skinny z

I've actually thought of using 3" from the single terminator box to the muffler. 3" pipe will flow about 800cfm (standard test pressure) and that's just enough for me at this point. I would have a 3rd gen application muffler that flowed as much. Then I could use the 4". In your case, because of your power requirements, you would have to fab something along the lines of 5" pipe for the box and 4" exhaust to the back. Is there enough room for 5"?
And then there's the issue of collector length. A terminator box at the closest merge between the collectors (just past the trans) will result in collectors being about 40" long. Most collector extentions I've seen in use are along the lines of 18-24".

Orr89RocZ

iTrader: (20)

Thats going to be the problem. because of the how the pipes need to run, i fear i will not beable to do this exhaust tuning business. there is simple no room for the collector length i need to run. Now Allen is gonna run some numbers thru Pipemax for me to see what it may recommend.

I dont feel a ypipe is for me at this current point. I am 95% sure i'm doing true dual 3inch. i wanted to go over each axle if possible. I also want to run either powerstick chambered tubes like the one i have now or dynomax ultraflow round mufflers for abit quieter tone.

For me it will have to be 2 seperate termination boxes before the x pipe or H pipe if i run that. i wanted a x pipe tho.

true 3inch will be enough. At 2.2 cfm per hp, and if i have upwards of 500-550 hp, thats 1100-1200 cfm. each bank will need half that at 600 cfm or so. 3inch is more than enough and leaves room for nitrous

let me see if i can measure some things on my car to get a better idea of lengths
be right back

EDIT:

Got some numbers here. I'm estimating i got about 20 inches between where the header will exit and my spohn crossmember. If i ran a box, it have to be about 4inches beyond that point so a possible 24 inches plus the length of the header collector itself which seems to be around 8 inches? to the start of the termination box. Collector length of 32 inches may be achieveable with the right dimensions for the box. Shorter will be harder to do

to get shorter i would have to run the 4inch single pipe style if that will work as effective as a box. I have to read that article again and do some more research to see if that is as effective as a termination 'box' style box cuz i can dump the exhaust fromthe header into 4inch pipes for about 3 ft before i have to neck down to 3inch over the axle. That just may work

skinny z

David Vizard has mentioned how empty muffler cases can be used as termination boxes provided you pay attention to how the pipes enter and leave the box. (as 1989GTATransAm has reminded me)
I'm interested to see the results of the Pipe Max calculation. I wouldn't be surprised if 24-32" is far off.

Orr89RocZ

iTrader: (20)

got the results from Allen's pipemax program. thanks again man!

For 6000rpm peak:
1. Best collector diameter is 2.80 inch OD 16 gauge.
2. Best tuned lengths.
A. 18.4" best power and recommended
B. 36.8" best torque
C. 73.7" longest with mufflers.
Note: you can go 9.2". Shortest recommended
Worst lengths are 27.6", 55.3" and 110.5"

For 6200 rpm peak
1. Best collector diameter is 2.85" inch OD 16 guage.
2. Best tuned lengths.
A. 17.8" best power and recommended
B. 35.6" best torque
C. 71.3" longest with mufflers.
Note: You can go 8.9". Shortest recommended
Worst lengths are 26.7". 53.5" and 106.9"


SO if my total exhaust system is 73.7 inches long before dumping to atmosphere, i should be tuned for 6000 rpms?

I want to stick to around 17-20 inches for peaks in the 5800-6200 rpms range. thats where i want my max power to reallly shine, since i SHOULD be shifting at 6400 and rpms will drop back into the upper powerband

If i go with 36inch for max torque, i wonder how much torque is gained and how much hp is lost

Orr89RocZ

iTrader: (20)

About that, it appears the pipes need to enter about 1/2-1 inch inside the case to eliminate reversion effects. Am i understanding this correctly?

I can see the inlet being like that, but the outlet i would figure should taper back into the exiting pipe size or 3inch pipe in my case

1989GTATransAm

iTrader: (3)

Correct on the inlet and as you stated to help prevent reversion. The outlet can be a taper as shown or a bellmouth also as shown in post 39.

I was wondering something that might help you guys. It has been stated the volume of the termination box at a minimum should be 8 times the volume of one cylinder. I was wondering if this is for a car with 8 cylinders. So if one was to have a termination box on each side of a dual exhaust would it only need to have the volume of 4 cylinders? If so that might help in fitting in a box.

I might go over to David Vizards web site and post the question.

