ExhaustPost your questions and suggestions about stock or aftermarket exhaust setups. Third Gen exhaust sound files and videos!
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Hehehe. Rest assured the tune will be next. However I will have to try the 18.5" collector deal and see how much horsepower might be there. If like you say if it is only 5 or 10 horsepower then I will leave it alone. However there might be more horsepower lurking there. I gots to find out. If there is I have in place a plan of attack on how to get it.
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indeed, i hope you get those results soon so i can decide if its necessary for me to pursue this further. I dont think its gonna be 5-10 hp tho, i'm thinkin more like 20
Vincent, one more thing. The next time you are over at Dyno Dons look at his dyno program and the difference in horsepower between a mufflered exhaust system and and open exhaust system. That is what I'm looking into. Remember nothing ventured nothing gained.
The only problem is that I'm not trying to run open exhaust or the cutouts. You, Don an I did the best thing already and that is modifing the header collectors from 2 1/2 to 2 3/4 and the 2 3/4 pipes through the 3in cats to 3in catback(for you 3 1/2 catback). Not much gain any other way. My gain was 20hp. How much more do you think you're gonna get?
If you gained 20hp with those mods, i'd be curious to see what open headers with proper collector length would gain over that. Hopefully Allen gets to discover this and feed us the information to help our builds
Allen wouldn't know! He made lots of changes all at once. So he doesn't really know how much of a change it will be. He change the exhaust at the same time while making an engine swap.
well i think he plans to dyno the current setup with no cats and the current exhaust system with better tuning. Then run straight headers with collectors at 18 inchs or so to see if it does anything different. should be a interesting comparison
[quote=VincentZ28;3718329]Is all of this really needed just to make 5-10 more hp in an everyday driven street car? $500 to $800 and the labor may be alot of time wasted. I was told along time ago to work with the stuff already on the car and get the most out of it. It's a lot cheaper!
I see your point however the terminator box set up we've been discussing may be more along the lines of 40 hp. That's only 10% (or less) on the vehicles we're talking about. There may be a higher percentage available. We'll see when Allen gets his dyno results with collector extentions installed.
40 hp is worth a lot of fabricating if it can be accomplished.
Last edited by skinny z; 04-15-2008 at 07:26 AM.
Reason: Automerged Doublepost
indeed, i hope you get those results soon so i can decide if its necessary for me to pursue this further. I dont think its gonna be 5-10 hp tho, i'm thinkin more like 20
Even a measly 10% is 40 hp!
I understand there's more. Mind you , you have to start with a poorly performing exhaust in the first place.
Like Vincent says, the've already done quite a bit of modifying in this area.
[quote=VincentZ28;3718514]The only problem is that I'm not trying to run open exhaust or the cutouts.
I don't think they are either . The plan is to determine proper collector length first and then build the resonators from there.
Or am I missing the point boys? Allen? Orr?
thats the point indeed. to simulate a open header exhaust with a full mufflered system. Its called a zero loss mufflered exhaust system. Find the proper open header length for best hp, and then build the rest of the exhaust to make the motor act like its still in open header mode
thats the point indeed. to simulate a open header exhaust with a full mufflered system. Its called a zero loss mufflered exhaust system. Find the proper open header length for best hp, and then build the rest of the exhaust to make the motor act like its still in open header mode
You guys were talking about lots of time and money for only a 10-15 horse gain. You're absolutely right..."most" people won't spend the time or effort to even try.
Skinny z and others who already have an existing exhaust to optimize, by all means...DO SO! And to you I really hope the wave term. boxes can work because it really is an excellent idea and I envy your enthusiasm.
To those starting with a clean sheet of paper and are planning a complete new exhaust, I urge you to at least try the recommended lengths/diameters...it will not be a wasted effort. I will say nothing more here on the subject.
EXCEPT:
They say knowledge is power...if it's only 10 horses, then it's 10 horses more than "most"... but you're forgetting about torque! (which is what really matters).
Some folks have seen over 60 ft/lbs. of additional torque occuring before peak power (with all areas optimised). If you're upshifting slightly above max power, your rpm's should fall right into the max torque "niche" and the car will recover from the shift better and accellerate quicker with that extra torque!
Some folks have seen over 60 ft/lbs. of additional torque occuring before peak power (with all areas optimised). If you're upshifting slightly above max power, your rpm's should fall right into the max torque "niche" and the car will recover from the shift better and accellerate quicker with that extra torque!
