compound twin turbo's
 

Has anyone thought about doing some sort of compound twin turbo setup like they do on the diesel trucks. It looks like a really good idea to make a big turbo spool fast on a small motor. I was thinking of something like a IHI and a Hx35 on a z6. what do you guys think?


steve

Re: compound twin turbo's
 

:3

Re: compound twin turbo's
 

why the :3 ? Is there some thing that i am not seeing? peopl have done standard twins off of the same mani and made good power. why not use a big turbo that the motor would have a hard time spooling and a little turbo that would normoly run out of power combined to make big power together.

I was at a dyno day for diesels yesterday and some of the trucks with twins had huge primary turbos that they would never be able to spool normoly but ran with a smaller like stock turbo, they were able to spool both like stock. There were a couple truck making 900+wrhp and 1800+ lbft on just diesel with out nitrous.

steve

Re: compound twin turbo's
 

DO IT! and post the pictures!

Re: compound twin turbo's
 

bad idea all around on a car.

Re: compound twin turbo's
 

can you tell me why it is a bad idea?

Re: compound twin turbo's
 

you're dumb. exhaust from turbo 1 will not spool turbo 2 any faster. you have to use either the compressor out from turbo 1, or exhaust from turbo 1 along with compressor out from 1.

you can't ------- magically JDM some extra airflow from somewhere to spool 2 turbos

Re: compound twin turbo's
 

I have a Dodge turbo diesel and know how the stock turbo spools. A friend of mine has a super B turbo on his CTD and it takes longer to spool. Now another friend has Twins on his CTD and it spools like stock and it has a huge primary turbo. Don't give me ---- if you don't know what you are talking about. I just want to know if anyone on here has heard of someone using this on gas engine. why would this not work?



see pic

http://www.industrialinjection.com/s...-TWINS-102.gif

Re: compound twin turbo's
 

The reason those work well on diesels is the huge pressure ratios they need to run to make good power. On a gas engine that runs relatively low boost it just wouldn't work that well.

Re: compound twin turbo's
 

Complex...your brain is not very complex...Turbo one wouldn't spool turbo 2...TURBO ONE WOULD HELP INCREASE POWER AND RPM UNTIL EXHAUST FLOW WOULD HAVE ENOUGH CFM TO SPOOL NUMBER 2...Sequential turbo setups are common for Diesels because of their reliance on boost for all of their power, also because to handle the amount of boost that you would be forced to accomodate with that setup. Imagine, the first turbo would be a Chrysler conquest turbo(tiny), on a GSR motor with LS tranny. Second turbo would be a larger trim T4 or a GT35r. The long gears, somewhat large displacement and capacity for RPM, would allow you to spool the t25 by 2000 rpm and it would reach maximum efficientcy by 5000. The T4 would spool by 4000 easily and reach maximum efficientcy by redline, therefore creating a sequential setup....BUT the problem would be...once the t25 got maxed out it would spin too fast and eat ---- after 2 days. So it becomes more complex and not so easy to do espescially on a high reving monster like a honda...remember diesels rev to 3k...

Re: compound twin turbo's
 

Thanks for the reply. Some twin turbo setups on dodges use the stock HX35 with max efficientcy by 34psi and a larger turbo with max efficientcy at around 80-100psi. So you are telling me that the hx35 will only last a few days? Some of these cummins are rumming close to 5000rpms and 100psi of boost. If you saw the pic i am not talking about sequential turbos like on the rx7's.

Re: compound twin turbo's
 

there is a difference between compound & twin tubo set up.
here it is.

twin turbos use exhaust to drive both turbo at the same time.

compound set up uses exhaust to drive a primary turbo, then uses the
cold side to drive the secondary turbo which feed the engine.

as far as anyone trying this, i havent heard of it yet. most people just blurt out
the same answer as above, not actualy knowing the difference or not
knowing there is a difference in set up. and to answer your question as to,
can it be done? sure it could be done. whould ther be a better gain over a TT setup?
or even a single turbo? dont know, but it might be possible. you just have
to get the combination dead on.

Re: compound twin turbo's
 

Re: compound twin turbo's
 

The pictured setup is not one compressor side driving another exhaust side! Same manifold is driving both turbos.

Re: compound twin turbo's
 

If you look...the compressor out of the lower turbo is plumbed in to the intake side of the top one...that doesn't increase flow in the second really, it just needs to be linked through the same charge pipe so it goes through the larger turbo. Exhaust STILL drives both turbos...and...on the cummins, the first turbo would lose compression and bypass through a valve/flapper setup thats why it wouldn't spin to 5 gillion rpm and die in 2 days.

