12h-t exhaust upgrades (1 Viewer)

[Quat]

Hello,

Been doing a little research on larger diameter exhaust for the 12h-t, it looks like most people add boost along with upgrading the exhaust.

Does anyone have any input on whether just upgrading the pipe diameter to 2.5 or 3" is worth it without adding boost? Does it lower low end torque?

and perhaps the same for adding an intercooler, or larger exhaust + intercooler.

Thanks

 

[Crick60]

It all depends on how much you want to open your wallet...

IMO 3" is just an increase in decibels and would necessitate boost increase to maintain a sensible back pressure.
2.5" is ample with a triflow or similar.

Intercooler is a great idea but again has an exponential relationship with your wallet.

All said and done my question with any engine and especially the 12ht is why???? The motor is near flawless with ample power and is the apogee of reliability, why would you want to mess with that?

 

[Quat]

At the moment I'm not worrying too much about wallet, just what could be had.

Keeping it reliable and plugging along without issue for a long time are very important to me, that is why I'm not interested in increasing the boost. A little fatter exhaust pipe and an intercooler seemed like mods that might add a little without any affect on reliability.

As to the why, lot of steep hills on the freeway at 5-10,000 feet elevation around here and it can get up over 110F in the summer. Just wondering if it might pull a little better with 3 people, 2 dogs and gear or for a trailer once in a while.

 

[IanB]

Larger exhaust will lower your EGT's, which I would argue will only increase long term reliability, but does little to help performance without raising the boost level (in my experience). Same story with the intercooler, but it's not really necessary at stock boost levels as you're not introducing any extra heat to the charge air over stock.

 

[Hulsty]

It all depends on how much you want to open your wallet...

IMO 3" is just an increase in decibels and would necessitate boost increase to maintain a sensible back pressure.

No wrong, 3'' can be as quiet as you want with the right mufffler, back pressure? wrong, you want all those gasses gone as quick as possible, back pressure is in the exhaust manifold created by the turbo and just reduces power.

 

[Crick60]

No wrong, 3'' can be as quiet as you want with the right mufffler, back pressure? wrong, you want all those gasses gone as quick as possible, back pressure is in the exhaust manifold created by the turbo and just reduces power.

Yeah I'd reconsider the information you have available to you or speak with a diesel professional.

3" won't hurt but it needs to be matched with a proper muffler and dump pipe and it WILL be louder without discrimination and you WILL suffer back pressure losses which WILL be inefficient if not addressed with boost compensation and matched muffler.

 

[Crick60]

Yeah I'd reconsider the information you have available to you or speak with a diesel professional.

3" won't hurt but it needs to be matched with a proper muffler and dump pipe and it WILL be louder without discrimination and you WILL suffer back pressure losses which WILL be inefficient if not addressed with boost compensation and matched muffler.

I want to retract most of my statement/misguided commentary, I concede that to a point minimising back pressure is most beneficial especially in regards to expelling gases and effects on temperature but it is important to note that some degree of back pressure is required to be retained to maintain low end torque, boost compensation is not necessary and most people would up the boost because the larger exhaust allows them to because of the reduced temperature and back pressure.

 

[niffa]

Well said crick^ personally i have 3" mandrel with a genie straight thru. It was no louder than stock so i promptly removed the muffler all together. Top mount intercooler with a fan and running 14psi with half a turn of fuel. Not what id call extreme in the slightest but is well sufficient to pull my 3 ton trailer at 90kmph. Any faster and egts rise quickly.

 

[Quat]

Thanks,
So, wallet aside, there isn't much benefit to a 2.5" or 3" exhaust and intercooler without adding boost?

I suppose I should ask what 'not much' is: 5-10hp or ft/lbs or less?

 

[Hulsty]

A large exhaust makes minimal difference to peak power, benefit to peak power is reduced back pressure making everything run more efficiently. A larger exhaust and (I found on mine) 3'' dump pipe made a big difference in spool up and therefore torque delivery. Got on boost harder/faster so more torque earlier. From there with a EGT gauge I added more boost/fuel.

 

[Crick60]

What he said ^^^

Bigger exhaust will allow bigger boost with out back pressure and EGT troubles but you'll still have to consider increased engine wear and tear like blow by, turbo failure etc.

It may just be worth doing the timing, valve adjustment and dyno to see what power you have compared to standard before trying to add more power on top of a detune setup.

 

[Quat]

Thanks, thats a good idea.

I'm not really interested in increasing boost, just if there are some things which can be done to increase output without affecting wear and tear. Its a lot easier on something like a Ford.

Just kicking around ideas for upgrades. Main concern for "increasing" power is occasionally keeping up with 75mph traffic at 6-10,000 feet going up a steep hill. I have a 3rz which kind of struggles at that point at the moment.

 

[IanB]

Bumping up the boost a few psi will actually lower your EGT's as well, resulting in a safer tune. So long as you stay within the limits of your turbo, it shouldn't really affect longevity negatively, while giving you a bit more power when you need it. It's when you add more fuel that you have to watch things.

 

[Quat]

Hm, that is interesting.

The occasions I'd "need" more power would be pretty rare, so that might be worth looking into. Most of the time it'll be on the flat or off road.

Perhaps the first step should be tuning it, installing an EGT gauge and seeing how it does in the summer at altitude.