Orr89RocZ

iTrader: (20)

Found a great real world dyno test between stock collector length and pipemax determined length

Before with STOCK collector LENGTH


AFTER with PIPEMAX determined Correct collector LENGTH

Orr89RocZ

iTrader: (20)

Thats what i was wondering abit ago..... if you run both banks into one big box, i can see it being 8 to 10 times as large, but if you run only half the motor into a box, it should be half as large or 4-5 times as large as one cylinder. that would be MUCH better for room under the car

1989GTATransAm

iTrader: (3)

That is quite a difference regarding the power under the curve. In fact that is quite a difference. Hmmmm looks like the tuned exhaust is a worthwhile pursuit.

Edit: posted the question on David Vizards web site. Might take a week to get an answer. He seems to be one busy fellow.

Edit: To me it seems one of the sources for untapped power in our cars is in the exhaust system. Maybe the greatest source for new power. I think the guys with the long tube headers have a lot of potential in that area. Later in the year I will try and see if it works somewhat with shorty headers.

Orr89RocZ

iTrader: (20)

yes its up a good bit down at the lower rpms, and around 10hp/tq at peak rpms. i think its worthwhile investment as well

skinny z

I've been pursuing this exhaust potential for over a year now. Most fellows with street/strip cars seem to be content with next larger cam or bigger carb as their next modification instead of exploring whats yet untapped from their combinations.
It's good to see a couple of other guys getting into the technology.
It'll really be interesting to see the results.

skinny z

Not to make it difficult for you Orr89 however the interpretation I get from Vizards books is that the terminator box has to be 8x the volume of one cylinder 'PER SIDE' with 11 to 15 times being better. This would explain why the resonator system he designed for his friends corvette runs the length of the trans tunnel with both collectors entering and dual exhaust leaving. That box must be at least 800 cubic inches.

Orr89RocZ

iTrader: (20)

Thats understandable, i was just making sure. Its still doable if fabricated right

skinny z

Fabrication aside, I may just go the open header route with collector extentions (I'm looking for a copy of Pipe Max) and tune for track days.
I'll talk with my fabrication guy when the car is on the hoist. I will say that if anyone can build the system from scratch it's Tom from Altered Images. He's a drag chassis builder. His custom headers are a work of art but of course it comes with a price. (glad he owes me money!)
In the meantime, I'll be watching to see what you guys are doing.
Good luck.

Orr89RocZ

iTrader: (20)

good deal i hope to order headers this week....i gotta check the funds Once thats done, i can start assembly of the motor and put it in the car to see where the headers dump and how to mod the crossmember. Eh..its not gonna be easy


I'd rather not have cutous with extensions cuz i dont like the looks of all that, but it may be the last best bet option

1989GTATransAm

iTrader: (3)

OK here is the answer from David.

"1989GTA,

Each termination box needs to be 8-10 times the volume of one cylinder - for each bank. also a 2 inch tube joining the two boxes is prefered..
DV"


This really puts crimp in my plans. I will have to give it another work over.

skinny z

Fabrication aside I think it's cool that you got a response from David Vizard.
Now considering the fab work, it's not getting any easier is it? In my case that's a 700+ cubic inch enclosure. That's a 4" pipe 60" long!
I showed my builder the terminator box that Vizard built for his friends vette and building it is not a problem. Stainless or mild steel he asked? There's just no place to put it. Once my car is in the air I may think differently but it's not looking good.

1989GTATransAm

iTrader: (3)

"There's just no place to put it"

Yep that looks to be the problem. I was thinking two pipes could feed into one 355 cubed resonator box for my application. That looked like it might be doable. Having two separate 355 cubed resonator boxes per David's reply is most likely going to be too much.

I agree that fabricating something is not the problem. It is the room.

Yes it was nice of David to respond and so quickly. I must have ask him just at the right time.

Orr89RocZ

iTrader: (20)

yeah well that is dissappointing. I can still do it tho since i plan to run true duals anyway.

And what do you think the deal is with the crossover 2inch tube? If i already plan to run a x pipe or h pipe, why would the boxes need a cross over tube as well?

For my collector length of 18 inch, there is NO way to run a tube connecting the boxes without serious clearance issues.