Re: compound twin turbo's
 

And...efficiency would need to meet in the middle...like small turbo would need to lose eff at a certain boost/RPM that is closer to redline, but it would be okay for it to start to taper off sooner.

Re: compound twin turbo's
 

In the compound setups the turbo is not "bypassed". Air is compressed by the first stage, then compressed again by the second stage, then typically intercooled. The first turbo is the "low" pressure turbo and the larger of the two. The second turbo is the smaller or (high pressure) turbo, then flows through the intercooler.

The compound setups allow the use of pressure ratios far above what a single centrifugal compressor of practical size can reach, and also allow very good response.

There is no flapper that bypasses the smaller turbo.

Re: compound twin turbo's
 

Depends on how the unit was setup, like I said if you are using similar trim turbines then you would be fine...BUT if there was a drastic difference in trim, you would overrun the maximum rpm of the smaller wheel. I've worked on many-a-cummins.

Re: compound twin turbo's
 

100% wrong. Both turbos are exhaust driven. The difference is that the smaller of the two is driven first. Then the output of that turbos exhaust drives the second larger turbo.

Now the secondary larger turbo's compressor feeds the primary smaller turbo. This is so that the first turbo is always working with out intake loss.

Now the way compounding works is that both turbos are set to have a pressure ratio of 2.5 or so. IT IS COMPOUNDING, meaning that you multiply them together to get the amount of boost going to the engine, so you have a pressure ratio of 6.25 (2.5 * 2.5). Boost seen by the engine will be (6.25 - 1) * 14.7 = 77psi.

Compressors are pressure multipliers, thats all.

The is the same effect as increasing the exducer size of the compressor wheel (lowering the trim). It moves the combined efficiency graph up and a little to the right giving you a slight increase in flow and retained efficiency at massive boost levels.

This technique is simply used to counteract the fact the turbos compressor is not very efficient at high pressure ratios.

Re: compound twin turbo's
 

Also, AERO you must be new and quoted that from another site...because you stated the obvious with most of your paragraph: "The first turbo is the "low" pressure turbo and the larger of the two. The second turbo is the smaller or (high pressure) turbo, then flows through the intercooler. [/color]

The compound setups allow the use of pressure ratios far above what a single centrifugal compressor of practical size can reach, and also allow very good response. "


LOL

Re: compound twin turbo's
 

Now the secondary larger turbo's compressor feeds the primary smaller turbo. This is so that the first turbo is always working with out intake loss.

Now the way compounding works is that both turbos are set to have a pressure ratio of 2.5 or so. IT IS COMPOUNDING, meaning that you multiply them together to get the amount of boost going to the engine, so you have a pressure ratio of 6.25 (2.5 * 2.5). Boost seen by the engine will be (6.25 - 1) * 14.7 = 77psi.



Now that is COMPOUND...he typed it before I did...That is the last of 3 twin styles and it is seen on larger displacment rigs!

Re: compound twin turbo's
 

Yup, and that is exactly what the setup is in the OPs picture.

Re: compound twin turbo's
 

Yes! I was trying to type out all the setups because some of these nogs are lacking gray matter...

Re: compound twin turbo's
 

I am relatively new to this site, but no quoting. It was only the textbook reason behind compounding. If it was that obvious you would not have added Or posted this.
Must be too complex for you, what does a sequential have anything to do with a compound setup? Backtracking anyone?

Madmax got it right, and you hang off his nuts? Nice

Re: compound twin turbo's
 

So if you know about this soo much then go ahead and do it and quit asking us. Get a ------- spine and do it if you feel it's gonna work. :3

Re: compound twin turbo's
 

coming to hmt as a noob with questions on something that doesn't pertain to hondas, and trying to adapt it to hondas, long story short, go ---- yourself

Re: compound twin turbo's
 

lol

Re: compound twin turbo's
 

Just because it is used on diesels does not mean that it can not be made to work on hondas or any other gas motor. I think that this would be a good way to not have tons of lag on a large turbo. Normaly this setup is used for high boost but it should still work well on lower boost like 10-15psi.

Re: compound twin turbo's
 

Compound setups are horrible on gasoline motors. Just the nature of there powerband already kills the idea. Coumpound setups don't give you any wider efficiency, which high rpm motors need. Compound setups simply give you efficiency at higher than normal boost levels.

This is why jet engines have multiple compressor stages. No one single compressor is gonna give you enough efficiency at massive pressure ratios.

Re: compound twin turbo's
 

Mad's right...There are a bunch of technical reasons why those systems don't work well on gasoline engines, especially with long wide powerbands. Diesel engines are anomalies for internal combustion.