Turbo gurus, have questions.

[TheAmazingDave]

Hello everyone. My name is David, and I have a problem. I'm a turbocharger n00b.

Now that that's out in the open, I have a serious question. As I said, I'm a turbo newbie. I had originally convinced myself that my supercharger would be enough, but it isn't. So I started buying parts for a turbo conversion. I bought a manifold from someone who custom makes them for my engine, but in a Corolla. I told him I need the manifold for a MR2, but it was essentially the same layout as a FWD Corolla. I got the manifold today. The build quality is great, but I'm a little sketched out on the position of the flange.

I was hoping that someone with turbo experience can let me know if this is a crappy design or not. I need to know if there are problems with running with the flange so far from center on a log style manifold. Does it pose problems with turbo spool or operation, or does it cause uneven backpressure in the different cylinders? Or perhaps both?

I'm sorry for sounding like an idiot. Any help is greatly appreciated. If this manifold is crap I want to scrap it and get one that will work.

Thanks again.

[TheAmazingDave]

I guess pictures of the manifold would help...

[canadam]

Every other turbo manifold I've seen says that the Corolla manifold won't fit the MR2.

Hopefully someone here can clarify for you.

[TheAmazingDave]

Thanks for the response.
I've got 2 Mk1 exhaust manifolds. If it came down to it, I could cut the head flange off of a Mk1 manifold and weld it to this one. I'm more concerned about the turbo flange placement at this point.

[canadam]

Sorry, I should have been more clear.

I wasn't talking about the head flange itself, It would be similar for all 4AGEs I would think. I just meant the shape/design of Corolla turbo manifolds doesn't usually fit MKIs, I'd assume because the position it puts the turbo in.

Originally Posted by 86mister2

Thanks for the response.
I've got 2 Mk1 exhaust manifolds. If it came down to it, I could cut the head flange off of a Mk1 manifold and weld it to this one. I'm more concerned about the turbo flange placement at this point.

[canadam]

Nice part BTW, what'd you pay for it ?

[TheAmazingDave]

Ah, gotcha. I see what you're saying.

I was holding this manifold in the engine bay above the stock manifold. I can see several issues I will have to work out. But there may be several pluses, too.

I can see that coolant and heater lines may have to be reworked, as well as a new route for the shift cables. But on the flip side, the position of the flange may let me keep the oil filter in the stock location as well as clear the A/C compressor. I'll know more once I have some time to poke around in the engine bay.

It was $215 shipped. Like I said it was welded well and I'd like to make it work if the design isn't detrimental(sp?).

[canadam]

I'll buy one of those if I ever come across a Corolla I want to turbo

[Coastal]

There are many manifolds for other cars that are off center like that.

Hopefully it clears the majority of your lines and parts..

Good luck with the project.

[dr3amr2]

Not really on topic about fitting issues, but was there a specific reason why was the turbo manifold a log type manifold?

[yoshimitsuspeed]

I am no manifold guru but I don't like the look of that mani at all. Of course equal length headers are optimal but not necessary but think of the pulse path on that thing.
The pulse from cyl 1 is going to want to travel down the pipe expanding into cyl 2 and 3 and the outlet. The rest of the pulse will travel up to cyl 4 and ricochet its self to death.
Cyl 2 pulse will hit that T some will try to travel toward cyl 1 some will want to bounce straight back into the cyl and some will try and bounce around toward the outlet.
Cyl 3 has a nice straight shot, it should shoot out of there like a lubed banana.
Cyl 4 well pretty much same as 1. Their aimed right at each other.
I don't know for sure how bad it is but from my understanding of fluid dynamics I think that would be a very inefficient mani.

It will still spool quick
it will still boost hard
But I wouldn't put it on my car.
JMHO

[Luni]

Log style manifolds kinda suck IMO.. Id have looked for something that was tubular and preferrably equal length. Log style manifolds have some design issues because the cylinders pulse seperately, and on a log manifold since it all collects together, it can cause minor reversion on the cylinders that arent firing. It can get detrimental the more boost and HP youre making with it. It can affect your VE in a negative way. Not necessarily enough to hurt you, but more so than on a seperate runner manifold (like whats on the 3SGTE).

What kind of turbo are you gonna put on it?

[TheAmazingDave]

Keep in mind, this is going to be my first turbo setup ever. I kinda figured it was a shitty manifold but decided that since it's my first time, I'm not ready to drop big bucks in high performance stuff. I value the advice you guys have given about the design, and your thoughts are pretty much mine aswell. If this setup works good and I come out of it with a running engine and not a paperweight, I'll begin to invest in better parts and a better setup.

I've talked to a few board members and I'm getting similar andwers. I plan on putting on a T3/T4 with a .48 turbine and .46 compressor. I've been told that will put me around where I want to be, ~15 psi on the street. I dont want to go too big because I'm used to the almost instant 14 psi of my supercharger, and off-the-line is something I don't want to sacrifice a lot of.

[yoshimitsuspeed]

Originally Posted by 86mister2

Keep in mind, this is going to be my first turbo setup ever. I kinda figured it was a shitty manifold but decided that since it's my first time, I'm not ready to drop big bucks in high performance stuff. I value the advice you guys have given about the design, and your thoughts are pretty much mine aswell. If this setup works good and I come out of it with a running engine and not a paperweight, I'll begin to invest in better parts and a better setup.

