Effect of intercooler pressure drop on turbo (1 Viewer)

[David60series]

Hypothetically, if I was running a stock CT26 turbo at 11psi measured at the manifold and fitted an intercooler I would likely see a pressure drop if u measured boost at the same point.

Let's say this drop is 3psi. My boost is now 8psi. If I use a boost controller to increase this back to my humble starting point if 11psi, am I now really spinning the CT26 to 14psi?

As such, how important is it to compensate for the lost boost or is 8psi cooled to ambient temp better than 11psi at compressed temperatures?

I ask this as, hypothetically, it would be easy to run outside the speed parameters of an old CT26 if you were chasing boost drop.

 

[Lumpskie]

I don't know any actual numbers for intercooler pressure drop but I wouldn't worry about it. Let's say that your 3psi example is correct. In that case, adding an intercooler would effectively do the same thing as driving your rig from sea level to 6000 ft. (since air gets thinner as you climb higher) So, the turbo would have to spin faster to maintain your current boost settings.

But the real key with the intercooler is that, at the reduced pressure, your mass flow will be the same. So, for your example, you'll loose 3psi with the addition of the intercooler but you'll be moving the same amount for air through... it will just be denser!

 

[mudgudgeon]

I agree with above.
If your waste gate signal line is at the turbo, pre-intercooler, before any pressure drop is experienced, it's a moot point as the waste gate still gets the same signal

 

[Sarmajor]

If you install a boost controller it should be connected in circuit between the turbine and the waste gate. The pressure should be measured at one of the ports on the crossover pipe from the turbo to the inlet manifold.
You can adjust the pressure in the manifold to suit.
I adjusted mine so that it almost trips the over boost pressure switch. (about 14.5psi)
This gets me back to stock boost (or at least max allowed) measured after the Intercooler.

The Gturbo guy has posted a couple of images to illustrate the piping that I have used.

 

[David60series]

Thanks. That's good. So the learning is that I would not need to chase the pressure drop necessarily to get back to parity in performance.

I could strap on an intercooler to an old CT26 and see benefits through tuning without worrying about boost?

 

[David60series]

If you install a boost controller it should be connected in circuit between the turbine and the waste gate. The pressure should be measured at one of the ports on the crossover pipe from the turbo to the inlet manifold.
You can adjust the pressure in the manifold to suit.
I adjusted mine so that it almost trips the over boost pressure switch. (about 14.5psi)
This gets me back to stock boost (or at least max allowed) measured after the Intercooler.

The Gturbo guy has posted a couple of images to illustrate the piping that I have used.

This is the scenario I'd like to avoid...

This process would then see the turbo spinning at your 14.5 plus whatever the drop was, so 16 upwards?

 

[Tapage]

This is the scenario I'd like to avoid...

This process would then see the turbo spinning at your 14.5 plus whatever the drop was, so 16 upwards?

you can measure before and after IC.. but the real benefit should be on EGT's therefore on fueling therefore on engine effort to keep speed that develop more temps prior to IC ..

 

[Jentuh]

Why not connecting the wastegate pilot signal to the intake manifold? that way the wastegate will regulate the Boost pressure (at intake manifold) to the value set on the wastegate, no matter what pressure drop there is in between turbo and intake.. Or is this too slow in reaction?

 

[IanB]

Why not connecting the wastegate pilot signal to the intake manifold? that way the wastegate will regulate the Boost pressure (at intake manifold) to the value set on the wastegate, no matter what pressure drop there is in between turbo and intake.. Or is this too slow in reaction?

I think it would be slower to react, you want to keep the wastegate reference line as short as possible for this reason.

 

[mudgudgeon]

Why not connecting the wastegate pilot signal to the intake manifold? that way the wastegate will regulate the Boost pressure (at intake manifold) to the value set on the wastegate, no matter what pressure drop there is in between turbo and intake.. Or is this too slow in reaction?

Here's my understanding, not sure that I'm correct though.

If the turbo is waste gated to 15psi, and you are taking waste gate signal at the manifold, but have a pressure drop of 2psi after the intercooler, the turbo will be potentially pumping 17 psi.

