Help me understand wastegates...

[Turbo1gTsi]

I recently stumbled across about $800 that I'm now not going to need for it's original purpose and need some help making a smart purchase. I'm always hearing people talk about the advantages of an external wastegate and was wondering if you guys could help explain the benefit's of purchasing a kit like this...

Lancer EVO ported exhaust manifold with Tial 40mm wastegate and dump tube $815
Picture of kit here....

What would be an advantage of doing this? Also, anyone else have suggestions for a better idea ?? Thanks guys...

 

[L2RTSiAWD]

Well nowadays people are in the O2-mounted wastegate craze. Basically an external eliminates boost creep and flows more exhaust gas than a normal 34mm internal gate.

 

[UltraImports]

that deal doesn't look too bad to me.

(from the amazing turbo link)"The wastegate is just a valve that opens when we have exceeded our desired boost level, and allows exhaust to flow around the turbine, instead of through it. This lowers the pressure differential across the turbine, less work is done, and the turbo slows down.

The only "gotcha" with the wastegate is that it must be able to flow enough gas to let the turbo slow down. If it can't, the you get "boost creep" where boost levels slowly grow as the car remains under boost. Bad. "

So, in order to prevent creep, you have to move more exhaust gases. This is what aftermarket wastegates do for you, help you move more out.

 

[ChicagoGSX]

Or you can raise the boost so that the wastegate has to bypass less exhaust gas.

 

[Turbo1gTsi]

So, in my scenario... This set up would not work for me since I am still using the stock 14b turbo, which has an internal gate, correct? I would have to upgrade turbo's at the same time as buying this set up?

Thanks...

 

[RocketBoy]

With a 14b, your money would best be invested in other places. The 14B's do not flow enough to necessitate the use of an external gate. If you plan on upgrading the turbo, you may want to look into purchasing a logger, larger injectors, and an EGT first. That way, when you're ready for the bigger turbo, you'll already have the basics of what you need.

 

[Turbo1gTsi]

What exactly do you mean when you say...

The 14B's do not flow enough to necessitate the use of an external gate.

I thought if one experiences boost creep then the boost was "flowing too much for the wastegate to handle" wouldn't that mean it flows "enough" ?? Just curious, and a little confused now...

 

[Turbo1gTsi]

What exactly do you mean when you say...

The 14B's do not flow enough to necessitate the use of an external gate.

I thought if one experiences boost creep then the boost was "flowing too much for the wastegate to handle" wouldn't that mean it flows "enough" ?? Just curious, and a little confused now...

 

[DrZiplok]

In simple terms, the larger your turbo, the larger the wastegate you need to effectively control it, all other things being equal.

In your case, the 14B wastegate is mostly up to the task; if you are having creep problems you should be able to solve them with a bit of porting on your wastegate.

I note that you don't seem to have any fuel control, and probably little or no headroom left on the stock injectors. I'd have to go with the folks that are suggesting you look at your fuel system with your extra cash.

 

[Turbo1gTsi]

I'm definitely going to, right now I just have a Walbro 255 and an Apexi S-AFC for fuel mods. I'm waiting on a good price on some 750cc injectors...

 

[DrZiplok]

I'd be inclined to suggest that 750s are complete overkill for your application.

One of the drawbacks you face with larger injectors is that getting them open for a short period of time is pretty hard, so making them idle well can be something of a challenge.

What, exactly, are you doing or planning to do that requires injectors that size? With your current setup or even a moderate upgrade you should be more than fine with 550s, which can be had quite cheaply.

Remember; buy what you need, not what has the biggest number printed on the box.

 

[Turbo1gTsi]

I was going to go with the 750cc injectors because everyone I've talked to, said to make sure that you only have to upgrade 1 time for cost's sake. I bought that damn S-AFC for a reason, and I've read it can handle (or lean out) these injectors enough to run them in my application, however the main reason for the 750's is that soon I'm purchasing a 20G, and wanted to make sure I didn't have to run out and buy new injectors again after that's on the car... Wouldn't you say that buying the 750's are smart if your going to need them eventually?
Thanks....

 

[~laser_craver~]

One Word COMPLICATED

 

[Turbo1gTsi]

Tell me about it man....

 

[Bohrn]

750s are bloody HUGE!

you need a built motor and tons of supporting mods for them.

510s or 550s will make lots of power. Even 650s are over kill. Hell even the stock 450s are good for a little over 300 hp.

And as for the turbo thing, a good 16g that is properly ported and has a larger wastegate door installed will not creep either. Slowboy and some others do this.

No you wont have the bling bling pipes and huge injectors but you will go fast. And idle, pass emissions testing, get good mileage, and be able to drive it to work everyday, and not have to keep it running or be embarrased by the crappy idle.

 

[Turbo1gTsi]

I wish there was a better way to tune other than using this damn S-AFC... I hate trying to use that thing.... hopefully it will be easier when my datalogger gets here. What size of those injectors would you suggest for me then?

 

[Bohrn]

depends on many things.

Seriously, use the tuning guide. It works.

not trying to be an arsehole either, its just the truth.

 

[Turbo1gTsi]

Yea, but there's so many diff tuning guides to follow with different information everywhere you turn... which one are you referring to? Thanks...

 

[Bohrn]

the one on the main page, that says "Tuning Guide" http://www.dsmtuners.com/tuning-guide/

then ya just have to follow the buttons for your car.

eg, 1g, turbo. Or 2g n/a

then go for the stage1 stuff for power, and handling.

also do all the stuff for maintainance in www.vfaq.com

apparently there is one at Roadrace engineering, and Dave Buschers place too.

 

[Turbo1gTsi]

Ya, I've been trying to follow the Buschur Racing site's... I really like them, I've ordered soo much through them in the past, they seem to really know what they're talking about. I just wish there was a better write-up on help adjusting the fuel settings on my S-AFC. That's what I was really talking about in my last post... I've read a ton of them, and so far the RRE one has been the most helpful, but really I still need help with it. Maybe it will be easier to adjust when I get larger injectors and a datalogger... Do you use a datalogger or an S-AFC in your setup?

 

[Bohrn]

I don't have a logger or S-afc yet. I know I need a logger and maybe an exhaust gas temp guage as well to continue my tuning. Right now I am just going on what others have done before. Pretty conservative, but it is still a pretty fast car

Next mod will probably be a 190l/hr fuel pump, as I hit fuel cut at about 6300rpm, and that means I'm runnin lean up there. NO good.

I don't think I will get an S-AFC until I need bigger injectors, as the 450's are gonna be good for a bit more. I don't plan on cams, bigger turbo, injectors or computer for a while.

If you have a stock turbo and injectors, you should set it for baseline for now and let your factory computer do its job. I believe you only need to use the AFC to help you make bigger injectors run properly, and tune the fuel curve. While you could do that with the 450s, you should log the runs and have someone help you interpret the results. You could send your logs to someone who knows that stuff and they could tell you what do do with your afc.

best of luck,

 

[JET]

No, that is not right. If you are hitting fuel cut you are over running your MAS. You need to hack your MAS more or go to bigger injectors. If you are running lean up top you are going to put holes in your pistons. Unfortunately our cars are not smart enough to know when they are running lean, except that it will start knocking at it will pull timing then, but that is not fuel cut.

 

[Bohrn]

I gotta get a logger for sure.

But a bigger pump will help won't it?? More fuel? I am only having problems at almost redline, wouldn't a bigger pump stop that?