D21 - Water/Air Intercooler

[The Stranger]

Well I started modding my TD27T by doing all the "usual" stuff. 2 and a half inch exhaust, remove all smog gear, clean out the manifold, fit a K&N filter, tweak the boost a tad (up to 12 psi) then fitted and EGT gauge and whoa! I got more power ok, but I couldn't use it. It was way too easy to spike to 800c in an instant.

I frequently found I had more power available but couldn't use it for fear of roasting the motor (I set a limit of 700c)

I figured cooler air in should hopefully = cooler air out so an intercooler was in order.
Decisions (well my thoughts anyway)
Top mount - Low lag, but figure not so great lugging at low speed and have to hack bonnet.
Front Mount - Simpler (in general) but more lag and tricky pipe runs.
Water/Air - Low lag, Simpler fit and can handle lugging at low speeds (for towing). On the down side I could find few good reviews and managed to find a few negative ones.

So naturally I chose W/A.

In short, the water/air rig is freaking awesome (so far). Fairly easy to fit and it's made a heck of a difference. No detectable lag, I've kicked boost up to 14psi and increased fuel 1/4 turn and the thing is a rocket (well figuratively) and so far the heat max out momentarily at 680c. So not only has it more power but I can use the power it already had.

And that's without the water system hooked up yet. I have a scuby pump and radiator now installed for the water cooling, just need to hook up the header tank (hopefully tomorrow) and wire in the pump.

[rob-mu]

I'm surprised you got such a big gain without the water system hooked up!

[The Stranger]

I'm surprised you got such a big gain without the water system hooked up!

Same here, but there is a heap of ali in that unit and it is in a natural cold air path - having cut the grille and removed the rubber over the head lamp.

I'm sure that under load (towing the boat) heat will not be disipated quick enough without the water system. But for anything that I can throw at it around town or hiway it is fine at this stage.

I hope to have the water system hooked up by weeks end and see what difference that makes.

[kbjj]

Nice, I'm watching with interest. What size intercooler did you use? (so I can order same\simalar size)

[The Stranger]

Nice, I'm watching with interest. What size intercooler did you use? (so I can order same\simalar size)

Here is the one that I used.

And due to a slight change of plan it may take a little longer to complete.
I have a Subaru water pump and radiator mounted now (not in photo), but I'm not 100% happy with the radiator as it will stuff up my trans cooler. So I'm going to have a radiator and header tank made - now completion will depend on the shop.

[passengerpete]

i finished mine in weekend... well mostly. its a subaru rs one too just moved around a bit to suit the td27 will add pic if want

[The Stranger]

i finished mine in weekend... well mostly. its a subaru rs one too just moved around a bit to suit the td27 will add pic if want

What's with the suspense?
Yes please photos and a review would be awesome.

[slide]

i finished mine in weekend... well mostly. its a subaru rs one too just moved around a bit to suit the td27 will add pic if want

Yea, I'd be keen to see picture. And where are you mounting the intercoolers radiator? Pics of that would be good to.

Great for the inspiration

[passengerpete]

[passengerpete]

have made brackets to mount inter-cooler, just need to to make a spacer of 25mm between the plenum and the 90 intake bit. i have not driven it far as the auto shat it self when testing a mock set up.

[The Stranger]

Snip Images

A few questions if I may.
1) That looks about the same as the way I mounted the Subaru radiator, I note the hoses off to the left (RHS of the vehicle) do you have a trans cooler behind the IC radiator?

2) The subaru IC looks the same as the unit that I had - but mine had the inlet and outlet on the same side. Do you have a photo please of the underside of the IC? Because if that one is different that would be way easier (and cheaper for sure) than the way I have done mine.

[passengerpete]

yes trans cooler fits between the heat exchanger and radiator

all i did was cut and rotate

[The Stranger]

Nice, I'm watching with interest. What size intercooler did you use? (so I can order same\simalar size)

I now have the radiator and a remote header tank hooked up. The pump is mounted, but not electrically connected yet.

As I suspected, simply filling the system with water has produced an improvement.
I am now running 15psi boost and I haven't managed to get the EGT over 630c so albeit on a very unscientific comparrison it would appear that I have dropped another 50c. General driving appears to confirm this almost across the board i.e. in all conditions not just when loaded.
Another thing that I have noticed is that it seems to reach max boost quicker.

