does the 6.2 need backpressure ?

[axemurdock]

I cut the mufflers off my m1008 so the pipes let out a foot after the cab. Sounds like crap, disgustingly loud. Do I need mufflers on it to run good , do I need back pressure like a gasser? Ill weld sleeves on so I can attach the tail pipe section so it'll exit in stock location , near rear bumper and curved out. It shouldn't be that loud I'm guessing but will that be enough backpressure for it?

 

[beanman1]

i think there was a post on here about this but i also do believr scince there is no turbo on the 6.2 to give the back pressure i woild assume that it would need some kind i have heard some 6.2s that had the glass pack mufflers(cherry bombs) on them that sounded real good i would try that instead of straight pipes they are pretty cheap about 20 to 30 bucks i think

 

[Shop Rat Fab]

160 horsepower out of a 6.2 what are you looking to gain with no mufflers beside noise? My opinion leave the mufflers so your truck is not annoying. You can run straight pipes its just going to be loud, backpressure is not an issue.

 

[doghead]

I'd go strait pipes with 6" stacks in the bed! maybe a sweet sewer pipe intake snorkel(to collect rain water) Bald big ole tires and a boomin sterio.... don't forget the scrotum under the bumper too...

 

[Shop Rat Fab]

Lmao

 

[beanman1]

 

[axemurdock]

The stock muffs that were on was rusted and holy. Time to take them off & change them so I was just checking my options. funds are low so I wanted to go the inexpensive route with strait pipe till I can buy new mufflers for it. Thanks for your replies.

 

[Shop Rat Fab]

axemurdock, Thanks for the rest of the story.

 

[Westech]

ok FNG's... oops I mean new guys. Sorry. Here is the deal with "back pressure" A engine needs 0 back pressure to run and run well. What pipes and mufflers are for is to reduce noise and rapid cooling of the valves. Have you ever cooled off a frying pan in the sink when it was hot and it warped? Well I have and that is what valves do if cool air can get to the valves after the engine is shut off. Thats why you see drag racers put balls or cups over the pipes after the engine is shut down. YOU NEED EXHAUST PIPE ON THAT ENGINE!! a couple feet may not be long enough to prevent rapid cooling. YOUR ASKING FOR IT!

Love Westy.

 

[Cucvnut]

aww I miss westy's posts !

 

[mistaken1]

I'd go strait pipes with 6" stacks in the bed! maybe a sweet sewer pipe intake snorkel(to collect rain water) Bald big ole tires and a boomin sterio.... don't forget the scrotum under the bumper too...

Now you done hurt my feelings, I have been trying to come up with a way to hang a pair of bowling balls off the back of my deuce!

LOL

 

[doghead]

Speaking of backpressure, What's up your tailpipe lately, Westech?

You better not be skipping your anger management classes and going to the track(betting Jackson's lunch money).

 

[Westech]

Hey I said I was sorry after the FNG remark.

 

[militarytrux]

funny to hear the opinions of the pros here, if your worried about the valves getting cooled to quickly and ruining the heads then I better run out and find a softball to stuff in the stack of my deuce, I have put 30k on it over the years and as far as I can tell theres no muffler on it and the overall pipe length might be 5' dont think the valves mind at all.

 

[Westech]

umm... the turbo does not cool right off there guy.. there is a little more mass to it then a foot of exhaust pipe. Try again. 16 year Master ASE

 

[kipman]

What a junker.

 

[wkbrdngsnw]

Has anyone actually ever seen a valve crack from thermal stresses due to no exhaust system? It seams to me that conduction and radiation from the head would keep it relatively warm. I don't see a lot of flow going back into the cylinder since it is a fixed volume that isn't going to cool off fast enough to create the movement of the volume of air needed to cool it off quick enough to crack it. Maybe if there was just an open port with no manifold. But I guess anything is possible.

 

[Tanner]

160 horsepower out of a 6.2 what are you looking to gain with no mufflers beside noise? My opinion leave the mufflers so your truck is not annoying. You can run straight pipes its just going to be loud, backpressure is not an issue.

Engines DO need a small bit of back-pressure in the exhaust system for optimum performance & exhaust scavenging... not so much that you kill flow, but then again, a 6.2 is not a high-revving, high exhaust flow motor like a 7000rpm Honda engine. You're looking for a balance in the piping to create a slight 'vacuum' as the exhaust gasses flow out the tailpipe.


'Tanner'

 

[Tanner]

ok FNG's... oops I mean new guys. Sorry. Here is the deal with "back pressure" A engine needs 0 back pressure to run and run well. What pipes and mufflers are for is to reduce noise and rapid cooling of the valves. Have you ever cooled off a frying pan in the sink when it was hot and it warped? Well I have and that is what valves do if cool air can get to the valves after the engine is shut off. Thats why you see drag racers put balls or cups over the pipes after the engine is shut down. YOU NEED EXHAUST PIPE ON THAT ENGINE!! a couple feet may not be long enough to prevent rapid cooling. YOUR ASKING FOR IT!

Love Westy.

Ahhh, yes... the mythical 'short exhaust pipes burn valves' story...

If there were any truth to this story, then every piston-powered warbird from WW1 & 2 would have toasted/bent valves, as would straight-piped Harleys & V8 car motors used in dragboats that utilize unmuffled header pipes, etc.

In the instances where I have seen bent/burnt valves on engines with straight pipes, the damage occurred due to leaner fuel/air mixtures caused by the removal of the exhaust restriction; e.g., no more muffler - thus, the engine was out of balance on its air/fuel mixture & it was never tuned back to the proper A/F ratio... it wasn't caused by the mythical 'shock cooling' myth.

Consider this: how does cool air suddenly rush back up into the short exhaust pipe & hit the valves? You've got a lot of heat-mass sitting there in the cylinder head at shutdown that will take a lot of time to cool down. Most exhaust valve heat transfer occurs through the valve face to seat; less of the heat transfer occurs through the stem to guide.

And straight pipes sound like crap - run some mufflers.

'Tanner'

 

[hovenga67]

I seen a friend mine blow a hole through a valve on a ford four banger running basically just a manifold for 6 months.
Brent