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post #1 of (permalink) Old 07-25-2002, 05:59 PM
deepnsteeP
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Not happy with my exhaust

Alright........I've been running with this setup for almost two years now and I'm getting a little tired of the loss in low end that I'm experiencing. I've got a new Goodwrench 350 in my '80 GMC. I put on Tri-Y headers and 2.5" true dual exhaust with glass packs. I love the rumble she makes.....but I lose just too much low end with it like that. I need some opinions on what to do here. I want to do one of two different things with it. I was thinking of having an "H" pipe put in or taking out the drivers side dual and just running single again like stock. Can't decide on which would work better. I'm kinda leanin towards the single right now cause it did run pretty good before I put in the new motor and the Edelbrock carb and manifold on that. Would a 2.5" single be a little too much restriction like that or not???? I guess one question on the "H" pipe too if I decide to do that......where is the best place to put that in??? ie....how far from the engine???

I guess I've got one more thing to ask while I'm typing away here.........I'm running 3.42 gears in it and I'm really starting to hate them. Anybody got a set of 3.73 ring and pinion for a 10.5" 14 bolt gm rear and a Dana 44 for the same ratio??? Or......does anyone know of a good place to get 'em??? I called around for shops to get the parts and put them in and it would be about $1500 for the cheapest place here all the way up to $3k at the Chevy dealer.
Any help would be apreciated

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post #2 of (permalink) Old 07-25-2002, 06:02 PM
 
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Re: Not happy with my exhaust

<font face="Times New Roman">
<font color=green>The pipes are too big, that's why you lost the low end. You need to introduce some restriction into the exhaust. You can keep it dual, but you'll need to probably put some more restrictive mufflers in it. You could also just try to crimp the exhast pipes so they restrict flow a bit somewhere in the system and see if that helps. Kind of a backwoods way of doing it, but it might work.
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post #3 of (permalink) Old 07-25-2002, 10:39 PM
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Re: Not happy with my exhaust

Yeah Shaggy I was thinking the same thing, crimping wise. We actually did it to my friends 96 with a 5.7L Vortec that had 3" duals and no muffler. It had no back pressure and was very very rappy at high RPM. Anyway, we crimped the pipe about 18" behind the cats and it worked great. We did 2 crimps per pipe and each were turned 90* from the first one. Actually while we are on the subject, both GM and Ford crimp the pipes on there diesels going to the turbo.

Ryan
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post #4 of (permalink) Old 07-25-2002, 10:40 PM
 
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Re: Not happy with my exhaust

try either stock size dual pipes, or just one large one. i have just one large one, 3 inchs i believe, not sure havent ever measured it, soudns great, course i got a Deisel and they always sounds better [img]images/icons/wink.gif[/img]
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post #5 of (permalink) Old 07-25-2002, 10:49 PM
 
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Re: Not happy with my exhaust

I have the factory dual ehaust set up from when it was a diesel but I cut off the factory mufflers because they where rotted and put on some glasspacks that I had laying around and 23* elbows for turn downs. They stop about 18" from the back rear and I still plenty of tourque but thats probably because I still have the factory exhaust manifolds. Oh and it dosent sound to bad because I used 23" glass packs.
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post #6 of (permalink) Old 07-25-2002, 11:02 PM
 
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Re: Not happy with my exhaust

whenever i decide ive had it with my hill-billy rigged turbo charger, im gonna tear it and my exhuast out and go back to the original true dual exhuast, minus the mufflers
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post #7 of (permalink) Old 07-26-2002, 02:04 AM
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Re: Not happy with my exhaust

Run an H-pipe and ditch the crap packs for some good mufflers. Some backpressure is necessary.

There are lots of theories on placing the H pipe. The one that sticks out in my mind for some reason, is to spraypaint some bright color on your pipes, and then run the engine long enough for the pipes to get good and hot. Supposedly, the place where the paint burned off, not baked on, is the place to put the H pipe (or cross over pipe). I have NO idea how well this works though, I've never owned a dual exhaust. My 350 had a nice big 3" single with a Flowmaster and high flow cat.[img]images/icons/cool.gif[/img] Also remember that we own 4x4's and practical reality means lots of stuff is already hanging down and the object of the excercise to keep things away from the ground. So the best place may not be possible.
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post #8 of (permalink) Old 07-26-2002, 03:04 PM
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Re: Not happy with my exhaust

Drey, what type of Hill-billy turbo did you install. I'm getting close to maybe purchasing a truck with that 6.2l. and I'm trying to get ideas on how to increase performance.
post #9 of (permalink) Old 07-26-2002, 03:33 PM
 
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Re: Not happy with my exhaust

i didnt install it, the guy i bought the truck from did. Its a turbo out of a international tractor. the fliped the manifold on the passenger side of the motor mounted it there. and then ran the air filter off the tractor. its really screwed up looking, hoses running all over and i have to idea what they are for! all i figure is, hopefully either it will start using alot of oil, or the motor will blow, and then ill swap the motor in out of my other deisel pickup, and tear out all the crap for the turbo, and put in dual exhaust like the truck is supposed to have, personally i dont think it helps much, but then again i havent driven the truck awhole lot
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post #10 of (permalink) Old 07-27-2002, 06:38 AM
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Re: Not happy with my exhaust

[img]images/icons/tongue.gif[/img] If you've read my posts to the MX Kid about the overheating problem you'll see that I have several million miles logged in the '73 to '80 model years.[img]images/icons/tongue.gif[/img] Believe me when I tell you that I have been THE ROUTE on FS GM pickup exhausts. What I've found is that the 350 CID engines don't seem to work well with duals; either 1-3/4" or 2" pipe. I haven't tried 2-1/2" per side, but I DOUBT if it would be an improvement. MY BEST performance has been with an OVERSIZED SINGLE exhaust. The first one I made was a stock wye pipe with the stock 2-1/2" header to the catalytic converter and then a specially constructed 2-1/2" tailpipe and a NAPA drive-through muffler. It was a HUGE increase in performance. I also dumped out the berries that were in the converter[img]images/icons/shocked.gif[/img] and ran them through a screen such that I ended up with only the large dimeter ones.[img]images/icons/tongue.gif[/img] I refilled the cat with the large berries and put the rest in a coffee can on the shelf in my shop. The pickup passed the CA smog tests with flying colors.[img]images/icons/smile.gif[/img] THE NEXT exhaust system was a totally-custom setup since the entire exhaust system was crapped over by the previous owner In this latest setup I have 2" header pipes from the manifolds; the RH side crosses over just behind the clutch and IS EASILY REMOVEABLE to drop the tranny or the clutch; the LH side goes straight back, and they BOTH enter a two-in, one-out FLOWMASTER muffler. I have a three-inch single tailpipe. This setup has the sweetest sound you ever heard when that Goodwrench is sitting at 3500 and you can hear the sound bouncing off a guardrail as you pull the Rockies with 20,000 gross weight. Oh yeah, we also heat-wrapped both header pipes all the way to the Flowmaster. Keeps the floor pans cooler on those hard summer pulls.[img]images/icons/crazy.gif[/img] We took the time to split the transfer case levers last year, and that gives us more useable gears to pull with. One of my favorite grade-getters is THIRD UNDER which runs us about 25 MPH at 3500 RPM.[img]images/icons/smile.gif[/img] That exhaust is really TALKIN' to us......jus' like MUSIC![img]images/icons/crazy.gif[/img]
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