1HD-T 3" exhaust downpipe / elbow (1 Viewer)

[Adam B]

Anyone who had gone to a 3" exhaust on their 1HD-T.....what did you use for a downpipe and turbo elbow?

There are plenty available for the Supra 7M-GTE CT26 and I know I'll end up having to do a bunch of cutting and welding no matter what route I take.

I guess my other option is to cut the factory elbow off the flanges, bore out the flanges, and weld on a 3" 90 degree elbow. What a hassle.....

 

[crushers]

and why do you want to do this?

 

[Adam B]

Wayne,

I intend to go to a 3" exhaust all the way through. I haven't removed the factory elbow to have a look yet but I assumed that it was fairly restrictive, since the ones they mated to the other CT26s were. I was even considering a 4" elbow and then 3" downpipe, flex joint, muffler, etc. My understanding of turbo exhaust theory is that bigger = better, particularly when it comes to the elbow and downpipe.

Presently, the flange between my elbow and downpipe has 2.5" tube welded to it (aftermarket job done while the previous owner had it). From there out it's all 2.5" stainless mandrel bent. Nice job but I don't know why anyone would have bothered spending that money and not gone bigger.

 

[crushers]

Wayne,

I intend to go to a 3" exhaust all the way through.

Presently, the flange between my elbow and downpipe has 2.5" tube welded to it (aftermarket job done while the previous owner had it). From there out it's all 2.5" stainless mandrel bent. Nice job but I don't know why anyone would have bothered spending that money and not gone bigger.

probably cause there is no real advantage, 2 1/2" mandrel bent is perfect for turbo spool up, EGT and basic flow...
i suspect you want to increase your HP by the misconception that larger exhaust will flow better and increase this...as long as the exhaust is flowing freely then on a dyno larger exhaust does not increase HP or torque. i beleived the hype as well till i talked to a reputable turbo shop about larger exhaust.

if the exhaust you have now is free flowing then, in my opinion, leave it alone. if you want more HP then go with nitros or propane and of course an intercooler. what boost are you running now? what is your max EGT? how much black are you pouring out the exhaust pipe?
what works for gasser does not necessarily work for diesels...

 

[scuba steve]

black smoke

hey Wayne, i am wondering why you are reffering to how much black smoke is coming out the exhaust. i currently have a bit of smoke coming out my exhaust when i accelerate or even just start my truck in the morning or even if the engine is warm. is this good/bad, what should i be looking for etc...thanks Wayne

 

[Adam B]

Thanks for the responses.

Far as I know, my boost is unmodified but it measures 11.5psi. When boosting I do not have any visible smoke out the back. My max EGT is unknown because I always let off around 1300F. I could easily go beyond that. I have no problems on flat road or unloaded. It's when I have 800 pounds of gear and I'm trying to go up the big highway hills that I end up dropping to 80km/h because I have to let off the gas at 1300F....

My belief was that a larger exhaust, at least elbow and downpipe, allow the hot air to get out faster, resulting in lower temps. It's not that I don't have more power available, it's that I have to let off because my temps are too high.

Along with that, I made a manual boost controller that I'll throw in next weekend, bump it to 14psi, then do an intercooler, then maybe more boost.....we'll see.

 

[kup99]

Smoke in the morning should usually be blueish and a small puff of black smoke under hard acceleration is pretty much perfect as far i know!!

this is the way i understand it. I think

there is a screw you can adjust on the fuel pump that will allow more or less fuel (run richer or leaner). If it is tuned right you can gain a few more ponies too!!

Hope this helps

 

[diesel junkie]

Its important to know how far you want to go power wise because it gets spendy real quick, many here play with boost & fuel for some small gain which IMHO isnt wise long term.
Elbow after flange??
Anyway the factory system has some restriction & might as well go 3in at the same time but any bigger slows gasses too much as they cool and actually slows things up.
For me the big advantage (despite disputed power gains) is cooler turbo temps due to easier egress which translates into less heat soak & really no need for intercooling at stock boost (below 12psi).
Of coarse if you want silly power IMHO the 2valve 1hdt head will hold you back.

 

[Tapage]

http://4x4panama.com/foros/viewtopic.php?t=2299

 

[crushers]

Thanks for the responses.

