper for explorers - easily ordered
-No real reason to go 347 unless you get heads to flow better (ported, or replaced). Then you really need to do something with intake and exhaust get the gains out of the bigger ci motor (Intake and exhaust need to be able to flow more air so they are not the restriction).
Its one big can of worms.
I would encourage everyone to do this as misery loves company, lol
The good news is that my combination is stable, and making great power.

 

[Centaurus5.0]

Thanks guys for the input so far!

I updated the Rockers and Strokers section.

 

[delexploder]

aside from headers my exhaust is about the best it can be in a second gen , 2.5 inch magnaflow direct fit cats , ball flanged to a dual in / out magnaflow muffler still 2.5 inch and basically its an x pipe , see through no baffles , i then used 2.5 inch magnaflow dual tails meant for a ranger with stainless step band clamps at the muffler, had to cut on the straight parts and rotate to reindex the bends , im exiting between the frame rails with 3 inch 18 inch long magnaflow tips , not a clue if it makes any more power but it sounds great doesn't drone and comes apart very easy, and will support anything i could ever do with a sbf in this chassis , btw my previous tail pipes exited outside the frame rails and at that time i still had a hitch also and no problems with the spare tire

 

[Centaurus5.0]

@delexplorer

Cool!

Do you have any pics of your setup?