I'm starting to think collectors and cutouts are the way out of this mess Atleast if i try that first, and see how much power i'm giving up running a muffled exhaust over the straight tuned headers, then i can go back and make boxes to work since i will know how much power i can expect to gain.

if its only 10hp then i may not do it since i dont feel 10hp is justifiable for my build. But if its alot of low end power and torque all over the curve, then yes i will do it.

skinny z

In case all of you haven't read this article, here's what all the fuss is about.

http://www.superchevy.com/technical/...exh/index.html

Kind of makes me think back to my college days and the 68 Chevelle I was trying to make fast. Lots of room under that car!

skinny z

With respect to running tuned length collectors with cut outs, personally I think thats the simplest way to go providing you don't mind getting to the track and spending an hour getting the car prepped. Then there's the tuning to take advantage of the open headers. I would say that there's no substitute for the open headers, you just don't have that extra hp on tap for your Sunday drive..(unless you ARE David Vizard and have tuning capabilities coming out your ***). The real benefit of the resonator box is having that power available all the time. I'm pretty sure it would be worth more than 10 hp too.

Rayzor32

iTrader: (1)

yeah one 3" would definetly being choking it, a 383 needs DUAL exhaust. Dual 3" pipes would be killer, and dump before the axel and youll have even more flow.

Orr89RocZ

iTrader: (20)

this would be the easiest/quickest thing for me to do at this point to see how much power over the full length muffled exhaust i will gain when switching to open headers.

if i do gain alot, then hells yeah, i'll look into refabbing the exhaust to allow a resonator box. I think it can be done, but the BEST way will MORE than likely be a 4 inch pipe but i dont understand how that piece of pipe will act the same as a box of the same volume.

I understood it to be large crossectional AREA, not volume and a 3inch to 4inch doesnt seem to me a large section of area.

However a 36 inch length of 4inch pipe, radius being 2inch, i would have a volume of exactly 452 cubic inches, which is great for my 383 for each bank. thats about 9.5 times the volume of my cylinder.

i know for a fact i can fit 4inch pipe under there and 3 ft long sections. If it will act like a resonator, then by all means i will use it.

However the only down side is the cross over balance section. i wanted a xpipe and i dont think 3ft of pipe will alow that x pipe. H pipe would be the only option but it have to be custom.

Could i install a single 2.25 or 2.5 inch pipe between the two 4inch resonators to act like the balance tube? I think it would still act like the resonator and as David Vizard has said, he prefers a 2inch pipe connecting them.

that may be a way to do this

1989GTATransAm

iTrader: (3)

Hehehe. I see we are still at it. Looking at what Vizard did as shown in the picture for the Corvette in post 62 it looks like the termination boxes are long and skinney. So Jason I think your idea will still work.

As for me the only it would work is with the attached sketch I did. I would have to use 3" square tubing as shown in the sketch. I could bore a 2" hole in there somewhere. Maybe a little larger on the square tubing but not much.


Edit: One bank of cylinders would be tuned for best all around and the other bank would be tuned for best torque. Only way it will fit.

Here is the sketch.

Orr89RocZ

iTrader: (20)

Unfortunately your right on that, using stock style y pipe, you will not beable to make equal collector lengths using resonators.

But i dont like the idea of one bank being tuned differently than another. Seems like that could induce split blm issues and there is no way to tune that since we have no way of controlling each bank of injectors, its a batch fire system so your stuck with one fuel spray pattern.

your best bet is a pair of cutouts it seems, or a custom y pipe still using cats. I just dont see the room tho.

5678TA

i'll cut the BS, and add this.. my 2.5" true duals are not enough for my 385.. i have gained 2mph in the 1/4 with open headers.. thats about 20rwhp.. i'll be going to a true 3" dual with an x-pipe when funds allow.. for you, a mufflex 4" single would probably work pretty good or true dual 3"..

skinny z

5678TA
That's the whole point of this exercise. You demonstrate how open headers make more power as evidenced by your 2mph gain in the quarter.
Question: Did you use a different tune after you opened the headers? How long are your collectors?
We're trying to build a fully mufflered exhaust that will allow the engine to react like it's running with open headers.
Back in the day, with my 68 Chevelle there was a lot of room to build collector extentions and stick an open case style muffler on the end of the collector and then dump from there. There you have it. The collector exits into the muffler which, because of it's design, allow the engine to breathe like the headers were open. Not so easy to do on a lowered car.
Keep in mind for a drag race car like yours (11's n/a sweet!) there are probably huge gains to be seen from a properly tuned header secondary. Maybe even get you the fastest n/a car in Maui.
FYI: 2.5" exhaust pipe flows about 560cfm (standard pressure). If you make close to 450hp you need a total flow capability of nearly 1000cfm so your dual 2.5" is just large enough provided you have mufflers that flow the equivalent amount of air (and not a whole lot of bends in the tailpipe if you have any).

