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I have been doing a bunch of research over the past few months, and figured I would ask the forum for their informed opinions and technical advice before I make any decisions on what to purchase. I've read a bunch of the sticky-threads here on the exhaust forum, and followed along with other people's bigger builds, but I am sure I missed some key points, so that is why I am making this thread.
For the brief rundown, it is a well built 406 small block chevy that made 531 horsepower and 513 foot pounds of torque on the engine dyno. I am also spraying nitrous to it, currently a 150 shot, and probably at most it would be a 200 shot. Teh heads are Dart Pro1 215 head with a 1.600 + .100 exhaust valve. In fact, the engine build sheet AND camshaft card can be found in post #1 of the thread I linked just above this paragraph. The transmission was built to the max by Dana at Probuilt automatics, and a 3,400 rpm 9.5" edge racing converter. IT has a Moser 12 bolt with 33 spline and 3.9 gears. This car is a street car first and foremost, but I run it often on the dragstrip, do several autocross events per year, and go to many car shows.
One of the drawbacks of the car has been the exhaust system. I have had the DynoDon's headers on the car for about 12 years, with my 305 tpi and when I ran nitrous on it too. It Has the DynoDon's y-pipe, no cat, a 3" electric cut-out, and a 3" hooker cat-back with the aerochamber muffler and dual outlet tips. Not having an unlimited budget to afford a set of Lemons or Ed Quay headers, my choices are limited. having no luck finding a pair of pre-built 1 7/8" long tubes, my research went to 1 3/4" long tubes. I know that hooker super comps are well used for 3rd gen sbc setups, but they do hang low under the car. Same goes for Dougs headers too. Lots of people run the "off brand" ebay long tubes, and from what I have read, they do not typically hang as low. They are stainless, sometimes with an adequate sized flange, and most come with some type of merge/y-pipe. So far these are my best bet, but I am open to all reasonable suggestions.
I am fairly confident that I do NOT have the real-estate under the car to do a true dual exhaust, and I really also don't have the desire to make that work just to have a "dual system". Can not do dumps or side-exit either, because this is a street car. A big diameter single exhaust is my most likely choice. Lots of people with considerable horsepower run a 4" single tube mufflex with a muffler and I think that could be a realistic option. The company mufflex is here in NJ and only about 1.5 hours away so I could try to deal with them directly and save on shipping costs. I would also run an electronic exhaust cut-out, and I have had good luck with DMH cut-outs. The ebay long tubes and the mufflex style systems do not meet-up, so I would have to fabricate my own y-pipe and mid-pipe, which I will simply buy some sections of pipe, some bends, and MIG/TIG weld them up here at my house. I also want to try to use some type of V-band clamps or band-clamps. Those junky universal horse-shoe clamps are horrible for long term use, especially if I have to take the exhaust on and off frequently.
my budget for this whole exhaust project is in the $1,200 range.
So my questions are:
- are there other options I have not considered?
- rough thinking, will the 1 3/4" long tubes be adequate for my 700 hp range? (I will try to play around with pipemax calculator)
- longevity of these ebay headers?
- how well do these actually tuck in between those framerails that are near the transmission?
- I'll have to figure out positions for the O2sensor bungs, are these ebay stainless "collectors" good for me to easily weld onto?
- any oddball issues with spark plug access? research shows it isn't bad with non-angle plugs/heads like what I have.
- real-world clearance of the 4" mufflex system in the tight areas? like over the axle and panhard bar areas?
Re: Headers and exhaust options for 700 hp street car
I had never heard of that company actually, hanks for posting that up! The length of those primaries seems to be almost the same as my Dyno Don's headers. I've never thought the Dyno Dons were "shorties" but more of a Mid length header, and thats what these appear to be. Also these headers would eat up pretty much all of my budget, but I am glad to know that someone makes a 1 7/8", cool.
I also forgot to mention in my first post, that I would liek the headers either stainless or shiny-coated, so they look pretty nice, because I do take the overall appearance of the engine bay at a high level of importance. It would be preferable to have the headers arrive coated/stainless so I don't have to have them treated locally for extra money.
Re: Headers and exhaust options for 700 hp street car
It's worth making phone calls to places like Stainless Works and ARH because they may have done something in the past that's not in their catalog and can pull up the file and run it through the bender.
I'd focus on the older companies that have been making products since the 80s and 90s when SBC was more popular. They're the ones that maybe have something on file that isn't advertised anymore.
Re: Headers and exhaust options for 700 hp street car
Remember that Mufflex has a 4.5" single on file from the job they did for my hemi. I don't think it would fit a lowered car but maybe worth a phone call if that interests you.
Re: Headers and exhaust options for 700 hp street car
The problem you will have is the longtubes and the pipes going around the trans subframe and cross member depending what cross member you run
doesnt matter really if its dual or single exhaust, that section is about the lowest you will have.
hooker super comps fit mine well, werent super low imo, but i custom made a ypipe around my spohn cmember in 3” and ran a single 4”. 500 hp ish 383 with a 150 shot. Lowered street car it hit alot on the roads over bumps and stuff. Just nature of the beast.
mufflex y should be similar in clearance. But i would agree that setup would need atleast dual 3”. 3” collectors going into a single 4” if you want a single
only way to do true dual with clearance is shorty headers and run the pipes down stock location. Those ARH 1 7/8 be nice if they had a 3” collector and you custom make the Exhaust pipes
Re: Headers and exhaust options for 700 hp street car
Subscribed.
If you don't have PipeMax yet, I'll crack open my older version and see what the crystal ball says. Let me know.
At your NA levels, you're probably over the line with Holley's Racing Heart series for the SBC in a 3rd gen.