The Terrano was bought specifically for towing and beach launching the boat. My goal was to achieve 15psi boost and not exceed 700c EGT when under load of towing up long hills. I'm very confident of achieving this especially with the water pump connected. I may yet even be able to tip in more fuel and keep within those parameters.

[The Stranger]

Water pump is now hooked up.

Not what I expected. Previously I had been using EGT as a metric. When I installed the W/A intercooler EGT dropped, when I filled it with water EGT dropped. Now with the pump connected EGT has gone up.

Air temp after the intercooler has gone down by about 30-40 degrees (though I could bring the pump in sooner if I want to) and for the first time I note a significant difference between the temp of the inlet and outlet air plenums on the IC. So I know the pump is working and the IC is doing it's job.

So why has the EGT gone up again?
Ok it's still lower than it was when I started this exercise - by quite a lot.

The other things I note are.
1) Around town the EGT is certain lower.
2) Hits full boost (15psi) even sooner.
3) On a standard hill test starting at usual speed and holding 15psi boost I glanced at teh speedo and was doing an additional 15kph at the top of the hill, so maybe the additional EGT is as a result of additional power?

[tomsoffroad]

My understanding is (fabricator, not mechanic ) that the colder the air the denser (fabricator not spelling bee champ ) it is. Therefore more "air" jambed into the combustion chamber. More "air" jambed in = bigger bang = higher combustion temps.
Maybe you need to add more fuel to the equasion?

Awesome looking set up you've got there and it sounds like it has heaps of potential.

[crazyclark31]

My understanding is (fabricator, not mechanic ) that the colder the air the denser (fabricator not spelling bee champ ) it is. Therefore more "air" jambed into the combustion chamber. More "air" jambed in = bigger bang = higher combustion temps.
Maybe you need to add more fuel to the equasion?

Awesome looking set up you've got there and it sounds like it has heaps of potential.

Your partly right there tom. the bigger bang is but if your concerend about egts i wouldn't go putting any more fuel in. In saying that if they are only round the 450 mark at the top of your test hill then you've still got a bit of room to move

[u13turbo]

Would it be safe to run 16PSI with everything else standard? just the water/air intercooler?

[The Stranger]

Your partly right there tom. the bigger bang is but if your concerend about egts i would go putting ant more fuel in. In saying that if they are only round the 450 mark at the top of your test hill then you've still got a bit of room to move

Without and IC at all it would hit 800c in a flash if one weren't careful on test hill with 12psi boost max. I have no idea if it would have gone higher, I wasn't keen to try.

With the IC installed, but Without the pump running 630c at the top of the hill - holding steady 15psi boost and very noticable increase in power.

With the pump running 700c at the top of the hill again holding a steady 15psi boost. But this time I notice that I have a higher velocity at the top.

It has to be a pretty inaccurate test, but it's one of the few that I have without a dyno etc and I'm happy that the EGT gauge is good and I have decent measuring equipment for the air temp going into the inlet manifold and as noted that is down about 40 degrees from peak - though it varies depending on load etc.

[crazyclark31]

were is you probe fitted? 700 is getting up there even a bit on the high side. Any smoke when boosting?. there are a few options to fix the temps

[darinz]

700*c is absolute max for a TD (27 or 42) due to the pre-combustion chamber design. The temp coming out of the pre-comp is high at 700*c egt. Any higher and you're close to burning a hole in the piston. So yes other motors may run much higher egt without problems but you need to understand what is inside your motor so as to inderstand when damage is happening.

The I/C has done 2 things. Decreased air temps and increased air density (and so oxygen). The decreased airtemp with directly relate to lower egt's (eg 50* lower will mean 50* less egt) and the denser air will mean more fuel burnt. The cause of high egt's in a TD (27 or 42) is unburnt fuel. The denser air means more complete combustion and so lower egt and more power.
Now here is another problem. When you increase the boost with the factory turbo you start to put the turbo outside it's effecient range. This means it is spinning too fast and so creating alots of heat. So the I/C cools the air down but it is still not as dense as at 12psi (assuming you have gone to 14psi) and you have increased the fuel. The increase in boost has a direct co-relation to the amount of torque so the truck goes better. But the egt's go up as you now have more unburnt fuel. So turn the fuel back a bit and you'll keep the torque (and so performance) but will decrease the egt's.

