Intercooler theory and sizing debate (1 Viewer)

[Christian]

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.

I won't! It was in relation to Syche's experience, not related directly to my project. About the jiving; True! I'm only offering a possible explanation I picked up elsewhere. Here's a link to one article: Exhaust Theory

And here's a quote from a Garrett engineer: "There's more to it, though-- if a larger bellmouth is excessively large right at the turbine discharge (a large step diameter increase), there will be an unrecoverable dump loss that will contribute to backpressure. This is why a gradual increase in diameter, like the conical diffuser mentioned earlier, is desirable at the turbine discharge."

So all in all, there's more to it than just slapping some stainless pipes on it!

 

[Dougal]

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.

I'm currently running a 2.25" exhaust on my 3.9L Isuzu with 20psi boost, there is a noticable and measurable increase in backpressure as the revs climb. But the main suspect here is the muffler which was not intended for this much power.
Running calcs on my intended future output (30psi boost, 700C EGT's) gives 3kw difference in exit loss alone between a 2.5 and 3" pipe.

I believe most of the people reporting power losses due to bigger pipes are causing other problems and wrongly attributing it to backpressure. Backpressure is always the enemy, less is always better.
Transitions as Christian has noted are a big one. The pipe size doesn't matter (the atmosphere at the end of your pipe is similar to a pipe of infinite diameter) but how it necks out to that does. But even the worst transition will only cost you a couple of kilowatts in extra back pressure.

Many of those powerstroke observations (I've found similar) are on electronically controlled engines with variable vane turbos. I suspect the sensors start reading outside the intended range and start pulling back fuel.
However, none of these people have taken any pressure or temp readings to confirm or deny.

Bottom line, it takes power to pump gas, that power is lost from crankshaft output and that power loss increases as backpressues increases.

 

[crushers]

once again i have to agree with Dougal, the larger diameter exhaust will not be the issue.

the powersmoke people also like to pretend that a 6" exhaust will increase your horsepower and torque over stock. this is false and if you dyno the kit before and after (with no other mods) nothing changes in HP and Torque readings.

common sense has to come into the equation, if a turbo's HDT is running 2.75" exhaust then why would a HZT need any larger? unless of course you are not increasing the fuel which increases the EGTs which can cause issues so larger is better in this case.

now, was the KZ in question an electronicly controlled unit? could the system be misreading the sensors as Dougal pointed out? when i ran 2.5" on my 2LTE i never noticed any change other than quicker response from the turbo and lower EGTs...

 

[Christian]

To Dougal: That is true. I have also found some who claim that poorly designed exhaust elbows might be an issue. The reason should be that the exhaust from the dump valve is causing interference and thereby back-pressure. All speculative without measurements of course.

Crusher, I agree. And overall there must be other factors at play.

On the intercooler subject, I have found a used PWR 4x10" barrel, like this:

But as long as this:

With waterpump, hoses, clamp and water-radiator for 366.98 USD.
Seems like a good deal, any objections?

 

[crushers]

where did you find this setup for that money?
Louis is planning on the same setup for his rig and if i can find a decent location i am thinking for the HZJ40 build.
website please.

if it works as it should i might be changed from air to air systems permenately...

 

[lshobie]

UMMM, 366??? do they have more? I just bought the barrel alone for 490USD, now I need the rest of the kit.

Do you have a link to that seller?

Thanks

Louis

 

[syche]

Same, WHERE DID YOU FIND IT at this price, i want one right now!!

For my KZ as i said it was a KZT but similar things happen with LJ 2.5 td, KZTE, and KDJ engines.

The 6 inline from HDT seems a little less sensitive, but the guys keep the factory first muffler behind the front right wheel...

A guy from the forum made test with measurment on his KZT witha 4x6, results were great, not sure the 4x10 is needed for the 3L. I will try to find the thread for you, you will have all explainations about it.

 

[R2HKS]

Good to see you changed your mind about water to air IC's. That PWR 4x10 will do the job just nicely for you.

Its a steal at that price for the full kit.

 

[syche]

Here it is PWR 4x8 on KZJ73, ..in france sorry you will have to use google tranlator.

Monitorer l'admission (intercooler sur KZJ 73) - Forum 4x4

Regards to all

 

[Christian]

Thanks guys!

I have called him, and it isn't sold yet, but he would call me back later because he was working.

It is some coincidence though, it is the only water-to-air for sale here!

He used it on a Peugeot 205...

 

[Dougal]

To Dougal: That is true. I have also found some who claim that poorly designed exhaust elbows might be an issue. The reason should be that the exhaust from the dump valve is causing interference and thereby back-pressure. All speculative without measurements of course.

