• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Sequential turbos... do-able?

i thought the point of compound turbos is to spool up quicker without getting rid of the larger turbo. allows you to have good performance on the top end and good low end power too. something big single trubos do not offer
 
It can be, depending on the setup.

Some sequential setups are also done to split up the overall pressure ratio (boost) increase btwn 2 turbos. Believe Cat has some application(s) that use a 2 sequential setup to achieve a higher peak boost efficiency, than they could w/ a single turbo capable of that high boost level - while still retaining good efficiencies at the (less than peak) boost levels it runs the majority of the time.

While a given turbo compressor may be capable of operating in a wide range of pressure ratios (boost), say 0 - 30 psi, its efficiency will vary some at different pressures. So in a sequential setup, they might pair one turbo that's more efficient in the 0-15 psi range, w/ a second turbo that's more efficient in the 15 - 30 psi range.
 
SmithvilleD said:
Some sequential setups are also done to split up the overall pressure ratio (boost) increase btwn 2 turbos........
Click to expand...

This is actually an example of parallel turbos. Heath's LSR truck is a parallel set up. One tubo on each side both feeding the engine equally.

A sequential (or compound) twin setup uses a smaller turbo blowing through a larger turbo. The exhaust goes first through the small turbo then through the larger one and finally out through a single downpipe. The intake air also flows through one turbo then through the second and finally into the intake.

Maybe this will help clear up some confusion

http://en.wikipedia.org/wiki/Twin-turbo
 
No confusion, the Cat system is sequential.

http://honeywellbooster.com/turbocast/serial-sequential-dual-stage-turbocharging-technology/

Heath's LSR doesn't split the compressor duties btwn 2 different turbo's, with peak efficiencies at different pressure ratio's as I was talking about. Not certain where that ref comes from?

Upon looking closer at that Wiki page, it actually references the CAT ACERT engines I was referring to towards the bottom of the page under "Advantages in Diesel Emissions."
 
Last edited:
You are right, SmithvilleD. I stand corrected. I thought from your description that the CAT sounded like a parallel setup, but it is, in fact, a classic example of sequential twins. Thanks for the link to the vid. That helps to visualize what's going on for anyone who doesn't fully understand the concept.

The Heath set up is parallel. Two turbos equally sharing the work across the RPM range.
 
Last edited:
I haven't actually seen one, but I talk occasionally with a neighbor to our farm in IA that has a lot of construction equipment & stays up on Cat's latest technology.

Where in NW KS are you? I'd like to check out the Typhoon sometime.

I bought an AWD Eagle Talon new in '91 & built it to the point of low 11's on common street performance tires w/ no significant weight/options/comfort cutting. So I'm a fan of AWD turbo's practical street performance potential w/o sacrificing all the things that make a vehicle pleasant to daily drive.

Look at a GNX engine'd turbo TA, but the quality of the car itself, wasn't as impressive as that great engine.
 
I'm about 30 miles south of Goodland. I was in high school back in the early 90's so you can imagine how wished I could afford one of those beasts back then. Of course, with technology, today's cars are just as fast or faster. But that doesn't make me want one any less! Now days most people don't even know what a Typhoon(or syclone) is!
 
Had a friend that had a healthy Syclone. Bit lighter & less practical than a Typhoon, but that was one of the few vehicles around at the time that could compete w/ the Talon's 60 foot times on real-world practical street tires.

Yep, it was vehicles like those that got me hooked on experimenting with turbo's beyond the stock options. Had added M&W turbo kits to a few originally na diesel tractors, but how relatively easy is was taking an already reasonably quick, stock 200 hp AWD turbo car to a 400+ hp street sleeper was when I knew there actually WAS sometimes a replacement for displacement!

Then I matured (at least slightly) & recognized wrenching on an old diesel truck could be fun also & the truck has a fair bit of practical utility.
 
I have no factual information to contribute to this discussion, but my mind loves to play around with overcomplicated things like this. Its ramblings also included an idea about a small supercharger for the low end with a turbo for the top end. Probably a totally moronic idea if you start to look at it, but kinda fun also..

edit:
Here's a schematic of one twin turbo aplication I found..
opel_twinturbo_skisss_stor.jpg
 
Last edited:
thedole said:
I have no factual information to contribute to this discussion, but my mind loves to play around with overcomplicated things like this. Its ramblings also included an idea about a small supercharger for the low end with a turbo for the top end. Probably a totally moronic idea if you start to look at it, but kinda fun also..

edit:
Here's a schematic of one twin turbo aplication I found..
opel_twinturbo_skisss_stor.jpg
Click to expand...

Back in 2001 I drove a 4 cylinder diesel powered Opel passenger rental car from Geneva Switzerland to Venice Italy. Very nice engine. They should offer them here in the U.S.
 
I have an 84 opel that was meant to be a little more mileage friendly everyday drive then the 2500 truck. It hasn't been on the road since the hazardous trip from where I bought it with only the handbrake operational, as it was a bit more work then expected. Would love to have a tuned modern common rail diesel in that thing one day..
 
I was thinking about something like an eaton M-90 for an off road application where you would want instant boost off idle coupled with a turbo to make up for the M-90's in abilty to feed a 6.5 above 2000 RPM.

I seen a 6.9 in a Bronco that had twin M-90s and it got me to thinking.
 
Glad to see I'm not the only one having the supercharger/turbo combo idea, maybe it's not all that far fetched anyway. I guess it's all in the numbers if one takes a little time to look at it. I don't know how much airflow is needed at a certain desired power rating at a given rpm. Where the "crossover" to turbo operation need to be. And how the belt drive and air "plumbing" would work out. But if one had time/energy/funds to do such a thing it would've been fun just for the sake of having done it!
 
thedole said:
Glad to see I'm not the only one having the supercharger/turbo combo idea, maybe it's not all that far fetched anyway. I guess it's all in the numbers if one takes a little time to look at it. I don't know how much airflow is needed at a certain desired power rating at a given rpm. Where the "crossover" to turbo operation need to be. And how the belt drive and air "plumbing" would work out. But if one had time/energy/funds to do such a thing it would've been fun just for the sake of having done it!
Click to expand...

check out gatorsuperchagers
 
Woody35 said:
we need to get a engine design engineer on this forum
Click to expand...

I've got a good friend from college (mechanical design engineer major) that went to Garrett right out of school & has worked there ever since. I've showed him some of the turbo tech discussions & he'll tell me what he thinks/knows but shows little interest in joining/commenting on the forum.

Practically speaking, I interpret his limited interest as his method of time management. He's been doing it so long, that his patience for explaining some of the more complex stuff to folks confident in their beliefs (but still wrong in their understanding) is not what it was when we were younger.

Also spends plenty of time each day talking turbo, so he's not really actively seeking out additional turbo talk time.
 
You must log in or register to reply here.
Back
Top