Just thought I'd let everyone know how removing the factory muffler and tailpipe affected my ET. I already posted my timeslips after installing the SuperChip and I thought you may want to see how this additional mod worked out. The following shows the difference in the two best timeslips before and after the stock muffler and tailpipe was removed. Corrected ET's are in my signature.

----------before-----------after-----------

60'------2.387------------2.410
330'----6.938------------6.939
1/8-----10.746----------10.724
MPH----64.47------------64.93
1000---14.029----------13.982
1/4-----16.804----------16.736
MPH----81.17------------81.75

"before" was at 74 deg, "after" was at 69 deg
I reset the computer and drove 150 miles before getting the "after" timeslip

As you can see, I lost ground from the starting line to the 330' mark. Maybe due to a drop in torque or a shift in torque upwards in the rpm range so that I lost a little mechanical advantage because of converter stall speed or simply track conditions, staging depth, tire pressure differences.

By the end of the track I recovered that lost ground and picked up a little time.

Summary: The good news is you definitely won't lose power by running straight pipes and if you do loose a little low-end torque its negligible.

As a sidenote, the exhaust sounds really good. I think buying flowmasters or glasspacks is a waste of money, it sounds the same to me. I am going to fabricate a section of straight pipe to install and keep my stock exhaust so I can swap them in and out whenever I want. Plus, its lighter.

If I was planning on keeping this truck more than a year, I would probably look into getting a catback systems with dual exhaust and a x-pipe. I would definitely ask others for timeslips to see how much it actually improved their time first though.

 

So are you running nothing besides cats??

 

S&B,

that's right... factory exhaust manifolds, cats and y-pipe

removed stock muffler and tailpipe at the joint underneath the rear seat

 

Hi Eric,

Thanks for your post!

You do have a 5 degree temperature difference there, and all else being equal, at those temperature points you've got a tad more timing at that lower temperature (very small), as well as the air being slightly denser, and those factors are more likely the real reason why you saw a slightly quicker 1/4 mile ET.

I do agree that the loss of low end torque from the straight pipes certainly hurt the acceleration of the vehicle for the first couple hundred yards, that has always happened in any of the back-to-back comparisons we've done as well, you called it to a T.

You will lose power on the low end (below about 3000 rpm) by running straight pipes like that, and you also won't make as much power with straight pipes as you would with a properly flow engineered cat-back exhaust system, just as you commented on in your post.

The loss of power (specifically, torque) below 3000 rpm caused by straight pipes and most cat-back exhaust systems in these vehicles is generally not tolerable to most vehicle owners in these heavy trucks (though some owners are fine with that), as that causes more throttle opening to have to be used to get the vehicle moving and to accelerate it, so fuel mileage generally drops a bit along with performance below 3000 rpm.

Out here in the country where we are, it's a very rural area one of of, if not the poorest country in Virginia overall, so pay scales are lower and unemployment higher than average, and as a result of the economic conditions here a number of truck owners won't put a properly flow engineered exhaust system on to get the best results, but will instead just run straight pipes back from the cats so they can get some sound. That does give a better sounding exhaust than stock (louder mainly), though clearly not as much power is made as with the stock exhaust system up thru about 3000 rpm, as the factory 2.5" single system is designed specifically to produce maximum torque below 3000 rpm. Over 3000 rpm you will pick up a few more hp over the stock exhaust by running straight pipes, but you still don't make as much power as with a properly flow engineered exhaust system.

Interesting results, thanks for your post & congratulations on once again lowering your best ET!

 

I really want to get to the track, but since test n tune nights are wednesday & Thursday, and I work both of those nights LOL

 

Hi Beastie,

Well, on the bright side, you do live in the South, where tracks are open later in the season than for most people who live at higher latitudes. So you've got a longer season during which you can do some testing, etc. compared to most people, maybe you can get one of those nights off, or just drive further away from your area to find a track running on the weekend, or any time you can get offf work, etc.