This could be putting a turbo beyond its limits in durability and efficiency.

15psi at the turbo vs 13 psi at manifold after intercooling is still the same volume (or mass?) of air, but as is condensed you can potentially stuff more air in

 

[Jentuh]

Here's my understanding, not sure that I'm correct though.

If the turbo is waste gated to 15psi, and you are taking waste gate signal at the manifold, but have a pressure drop of 2psi after the intercooler, the turbo will be potentially pumping 17 psi.

This could be putting a turbo beyond its limits in durability and efficiency.

15psi at the turbo vs 13 psi at manifold after intercooling is still the same volume (or mass?) of air, but as is condensed you can potentially stuff more air in

I see what you mean, you can indeed push the turbo above it's limits.
The amount of air could be the same, as both pressure and temperature drops. I don't think there's a 1:1 relation to that though....
But isn't the main purpose of the intercooler to get more mass in? or would the same amount of air at lower temps only bring down EGT, and is that the main purpose?

In the future I want to build an intercooler on my 12HT, just gathering knowledge here

 

[Mcreight911]

Unless it's a poor quality intercooler the pressure drop at 11psi would be more like 1-1.5. Even eBay specials are 3psi drop at 30psi. If your worried set your desired boost before u put the cooler on, measured at the manifold if that's where you currently measure it. Once the coolers on note the new/changes max boost. That will tell you the exact pressure drop. Don't put a bleed valve and a boost gauge in the same line, you'll get an incorrect reading.

 

[Sarmajor]

I just retread my previous post and realise it has some errors.
This is a link to the original information that I used to redo my pressure lines and fit the boost controller.

http://www.peoplehelp.com.au/landcruiser/images/Gturbo pressure lines.pdf

The line from the turbo to the aneroid gets the fuel going as soon as boost is being made and the lines from the manifold use post Intercooler pressure to operate the waste gate and feed the gauge.

The whole boost fuel EGT equation is complex and requires clear thought and small steps as you experiment with cause and effect.

More air lowers EGT. More fuel raises EGT. More fuel means more power but only if there is enough air to burn it efficiently.
With an EGT guage you can monitor the effects of your adjustments and not risk cooking your turbo and exhaust valves.

EGT should be pre turbo for best response and most accurate measurement.

I spent a few weekends experimenting until I got things where I like them. Under heavy throttle up long hills I can get EGT's past 600C pre turbo if I don't lift off a little bit. But it only takes a small reduction in throttle (fuel) to get the EGT's to fall dramatically. Most cruising is done with EGT's in the 350 - 400C range. My truck is running just on 14 psi according to the Redarc Boost / EGT gauge.

Hope this helps.

 

[phatman81]

I like the idea of pre / post intercooler pressures ..

 

[Dougal]

3psi pressure drop means you need a bigger intercooler. >1psi would be acceptable.

 

[phatman81]

I shared some emails with a popular W2A Intercooler maker .. They were "UNWILLING" to discuss water flow rates and water temperature charts vs air temp with me .. What I wanted to know was ambient air temp range with their radiator KIT .. As we all know its not just the radiator air flow, its water flow and ambient air temp ..

The reason for me asking those questions to the W2A manufacturer was that I wanted to know the maximum ambient air temp range .. If it can't withstand 115 F ambient air I would go even to 125 F just to ensure that we can survive death valley .. They refused to give any operational spec's ..

I don't know about you but any Manufacturer of W2A that doesn't give full spec's for their "Stand Alone Unit" that they sell on their website is criminal .. How is anyone supposed to use their W2A chiller without full disclosure of the Intercooler ? ..

I'm not going to go into more details regarding the lack of cooperation from this popular company and the fact that they make Intercoolers for both 1HD-T & -FT ..

Why did I want to know about the spec's of their Intercooler ? Fair question, yes .. Because I found a Freon to Water Chiller .. By integrating a F2W chiller we remove Ambient air temps the lack of rammed air .. Now the question becomes rates of flow for water into the intercooler .. I told the W2A Intercooler company that my plan was to purchase "FOR MY USE ONLY" their stand alone Intercooler and marry it to a F2W chiller .. They refused to speak to me about any spec's at all ..