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Hilux exhaust questions?

General Tech Talk

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Hilux exhaust questions?

Post by dan_2818 »

Ive got a 2.8 diesel hilux with a mitsubishi turbo on it, running into a two and a quarter inch dump pipe then into the stock exhaust. Running 8 pound.

im planning on building a larger exhaust for it by buying a lenght of pipe and some bends and welding it all together having it finish at the rear of the cab.

What size tube should i use?
Is this dump pipe large enough?
And should i go straight through or have the smallest exhaust legal?

Cheers, Dan
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Post by Barno111 »

3inch exhaust, have as less bends as possible, i would upgrade to a 3inch dump pipe as well!
1996 HZJ75RP, DTS turbo with 3inch exhaust, rear locker, MTZs, 2inch shackles, 2 inch custom packs!
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Post by RedRat »

Two and a quarter is what comes with the DTS (mitsubishi hairdryer) kit I fitted to my 2.8, so it is no doubt adequate.(the 2.8 is the limiting factor, not the exhaust). Having said that, I got an exhaust shop in Bundy to run a two and a half inch system with a couple mandrel bends and a 12 inch hotdog (no muffler) that dumps just behind the cab for only $140. Not very loud. I think you'd struggle to make it fit without a pipe bender. I believe I gained at least 1 or 2 hp with this mod, truly mindblowing.
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Post by berad »

Stock turbos and there accessories may be adequate, but far from optimum.

Stock turbos and everything that makes them work is a compromise in all aspects, they cant put a fuel guzzling setup on it, nor can they put a noisy turbo spooling monster, they no doubt spend millions on research but... they have such a wide range of customers and driving conditions to cater for.

Was the 1-2hp a seat of the pants dyno?, what was tested.



exhaust temps
torque
response
efficiency
boost efficiency.

Did you replace the dump pipe, if not i would expect little or no gain at all, you didn't remove the stock restriction, my previous cars have had split dump pipes, main pipe for rear turbo wheel, smaller diameter pipe for the wastegate which joins in further down the pipe to allow better flow when they both meet into the lower part of the dump


Image


It shouldnt matter what motor it is, 2.8 or not, power and torque curves should improve/move in relevance to engine displacement with any air flow improvement, wheather it be intake or exhaust. If it doesn't something else is restricting it in one way or another.

My 2cents....

I'd put a 2.5 or 3inch full system in, from the rear housing of the turbo to wherever you decide to stop it, to big a diameter of pipe or the exhaust not long enough it will not improve, there is a fine line, its been discussed in detail on here and every forum known to man a million times.
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Post by coxy321 »

I'd go 2.5" from the dump back. DIY, but a length of pipe from wherever, and use mandrel bent sections (dont try bending pipe yourself). You can run straight through and it will still be very quiet (the actual turbo cut a phenominal amount of sound), the only noise issue might be of the turbo whistle - personally i dont like it. I currently run a big double pass muffler as my patrol is N/A at the moment, but i will swap it for a hotdog after the turbo goes on.
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Post by phippsy »

I made a 2 1/2" system from the dump pipe back when I fitted a turbo to my old lux. 1 length of aluminised steel and 2 maybe 3 90* mandrell bends and 2 or 3 flanges.
Was able to make it tuck up nice and high with flanges where I wanted them to make removal etc easier. All up cost about $200, but it was a few years ago so my memory is a bit hazy at best. No muffler, had a bit of a farty exhaust note to it, but from inside it was alright sop I never bothered with fitting a muffler.

All up took an afternoon to make and fit.
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