would this work?

Cartman · 09-10-2006, 10:41 AM

Thinking about doing up a homebrew twins setup. I would use my existing HX35/40 as the small turbo and I'm unsure about the top turbo.
Will this work with an unwastegated housing? It's got the 14cm2.
I'm looking for something that will clean up the smoke from the fuel I'm throwing at it (check my sig) things get REAL warm right now
this forum rocks!

Trapper · 09-10-2006, 05:46 PM

Yep your 35/40 would work, I know their is someone around here that has one with a B2. I'm hoping to do a set of twins with my PhatShaft 64, well see I really need a different manifold.

gwhammy · 09-10-2006, 08:28 PM

Back pressure might hurt you without a wastegate on it and it might overspool the small turbo. You need something to bypass the extra volume around the little one.

joektsi · 09-10-2006, 10:55 PM

I am starting a project all most the same, but i will use a cheap waste gate off ebay, i have seen it done before. It may be more work to plumb one in but it is a little cheaper and you don't have to worry about the stock gate being to small

HOTMOPR · 09-11-2006, 01:35 AM

check my garage I have a 35/40 over a HT3B with a non wastegated 16 and two external gates. It works well.. I do think a 14 on the hx would work better but they are different.
P.s I built it all my self, So I am sure anyone can do it!!

Cartman · 09-11-2006, 06:28 PM

What kind of EGTs do you see with your current setup hotmopar?
I realize I have a 215 pump and it will be different but I was hoping for a baseline.
What kind of HP do you think I can expect to make with an identical setup?
I remember reading somewhere that nobody liked using a stock turbo because the wastegate was too restrictive...do the external aftermarket ones solve this issue?
PS I dig the valve cover breathers

***got...DIESEL?*** · 09-11-2006, 10:45 PM

I'm not even using a hybrid yet on top, but I did heavily modify the turbine housing and gate as well. I'm gonna dyno in 6 weeks when I hit the road before I make any more changes to the top turbo. I have an internal 40 mm gate, and at 70 psi, my drive pressure is 70 or a little less. I scratch 1400 on the pyro full tilt boogy without the meth on, but remember with horsepower comes temperature. You're just not going to get 1200 and high horsepower both. It's a towing mother as well, and EGT's never go above 1100...but I'm not burying the loud pedal either as there is no need, but I can still out accelerate anyone else....even if they're empty LOL.

Moral of the story is yes the stock turbo will work fine as a secondary, but without some gate mods or an external, drive pressures may get high unless you go above a 14cm^2.....and at this level of bombing you should be making sure all 6 holes get gated as well to keep drive pressures and temps equal. There's not as much room for error at higher power levels so take extra care there.

HOTMOPR · 09-12-2006, 12:37 AM

Quote:

Originally Posted by Cartman

What kind of EGTs do you see with your current setup hotmopar?
I realize I have a 215 pump and it will be different but I was hoping for a baseline.
What kind of HP do you think I can expect to make with an identical setup?
I remember reading somewhere that nobody liked using a stock turbo because the wastegate was too restrictive...do the external aftermarket ones solve this issue?
PS I dig the valve cover breathers

I will hit 1300 WOT but it cools to 1000-1100 quickly..
A big external gate will help more than the stocker..

gwhammy · 09-12-2006, 07:53 PM

With the bottom turbo unhooked and a 38mm tial wastegate I can hold boost on the hx35 to 21 lbs. under full fuel. I have almost the same setup on fuel and you do cartman. With 35 on top of a 3e it makes 60 but I think the small turbo is backing way off as the big turbo is in the low 30 lb. range. I think I might put boost to the top of the wastegate and start regulating the pressure up on it. Once you try twins you'll never go back to a single!

***got...DIESEL?*** · 09-13-2006, 03:32 PM

lets assume a 14.2 atmospheric pressure there in MO whammy.

21 psi little turbo = 14.2 + 21 / 14.2 = pressure ratio of 2.48

so.....

big charger oulet pressure of say 33

so....[(33 psig + 14.2 psia) x 2.48 pr] - 14.2 psia = 102.86 psig little turbo outlet pressure. So we are no where near this number eh? Becasue the variables assume a perfect temperature variable, which is near impossible to achieve in this application.

I bet your secondary isn't backing off of that 21 set point. What I DO bet is that the hot outlet air from that primary is ruining the efficiency of the secondary. There's a perfect example of the need to get the outlet temps down on the primary before second stage compression occurs. Didn't mean to hijack the thread.....just a convenient place to point out some interesting math, and make you guys think a little. STAGE INTERCOOLING!!!

Chris

WideOpenThrottl · 09-13-2006, 05:29 PM

It seems if I have the exact opposite problem most people have with twins, that is overdriving the little one, I seem to be overdriving the big one. I have a 40mm wastegate set up to bypass the 35/40, but have it blocked off. I am seeing 40+ psi when hammered coming out of the 3B, and only seeing about 55-60psi in the manifold. I know its not boost that matters, its getting more mass of air in, but just doesn't seem to work right, at least compared to what I've read. Seems like hooking the external wastegate back up would just cause more problems, anybody have any thoughts?
Tim.