Exhaust ideas?

[parb]

Hi all,

I need the change it my exhaust as it is just rusted through. I'm thinking that I'm going to put in a 2.5" exhaust. I'm considering the borla xs mufflers with an H pipe. Any thoughts about this idea?

Also I'm thinking that I'll change the exhaust manifolds to 2.5" ram horns. What do you think about this? Any recommendations of which horns to buy and where to get them?

I got a 72 GMC Jimmy 4x4.

[Mike C]

I replaced my headers with the 2 1/2” rams horns and went from 2 1/4” to 2 1/2” exhaust at same time. No balance pipe on mine and I have what used to be called the Dynomax Hemi Turbo mufflers with 20” case. I have been very very happy with this setup which is 10+ years old now.

The last ramshorns I bought came from Speedway motors but I’d bet they are all made in same factory.

[parb]

I'm tempted to do what you've done. Since I've posted I have come across a few threads that scares me... Tales of broken bolts in the engine block when removing the exhaust manifolds. I got to think this through to see if the rewards are worth the risk.

...or am I being overly cautious?

[SeventyOne]

Parb - I have corvette 2.5" manifolds I was going to run on my Blazer but went headers instead. I cut off the accessory brackets and painted them both with high temp "cast" paint.

They looked like this before I cut off the bracket:
https://www.speedwaymotors.com/Corve...fold,9133.html

Actually you can see them here also mounted to my engine. Never ran - look great still.
http://67-72chevytrucks.com/vboard/s...&postcount=122

I'd sell them to you for $100. Can get you pics tonight. I'm local and will be in mountain view on Friday/Saturday.

[parb]

I checked your thread. cool! What made you change your mind on the exhaust manifolds vs. headers?
In your thread it looks like you had to change the motor mount by 1.75"? Did i read that right? I'm trying to buy something that will fit without me having to make any changes.

[SeventyOne]

I'm running a 700r4 Trans so I moved the crossmember forward to accommodate the longer trans length. These manifolds will fit in the stock location as well.

I went headers because they look better in my opinion.

[parb]

Ah, so since my truck is bone stock engine and transmission the manifolds should fit without any changes?

[SeventyOne]

If you're already going to replace the rest of your exhaust system yes. These manifold have a straight down exit - i think the stock manifolds have an angled exit. Could be wrong.

Either way any exhaust shop should be able to get you the correct down pipe to make it all come together.

[parb]

Its worth $100 to figure it out. I'm out from wednesday to monday (in new york).
Are you around next weekend?

Or if you prefer, I have teenager who is watching over my dogs, i can ask him to meet with you in mountain view and get the manifolds and give you money if you prefer anytime Wednesday to Monday.

par

[SeventyOne]

I'll send you a PM.

[mister.freeze]

What were you running before that is now rusted through? I have true dual thru short flowmasters exiting sideways before the back tires. Cool 19 years ago when I was younger & running a stroker. Thinking about adding an H pipe now...

[jaros44sr]

Originally Posted by parb

I'm tempted to do what you've done. Since I've posted I have come across a few threads that scares me... Tales of broken bolts in the engine block when removing the exhaust manifolds. I got to think this through to see if the rewards are worth the risk.

...or am I being overly cautious?

You can always use studs, instead of bolts, with brass nuts, if that concerns you. I'm running cast iron 2 1/2" manifolds from dormann, just cut off extra mounting flange that will sit against firewall

[hemi43]

Headers will give you nothing but grief, and will not do anything to improve performance on a stock engine. Stick with cast manifolds. The H-pipe will be difficult to fit in the Blazer if it's 4WD. I made my own exhaust from 2 1/2 304 stainless and could not find anywhere to get that H pipe in without having it interfere with something or hanging too low.

[mister.freeze]

my thoughts were to bend it under the torque converter, between the 2 pans. The H pipe doesn't get too hot, does it?

[87Skier]

Originally Posted by hemi43

Headers will give you nothing but grief, and will not do anything to improve performance on a stock engine. Stick with cast manifolds. The H-pipe will be difficult to fit in the Blazer if it's 4WD. I made my own exhaust from 2 1/2 304 stainless and could not find anywhere to get that H pipe in without having it interfere with something or hanging too low.

Definitely a problem for the 4wd stuff. Still thinking about putting one in mine, but haven't come up with a good way to do it yet.

I'm hoping adding in the H pipe will make the exhaust sound more uniform and not as much as like a loud motorcycle.

Also, I used the hooker header back system. I wouldn't recommend using this. The rear sections are the only pieces that fit correctly. Had to figure out my own way by the transfer case.

[hemi43]

Originally Posted by mister.freeze

my thoughts were to bend it under the torque converter, between the 2 pans. The H pipe doesn't get too hot, does it?

Do some research on where to put it. If I recall, there is a sweet spot to locate it. Not too sure about the heat, but I do agree the exhaust note is a bit nicer.

[SeventyOne]

before i tore my Blazer apart there was an H pipe that went under the rear Tcase output. I dont recall it hanging too low. Fit pretty tight up there.

Sorta crappy pic here:
http://67-72chevytrucks.com/vboard/s...85&postcount=1

[hemi43]

Originally Posted by SeventyOne

before i tore my Blazer apart there was an H pipe that went under the rear Tcase output. I dont recall it hanging too low. Fit pretty tight up there.

Sorta crappy pic here:
http://67-72chevytrucks.com/vboard/s...85&postcount=1

Like mentioned before, if there's any major heat I don't think I'd want it near my U-joints.

[SeventyOne]

Hm I think that would have to be a lot of radiant heat to soak into a ujoint and affect it, but sure. I'd be more worried about it being too close to the transmission or starter if it was in front of the trans.

When I get around to doing my exhaust I'll try to do an h pipe or x pipe just rear of the tcase again.

[simicrintz]

Not sure if any help (kinda tough to get pictures under there!), but here's a few of mine. '71 Blazer, manual trans.

[SeventyOne]

Great pics and placement for the H pipe.

[parb]

I agree, great pics and great advice.
Did you use a narrower pipe in the h connection than the rest of the system?
The pics looks like the h is a smaller diameter pipe but I wanted to confirm.

[simicrintz]

2 1/2" pipe with 2" crossover. Why 2"? Good question.........

[mister.freeze]

Originally Posted by SeventyOne

Great pics and placement for the H pipe.

Mine exits in front of the rear tires. Might my system be too short for an H pipe in that location to be any good?

[Harold Holbrook]

I found a set of GM truck Exhaust manifolds 2 1/2 in. put a bolt in it were the front bracket goes than cut and ground it off. Looks good cant see bolt.