Intercooler 3B/ Turbo Project......

[Dougal]

Here's some calculations Chris did to help select the proper sized IC


The head and lots of other stuff are back on. Fenders and days and days of plumbing are next.
pics to follow.

He's sized the intercooler by airflow through it. Rather than cooling capacity and outlet temperature.
For cooling, bigger is better.

BTW the time calculated has been based on the time to fill a completely empty intercooler and pipes based on the expected flow-rate.
Many people (including myself) don't believe this is valid. The pipes are never empty, we are instead interested in how fast it will pressurise.
Pressure waves travel through air at the speed of sound. Which is pretty quick and gets faster when air is heated and compressed.

 

[MrMoMo]

If I could make one suggestion to aid in the longer life of your new fenders...

Get some isolation tape, and cover the steel surface that is in direct contact with the aluminum -or vice versa (even when it's painted). Steel in direct contact with aluminum will set up a corrosion cell (battery) when you get salt water involved (winter driving, or spring on roads that were salted all winter, in the rain)

It's a very cheap step to include, and will make your aluminum last for ever...

I work for an aluminum boat builder, so I battle this stuff every day. If you want a better understanding of the phenomenon, there is a quick little explanation that applies to vehicles here;

http://trailer-bodybuilders.com/mag/trucks_deal_dissimilar_metals/

Great to see the inside of a 3B that has been running that far on a 2-tank veggie system, veggie was the 2nd best change I made to my truck.... Best? The turbo! You're going to love it!

 

[magnus_heydoc]

Dougal,
I do not believe that the trade off of more cooling (how much more exactly?), is worth the pressure drop that comes from a bigger IC. My turbo is maxed out as the waste gate is disconnected and permanently shut. In this case as with many others a bigger IC is not necessarily better. The appropriate size is more important in my and many other peoples opinion.
We'll have to agree to disagree.
aaron

 

[Chris Wilcox]

Really the calculations are the best available to us without an exceeding amount of effort learning a new topic. They were more to determine if the cooler core internal cross section was reasonable and whether we should get the 2" thick one or the 3" thick and go to the extra effort of modifying more structure and auxillary parts to get the rad moved back the required 2.5" for the 3" core. It seemed best to get the 3" core and buy a readily available 3"x12" ebay intercooler that happened to be the same core length as the width of the rad core. Also intercooler tubing packaging was a big factor and this particular intercooler was a great fit for this truck. Significantly more work would be required to fit a bigger core which was not in the scope of this installation.
For us this is a hobby and the calculations should not be taken as the authority on the subject, just an application of the basics found in Bell's "Maximum Boost".
Tube size and lag were only calculated out of curiosity to see if the tube sizes Aaron had on hand were in the ballpark, which they seem to be.
Anyway great discussions and I'm sure Aaron will let you know how it all works.
Chris

 

[Dougal]

Dougal,
I do not believe that the trade off of more cooling (how much more exactly?), is worth the pressure drop that comes from a bigger IC. My turbo is maxed out as the waste gate is disconnected and permanently shut. In this case as with many others a bigger IC is not necessarily better. The appropriate size is more important in my and many other peoples opinion.
We'll have to agree to disagree.
aaron

You've got that backwards. A bigger cooler has less pressure drop.

Clamping the wastegate shut can result in the turbine hitting choke flow and spiking exhaust manifold pressures. This kills performance at higher rpm.

 

[Dougal]

Really the calculations are the best available to us without an exceeding amount of effort learning a new topic. They were more to determine if the cooler core internal cross section was reasonable and whether we should get the 2" thick one or the 3" thick and go to the extra effort of modifying more structure and auxillary parts to get the rad moved back the required 2.5" for the 3" core. It seemed best to get the 3" core and buy a readily available 3"x12" ebay intercooler that happened to be the same core length as the width of the rad core. Also intercooler tubing packaging was a big factor and this particular intercooler was a great fit for this truck. Significantly more work would be required to fit a bigger core which was not in the scope of this installation.
For us this is a hobby and the calculations should not be taken as the authority on the subject, just an application of the basics found in Bell's "Maximum Boost".
Tube size and lag were only calculated out of curiosity to see if the tube sizes Aaron had on hand were in the ballpark, which they seem to be.
Anyway great discussions and I'm sure Aaron will let you know how it all works.
Chris

Thicker cores don't offer much extra cooling as the extra thickness gets warm air flowing over it. It is far better to go for the largest frontal area and only increase thickness if you are struggling for flow and experiencing large pressure drops across the intercooler.

 

[TheBigBoy]

You've got that backwards. A bigger cooler has less pressure drop.

Clamping the wastegate shut can result in the turbine hitting choke flow and spiking exhaust manifold pressures. This kills performance at higher rpm.

Right on both accounts. The pressure drop comes from flow restriction. And the turbo will be performing terribly with and achieving choke flow.

