Quick intercooler question....

[neal1980]

Ive had my large front mount intercooler chopped up and had it re-welded to make it smaller so I have more air going to the rad. This has made my water temperatures much more stable and the turbo air temp has not suffered at all really its 1-2 degree higher.

I seem to have gone from 9psi down to 5psi now and nothing else has been changed. How can this be?? I have taken the intercooler back off and pressurised and its holding pressure so cant be a leak / bad weld.

I thought you would only see pressure drop if going the other way i.e small intercooler to large intercooler.

[anonymous-user]

er, smaller is like to mean "more restiction"........


Depending on where you take your boost control signal from (most likely the compressor exit scroll) you plenum boost pressure will be your compressor exit pressure minus your intake system pressure loss. By reducing the size of your IC you seem to now be loosing 4psi across the cooler!.

Either A) move your boost control pressure feed to the your plenum (which will restore full boost to the plenum (at the expense of more turbo "work" and higher compressor outlet temps) or B)fit a better IC unit

[anonymous-user]

I should also add that most "aftermarket" intercoolers are not designed well. People just do the old "bigger must be better" thing and make massive but terrible flowing intercoolers, with hideous changes in area, subcritical bend radii, and poor air distribution between the laminar cooling section and the expander / contractor end caps etc)

[neal1980]

Max_Torque said:

er, smaller is like to mean "more restiction"........


Depending on where you take your boost control signal from (most likely the compressor exit scroll) you plenum boost pressure will be your compressor exit pressure minus your intake system pressure loss. By reducing the size of your IC you seem to now be loosing 4psi across the cooler!.

Either A) move your boost control pressure feed to the your plenum (which will restore full boost to the plenum (at the expense of more turbo "work" and higher compressor outlet temps) or B)fit a better IC unit

Boost pressure feed is off the plenum already. Just put it back together so about to try again, so worst case I can up the boost again to get back my 9psi pressure making the turbos work a bit harder??

Next winter I plan a new intercooler / rad setup this is just to get me my last few months on the road now I have paid for tax / insurance.

• *Update***

Just tried again what a pile of wk, making 3 psi not spinning up till really late in the rev range I dont understand how this can be possible. Ive halved the intercooler from 26 row to 13 but its still a fair size. It was an ebay rs500 job. Would a bad flowing intercooler really do this?? Ive pressure checked it and its fine not leaking at all, most of the pipe work is alloy and no leaks there.

Edited by neal1980 on Friday 15th July 15:15

[chuntington101]

Max_Torque said:

I should also add that most "aftermarket" intercoolers are not designed well. People just do the old "bigger must be better" thing and make massive but terrible flowing intercoolers, with hideous changes in area, subcritical bend radii, and poor air distribution between the laminar cooling section and the expander / contractor end caps etc)

Max, can you point us in the direction of some intercoolers that are designed properly? It would be intresting to see / understand more about intercooler, inperticular end tank design and how to get good airflow across the whole core.

[stevieturbo]

Depends entirely how you cut it.

Try a little test. Take a straw and breathe through it. Will be difficult for sure

Now take two straws. Which would you prefer ?

And yes the straws are small, but you dont consume anywhere near the volume of air that an engine does. But you have just halved what it has to breathe through.

Although dropping from 9psi, to 6psi, and then 3psi would suggest a problem perhaps elsewhere.

[anonymous-user]

Are you measuring boost pressure in the plenum?

Where is your wastegate pressure tapping taken from?

Does your system have a "boost control valve" or is it just running a fixed pneumatic actuator?

The issue may not be entirely in the cooler, if you have also changed the pipe work and entry conditions you may also have issues there

Are you sure your turbo is producing the correct boost pressure at the compressor outlet?

[stevieturbo]

Or maybe he's using one of those dodgy compression testers knocking about ? lol

[eliot]

neal1980 said:

Ive halved the intercooler from 26 row to 13 but its still a fair size. It was an ebay rs500 job.

If you would of shortened the length of the rows, then i would expect to see less cooling and perhaps a little more flow.
But by removing rows, you have effectively reduced the diameter which now seems to be causing a restriction.

[neal1980]

I have shortened the intercooler height wise see the pic below. Everything is exactly the same all the pipe work etc. Most of the pipe work is alloy apart from a few stubby silicone bits and these are all fine and very secure.

My take off for the boost gauge is the plenum and the take off for the actuators is from the turbo housing, I plan now to tee it to this and get a reading before the intercooler.

On the dyno I had the power taping off really quickly and maybe my intercooler has something to do with this. Nothing else has changed at all just removing approx 13 rows. Its still a fair size intercooler even now.

