Too much air?

[cpizz]

Can you have too much air flowing through the engine? If you have intake enhancements(i. e. intake baffle removed; silencer ring removed; air box modification; and aFe filter) and a 5 inch exhaust, will it effect the performance? This is also without adding a "box". If so, what would it cause the engine to do?

 

[Vaquero]

I was wondering the same thing. I was talking to a former OTR driver that works with us and he said that a free flow exhaust (no back pressure) would "float the valves". This sounds like B. S . to me with all the people that run free flow exhaust on pick-ups and trucks whith no problems that I have heard of.

Don't mean to hi-jack your thread but thought we might be wondering the same thing.

 

[HillCountrykid]

A turbocharged diesel pretty much can never have too much air. The more air, the better. The turbo pretty much determines how much air is going in and coming out of the engine.



"Floating" valves is when the engine is turning high rpm's and the lifters cannot follow the profile of the cam, which has nothing to do with airflow. I imagine its pretty hard for most of us to float vavles in our engines at the rpm's most are running.



Brian

 

[Prairie Dog]

One of the aftermarket exhaust companies ( I forget which one) posted here a while back and said they actually saw a slight decrease on the dyno when they went to a full 5" exhaust over a 4" inch system. I know, I can't explain it either but they saw what they saw.

 

[Blakers]

Originally posted by Prairie Dog

One of the aftermarket exhaust companies ( I forget which one) posted here a while back and said they actually saw a slight decrease on the dyno when they went to a full 5" exhaust over a 4" inch system. I know, I can't explain it either but they saw what they saw.

It may have something to do with the scavenging effect of the exhaust flowing through the pipe. The exhaust gas must flow faster through the smaller pipe - this higher velocity flow may actually increase the turbo's efficiency at certain speeds or loads.

 

[mconstable]

I don't know the reason behid losing power with too big an exhaust, but growing up with musclecars, it was the same thing, you get to a point with exhaust getting bigger where you're sacrificing bottom end power if you go bigger, doesn't apply to an all out race car, but every-day driving, you want the bottom end strong, just my 2 cents

 

[bmoeller]

Originally posted by Prairie Dog

One of the aftermarket exhaust companies ( I forget which one) posted here a while back and said they actually saw a slight decrease on the dyno when they went to a full 5" exhaust over a 4" inch system. I know, I can't explain it either but they saw what they saw.

Originally posted by Mark Craig

Rluft,



I may get abused for this but, in our testing unless you have a seriously wild truck with nearly every mod that can be done to the engine the 5 inch is too much. I am not a mechanical flow engineer but have worked with them in the process of new system designs and the flow capability of a true 4 inch mandrel bent system way out flows the output capability of the 5. 9 engine. We have also seen a movement of the torque curve upward into the rpm band when a 5 inch is used. Most folks want a diesel for low rpm torque and moving the curve up is now helpful.



Now if you're into sled pulling and making the max hp and torque now matter what the rpm then 5 inch has it's place. There are those that like the sound of 5 inch too, and get it for that reason alone. Call us if we can help you, we've been down this road already and can save you the time and effort.



Mark Craig

DPPI

For me personally, I have no problems with the 5". I have not lost any low end power whatsoever. The turbo and engine are VERY responsive. Virtually no turbo lag at all. My milage has come up just a little. Generally about . 5-. 75 mpg gain. Sounds GREAT!

Very happy with it.

 

[GWDiesel]

5 " EX. power loss

Yes, When I installed my 5" EX system I noticed a slight drop in

low end esp. in 2nd. and 3rd. gears,but a little more pull in 4,5, and6 th. gears. And a small drop in fuel milage! I think the computer has somthing to do with this! I love the sound(5"muffler

Donaldson with one baffle)Would I do it AGAIN? You bet,I am very

happy wirh this setup. Bone stock Motor,till the 7/100. 000 is up.

GWD

 

[JHardwick]

We can actually tune 800hp sprint engines on the dyno with exhaust. The power loss you experience with the 5" exhaust is actually just misplaced.





A longer/smaller collector with enhance lower RPM torque, and a shorter/fatter collector with increase high end HP.