headers on stock tbi 350

[black dawg]

Just wondering if headers are gonna help much (powerwise) on a bone stock tbi 350. This is on a 3/4 ton burb for towing.

 

[sweetk30]

comon topic last month or so. simple search should pull up this stuff. but here is basics.

shorty bolt on headers with custom 2.5" ypipe to 3" single 3" out threw high flow cat and 3" muffler in/out should on average get 30-40 hp at the rear. dyno sheet proved this on another site few years ago.

 

[black dawg]

thanks, I tried searching but I get sucked into some zillion page build thread every time.

 

[nsxxtreme]

thanks, I tried searching but I get sucked into some zillion page build thread every time.

Actually IMO a highflow cat and good muffler will do more then just sticking headers on it. I'm in the opinion that headers aren't worth the hassle associated with them

 

[sweetk30]

not on tbi truck motors for some reason. and the shorty ones seem to work better also than long tube's

 

[nsxxtreme]

not on tbi truck motors for some reason. and the shorty ones seem to work better also than long tube's

I have the shorty headers and did the hi flow cat and muffler first. I thought and felt a performance improvement with the cat and muffler. The header I didn't feel any noticeable improvement and they are just a pain in the butt.

 

[metalneverdies]

Not to thread jack, but what are the prefered brands of hi-flow cats and mufflers?

 

[nsxxtreme]

Not to thread jack, but what are the prefered brands of hi-flow cats and mufflers?

This is the Cat I used http://www.ebay.com/itm/3-Goerlich-...pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr

You can search my user name when I was asking for mufflers to see which one I ended up with. I forget and am to lazy to look.

 

[smier]

I used the flowmaster 3" catback kit on my '91 Blazer with a 3"straight-thru magnaflow universal cat. I had to buy a 3" section of straight exhaust pipe and cut it to fit to help make up the difference in length on the cats. Has worked great on my '91 with a stock motor with factory manifolds. It definately has more pep and helped with the mpg's as well, but my old cat may have been almost plugged for all I know... A lot of guys have said you need to replace the y pipe because it doesn't flow well and it's not 3", but my factory y pipe is 3" from where the two pipes meet, so I'm wondering if the older trucks have a smaller y pipe? I daily drive mine 40 miles, so my mods have more than paid for themselves. I'll edit in a link to my thread in a bit, it has part #'s and prices from summit racing. I hate headers personally, I've never had much luck with them not leaking.

Exhaust kit is obviously for a blazer, but hopefully helps you out:

http://coloradok5.com/forums/showthread.php?t=284885

 

[blazinzuk]

Hey woodchuck you gotta a link there for that test somewhere,

Dang thats well worth the hassle of headers

Guess I need to start looking for headers, engine is one thing I have not messed with at all on Horton

 

[tRustyK5]

I'd love to see test results proving 30-40 hp at the rear wheels too. I just don't see that being a reality without some other mods too...

 

[nsxxtreme]

A lot of guys have said you need to replace the y pipe because it doesn't flow well and it's not 3",

I replaced the y-pipe on mine. I'm fairly sure mine wasn't stock though. It just looked like a pipe that had another pipe connected to it.

I'd love to see some dyno measurements proving headers alone add 40hp. I'm just not buying it. I replaced the cat, muffler, y-pipe and actually noticed an improvement I could feel. However replacing a set of brand new exhaust manifolds with a set of headers the gains were insignificant.

Speaking of that if someone needs a set of stock exhaust manifolds that are essentially brand new ( i think I used them 4 months) I would sell them for a good deal. Just send me an IM if interested I think I paid about $300 for the set.

 

[sweetk30]

brian at www.tbichips.com

basic tbi mods and exaust with links to parts is listed. http://www.tbichips.com/truckmods.htm

and says to check this build thread for the results. " there was 40hp/50lbs of rear wheel power numbers from just that Y pipe change " http://www.tbichips.com/blackmagic.htm

thats what i have read from his stuff few years ago. unless i miss read somthing here.

 

[tRustyK5]

Yup, 40-50 hp change after modding to a better Y-pipe, headers...all on a fairly modified TBI small block.

I'd guess no better than 10-15 hp on a dead stock TBI 350.

Headers can really help, but on a stock engine you aren't gonna hardly notice anything more than 'sound'. Same goes for a modded engine still running manifolds and restrictive exhaust.

Dyno a 454 with a great cam, single plane intake, etc etc and 2" single exhaust...then compare it to a dyno run using great headers and appropriate exhaust. Did the exhaust make all that power difference? I say no, it was just the final piece. It's about matching parts properly.

Great flowing exhaust on a stock engine doesn't help a lot. It's not flowing enough fuel/air etc to make it worth it.

I want to see a dyno comparison on a dead stock TBI 350, then another with just shorty headers, and a final one with a complete high flow exhaust. That'd tell you the real story.

 

[nsxxtreme]

thats what i have read from his stuff few years ago. unless i miss read somthing here.

I think most of that power came from replacing the cat, muffler and Y-pipe. Which I would agree 40/50hp IMO is what it feels like.

Would be good to see a dyno of JUST changing the stock manifolds with headers. I don't think you will see much. I also don't think you will see much of a gain replacing the stock manifolds with headers AFTER replacing the cat,muffler, y-pipe. That's JMO I have no data to back that up just my butt dyno.

 

[wayne]

I went from stock to high flow cat and flowmaster 3" cat back. I didn't notice that much of a change. Then I went to headers, no cats, and true 2.5" duels with flowmasters. I noticed a little improvement but nothing that overly great.

 

[smier]

I agree, no way a 40 to 50 hp gain on a stock TBI motor. I am pretty confident that my exhaust changes now flow better than our awful stock cylinder heads can manage. This stuff has been pretty well documented on Thirdgen.org, remember guys used to drag race with these TBI setups until LS motors became so popular and cheap as a swap. There are even guys in there that dyno'd all these setups, they have pretty well proven our stock heads suck, and its where I came up with all my mods for my Blazer which I eventually would like to put a mild 383 into. If I ever get that far, then I would put on a set of quality shorty headers and a new y pipe.

 

[black dawg]

Are there any dyno tests to show how tbi heads act compared to vortecs or old school heads like 882s

My tbi motors have WAY more low end grunt than my old carbed motors.