Megan racing catback yay or nay

[MidnightTSI]

Hello everyone, I am doing my exhaust because with my new frontmount I got from talontsi, it seems as if my exhaust cannot keep up with the intake side of things. I bought a o2 sensor housing dump that attatches to the megan racing downpipe I just purchased. I already have a 3" setup but it is custom fabbed and kind of ghettto. I am either A; get the dowpipe welded to my existing catback or B; buy the megan racing catback which is also 3" so the whole system goes together better. My existing catback is kind of ghetto and doesn't exactly mount up perfectly. Do you guys think that the megan catback will make much of a difference? Is it worth the extra $400 or should I just stay with my existing catback. I searched on the megan catback but couldn't find much of anything thanks guys. :)

[MidnightTSI]

I also forgot to mention that I am getting boost creep really bad with the new front mount and this is why I'm doing the exhaust. With my boost turned all the way down it will go up to 9 pounds which is where it should be around and then in 3rd and 4th when i'm in higher rpm's for longer it will go up to around 15 pounds and stay there. Me and talontsi (JP) figured it should be the exhaust or a wastegate issue because my o2 sensor housing is also custom fabbed and restrictive. But I will be replacing this shortly.

[v413nc3]

Boost creep isn't specifically a "exhaust problem". If you dump your O2 to atmosphere then you either A) have an inefficient boost control method B) have too much flow over the turbine and not enough flow out the waste gate (not a large enough gate).

The only thing a larger exhaust would do for you is possibly make your boost creep worse. What engine are you running, what turbo, what boost control. These are all things we should know before we can even help you with your problem.

[MidnightTSI]

Oh ok I am running a stock 4g63 2.0 with a big 16G and a hallman pro rx boost controller. I haven't put the new o2 housing and downpipe on yet so i'm not sure if that will fix the problem. I now have a weird looking o2 housing and a 3" downpipe that looks restrictive so that will be replaced soon along with a new megan racing downpipe. I had no problems with the wastegate before the new front mount which flows way better. I am also only running 15 pounds of boost.

[v413nc3]

With a manual boost controller and your setup it would be best to set the boost to what level you wish to run in 3rd or 4th gear. It will vary between 1/2 and 3/4 significantly. If you have your boost set at 15 and it goes to 15 I fail to see how it is creeping.

[MidnightTSI]

It is turned all the way down to 9 psi. It gets to nine psi in first and almost all the way through second. At the end of second it will go to about 13 or 14 psi, then in third it will go up to 15 psi and stay there. It will be 15 in 4th and also in 5th. Before I had the new frontmount I had it set at 15 psi. Once I put the new frontmount it was creeping up to 18 and sometimes 20 psi but I would let off. I then got a new hallman boost controller and turned the boost all the way down. What you first read above is what it is doing with these settings.

[v413nc3]

It sounds like your wastegate isn't large enough to control the boost.

[MidnightTSI]

Cool thanks that's what I was thinking. That's weird though because I'm only trying ro run 15 psi. Thanks for the help.

[v413nc3]

For future reference it's yea. Yay is an exclamation, yea is the affermation of a vote.

[MidnightTSI]

Thanks for the info :)

[cotsi95]

Slow Boy Racing sells a 34mm waste gate flapper that you can put in your 16g. I have it in my evo3 but I haven't used it yet. From what I hear that will fix your boost creep.

http://www.slowboyracing.com/more.php?id=108&

[MidnightTSI]

Sounds good guys thanks.

[MidnightTSI]

I just ordered it! ;)

[nefkntym]

I had the same problem back way when I got my B16g. A ported wastegate port and the 34mm flapper will do the trick. Don't over port the passage though.

[buckley]

I must be one of the lucky ones. I always here about how the 16Gs seem to creep like hell but when I had mine, it held 18 lbs perfectly with no creep at all. I guess I'm just a lucky guy aren't I?

buckley

[Mirage]

Slow Boy Racing sells a 34mm waste gate flapper that you can put in your 16g. I have it in my evo3 but I haven't used it yet. From what I hear that will fix your boost creep.

http://www.slowboyracing.com/more.php?id=108&

Be wary of the larger wastegate flappers. Especially on an internal wastegate setup.

True these will help fix the boost creep issue, but it will also cause a boost dropoff at higher boost levels.

The internal wastegate doesn't have enough spring tension to keep it closed with the larger flapper at elevated boost levels and backpressure (>20ish psi).

If I would do it again, I would just port the crap out of the turbine housing and smooth the flowpath to help wastegate port flow. I wouldn't go with the larger door.

Marcus

[MidnightTSI]

So as long as I am running less than 20 psi I should be okay with the larger flapper?

[Mirage]

It'll really depend on your setup and overall airflow through the engine.

I throw the 20 psi number around loosely.

It's typically above 20 psi though by what I've found in my experience.

Marcus.

[MidnightTSI]

Ok well I am only going to run 15 psi until I build a new motor so I will go with the larger flapper for now. Thanks a lot for the help.

[birelshifterkart]

For future reference it's yea. Yay is an exclamation, yea is the affermation of a vote.

And affermation should be spelled AFFIRMATION.

http://en.wikipedia.org/wiki/Affirmation

Isn't there a spell check on here? Jeez. :confused: I'm surprised you of all people don't use it.

[MidnightTSI]

I wish people would focus more on the problem at hand than the grammatical errors of the threads. I know it must be kept professional and that we can't use ebonics but sometimes it seems like more bickering than helping each other out. I guess that's why ^ got banned lol. But to get back on topic thanks for the help on the boost creep problem guys.

[WyoDSMer]

Did the larger flapper fix the creep problem?

[Sparetire]

I dont see the point in running a 16G below 15PSI. A stock fuel system with maybe a rewired Walbro should hanlde 15PSI from a 16G no problem. With a front mount, I think 15PSI is quite a safe and DDable level. And with a good exhaust, I doubt you will get much below 15PSI even with the 34MM flapper. A nice 02 setup should be a big help though. Make sure it has provisions for plenty of flow on the wastegate path. And if possible datalog and see what your 02 voltage/knock situation looks like at a minimum.

I would do as Marcus suggested and port the crap out of the WG passage. Not only will this help with boost creep, it will give the car a bit more top-end power. IMHO the larger flapper is totally useless without port work anyway. In fact, much like a 1MM oversized valve on a stock sized seat, it will likely restrict flow by being a bigger hunk of metal in the path the gas is trying to use. So when you install it, make sure to enlarge the WG hole it goes over to the point that its as big as possible without allowing gas past when the flapper is closed. I think there is a pretty good VFAQ on porting the turbine housing. Its actually quite fun IMO. :D

[MidnightTSI]

Sounds good guys thanks for the help. I haven't installed the flapper yet because I am going to try the new O2 housing and new downpipe setup first. The only problem is that I have a SSAC dumper and everyone is saying that it doesn't quite match up with an aftermarket DP. People on DSM tuners said that the DP will hit the oil pan but I looked at some punishment racing O2 housing dumpers and they look the same as the SSAC one. I actually asked SSAC and they said the dumper only matches up to a stock DP. I need to order another dumper and then see if that will fix the problem, hopefully it does so that I can tune on the 28th! :)