Far as I know, my boost is unmodified but it measures 11.5psi. When boosting I do not have any visible smoke out the back. My max EGT is unknown because I always let off around 1300F. I could easily go beyond that. I have no problems on flat road or unloaded. It's when I have 800 pounds of gear and I'm trying to go up the big highway hills that I end up dropping to 80km/h because I have to let off the gas at 1300F....

My belief was that a larger exhaust, at least elbow and downpipe, allow the hot air to get out faster, resulting in lower temps. It's not that I don't have more power available, it's that I have to let off because my temps are too high.

Along with that, I made a manual boost controller that I'll throw in next weekend, bump it to 14psi, then do an intercooler, then maybe more boost.....we'll see.

1300F before or after turbo? after...ouch!!

yes, the larger exhaust = quicker purge of gasses.
increase of boost with no more fuel and it will run cooler as well.
increase boost to 14 lbs, back off fuel screw till you only have black under full throttle.
PROPER intercooler makes a world of difference... call a custom shop and get the dimensions for your engine and follow their advice. top mount = short runners but you will need a scoop.

cheers

 

[Adam B]

Who installs a pyrometer probe after the turbo?

I'm talking pre-turbo.

I'll try bumping up the boost to 14psi before I mess with anything else and see what I have to do with the fuel to match it.

Thanks very much for the advice.

 

[diesel junkie]

Only ever seen one top mount for the 80 that i could recomend (very spendy), generally at slow speeds they are more of an interheater.
I know of one installer that does safari installs that tried 3 different cheap chinese front mounts and lost power on the first two.
Another friend works at a 4wd shop & they dumped the front mount from a 1hdt due to parsitic loss at low boost levels.
Not saying intercoolers are a waste of time its just that for something that seems so simple there is a hell of a lot knowledge required to get it right.

 

[crushers]

hummm, i guess i got lucky then... the mapped top mount on the PZ rocks even off road...

i feel the biggest downside of the intercooler is most guys run to the nearest junkyard, find a used intercooler and "make" it work. same with turbo's, instead of figuring out what DOES work they grab something, bolt it on and then go...

talk to the shops that know what they are talking about and listen to them, it really does work.

the design of the hood scoop makes a work of difference as well, look for where the most air flow is, tapper the design from wider at the front to narrower where it feeds the intercooler and even at slow speeds you will recieve forced airflow through it, of course an intercooler is designed for higher boost levels which only come on under load (like chewing through mud under full throttle, not that i would ever do that)

as for higher boost, you are pushing more air into the same area with less fuel hence the lower EGTs resulting...

cheers

 

[brownbear]

I think if your hitting 1300 before your at WOT you need to back the fuel off. Your over fueling.

Spending a thousand bucks on 3" exhaust isn't going to solve that. Might lower it a little.

 

[diesel junkie]

The perception is more air less egt but this isnt always the case when pushing past stock settings (design parameters of the 1hdt ct26) can cause exhaust gasses to backup from the turbo into the engine causing elevated temps.
Undersized compressor wheel has a habbit of tossing tips when pushed past stock settings.

 

[BlueHZT60]

On my HZ-60 I've got a straight 3" exhaust, no restrictions, except the tailpipe I squished. My EGT's won't go over about 1150 - post turbo, boost at 9lbs. Yes, I also slow down on the big hills. My intake air - top tube - gets as hot as 165f, but at same time radiator fluid is getting into the 190-195 range. This is in 75-85 degree ambiant air temp weather. Rarely do I have any visible exhaust.

What about turn fuel down a small bit, clear out front airflow (lights, winch controller), oil cooler?, propane? liquid-Air intercooler?

Bob

 

[tlcruiserman]

Anyone who had gone to a 3" exhaust on their 1HD-T.....what did you use for a downpipe and turbo elbow?

There are plenty available for the Supra 7M-GTE CT26 and I know I'll end up having to do a bunch of cutting and welding no matter what route I take.

I guess my other option is to cut the factory elbow off the flanges, bore out the flanges, and weld on a 3" 90 degree elbow. What a hassle.....

Here are some pics of 3" exhaust on 1994 Diesel Conversion with 1HD-T.

http://www.westcoastcruisers.com/93HDJ80CV.htm

Cheers,

Michael

 

[Tapage]

Pretty nice exhaust setup ..