hey all, my first post on this forum... I recently got a K5 blazer with 350...

Need to do something about the exhaust ASAP!

has the factory single exhaust, which I will remove all of...

Does anyone know how difficult the install would be for some headers on this vehicle? - I have an 8" suspension lift and 35's, so that helps I think if they need to go in from the bottom.

thanks in advance!

 

What year Blazer is it? If it's a 73-87 body style, it's cake. You can drop them straight down or from the bottom with no problems. I had an 86 Silverado and I put on some Flowtech longtubes and they dropped straight down, didn't have to unbolt anything. For a 350 I recommend 2.25" to 2.5" duals with a crossover, if it's the 73-87 body style you can run pipes down each side which makes it a lot easier.

 

Blazer's an '87. appreciate the info on the headers... since it's lifted a lot, looks (after closer review) that I can get them up from the bottom.
as far as the rest of the exhaust, 2.5's way to small for me... the plan is to duplicate an exhaust system from a car I recently got rid of... just go from the collectors on the header with 3" (so there's no neck-down of the pipe) into 12" of 3" pipe and some one-chamber 10 series Flowmasters, then turn downs on the end of those.... so the whole exhaust system about 18"-20" past the headers... (yes I am looking for it to be loud, I want it to sound throaty and healthy)

 

If you're making 400hp or more, then 3" is fine but for a stock to mild 350, 2.5" is plenty. If you go with 3" on stock then you'll kill your low end, it'll be a pig on takeoff and being a truck the low end is where you want most of the power.

 

I see what you mean, I certainly realize that it doesn't NEED 3" for performance... but I can't and havent been able to find a different way to get the sound I want. - I had this exact exhaust setup on a medium built 283... and it sounded like a hot big block.... everyone always called me a liar when I told them it was a small block...

I'm looking to make it sound deep and aggressive and very loud... - I've had 2 chamber flowmasters before and they are just too quiet for my taste.

that being said... I am trying to understand how youre saying it'd LOSE power (low end) to have a more free flowing exhaust... - the way I see it, more restriction=less power, less restriction = more power... that's why drag cars run open headers and such???????

 

Drag cars have more power than most street cars, they use stall converters and launch at a higher rpm where they make more power. Yes less restriction means more power but at a certain point it's too much. You need high exhaust velocity to make power and with pipes too large it doesnt flow fast enough, it's like a garden hose, it flows out slow but cap it off a bit and it flows faster, cap too much and not enough comes out quick enough. You have to size the pipes according to power output for power at every rpm.

 

add onto what 88vic said...





drag cars have high stall converters, etc so they are taking off at a much higher rpm and are hitting peak hp right away and have extremely done motors. the low end(tourque) will suffer... but they don't run in the lower rpm ranger...

I got true duel 2.5's on my blazer with glasspacks... love the sound... and got goot all-around power

friend removed the cats for his street build(mines a trailer queen now) and never welded in pipe to complete the exaust so I am running open headers... it runs like a bag of S*%$T!!!! I got power at higher rpm's and is loud as hell... but I can barely get the truck moving from a stop....

 

Same with my 86 Silverado, I had a 260hp crate motor with a Voodoo cam and Flowtech longtubes, I had 2.5" duals with an H-pipe and offbrand Flowmasters on it. The exhaust after the headers was all it one piece so I unbolted it at the collectors to re-weld the mufflers on and I decided to drive it around open longtubes for the hell of it. It sounded awesome because of the cam and headers, for a while but besides giving me a headache from being so loud, it was a pig and there was a huge difference in take-off power, like nothing I had felt before. Up until that point I never realized how important pipes are to performance.

 

I do appreciate your info...it is helpful, and perhaps the performance change is a bigger deal than I thought it would be... so when you say that you will see a power difference, how much are we talkin? - like 5hp? - or?????

here's a diagram of what I want to do... this is exactly the configuration on my previous car, and it's (in my opinion) the best sounding car I've ever heard... since my truck has a big lift I want it to be real loud and powerful sounding... - do you have a suggestion on what to do different here than my plan to make it perform better without losing the sound????

I do care about performance, but ultimately, my reason for the exhaust here is to make it sound good. (I realize good is subjective and not everyone likes "super-loud", but I do )

 

Look at it this way, I have stock 2" duals on my Suburban and the stock 2.5" tailpipe and it has a very smooth, deep rumble to it. It depends a lot on the engine (being a V8 helps the most) and the setup so I guarantee you that setup in 2.5" will be loud and have a very deep tone to it. Also to aid in both sound and power departments, put in a crossover, either an X or H pipe. Equalizing the exhaust pulses not only gives it a smoother and deeper sound without making it quieter, it also increases scavenging (the effect of pulling gases out of the cylinders the same way longtube headers are designed to do) so it increases torque and horsepower at every speed.