[The Stranger]

were is you probe fitted? 700 is getting up there even a bit on the high side. Any smoke when boosting?. there are a few options to fix the temps

The probe is fitted in the manifold just before the turbo.
Pretty much no smoke at all. I say pretty much as there is a tiny puff on start up sometimes, but there is none at all when it is running - it has a Rage big bore exhaust on it and the tail pipe is clearly visable from in the LSH wing mirror.

[The Stranger]

The I/C has done 2 things. Decreased air temps and increased air density (and so oxygen).

Ok, I admit it, this one has me confused.
Are you saying that the IC somehow increases the amount of oxy?
I would have thought that after the air had entered the intake tract that's pretty much it. I mean if air loses oxy when it gets heated by the turbo where does it lose it to? I been losing oxy to somewhere for the last 10 years (before I had an IC), I wouldn't mind knowing where it is now as I could make a pretty mean acetylene bomb.
If it gains oxy at the IC where does it gain it from?

Now prior to entering the intake track I can dig that cooler air is more dense and can contain relatively more oxy, but once it's in "the system" surely that's it isn't it?

[crazyclark31]

nope it packs it in so its denser. It doesn't lose or gain the oxy.The hot air is less dense so less air(oxy) per square cm of space. once air is cooled it becomes more dense so more air(oxy) per square cm of space. because the same volume of air now takes up less space you can fit more air(oxy)into the motor. this also causes a small pressure drop on the intake side of i/c.But don't be tempted to wind up the boost as it will put the turbo further outside its efficent range therefore making the air hotter.

Do have to agree with darinz. Try turning fuel down just a little and see what happens.

[The Stranger]

700*c is absolute max for a TD (27 or 42) due to the pre-combustion chamber design. The temp coming out of the pre-comp is high at 700*c egt.
...
So turn the fuel back a bit and you'll keep the torque (and so performance) but will decrease the egt's.

Do have to agree with darinz. Try turning fuel down just a little and see what happens.

So ok, I have backed the fuel off quarter turn and it has lost a lot temp (EGT) but also lost a lot of power and "drivability".
So, my question is, what is a safe EGT? - measured just prior to the turbo.

[kbushnz]

1/4 turn might be too much...
Half it and turn it up again 1/8 and check again...
Small adjustments can have big effects...

[sibainmud]

I'm on my second tweak up of a TD27. The first one was still running the non-turbo fuel pump so had a tendency to over-fuel before the turbo spooled up but i learned to drive it using my foot as the governor.
The next one (T2), i used the same method to turn up the fuel. When it was standard, I turned the fuel up while it was running until it was idling at 1100rpm and then adjusted the idle stop so it was idling at 750rpm. I had to slacken off the throttle cables (hand and foot) to allow the extra travel to achieve this. With a half blocked air filter and under full load in 5th going north up the Bombay Hill, it maxes out at 550-600deg C with 18psi boost. It has heaps of power and runs sweet.
1/4 & 1/2 turns mean jack when it comes to tweaking fuel.
It is a fine balance of fuel and air that gets the best "bang" without it burning half the fuel in the exhaust causing high EGT's.
When the balance is right the thermal expansion spools the turbo up fairly quick and the power gains become exponential.
I hope this helps.
Cheers,

[wax]

If the egt,s are to high then just turn the boost up higher

[The Stranger]

I'm on my second tweak up of a TD27. The first one was still running the non-turbo fuel pump so had a tendency to over-fuel before the turbo spooled up but i learned to drive it using my foot as the governor.
The next one (T2), i used the same method to turn up the fuel. When it was standard, I turned the fuel up while it was running until it was idling at 1100rpm and then adjusted the idle stop so it was idling at 750rpm. I had to slacken off the throttle cables (hand and foot) to allow the extra travel to achieve this. With a half blocked air filter and under full load in 5th going north up the Bombay Hill, it maxes out at 550-600deg C with 18psi boost. It has heaps of power and runs sweet.
1/4 & 1/2 turns mean jack when it comes to tweaking fuel.
It is a fine balance of fuel and air that gets the best "bang" without it burning half the fuel in the exhaust causing high EGT's.
When the balance is right the thermal expansion spools the turbo up fairly quick and the power gains become exponential.
I hope this helps.
Cheers,

If the egt,s are to high then just turn the boost up higher

Yes it does help thank you guys.

Increased fuel over where I had it and increased boost and voila - it springs into life with the best power and lowest EGTs yet.