exhaust velocity...

[Hawaiianbasshead]

ok, so I want to see a thread focused more on exhaust velocity than anything else.

What are ways to improve it and really want to know how to keep it up with larger diameter piping..

I can see how free flowing exhausts would have higher velocity, BUT are there ways such as coating with ceramic or adding cats and such that will get me better velocity by keeping the heat up and having a TRUELY tuned exhaust?

would love to get insight as well as have some for others. here's my personal dilemma! I ordered a flowmaster 2.25"in/3" out Y pipe and a 3"in/out powerstick so I'm looking at loosing power low in the rpm bandwidth as it stands from what I've read. so I'm trying to figure out how to avoid that as much and in the best possible ways. from my calculations a single 3" has less diameter than dual 2.25" pipes anyway, so really I shouldn't be flowing more than ANYONE with duals really since I don't think anyone running duals has smaller than 2.25" pipe. I got it by using the, pie*radius squared method and came up with (examples being all interior diameters) 2.25" pipe 12.47 square inches of surface area, 2.5" 15.42in^2 and 3" at 22.1841in^2 so 3" has less surface area/flow than dual 2.25" and quite a bit less than dual 2.5" so how much loss I'm facing should be less than alot of people. considering the majority run baffled mufflers, lots of bends and some run duals none of which I believe are smaller diameter than 2.25"... any thoughts on my problem or MOSTLY anything concerning velocity would be awesome thanks to all who partake

[HawaiiTitan]

Sup bro.

Honestly I don't think your gonna loose low end like you might think, you gotta remember you have headers now, so allot more velocity already.

But we can disect this starting from the collectors, what are the collectors diameter? 2.25?

[O-FiveCC]

Hey man, you are going to have loads of low-end with that setup. Trust me, I run the same size piping with a flow-through muffler and no cats and run 1.92 60' times on stock tires and 8.7 1/8th miles. I always recommend 2.25 into 3" as the nest performing set-up, along with a few other members. I have seen a lot of set-ups run at the track, the cats IMO aren't really going to help with velocity. IMO coating isn't going to help enough either. I did not get my headers coated and is has not hurt my performance at all. There really is no way to keep the velocity up with larger piping, thats why some of us always try to steer people away from y-pipes such as the Banks. But in any case, you will not be losing any low-end power with that set-up. As a matter fact, you should have too much to use LOL. Give it a try and report back to us

[mmtitan]

mmm a nice sound clip would be well appriciated when you get that power stick !

[teksupportdude]

Originally Posted by mmtitan

mmm a nice sound clip would be well appriciated when you get that power stick !

i second this movement, id love to hear that sound clip...subscribing.

[Toughtitan08]

You should have a pretty close to ideal setup. If it were me, I would have went with dual 2.5" to a single 3" or 3.5" for the good midrange and top end. The diameter has to be figured with engine size and intended rpm range. I like to haul a*s so that's why I have the setup I do. If I were to have run a single, it would have been the dual 2.5 in and single 3.5" out with a Magnaflow or Aerochamber center in/out. A single 3.5" has less area than the dual 2.5" so it matches perfectly.

[Hawaiianbasshead]

ok, so a problem isn't with the secondary side of the Y but the primary side being too large, say if it were 2.5" and pre-Y piping were 2.5" THERE lay the start of a problem?

isn't the JBA Y pipe a 2.25" in/2.5" out? I figure a step down from dual 2.25"s into something like that would be good. honestly I feel I lost a decent amount of low end with the headers not sure if it's the secondary cats or the fact that I still have the stock Y pipe a combination of both or what. So I want to GAIN low end back at this point really, so I've been even considering something as tight/small as the Zoomers catback. just to get that low end, throw the tires off the rims tq back lol. I don't need pull over 60mph so I'm thinking I'm gonna change back to my premium gas tune on the BD PP throw the aFe back on, and this new exhaust and see where it leaves me. Eric says it's not too late and he can still make me a 2.5" stick instead he said it'd be quieter but he really doesn't see any performance changes as they're both flow thru, I tried to tell him I will also run 2.5" pipe if I get the 2.5" stick to see what he has to say about it.

really I want the most possible low end. and imo really no matter what I do, I WILL get more upper end than I have now as no matter what it'll have more MAXIMUM flow, so no matter what my upper end will step up when I change the Y pipe and flow thru muffler as well as a little less bending/backpressure. When I ditch the rear passenger side out and just straight dump before the axle. I have over 90* of bending after the muffler at the moment as well as slightly larger diameter secondary piping. I also want to change the piping from the B pipes if I remove the cats I'll want to run 2" piping there from what I've seen you post 0-Fivecc. or possibly just gut the secondary cats but I think I want new piping throughout as it's rusted up anyway.

from a little searching, I'm confused on the JBA catback, some places say 2.5" into 3" and one is saying something like 2.5" into 2.5"

thanks for all the help, I'm starting to think the 3" is gonna be fine. but I still can't help but to want stupid amounts of down low power that I'm lacking right now...