This time of year, just before the tracks close in each area, is usually when people see their lowest ET's of the year, of course this is due to the combination of weather conditions (colder air being denser, engines make more power) combined with the modifications they've been working on all year.

Good luck getting to the track!

 

Just hoping to get others to post their slips...

Back in Oct, I ran out at Gateway Intl Raceway on a cool/dry night with little or no wind. According to observations from the St. Louis Downtown airport about 4-5 miles away, the temp/dewpoint was ~09C/02C and the sea level pressure was in the ballpark of 1016.7 millibars. Anyone want to correct my times to a warmer climate/lower pressure? Or does a website exist that would do this?

I ran 3 times, with each run more or less identical except for the reaction times. This was my first time at the track...I couldn't believe how time just seems to sit still when you are staging. The first time I was up there I recall having the adrenaline buzz of my life and then I remember seeing the light go green all of the sudden from seemingly out of the middle of nowhere. Of course for those who know, if you haven't hit the gas by then, you've missed the boat. At any rate, I pulled a stock-ish Z-28 (15.283@97.12) out to a little short of the 1/8 mile mark after leaving the hole about .2 sec after him, ran a tight race with a riced up Pontiac Sunfire (16.608@83.02) but was always ahead the whole time, and I got royally wasted by a modded Z-28 (13.246@104.32). Here's a tip...if the Camaro driver next to you is wearing a helmet and you aren't--don't expect to pull him off of the line. Didn't see a whole lot of other trucks out there except for Lightnings and 3-4 modded 5.9 Dakotas. Since I was about the only non-blown, non-N2O'ed stock looking truck out there, I got a few good comments from the announcers concerning how quick I was off of the line for my 2nd & 3rd runs. That was pretty neat to hear coming over the radio while staging.

I have a 5.4L '00 F-150 ext cab, short box 4x4 with the auto & 3.55 gears. The short mod list includes the Superchips Microtuner, a K&N filter in the stock intake & airbox, and I too have a straight pipe in lieu of the stock muffler. I don't have any before/after times in regards to the exhaust mod, but it did seem like it lost low-end power for awhile but picked it back up after a hundred or so miles of driving. I also have a soft tonneau cover...and my next mod will likely be an electric fan kit. Oh, and I did get 18mpg with it on a very flat 150 mile trip @ 65-70mph.

Here's the times for ya...

60' 2.389
330' 6.769
1/8 10.473
MPH 66.37
1000' 13.670
1/4 16.393
MPH 82.37

Folks, if you've been wanting to get out to the track but you're embarrassed to be running a "slow" truck...grab a friend and JUST DO IT!!! I swear the fun you'll have will be well worth it. The bench racing and the stuff you'll pick up from the car guys will be just as fun as the rush you get when you pull up to the line...

Plus it was neat seeing my friend in his Mustang GT with his new Bassani x-pipe and cat-back run well into the 14s. Installing that baby was sweet.

Anyway, gotta go--I've already wasted enough bandwidth...

Jon

 

good car math website, use it to correct your ET to standard conditions

http://www.prestage.com/carmath/default.asp

you're right about the adrenaline rush, most fun I've ever had for $10, except maybe a 12-pack

 

Glad you enjoyed the post ericj!

Sometime I think I'll have to revert back to the stock program in my F-150 at the track to see what kind of improvement the Superchip made for me. It won't stay that way for long though! My seat o' pants meter agrees with the ~3/4 sec improvement that you observed. All I can say is I just love it when my 5.4 starts singing around 2800 RPM and up. It comes alive with a powerful rush in 1st and 2nd gear...and the shifting improvements undoubtedly help out in the ET dept as well.

That website you hooked us up with is pretty handy! From it I gather that I would run 16.46@81.95mph at STP. From my meteorology texts, that corresponds to a temp of 288K and a pressure of 1013.25 hPa. Or for the English unit types here in the US, that comes to about 59 deg F and 29.92" of Hg. Nonetheless, it sounds like a reasonable computation given the conditions that I ran under. Can't wait to get the electric fan kit...but I've been way too busy at work to be able to take on that project for another few months.

