Exhaust Help: Not ya standard situation, please read and guide me on this

[87ChevyR10]

Ok, my situation is kinda crazy, on a non-related topic, im semi-homeless and have been so since the last day of sept so my chance to respond isnt like it was. I bought wifi at a pilot rest stop(when it wants to work) so i am good in that respect, so ill try to respond when i can. With that said...

I'm trying to get my 87 a1 before i get outta Savannah and make the long ride back home for good. Some of you may be familiar with me from my prior post desperately asking for help/guidance on the issue i was having prior. Well, the cat ended up getting clogged up too, so i cut it up outta there in prep for redoing the entire exhaust system over from top to bottom, including replacing the stock headers. I'm trying to go with 2.5 in pipes, not sure whats better, 2.25 or 2.5, but everyone i talk to tells me 2.5, so whatever is best for performance/sound/mileage help. Ive looked at some header back/manifold back options but im kind of lost. I honestly dont know whats best, which is why im here. I'm not tryna spend a 1000 dollars obviously with my situation, but being my situation is what it is and that the 87 is pretty much my home til i get outta savannah, i will spare no expense in making sure its taken care of. SO.... id like to find thru summit or simililar an exact fit setup for my r10 that includes the headers/mufflers and pipes, but its not likely as i keep running into 2.25 applications. This is what ive been looking at..... ill show you that ive attempted doing my research, i just need a more informed hand to guide me where i need to goI do have a pretty decent idea of what i want though.

I wanted to roll with these, assuming they'll work with my truck(87 r10, 305 5.0l)
http://www.jcwhitney.com/flowmaster-super-40-series-muffler/p3088950.jcwx?skuId=1240135&filterid=d50303y1987g702j1
youtubed these and loved the sound, ima straight pipe it and not replace the cat, so coupled with these and the right pipes, i believe it should make her growl pretty nicely, no?

As far as the whole thing goes, took a peek at these, but most or all of these options are 2.25in pipes... grrr
http://www.summitracing.com/parts/hok-16622hkr/overview/year/1987/make/chevrolet/model/r10

not sure the diff between the two below without studying them but i know i saved both links for a reason, but according to summit, both these will fit.
http://www.summitracing.com/parts/sum-cbjj202/overview/make/chevrolet/model/r10
http://www.summitracing.com/parts/sum-cbjj102/applications/make/chevrolet/model/r10/engine-size/5-0l-305

http://www.autopartswarehouse.com/sku/Chevrolet/R10/Heartthrob_Exhaust/Exhaust_System/1987/Custom_Deluxe/8_Cyl_5-dot-0L/HEA1004385.html?tlc=Engine+%26+Drivetrain

just a few of the options i had. now, i am not opposed to piecing together what i need outside of the options i posted. now, im not deadset on anything, but my heart is def set on the super 40s and the 2.5 pipes. the y/x pipes i know nothing bout, but people i speak with down here are telling me one or the other, so help there is def needed. i want some great headers that will really make a difference, but i dont want a set of headers thats not going to fit the use of my truck. Its an everyday driver, no strip/racing so i dont need anything along those lines. I had liked a set of flowtechs i seen but, after looking closer, it was geared for racing purposes. queue up the price is right wah wah wahhhhhhh sound.

ok, i hope this helps give you an idea of what im tryna do/looking for. ill try to get back on tonight, but, i imagine it'll take a few days for the regulars to weigh in.

[rich weyand]

Why are you set on 2.5" pipes?  A normally aspirated 350 can't fill up a set of 2.25" pipes below 5000 rpm, much less a 305.  You are costing yourself extra money and trouble for exactly zero benefit.

Now, if you were racing a 350, had reworked the engine for higher redline, put a blower on it, and were spending a lot of time running it in the 6000-7000 rpm range, that would be different.  Short of that, 2.25" pipes are fine.

Since you're set on it, let me do the calculations.  A 305 pumps no more than 305 cubic inches of volume every other crankshaft revolution.  The actual number will be less by some amount, called the volumetric efficiency, which does not go over 1 for normally aspirated engines.  That works out to 440 cubic feet per minute at 5000 rpm.  This link says dual 2.25" pipes will flow 800 cfm, and are suitable for applications up to 370 hp: http://www.exhaustvideos.com/faq/how-to-calculate-muffler-size-pipe-diameter/.

So the 2.5" pipes are extra expense, harder to find, and give zero benefit, because your flow rate is more limited by the carb, and ultimately is limited by the valve train, heads, cam, and cubic inched of the engine.

I have 2.25" duals on my 350, no problem.  I am also running the Flowmaster 40s (not Super 40s), and like those.  I had the pipes custom bent up and installed by a shop that knows what they are doing.  It was $480 for everything from the headers back, including the Flowmasters and the H-pipe.

If you want to spend a little extra money on something that will make a difference, have them put in the H-pipe.