Turbulent gas flow is pretty well understood, there are tables which list K factors for different size and shape pipe fittings. These relate pressure drop across each fitting to the exit loss you get at the end.

Here's one of those tables, take a look through and you'll see smooth bends are quite low (K ~0.3), only getting up around K=1 for long bends where the length of pipe becomes a big factor.
http://www.uofaweb.ualberta.ca/mece/pdfs/MEC E 330 - Supplemental Package 11b.pdf

It's gotta be a very ugly bend to have a big impact on backpressure. Even a 90 degree mitre bend has a K value of only 1.6.

 

[crushers]

oh, a used system... okay. hope you snag it then.
i was hoping for new for that price and i am sure there are a few of us after them.

 

[Christian]

Turbulent gas flow is pretty well understood, there are tables which list K factors for different size and shape pipe fittings. These relate pressure drop across each fitting to the exit loss you get at the end.

Here's one of those tables, take a look through and you'll see smooth bends are quite low (K ~0.3), only getting up around K=1 for long bends where the length of pipe becomes a big factor.
http://www.uofaweb.ualberta.ca/mece/pdfs/MEC E 330 - Supplemental Package 11b.pdf

It's gotta be a very ugly bend to have a big impact on backpressure. Even a 90 degree mitre bend has a K value of only 1.6.

Damn, that chart is thorrough! But, again this is rather speculative, the idea as I understood it was that the pulse-effect, like that in a n/a engine, coming from the dump valve caused the issues, not the elbow or bend itself. The recommendation was that the dump valve was routed 12-18" down the exhaust by itself, before it joined the rest. Preferably not joining at all.

 

[Keros]

Damn, that chart is thorrough! But, again this is rather speculative, the idea as I understood it was that the pulse-effect, like that in a n/a engine, coming from the dump valve caused the issues, not the elbow or bend itself. The recommendation was that the dump valve was routed 12-18" down the exhaust by itself, before it joined the rest. Preferably not joining at all.

If I follow this correctly, as that I read page 1 then skipped to page 4... I don't have too much time, you're referring to the wastegate (aka Dumpvalve, apparently)... and having it's exhaust exit recirculate into the main system later down the downpipe. This is what's known as a Divorced Down Pipe and is extremely effective at keeping exhaust moving down the system by reducing turbulence. A popular thing to do is to give the wastegate's outlet it's own muffler and not bother recirculating it... motor cycle mufflers work well, apparently. Keep in mind that an open wastegate to atmosphere is essentially no exhaust system at all... so when that sucker cracks open, it's gonna be LOOUUUDDDDD!

As for the intercooler itself, and I don't know if it was covered in the 3 pages I skipped (if it was please forgive me ), you want the smallest intercooler that will meet your requirements, then add a few percent to that size. If it were me, I'd be calling up a nationally reputable tuning shop and explaining what you have and what you need. I've heard good things about Extreme Turbo Systems, Titan Motorsports, and Wide Open Throttle Motorsports in the states, but RCTS is who I would phone, being as that I'm in Canada.

As for the side/side or same side intercooler, that depends on how your intake is positioned relative to your turbo's compressor outlet. Use the intercooler that produces the least amount of pipe routing because each bend will cut engine response and increase heat soak from engine tempratures.

Ceramic coat the hell out of everything that gets heated. Especially the turbine section of the turbo... it gets smokin' hot. You want the heat to go down the exhaust pipe not into the engine bay. It's not uncommon for a turbine to glow red after some hard driving; ceramic coating, a turbo blanket and exhaust wrap on the exhaust manifold (and ceramic coating) will decrease engine bay temperatures substantially by keeping hot metal and air seperate. If you have the engine apart, do not ceramic coat the combustion chamber without doing the piston, or vice versa, as that one without coating may overheat under heavy load. I've seen it done may times on performance gas engines, I don't see how it wouldn't benifit a diesel to keep the heat in the exhaust instead of the head and piston (especially if the engine isn't equipped with piston squirters).

Ceramic coat inside and outside the intercooler pipes so that they don't heat soak. My supra's intercooler pipes are bare aluminum and remain scalding hot for loooooooong after the car's shut down. A friend of mine has his ceramic coated, you can touch them while the engine's running just after a lap of a road course.

A water/air IC may be prime in this application if engine cooling is a serious issue and engine bay space is tight... you can remote mount the water system's radiator and leave more incoming air to cool the engine's radiator, as opposed to having an air to air IC and blowing the cool incoming air over the smoking hot IC then onto the even hotter radiator. Water/air IC's are also more compact and don't require any airflow to the inlet air's exchanger. They're not used often in road cars because air/air IC's have a higher horsepower potential and are more efficient at the high speeds a road car usually travels at. Most water/air IC's have limits around 500hp.

