Why didn't headers make any power?

[04DSGTUNDRA]

I just got Gibson Headers, and Gibson catback exhaust on my 04 v8 tundra. I was under then impression headers gave you the most hp of any mod (bolt on), and am sorry to say they didnt do squat for my truck! the only diff. is the trucks really really loud. Headers are Stainless Steel, and I chose the Dual Sport exhaust (single exhaust with two tips on one side). It sounds just like a 5.3 silverado with a 2chamber flowmaster. As for my truck, its a stock 4.7, with a k&n drop in filter. When I was stock with just the drop in air filter I could pull even with my buddies 05 tacoma 4x4 doublecab, now after headers and exhaust, i still pull even with his tacoma, sometimes i even lose!!! any idea's anyone? i ruled out the k&n being a problem, i reset the computer by disconnecting the negative battery terminal, and have driven with this setup for about 150 miles. what do you all think?

[HBjeff]

i dunno. if we were talkin about lowend power you probably lost any header gains with the catback, but in the highend you should have gained some power.

[RockyMtnRay]

Originally Posted by 04DSGTUNDRA

any idea's anyone? i ruled out the k&n being a problem, i reset the computer by disconnecting the negative battery terminal, and have driven with this setup for about 150 miles. what do you all think?

Originally Posted by HBjeff

i dunno. if we were talkin about lowend power you probably lost any header gains with the catback, but in the highend you should have gained some power.

HBJeff is undoubtedly right on. I'm personally not surprised you lost low to mid range torque (what you need to out accelerate another truck). What you may have gained (and may eventually gain) from the headers has been more than canceled by the catback system.

First, it takes the ECU around 500 to 700 miles to adjust to the headers...including at least 10 start/stop cycles of the engine (fuel trims are only transferred from short term to long term memory during shutdown and then the short term trims are erased). So header gains, if they happen, will take a while...and 150 miles isn't anywhere close to long enough to know.

2nd, there is no body of evidence yet that Gibson headers will produce any torque gains. Since they're basically another JBA clone (like SS Autochrome) and a decent brand, they should improve torque but that's not yet been proven. However since it's unlikely the Gibson headers have features like JBA's "Fire Cone" (which smooths the flow in the collector and prevents the gasses from overly expanding there), I would expect the Gibson header torque curve to look a lot like the SS Autochrome curve. And that in turn means header effects, if any, won't start until the engine speed gets above 3200 RPM or thereabouts...too high to help in the low end. By comparison, JBA headers "kick in" at about 2800 RPM with the stock exhaust and I'm seeing my JBAs kick-in at around 2500 to 2600 RPM with the Gibson muffler (not catback...see discussion below) that I'm using.

3rd, I've yet to see proof that any catback system will improve low end torque since virtually all (maybe ALL) are tuned for horsepower gains in the high RPMs. These exhaust system makers have learned that the only thing most guys look for is HP. And they also know that most guys equate larger pipes with more "power". Unfortunately most guys don't know that tuning for HP usually means large pipe (2.5 inch or more) which really hurts low end torque.

4th, the Gibson Dual Sport exhaust "system" is designed mostly for noise/appearance and Gibson all but admits on its website that it won't do squat for performance, even on the high end. But this "system" is just about guaranteed to significantly hurt your low end "grunt" torque. A Gibson muffler (NOT catback) can significantly improve low end torque...I'm getting excellent low end torque improvements from the Gibson muffler I had installed on my truck. But it has to be right muffler (I'm using the big Gibson "universal" muffler...24 inch long, 6 inch diameter) that will work properly with the harmonics of the headers. This is not, however, a muffler to use if you want a performance sound...it's not much louder than stock.

So, bottom line, you should have installed the headers first and driven the truck for at least 700 miles before doing anything to the muffler. That way you would know exactly how much improvement, if any, the Gibson headers are making...and at what RPMs they will make an improvement. Secondly, unless you are really thrilled about the sound of the Dual Sport catback, I would strongly suggest you immediately re-install the stock exhaust. And after about 1000 miles or so, then maybe replace just the muffler (don't use any catback system) with a free-er flowing model. If you want a performance sound and a performance increase, then use a Magnaflow, Dynomax, or Spintech (not Flowmaster) muffler. If you want a performance increase but no increase in sound, then use the Gibson muffler I chose.

[v8Toilet]

I don't know much about the Gibson headers but the JBA, SSautochrome, and TRD headers give you about 15-20 lb ft more torque and 7-10 more horsepower with the stock exhaust over the stock manifolds. It also takes the computer about 300-500 miles to adjust to the new changes before you start to feel the power difference. You should definitely notice a difference like that.