My understanding is that with those headers, you can also use their 2 x 2 1/2" dual setup designed for an LS swap.
I thought I had confirmation from toddoky but I can't find it at the moment.
Might I suggest you search his username here. He's contributed to quite a few threads.
Re: Headers and exhaust options for 700 hp street car
great stuff here fellas.
I will probably follow Qwk's suggestion and contact some of the old tride-and-true header companies to see what they offer. In general terms, my combination all pre-LS swap type stuff, so it is (or was) really commonplace to have a stout small block chevy engine in a 3rd gen. The biggest thing I am running into is price. Budget and timeline is critical this year as life has a new adventure coming for me this summertime and camaro activities will come to a slow crawl. So winter (upgrades) and spring (racing and car shows) is what I gotta focus on, and tight budget must be adhered to.
I placed a call to Mufflex today and spoke with Denny. He told me that he has sold MANY 4" systems to 4rd gen sbc customers and installed MANY on cars that run around here in new jersey. We chatted quite a bit and he did agree that the single 4" system is a great option. I did ask about any price break if I made the trip to the shop to pick it up, and he told me it is unlikely, but also mentioned that product prices are going to be going up very soon due to 'supply chain and material" costs, but he could lock me in with a fixed price if I call him in the upcoming weeks. I have not yet completely tossed out the dual exhaust idea (as mentioned above by skinny), but routing it under the car appears to be more tricky compared to a large 4" single. Maybe next time I speak to Denny, I will mention that 4.5" that my hemi had them build. Denny and I did discuss the engine setup, nitrous shot, drag/street/autocross/show nature of the car as well as what I might do for headers.
My memory always brings me back to your car's old setup Orr. the nitroused 383, and how mine has many similarities. Some other people on this board are right in that realm, so I kinda want to go with a gameplan that could follow what you all did; as opposed to getting creative and "trying something new and uncharted". I can do that on another segment of the car, but for a functional exhaust, I want to do what has proven to work if I can.
As for the the underside, in recent weeks of research, I have seen where some guys will cut out sections of the unibody's frame and weld in some plate instead. I am glad I saw this, because if this is structurally sound.. it opens up options for me. I have a S7W racecars subframe kit which has a bunch of extra tie-ins when compared to your typical 2-point SFCs. I also have a 6-point roll bar in the car, so the chassis is stiff. I am handy with a MIG and TIG welder so, If it is ok for me to chop/cut/weld a bit of metal out of the oem framerails to make pockets or "pass-throughs" I can then route some of the y-pipe sections "through" the frame instead of underneath it .. saving ground clearance. I think LB9GTA did this a number of years ago, cut out parts of the frame.
not sure what other fellas like 383backinblack, diggler, anesthes, and IROCZ1989 are currently doing for exhaust... but if I remember right, they all are high hp sbc setups. (edit, I sent them private messages in case they haev some advice to share) My buddy John (JohnnyIroc) has run the hooker super comps and whatnot and liked them, but I know they hang lower than the ebay long tubes. I remember following along with you guys here: https://www.thirdgen.org/forums/exha...e-exhaust.html
Kinda wondering if people with those ebay long tubes are "Ok" with the 2.65" collector diameter.. as I know 3" would be awesome, but in real-world experience.. would that 2.65" collector diameter be good for 500+ street hp, plus another 200 hp on track days?
SkinnyZ: no I do not have pipemax as a program, I searched around and tried to acquire it, but instead found myself just reading over the old tables/charts for engine,hp,pipe size. Those are helpful and have steered me to the current components I listed in my first post. I did a search for threads by that toddoky user and see that he does have a bunch of exhaust related posts. I will be reading through those tomorrow. good stuff
Last edited by IROCZman15; 12-29-2021 at 09:39 PM.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by IROCZman15
I also forgot to mention in my first post, that I would liek the headers either stainless or shiny-coated, so they look pretty nice,
My stainless headers give off a lot of heat in the engine bay. I have a friend with ceramic coated headers and it makes a lot of difference in underhood temps. Easiest to do when new.
I have long tube headers, stainless, and V-bands at headers and mid pipe. That's a $2400 exhaust my friend and it was even years ago. And I would expect that prices could go up dramatically in a few days in January. I think you're going to need to adjust your expectations.
Re: Headers and exhaust options for 700 hp street car
very true, and I am fully aware that I could spend $2000 on custom headers along with all the other exhaust goodies for a total of around $4k and have an AMAZING exhaust system.. but with a baby (our first) on the way in June, my remaining car budget for the winter upgrades is only about $2500. This will have to cover the entire exhaust project, new rear drag wheels with 28" tall drag radials, A-pillar gauge pod with gauges and secondary O2 sensor, probably building a enw crossmember, as well as sending some pulleys and parts for powdercoating/metal finishing.
If viable options are out there for functional performance parts, thats the route I will have to travel down instead of dropping big money on stuff like I was able to do for recent years. So, thats essentially why I made this thread.. in order to find out what my real-world options are sot hat I can make a proprly informed decision.
Re: Headers and exhaust options for 700 hp street car
I will raise one point that you may want to consider.
A single exhaust will also consist of a single muffler.
If you want to hit the target of a least 2 cfm of capacity (2.2 actually) per flywheel HP produced before the system starts to impede output , then you're looking for a muffler moves 1000 CFM (NA). And this is a given that whatever single pipe you choose isn't a restriction itself.
That generally means LOUD!
Two mufflers obviously require half that capacity.
And now que the guys that say they have this or that and their output is just fine.
My question to them is: How do you know what you're leaving on the table?
Answer probably is: They don't.
