New exhaust for my 12HT

[Dieseler]

If you go with a 2.5 exhaust without fatory mufflers and resonator you have eliminated any back pressure so going 3" is just a mute point and won't really benifit over the unrestricted 2.5 exhaust.
2.5 is good enough.

 

[monton]

Thanks... that helps me with my decision. My truck is scheduled to go in on Tuesday for new exhaust. 2.5" it is... cheaper!

 

[Tapage]

just for rereference .. with my straight 2.5" exhaust .. and plenty ( all that my IP can provide ) of diesel added my EGT are never a factor ..

Which it's not the case with my 1HD-T that have plenty of diesel too but 3" short straight pipe ..

 

[goldchaser]

let us know what its like after its done please montoon.

 

[Clint79]

If they say the best for the turbo diesel 4.5ltrs cruiser 7x series is a 3.5"
wouldnt a 4.0ltr turbo motor be better with a 3" than a 2.5?
maybe leave the 2.5" for the turbo diesel 4cyls hiluxs' etc?

 

[racingjason]

Not sure if I should be dredging up this old post or start a new one but here it goes. Like so many others, I am waffling on how to upgrade the exhaust on my 12HT. I went to the exhaust shop the other day and the guy thought it was really overkill to go with a 3" setup and recommended a 2.5" max. (He said my stock system was 2.25") I want to keep the truck as quiet as possible because it is used for long distance travel therefore I don't want to go the straight pipe route. The mandrel bent option adds 65% to the cost.

My thoughts were to go with a 3" press bent system and a muffler which may be equal to a 2.5" straight pipe system. Does this sound reasonable? (I can see myself only boosting it up to 10 psi or so.) More importantly, the exhaust guy said that he can not run 3" right off the dump pipe. Is this correct? Do I have step up from a 2.5 to a 3" from the dump pipe?

Thanks,
Jason

 

[Tapage]

I have 3" in my 1HD-T and it's loud .. the 2.5" that i have in my 2H-TI it's by far much more quiet ..

 

[Dieseler]

Measure the exhaust opening at the turbo flange calculate that and any larger wont make much difference.
Its like blowing through a straw then blowing through a 2" pipe then blowing into the air the later two there is no difference.

 

[Tim-HJ61]

A 3" steel pipe fits the outlet of the standard dump pipe.

3" is the recommended aftermarket install for a 12H-t - I've NO idea why any specialist would suggest any different. My exhaust fitter had no question about fitting a 3". See this link for the install.

Back pressure???? pfft. it's got a turbo. It needs to get RID of that air.

I have a resonator at the very back of the car in the same place as the standard installation and that is fine for me. It has a nice note going through tunnels with the sun roof open, but the drone is not present to any annoying levels. I also do long drives in the country, it is NOT a problem.

My installer did suggest a resonator only after checking me out and realising I'm the other side of 50 and having a noisy exhaust with a grey haired bloke driving it looks foolish, no matter the drivers own perception ;p

Once you install your 3" you can start to unleash the capacity within these engines as covered off here.

Just do it!

Tim

 

[Stone]

I have a 2.5" exhaust in my 12H-T converted FJ80. I didn't go mandrel bent because the shop I used didn't have one. THey had a newer bender that was very good at minimally deforming the bends...I'm pretty happy with the result, although it needed a lot of tweaking to making it work as the 12H-T was never meant to be in an 80.

I have a couple more bends than a 60 series would have, and even with no resonator or muffler, truck is fairly quiet...in terms of exhaust sound anyway...lol.

If I had a 61, I would definitely go 3" if the price difference between the 2.5" and 3" was reasonable. Be sure to install a good flex pipe as others have mentioned. It will save you a bunch of grief, and a decent stainless one only cost me $55.

 

[racingjason]

Thanks guys, this is exactly the type of information I am looking for.

Tim, did you need to buy a new flange to connect the 3" exhaust pipe to the dump pipe or does the stock flange work with the bigger pipe?

 

[350cruiser]

3'' pipe

i made a new exhaust system for my 60 with 12ht in it, i removed the stock cast iron dump pipe and made my own flange and blended a 3'' pipe onto it.
i brought all the bends and pipes from an exhaust supplier and welded it all up myself, it runs down the inside of the chassis rails and follows the path of the original pipe, goe's between the chassis and pto and exits just after the rear wheel. it has only one muffler in the system and is quieter than factory.
the results are just awesome and glad i went to 3'', it holds gears longer, has better fuel economy and there is no droaning or vibration

 

[LZ_Pan]

got my new exhaust installed now. i went 3" all the way from the turbo straight pipe all the way back. got flexi joint installed as well it was just extra AU50. what i have noticed is that turbo will spool much faster now. it revs much easier and sounds just unbelievable. i am very happy with this mod and definitely recommend it to anyone with 12ht. cheers guys, pan.

 

[prado t]

Good glad you are happy.