[454Man]

Go 2.25. You won't need any more on a 305... Sure 2.5 pipes will sound better but it will be at the expense of any bottom end torque that 305 will make. I vote 2.25 and a chambered muffler and you'll like the sounds and performance. If money permits id also throw some sorry of cross over H or x pipe on it. Fwiw every thing I've thrown 2.5 pipes on under 350cid was a dog after. Kinda made me wish I stayed with the factory y to single pipe...

What's under the hood??? If you have to ask maybe we shouldn't race...

[Irish_Alley]

im with them 2.5" is too big. even 1.75" (dual) is good for 217hp

[87ChevyR10]

1st of all thank you for the replies. I finally caught a day off, so im at McDs with the sole intent of checking and responding. Per the replies, it makes sense to not run with 2.5", which is exactly why I came here, for insight, opinion and help cause im straight lost on the exhaust end.

Rich - dang, you done pulled out the calculator and did the math. Hard to argue with knowledge and provided fact. i guess im not all the way set after reading that. Its whats been referred to me by several folks, but info/fact that has been provided here makes more of an impact to me than random opinion thats been given on behalf of the 2.5" pipes, so with that said, 2.25 sounds good to me, i just want her to growl quite nicely!

So lemme lock the 2.25s in, ive got three things which im lost at now. Whats the diff in the x/y/h pipes? Is there a benefit of one over the other? I gotta sit and do my calculations again and set everything at 2.25s now, no biggie, whatever is best for the life of the motor, the performance and sound, thats what im after. i gotta run back over the options i linked, and perhaps decide to piece it all together instead of going with a kit. I just want everything to mesh, fit and not have to be returning stuff, cause i aint tryna be returning stuff cause its not an exact fit.

Anything on the suggestion tip for headers, say on the chance i DO piece it all together and dont go with the kit or has what i provided been aight options?

To everyone who has responded, thank you very much. Outside of my pops and the guy whos working on my truck as we go, i really have no one to lean on for advice/help. Yall fellas are coming thru again! I wouldvve been responded but pilot wifi is a POS. one day it works, one day it doesnt. Great purchase for 19.99! smh

[rich weyand]

On the X, Y, H pipes.  I went with an H pipe.  It seemed more appropriate for low-end torque, where the X pipe would be more appropriate for high-end horsepower.  It also fits really easily under the truck.  Just 2" pipe for the H-pipe is more than enough.  There's no real flow there.  I didn't look into the Y pipe.

So what does the H pipe do?  Well, if you look at the firing order, and substitute Left and Right for the cylinder numbers, you'll see the firing order is L-R-R-L-R-L-L-R-L-R-R-L....  So one out of four cylinder firings follows immediately on another on the same side.  This is to balance out vibrations.  What it means is that there is not a smooth flow in the exhaust, but a little over-pressure on the left, then the right, then the left when you hit the "doubles".  The air in the H-pipe moves back and forth to relieve this alternating over-pressure and even out the flow through the mufflers and tailpipes, increasing flow.

Or so it was explained to me.

Others talk about scavenging.  When one cylinder fires and the exhaust pulse goes into the pipe, the flow increases.  When the valve closes, the flow keeps going due to momentum and sucks on the pipe behind it.  When the next exhaust valve opens, this sucking helps pull exhaust gasses out of the cylinder more completely.  This slight vacuum behind exhaust pulses is transitory, and so using it on the next cylinder, which is more often than not on the other bank, makes more sense than using it on the second following cylinder, which is on the same bank.

This is what JEGS says on their web page: X-pipe and H-pipes synchronize the balance of the exhaust pulses from each bank of cylinders based on firing order which increases velocity and scavenging from each cylinder. Most people agree that X-pipes are better at improving performance than H-pipes, especially at the top end. However, H-pipes tend to have a deeper sound than x-pipe equipped vehicles and generally build power down low.

Here's where mine is.  It bends under the transfer case output just behind the parking brake cable and ahead of the Flowmasters.  The installer did not use any pre-made fittings.  He cut the holes in the exhaust pipes and brazed the H-pipe into the holes.

[87ChevyR10]

Rich - man, you may have just solved the puzzle. theres way deeper non-related stuff going on aside from what was noted ya dig, but, you answered the main question my pops had as far as finding a picture of what you just showed, cause we chopped it up for a good minute this morning while im in front of a internet connection. so ive used this opportunity to my advantage to narrow things down. i sent him the link, so hes finna bounce back and verify things, but, this is what im workin with.... im finna drop the questions i still have, which are certainly narrowed down at this point.