[HawaiiTitan]

Just to touch up on our conversation last night, I think if you go with 2.25 piping removing the stock secondary cats, then your 2.25 y-pipe that merges into 3'', then 3 inch powerstick that dumps, it would be very close ideal for low end for a single set up.

You really should run the same diameter piping as the header collectors which you said is 2.25 (I'm still a bit confused why they made the collectors so small, I would think they should be atleast 2.5 inch with 1 5/8 primaries but thats another topic) on the midpipes/b pipes to keep velocity up. I think that if you go with 2.5 inch piping on the midpipes, your low end will suffer but your mid to top end will be better. Also if you go for a 2.5 merge on the y pipe you'll have lots of low end, but your gonna start snorkling already from midrange, top end your power will fall off bigtime. So honestly I think what you originally have planned is a good set up for low to midrange.

You gotta remember the amount of velocity you will see when you remove the secondary cats will be allot, keeping the midpipes the same diameter as the collectors will keep velocity up for the area that header is tuned for, and a 3 inch merge has a smaller area than the two 2.25 pipes. When it gets to the 3 inch merge theres so much pulses coming from the two banks that by midrange it's the perfect diameter to be big enough to flow well but not too big to slow velocity down. I do think the top end will be hampered by that diameter but since your looking for low-midrange I really think that's a good set up.

Your other crap behind your headers is what is killing your power right now, all that needs to be changed out, also I highly suggest removing the secondary cats.

Later bro.

[O-FiveCC]

The JBA is a 2.25 into 3"...it is one of the MOST ideal set-ups for our trucks. I have seen countless set-ups run on these trucks at the track. The y-pipe and b-pipes are very important. Look at my mods, and there are guys that I race against who run slower times with a PGM and Cams. Now who I speak of is about 250LBS heavier than me, but still, he should be able to eat me with PGM and Cams. He runs 2.25 b-pipes and a 3" y-pipe. Now he's gone with a diff set-up but he hasn't ran it yet. Even Papa_D had Cams and ran the Zoomers 2" into 3" y-pipe and won the Old Town Dyno award pushing out over 340 HP. So it appears the 2" into 3" flowed pretty darn well for his cammed Titan. If that small of a y-pipe flowed that well on a cammed truck, then there is no need to go much bigger on a non-cammed truck. For an all out top-end assault I would suggest 2.5", but thats not hat your after. My JBA with Nismo headers and no cats, give me IMO about the best low-end/mid-range you can have on a bolt-on tune Titan, but it falls off slightly on the top-end compared to an equally modded Titan with Nismo Tru-Duals (Pinoytitan)...But I kill him on the low-end!! LOL...Go 2.25 to 3" if you want a lot of low-end

[O-FiveCC]

I agree with Hawaii Titan to get rid of the secondary cats. I would run as few cats (restrictions) as possible. I don't have inspections here, so I just run no-cats. Also, I wouldn't go any larger than 2.25" b-pipes. The OEM b-pipes are 2", but they crimp down to 1 7/8" after the cats I hear. I am going to go with a straight 2" b-pipe. I think the 2.25 would be more beneficial in the top-end. I know it seems odd to step back down to a 2" after the header collector is .25" larger, but I'm not so sure we are flowing enough to totally fill-up or totally use all that 2.25" in the collector. Basically, these just come from my experiences of racing along with many other Titans down here, the 2 fastest (both 13.8 trucks) have OEM b-pipes with OEM resonators in them, LT headers with no cats, and one has the Nismo Dual cat back (best of 13.88) and the other (me) has the JBA catback (13.84)....Even though the 13.88 guy was a few hundreths slower, his MPH is usually .3 higher though

[themaildude]

Nice to see your video back in your sig. I had a time uploading it.

[O-FiveCC]

LOL, yeah thanks man, I'm not taking it out this time LOL, I don't want to lose it

[Hawaiianbasshead]

thanks for all the pointers guys.

from the searching I did with google on exhaust velocity vs backpressure I learned a little of what I already figured since everyones helpful posts . for an optimal exhaust you need to get as close to zero back pressure possible (keeping flow capacity in mind) while maximizing exhaust velocity for the proper rpm/band that you're aiming for (for the scavenging to be at it's most efficient). which I really already understood. now that I understand it, I just have to figure it out via trial and error and what shared experiences I've found here and on the other T sites can't WAIT to get it all situated and at least on it's way lol.

I'll start by gutting my secondary cats, getting new 2 hole flanges and all new 2.25" piping to the new 2.25" Y, then new 3" out to the 3" powerstick and experiment with home made B pipes later, my buddy has a bender and welder so I'll go play with his shop setup and see what I can do. I use pnematic pipe benders at work and have personally bent lots of 90*s as well as offsets on pipe upwards of 4" ridgid metal electrical conduit is mostly what it is, as well as PVC and other piping. I'm capable of bending and I have attempted to weld a little but since my buddy is a much better welder and it's his machine and shop I'll just let him do that part I'll definitely get vids of it good or bad lol

[O-FiveCC]

Let me know what you try as far as b-pipes and how they work out

[layer1]

Yes. I would be curious as well on the b-pipes as mine are stock.