LLY: my custom big twins build

[duratothemax]

I meant the back of the stock turbo, my bad.

I cut the flange off of a stock downpipe and then welded the 180* bend to it.

 

[Ridin'GMC]

Ah thanks! Hopefully your write up will help me alot with my twin setup in the future when I decide what turbo to use. BTW, I plan to ditch the factory fuel filter base setup and custom build my own fuel/water separator and another fuel filter, is there a parameter to delete the WIF sensor on EFI live? I do not have my own EFI live yet but running on Killerwhore's tuning. It's the only thing I got for now since I'm a budget builder.

Oh, I wanted your opinion on lift pump setup. I custom built mine, (I do not know if you saw mine over the DF) should I ditch the holley black pump and use 2 blue pumps as a dual lift pump setup or one pump should do the trick with 2 custom fuel filter bases as I plan to build later on. Just wanted your opinion. :thumb:

 

[Burn Down]

Awesome twin setup. I hope to build one of mine in the future.... Except I need to figure out if the turbos through my work is the right setup for the big charger (might use a turbo off the CAT 793D since they are designed to spool quickly but not sure if the vanes are the correct pitch to use as the big turbo). I love the VVT turbos and will continue to use the VVT with a twin setup.

Where did you get the flange to make the exhaust pipe from the stock turbo to the S480? I would like to know where to get the supplies for the flanges, I know where to get the piping though.

The 793D turbo is way to big to use for a twin with a stocker, if I remember right its 100 mm inducer. Have you picked up one of these chargers? The stupid thing weighs a ton, Cat put a cast iron compressor housing on. However it does have a nice machined compressor wheel. Not sure about the turbine dimensions, I quit looking at it after I changed a few.

 

[DMAXchris]

Subscribed. Great thread Ben. :thumb:

Hopefully this will be happening to my truck this summer.

 

[Ridin'GMC]

The 793D turbo is way to big to use for a twin with a stocker, if I remember right its 100 mm inducer. Have you picked up one of these chargers? The stupid thing weighs a ton, Cat put a cast iron compressor housing on. However it does have a nice machined compressor wheel. Not sure about the turbine dimensions, I quit looking at it after I changed a few.

I work on those engines, I rebuild them for a living. I guess I'll try looking for a smaller setup. The turbo weighs about 100 pounds, but they spool really quick and whistles insanely loud! It's not a whooshing noise but a pretty good whistle.

 

[LBZrcks]

I have a gauge ghetto-rigged in between the two turbos, its an old advance auto junk oil pressure gauge but I dont see why it wouldnt work...

I went out and tested it, it seems like the big turbo is making ~12psi or so MAX on my "big" tune...is that right? On the small tune it makes maybe 6-7-ish.

I will try to get a drive pressure gauge hooked up this weekend

just an update.

they are running very well. Spool up is VERY quick, thanks to that "stupid" VVT that simon was giving me shit about. The turbo exhaust braking using the VVT is very nice when towing as well.

I havent measured drive pressure, but EGT's never get above 1200* with a 2400us tune. (now simon before you snicker at 'baahaha you think 2400us is big', remember that I have big injectors)

Pressures between the two turbos are split basically 50/50. When im at 55psi, the big turbo is doing about 27psi, and on my stock tune (well stock, plus injectors) it will make 40psi overall, and the big turbo is going 20psi. If I drive it nicely on the highway at 68-70mph I can get 20mpg. But I never drive that slowly, so I usually get about 17.7-18 hand calculated.

The VVT also makes it very easy to control overall boost without having the need for an external wastegate.

My intercooler pipe broke at the weld a couple weeks ago so I need to redo that pipe. Now wait a second before someone comments on that. The weld/pipe that broke was the ONE weld that I didnt do. It was on the aluminum intercooler pipe; I dont have a tig so I had a local welding shop do it. But the pipe was a modified stock LLY pipe so it was tricky to get clean; I cant really blame the guy for it breaking. Im re-doing it with a regular mild steel intercooler pipe.

I also found out that 60psi is NOT the limit of what autometer Nexus gauges will read/register/record.....they will read up to the limit of the sensor (100psi I think?) and the gauge will register as such. I did a run with a pretty decent size tune and when I played back the run on the gauges and recalled my peaks I found I had hit 70psi.

I wont be doing that again...man I miss having a built motor...its ok though, the stock LBZ short block is stronger than my old built motor so Im not too worried.

This week I should have my new pipe done, its been too nice outside this weekend to be inside messing with the truck. Now off to do some water skiing! :joker:

ben

So was it just in the tuning to get more out of the 480 Ben?

 

[HogAssWild]

I was thinkin. About goin to a 480... or would it be more helpfull to upgrade the small charger 1st?

 

[scratchrob13]

Your unique Ben

You're