 

[gerg]

I tried out a 4 inch core and I can tell you it is extremely tuff to get air flow through it. 3 inch was much better. I would go for a 2 inch, but you would need a big core not to get some presure drop.

All this buisness of "sizing" cores is for quarter mile performance and the like. Its about how fast you can pressurize a core while trading off effeciency. For steady state, bigger is better. Im talking frontal area and not thickness btw.

 

[Chris Wilcox]

I agree that bigger and thinner is better. Having never done this before we needed some way to estimate if it was worth it or not installing the intercooler that we were able to find that packaged well in all regards and was inexpensive. That drove most of the decision frankly. It will either work or it won't but I'm guessing it will work good enough for this truck. We are not drag racing or looking for ultimate HP numbers.

 

[magnus_heydoc]

more pics.

Here are the latest pics, upsidedown bezel and all.
Fenders are painted and will go on next. Then hook up all the electrical and finish some water and fuel plumbing.
There was only one tiny spot left in the bay for my water overflow reservoir. Running grease with a two tank system requires a complete 2nd fuel system to the switching valves. That, a turbo, intercooler and original air can has left a packed engine bay.

 

[magnus_heydoc]

water resevoir

water overflow reservoir.

 

[magnus_heydoc]

Alright it's all back together and it works very well. My EGT gauge quit on me a year ago so it's tuned conservatively to a few turns of fuel giving 9lbs. of intercooled boost.
Is it possible that 9lbs. of cool boost actually produces more snort than 15lbs. of hot boost like it was before?
pics to follow.

 

[Dougal]

Alright it's all back together and it works very well. My EGT gauge quit on me a year ago so it's tuned conservatively to a few turns of fuel giving 9lbs. of intercooled boost.
Is it possible that 9lbs. of cool boost actually produces more snort than 15lbs. of hot boost like it was before?
pics to follow.

9psi intercooled is the same density as approx 14psi not intercooled.

 

[magnus_heydoc]

I'm curious, how do you compare the two densities accurately? A formula? Is there perhaps a chart somewhere?

 

[buschmaster86]

nice work !!

 

[magnus_heydoc]

finished pics

more pics

 

[Dougal]

I'm curious, how do you compare the two densities accurately? A formula? Is there perhaps a chart somewhere?

About half of a thermodynamics book. It's adiabatic compression modified for the efficiency of the compressor and then cooled by whatever effectiveness of the intercooler.

I've got spreadsheets setup to do all this.

 

[gerg]

Dougal is whom I go to for acurate answers, but the quick and dirty kind I get from intraweb sites!

http://www.stealth316.com/2-turbotemp.htm

Serously shove the widest and tallest thinest intercooler you can find onto your diesel. Who is measuring their quarter mile here to worry about the 2/10s more it takes to charge their cooler? magnus, yours looks really nice. You will get some very good numbers for effeciency. I would think in the order of high 70s%. Might not with the low boost as your not shedding that much heat overall. Intercoolers naturally become more effeceint with higher charge temps just like they do with lower ambiant air temps. The only improvement I would have done would be to offest the intake and outlet pipes to deminish the flow bias and even out the cooling across the core with internal baffels. For a stock ebay cooler it will still work well though.

 

[ForealBoreal]

Gerg,

I am looking at a treadstone performance intercooler (6x12x3.5) which has produced 90% efficiency at 24lbs of boost, coupled with their cool foiled end tanks. The core is rated to 750cfm which is good for 20lbs of boost on the 1hz at 8000ft. Why run a thinner core?

 

[gerg]

Now is that 6 inches wide as in the path the air takes across it, or does the air flow through the 12 inch section. Lots of intercoolers are designed for fit and not for effeciency. What I said is hard to describe, but is the intercooler long and narrow, or tall and skinny. Now that doesnt make and sence either, do you have a link?


So a 3.5 inch core is pretty thick for most normal fans to push air through. A front mount has an 8hp fan attached to it, so it can easily run air through. A top mount intercooler has a scoop to do it and and maybe an electric fan to help. I can tell you that I struggled to get any air at all through my 4 inch core with anything short of a 40 amp fan. I have a taurus fan I played with to test flow through the core. A normal cheapo 7 amp ebay fan couldnt drop my intake charge at idle 1 degree F in my driveway! Absolutely no air could be felt passing through the core at all. At highway speeds I was getting cooling, but effeciency was much lower (67%) than I thought the core could do. I think a good small spal fan would do the trick(40amps), but it doesnt get around the fact that the core is very very thick. Now stack a 3 inch fan on top of a 4 inch core and you get a serously tall set up for a top mount. A 3 inch would net greater passive effeceincy and would still have very little pressure drop at the cfms our engines put throught it and would fit much better.

The short of it is: if you want a more effecent intercooler, get one with lots of surface area that is shallow. Air flows through it easily with lots of internal volume for low pressure drop. Sadly, usually those kinds of intercoolers only like to fit in front of your radiator.