And I'm talking scientific testing. Not seat of the pants. Or this is how fast I am. Give me back to back tests if you're going to offer resistance to that proven fact.
Re: Headers and exhaust options for 700 hp street car
I am not a fan of shorty headers myself, they seem to give up to much performance from a long tube in my opinion.
When I ran my 406 (450/495 ftlbs on motor) with a 100 shot, I ran the Hooker Super Comp 2210s connected to a Mufflex Y pipe and a single to dual tailpipe and was quite happy with the performance and sound. Had tons of torque with the long tubes. With the Hookers, you have many material choices if you want to keep costs down, but my recommendation is always SS if you can afford them. I would rather spend for SS than the cost of ceramic coating, and you can always have them coated later for a freshen up. I was running a T56 so had no clearance issues with this Y pipe, bit I would call Mufflex to discuss fitment with your auto.
Hooker 2210s Custom starter support made from 1/2" SS tubing.
I am still running the Spintech muffler which is a heavy beast. It is a tight fit over the axle, but no issues with suspension and all support brackets are OEM quality so good and strong. I later replaced the Y pipe with a custom Y setup and added a 4" cut out in the rear seat hump. The rear connection is fit to the unmodified Mufflex muffler and tailpipe system. Skinny - Would have to work out the flow restriction point, but I do know opening the cutout was good for 10rwhp on the dyno.
Clearance has been fine, except for the larger speed bumps in parking lots, which are accomplished with a sideways crawl.
Re: Headers and exhaust options for 700 hp street car
i ran the hooker super comps on my gta and i thought they had reasonable ground clearance. worked well for me, and i wouldnt sweat the 1-3/4 primaries.
i ran the mufflex 4" exhaust on my 4th gen and liked it, but it was heavy. probably 2 exhausts worth of weight, as it was at least 16-14ga tubing designed for a semi. it had a flowmaster on it but sounded KILLER. random rattle here and there over the axle as it was tight there. no room around the driveshaft, and had to cut the thing a couple of times to work on parts of the car since the exhaust was so huge.
if i were tasked to do your exhaust, i think i would do super comp longtubes (or similar), maybe a pair of electric cutouts off each header, and then run a 3" nice sounding quiet catback of whatever flavor you prefer. at the track, open the cutouts and the performance should be there on the bottle, and with less weight than the 4" exhaust. close cutouts, and drive it back home in peace with no rattles or racket. besides with the cutouts you can make racket with the flip of a switch if you want.
Re: Headers and exhaust options for 700 hp street car
I'll give you some input. The primary are not important as the collector size. 3 inch collectors. I wouldnt worry about 3/4 to 7/8. 3/4 I can just about bolt it on. I dont even want to imagine 7/8.Stainless works is about the only manufacturer that makes 1 3/4 to 3 inch collector in stainless. Problem is when you go to aftermarket heads, the header is up higher and out making the collector hit and not fit. I had 2.5 collector ss works and had a fab guy cut them and reangle to fit a 3 inch. Then used oval 3 inch y pipe to a single 4 inch which is about all you need. Then a Spintech 364sc which is the 4 inch in muffler dual 3 out. They tuck in tight on a factory headed car real tight.
First photo is how tight they fit on stock thirdgen 2.5 collectors.( Not my car) Bottom photo is my 3 inch with v bands.
I never coated my stainless headers. Really not needed. Yes coated runs cooler. It's a personal call. Most dont recommend coating stainless steel. On those cheap Chinese ones. Its your call. I wouldnt run them. They were never an option when I bought mine. They are a copy of the SW ones. Flange is not the same. Plus others have reported having to dent primaries to fit. Idk I dont buy alot of cheap ebay parts if any. Here comes the rub. SW are exspensive. Then won't fit depending if your exhaust port is higher than stock or not. If they are they need to be modified, added cost. If you go supercomps best bet if getting the coated ones because being in NJ these will rust if plain steel. Your budget of $1200 will be hard to do. But if you sell the headers you have now it will help defer some costs. Coated supercomps are in the 1000 range and don't know if they would fit depending on how high your exhaust port is. I think from the y pipe back is easy. Mufflex 4 inch and either the sinister single or the spintech. I wouldn't run anything smaller or bigger then a 4inch midpipe. Its tight but fits. Needs a drop panhard bar.
BTW mine is all custom fabbed from collectors back. But mufflex fit simaler.
So here is where I give my personal recommendation. I have had the Doug's, SW, Dyno Dons,Edelbrock TES and OG SLPs. Not super comps. Dougs and supercomps may fit out of the box even if you have the raised exhaust port like I do. Question is do you? SW will not. Its too bad Dyno Dons didn't have a 3 inch outlet. Is it an option??I would probably start with the headers.. seeing you can sell what you have to recoup some costs. I wonder if you can mod the ones you have.You will not be able to do new headers,y pipe and cat back on $1200. At your power level though 3 inch is tiny. I can understand your frustration with all this.Its a minefield of questions and options. And they are all expensive. Let me know if this has helped you any.
Re: Headers and exhaust options for 700 hp street car
To add to the 3" cat back being small, I agree, yes it will probably kill some HP vs the 4". However, I believe Taner bosnali made around 700whp through a 3" slp 2otl exhaust on nitrous, and over 500whp n/a with a 396 lt1. Just tossing that out there.
