IDI.... compound turbos?

[Skii]

Okay gents, gathering a general consensus here. So some of you may have heard me talking about my old truck, the 88 IDI I've been tinkering with. Complete engine overhaul, transmission overhaul, and turbo rebuild.

Well I've come to a point due to my factory IP taking a **** after the rebuild. So what would a natural diesel head do? Slap a bigger IP on of course. So I hit up the guys at R&D IDI and got a hold of one of their RD150 injection pumps.... you know, the one just shy of the racing version..... after collaboration with their brains justin, we've came to conclude that my 5 year old banks sidewinder turbo kit is simply not going to move enough air to keep this beast happy. So, again, natural diesel head says ok, bigger turbo time.

Manage to get my hands on a borg warner B3 turbo, non wastegated, with a 62 mm inducer and 96mm exducer on intake side out of a freightliner with a DD15. After thinking, that turbo meant for a 12 plus liter engine was gonna have HELLA time trying to spool off my little old 7.4. So .... since I still have the te06h from my banks kit, and its you know, completely rebuilt..... whats stopping me from running a compound setup? B3 feeding the little Mitsu? R&D seems to think i have the engine built to handle over 50psi.... but what can this little mitsu handle?

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[Thewespaul]

That b3 won’t spool on the street without shutting down a highway with smoke just trying to pass a minivan. It would work in a race application like what that pump is meant for but it would still be a challenge to spool on the strip even with feeding it the bottle and the inducer size is a really poor matchup for a compound setup. As for the sidewinder, well get a drive pressure gauge and keep it under 3:1 and you should be fine, but I don’t think that’s possible with that setup. Good luck

 

[Skii]

The goal was to shut down the highways and the minivans.... that's the best part

 

[Thewespaul]

If you just want to make smoke then just run that pump with the sidewinder as a single. The truck will be faster with just the sidewinder than with those turbos in a compound setup.

 

[Skii]

Not talking about a twin turbo set up either. I think you've confused twin turbo with a compound system, in series, with a big low pressure turbo and a small high pressure turbo which effectively compounds the boost

 

[Thewespaul]

I know how a compound setup works, that large charger will be a restriction to flow until it gets spooled, so it will kill power until it lights. I’m not trying to dissuade you from trying compounds but you really need a better large charger, not just the cheapest turbo on Craigslist. An s369 or s366 would be much much better for you.

 

[Macrobb]

An S360 with .63 housing by itself is good for 25 psi and probably enough for the 150 pump. It doesn't take that much boost to burn that (relatively small) amount of fuel. I see no reason you couldn't do something similar with a s362 or S366, just make sure you use a really tight housing for responsiveness - you can always do a wastegate to lower boost/restriction at high revs;

 

[Chemgrad]

Check out Power Driven Diesels Youtube channel. They deal mostly with Cummins but they have done a ton of testing on various turbo setups single and compound I believe, might be wrong on the later, and they truly understand how to get the most power out of a diesel without turning money into black smoke and shorter engine life.

https://www.youtube.com/channel/UCpcor2FrquP_vAY6ltwTPOA

 

[79jasper]

A properly sized single will make more power, more efficiently, and faster than a twin or compound setup.
Look at 6.4 powerstroke owners building high power. They go to a single.

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[Skii]

So did Caterpillar with the c15. Acert v non acert

 

[Thewespaul]

I would say a properly made compound setup will be more responsive than a big single, but for our trucks it’s unproven, the large singles I’ve put on some IDIs have been very laggy.

 

[Macrobb]

You need a really tight housing(less than .83 for a S360) to make a big single spool up nicely. Plain and simple. Just take whatever AR recommendation you have and go smaller on it.

 

[Thewespaul]

You need a really tight housing(less than .83 for a S360) to make a big single spool up nicely. Plain and simple. Just take whatever AR recommendation you have and go smaller on it.

I think that is fine for 25-30 psi but if I remember that turbo you used was a custom turbo and not an off the shelf turbo, so I almost wonder if there was just an issue with that turbo or if it was just setup poorly for your application because I’ve had luck with an s363 with an .91 ar and it’s pretty responsive. It’s just hard to compare a custom turbo’s performance and applying it to off the shelf turbos.

 

[hce]

I have no idea just thinking out loud
If one thinks of a turbo as tricking an engine into being bigger then it is,
how big of n/a diesel engine would it take to make the power of small turbocharged 7.3?
If the turbo 7.3 moves as much air as n/a 12.0L
In a compound system where the banks would be feed compressed air it should lower drive pressures, taking 6psi and making 18 psi, with only increasing boost 12psi. Meaning 18psi with drive pressures of 12.

 

[Macrobb]

I think that is fine for 25-30 psi but if I remember that turbo you used was a custom turbo and not an off the shelf turbo, so I almost wonder if there was just an issue with that turbo or if it was just setup poorly for your application because I’ve had luck with an s363 with an .91 ar and it’s pretty responsive. It’s just hard to compare a custom turbo’s performance and applying it to off the shelf turbos.

I Think it was an 'off the shelf' turbo according to the P/N - with the housing ceramic coated, and the exhaust housing might have been modified to fit a different output connector spec... other than that, everything matched what I read. And when I got my .63 housing off of some random website, I just bolted it on. No mods or anything.

I have no idea just thinking out loud
If one thinks of a turbo as tricking an engine into being bigger then it is,
how big of n/a diesel engine would it take to make the power of small turbocharged 7.3?
If the turbo 7.3 moves as much air as n/a 12.0L
In a compound system where the banks would be feed compressed air it should lower drive pressures, taking 6psi and making 18 psi, with only increasing boost 12psi. Meaning 18psi with drive pressures of 12.

This is called talking in terms of airflow. That is, lbs/min of air(mass). This is what turbos are rated in, and power can be calculated from that at a given air/fuel ratio. Then you can back-calculate what PSI you need(at what temperature) based on the lbs/min of air mass flow you need.