Intercooler Tech

[Screwy]

Gday,

Just a question for those Turbo diesel Gurus out there....

I have a DTS Turbo after market system on my TD42 patrol.

I am in the process of intercooling at present.

I have a front mount intercooler for it and its an air to air type.

My turbo has a 2 inch ( possible 2/1/4 ) outlet on it.

When intercooling it, do i need to stick to this 2 inch size on the turbo then through the intercooler and out to the manfold or can i upsize it no worries to a 3 inch with a silicone reducer and run 3 inch piping on both sides of the intercooler?

Also with regards to this, does length of piping play a major role in interooling a turbo diesel?
Id like to run piping a certain way which makes my piping on both sides of the intercooler quite long...... or does pipe length of magnetude make little difference...

cheers for any advice,

Screwy

[mickyd555]

TD05 turbo is 2" outlet. I ran 2.5" pipe but wish i had of run 2.25". The shorter the pipe the better i believe as it keeps the boost up and keeps the lag short.

[Red Dog 4x4]

I would run 2" on the hot side and 3'' on the cold side. All the ones i have built this is how i set them up and thay seam to work ok.

I am building a Air to Water atm with 2'' 45deg off the turbo to a 90deg 2'' to 3" bend going into the core so far it seams to work still waiting on the rad for the front. will get some pics soon.

Red dog

[Dzltec]

look at the turbobygarrett website. There are tech articles on pipe sizing, which is important to maintain air speed.


Andy

[love ke70]

as andy said, air speed is important, but also, the more pipework your running, and the more volume you have in the pipework the more lag you will have.
whether you will notice the difference or not is another question, but i think off the line and on spool up it would be quite noticable...

[anzac]

Keep your piping smaller. 3" on the intercooler is ok, but massive pipes means more space to pressurise and slower air speed = less responsive

[Screwy]

ok so possibly use the largest intercooler i can fit ( which i have and it has 3 inch on both sides ) and maybe run 2.5 inch on both sides of the cooler to the turbo and manifold then?

cheers

[V8Patrol]

From my experiance......

the actual turbo outlet size +1/4 inch bigger (max) is the go for the connection from turbo to I/C

I/C to throttlebody is the same rule of thumb ..... +1/4 inch bigger (max) than the size of the throttlebody

the turbo and throttleody are the 2 determining factors on pipe size as they are the 2 areas of restriction when it comes to flow.

You know from your trade as to how liquid/gas creates cooling, basic same principle applies to turbos go too big and the natural cooling effect is lost placing all the cooling onto the I/C..... & yes even I/C size has an effect, we both know its air speed thats the issue, too slow and it has time to cool but places more heat into the cooler which then takes longer to disipate ..... too fast and although we utilise the natural cooling effect we loose the actual I/C's cooling abilities.


Pipeing and I/C size is best matched to the turbo/throttlebody sizes.... too big or too small means horses bolting out the wrong gate


Kingy

[KiwiBacon]

You know from your trade as to how liquid/gas creates cooling, basic same principle applies to turbos go too big and the natural cooling effect is lost placing all the cooling onto the I/C..... & yes even I/C size has an effect, we both know its air speed thats the issue, too slow and it has time to cool but places more heat into the cooler which then takes longer to disipate ..... too fast and although we utilise the natural cooling effect we loose the actual I/C's cooling abilities.

I'm struggling with that, can you explain it better?

You can't make air travel too fast to cool.

[tweak'e]

You can't make air travel too fast to cool.

lamination effect. if the air is to fast some of it hugs the cooler while the rest goes straight through without touching the cooler, hence no heat gets transferred. usually the core generates turbulence to help combat that but if air speed is really fast you still get that effect.
also don't forget heat transfer takes time.
but in all honesty on a vehicle its more theoretical than practical unless you have a really crap designed IC.

[KiwiBacon]

You can't make air travel too fast to cool.

lamination effect. if the air is to fast some of it hugs the cooler while the rest goes straight through without touching the cooler, hence no heat gets transferred. usually the core generates turbulence to help combat that but if air speed is really fast you still get that effect.
also don't forget heat transfer takes time.
but in all honesty on a vehicle its more theoretical than practical unless you have a really crap designed IC.

You've been listening to too many old wives.
Ever heard of Reynolds number? The faster fluid travels, the more turbulent it is, the smaller laminar boundary layers get and the more heat transfer you get.

Otherwise we could get a really high pressure hose (so the water travels really fast) and hose you down and you wouldn't feel cold at all.