Re: Headers and exhaust options for 700 hp street car
If he made 500 thru a 3” he would have been 550 or more in a 4” lol
on the 450-500 whp late model ls3/LT 5/6 gen Camaros, they pick up 20 whp Or more from dual 2.5 factory piping to dual 3”. Nitrous you can never be too big imo
if you can figure out how to route piping around the trans subframe, ovalize or cut the frame or just live withthe small clearance issue, you will be fine beyond that point for dual 3 or single 4
i will add i had new poly engine mount bushings with my hooker headers and seemed fine for clearance. I can see how soft stock mounts may sit a touch lower. Also afr 195 heads with slighly raise exhaust port. That helps some
Re: Headers and exhaust options for 700 hp street car
Originally Posted by DIGGLER
To add to the 3" cat back being small, I agree, yes it will probably kill some HP vs the 4". However, I believe Taner bosnali made around 700whp through a 3" slp 2otl exhaust on nitrous, and over 500whp n/a with a 396 lt1. Just tossing that out there.
This...^^^
Originally Posted by Orr89RocZ
If he made 500 thru a 3” he would have been 550 or more in a 4” lol
And that...^^^
This is what I was talking about.
Exhaust is king. Choke to any degree and you WILL leave performance on the table.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by HP52TA
Skinny - Would have to work out the flow restriction point, but I do know opening the cutout was good for 10rwhp on the dyno.
I had similar results with a cutout right at the bend before my single 3" ChokeMaster.
IIRC, it was good for 1-2 MPH and better than a tenth in the 1/8th.
That particular combination was always crippled by an undersized exhaust system.
Re: Headers and exhaust options for 700 hp street car
I think he has 2 choke points. Collector size and the midpipe back. Those shorties collectors and y pipe are 2.5 if I'm not mistaken. 3in collector, 3 inch y into 4 mid. I just don't think that will happen on $1200. Only way around that is to redo the shorty collector and fab up a y pipe. That would be the cheaper way out. That would eliminate buying new headers for now.
Re: Headers and exhaust options for 700 hp street car
Wow, you guys rock! Lots to unpack and digest here. Lots! which is a good thing!
I am in agreement with you guys on most things here and I have to find a way to pull this all off with the various constraints (budget, clearance, performance goals, etc). And I wish I could take everyone's advice and pull the trigger, but unfortunately I am going to have to pick and choose what will work for me, so please don't think that I would discount anyones advice, it is all much appreciated.
The big dollar headers are so appealing, but I just know that I wont be able to purchase a set of $800+ headers, its too far out of reach. A few months ago my buddy John was selling a set of 2210 super comps that had some road damage and needed to be refinished, so I am going to check in with him to see if they are available. It is very apparent to me (thanks to you guys) that I will be ok with a 1.75" diameter primary tube so that is a relief because the 1.875" diameter tube headers are also out of realistic price range for me.
As for header collectors, I am glad you guys have assured me that a 3" diameter header collector is the ONLY way to go. The ebay headers (link in post #1) have a 2.5"ish diameter collector..and the same size tubes leading into the mouth of the Y pipe which then turns to 3" exit y pipe. I was NOT planning to ever use any of that that 3" y pipe section, I had planned on building my own anyways to mate to the mufflex 4". So, my question here is.. is it possible that I could simply cut off that necked-down last few inches of the ebay long tube header collector, and just weld on a simple mounting flange in its place? if you look at these ebay headers (photo below, link above), on the exit side of them.. the collector definitely tapers down to finish at 2.5" in diameter. However, inches before that (like where the 02 bung is) it is certainly bigger diameter.. probably at least 3" diameter? It has to be.... if it is merging four 1.75" pipes together. So, keeping in mind that I was going to built my own y-pipe anyways, why can't i just hack off the last few inches of the ebay collector, weld a flange or v-band, and then build my y-pipe off of that. It would be true 3" on each side merging into a 4" Y, and then to a 4"s single mufflex. Thoughts? To me, it sounds similar to what IROCZ1989 did, and I could probably even use some oval tubing in there as well like he did....
Photo showing ebay header collector "necking down" to 2.5", and my thought would be to cut it off before it tapers down and weld on a flange, then start building the 3"to4" y pipe:
next time I call mufflex I will ask the various questions you guys have posed. He did warn me that the sytems are solidl built, which accounts for a bit of weight, but I understand that. I for sure do want an electric cut out, as I have ran one for the past 8 years and it has usually been 2/3rd of the way open during normal driving and full open while racing. I hardly ever fully closed it unless I was getting home from a car event late late at night and coming through the neighborhood. So, decibels are not a huge concern, but having the proper actual sound (pitch/tone) is definitely important. Since the e-cutout will probably be left halfway open, I will have to decide which muffler sound will take care of the other half of the sound. I would much a deep, choppy and ground pounding sound as compared to a smoothed, mellow or even sharp and raspy tone. Mufflex has a few options for the 4" system,and some of you guys have direct hands-on knowledge and experience with these mufflers. I also no longer see the need for exhaust tips protruding out of the car, and therefore do not even think I want a muffler that exits into two tail-pipes either. Single 4" in and 4" out, dumped right at the rear of the drivers side corner is totally fine. I do have a tubular founders upper panhard bar brace and adjustable tubular UMI panhard bar. I have prothane poly motor mounts and a rubber trans mount.
There are some really awesome ideas here, and even a bunch of helpful photos. Even stuff not related to this exhaust project is catching my eye. Way cool.
-and yes, I do plan on selling the DynoDons headers, DynoDons Y-pipe, the hooker muffler, exhaust tips, as well as the electric DMH 3" cut out to re-coop some of the cost, but I will wait until the new exhaust is fully complete.
Last edited by IROCZman15; 12-31-2021 at 09:18 AM.
Re: Headers and exhaust options for 700 hp street car
loved how the flowmaster sounded on my mufflex, and want to say i liked it alot more than a spintech i heard.
i used a dual 3 into 4 flowmaster y merge to build my y pipe, and ran a 3" tube to each header.
