1HZ intercooler thread (1 Viewer)

[lshobie]

Hi Guys, now that I have figured out what turbo I am going to use I need some help with the intercooler.

I will be using a front mount as there is lots of room between the grill and the a/c condensor/rad.

Now I see on Garrett's site that they have a chart of intercoolers based on HP rating - there is no way it can be that simple - or can it be? The bottom line is that I need something big enough to do the trick, but not to big as to take up too much space - or to not be useful.

Here is garret's link:

http://www.turbobygarrett.com/turbobygarrett/catelog/Intercoolers/Intercoolers.htm

So, how do I determine what size of intercooler I need?

 

[Dougal]

The best intercooler is simple.
It's the biggest one you can fit in the space available.

From there you moderate it down to best bang for the buck or best bang for the space and work involved.

HP ratings for forced induction are usually based off petrol engines at the rough rate of 10hp = 1 lb/min of airflow.
For diesels you shift a lot more air, for example a T25 turbo is rated for around "250hp", yet will probably only feed a 130hp diesel.

 

[Entaran]

The best intercooler is simple.
It's the biggest one you can fit in the space available.

From there you moderate it down to best bang for the buck or best bang for the space and work involved.

I call BS.

Intercooler sizing is best achieved by running close to the "rating" on the cooler. Running 3 inch in/out on a cooler will create SIGNIFICANT "lag" increases but better "top end". The best cooler for a diesel will have approx 2 inch inlet and 2-2.5 inch outlet and the piping to match.

If you -really- want a cooler, goto www.are.com.au

You can get decent ones off ebay too, but there isn't much in the market (globally) that stacks up to an ARE cooler.

If you want your cooler sized for you by a professional, email them. I've gone from a "600x300" ebay special (biggest one I could fit) on my roadcar which was approx 260kw @ wheels, changing to an ARE cooler that was specifically sized for my application (using 2 inch inlet and 2.5 inch outlet, instead of 3" in/out) I registered 10psi of boost 750 rpm EARLIER with the new cooler and a new peak power figure of 288kw @ wheels. This is on my turbo 4cylinder road car.

Sizing an intercooler however is NOWHERE NEAR as complicated as sizing a turbo. It really is simple. Keep the inlet/outlet sizes down to ideally the outlet of the compressor housing of the turbo (or 2 inch, whichever is bigger) and the "cold" side of the cooler (to inlet manifold) of approx 2.5 inches. or 2, your choice. Unless you're pushing 30+psi of boost Which I highly doubt.

 

[Dougal]

I call BS.

Intercooler sizing is best achieved by running close to the "rating" on the cooler. Running 3 inch in/out on a cooler will create SIGNIFICANT "lag" increases but better "top end". The best cooler for a diesel will have approx 2 inch inlet and 2-2.5 inch outlet and the piping to match.

Do you have anything to back up the "significant lag"?

IMO it's an urban legend. The intercooler piping is already full of air, extra air in = extra air out. Your turbo can pump the volume required in a fraction of a second.

I do agree that there is a big difference between a good intercooler and a bad one. But from there, bigger will always work better.

 

[Japan4X4]

Do you have anything to back up the "significant lag"?

IMO it's an urban legend. The intercooler piping is already full of air, extra air in = extra air out. Your turbo can pump the volume required in a fraction of a second.

I do agree that there is a big difference between a good intercooler and a bad one. But from there, bigger will always work better.

Air is composed of a mixture of gases. Gases are compressible.

 

[Dougal]

Air is composed of a mixture of gases. Gases are compressible.

Good thing too. Otherwise your turbo wouldn't work and your conrods would bend.

 

[VTCruiser]

intercooler shape is important too. having the end tanks along the longer edges will reduce the pressure drop across the IC. So effectively you want a "wider" IC with more tubes over a "longer" IC.

Wide:

VS

Long:

 

[lshobie]

That's some good info - thanks guys.

 

[Entaran]

Do you have anything to back up the "significant lag"?

IMO it's an urban legend. The intercooler piping is already full of air, extra air in = extra air out. Your turbo can pump the volume required in a fraction of a second.

I do agree that there is a big difference between a good intercooler and a bad one. But from there, bigger will always work better.

If you still think it's an urban legend then you haven't done any testing. Read the 2ndlast paragraph of my post.

It's a basic physics principle that you need more air to fill a larger pipe.

 

[Tapage]

Interesting read ..

http://www.are.com.au/feat/techtalk/intecoolersMR.htm

 

[Dougal]

If you still think it's an urban legend then you haven't done any testing. Read the 2ndlast paragraph of my post.

I have read your post. You installed a better intercooler which gave a better result. Is there something else hidden there?

It's a basic physics principle that you need more air to fill a larger pipe.

The pipes are already filled with air (remember this is a diesel, not a throttled petrol), if you put a 1psi pulse in the front, you'll get a 1psi pulse out the end pipe. That pressure wave will travel at approx 330 m/s (that's pretty quick). The time it takes to get in and out is not a problem.

There are plenty of very fast 1/4 mile times proving that a large intercooler and piping does not result in lots of lag.

 

[Entaran]

Drag racing has NOTHING AT ALL to do with driveability and DEFINATELY nothing to do with "down low" power or response. Drag cars almost invariably have a GT35/40 or larger strapped to them that makes power above 4500 rpm or similar (depending on displacement). Don't make the mistake of comparing a 1/4 mile time to a real world driveability scenario.

I went from 3 inch inlet piping to 2hot/2.5cold with a better cooler and got a massive increase. Also a huge decrease in spool time for the turbo and much more crisp response.

Regardless of petrol or diesel, there will still be the same form of benefits. The difference is a diesel is controlled by the injector pump/amount of fuel being injected rather than a throttlebody controlling the amount of air.