[tweak'e]

bad choice of words on my part there.

isn't Reynolds number more to do with flow in a pipe rather than a complex shape?
high speed air (or water from your hose) doesn't like to do sharp turns. in an IC it tries to go straight ahead rather than spread evenly before going through the core. you end up with high pressure where it goes in and low pressure on the sides ie dead space that really doesn't do much. tend to crudely call that laminar flow where you have the main flow down the centre and dead space with minimal flow around it. thats why you need decent designed end tanks so the air slows down and turns to spread along the tank before going through the core.

i get this more with computers. people fitting high speed case fans and wondering why their cooling has gotten worse. the air goes straight through and causes pockets of air in the case. if the air is slower it circulates the case better. they are not designed as well as an IC

[KiwiBacon]

bad choice of words on my part there.

isn't Reynolds number more to do with flow in a pipe rather than a complex shape?
high speed air (or water from your hose) doesn't like to do sharp turns. in an IC it tries to go straight ahead rather than spread evenly before going through the core. you end up with high pressure where it goes in and low pressure on the sides ie dead space that really doesn't do much. tend to crudely call that laminar flow where you have the main flow down the centre and dead space with minimal flow around it. thats why you need decent designed end tanks so the air slows down and turns to spread along the tank before going through the core.

i get this more with computers. people fitting high speed case fans and wondering why their cooling has gotten worse. the air goes straight through and causes pockets of air in the case. if the air is slower it circulates the case better. they are not designed as well as an IC

Reynolds number applies to all fluid flows. But the transition from laminar to turbulent flow will be different for each case. Inside pipes the transition is Re~2000.
Design of the end-tanks and connections is important for getting the flow close to even through all the cores, but even the worst intercooler will cool better than none. Pressure drop is another related matter.

The interesting thing about fans is the momentum they apply to the air is all wasted energy. The goal of a fan is to create a pressure difference and it's that pressure difference that drives the flow. Any speed you impart to individual pockets of air is lost energy to turbulent mixing.
This is why bigger and slower fans are a lot more effective than smaller ones. It's also why diffuser design (the scroll in a turbo compressor) is very important. Smoothly reducing the high speed flow from the impeller down to the exit flow speed is where a lot of efficiency is made or lost.

[Z()LTAN]

Dont let flashy forumlas and techical jargan get in the way of the truth.

With a diesel that is not so dependant on air speed, fit as bigger cooler as you can.

2.5-3" intake pipework you wont see a difference in boost increase speed between the 2 in a real world situation.

When all said and done, a good turbo coupled with a well tuned engine/fuel system will set your boost rise/spool speed reguardless of intercooler/intake design. - within reason ofcourse -

All i can say is dont make the intake restrictive even in the slightest.

Good luck

[80's_delirious]

Lag in a turbo deisel is far less of a problem then in a petrol, a turbo diesel under acceleration will be on boost most of the time from near idle right to the top end. I have read a few places that the intercooler and piping can act as a plenum (on a dlesel), so boost will not drop of completely between gears.
I found in my turbo diesel 80 series (no intercooler) that when I was up it for the rent, it stayed on boost between gears. boost would drop off from a peak of around 18psi to maybe 6-10psi between gears. I cant see any reason this wouldnt still be the case with an intercooler fitted.

[Screwy]

Dont let flashy forumlas and techical jargan get in the way of the truth.

With a diesel that is not so dependant on air speed, fit as bigger cooler as you can.

2.5-3" intake pipework you wont see a difference in boost increase speed between the 2 in a real world situation.

When all said and done, a good turbo coupled with a well tuned engine/fuel system will set your boost rise/spool speed reguardless of intercooler/intake design. - within reason ofcourse -

All i can say is dont make the intake restrictive even in the slightest.

Good luck

Sweet.

2 inch at the turbo up to 2.5, through the largest cooler i can get in there back to 2.5 into the inlet manifold....

can i run the pipeing nice and long or shorter the better?

cheers

[KiwiBacon]

can i run the pipeing nice and long or shorter the better?

cheers

The smoother the better.

[fester2au]

can i run the pipeing nice and long or shorter the better?

cheers

The smoother the better.

Exactly. Can't remember the figure but a 90degree bend equals a fair length of straight pipe as far as what it does to the flow of your system. Short and sharp is not the go compared to long and gentle but short and gentle is the ideal to aim for and compromise from there. Also if you can do it longer transitions from one size to the other is better, and more important coming back down. By that I mean the store bought reducers are not that great but fine if you don't have ability to make your own transitions.