Re: Headers and exhaust options for 700 hp street car
My buddys 406 has been 9.1’s with 1 3/4 Header and a custom 4” no muffler. 512 whp all motor plus 275-300 spray lol his was in a 4th gen which is easier to route pipe imo but size wise it will work
Re: Headers and exhaust options for 700 hp street car
You can cut those necked down headers and put a flange. Thats exactly what I did on mine, but I put v bands. The first link says raised exhaust port location on the heads. Every other one says standard port location. A test fit will show you where it is.. I like the sound of the spintech 364 with duals out. I did hide away tips. But the one in one out straight through should be good too. Probably loud as hell. 😆 Only thing I wish I did was do cutouts. Test fit those headers and if they are simaler to the SW they will fit up tight and dump around the transmission pan area where the linkage is. If you can get a set of headers used that would be good as well. You have a fab guy?
Re: Headers and exhaust options for 700 hp street car
Diggler: someone else had used that flowmaster y pipe as a starting point also. I think that might be my best bet, unless I want to build the whole entire Y myself. I have been considering buying some pipe and a box of bends. Ok cool. I have also heard people say that the spintech is too raspy and harsh of a sound. Flowmaster or magnaflow are my top choices for mufflers at this point.
Orr: perfect. Glad again to hear that the 1 3/4" wont ever be a restriction. I wont ever go 9's or spray this much nitrous as your buddy to this car, so that leaves me knowing that I won't be undersizing the components. thanks
IROCZ1989: thats exactly that I had my fingers crossed for and was hoping I was thinking properly about cutting hte necked-down portion of the colelctors off. I would much prefer a v-band clamp instead of the bolt on triangle style flanges. My fab guy (the guy who did the awesome quality 6point roll bar) took his successfully growing business to vegas to build hot rods, race cars, and sand buggies.. so no I currently do not have a top-quality fab guy. However, I am kinda geared up for the challenge. I recently got an old miller tig welder and Linder mig welder and have been buzzing away a few hours per week, so I am thinking that I want to try my hand at the collectors, y-pipe, and some exhaust hanger brackets. also if I have to cut out part of the oem frame rail and plate-it, I can do that.
Skinny, good to know. Also, when I have the dyno dons headers off, I'll take a measurement too. Good stuff. Here is a photo of the heads just a few weeks ago when I had the engine out to fix that oil pump valve/spring and pan gasket. I am not sure if a keen eye can eyeball that they are not raised port heads, but this is all I have got until i measure. I do trust everyones input and the internet tech sheets, so If they are not raised port, than thats allllll good.
.
- My buddy John does have those super comps but a bunch of the primary tubes need repair. So, I am leaving that as option 2 for headers.....
- Option 1 is those cheap stainless ebay long tubes, and I'll cut the flange and make my own flange at the 3" part of the collector. These "ship" from NJ, so I might even order em on Monday.
link: https://www.ebay.com/itm/30361071372...2Cchnl%3Dmkcid
I'll also call mufflex and maybe see if I can go down to their shop at the end of the week and purchase a 4" system (and maybe some pipes and bends).
Re: Headers and exhaust options for 700 hp street car
For the simplicity and money savings of keeping your headers, I would for sure modify them with a 3" v-band, then run a dual 3" into a single 4". Pretty much what I did with my twin turbo setup, following factory routing and getting it tucked up as high as possible. I used a dual 3" to 4" merge collector, mufflex mid/over axle pipe, and put a v-band on the end of that, as well as the muffler, so I could quickly switch from a spintech muffler, to a single, straight through vibrant race muffler. I found that the spintech muffler is actually incredibly restrictive even NA in the 500 hp range. I anticipate the single setup to be good for 800-1000hp. It is a LOT of work however.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by GTA matt
... a single, straight through vibrant race muffler. I found that the spintech muffler is actually incredibly restrictive even NA in the 500 hp range. I anticipate the single setup to be good for 800-1000hp. It is a LOT of work however.
I can see that just about any single muffler is going to be an issue once you're north of 500 CHP. That straight through race muffler is about the only option I can think off.
How is it for volume though? As in driving on the street?
Keep in mind that this is coming from a guy who's willing to drive the 30 minutes to the track with open headers!
Re: Headers and exhaust options for 700 hp street car
Originally Posted by skinny z
I can see that just about any single muffler is going to be an issue once you're north of 500 CHP. That straight through race muffler is about the only option I can think off.
How is it for volume though? As in driving on the street?
Keep in mind that this is coming from a guy who's willing to drive the 30 minutes to the track with open headers!
The single vibrant is pretty loud out the back in an NA setup. Inside the car is pretty tame.
Re: Headers and exhaust options for 700 hp street car
Your 3-in single is really quiet compared to what you're about to get into. Anything you do to make the exhaust system naturally support a lot of horsepower is going to result in the exhaust system being very loud. My 3.5-in single has caused me hearing damage.
The way around that is large dual pipes with S-tube mufflers. Basically the exhaust system is so big that the restrictive mufflers aren't actually a restriction for your setup. But we don't have the real estate for that under our cars.
So that leads back to the cutouts. It pretty much always leads back to cut outs because we don't have the real estate for better things.
If you want duals then you could retrofit a 4th Gen dual exhaust into your third gen. At least the hard part of the bends over the axle will be done for you. Texas Speed, Kooks, Speed Engineering all have dual 3-in for the 4th gen. And they're all loud as heck... I mean super freaking loud.
The other way around the noise issue is 100 lb of sound dampening in the interior. You make the noise, but less of it gets to you.