Yep I could not have said it better myself. The above seven replies are entirely correct. It is quite posible that only ten peak horsepower would be obtained but as stated the increased torque output in the lower rpms and under the curve might be considerable and that alone would make it well worthwhile. We will not know unless we try and that is the whole point of this exercise.
well i'll take torque if i can get it too i got a 383 so i should have plenty of torque reguardless... the stock L98 with bolt ons was enough torque for me.
But yes, i'm doing a from scratch build so i cant wait to see how it turns out.
I want to get it done asap so i can go to Pittspeed Dyno day again end of may. I probly will have it on a dyno before that tho
I want to get it done asap so i can go to Pittspeed Dyno day again end of may. I probly will have it on a dyno before that tho
I'll be passing by Pittsburgh (on the turnpike) 24th of May and staying in Virginia for a week. Going golfing and possibly purchasing a 84 Camaro coupe rolling shell I found on Craigslist.
It'd be cool to see your machine on the dyno.
That's wild.
I'm supposed to take my car as part of group. If I can pull it off logistically, (because of our scheduled arrival time in Virginia) it'd be a blast to watch the session. Provided you don't mind.
I would love to be at your dyno session but to much distance.
Anyways picked up the 2 3/4" L bends for my temporary collector mod today. Dyno Don will order the clamps for me and make them up to the 18.5" length.
I don't expect to get on the dyno for that test until some time in June. I will be on the dyno for my current combination in May. Got to get ready for the Los Angeles F-Body invasion drag race on May 26. There will be mostly 4th gens but I think our club will hold its own and surprise some of them. Maybe even embarass a few. The lowly TPI strikes again.
Go get 'em man! Love to see some thirdgens holding their own against some lsx cars. I got my hands full this year with MANY 4th gens, from mild cammed only cars to full blown 408's with heads/cam. This 383 better get it done
still waiting on my headers to come in and few other little motor parts so i can start to assemble it. gonna wire up the ignition box this weekend and if my parts come in by friday, i should have most of the engine done by sunday
Then i can start looking at the headers and how they will dump below the car. That will help me design the exhaust system
"Do you think you will have an opportunity to experiment with various lengths? Maybe open headers with no collector extension vs the 18.5" piece."
The chasis dyno's in my area are fixed in the floor. If there was one of the elevated type then maybe. The logistics are going to be bad enough because I don't want to drive over to the dyno shop with open exhaust. We are looking into putting the car on a trailer and taking it over to the dyno. The dyno shop does have lifts but that gets more involved and time is money.
Regarding the 4th gens. I have had good luck with them out at California Raceway. I have raced four over the years and won them all. Even beat a SC Mustang Cobra. The Cobra guy was so confident he had his girl friend ride with him. Probably cost him the race.
However I think at this meet my winning streak will come to a close. I know there are some pretty nasty 4th gens out there and I'm sure I'll line up against a few.
Last edited by 1989GTATransAm; 04-17-2008 at 04:18 PM.
To add to an already interesting thread is this article that I'm sure a lot of you have already read. However it is worth refreshing our memories. For what it is worth the exhaust section applies to this thread.
Edit: I'm sure they refering to long tube headers. By the way Joe Sherman posted the same results regarding headers. He said there was not 5 horsepower difference between them when he tested for the Engine Masters. Joe was refering to 1 3/4" headers.
Last edited by 1989GTATransAm; 04-17-2008 at 04:59 PM.
Yep. Hehehehe. Anyways I raced another SC Cobra and he beat me. He ran something in the very low 12's.
Oops, I think the thread is getting off subject and my fault.
What needs to be discussed is what is the best exhaust system for our cars.
1. What is the best system for long tube headers using mufflers?
2. What is the best shorty/mid length system for our cars using mufflers?
A lot of it depends on the type of muffler used. It's position in the system would change depending on the tuned length desired. You quoted Joe Sherman earlier. He was also in the books saying that he would use a glass pack style muffler and calculate his tuned collector length with the muffler included. Dumps would be right after the muffler. It would be easy to get a 36" inch secondary with that setup but where do you put it?
Regarding the short vs long tube header. I suspect there wouldn't have to be much difference in the overall design other than considering how the primary length may affect the secondary.
"Regarding the short vs long tube header. I suspect there wouldn't have to be much difference in the overall design other than considering how the primary length may affect the secondary."
