My son's step dad has been an over the road truck driver for years. He was just telling my son that the sure way to lower egt's is to go with a dual exhaust system and twin turbo's.
What say you ??

 

I agree on the twins. You don't need duals. Just a 5" exhaust system. That's one of the benefits of twins is cooler egt's.

 

Now see if you had a Powerstroke then you could do twins (one turbo off each side) then You can do TRUE DUAL just kiddin...Dont even know if that will work.

 

Thats funny you are definitely a ford guy

 

Yes and no. What BigBlue said. I installed twins and my EGTs are controllable now.

You see, what happens is when you add fuel, you get, and need, more boost, to burn the fuel, and cool the EGTs. Once you get to a certain point, about 35 psi on a stock turbo, the turbo begins heating the air as it compresses, and this causes more heat when you were counting on the turbo to cool things down. The second turbo, which is larger, and has a different efficiency map, pushes more cool air into the engine.

The problem with just putting a bigger turbo on, is once you have that great big turbo on there you have to wait a while for it to spool, and all the while you are huffing loads of black smoke and your EGTs skyrocket. With the smaller turbo on there, you get the quick spool-up, and then the larger turbo helps get the cooler air in, if the smaller one is wastegated properly.

Duals, well that's the "no" part. Duals are just for looks and bragging rights(?). You are still piping everything through the turbo(s) and are limited to the outlet of the turbo. If your big turbo has a 5" outlet, then duals that have more area than that will not do you any good, performance-wise.
My big turbo has a 5" outlet and it's 5" all the way back.

Chris

 

 

Duals on a big rig do help knock down there EGTs. Ive heard as much as 250* vs. a single stack.

On a pick-up truck? NO change in EGTs, just twice as many pipes hanging out the back.

 

Plus twice the sound, twice the smoke, and twice the looks.

Stamey makes a very good point. Twins also make driveability much better because of the faster spooling.

 

duals on a big truck help because the exhaust is pretty small, and they often run mufflers...

a 5" pipe on our little engines is pretty huge, so no need to split it...

 

downpipe 4" or bigger to reduce egt's and the rest at least as big. I have 4-1/2" downpipe and 5-1/2" stacks and it works great! leaves also enough room for nitrous/water-meth./propane use. I have a crankcase scavengetube behind the big turbo in the downpipe that works great this way, due to the reduced backpressure. the negative crankcase pressure helps in speeding up and building HP, and on it goes...

 

Maybe yes and maybe no:

Faster than a really big single...ie. HX-55, Full B-1, Sled Puller 66.

But twins are slower spooling than their smallest member would be alone. They are also slower than some of the newer Mid range singles....KSB-1,HTB2 (12 cm and maybe even 14 cm housing). With bigger than stock injectors, My KSB-1 spools faster than a stock HX-35. From all I've read the HTB2 is that fast also...or even faster.

I see no need for twins under 500 HP with the newest generation of singles! One exception I can imagine is towing heavy in the mountains. Than you just have to shift your focus from you EGT's to your H2O temps.

Back to original question-Twins will definately lower EGT's....Dual exhaust - doubtful on a CTD.

RJ

 

slower spooling than the small turbo alone, but you can also afford to run a smaller top turbo... I'm hoping my twins spool quicker than my hx40-16...

I'm either running an Hx35-12 or hx40-12 on top

 

good choice, I have the 12 housing of a 35 made for a 40 on the lathe. have now the 65mm exducerdiameter of the 40 in the 12 housing. and 59mm inducer on the compressorside. but with ext. WG.

 

if I find a cheap HX35-12, I'll just run that... otherwise, I'll just have a 12cm housing cut for my HX40. my twins are built with an external wastegate, so I should be fine. glad to hear it's workin' well for you

Forrest