The conversation always starts out with which exhaust system makes the most power and eventually ends with damn my car is too loud. You don't have a race car, you have a street car that makes a lot of power and you want to be able to enjoy driving it. Your ears can only take so much and that has to be considered.
Re: Headers and exhaust options for 700 hp street car
Did someone mention cutouts?
I really like the sound of the little 3" Flowmaster I have. But, at an arguably less than 300 CFM, the problem is obvious.
Now, at my power levels, which are not 500 HP, at least not historically, whatever restriction the exhaust imparts, output is still plenty abundant on the street. I can't keep the tires underneath as it is. Now, track days are a different story.
For me personally, I'm not terribly interested in installing an entirely new exhaust. Dual 3" though would more than enough. Even Holley's 2 1/2" setup, depending on the capacity of the mufflers, would probably fulfill 90%of my needs. But I'm just not interested. At least not at this juncture.
Did someone mention cutouts?
Re: Headers and exhaust options for 700 hp street car
And if you want to get really fancy you can design the cutouts so they are at the end of a Hiemholtz chamber which will make your exhaust extra quiet during normal use.
Re: Headers and exhaust options for 700 hp street car
Not sure of the volume level or the resonator but the most significant point of the cutout is to take advantage of the exhaust pulse tuning. CFM notwithstanding, it's that tuning that will improve the overall VE and that's where the HP comes from. This is provided you have the cam that supports it. It's all in the overlap.
Last edited by skinny z; 01-01-2022 at 01:07 PM.
Reason: speeling
Re: Headers and exhaust options for 700 hp street car
I can say one thing about track days and that's when I'm lined up beside someone running open headers, I can't hear my own car. I need to turn up the volume!
Re: Headers and exhaust options for 700 hp street car
One other idea that is being used more and more by the OEMs is a progressive bypass built into the muffler. I don't remember whether the Holley Sniper has PWM output to drive a progressive valve?
I suppose you could do the same thing with the bypass mounted anywhere as long as the bypass has a pwm controller.
Re: Headers and exhaust options for 700 hp street car
Great tech info here fellas, and also a thank you to GTA Matt for joining the discussion with his experience and advice.
- Hopefully later on this thread will help some other people who are researching exhaust options for higher-horsepower sbc 3rd gens.
I see you guys chatting about those new style "variable" mufflers. Coincidentally, Stan just made a video only 3 days ago where he installed one of those mufflers and at the same time, got rid of his dual 2.5" exhaust pipes in favor of exactly what we are talking about here... a 4" mufflex system. What a coincidence!
link to his youtube video:
I decided to order the $212 ebay stainless-works knockoff headers; placed the order on ebay today so maybe they will be here this week? I think i would have had too difficult a time repaiting my buddies used super-comps, and would still have to get them coated afterwards. So, I'll cut the ebay header's collectors and put v-bands on them. I'm hoping that this friday I can drive on down to mufflex and grab the 4" "cat-back"kit, but I will have to decide which muffler I want. I'm still at the age (37) where I like the car loud and rowdy, so a single 4"in and 4" out muffler that favors performance over quietness is most likely what I will go with. I do have almost all of the interior floorboards covered in RaamMatt which is a product knock-off of dynamat, so I am hopeful that it can keep my teeth from rattling out of my head. Even with my car's single 3" cutout open at the track, its drowned out by a drag car next to me with open headers...to the point where I sometimes have not even know if my car was even running or not!
As for cutouts, I am most certainly definitely doing that; it was always in my plan. I am going to wait until after I have the headers installed and start planning the collectors+ y-pipe stuff, because I want to see if I can somehow fit dual 3" electric cut outs. I already have a 3" DMH cutout (has been on the car for over a decade) so if I have space for dual cut outs, I will just buy another 3" dmh and wire them together. However, if I have no space underneath, I will sell the 3"cutout and buy a 4" cutout and figure out a good place to weld it in. Qwk, holley sniper does not have that capability. I would think that the dominator and holley hp would, but the sniper being the entry-level efi system, it was purposely left out as a feature.
Last edited by IROCZman15; 01-02-2022 at 08:52 PM.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by IROCZman15
So, decibels are not a huge concern, but having the proper actual sound (pitch/tone) is definitely important. Since the e-cutout will probably be left halfway open, I will have to decide which muffler sound will take care of the other half of the sound.
Oh, I'm not kidding, you won't need the cutouts for driving. The decibels are going to go way up with the 4" pipe. My car is louder than my friend's LS2 even with both his cutouts open on the 2.5" duals.
I really wish you could spend 30 minutes in my car. The first 10 minutes are awesome, the last 10 minutes you wish you had ear plugs. You step out of my car with dulled hearing and mild ache. One day I snapped the throttle in a parking lot and my right ear hurt after that. I've had hearing loss in that ear ever since.
Re: Headers and exhaust options for 700 hp street car
Be prepare that transmission (th700)shifter linkage is very close to collector,at my setup(maximizer ebay longtubes) there is no room to remove 2.5" reducer and replace it to round 3" collector.And what too small exhaust means to trap speed,at my case difference was from 113.3mph to 116.7mph (longtubes,2x2.5" y-pipe single3" pipe and dynomax ultraflow to longtubes +dual 3")
Ps. before duals car was nice quiet to drive,not anymore ...
Re: Headers and exhaust options for 700 hp street car
Originally Posted by z 28 jari
Be prepare that transmission (th700)shifter linkage is very close to collector,at my setup(maximizer ebay longtubes) there is no room to remove 2.5" reducer and replace it to round 3" collector.And what too small exhaust means to trap speed,at my case difference was from 113.3mph to 116.7mph (longtubes,2x2.5" y-pipe single3" pipe and dynomax ultraflow to longtubes +dual 3")
Ps. before duals car was nice quiet to drive,not anymore ...
