New guy go easy on me

OK let's say your power peak is at 5,000 rpm (which would take a lot of doing) that means with the Cummins crappy head you would need about 500 cfm at 80% VE, so let's say you get it up to 90%, and you're at 600cfm. Divided by 2 and that means you need about 300 cfm or 21 lb/min of air per turbo. At a 4:1 pressure ratio, (45 -ish psi which isn't much for a diesel) here's where you are on a compressor map of a 74mm (inducer, not exducer, right?) Garrett turbo. Waaaaay off the map, and way into surge. Even if you did get this to work, it's clearly not an efficient turbo setup for the engine. just my $.02 I'll butt out now.

74mmmap.jpg
 
the great thing about diesels is you don't have fuel/air mixture on the compression stroke... just air... so you can cram a truckload of boost through those piss-poor ports and compress it 16-17 times and no worry of pre-ignition like a gasser

you can reach your power goals w/ a healthy single and some nitrous, but I think you'll enjoy the truck more overall with a compound setup
 
Don't mean to derail the thread but I was just wondering.....

Given that the Cummins in the most popular engine for highly modified competition,,,, why hasn't anyone made an aftermarket head that flows better??
 
so far your only option has been a ~$15k billet aluminum head w/ no water jackets...

but that's going to change soon hopefully
 
Turbo Performance said:
Because they run compounds. Running parallels like what you're talking effectively cuts motor size in half in regard to what each turbo is seeing. That makes spool pretty much impossible with the size of chargers you're talking.
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Exactly..... Smart and sells and awsome blanket (shameless plug for Levi LOL :cheer: )

unlimited1 said:
There little one is still larger than my two
What I have found is that the size of the exhaust side housing is alot larger than the housing on my two turbo there allmost half the size need to start treating the diesel like a gas engine with alot of compression
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You're thinking of this all wrong. Like Levi said, you are basicly putting a 74mm turbo(very big) on a 3.0L 3 cylinder do you really think thats ever gonna spool? Heck you would have trouble spooling an hx35 with a motor like that, let alont a 74 mm.
 
Lets actually sit down and go through the numbers....
Realistically you are looking at a volumetric efficiency in the .7-.8 range depending on how well you can get these truds to flow. If you could get a 5.9l to have a VE of 90% or more you would be have god status.

So lets begin: Wa = 800hp*18:1*.38/60 = 91.2 lb/min total

91.2/2 = 45.6 lb/min each

MAPreq = (45.6lb/min*639.6*(460+150*F))/(.80VE*(4500rpm/2)*180cuin) = 54.9psia

54.9psia/14.7 = 3.7 pressure ratio


Going by the map on this page for Bullseye's S476, 45.6lb/min at a PR of 3.7 is going to be WAAAYYY into surge.



The best turbos I could find to do this with is a GT3076R or an s258. But, you are still going to be pushing the edge on the PR of the turbos and walking a tight rope trying to operate that close to the surge line. None of Garrett's other turbos the flowed in that range were mapped for a PR that high, and good luck finding decent Borg Werner maps.
 
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It's 54.9psi ABOVE atmospheric, so you have to add that in

(54.9+14.7)/14.7 = 4.7
 
Forrest Nearing said:
the great thing about diesels is you don't have fuel/air mixture on the compression stroke... just air... so you can cram a truckload of boost through those piss-poor ports and compress it 16-17 times and no worry of pre-ignition like a gasser

you can reach your power goals w/ a healthy single and some nitrous, but I think you'll enjoy the truck more overall with a compound setup
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If Forrest is recommending twins, they have got the be the way to go for a setup.:hehe:

torqueofthetown said:
Don't mean to derail the thread but I was just wondering.....

Given that the Cummins in the most popular engine for highly modified competition,,,, why hasn't anyone made an aftermarket head that flows better??
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Scared to invest the money and not sell em.

Forrest Nearing said:
so far your only option has been a ~$15k billet aluminum head w/ no water jackets...

but that's going to change soon hopefully
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Very hopefully...
 
...and just to chime in, 0.38 BSFC is wildly optimistic for that sort of combination @ peak power. ;)
 
Big Thumper said:
...and just to chime in, 0.38 BSFC is wildly optimistic for that sort of combination @ peak power. ;)
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It probably is but since no one has been able to offer any numbers I've had to extrapolate that. Using a higher value would require more air for this, which would make it seem even more unlikely that there will be a turbo available.

Care to suggest a more accurate BSFC for a diesel?
 
Just finished milling the intake off and removed the valves could not believe that the runners were that bad
 
Now you can see why so many people run twins so they can cram in alot of air since the head doesnt flow.
 
Ya and it looks like the water jacket is super close inside the port not sure on how much to cut out Oh well we will just see
 
On the 3.08 thing....

Better have 8-10 extras laying around as they dont make the R&P for them anymore.

What are you doing about making both sides lock up? Lincoln locker? Huge slicks?

And you will run out of RPM with only having a 3 spd.
 
Well, I am assuming a 15" wheel also. Heck, stock600 had 4k rpms and ran out in the 1/8th...
 
oldestof11 said:
On the 3.08 thing....

Better have 8-10 extras laying around as they dont make the R&P for them anymore.

What are you doing about making both sides lock up? Lincoln locker? Huge slicks?

And you will run out of RPM with only having a 3 spd.
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9'' ford with 10.5w tires for the track the truck will have a 20x16 wheels for the street
 
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