Intercooler theory and sizing debate

[Dougal]

Found this on the french forum.

But you will need to translate
Echappement Glaspack. - Page 2 - Forum 4x4

Same experiences as i had ....so

It doesn't translate well, but it can be read.
Translation result for http://www.forum4x4.com/forum/showthread.php?t=48471&highlight=glasspack&page=2

 

[rchalmers3]

Found this here: Peugeot 306 Dturbo - Turbo Diesel Information Mechanical & HDi

Performance Enhancing Exhaust Systems

"As with petrol cars changing the exhaust on a turbo-diesel 306 can increase the speed that the exhausts gases can leave the engine. The standard exhaust system on a 306 consists of exhaust boxes that contain baffles, which restrict the free flow of exhaust gases. Replacing these exhaust sections with free-flowing sections can dramatically reduce the restrictions in the exhaust system.


A typical turbo-diesel exhaust system has a bore of between 2 and 2.5 inches. It is not recommended to increase the bore diameter of your exhaust system as increasing the bore of the system will actually slow down the speed of the gasses flowing through it. This will require the engine to work harder to expel the waste exhaust gasses which will mean less power to push the car forward!"


I'm interpreting these 2 paragraphs as meaning the designers are removing restrictions AND keeping the pipe size small to maintain a gas exit flow speed.

What is not clear is the relationship of the exiting gas flow speed and the effect of placing a load on the engine.

Regardless, this statement does not indicate the exhaust gas exit speed is affecting the turbine speed or torque.


Rick

 

[Dougal]

Found this here: Peugeot 306 Dturbo - Turbo Diesel Information Mechanical & HDi

Performance Enhancing Exhaust Systems

"As with petrol cars changing the exhaust on a turbo-diesel 306 can increase the speed that the exhausts gases can leave the engine. The standard exhaust system on a 306 consists of exhaust boxes that contain baffles, which restrict the free flow of exhaust gases. Replacing these exhaust sections with free-flowing sections can dramatically reduce the restrictions in the exhaust system.


A typical turbo-diesel exhaust system has a bore of between 2 and 2.5 inches. It is not recommended to increase the bore diameter of your exhaust system as increasing the bore of the system will actually slow down the speed of the gasses flowing through it. This will require the engine to work harder to expel the waste exhaust gasses which will mean less power to push the car forward!"


I'm interpreting these 2 paragraphs as meaning the designers are removing restrictions AND keeping the pipe size small to maintain a gas exit flow speed.

What is not clear is the relationship of the exiting gas flow speed and the effect of placing a load on the engine.

Regardless, this statement does not indicate the exhaust gas exit speed is affecting the turbine speed or torque.


Rick

I'd question the understanding of the person who wrote that. Afterall is it easier to breathe through a smaller straw or a larger one?

If the gases are travelling at a higher velocity (as they do in a smaller pipe or straw) then it takes more power to give them that velocity. This power is called a pumping loss.
It's simple physics and like the HHO generation crowd there're an amazing amount of people with anecdotal evidence which is entirely bogus.

If an exhaust change gave me the wrong result, the first thing I'd be doing is hooking up gauges to find out what exactly was going on. Not swapping it for something else.

 

[syche]

Just one question....but..don't hit me

Why Mr toyota, Nissan Isuzu and all the other do not use so big exaust pipes if ti is the solution for power gain......And they are using huge amount of $ to set up their engines.
My father sell them tons of sensors for engine devlopment application.....

 

[Dougal]

Just one question....but..don't hit me

Why Mr toyota, Nissan Isuzu and all the other do not use so big exaust pipes if ti is the solution for power gain......And they are using huge amount of $ to set up their engines.
My father sell them tons of sensors for engine devlopment application.....

They all use bigger exhausts on more powerful engines. The reason they use silencers and smaller pipes on production vehicles are:
1. To meet noise regulations. Smaller pipes are quieter.
2. To save money. Bigger pipes cost more than smaller pipes.
3. To encourage the drivers to upshift rather than revving the snot out of the engines.

A great example is the recent Isuzu Trooper (bighorn). The engine power was increased several times through production and the exhaust pipe size grew with each revision.
From mechanical injection to electronic injection pump, then to unit injection.