There is room. My head exhaust ports are raised .375 from stock and poly mounts. You have to put them on a slight angle to work. I have the og SW. Its tight.
Re: Headers and exhaust options for 700 hp street car
Originally Posted by QwkTrip
Oh, I'm not kidding, you won't need the cutouts for driving. The decibels are going to go way up with the 4" pipe. My car is louder than my friend's LS2 even with both his cutouts open on the 2.5" duals.
I really wish you could spend 30 minutes in my car. The first 10 minutes are awesome, the last 10 minutes you wish you had ear plugs. You step out of my car with dulled hearing and mild ache. One day I snapped the throttle in a parking lot and my right ear hurt after that. I've had hearing loss in that ear ever since.
My 4 inch with the spintech 364 is really loud, thats an understatement.I agree cutouts might not even be needed. Saving fab work and room underneath.
Re: Headers and exhaust options for 700 hp street car
I'm not entirely certain that the point of having cutouts isn't being lost here. It has little to do with CFM although they will provide that in spades.
The point of the cutout is to provide the tuned collector length for the purposes of exhaust scavenging.
By placing the cutout at the calculated and appropriate distance from the end of the primaries, the reflected negative pressure pulse as it arrives at the exhaust valve is a benefit and produces a bump in the volumetric efficiency by drawing in the intake charge before the piston is descending down the bore ( or only just). Conversely, if you place them in an arbitrary location (for convenience or fitment), you can kill cylinder filling because the reflecting pressure wave arrives at the exhaust valve at precisely the wrong time. That's a recipe for reduced output.
Just saying. I've noticed a couple of comments that seem to me to be more about the flow than the real purpose.
Open header performance is the objective.
I can't help with the volume thing.
Last edited by skinny z; 01-03-2022 at 08:20 PM.
Reason: clarity
Re: Headers and exhaust options for 700 hp street car
Qwk: I've seen a good amount of photos of some fellas here with the Chinese stainless headers that the finish seems pretty good. I know that all Chinese stainless are not created equal (or good for that matter) but I am going to keep in mind about coating them, along with the section of collector/y-pipe I have to build. I have been chatting on the phone with a local metal coating shop, and they are going to be doing some coating on my two engine pullies and rear diff cover next week. He has a few options for high-heat coatings so when I drop off the pulleys I am going to explore his high-temp coatings and chat with him then. Also, I would freaking love to take a ride in your car, probably for more than 10 minutes haha. I do understand what you are saying regarding the noise. There is really no way for me estimate the volume level that this new exhaust will produce, so I am going to have to take it as it comes.
z28jari: good to know. I am aware that the fitment of headers varies from product to product and from car to car. I am simply hoping I have a situation that can be resolved by some fabrication and creativity. I have a mini-starter and plan to build new transmission lines out of copper Nickle to route them out of the way of the headers. The oem steel lines look like they will be problematic. I'll just go to autozone and buy a few feet of 5/16" copper Nickle tube and some inverted flare type fittings. As for the transmission stuff, that I will have to see once I get the headers bolted up. I can't make too many assumptions, but once I start bolting stuff in.. I will post plenty of photos/ideas up here. And regarding trap-speed, my NA runs do seem a mph or two mph lower thane expected, so I have always wondered if my dyno don's and 2.5"to3" dyno dons y-pipe were choking the engine a bit. Probably yes. When the track opens in the spring, I will see how I do NA and then also on the nitrous.
IROCZ1989: I have heard a bunch that the spintech is a loud setup. I am probably going to cross that muffler off the list... so flowmaster or magnaflow would be my choices. Never been a flowmaster fan ever, so probably magnaflow.
skinny: yep. I am hoping that if I do run the cutout(s), I am able to install them in the optimal place as to provide actual power savings, instead of just noise. To be determined.
Headers should be arriving on Thursday, so there is a good chance I can get them rough-installed this weekend. If I am able to go to mufflex on Friday, I will also try to get the 4" system installed as week. fingers crossed.
Food for thought, discussion welcome...
-skinny and I were emailing a bit because he was super helpful enough to run some of my engine specs through his PipeMAx programs. The data up top is pulled directly from my engine build sheet, cam card, and engine specs. Surprisingly the 1.75" setup is best for race only, and it also recommended a 1.675" primary for a street-strip application. Interesting!
(PM1 and PM2 are from the same tabulations just page'd down) race header
PM1: [/url]
PM2:
(PM3 and PM 4 are also of the same calculations, just scrolled down the page) street headers with mufflers
PM3:
Re: Headers and exhaust options for 700 hp street car
Originally Posted by IROCZman15
Food for thought, discussion welcome...
-skinny and I were emailing a bit because he was super helpful enough to run some of my engine specs through his PipeMAx programs. The data up top is pulled directly from my engine build sheet, cam card, and engine specs. Surprisingly the 1.75" setup is best for race only, and it also recommended a 1.675" primary for a street-strip application. Interesting!
(PM1 and PM2 are from the same tabulations just page'd down) race header
I've never used PipeMax - verify it, but I suspect that it's giving inside diameter of the pipe. Most 18 gauge 1.75" headers (advertised outside diameter) have an inside diameter of 1.65". 18 gauge 1.875" headers will have an inside diameter of 1.775".
I’ve been sizing exhaust systems around Vizard’s “Zero Loss” formula for many years without disappointment. He established (dyno testing – flywheel HP - straight pipes) that you need approximately 2.2 CFM of flow per HP at 20.3" to not see any reduction in power.
