Sequential Turbo Build

[hvguy]

After sitting around these past few days... I got to thinking... what if I could get a small turbo to spool up to about 15lbs on a 1st gear pull to redline... and have a bigger turbo already spooled to take over on the higher gears....

So after digging around on craigslist i found some poor chap who is selling a small garrett turbo that came off a 1.6L engine... PERFECT!

I plan to have it set to about 15 or so PSI, and have the bigger turbo set to UNLIMITED!

I plan to have a maximum boost pressure of about.... 35-40psi, intercooled with arp head studs and a OEM head gasket...

Any idea when the connecting rods bend? I believe I might just find out the hard way.
Since im on the topic of engine internals, does anybody know of a good racing rod to replace the stock ones with? After talking with jason about the stock bearings, ill probably just get some stock replacements to keep the engine somewhat happy during the many beatings it will have to endure.


Thoughts?

[Jason]

I was going to do the same thing, more for the wow factor. You need to look up how compound turbos work... How your thinking isn't how they work together. Your small turbo makes all the boost, the large turbo only pushes a few pounds of boost into the smaller one, as turbos multiply air pressure. The large turbo may only need to push 5 or 6lbs of boost into the little turbo to enable it to make huge boost. There are a couple problems though. Sounds like the small turbo is going to be too small (off a 1.6). The smaller turbo exhaust housing cant be too small or the drive pressure will be sky high. With the correct sized single turbo, you can make more boost that the engine can handle. It isn't like a cummins engine that can take 60lbs of boost. The head will just warp/push off the block, studs or not. (becuase its aluminum). 40psi is probably about all it will handle for a decent amount of time. The guys in Europe I talked to running 40ish lbs of boost end up with cracked heads, cracked pistons, etc after a while. Also, the stock fuel pump wont push enough fuel to even make that kind of boost, you will need a built pump with a larger 12mm head. The 10mm head will bring the engine to around 200hp. The stock internals are supposed to be good for up to around 300hp. Making lots of boost down low is what bends rods on these engines, they like to be up in the rpm before you make big power. As for rods, there are places in Europe that sell H-beam rods, though I don't have a link to any site you can order them from or anything. I have seen them in engine build pictures, there was actually a picture in a thread here somewhere. It was in another language so that made it hard to figure out where the rods were comming from. I have never seen a set for sale here on ebay or anything like that. You might check over on vwdiesel.net and see if someone over there knows who you can get a set through. I didn't look into it as its out of my budget.

Not knocking your effort at all here... The compound turbos would be cool as hell, I just don't want you to get your hopes way up and come to find out after all that work that the engine doesn't make much more power or boost!

Jason

[hvguy]

I was going to do the same thing, more for the wow factor. You need to look up how compound turbos work... How your thinking isn't how they work together. Your small turbo makes all the boost, the large turbo only pushes a few pounds of boost into the smaller one, as turbos multiply air pressure. The large turbo may only need to push 5 or 6lbs of boost into the little turbo to enable it to make huge boost. There are a couple problems though. Sounds like the small turbo is going to be too small (off a 1.6). The smaller turbo exhaust housing cant be too small or the drive pressure will be sky high. With the correct sized single turbo, you can make more boost that the engine can handle. It isn't like a cummins engine that can take 60lbs of boost. The head will just warp/push off the block, studs or not. (becuase its aluminum). 40psi is probably about all it will handle for a decent amount of time. The guys in Europe I talked to running 40ish lbs of boost end up with cracked heads, cracked pistons, etc after a while. Also, the stock fuel pump wont push enough fuel to even make that kind of boost, you will need a built pump with a larger 12mm head. The 10mm head will bring the engine to around 200hp. The stock internals are supposed to be good for up to around 300hp. Making lots of boost down low is what bends rods on these engines, they like to be up in the rpm before you make big power. As for rods, there are places in Europe that sell H-beam rods, though I don't have a link to any site you can order them from or anything. I have seen them in engine build pictures, there was actually a picture in a thread here somewhere. It was in another language so that made it hard to figure out where the rods were comming from. I have never seen a set for sale here on ebay or anything like that. You might check over on vwdiesel.net and see if someone over there knows who you can get a set through. I didn't look into it as its out of my budget.