Headers:

After talking to him, this is what we've narrowed it down to. I trust hedman, and if we're offbase, lmk.

http://www.summitracing.com/parts/hed-69090/overview/year/1987/make/chevrolet/model/r10
The collector attachment is incl which is one question we collectively had, i imagine if anythings not a1, an adapter can be bought and installed ourselves, if thats even needed. I'm 99% locked in on this.... Spoke to summit, wasnt the greatest convo, because the guy was half smart#$$  and said he couldnt give me a deadset answer without knowing if the engine was center/offset to which all i could tell him was i know i have a SB 305 5.0l just like ive already stated, i dont see where its anything other than center, but thats where the convo ended because i guess since i couldnt answer that, he really wasnt willing to go further. And im not in the mood to go back and forth with nobody this morning nor am i willing to lay out the importance of finding out exactly what i need and what this means, so i just deaded the convo at that, but im sure its center and these headers are what i need. Correct me of course if im wrong.

Pipes:
im lost here, need help, pops said i could just go to the shop and let them handle that, but id like to avoid that if possible and let my dude bolt everything up, if anything need be welded, im sure he can handle that/rent whats neededif need be.... BUT i believe everything should be clampable(is that a word? =) ) or bolton, no weld needed. So with that said, summits options on the pipes leaves me at http://www.summitracing.com/parts/wlk-43784/overview/make/chevrolet/model/r10 which doesnt look at all like all whats included on the "kit" should i run with the summit kit. looks like more pipe than this shows. tell me if im wrong. with me piecing all the stuff together, i hate to beat a dead horse, but im tryna be sure. my options aint set to just summit, so if another supplier has what i need based off the set muffler/header options, hit me with it and thats what we finna roll with. I just dont wanna be off at all and be returning stuff.

Muffler:

The super 40 is what im set on, thru summit it doesnt give me the option, it tells me the 70 series big block muffler is whatll fit, but thru advance it lets me choosethe 40. So, wherever i buy it, the only real question i have concerning that specific muffler is the inlet/outlet deal. Since im trying to do the true dual system, im gonna need one inlet/two outlets, one/one, ? To play the devils advocate, if i TOOK IT to a shop, they'll be able to fashion whatever to make it work, but since im lettin my man do the work, thats not all the way the option, and im tryna keep it with letting him do it, so im tryna keep any mandrel bending/welding off the map, str8 bolton/clampon. So, i need the one inlet/2 outlet muffler? This is what i got, is it a problem that the headers say something about collector diameter 3in? http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_super-40-muffler--2-25-offset-in--2-25-offset-out--aggressive-sound-flowmaster-inc-_20290818-p?searchTerm=super+40+muffler+-+2.25+offset+in+%2F+2.25+offset+out+-+aggressive+sound

assuming the header/muffler options i linked are airtight correct/exact fit, the pipes are the only question. My dad said they gotta be right concerning getting around the rear end, etc etc, so, ima lay this at yall hands so i aint gotta have my buddy deal with anything other than the work. Thru the info and guidance thus far, we've got 2/3rds of the equation filled in, help on the pipes. Jegs, JCW, summit, it doesnt matter, drop me a link to the piping at your convenience cause im finna ride from my man house where i got net capability so ill likely be DOA on responding til the 22nd when McDs opens back up and i have free wifi at the rest stop im staying at. I'm about a month off from being able to both get this work done and pay probation to where i can officialy go home with no issue to the law&transferring paperwork as well as the 87 being upgraded/ready 2 ride/make the 300 mi trip home and beyond. Thank you guys for the time, the effort and help. I will be checking for further response as best as i can. Be safe, God bless.

[zieg85]

I know in Indiana any muffler shops will not do any work like that due to the lack of catalytic convertors.  Because a 5.0L never came with dual exhaust they wouldn't do it even if you had them put on 2 catalytic convertors.  As far as I know it is a federal law...

[87ChevyR10]

I know in Indiana any muffler shops will not do any work like that due to the lack of catalytic convertors.  Because a 5.0L never came with dual exhaust they wouldn't do it even if you had them put on 2 catalytic convertors.  As far as I know it is a federal law...

Truck is registered in a county where emissions not needed. I currently reside in a county where its the same case and ima keep the registration where its at so as to avoid going thru emissions and having to put the cat back on. You right though, a shop in this state i believe by law cant legally do that work and str8 pipe it, im not 100% but they have to abide by regulations which would dictate me having to put the cat back on, no str8 pipe. But uh, we going down the block right around that one.

[rich weyand]

You're right, no legit pipe shop is going to fab up a system on an 87 without the cat(s). 

If you go duals all the way back, then the mufflers are one inlet, one outlet on each side.

To do it without cats, you can use a setup for a 78 K truck, which was the last year there were no cats.

If you are going to bolt pieces together with no fab work, then the muffler you use has to be the same length as the originals, or you have to stub in a piece to make up the length difference, or build it up from pieces.  Otherwise the axle hump in the pipe won't be in the right spot.

3" collector is right for the 2.25" pipes.  Get the headers with the stubs/flanges and clamp to the stubs.

Something like this might work.  Lots of clamps and cutting, but all the pieces are there.  You might have to do something like this to avoid cats.  http://www.jegs.com/i/Flowmaster/389/15935/10002/-1?parentProductId=

[Irish_Alley]

high flow cats just to keep the law happy