"Big" 16G and 6cm/7cm housing

[16GTSI]

Turbo gods, i'm looking for a little help here. I bought a big 16g turbo from Mach V Motorsports but it didnt include the (7cm) exhaust housing that normally comes on the 16g. They stated that you can use the stock 6cm housing for a faster spool and direct bolt in. I am going to be using it for a daily driver @ 16psi. My question is....Is it really ok to use the 6cm housing? Will there be any problems? Will it greatly hinder the performance of the turbo?
Only reliable responses please. I dont want any "i think" or "in my opinion" posts.

Thanks

 

[Spidey]

Cant comment on how it effects performance, but you can always buy a 7cm gasket and port-match it

 

[Boosted98gsx]

dont do the above. send it back and buy a big16 with a 7cm turbine housing. the 6cm housing is too small for the amount of air the comp wheel flows (big28 killer) and thus making the turbo inefficient. Also, when you/if you get a new big16g get the wastegate flapper upgraded to a 34mm flapper and have the turbine housing ported even more. Trust me you want to do this to maximize the efficiency of the big16g.

 

[16GTSI]

Well considering i have had the turbo for a while does anyone know where i can get the 7cm housing seperatly???

 

[Kevin Jewer]

I ran both housings on the 16g and didnt see much difference at all. Traps didnt change either. But I just felt better using the 7cm housing. Keep in mind though that poeple use 7cm housings all the way up to 50 trims and some 60-1 (red), so it can flow a lot of air. The 16g only flows 6-7 pounds more than a 14b for most poeple.

Another thing is that upgrading to a 34mm flapper may help creep, but it will cuase other problems. The larger the flapper the greater its tendency to blow open at full boost. In my case I was getting up to 38 pounds per minute, boost set to 24 falling to 19. I wired the gate shut, and got 40 pounds per minute, and boost held 24 to redline, sometimes dropping to 23. Most people (including myself) are/were quick to jump to the conclusion that the turbo wasnt keeping up with the well modded car. So the moral of the story is do everything in your power to reduce boost creep without enlarging the flapper. Use that as a last resort.

 

[coppergst]

I have a small 16g with all of the supporting Mods. What can I do to reduce boost creep? It is a real problem for me and I though that going to an oversized flaper was the only solution.

 

[Kevin Jewer]

See the porting vfaq. 95% of creep will be eliminated by proper work in the watstegate exit area. I got my 14b creep down from 22 to 16 right there. Opening up and smoothing the hole got me to 15 psi. Since you have a 2g, in a dition to portmatching your turbine housing work, take the divider back enough to allow the gasses to get around the O2 sensor (which they stuck in the worst possible place on 2Gs). If this doesnt work (I sometimes have to go back in more than once) then use the larger flapper as a last resort, just be prepared for the consequnces if ypou plan to run high boost.

 

[16GTSI]

what were the differences between the two? Was it mainly power or spooling?

 

[Kevin Jewer]

I didnt really see a measurable change is spool. The 16g spools so fast anyway I dont see the point in worrying about the small difference. I "felt" like it had a little more pull at high rpm with the 7cm, but that may have just been because i was expecting it. I didnt see an appreciable gain in traps. I would just feel better knowing that the larger housing was on there, but I dont see using the 6 cm housing as a problem either.

 

[nine5raptor]

A lot of creep can be tuned out as well. For me, simply leaning it out got rid of creep on my 14b (not all 14b's on 2g's creep, though many say they will). The problem seemed to be with the stock setup, secondary combustion was occurring in the 02 housing and causing me to creep to 20+. With a little tuning, it doesn't creep even a single psi.

 

[kpt4321]

You must have ben REALLY rich then, because within the normal realm of tuning, leaner will bring more creep.

.....Kyle T.
93 TSi AWD "TURBO4"
14b - 12.8 @ 108

 

[deusxmachina]

To quote, or at least paraphrase, a (in)famous DSM tuner: "If you have a 6cm housing, you are weak. And you will get whipped by the guy who bought a real turbo."

But it's for a daily driver, so it's not a big deal. Autocross guys have used 6cm's quite a bit. I'd make sure to get some money back on the deal though for having received a "lesser" housing. I didn't know anyone even sold 16g's with a 6cm anymore unless the person specifically asked for it. Unless you meant it didn't come with *any* exhaust housing.

 

[Kevin Jewer]

I dont think I've mentioned this yet, but since 14b has done 11s, so has the 6cm housing

 

[nine5raptor]

Timing goes up, and creep disappears if I lean it out 10% at wot. Anymore and I start knocking.

This is on stock injectors with 14b at 16psi, steveteked, rewired stock pump, maft.

Originally posted by kpt4321
You must have ben REALLY rich then, because within the normal realm of tuning, leaner will bring more creep.

.....Kyle T.
93 TSi AWD "TURBO4"
14b - 12.8 @ 108

 

[16GTSI]

the 16g didnt come with an exhaust housing at all and gsxracer has a good point about the 6cm housing

 

[kpt4321]

Originally posted by deusxmachina
To quote, or at least paraphrase, a (in)famous DSM tuner: "If you have a 6cm housing, you are weak. And you will get whipped by the guy who bought a real turbo."

Sounds like that moron at HRC.

Or JayHass, but he's not a moron.

The sad thing is, there are a lot of 14b / 6cm^2 cars what will "whip" a lot fo 16g / 7 cm^2 cars.

....Kyle T.

 

[deusxmachina]

Sounds more like Marco from Magnus. I'm always happy to listen to advice from anyone who can successfully run a 10:1 compression car at 26+psi -- on pump gas.

Of course a smaller turbo'd car can whip on a poorer-shape bigger turbo'd car, but turbo to turbo, a 6cm is going to choke the top end. Not only do most people run 7cm's, but they run ported 7cm's. For a daily driver on the street, it's not exactly a big deal, though.

 

[Kevin Jewer]

Porting has nothing to do with the size of the housing, just the inlet. Even if you make the inlet larger, it still has to neck down to the same entrance. Most of the benefit is in porting the exhaust manifold outlet and contouring that better IMO, and port matching the turbine housing just becuase you have to match the work in the mani. I personally have never gained anything measureable from porting the turbine inlet on either the 14b or the 6 or 7cm 16g. Even on my "big" turbos I just remove the step on both pieces and drive it on... On my current 20g, the previous owner trapped 123 or so with a completely unported 7cm housing. Thats about the same 99% of people with ported housings run But to each his own... Its still good to do. And why the hell am I still rambling on...