3" exhaust upgrade

[Martin White]

Has anyone here done this and recorded accurate fuel consumption and power data? I have the stock exhaust on my truck currently - I've read some good things about the aero turbine system. If I do this I'd go to a 3" (or more if any advantage) system from one end to the other. Thoughts?

 

[The Dude]

it's heat. you'll save (or I guess lose) heat. Unless you have something really undersized on your rig now, going to a bigger exhaust will only drop EGTs... Which is a really good thing.

but don't expect performance gains from an exhaust system...

 

[SamB]

I would like to get this done this weekend! been planning it for a while now!

I'll record accurate (well accurate ish) data of fuel consumption, boost increase/decrease etc before and after.

Everything I have heard or read says you will gain something out of a bigger exhaust....

 

[crushers]

the turbo will spool up faster and the EGTs will be lower...

 

[Jim_Hbar]

Martin:

The first thing I would do is check out the resonator on the stock system. Check out this thread for my results.

https://forum.ih8mud.com/showthread.php?t=72355

 

[harveya]

As wayne said, 3 inch on a 1HDT will improve turbo spool up, increase low down power and torque, reduce engine temp.

economy will also likely improve but not by much maybe 1 or 2 mpg at most because the engine will work less hard.

3 inch exhaust is a great upgrade for the 1HDT, 1HD-FT and to be honest even the smaller engines.

 

[The Dude]

increase low down power and torque

I would challenge you to prove this on a dyno. I have never seen an exhaust only change give better numbers on a dyno. Ever.

economy will also likely improve but not by much maybe 1 or 2 mpg at most because the engine will work less hard.

Not sure about this either. If ONLY larger exhausts made that much of a difference then all our cars would have large exhausts from the factory so that they could claim better MPG ratings for the EPA...doesn't make sense to me

Sorry if I seem a little fiesty, but larger exhausts do one thing, get your EGTs down by increasing flow away from your engine.

 

[crushers]

i have to agree with Dude here, after chatting with the guys at the local turbo shop i asked them specificly about the larger exhaust ie 6" on a ford vs the stock and their reply was the is no differnce on the charts from the dyno. it sounds cool and drops the EGTs...
as for fuel milage i never worry as long as i am doubling what a simular gasser is pulling in...
cheers

 

[harveya]

It doesn't increase total power, just ups it a low revs because the turbo spins up better. A bit like removing the EGR valve on a 2LT. I also doubt that maximum power or torque would increase but I have seen well documented experiences on the 2LTE about increasing the exhaust size and also some experiences on the 1HDT.

 

[108Cruz]

I checked my exhaust system on my LJ71. I do not have a resonator in the system. It only has a muffler and piping and it looks stock. I knocked and wiggled on the pipes and muffler and every thing seems solid and hardly moves at all.

Would there be any difference to the exhaust , performance wise, if you just replace the stock muffler with a low restriction one and leave the rest alone as mine is good and solid now ?.

Does anyone know the stock pipe thickness for an LJ71. I do not have a tool to see what thickness the pipes are.

Thanks

 

[SamB]

i have to agree with Dude here, after chatting with the guys at the local turbo shop i asked them specificly about the larger exhaust ie 6" on a ford vs the stock and their reply was the is no differnce on the charts from the dyno. it sounds cool and drops the EGTs...

I think this is true as well, however as you start increasing the airflow into the engine and upping the fuel, you will notice the benefits of the bigger exhaust versus stock exhaust (stating the obvious I know LOL)

 

[Mickldo]

My standard exhaust on my HZJ80 had a resriction where the pipe went up and over the rear diff. Since fitting the turbo and the 3" it is just a nice smooth mandrel bend up over there now. The resriction was where the pipe was squashed to about half its diameter to go over the crossmember.

I personally recommend the 3" system but you might be able to replace that resriction for a bit of an improvement.

 

[Tapage]

I thought when you go with larger exhaust you loose some torque at low rpms .. coz you have less backpressure ..

 

[cruiser_guy]

I thought when you go with larger exhaust you loose some torque at low rpms .. coz you have less backpressure ..

Back pressure is BAD!

 

[Technikev]

I thought when you go with larger exhaust you loose some torque at low rpms .. coz you have less backpressure ..

That's usually only typical of a gasser. Back pressure is not good for diesel performance.

-kevin

 

[bigbrowndog]

The standard system was not letting my turbo maximise its boost at all ,the 3inch mandrel system is far better no comparison


. Also the turbo runs a lot quiter and cooler.The standard system on my hj75 was 2 1/4 inch to the muffler then 1 7/8 after it.

 

[Tapage]

That's usually only typical of a gasser. Back pressure is not good for diesel performance.

-kevin

Good to know .. I thought this weekend I go for a 3 inches exhaust ..

 

[hks3sgte]

I thought the backpressure thing was valid for all non-turbo engines? Turbocharged engines do not need any backpressure to run more efficiently... in fact, they're better off without any backpressure...

 

[dieselcruiserhead]

That's usually only typical of a gasser. Back pressure is not good for diesel performance.

-kevin

Backpressure is bad for a TURBO diesel, for a NA it is the same as a gasser. Basically the turbo adds the back pressure, they still need it, usually...