3 1/2" turbo Turndown better than 4" ????

[EFickbohm]

I was asking a guy ( owner of a shop in saltlake) which exhaust sistem

he would recamend for a early 04 I am buying tomarow.

He said he gets better dino results with the 3 1/2" becaus the turbo spools

up faster. MMMMMM I can see that BUT it still makes sense to have less

restrictions for over all efficiency and heat transrer.

I also wonder if he gets a better markup on Magnaflow than Banks.

Also are ther otherways to get a 4" turndown besides a Banks system . .

I found this truck on e-bay ... I hope it is as good as it seems in all the

checks I did

 

[LesStallings]

I recently change out my 3. 5" elbow and downpipe with an 4" elbow and downpipe from the later 600 model. Also, I replaced the 3. 5" section to the muffler with a 04. 5 cat delete pipe and installed the MBRP muffler.



Other than the change in sound (a good change), I really can't tell much difference in the way the truck runs (seat of the pants measurement). I THINK it is faster and I know it is much less restricted. EGTs should be lower, but it will be hard to know that since back to back tests towing are not practical.



It is very easy to get a low restriction, full 4" exhaust system for the 03-04 CTD. Reasonably inexpensive too. PM tomeygun for a great deal - a fraction of what a Banks system cost and the same, if not better performance.

 

[EFickbohm]

Les... I have a 03 with a banks which works fine, but i am trying to

understand the logic with what saltlake guy said . When you dino a truck

is the power mesured on exceleration? If that is the case it would make sence .

a restriction would posably creat a higher flow speed thus the turbo would spool

up faster ie more inital power. (a nozzle on a garden hose,water moves faster but less water gpm leaves the hose) BUT I also would think at sustained speeds

crusing say 75 mph the restriction created by the down pipe would require

energy and also cause heat buildup higher egt... .

Are ther other options for a 4" pipe that hookes up directly to the turbo??

On my 03 one of the biggest benefits is drivability the faster spoolup

makes downshifting sooo eazzy and Funn

We are getting this 04 becaus it has 4x4. I am going to be selling the 03 2x It has been

a great truck

 

[JCleary]

The theory is that with a 4" elbow and downpipe, the turbo will spool faster than stock. The ECM sees boost raise too quickly, and will defuel the truck to bring boost back in check.



I am not sure if this theory is true or not, but I did lose some mileage when installing the AFE intake and Banks exhaust.



The only loss in hp will happen when your motor is swinging up to full boost, 24-25 psi or so. Once you're at max boost, the new exhaust will be more efficient, giving you better performance and lower egt's. How much, I do not know.



The opening on the exhaust side of our puny turbos is so small I don't think the 4" makes a huge difference. If you have a cat, however, I think removing it would provide beneficial results.

 

[LesStallings]

I would think the boost elbow that comes with the 04 EZ takes care of the ECM boost fooling. The power seems to come on the same as before, which is basically at 1,700 RPM.