The dual exhaust on your truck is also hurting your power negating the power gains you might get from those headers. When I had similar TRD duals the low end torque loss was enough to make it feel like it had a loose torque converter. I'd give it the gas and it didn't have that snap off the line like it did stock; it basically just bogged off the line.

With an eight cylinder engine the gasses in the pipe flow through the pipe in pulses that coincide with the firing pulses of the engine. With the stock exhaust these gases speed up and slow down through the pipe because of the relatively small pipe diameter but they never stop moving. So long as they are constantly moving each pulse helps scavenge the proceeding one and so on. With duals or a larger single pipe the exhaust volume is the same coming from the engine so the gases flowing through the larger pipe or duals have to slow down because they expand more in the larger pipe. Now the gas pulses actually stop and go at lower engine RPM inside that pipe causing the engine to work harder to pump the gases out of the exhaust system. This causes pumping efficiency losses and therefore torque loss at low RPM and that in turn makes your heavy truck slower especially off the line. Bigger is not better!

What you want is for the truck to get its heavy mass going quickly off the line and you need good low end torque (from idle to 3000 RPM). You want the exhaust pipe diameter to be sized so that you have good low end torque but so that it doesn't choke off the power at high RPM either. Toyota engineers sized the stock 2-3/8” pipe perfectly for that and this is why I recommend to TS members to just change the muffler and not the whole exhaust system. A better flowing muffler with the stock exhaust pipe will give you better low end torque than what you had with the stock muffler. A better flowing muffler on the stock exhaust with headers should give you gains similar to what you see in my signature.

I’ve tested a JBA Evol exhaust system, which has single 2-1/2” pipe at the drag strip and I’ve tested those air filters and none of that stuff makes your truck faster. It just makes more noise! Just by adding a TRD air filter to your stock air box you’ll loose a little horsepower because the stock air filter actually flows more air when new due to having twice the surface area as a TRD air filter or similar K&N filter.

Hope this clarifies things for you. Rockymtnray will probably chime in here too and say similar things. He has a setup similar to what I have.

[RobertT3]

Originally Posted by 04DSGTUNDRA

I just got Gibson Headers, and Gibson catback exhaust on my 04 v8 tundra. I was under then impression headers gave you the most hp of any mod (bolt on), and am sorry to say they didnt do squat for my truck! the only diff. is the trucks really really loud. Headers are Stainless Steel, and I chose the Dual Sport exhaust (single exhaust with two tips on one side). It sounds just like a 5.3 silverado with a 2chamber flowmaster. As for my truck, its a stock 4.7, with a k&n drop in filter. When I was stock with just the drop in air filter I could pull even with my buddies 05 tacoma 4x4 doublecab, now after headers and exhaust, i still pull even with his tacoma, sometimes i even lose!!! any idea's anyone? i ruled out the k&n being a problem, i reset the computer by disconnecting the negative battery terminal, and have driven with this setup for about 150 miles. what do you all think?

give the ECU about 300-500 miles that way it will have time to relearn on whats going on and you should see some gains later on...
In a way you should feel some difference right after the install...when I had my JBAs on I felt whole lot of difference on TQ. power and HP. gains...just give ECU some time and let us know if anything changed...

[04DSGTUNDRA]

hmmm I'll drive it 750 miles and see if there is any difference. Thanks everyone for the detailed responses. As far as the torque, going by the ole butt-o-meter it doesn't seem to have lost any, but then again nothing tells more truth then a dynojet. I forgot to mention, headers and exhaust were FREE!!!! They used my truck for a little over a week for product developement (for the headers) and in return gave me the headers and exhaust. my truck was dynoed by Gibson and they claimed 20hp and 30ftlbs of torque on a dynojet with the headers and exhaust, but I never saw the dyno sheets.... Final realese of the Gibson headers for the 4.7 is expected 8-10 weeks, if nothing goes wrong with mine. Maybe I will take it and dyno it after 750 miles just to see where I'm at.... I'll keep everyone posted.

If anyone is in Southern California and wants a free exhaust, go to gibson.com and fill out the free exhaust offer, they are looking for an 05' Tundra with the 4.7 for Research and Dev. also.

[whateverz]

RockyMtnRay, and V8Toilet are right on the money. I had a magna flow 2.5, then just put on Downey ceramic headers and they suggested 3" from the 3rd cat back and 2 3/4 out of the muffler. So I did it. I talked to another shop and he has gone through 3 configurations on his 05' V8 4runner. He said I should put the 2.5 back on and get rid of the larger tip as it robs a few horses! And he would make a custom Y-pipe (he reported a gain). I read in another thread that the stock (restricted looking) Y, is actually a well designed venturi effect and do not change it (you want that sucking effect out, not pushing). So I think I am going to spend more and replace muffler and ditch the tip. And pass on the Y. As far as the 3" system goes and power...It robbed low end for sure (torque), but if you drive on curvey roads or dirt (below50-60mph)and you can keep it in 2nd and keep it up there, it hits hard. Expect 3 mpg. For everyday driving and better mpg listen to these guys!