The pipe is indeed filled with air. At 0psi above base pressure. To pressurise the ducting to 13-15psi or whatever you're running boost wise will obviously take LONGER with larger pipes as the cross sectional area is much much larger. (A 3 inch pipe has more cross sectional area than TWO 2.25 inch pipes).

 

[Adam B]

Entaran,

One thing that keeps confusing me.....how come you suggest a larger pipe on the cold side of the IC? Since the air cools and becomes denser I'd think you could get by with smaller piping downstream of the IC.

 

[sandcruiser]

to make an analogy for what Entaran is saying:

Take your air compressor instead of a turbo
now attach a hose to the outlet. How long till you get 50psi at the hose? Not much time at all.

Now, put a 5gal tank between the outlet and the hose. It's going to take a little while until you get 50psi (or even 5, or 10) at the hose.

The intercooler, to some extent, acts like a tank. Bigger intercooler is likely to mean bigger lag. There's no way to avoid it. The question becomes: do you want a turbo/intercooler that spools up fast to boost you at low rpms? or do you want one that spools up a little slower and gives you cooler boost at high rpms?

I think. But I don't know much about these things, so if I'm wrong... feel free to educate me.

 

[Tapage]

or do you want one that spools up a little slower and gives you cooler boost at high rpms?

It's also close related to the rpm range and power band .. in a gasser you have 4k rpm of power band in my 2H I have 1.5k rpm ? or less ..

It's usual I start a slippery hill in 2nd .. and need to shift at mid of the hill .. I wanna less lag and quickly boost ..

 

[Dougal]

Drag racing has NOTHING AT ALL to do with driveability and DEFINATELY nothing to do with "down low" power or response. Drag cars almost invariably have a GT35/40 or larger strapped to them that makes power above 4500 rpm or similar (depending on displacement). Don't make the mistake of comparing a 1/4 mile time to a real world driveability scenario.

The purpose of the drag racing analogy was simple, to prove that big intercoolers don't provide big lag. If the "many seconds of lag" myth was true, then big intercoolers could not be used for any racing which involved rapid acceleration.

Low down power or response does not change with an intercooler, the turbo will only start to spool when sufficient exhaust energy (temp and flow) is thrown into it by the engine. The intercooler cannot improve on that.
Until you've reached about 10psi and the turbo is fully spooled, the intercooler does nothing useful.

I went from 3 inch inlet piping to 2hot/2.5cold with a better cooler and got a massive increase. Also a huge decrease in spool time for the turbo and much more crisp response.

As asked by Adam, why have you done that?
The air into the intercooler is less dense and requires the bigger pipe if you want to even out flow restrictions

How can reducing the internal volume of your piping by only 1/3 give a massive difference in spool time?

The pipe is indeed filled with air. At 0psi above base pressure. To pressurise the ducting to 13-15psi or whatever you're running boost wise will obviously take LONGER with larger pipes as the cross sectional area is much much larger. (A 3 inch pipe has more cross sectional area than TWO 2.25 inch pipes).

Of course it'll take longer. But I say it'll take a tiny fraction of a second. Those who think it takes whole seconds haven't thought it through.
We are not filling an empty vessel, we are increasing the pressure in one end while the engine is sucking on the other.

Stage 1.
No boost, turbo is iding, boost is zero, engine is spinning above the rpm threshold that the turbo can provide boost at.

Stage 2.
Pedal is floored, more fuel is dumped into the engine.
Exhaust gets hotter, so volume flow increases, turbo compressor puts a 1psi pulse into the intake plumbing.

Stage 3.
That pressure wave travels at the speed of sound (330 m/s) through the plumbing, intercooler and into the engine. Engine mass flow increases, turbo spools harder.

Stage 4. Repeat stage 2, but pressure increases to 2 psi.

Stage 5. Repeat until a wastegate opens limiting boost pressure or fuel loading is reduced.

 

[Dougal]

The question becomes: do you want a turbo/intercooler that spools up fast to boost you at low rpms? or do you want one that spools up a little slower and gives you cooler boost at high rpms?

The intercooler doesn't change the rpm when a turbo comes to life.
It can however lower the rpm required to get maximum boost.

 

[jasonmt]

Interesting read ..

http://www.are.com.au/feat/techtalk/intecoolersMR.htm

Given the web page linked by Tapage I would have to say that Entaran seems to have both practical experience and a source that could be considered informative on his side.

 

[Fromage]

Louis,

You have to remember what you are after.

This is not a race car. This is a diesel. I personally don't think that the infinitesimal amount of turbo lag caused by an oversize intercooler (<1 second) is going to prove noticeable while driving. We are dealing with a cubic foot of increased volume. I also know that you would be stupid to spend more than 200$ on an intercooler on an off-road truck in Canada. Sure, Spearco cores are better than the cheap chinese intercoolers from an efficiency standpoint, but boy are you going to cry when you catch a rock/branch and puncture one of the passages. Trust me, I know.

My vote is for an 80$ ebay special intercooler, that fits nicely in the truck. As big as possible. It will will work OK at lower speeds and won't require the same air velocity to cool the same amount. You are only going to be running what, 10 - 12 lbs?

Didn't some guy in the 70 series section from AK already intercool a 13BT powered truck? Maybe he can provide a part number of a good fitting core.

BTW - I got your message, until my intercooler comes in (because the old one is punctured) I am out of commission. Don't I wish I had used a cheapo Ebay special.

 

[crushers]

sheesh guys, talk to someone tht KNOWS what he is talking about:
www.bellintercoolers.com
and talk to Gerhard.
he KNOWS his stuff and how to figure the proper sizing for both diesel and gassers.

and NO, Roverboy, bigger is NOT better.