3” vs 2.5” exhaust for 1HDT. Does it really make a difference? (2 Viewers)

[bug616]

I need a new exhaust and can get a full 304 stainless exhaust in 2.5” for half the price of the same in 3”.

My motor is currently stock but I will soon be adding an intercooler and lightly tuning the pump for the best balance of power and reliability I can get out of the stock turbo. Probably around the 14-15psi mark.

My question is whether the 3” is needed for what I want - would it really make an appreciable difference? Or, will the 2.5” at half the cost be plenty good enough?

The default recommendation everywhere I look appears to be 3” but I haven't found a single reason or data point as to why!

 

[Gimme a 60]

Here is the way I see it.

Engines are just big air pumps - they take take in air, and expel the same amount of air.

More air in = more air out.

If you aren’t putting in more air (turbo), it’s probably fine. However in some cases like my BJ60 adding another 1/2 in of exhaust diameter may be beneficial to low hoarse power engines.

It’s up to you.

 

[cruiserpilot]

Just order this. Direct bolt in 3” with 3” dump. That engine will breath much better and
future options of any kind are possible without extra costs and hassle. I doubt you’ll find
this cost stateside even with shipping added.

Toyota - 80 Series - 80 Series 4.2L 1HD-T - Factory Direct 4x4 Exhausts

www.factorydirect4x4exhausts.com.au

 

[Dilspec]

Here is the way I see it.

Engines are just big air pumps - they take take in air, and expel the same amount of air.

More air in = more air out.

If you aren’t putting in more air (turbo), it’s probably fine. However in some cases like my BJ60 adding another 1/2 in of exhaust diameter may be beneficial to low hoarse power engines.

It’s up to you.

This and you may see slightly lower EGTs.

 

[SNLC]

It won’t hurt to run a 3” but without going to an upgraded turbo and more boost in my opinion without more boost ect-all you won’t see a big difference between the two sizes.

Cheers

 

[mudgudgeon]

You could ask the same question about intercooler and tuning.
An intercooler will have minimal benefits below 14psi. There's some benefit, but not heaps.

On my two diesel cruisers, i installed 4" dump pipe going into 3" exhaust from the transfer case back. My reasoning was that oversizing the dump pipe meant zero restriction, and faster initial spool up from the turbo.
The performance change certainly seemed to suggest my thoughts were valid. No doubt unnecessary and overkill, but for me it was s fun experiment.

Free flowing exhaust, intake, tuning, more boost and intercooler are the keys to improving performance and efficiency. I personally think exhaust upgrade on the stock engine and turbo is the single biggest improvement you'll make to unlock some power. That along with pump tune and boost increase to about 15psi, but exhaust is the key.

So maybe the question is, will you get a taste, and want more? If yes, than is the saving worth it if you decide 2.5" wasn't enough

 

[bug616]

Just order this. Direct bolt in 3” with 3” dump. That engine will breath much better and
future options of any kind are possible without extra costs and hassle. I doubt you’ll find
this cost stateside even with shipping added.

Toyota - 80 Series - 80 Series 4.2L 1HD-T - Factory Direct 4x4 Exhausts

www.factorydirect4x4exhausts.com.au

To get that shipped to the U.K. would make it the most expensive option and for a lower grade of stainless

 

[Shyrock]

Just order this. Direct bolt in 3” with 3” dump. That engine will breath much better and
future options of any kind are possible without extra costs and hassle. I doubt you’ll find
this cost stateside even with shipping added.

Toyota - 80 Series - 80 Series 4.2L 1HD-T - Factory Direct 4x4 Exhausts

www.factorydirect4x4exhausts.com.au

How about this one? Anyone have experience with this company?
Toyota Landcruiser 80 Series (1990-1998) 4.2L 1HDT & 1HDFT 3 - https://ppdperformance.com.au/collections/landcruiser-1990-1998/products/toyota-landcruiser-80-series-1hdt-1hdft-stainless-exhaust-system

 

[cruiserpilot]

I’d never heard of ppd performance. I have a couple of guys here in Canada with the factory4x4
exhausts and they are very happy with them. Custom exhausts here now run $1800 and they are
not the same quality. As far as shipping to the UK, that’s a difference for sure.

 

[AussieHJCruza]

How about this one? Anyone have experience with this company?
Toyota Landcruiser 80 Series (1990-1998) 4.2L 1HDT & 1HDFT 3 - https://ppdperformance.com.au/collections/landcruiser-1990-1998/products/toyota-landcruiser-80-series-1hdt-1hdft-stainless-exhaust-system

PPD are a good budget exhaust, made overseas. You should expect to have to wrestle it a bit to fit properly.

 

[Sonofaskipper]

^ this.

 

[veiloctane]

I have the redback in stainless steel 3" with muffler

Redback 4x4 Extreme Duty Exhaust for Toyota Landcruiser 80 Series 4.2L 1HD-T/FT (01/1990 - 02/1998)

Redback Extreme Duty Exhaust to suit Toyota Landcruiser 80 Series Wagon. Suits Vehicles with 1HD-T/1HD-FT or CT26 Style Turbo. This exhaust system routes inside the chassis rail. Product Specifications: 3" Turbo Back Exhaust Available Sound Options include 8" Round Straight Through Muffler...

peconline.com.au

its been a huge upgrade. egts cool so fast

 

[logicbyondreaso]

I have the redback in stainless steel 3" with muffler

Redback 4x4 Extreme Duty Exhaust for Toyota Landcruiser 80 Series 4.2L 1HD-T/FT (01/1990 - 02/1998)

Redback Extreme Duty Exhaust to suit Toyota Landcruiser 80 Series Wagon. Suits Vehicles with 1HD-T/1HD-FT or CT26 Style Turbo. This exhaust system routes inside the chassis rail. Product Specifications: 3" Turbo Back Exhaust Available Sound Options include 8" Round Straight Through Muffler...

peconline.com.au

its been a huge upgrade. egts cool so fast

Does the inside frame rail run need any additional mounting points since the factory outside frame mount is not used?
Could you take some photos of your setup?