I would like more opinions on the whole Y-pipe thing. Torque vs. hp etc. I do a lot of 2nd gear driving on dirt. Fun stuff!

[v8Toilet]

I've tried the SSautochrome y-pipe, which is similar to the JBA Y-pipe and I couldn’t tell a difference other that it seemed noisier. I never had the chance to dyno test that. I had so many problems with it leaking that I'll never try another y-pipe again. The stock y-pipe does look restrictive at first but when you think about it, it's actually a great design.

[supritdeol]

Originally Posted by v8Toilet

I've tried the SSautochrome y-pipe, which is similar to the JBA Y-pipe and I couldn’t tell a difference other that it seemed noisier. I never had the chance to dyno test that. I had so many problems with it leaking that I'll never try another y-pipe again. The stock y-pipe does look restrictive at first but when you think about it, it's actually a great design.

are the ssautochrome headers any good. I just got them, and now having second thoughts about installing them. I use my tundra as a daily driver and go driving in the sand dunes on the weekends. What would be the best performance package(what intake, what exhaust/muffler, and what headers)

[KLS]

Stock intake and stock filter,
SS Autochrome headers, 'cuz you already got 'em,
stock pipe,
Gibson 2-1/2" muffler or stock muffler.


Ken

[Toasted Coastie]

Originally Posted by KLS

Stock intake and stock filter,
SS Autochrome headers, 'cuz you already got 'em,
stock pipe,
Gibson 2-1/2" muffler or stock muffler.


Ken

Exactly.

I bought the dynomax ss ultraflo cat back with 2.5" in and out. Going to replace the pipe going out down to stock size, yet keep the muffler (pipe rusted real bad, and I dont think it was aluminized, and there is a gaping hole in it now). On the dyno, SS autochromes and JBA's were fairly simular, if you look at V8's dyno sheets. The SS is mine, and JBA's his. Stock airfilter flowed better, and I gained HP back when switching from the TRD filter (on the dyno) But then again, I gained HP on the dyno from inflating my tires up to 36psi (they were a little low)

I'm hitting the dyno again after I get my exhaust and O2 sensors fixed (this week hopefully, if I get the time).

V8, did you use toyota gaskets for your "temp" ss headers? Did they seal ok?

Every "custom" shop I went to for exhaust said: "oh yeah, go to a 3 inch pipe on your duals, it'll sound real good." I dont think they got it. The funny thing is, I went to Mienike (sp?) and the guy there was: "if you do duals, drop to 2" pipes. I recomend staying with what you have and dropping to as close to stock on the pipe as we can get it." Which will probably be 2-1/4". So much for "custom" exhaust shops for me. All about look and sound to them. Thanks for all the good info V8

[whateverz]

Thanks v8toilet, that settles it, no Y-pipe for me. I am putting the Magnaflow back on.

supritdeol- I agree with KLS. Put your headers on. I have had a Magnaflow and a XL, but I would get a Flowmaster 40 Delta Flow. Better torque increases I've been told, maybe RockyMtnRay knows more on that. You could increase the pipe from the cat to the muffler to 2 3/4", but keep the out pipe stock (single unless you want to sound cool). You will see a substantial increase, as v8 toilet proved. I also drilled 3, 1 1/4" holes in my stock airbox (bottom) right in front of the washer fluid fill tube. There is a hole there the A/C line goes through that brings in fresh air. I actually noticed better throttle response, and a little power. You can always tape em' over. If you are worried about mud, dust, water etc. put a piece of a foam filter over them (oiled if you are paranoid). As far as water....water injection! (more power) You won't hydrolock unless you are swimming. Just be sure to clean your filter more.

[HBjeff]

flowmaster is not the muffler you want if you are looking for power. yeah they sound the best, but they wont flow anywhere near what a magnaflow can.

[PagalDesi4Life]

Originally Posted by HBjeff

flowmaster is not the muffler you want if you are looking for power. yeah they sound the best, but they wont flow anywhere near what a magnaflow can.

So for performances, its down to the Gibson and the Magnaflow mufflers?

[RockyMtnRay]

Originally Posted by PagalDesi4Life

So for performances, its down to the Gibson and the Magnaflow mufflers?

Or Dynomax (quiet) or Spintech (not so quiet). But definitely not Flowmaster...those things oughta be named FlowRestrictors.