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engine damage from true duals?

Explorer Junky

Well-Known Member
March 15, 2010
Reaction score
City, State
Grand Rapids, Mi
Year, Model & Trim Level
1997 XLT 4 dr 5.0
I have been reading around on the forum. From what I can gather, there seems to be some type of belief that if a 5.0 runs a true dual system, that it can result in engine damage? Is this true?
I have a 5.0 with 1.7 full roller rockers, TMH's, Magnaflow cats in all 4 positions, 2.25" pipes into 2.25 in glass packs, then out the corners. Do I have enough back pressure? I have read that some prefer the 2 into one. I had a two into one Magnaflow installed a few years ago and it actually felt like it lost something in take off. I am looking at updating my exhaust this fall to a 2.5" system with the same set up. Any ideas?

I will probably be in the minority...

But a dual exhaust system on most any engine can benefit the performance by removing more of the spent gases and providing a vacuum on the outlet side of the exhaust valve if the design is correct...

The biggest issue most people have is using piping that is way too big...The theory of proper exhaust flow is based on the velocity of the gases coming from the engine and using that velocity to help generate a vacuum on the ports that are not opening...

The idea of back pressure really needs to go away...ANY restriction in the exhaust is a restriction against the power making ability of the engine... Every gasoline engine burns fuel and oxygen and a certain amount of that fuel/oxy mixture remains in the cylinder to contaminate the next fuel/oxy charge...If the exhaust velocity is maintained in the headers or even manifolds and the rest of the system is designed to enhance the flow velocity there will be a vacuum or scavenging effect on the exhaust system to help pull the residual spent gases from the cylinders and into the exhaust system...

I will give you an example...My 99 Sport has a 4 liter engine with 2.25" pipes from the manifolds out to the 2 tailpipes out the back of the truck...I seperated the 2 inline catalytic convertors and run them in parallel as well as an x-pipe at the front flange of the dual pipes and made certain the 2 pipes stayed seperate and feed the hi-flow convertors and then go into a Magnaflow dual in/ dual out muffler and then into 2 tailpipes....

When I removed the single exhaust from the truck I noticed an improvement in overall driveability...I have installed larger port manifolds from a 96 to my 99 and I can't tell you that I regret a second of the work I have done on this truck...I still have a few variables to work out such as running headers instead of manifolds and trying an H pipe instead of the x-pipe that I currently use and using header wrap on the downpipes to keep more heat in the pipes and maintain more of the velocity in the system......

So far I have noticed no change in the new engine I installed last year and the plugs are running a bit cleaner and the fuel mileage is better than it has been... I have noticed no decrease in compression or any additional metals in the oil from the analysis I have had done...

Granted this is just my opinion and I have applied these theories to a few vehicles I have worked and experimented on in the past and the present...Keep an open mind and stay firm to what you want to do with your truck and find a shop who understands exhaust velocity and laminar flow and I think you will be pleasently surprised...

Thanks. That was a very well thought out response.

I'm putin true dual straight pipes on my 99 X with a sohc 4.0 2.5 inch pipes out the back dumped with 3.5 tips,,,,I'm gunna put straights on it regardless I was just wondering about the size of the the pipe