Contour Enthusiasts Group Archives Forums Modifications Forced Induction Did he say twin turbo?

1. This thread has turned into a pissing contest, if it doesn't turn around, I'll lock it.

2. Travis, you've thrown out some crap and have made no attempt to defend it technically, only proceeded to start a pissing match with the forum regulars. I consider this trolling, and that puts you on thin ice. Get back on topic, and bring more tech than flawed assumptions, or go away.

3. Stazi, just let it go. Stick to the tech.

My roomate has an S4. 2.7L TT. Turbo's are TINY ont he thing. But you wanna talk about a small engine bay, look at one of those

and one other thing, Travis, my four year old nephew has better spelling and grammar than you do; this makes you look like foolish, and makes anything you post less believable regardless of what it is. I suggest making an effort to making your posts a bit more readable if you wish to be taken more seriously. But of course, actual tech is a pre-requisite before that will help anyway.

Ok yes lets go back to the tech and ill try harder to become more clear in what im saying.

Ok regaurdless of whether you can package it or not lets talk about the ability of the seperate systems to make power.

This is my argument for 2 turbo`s.

Advantages:
The turbo headers are easier to make

By using 2 turbo`s exhaust header manifold design is improved. Because heat loss is kept low. Therefore the boost threshold is lower with the same a/r.

By the additional improvement in exhaust header manifold design a higher a/r can be used while maintaining the boost threshold at its current level which causes less tip.

In theory This will produce more power by allowing more radical cams and port work without reversion becoming a problem.

My argument for the exducer bore is made by this math work I completed.

Showing at 750 cfm (2) 2 inch pipes will see 286 ft per second gas velocitiy.

It would take a 2 and 7/8 inch ID pipe to flow the same amount of air at a slightly lower velocity 277 ft per second.

So the exducer bore on a single turbo would have to be quite large to flow the same amount with the same amount of pressure drop as the 2 smaller turbo`s.

Disadvantages

Cost if you go with new turbo`s

Sizing 2 turbo`s appropriatly for the application could be hard.

Extra complexity at controlling wastegates and making sure water/oiling lines get to where they are suppose to go.

Extra intake pipes and intercooler piping and intercooler modifications.

Single turbo:
Advantages

Simple

Cheaper

Would be very close to 2 turbo`s in performance *debatable

You can use a huge turbo I mapped out and found a t70 would work last night if you were going after like 25 pounds of boost
So bus turbo`s from junkyards are fair play here and that means cheap.

Disadvantages

Debatibly you could drag out more power from a twin turbo system.

Header is hard to make and has more areas that could fail. Its also less efficient. There is alot more surface area and bends before the turbo to cause heatloss and turbulence.

Turbo sizing on this side of the scale could be hard to get just right depending on desired rpm range.

You would have to use a large expensive external waste gate for that much flow which is harder to control then 2 smaller wastegates. So low speed could be more of a hassle.

I also done some numbers on compressor maps and for a high output 3 l running 22 psi I came up with these numbers


T66 (best matched compressor)

70% @ 7300 139 c* after turbo
76% @ 6000 129 c
76% @ 5000 129 c
74% @ 4500 132 c

Compared to the closest compressor for a twin turbo setup

T-3 60 series trim

69% @ 7300 140* (at the high end of compressor map)
73% @ 6000 134*
70% @ 5000 139*
67% @ 4500 144* (surge line)

Through the testing range of the engine they both would be pretty much the same with an intercooler.
With less boost pressure for street driving the dual turbo efficiency goes up as it drops more towards the center of the graph and the t66 goes down as it drops towards the bottem of the graph.
So the twin turbo would have a couple horsepower through the midrange over the single turbo from a stand point of just compressor maps and the single would have it in top end.

The twin turbo`s have a maximum combined flow of 62 pounds of air and the the t66 has a much higher 72 pounds of air

You could debatibly go with the t64 its smaller and would offer more midrange but top end efficiency wouldnt be as high. A trade off between the 2.

This is only on the compressor side though. My previous statement stands.

So the twin turbo setup would give you hotter temps through the topend. The single hotter temps through the midrange.

Id also like to add that beyond 22 psi there is not a good match through standard compressor maps for the twin turbo setup. Where as the the t66 has alot of room to grow. About 5 more psi across the board.
2 gt 32`s with a 52 trim would be better then Any of them by far. But who has 6000 dollars for 2 turbos?

Oh man, where to start . . . At the beginning I suppose . . .

Quote:

---

Ok regaurdless of whether you can package it or not

---

you don't seem to get it do you? This right here is the crux of the matter. The whole context here is turbocharger(s) applied to the duratec engine in the CDW27 platform.
There is no place to put the second turbo, plain and simple. Let's pretend you find a place anyway after relocating or removing all sorts of stuff, its still not gonna be in a place that allows you to run decent exhaust manifolds (ie short).

Quote:

---

lets talk about the ability of the seperate systems to make power.

---

First, this argument is inane (yes that is spelled correctly, go look it up) because both layouts can be made to make equivalent power on this size engine, it is all in proper sizing for the application and proper tuning. Minor efficiency differences can even be accomodated for.

Hmm, I actually had responded to a bunch of your stuff, and ended up deleting it just now, becuase I realized that beyond what I said above, I kept saying the same thing; Virtually everything you say is contingent upon some pretty big assumptions about the package and the setup, most of which don't even apply in the case of the contour. You keep forgetting that this is a discussion about fitting a turbo or turbos to a Contour not a general single vs. twin discussion; I already responded previously with my general views on twin vs. single.

On to your second recent post, you compare a single vs. a twin with specific turbos.

First:

Quote:

---

high output 3 l running 22 psi

---

You do realize that this sort of setup would potentially be in the neighborhood of ~500hp at the crank? Not exactly the sort of power that could be handled by a contour transmission or chassis. Plus if someone has the cash to be dumping into a duratec to get to those levels reliably, do you really think its going to be in a FWD contour????? Let's try to be at least remotely realistic. But then again, you obviously have sized this stuff in search of the dyno queen of the year award.

Second, your "match" of a T66 compressor is ridiculous, anything under 4500-5000rpm rides the surge limit; I don't know much about you, but eating the compressor wheel because of constant surge doesn't sound fun to me. This also points to your poor choice of a 60 trim T3 for the twin setup, another serious surge problem.

So first, you choose an output level that no available transmission or chassis can support safely, and the engine block is even unknown at that level; and this even all assumes a complete rebuild using all forged internals and a custom forged crank. Second, you size everything such that it would be nothing but a dyno queen, certainly not something I would consider fun.

Peak Power is not the only thing that one should worry about on a street car.

Hey guys, I've been gone for a couple of days, what did I miss? And why is there urine all over the floor?

please lock Rara, this ain't worth anybody's time. . .

though fun to read, just drivel. . .that is, what he writes, i take what you and the staz miester write to the highest. . .(as expected). . .