I def now get approx 3-4 psi and when in 5th it goes to 5-5.5 psi and used to be 9 through the gears.

If my intercooler is really this wk I will be taking an axe to it lol

Pic of original is from ebay so might not be exactly the same but you get the idea.

[stevieturbo]

You really have reduced the flow ability by a massive amount there.

Do you have room to use the old section to create a much thicker core ? Yes it is far from ideal, but it will improve airflow through the core, albeit cooling efficiency will decrease ( for given core size, but in general it would be better than what you have now )

And when space really is an issue. Core design really does become more important.
Cheap egay cores work well because in most instances they are just far bigger than people need.

But when the core is too small, it's critical you get a good one.

[neal1980]

Thanks for help so far guys.

I have just plumbed my boost gauge in before the intercooler on the actuator wastegate port and I get roughly the same boost 5psi. So I am getting 1-2 psi drop across cooler after all.

But where is my missing 4 psi gone I dont understand now. My intercooler was holding pressure when I checked it, would a tiny hole maybe hold pressure but lose 4psi??

Shall I wind the boost out more, make the turbo work harder to get my 9psi back or check something else??

Thanks

[eliot]

neal1980 said:

would a tiny hole maybe hold pressure but lose 4psi??

I left the air sensor out of my plenum (1/2" hole) and i still made reasonable boost - so I wouldn't of thought so (unless my turbo's are capable of loads more than i'm asking of them)

[stevieturbo]

neal1980 said:

Thanks for help so far guys.

I have just plumbed my boost gauge in before the intercooler on the actuator wastegate port and I get roughly the same boost 5psi. So I am getting 1-2 psi drop across cooler after all.

But where is my missing 4 psi gone I dont understand now. My intercooler was holding pressure when I checked it, would a tiny hole maybe hold pressure but lose 4psi??

Shall I wind the boost out more, make the turbo work harder to get my 9psi back or check something else??

Thanks

You sure nothing else was touched or changed during the work ?

Are you getting wastegate pressure only, or are you bleeding off ?

[neal1980]

stevieturbo said:

You sure nothing else was touched or changed during the work ?

Are you getting wastegate pressure only, or are you bleeding off ?

No nothing at all just intercooler off and back on, I am bleeding off as well.

Makes no sense to me should I just bleed more and see what happens I dont know what else to do now.

[Steve_D]

neal1980 said:

Thanks for help so far guys.

I have just plumbed my boost gauge in before the intercooler on the actuator wastegate port and I get roughly the same boost 5psi. So I am getting 1-2 psi drop across cooler after all.

But where is my missing 4 psi gone I dont understand now. My intercooler was holding pressure when I checked it, would a tiny hole maybe hold pressure but lose 4psi??

Shall I wind the boost out more, make the turbo work harder to get my 9psi back or check something else??

Thanks

It's nothing to do with leaks.
The turbo is simply trying to suck air through a hole half the size it was before so not suprising it is not having too much success.

Steve

[freecar]

I don't think you understand how an intercooler works.

The pipes coming in are essentially flattened out to create a much larger surface area so the airflow can cool it. This is spread out over a bunch of little pipes, you have removed a bunch of these and are expecting air to flow through it the same.

As a previous poster mentioned, shortening the height will impede the flow, shortening the length will not.

I'm afraid I have no solution for you though, just an explanation of what has happened, I wouldn't expect you to get your original boost pressure back with that intercooler easily.

[eliot]

Steve_D said:

The turbo is simply trying to suck air through a hole half the size it was before

Blowing more like.

[Steve_D]

eliot said:

Steve_D said:

The turbo is simply trying to suck air through a hole half the size it was before

Blowing more like.

I knew a young lady who also got that the wrong way round.

Steve

[slideways]

neal1980 said:

I have shortened the intercooler height wise see the pic below. Everything is exactly the same all the pipe work etc. Most of the pipe work is alloy apart from a few stubby silicone bits and these are all fine and very secure.

My take off for the boost gauge is the plenum and the take off for the actuators is from the turbo housing, I plan now to tee it to this and get a reading before the intercooler.

On the dyno I had the power taping off really quickly and maybe my intercooler has something to do with this. Nothing else has changed at all just removing approx 13 rows. Its still a fair size intercooler even now.

I def now get approx 3-4 psi and when in 5th it goes to 5-5.5 psi and used to be 9 through the gears.

If my intercooler is really this wk I will be taking an axe to it lol

Pic of original is from ebay so might not be exactly the same but you get the idea.

HI Neal
Have a look how mines been made don't know how it will perform but it has 3 passes which double in size on the first pass to allow for the second turbo



will have more photos when the outlet is welded on!