Have you noticed that race engines (where performance matters) use big pipes with no silencers?

Most people confuse backpressure with scavenging. Scavenging is using the pulses in the exhaust to good effect and can make a big difference to many engines. Back pressure is always a bad thing, it costs both performance and fuel economy.

When industrial engines are rated, they usually include test information like exhaust backpressure or fittings in the performance charts. Like this one:
ISUZUerformance Curve


Do you run any extra instruments in your vehicle? I'd like to know how the boost and EGT's behaved with your exhaust swap. These two figures can tell us exactly what is going on.

 

[syche]

I don't have the car anymore...i have now an HDJ80 to upgrade. the boost was 950gr, almost 15 PSI and no IC.
on the french forum, one had 15PSI, PWR IC 4x6 water/air, and EGT bellow 500 as far as i remember, but without IC..it was about 600/650 full boost.

On race in US, maybe, but in europe, they all run small muffler and not huge piping.

I think the stainless made on my 80, made by Madac before i baught it (race exaust) is 2.5 or 2.75" and the rest is all factory.
Compare to my mate 100% factory, the turbo push in 200RPM higher..

I am in China, i just saw a patrol made for race like winch challange and other.. with...KZT engine and IC, it has a 40cm pipe after the turbo, look like a 2.5".
It make noise like hell, but i don't feel it pushing that much...

Why when me and my mate tryed the freeflow after reading post in US and Ausi forums we have so bad result.
No mater patrol, KZJ, HDJ, or HJ61....
that i don't get it.
But mount a complete ligne techinox or one of this small glasspack, you can really feel a difference, Better turbo response a low rev+ better torque+ more middle and high power.

That, i don't get.

What exaust piping are you running on 3L TD? I think we have 2.25" or 2.5" max

 

[Christian]

I know this is a side-step from the current discussion on exhausts, but if we were to change the head I would like to know the differences between the years. I have seen some advertised a "late model" will they fit? What should I look for to be sure that it is the "stronger" model?

 

[Dougal]

I know this is a side-step from the current discussion on exhausts, but if we were to change the head I would like to know the differences between the years. I have seen some advertised a "late model" will they fit? What should I look for to be sure that it is the "stronger" model?

Don't know, the later model heads don't get taken off to see what's different, they just keep going.
I'd expect any head being sold now would be the later designs, I haven't heard of any incompatibility.

 

[Christian]

Thanks Dougal!

 

[syche]

You need to find a VN for a prado 120 north african version or also from some other countries. they use the latest version of the KZ TE engine with a top mount intercooler.

With this VN any toyota supplier can order you the right head.

We don't have it in france. i know guys were looking at that for it intercooler.

 

[crushers]

first, a larger exhaust DOES NOT increase power (horse power or torque) it allows the exhaust to move faster, it allows the EGTs to drop noticably. THAT is all it accomplishes (and maybe sounds cool to some)

if you take a stock truck and dyno it, then run the larger exhaust on the same truck WITH NO OTHER MODS and your results will still be the same.

what this does allow is an increase in fuel settings which in turn will increase the power.

 

[syche]

Ok Cruchers, Lower EGT with bigger exaust, maybe due to more room for the gaz to expand.

But how can we explain this missing power when replacement of the factory exaust with a straight through tube?

And nothing else was touch when replacing exausts.

 

[lshobie]

Hi Christian, I have never owned or even driven a vehicle with that engine, but from what you are applying that engine to I can say that it is a bad idea. That truck of yours has the aerodynamics of a brick, has 6 large wheels to turn and is very heavy. I know that a skidder uses a 64 hp engine and because of its gearing has no problems, but your truck has to climb long hills, tackle headwinds and travel long distances. With that engine and its known problems you are asking for problems with your application.

I know that you have convinced yourself that this is the engine you are going to use and I am capable of convincing myself of things as well - but usually my bad ideas cost me money.

Please send video of your truck going from 0-100kms/hr, climbing a long hill at highway speeds and the EGT and water temp gauges. If you ask for opinions and ideas on here you will get them here wether you like them or not.

Good luck with your project I hope you prove me wrong.


Louis

 

[syche]

Guys this truck if from an other world.