Actual published flow measurements in bold below were for a SINGLE straight pipe measured at 20.3” water. By all accounts (including my own track testing over the years), there appears to be about a 20% drop in flow using mandrel bends in a typical car exhaust system - flow and HP numbers for an exhaust system below are estimates.
2.25” Single Straight Pipe - 494 CFM = 225 HP
Single Exhaust System - 395 CFM = 180 HP (Duals 360 HP)
2.5” Single Straight Pipe - 610 CFM = 280 HP
Single Exhaust System - 490 CFM = 225 HP (Duals - 450 HP)
If you’re running headers and basically straight pipes to the mufflers with a short mandrel turndown (no tail-pipes), a dual 2.5” system would be good for power levels up to 500 HP.
3.0” Single Straight Pipe - 878 CFM = 400 HP
Single Exhaust System - 700 CFM = 320 HP (Duals - 640 HP)
If you’re running headers and basically straight pipes to the mufflers with a short mandrel turndown (no tail-pipes), a dual 3.0” system would be good for power levels up to 700 HP.
3.5” Single Straight Pipe - 1,196 CFM = 545 HP
Single Exhaust System - 950 CFM = 435 HP (Duals - 870 HP)
If you’re running headers and basically straight pipes to the mufflers with a short mandrel turndown (no tail-pipes), a dual 3.5” system would be good for power levels up to 950 HP.
4.0” Single Straight Pipe - 1,562 CFM = 710 HP
Single Exhaust System - 1,250 CFM = 570 HP (Duals - 1140 HP)
Once you know what pipe size you need for your power level, then you have to find a muffler. The mufflers below were also tested at 20.3” water. This test was published a long time ago, but most of the mufflers are still available. Take note, to not lose any power you will need a muffler that flows as much or more than the single exhaust system rating. It’s pretty easy to see why people advise against Flowmaster mufflers for performance applications - they are far from masters of flow. Also take note that if even if the muffler can flow more than the exhaust pipe utilized, the potential power level of the muffler is limited to the flow of the exhaust system's pipe diameter.
2.25” - Single Exhaust System - 395 CFM = 180 HP (Duals 360 HP)
Flowmaster 40 Series 42440 - 348 CFM
Edelbrock 5501 ------------------ 492 CFM
DynoMax Welded 17216 ------ 711 CFM - pipe limited to 494 CFM
2.5” - Single Exhaust System - 490 CFM = 225 HP (Duals - 450 HP)
Flowmaster 40 Series 42540 - 352 CFM
Hooker Aero Chamber ---------- 378 CFM
Borla Turbo ------------------------- 434 CFM
DynoMax Ultraflow Bullet ------- 596 CFM
Hooker Max Flow ----------------- 606 CFM
Borla 40600 ------------------------ 836 CFM - pipe limited to 610 CFM
DynoMax Welded 17218 ------- 1000 CFM - pipe limited to 610 CFM
DynoMax Ultra-Flo 17263 ------ 1133 CFM - pipe limited to 610 CFM
3.0” - Single Exhaust System - 700 CFM = 320 HP (Duals - 640 HP)
Flowmaster 40 Series 43040 -- 392 CFM
Edelbrock 5505 ------------------- 708 CFM
Borla 40575 ------------------------ 1100 CFM capability - pipe limited to 878 CFM
Borla 40450 ------------------------ 1400 CFM capability - pipe limited to 878 CFM
Ultra-Flo SS 17296 --------------- 2200 CFM capability - pipe limited to 878 CFM
DynoMax Welded 17220 -------- 2200 CFM capability - pipe limited to 878 CFM
3.5” - Single Exhaust System - 950 CFM = 435 HP (Duals - 870 HP)
Edelbrock Victor 5535 ------------ 562 CFM
Flowmaster 40 Series 435409 -- 576 CFM
Borla 40615 -------------------------- 854 CFM
DynoMax Ultra-Flo SS 17268 --- 2200 CFM - pipe limited to 1196 CFM
DynoMax Welded 17224 --------- 2200 CFM - pipe limited to 1196 CFM
4.0” - Single Exhaust System - 1,250 CFM = 570 HP (Duals – 1,140 HP)
Flowmaster (5” case) 54040-10 - 634 CFM
Edelbrock Victor 5537 ------------- 1400 CFM
Borla 40741 -------------------------- 1450 CFM
Before I sold my IROC I was planning on a full exhaust upgrade and was planning on running full dual 3" pipes by hook or crook. The single 4" looks to be a more viable option for these cars though. If I were you I'd still run the dual 3" pipes for as long as I could before the Y-pipe transition to the 4" pipe. There are some terrible transition Y-pipes out there - I prefer using the Flowmaster Scavenger Series Y-Pipes (below), but you'll probably want something in stainless and FM doesn't make the 3" to 4" Y in stainless.
I'd also look to fit the biggest cased straight-through design muffler that would fit. I ran a 17227 Welded UltraFlo 3" in and dual 2.5" out (4.5" x 9.75" x 20" case) and it was fairly quiet at cruise and didn't drone - much smaller pipes I know, but the case on that muffler is bigger than most and helped a lot compared to other mufflers I'd heard of the same sized pipes. I looked around a little and there's not a lot of choices out there. However, Borla makes a pricy 4" in/out XR1 with a 23" case - if it would fit, that's what I'd run on a single 4" system. I ran dual 3.5" Borla Sportsman mufflers on my daily driver back in the day and while relatively loud, they were MUCH quieter at idle and cruise than a buddy's car (both MCSS) running dual Flowbastards.
12-28-2021, 09:09 PM
The decibels are going to go way up with the 4" pipe. My car is louder than my friend's LS2 even with both his cutouts open on the 2.5" duals.
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