Orr89RocZ

iTrader: (20)

Yep i already know true dual 2.5 or single 3 isnt enough for my setup. So i'm thinking 3 inch duals. But the question remains can we build a zero loss muffled exhaust system? If i run open headers with proper collector length, i should gain no more power over my muffled exhaust system. thats the idea

skinny z

Orr89RocZ
The answer is Yes we can build a zero muffled system ( ala Vizard) however it looks like a lot of work on our cars.
Open headers here I come.
It would just be cool to roll into the track and blast 11 seconds with a fully streetable setup. ( or 12's with my combo). I just feel a little silly having to run open headers and only squeezing out an 12.75.

1989GTATransAm

iTrader: (3)

I wonder how much the tune will change going from a muffler system to open collectors. Maybe you will need two eproms for best results?

Orr89RocZ

iTrader: (20)

the tune wont change too much, just abit of minor timing adjustments and possibly alittle WOT PE fuel changes to get it perfect. Since i dont mind swapping out chips and can do so pretty quickly, i may end up doing this if i dont do the resonator things

I'm pretty much set on the 4inch by 36inch long pipe resonator idea. I think if that qualifies as a resonator since it has the volume i need, then its the best bet for my true dual system. it should fit ok and i should beable to meet my collector length goals. Plus its cheaper than fabbing up a box.

I really wanted to build a conventional system with cutouts at the right length to dyno test both of those systems to see the number difference. AFter i see how much power difference the proper collector length open headers make, then i will fab the 4inch resonators at that distance and redyno to see the effects to prove/disprove it works. Just gonna cost alittle more to do all this

5678TA

i see what you guys are gettin at.. and i did nothing after i took the exhaust off.. just upped the idle a tad since the back pressure loss made the idle drop.. my exhaust is not the best.. some places are bent to less than 2" dia.. oh btw, i basically have the fastest N/A street car on pumpgas.. i daily drive my car when i'm home.. only a cammed LS1 stands infront of me by 0.1 sec.. mainly because of the launch.. he gets me by .1 at the 60ft.. and i was running a hurt motor that wasnt tuned a whole lot.. got her rebuilt with more compression and a tad bit of pocket porting.. just waiting for school to end so i can get back home and race.. should be 11.3-11.4 as is.. getting a wideband A/FR guage so i'll get her tuned good and hopefully get 11.1-11.2.. i also got a few more tricks up my sleeve waiting for 10's..

skinny z

Carbed cars can expect several jet sizes up once the optimum collector length is determined (Pipe Max! I want it.) We've ( a race team I hang out with ) gone through 10 jet changes in an afternoon of tuning always trying to squeeze another couple of MPH out of the trap speeds. EFI cars should have an easier time of it.

Orr89RocZ

iTrader: (20)

yeah adjusting fuel in the tables of the ecm is ALOT quicker and easier to do than the carb i'm sure

What do you think i should do? SHould i just go ahead and run the 4inch pipe as my resonator and trust that it works, or should i build the conventional true dual and add cutouts with my 18inch collector length to see how much power it shows, then if it gains alot, i will add the 4inch resonator pipe and redyno to see the results?

its cheaper /easier to build the system the right way the first time... but having concrete hard evidence proving the science is always nice

skinny z

It's possible to tune the secondary length and move the torque peak around the rpm scale. Check Orr80RocZ's Pipe Max data to see what's going on. With proper tuning you can move the torque peak to coincide with your launch rpm. Better 60' times. Hello fastest n/a in Maui.

skinny z

Just remember to pay attention to the entry and exit into the box (thanks again 1989 GTA). 4" pipe has a few fabrication issues. How do you put dual 3" into a single 4" with the proper spec? Check this picture out.
That's for single resonator obviously. Dual resonators are a little easier except for the lack of room. Dual boxes would be 400 c.i each.( 4" x 32" for 400 c.i.) A single resonator out of 4" pipe would need to be almost 5' long. ( Like the picture for the Vette.)

1989GTATransAm

iTrader: (3)

That picture is similiar to what I had envisioned for my setup. However I thought a total of 355 cubic inches of resonator would do. With 710 cubic inches required I'm not sure I can do that. I just hate the posibility of leaving some easy power on the table. Gotta keep get ahead of that VincentZ28 guy.

Orr89RocZ: Looking at the other terminator boxes I have seen pictured I think your 4" round pipe scenario will work out just fine. I would go for it. I'm looking forward to seeing how your project turns out. It looks like you have all your ducks in a row. If you can get some 4" square tubing you might want to consider it. That way you can shorten up the terminator box.