Not knocking your effort at all here... The compound turbos would be cool as hell, I just don't want you to get your hopes way up and come to find out after all that work that the engine doesn't make much more power or boost!

Jason
i see what your saying.... it sounds like In this case I have a perfect turbo for my application... since it pretty much maxes out my gauge at 35psi...

I might just stick with stock....

although I do have this BIG! turbo... but I doubt it would even spin lol... >.>.......<.< or will it?

As for the oil pump.... any idea if it can handle the extra 2 turbos?

heres what I had in mind:
http://i45.tinypic.com/257gak2.jpg
http://i45.tinypic.com/b516pg.jpg
http://i49.tinypic.com/4ufexc.jpg
here it is sitting on a 13" wheel
http://i46.tinypic.com/bj6ced.jpg

[Jason]

No fucking way... lol


Jason

[Slobodan]

FUCK! The Fuck is that??? DAMN dude.... If you bolt that on, It was only work as a scavenge pump MAYBE half a pound of boost. Where did that come from? And where can I get one?

[hvguy]

FUCK! The Fuck is that??? DAMN dude.... If you bolt that on, It was only work as a scavenge pump MAYBE half a pound of boost. Where did that come from? And where can I get one?

lol, its a..... big turbo, i was at the scrap yard selling some metals and noticed it in one of the bins... i offered to buy it, and they raped me on the price =(

Its a model VT60? i was thinking of putting it on my 12 valve cummins.... but it spins the wrong way =(

you can buy this one =) it has ZERO! shaft play in ALL directions! excellent condition.

[Ruby Rhod]

but it spins the wrong way

So?Turbo rotation has no relation to engine operation.

[Jason]

I think he means the compressor housings are oriented in the wrong direction to mount up to the engine..

Jason

[hvguy]

I think he means the compressor housings are oriented in the wrong direction to mount up to the engine..

Jason

exactly what I mean.

Prob gonna stick with the setup I have now... plus an intercooler and work on keeping the engine cold with the new radiator..

this will be put on the back burner for now

[VolvoForLife!]

Sequential turbos require a computer to control, it can't be done manually or mechanically.

[IceV_760]

Compound setup aint not bad at all. I have been planning it just to some car, and know kind a lot about it.
Firstly, pressure didnt multiply. It gives even more.
You calculate it this way:

20psi = (20psi+14.7psi)/(14.7psi) = 2.36 PR. So, that is pressure ratio on turbo, you calculate how much boost you want it gives, and add air pressure to it

2.36 PR x 2.36 PR = 5.57 PR. So, we have two turbos which will boost same amount, now just do the math

5.57-1 = Relative PR = 4.57. From that 5.57 PR you minus air pressure 1, and get the boost.

4.57 PR = 67psi. You see now, you dont multiply it, its over three times more by that "setup".

As a second turbo, which is on exh. mani, stock can be used. Bigger exhaust A/R recommended tho.

And then, how you calculate correct size where to look the big turbo?

Lets go for it.

D24TIC, 2.4 liters engine. OEM turbo is Garrett t03. And we want final boost to be, lets say 2.5bar, which is same as 3.5 Pressure Ratio, PR.
Engine revs will be 5´000.

So, displacement 2.4ltr x PR 3.5 x revs 5000= 42´000

Second part goes little to " i quess" side on some parts, but anyways, lets do it.
There you pic some bigger engine as compartment engine. "Just pulling some numbers from my hat."
What numbers we want then? Revs from big engine, and PR. So we downsize revs from d24tic some, and pic roughly normal PR from bigger engine.
Big engine will have PR of 2.2 ( 1.2bar boost) and will rev up to 4'500rpm.

So. 42´000 ( what we calculated correctly just minute ago) : big engines PR 2.2 : big engines revs 4500 = 4.2424.

So, engine where we start to look correct big turbo, has roughtly displacement of 4.2 litres. Search car with displacement of around 4.0-4.5 litres,
and search what turbo it uses.

I have far more longer done plans, but i dont want to
tell everything now. Just wanted to give some help to calculate what you may be planning to do. And at it is possible.
Here in finland we have few compound-charged diesels, atleast one toyota and few MB's as far as i know.

PS. Compound setup dont require any electricity to control it, you control it with wastegates. YOU will figure out how ;)