Now I just need to figure out exactly how much weight I'm launching down the track so I can compare w/ the car guys to compare estimated HP numbers via ET. I'll have to find a friendly grain elevator somewhere around here to accomplish that. My last truck (a '92 F-150 4x4 reg cab short box w/ a 302 auto and 31" tires) came to about 5300 pounds! I don't see how my '00 ext cab could be any lighter unless the newer trucks are made of alot more plastic!

As for the straight pipe setup, I agree that there's a better way to do an exhaust from an engineering standpoint. However, after helping my friend install his Bassani high-flow cats, x-pipe and cat-back, I don't know if I could get myself to just do a cat-back for the money it would take with respect to the performance and sound improvements. That system was just too clean and too sexy (I'm not kidding here!) for what it did to his car for me to just slap on a cat back without doing it right and getting rid of the nasty bends behind the cats on my truck first. Unfortunately, I haven't seen any high flow cats, x-pipe and muffler setups like that for trucks. I know that free flowing exhausts aren't conducive for low end torque (I still tow w/ my F-150 w/ no complaints), but I wonder if the stock cats going into a 2.5" straight pipe would have about as much backpressure as 2 higher flow cats, an x-pipe, dual 2.5 exhaust pipes & a somewhat restrictive dual muffler setup. Thus my hypothesis is that the backpressure on a hi-perf exhaust w/ mufflers like on my friend's GT would be comparable to a truck w/ the stock cats and a straight pipe...so why not have a freer, straighter flow exhaust design like that for a truck with the right amount of backpressure built into the cats and mufflers to keep most of your low end torque but let you flex your muscles on the mid/top end moreso than what's currently out there? Mike T et al, if that last section made sense, do you have any comment on that line of thinking? After going to the track and seeing the sea of Mustangs and Camaros, I can see why companies offer properly designed exhausts like that for lighter weight performance cars and not trucks. The demand just isn't there. Ah, what a catch-22 showstopper. I'm thinking of trying something like that in the future (after the electric fan), but I realize it could be a spendy custom job. And it still most likely wouldn't be as well engineered flow-wise as would be a tested offering from someone like Bassani, Magnaflow or Flowmaster.

Is that line of thinking feasable? Or is the backpressure provided by the nasty bend and the stock cats and single 2.5" pipe significantly more than what would be found with the higher performance setup I described above?

FWIW, I don't really find the Flowmaster sound that appealing on other trucks that I've heard. I haven't really heard any other setups though in person, so I can't say anything about them in comparison with what I have now. Yes, the straight pipe route is a little brash at WOT, but at other throttle settings I feel it's pretty tough to beat.

Just looking for a good discussion here,
Jon

 

Hi Eric & Jon,

Great posts you guys, especially Jon's description of going to the track. Thanks *very* much to Jon for encouraging more F-150 owners to get out to the track regardless of what kind of times their vehicle may run or their experience level, absolutely!

In fact, if you look at this months' issue of MM&FF (that's Muscle Mustangs & Fast Fords for the uninitiated), you'll see that in Top Truck class, the season points leader drives a 19-second F-150!!!! He leaves as much as 6+ full seconds ahead of some of his opponents, who then have to run him down and can only start after he has left 6+ full seconds earlier! So they have to not only cut a tremendous light, but also have to run him down without breaking out; as a result, many of his opponents red-light and/or break out (run under their dial-in time) against him, so much so that he's killing everyone at the track with his way-slow 19 second F-150. You don't have to be the fastest car or truck to win, and you don't need to win to have fun, just get started with what you have, and you'll have a blast. We get a lot of first-timers at the track every year at our National Rally, and it's always fun for them, they grin from ear to ear and can't wait to get back.

Talk about the great equalizer, bracket racing is for EVERYONE!

So it doesn't matter *what* times you run, and it doesn't matter that you've never run before; what matters is that you get out there and have fun getting some experience, as everyone has to start somewhere. All you need to do to win is cut a good light and dial your ET in accurately, and you can take on the fastest trucks & cars and still *win*, even at the National level.