I've talked to a few board members and I'm getting similar andwers. I plan on putting on a T3/T4 with a .48 turbine and .46 compressor. I've been told that will put me around where I want to be, ~15 psi on the street. I dont want to go too big because I'm used to the almost instant 14 psi of my supercharger, and off-the-line is something I don't want to sacrifice a lot of.

I don't know if you can easily find those cheap or not but T25s are a dime a dozen in the DSM comunity. You can find them for $100-$150. Of course it also depends what flange you have on the mani.
I would think if cost was a concern you could find a better mani pretty cheap. Maybe used, or maybe not as pretty but more functional.
Or if you have acess to a welder you could make something or find someone to do it cheap.

[TheAmazingDave]

Everyone springs for a T25. I'm sure it's a great turbo, but I like all the available variety in T3, T3/T4 form. The manifold is welded to a T3 flange.

I'm prepared to spend about $500 on this Garrett T3/T4 I'm lookin at.

[Luni]

Dude a t3/t4 is pretty big for a little 1.6.. youre gonna have lag. Not to mention I doubt you will have fuel to run the thing to 15 psi.

I should ask, what kind of supporting mods do you have for a T3/T4? A T25 can make quite a bit of power on a 2 liter engine with 450cc injectors. What do you have to support a bigger turbo than that? Hell a T3/T4 46 is a bigger turbo than a CT20b and that turbo will damn near max out my fuel system on my 2 liter running 440s at about 15 psi... Just something to think about.

Any competant welder could swap that flange out for you if you need to. I think a T3/T4 is too big of a turbo if you dont want to sacrifice low end driveability on a 1.6.

Just my 2 psi.

[TheAmazingDave]

This engine is going to be ground up rebuilt before I put it into a car. It may not even be my current car as the SC hauls some pretty fat ass and I'm not in a hurry to loose that sweet blower whine. I'm thinking of getting another Mk1 for this turbo engine so it's gonna be one big ass project. I plan on renovating the fuel system and running a standalone EMS like megasquirt or something with MAP.

Bear with me since I'm a little slow with this turbo stuff. I'd like to run an external wastegate with a boost controller as I'm told this can really help with lag. Even though it's a bigger turbo, will it still lag badly to reach lower boost levels?

[yoshimitsuspeed]

Originally Posted by 86mister2

This engine is going to be ground up rebuilt before I put it into a car. It may not even be my current car as the SC hauls some pretty fat ass and I'm not in a hurry to loose that sweet blower whine. I'm thinking of getting another Mk1 for this turbo engine so it's gonna be one big ass project. I plan on renovating the fuel system and running a standalone EMS like megasquirt or something with MAP.

Bear with me since I'm a little slow with this turbo stuff. I'd like to run an external wastegate with a boost controller as I'm told this can really help with lag. Even though it's a bigger turbo, will it still lag badly to reach lower boost levels?

If your going to drop thousands of dollars on building a motor from the ground up why would you consider a shitty mani?
I don't know a lot about T3 T4s or most other turbos but I do know a T25 will push 15 PSI to redline on a 2.0 DSM. That means it should easilly be able to do it on your 1.6. If the T3 T4 is much bigger then yes you will have a lot more lag. You will also have a turbo with a lot more potential. Maybe the T3 could run 20 or 30 PSI effectively but unless you are aiming for that it won't do you much good.
An external wastegate isn't going to do anything for lag, neither will a boost controller. The external wastegate is mainly to prevent boostcreep but they are loud and IMO annoying as hell. A good internal wasegate should work just as well. The boost controller will give you controll of the amout of boost you will run but that's about it.
The best things you can do for lag is make sure the exhaust path to the turbo is not restrictive and use the smallest possible turbo that reaches your max goal for boost. Of course it also depends on the quality of the turbo and the intake to exhaust turbine ratio and other small things.
It also has a lot to do with your plans for the car. If you want to drag race it then a slightly larger turbo might give you a little better effeciency on the long pull despite the long lag. I on the other hand can't stand lag so I would be more likely to sacrifice a little loss from 6500 to 7500 in trade for instant boost.

Who told you the wastegate and boost controller would help with lag? Did they work at Auto Zone?

[AceX]

If the flange for the turbo was in the center of the manifold, it would help alot. This style of manifold is fine for a turbo setup.

A T3/T4 turbo is a big turbo for the 4age to handle. Even in its smallest trim, the turbo is huge when compared to the T25. If you are dead set on a T3/T4 turbo seteup, I would get the absolute smallest trim possible and run a straight exhaust almost.

I say, unlees you are building a car for the quarter mile drags, or for long trips, stick with a smaller turbo than the T3/T4.

[Luni]

I agree with AceX about the T3/T4. It will max your fuel system fast, it will be slower to spool, you will lose response, and it will feel alot less linear than youre used to.

Yoshimitsu - actually a boost controller can help your lag. Depending on the controller (ballspring, and EBCs typically) it helps spool by holding the wastegate shut until the preset boost is achieved, then it allows it to open. That increases your response and decreases spool time. I do agree that I wouldnt spend money to rebuild an engine for a turbo setup and not spring for a better exhaust manifold.