Orr89RocZ

iTrader: (20)

I'm wanting to run 2 4" pipes about 3 feet long. A resonator for each bank. I'm not gonna join both tubes into one box i dont think

i dont wanna do a box since thats abit harder to fit and fabricate.

i want to run like this





I will look into running the oval/square stuff to gain better clearance. but that stuff is PRICEY

1989GTATransAm

iTrader: (3)

Looking good. The round tubing should work just fine. I only brought up the square tubing incase you need to shorten the 36" for some reason. You should have one heck of a combo.

skinny z

Orr89
Don't forget those collector lengths before the boxes are critical. You might want to experiment with open header extentions first and use your Pipe Max data before you commit to the drawing you posted.
Because of the experimenting involved and all the possible changes, that will probably be my approach for at least this season. It means running open headers at the track and doing some data logging however if there's 10 -20% available...

skinny z

Have you checked this stuff out?

http://www.drgas.com/store/home.php?cat=8

Might help in the fabrication.
Don't forget the collector length.
And you do need some kind of balance pipe if you don't run an x-pipe.

firebird896

These ideas look neat pick one, build it, and keep us posted

skinny z

Thinking open headers and collector tuning first. Go to the track and get some data.
Once the best configuration is figured out, build a resonator box system so there's open header like performance available all the time.

Orr89RocZ

iTrader: (20)

yeah i've checked Dr Gas, and probly will buy some things there.

You think thats the best approach? pipe max says 18-17 inch lengths for 6000 or 6200 rpm peak performance. I think my cam will peak by 6000 so i wanted to run 18inch lengths. It be easier to just build that system. maybe i should build that system and run a pair of cutouts in front of the resonators to see the difference between the two. if both are equal length collectors, then in theory i shouldnt lose any power when going from cutout to muffler exhaust.

I also wanted to do as you posted, with the inlet extended into the 4inch resonator about a inch or 2. Then have the rear exit smoothly with a cone reducer as i read you can do either bellmouth or tapered exit and both will work well.

obviously a tapered reducer would be easiest to work with since those are readily available

skinny z

There's nothing to stop you from running different lengths collectors either. For testing it would just be adding 6 inches one or the other to the open headers and try to support the Pipe Max data. Like changing jets or fuel maps.
Get that sorted and move on to the boxes.
An empty muffler case with dimensions 3.5" x 10" (oval) x 14" long measures 490 c.i. Think about that for space.

Orr89RocZ

iTrader: (20)

good deal man! Sounds like i should do that. exhaust pipe isnt THAT expensive especially if i plan to install all it myself if i can get a welder over here

thanks for all your help and everyone else's input on this subject. More minds working the better This has been a good thread for me, lots of learning here. Lets hope i can back up the designs with hardcore data

The 383 should be approaching completion in about 2-3 weeks depending on if all the parts i need come in on time

skinny z

I'm booked for the shop in about two weeks.
The LT headers are waiting on the shelf. I'll fab flanges for dropping the exhaust between the short collector extentions and the Magnaflow dual into plain old single 3" back Flowmaster. No cutouts. Just remove the 'y-pipe' and add extentions to the headers to figure out the tuning. Then there's no compromise that comes from running an open cutout with the rest of the exhaust still hooked up.
It would be nice to have the engine on the dyno to do all this stuff.

1989GTATransAm

iTrader: (3)

One thing about it. The exhaust will not be holding you back. A tuned and free flowing exhaust has to be worth 20-30 horsepower. That should put you well past 400rwhp and into the deep elevens at the track.

Drag Race 2000 says my car should run a 11.7 at the track and that is factored with a race weight of 3800 pounds. Heck you might even touch the high 10's with a good launch and weather.

skinny z

Want to try something cool?
Use Dyno 2000 and reverse engineer an engine. Take your best dyno tune and give it weaker and weaker exhaust and see what the results are. It explains why a lot of combos aren't as fast as they should be. Particularly when compared to magazine dyno engines. Ever check out header specs on those engines?

1989GTATransAm

iTrader: (3)

From Steve Mack's post: "For a reality check I have seen in the last two car craft magazines a 25% drive train loss on two well built motors. A big difference from fly wheel horsepower last build was 383 with a comp cams xe282 hydraulic roller 230/236 .510/.520 lift 215 TFS heads 750 barry grant speed demon carb. They had 326 hp 340tq to the wheels. So you have to pick your parts combo very carefully and have a good tune."

Not likely they were using the same exhaust from the motor dyno and the chasis dyno. Depending on how bad the exhaust was on the chasis dyno would account for the higher than usual loss of power.

skinny z: One of the members did that for me using EA Pro. That was the only way he could get the dyno graph to resemble what my real world one did. A restriction in the exhaust. I did have a bad catalytic converter so we shall see on the next dyno pull.