Daves Compound Twin turbo XUD

[Dave]

for the bine haha

[samass]

Hahaha nice! You not worried about gas velocity being a bit low?

[Dave]

Indeed I am, but can only try. Everything can be enlarged at a later date its just more difficult to do the main manifold, found a 3 inch prop shaft and cut it up seems to have worked well as its quite abut thicker than exhaust pipe.

[samass]

LOL! Prop shaft!

even more pikey than mine hahahaha looks good tho, take you long to chop it all up and line it up to weld?

[Dum-Dum]

looking good mate

[Poodle]

Like the idea of the propshaft for material, might just have to steal that if you don't mind.

[Dave]

This was cutting up said prop shaft, taken months ago mind! Me and Ben (Xud Missile) and his friend Sam were at a scrapyard and I was scavaging and Sam suggested it, and low and behold there was one at my foot already taken off a lorry Took it back to the shop and began work.

[dturbine]

This threads full of win. Love how stock the car looks compared to how it moves in every fettle of tune. Must feel like its swallowing the horizon stepping on the throttle!

[Dave]

Should be going in, in the next few days...

that is all

[ozonehostile]

very interested to see the results of the new turbo, its pretty much the same size as mine

[Pompey306mark]

Turbo's you mean.

[Dave]

Notice track stack

[ozonehostile]

Well jel of your clean block, xud's look so much better painted

[Dave]

Wont stay like that for like I can assure you haha!

[strictly_perv]

Good work Dave. I can't help but wonder why the original turbo-IC pipe is still there though....

[ozonehostile]

Wont stay like that for like I can assure you haha!

Mayaswel drill some big holes in the sides and pour a couple of liters of oil over it now then haha

[Dave]

Good work Dave. I can't help but wonder why the original turbo-IC pipe is still there though....

That blowers off one of these... its not gonna spool itself

[Sambarker]

Good work Dave. I can't help but wonder why the original turbo-IC pipe is still there though....

Because topmount

[ozonehostile]

truck turbos are commonly known to be ftmfw

[mr_fish]

that down pipe....A-W-E-S-O-M-E

shouldn't of thought you'll encounter any rust issues!

[zx_volcane]

First start can't be far off! Nice work Dave

Notice track stack

[Dave]

Now in and running the engine in low boost...



Had my mate Sam help me fit big ass welding cable for the boot mounted battery (hence him being on floor! :p )



Starts as easy as pie, never had anything start that easy before... slight weep from passenger side driveshaft, nothing couple of hours wont fix.

Needs alot of fettling to to make the most of the air thats on offer, mainly the piping/pump. Just going to use it as a daily low booster to run things in, make sure there are no issues before I go for big boost...

[Tom]

That is amazing.

[Chris_90]

How does that set up work with 2 turbos? Is the air from the first turbo going straight in to the big turbo to spin it up??

Great work carnt wait to see how it goes when it's all turned up should be mega

[Tom]

Looks like it ^^

What turbo is down the back then? Is it a vnt or just a tiny standard one?

[Poodle]

No, the big turbo feeds the little turbo. Little turbo boosts up first, once that's going it effectively creates more exhaust gas - enough to spool the bigger turbo.

The best bit is when the bigger turbo comes on blow, it's not exactly what you'd expect. Two turbos boosting at 15psi makes 30psi right? Wrong. The little turbo is now compressing air that's already compressed, this creates super-awesome boost (technical term). With one blowing into the other they "compound" their pressure ratios and produce more boost than their individual capabilities added together. Say both turbos individually boost at ~2bar absolute pressure (absolute pressure = boost pressure + atmospheric pressure; ie what we know as 15psi of boost), expressed as a ratio to atmospheric pressure this is 2:1. So we have two turbos compounding their pressure ratios of 2:1 each, multiply the ratios together and we get a final pressure ratio of 4:1. Knock off a bar to account for atmospheric pressure and you're left with 3bar or 45psi of boost...

[Pompey306mark]

I really want to do this. Good work mate.

[Chris_90]

No, the big turbo feeds the little turbo. Little turbo boosts up first, once that's going it effectively creates more exhaust gas - enough to spool the bigger turbo.

The best bit is when the bigger turbo comes on blow, it's not exactly what you'd expect. Two turbos boosting at 15psi makes 30psi right? Wrong. The little turbo is now compressing air that's already compressed, this creates super-awesome boost (technical term). With one blowing into the other they "compound" their pressure ratios and produce more boost than their individual capabilities added together. Say both turbos individually boost at ~2bar absolute pressure (absolute pressure = boost pressure + atmospheric pressure; ie what we know as 15psi of boost), expressed as a ratio to atmospheric pressure this is 2:1. So we have two turbos compounding their pressure ratios of 2:1 each, multiply the ratios together and we get a final pressure ratio of 4:1. Knock off a bar to account for atmospheric pressure and you're left with 3bar or 45psi of boost...

That went straight over the top of my head , but the 45psi bit sounds like trouble lol

[darrenjlobb]

Knock off a bar to account for atmospheric pressure and you're left with 3bar or 45psi of boost...

Or more, my previous compound setup would see 60psi quite happily all day long, depends on your blower arrangement of course.

As already said on phone, great to see it back together, cant wait for some tuning!

[Dave]

stupid page bug

---

Cheers for the comments guy,

I guess I should state that it is actually twin turbo, in a compound turbo setup.

I have a big VNT blower down the back (which i've had on for about 2 years now), but now coupled with an old lorry turbo. This has all been massively inspired by darrenjlobb's twin turbo monster build obviously, and he's helped me understand how they both run together, so credit to him here!




The VNT blower and manifold has been unmodified, I've just moved the exhaust upto the gearbox, and fixed another turbo to the end of that. The compressor obviously feeds the vnt at the back, and the outlet of the lorry turbo heads down towards my exhaust. It's all working rather well so far, but so much tweaking to do with regards to MBC's, vane control, and pump control!



Engines only done 73 miles, so its all bedding in on a nice 14lb, and then slightly more when the larger blower wakes up, but pump needs some major fettling too, but the theory, and equipment is there for some epic power, clutch, rods, turbos, head bolts, modified head etc!