The gearing will not permit such high speed, but will give any engine a pulling capacity that we do not know on our toyota stock.

Remember, the axle ratio...7:1, even with big tires it will still be a short gearing compare to the final 4.1/4.3 and 4.56 used on KZJ 9 and 7 series.

 

[crushers]

well,
Peter Straub installed unimog axles into his BJ60 with the idea of a off-road / DD and ended up as a off road only rig. (of course the 53" tires did little for his DD idea).
so yes, with the right gearing a KZ will move a vehicle down the road... of course then reliability, the depth of your wallet will be the next factors to consider.

i run a max of 3" (usually only 2.5") exhaust on any of my vehicles. i have very little experience with the straight pipe but i know a few guys that have with no ill side effects. in your case i have to lean towards something other than the exhaust that came into play. i was not there, i can not see there from here so sorry, no further advice i can give.

and the free flowing exhaust allows the exhaust gasses to move quicker away from the turbo reducing the temps.

 

[lshobie]

I have a 3 inch mandrel bent system on my truck with an aeroturbine exhaust - I love this system. At idle and moderate throttle it is quiet but when I put the throttle down it really barks and sounds great. I will probably put a 4 inch downpipe on it this summer if I can fit it in - as well as an external waste to keep the dirt and salt out of the mechanical workings of the internal.

Add all the gearing you want - your truck will work that engine. This is going to be a long haul vehicle as I understand it so it will be interesting to see how it fares out.

Louis

 

[Christian]

Hey Louis, i hope so too!

From this side of the pond it doesn't look that bad. I referred earlier on the trucks we get here. But it seems that there is a big cultural difference in how we view what output is needed. We are aiming at a top speed of 110 km/h. That is the legal limit most places here. if we have gear down and take it a bit slower, that's what we will do.
And as I've also said before, no one has done this before, so I am not 100% sure of success, but if no one tries, well we'd still be eating cold food right?

Just to give you an example, a Toyota Coaster bus like this:

It is 6.99 x 2.02 x 2.58 meters and wheighs 3390kgs and on top of that seats 29!

Has a 1HZ non-turbo engine!

Here's a comparison with the 1KZ:

1HZ: hp:135@4000rpm torque:187@2200rpm
1KZ: hp:125@3600rpm torque: 218@2000rpm

The fact is that I will go through with the swap. Don't get me wrong, I truly appriciate all your input, but I have driven this truck at more than 100km/h with the original 1975 de-tuned Volvo B30 with double Stromberg carbs, and I know the 1KZ is considerably more powerful!

A very popular conversion is putting a Mercedes OM603 engine in it, it has just about the same power as the original Volvo engine. You can buy a kit for it.

Another issue is reliability. I do not want to stress the rest of the driveline by going for much greater power than the original truck has.

And if you read on other forums, like expeditionportal, one of the things people like more about the volvo than the pinz or Unimog is the on-road speed.

The purpose of this thread was to get some pointers on intercooler size, preferably some sort af calculation tool saying: "if you have x amount of volume at @ rpm at z turbopressure your intercooler should be of y volume"... So others could use it too.

 

[crushers]

and as with most of the threads, tangents occure.

best of luck with the build.

 

[Christian]

and as with most of the threads, tangents occure.

best of luck with the build.

yup! -And thanks!

Btw, I have looked at the whole exhaust thing, and there's posts on UK forums with the same experience as Syche's. So I looked around some more, and the reasonable expelanation must be that you can go too big on exhausts.
The theory is that too big an exhaust actually slows the gasses down and in doing so creates more back-pressure. I found evidence of this on Ford Powerstroke forums as well. The sentiment seems to be that the pipe diameter should be more or less like the axhaust port on the turbo.

I cannot say that the above is correct, but it is a possible explanation that correlates with the feeling that the engine looses power in the top end.

Actually i do not think we can get closer to an explanation without doing some real-time measurements on back-pressure, Hp etc.

 

[crushers]

those engines rev to 4700... who would want to rev thae engine that high?
you should be driving around 1800-2500 on the highway so your top end should not be part of this equation..
i have taken a HZTI for a boot with NO exhaust and the thing pulled like a bugger... something just isn't jiving here.