Exactly what I'm looking into. Trying to make the best shorty/midtube header and collector. From what I have been reading the right "tuned" collector may be the bigger horsepower gainer of the two versus the header.
The way things have been going lately nothing I have done has got me past the 350rwhp mark. I'm right where I was one year ago. Maybe the next dyno tune will let me creep by somewhat.
The way things have been going lately nothing I have done has got me past the 350rwhp mark. I'm right where I was one year ago. Maybe the next dyno tune will let me creep by somewhat.
Not to jack Orr's thread but what's your best time at the track?
The combo in your sig looks very much like mine although I suspect your making quite a bit more power.
i'm trying to decide what type of muffler i want to use. My options are somewhat narrowed down to dynomax Ultraflo rounds or Powerstick chambered tubes again. Since i already got one chambered tube all i need to do is order another
but i'm considering selling my whole catback system to see what i can get for it to help offset the cost of the custom build. I'd hate to chop up the catback to use as pipe for my setup since its a nice setup but theres alot of good stainless 3inch pipe there
Anyway the powersticks give a nice GMMG type system sound and i loved it on my L98. However it was loud and i fear with more motor its gonna be alot louder..almost unstreetable so i think the Ultraflos will tone that down yet flow more than enough for my 383
I'm off to Disneyland today so I wont be posting. I would like to look into the muffler situation for Orr as that is all important. The times are in my Sig as I will put it on for this post. I was lowering the air pressure in my tires and the times were getting quicker. Need to do more of that. I feel 12.4's are available with the present combination.
__________________ Best et of 12.12 and best mph of 111.27 mph. Motor specs as follows: 355ci, Dart Pro One 200cc heads, 10.72:1 compression, 8.5:1 dynamic compression ratio, TPI with highly modified 1st style SLP runners, moded GM plenum and First Injection TPI intake manifold, Mike Jones 228/228 cam, Yank SS3600 converter, Dyno Don 1 3/4" shorty headers with excellent Dyno Don custom exhaust, custom cold air intake, AS&M monoblade throttle body. Race weight 3760 with driver. Meziere electric water pump. Mufflex 3.5" exhaust catback. Magnaflow 3.5" muffler#12909. Kevin91Z Tune. 4L60E installed.
Standard correction/unlocked 380RWHP, 371 RWTQ. SAE numbers are 370RWHP, 361RWTQ. Switched to MAP. At the motor that is 462HP SAE.
A 370 cubic inch motor based on the Dart SHP block is under construction. Using AFR 195cc Comp Heads.
but i'm considering selling my whole catback system to see what i can get for it to help offset the cost of the custom build. I'd hate to chop up the catback to use as pipe for my setup since its a nice setup but theres alot of good stainless 3inch pipe there
Cost indeed.
I just picked up 4 stainless steel U-J bends by Vibrant at 75 bucks each (US/CDN) and the merge pipe for another 35.
My fabricator is into me for about 1500 for some electrical work I did for him so I hope he charges me less than that. I'll keep the 3" inch cat back for daily driving and as a cost savings for now. Hedman LT headers I've had on the shelf for a coup[le of years.
And shocks..
struts..
steering linkage (again)
etc..
----------
Quote:
Originally Posted by 1989GTATransAm
I'm off to Disneyland today so I wont be posting. I would like to look into the muffler situation for Orr as that is all important. The times are in my Sig as I will put it on for this post. I was lowering the air pressure in my tires and the times were getting quicker. Need to do more of that. I feel 12.4's are available with the present combination.
Definitly more motor than I've got. I'm hoping to break into the 12's and believe my new exhaust will make a huge difference considering what I have now.
Enjoy Disneyland!
Last edited by skinny z; 04-18-2008 at 11:12 AM.
Reason: Automerged Doublepost
headers arrived this week and i have some hedman xtension s bends to play with. I havent reallly gotten under the car yet, but its gonna be hard to get 17-18 inch collectors i can do it but it will requre some good fabrication and possibly cutting subframe for max clearance. I wont have any as it sits...car is too low even without the engine in it!!
jacked the car up and looked under there. I got a way to route the pipes under/around the spohn crossmember but its not looking like the best clearance. I may have to sacrifice clearance tho or else cut those subframes which is what i want to do. I dont know how to weld and was planning on gettin a welder to learn. We'll see what happens. The motor is just about done and ready to drop in
EDIT: i noticed that link. DV says shape doesnt matter as long as there is a abrubt change in cross section.... I am assuming that is a area change? but he states that the volume is most important. So is a 3inch to 4inch pipe an abrubt cross section change?