Anyway, on the assumption that this is a Toyota turbo you're using, CT12, 12A, 20, or 26 based, there's alot of highflow turbo elbows and downpipes available, as that the former came on the 1JZ-GTE, the 2JZ-GTE, the 3S-GTE/22R-TE, and the 7M-GTE. The turbo you have will have the model number stamped on the compressor section, but I honestly have no idea what it would have

I don't know if the EGT thing was figured out, but anyway, lowering your EGT doesn't have much, if any, effect on spool time or boost threshold for a turbo. It does however make the turbo last substantially longer because the center section sees less heat, the turbine section retains less heat, oil isn't as likely to coke in the passages and bearings, and it helps keep the seals lasting long and running strong. Lower exhaust gas tempratures are good for pretty much everything if the engine's tuning and performance are maintained. Cooking a turbo to death with exhaust gases unneccesarily 200*F higher than they could be is just wasting money and horsepower.

Anyway, I hope this helps in some way. Good day to you.

 

[FJn00b]

I did some temp test on my 3B turbocharged which comes with a top intercooler and the difference between the outside air temp and the turbo air temp at 3B intake manifold with @ 5 PSI pressure was about 2.5 degree C to 4.0 degree C.

This differential air temp stayed the same up 8000 feet of elevation

 

[Christian]

Thanks alot Keros, a lot of what you have written have betouched upon. But I will look in to the turbo elbow and heat protection. If you have any leads on the elbow please let me know!

FJn00b, its funny that you mention the 3B, my girlfriend and I looked at a BJ42 for her, instead of the 3 year old VW Polo she drives, just an hour ago! It had a bog-standard B3... Good to hear the intercooler works!

I have bought the PWR kit, it should be in the mail tomorrow!

 

[Toyo Boyo]

Hi Christian,

I fitted an air to air intercooler to my Surf, fitted with a 2LT-E. I didn't get any more technical than fitting an intercooler off another 2.5 litre turbo diesel (Mitsi L200). I just worked on the fact that some clever Mitsubishi engineer had already done the calculations for me!

A couple of friends have done similar mods and fitted small cooling fans under the cooler - the L200 actually comes with one fitted

Easy to do and noticeable power gain. See here for my write up Intercooling

also - Performance Modifications for some more ideas.

If you go for a water-air intercooler, rig it up with its own self contained water supply so if it fails it won't cause any issues to your engine.

There was a comment about the frontal area of the rig earlier in the thread. I wouldn't worry about it - within reason - at the speeds your rig will be doing it won't be much of an issue.

Good luck with the build - it looks great - portal axles what joy!!!

 

[Christian]

Easy to do and noticeable power gain. See here for my write up Intercooling

also - Performance Modifications for some more ideas.

If you go for a water-air intercooler, rig it up with its own self contained water supply so if it fails it won't cause any issues to your engine.

There was a comment about the frontal area of the rig earlier in the thread. I wouldn't worry about it - within reason - at the speeds your rig will be doing it won't be much of an issue.

Good luck with the build - it looks great - portal axles what joy!!!

Thanks! It will have ints own water system. I have read your write-up more than once I have done a lot of research on the subject and your write-up popped up. It looks good!

something like that would not work on ours beacuse of the engine location and all that. And I have bought the PWR kit, so...

Of course we have to keep an eye on cooling, but I agree with you, and yes, Portals, if for noting else, then just for having it!

 

[Keros]

There's an outfit called SupraSport that has batches of CT26 turbo elbows manufactured occasionally, they are bolt-on replacements for the 7M-GTE's elbow. That said, they are a cast iron piece that flows quite nicely compared to the stock elbow. It's know as a LIPP Turbo Elbow, I think. I occasionally see a them pop up used, but admittedly, a custom fabricated downpipe is lighter, cheaper, and more readily available.

Unfortunately I don't follow Supra tuning outside North America, so I don't know who would be handier to you. Regardless, if it is a CT26 turbo you're working with, perhaps a chap named Randy at BIC Performance could make you a DDP section that would suit: BIC Performance Home
In any case, you could make your own DDP with a flange cut to mate to the back of your turbo.

 

[Dougal]

1KZ's use a CT12B.

Christian, I have the chassis number from a 2004 120 series powered by a 1KZ-TE. I'll PM it to you later. This will let you get the part number for the genuine later heads.