I loved the descriptions by Eric & Jon about the adrenaline level the first few times at the starting line, that describes my first efforst to a T. Heck, I *still* get that way sometimes, especially if I'm up against someone I really want to blow away. It's all part the fun!

Now, on to your exhaust........................

First, we can't go into detail here, this isn't the section of the boards and it's just too involved to type it all out on a message board of course, so just very briefly.................

Remember that backpressure does NOT equal torque, as so many claim, including muffler shops, even some exhaust system manufacturers & "experts" often claim this. Backpressure contributes to reversion during overlap (of course this depends on platform & cam specs, too), but more backpressure does NOT automatically increase torque. Now, you just *might* happen to make more torque with more backpressure in a given situation, but not because of the backpressure, that is just coincidental; more torque was amde because the resultant *velocity* was higher without being overly restrictive, that's all.

*Velocity* yields torque, so keeping the exhaust flow *velocity* as high as possible without excessive backpressure is the key to getting power gains throughout the entire rpm range. In these heavy trucks & SUV's, the torque below 3000 rpm at *any* throttle position is far more critical to driveability and overall performance both on the street and at the track than big pipes flowing big numbers & yielding power gains only above 2800-3000 rpm. That being said, you can indeed "have it all," with a properly flow-engineered system.

The factory 2.5" single system in the 1997 & up F-150 is actually designed to provide maximum torque on part-throttle below 3000 rpm, specifically, and it does this very well indeed, at the cost of both horsepower and torque at heavy throttle, and at almost any throttle position beyond about 3000 rpm. And this is, in very general terms, why the vast majority of aftermarket cat-back systems or exhaust mods cause hp gains at higher rpm, but kill torque below 3000 rpm at virtually any throttle position. How does this happen? When the flow is opened up without proper flow engienering to maintain spent exhaust gas velocity, you lose the scavenging effect that helps to pull spent exhaust gases from the cylinder head, and *that* is the specific mechanism that causes the classic loss of torque so many people complain here about after exhaust mods.

For example, someone pulls off their catalytic converters completely.......what happens? Well, you pick up a few hp at higher rpm, but you *lose* power compared to what a proper set of high-flow cats will deliver anywhere in the rpm range, as you're taking a lot of heat out of the exhaust. Heat is another major component that we want to keep as much as is reasonably possible in the exhaust as it aids velocity. You will generally make more power with a set of Magnaflow high-flow cats as compared to no cats at all in these trucks, as hard as that is for some to accept, we've seen it time after time.

For most lightly modded F-150's , the best way to go is to simply use the Magnaflow cat-back system, we've seen the highest peak hp gains over even true dual systems like Spintech's 2.5" true dual setup, as well as it being the only cat-back system we've ever seen to actually increase torque *everywhere*, literally at any rpm and at any throttle position.

Now, as power levels get higher (or for those who will spend what it takes to do it right), using the proper components in a true dual exhaust system can and will accomplish the same thing, literally increasing both horsepower and torque *all* the time, at any throttle position. It won't happen by throwing cheap components together of course, and yes, that is more expensive as it involves new cats, X-pipe, new mufflers, etc., as well as your local muffler shop to weld up the new components, but we can indeed provide the components for a true dual exhaust that will deliver very significant power gains *everywhere* in the rpm range and at any throttle position. Most recently, we've done that for Neal & Beastie, for example, with Neal having a '99 & Beastie having a '95, Neal uses our long-tube headers (the complete setup from exhaust port to tailpipe, in other words), and Beastie is running basically the same setup without the long tube headers since his is a pre-'97. And in both trucks, the owners immediately saw more power everywhere, off the line, thru the midrange, and on the top end.

So it *can* be dione, we can supply an exhaust that will do the job no matter what your power level is at in the F-150.

This is just some quick info & thus very basic, Jon, so if you'd like to give us a call I'll be happy to go over this with you in detail.

Thanks again for your posts & good luck!