I think as long as the collector pipe sticks into the 4" pipe and inch or two it should be allright. Looking at David's example on the Corvette one he built I don't see it being much different. From the picture you cannot see the depth of the termination box. I doubt it is very deep or much different than the width. There is only so much room.
thats a good point...it does look somewhat like a square 4inch 'tube' which is similar to 4inch pipe i'm sure.
Still not 100% sure what i may end up doing. I want to do a makeshift exhaust to get this thing running and tuned... then i can focus on proper system when i have more time and money to do it right. this stuff isnt real easy on thirdgens
Like we had discussed before, 3" collector into a 4" resonator pipe of sufficient volume will produce the desired result. Don't forget the importance of what follows the terminator boxes. You have to have mufflers with enough cfm capability to handle your expected hp.
Did you catch the post from the guy (in go fast news) who switched from glass packs to an open case style muffler? It shows how you can tune the collector length to include a muffler of the appropriate spec. Or ruin it. I've seen dual glass packs installs posted in the exhaust forum. It would be interesting to see some dyno/track results. It;s possible they've nailed the collector length without even trying!
i want to run dynomax ultraflo round's. i want to make the true duals using 4inch resonators about 36 inchs long. then the h pipe and over the axle and out using dynomax ultraflows. Not sure yet tho i still may go chambered tubes I loved the sound of the GMMG on cammed cars. Should still flow enough
Question on the 4inch resonators. Does it have to be perfectly straight? i wouldnt think so but can i have a slight bend to help point the pipe in the right directions towards the rear of the car to help with pipe routing?
Question on the 4inch resonators. Does it have to be perfectly straight? i wouldnt think so but can i have a slight bend to help point the pipe in the right directions towards the rear of the car to help with pipe routing?
It's still just a big chamber although I'd think that you wouldn't want to put 30* into it. We are dealing with pressure waves and bouncing them off corners and bends would undoubtedly change the way they behave.
Sounds like a good question for the likes of DV.
I have a question. What do you suppose the length of this exhaust would be if those mufflers behaved as an extention of the collector? Provided that the pipe is the same from beginning to end do you think that it might add up to one of the Pipe Max 2nd harmonics. ( 72" )?
yes, i took measurements alittle while back and that system lokos to be between 72-75 inches depending on how long the turn outs are.
thats a good picture of what i may end up doing for now.... just to get a exhaust on the car to get it running. Then i may go redo the whole setup to get it to how i want it. That setup is quick simple and cheap
There is a certain spec muffler, like a glass pack ( or chambered tubes? ) that reacts as an extention of the muffler like we've discussed. If the clearence is there and you don't mind how loud it would be you could skip the termintor box idea and tune to the 2nd harmonic don't you think?
What do you suppose the volume of this resonator box is? It would need to 760 + c.i. for your application. If it's a 7 x 5 oval, 24 inches long then it's pretty close. Probably no room though.
that is hard to estimate pic maybe looks like a 7-8inch by 4-5 inch thick by 15-16 inch box. Thats anywhere from 420-640 inches
I think i could very well fit a 8x5x20 or 9x4x20 ish box, angled diagonally by the trans tunnel, tuck it up nicely out of the way... i'd have to get under the car to verify, but i dont think i could make it 17-18 inches from my headers SO that probly wont work
It comes down to 4inch pipe resonators, twin boxes, or 72 inches for the other harmonic
I do like the long exhaust idea since it probly will be easiest/cheapest and work good still. Loud tho but idk how loud ultraflo rounds will be. I like the powersticks but they are abit more pricey i think and louder. I cant be too loud with this thing else it will be a race car. Hell i am probly gonna have to get a collector plate just to remain somewhat legal.
Tuning at the longer 72inch length.... Would that be as effective as the 17-18inch length? Is that the 2nd harmonic or 3rd/4th? I thought i read 3rd is best to tune for? If all goes well and i can dyno it mid may with just 18in open collectors, then i can quick fab the 72 inch with muffler and dyno again end of may. Eh, we'll see
However I will have to try the 18.5" collector deal and see how much horsepower might be there. If like you say if it is only 5 or 10 horsepower then I will leave it alone. However there might be more horsepower lurking there. I gots to find out. 
If there is I have in place a plan of attack on how to get it. 
you know why.. 
so i think the Ultraflos will tone that down yet flow more than enough for my 383 
