What size external gate for a GT35R?

[Boosted98gsx]

Planning on going with a full garrett GT35R. I know any gate size "will" work, just will increase minimum boost. What I'm wondering is would I be safe with a 38mm TiAl and be able to run 18/20 psi daily?

 

[prostreetdsmx1]

at 20psi you will be fine with a 38mm gate.

 

[CanadianTSi]

The Spring Inside the Gate Control's minimum boost, not the Gate Size.

 

[prostreetdsmx1]

i think he is most concerned with issues like creep or something like that if the gate wasn't small enough. if you were running lower boost then i would say go larger but a 38mm gate will work properly for you if you set it up right.

 

[CanadianTSi]

A 38mm Gate will hold 6psi all the way to Redline on a SBR GT-13.

 

[Boosted98gsx]

yes I am more concerned with creep so that's why I was wondering if I needed bigger than that. What would you say the minimum boost would be (at redline) using a 38mm gate on a 35r?

 

[zross1]

I've been able to run 15 psi with a tial 38 no creep with a gt35r.

 

[unlmtdndeavor]

why not go bigger...if you look, the fp 30 series turbos (aka gt30r) come with a 44mm. plus the v-band is just so easy

 

[prostreetdsmx1]

not really a reason too. Honda guys tend to need larger gates because they run much lower boost than we do but as a DSMer you are entiltled to run atleast 20psi and at that kind of pressure the 38mm will do more than enough.

 

[Boosted98gsx]

44mm is all gravy, but I'm not planning on getting a tubular manifold made for the setup. I'd rather run a cast manifold and not have to worry about cracking since this is my daily.

 

[Kevin Jewer]

I think it's worth mentioning that it also depends on where the gate is mounted. Venting all 4 runners at the manifold, a 38mm gate is MORE than enough for any boost level you plan to run (My old skool 35mm deltagate held the 13 psi spring pressure to redline with a 35R sized turbo). On the O2 housing however, poeple have found that a 38mm is not always enough to run low boost. Going a little larger in these types of setups is not a bad idea if you have some reason you need to run low boost. At 20 psi though, as stated above, a 38mm in just about any configuration should be enough.

 

[Boosted98gsx]

It's a GT35r.... It will be manifold mounted. It's just either turblownetics or I need to find another cast mani to work with.

 

[PSI NRG]

Why not run a tubular? Alot of companies make good stainless manifolds. I run the DNP its the ones that people buy on ebay or come with lack of supporters and the weight of the turbo or the waste gate cause them to crack. Plus they look way cool!

 

[topstreet]

My old 35R setup was never run at less than 22psi, but the 38mm held it flawlessly at that level.

 

[qtxdevilz]

i have run up to 25 psi on my sc61 bb with a 38mm tial...no problems...

ams sells there gt35r kit with a 38mm gate...

 

[Kevin Jewer]

The concern with the smaller wastegates is not about running high boost, but running low boost.

 

[Eagle 5]

The concern with the smaller wastegates is not about running high boost, but running low boost.

I think a lot of people do not realize or understand that the more boost you run, the smaller the wastegate you need. If you want to run something like 5 psi on a huge turbo like say a GT42R (just an example) you would need a rather large wastegate to route enough exhaust gases around the turbine to keep it from creeping. Where as if you ran say like 50 psi on that same turbo, your wastegate would not need to be anywhere near the size as if you were running the 5 psi since you do not need to route as much exhaust gases around the turbine.

The more boost you run, the smaller the wastegate you need. Now ya the spring in the wastegate comes into play too but a wastegate would only be able to flow so much exhaust gases through once it is opened all the way.

So, all those honda guys running small boost on large turbos need a larger wastegate to route enough of the exhaust around the turbine and keep the turbo from creeping.

 

[Kevin Jewer]

And this is why I could never figure out why wastegates were rated by HP. Bizarre.

 

[CanadianTSi]

I was actually thinking about this today, of course at low boost your going to have alot of exhaust gas flow bypassing the turbo and going through the wastegate.

Now at high boost your not going to have as much air bypassing the turbo, except your flowing much, much more air overall. So wouldn't you still be flowing alot of air out the wastegate as well?

 

[Eagle 5]

I was actually thinking about this today, of course at low boost your going to have alot of exhaust gas flow bypassing the turbo and going through the wastegate.

Now at high boost your not going to have as much air bypassing the turbo, except your flowing much, much more air overall. So wouldn't you still be flowing alot of air out the wastegate as well?

Yes but a lot of it is being used to keep the turbo spooled up.

 

[Kevin Jewer]

To give an extreme example for the sake of illustration, I run my stock EVO8 turbo completely maxed out, no vac line to the WGA. The WG doesn't even open. The higher the boost/airflow you are trying to run the more exhaust gas energy the turbine requires to keep the compressor moving.

 

[GVR4592]

To give an extreme example for the sake of illustration, I run my stock EVO8 turbo completely maxed out, no vac line to the WGA. The WG doesn't even open. The higher the boost/airflow you are trying to run the more exhaust gas energy the turbine requires to keep the compressor moving.

What boost level does it hit with no line?

 

[CanadianTSi]

That Makes sense.

And I would assume it would spike to 30ish and probably fall to 25ish.

 

[Kevin Jewer]

Depends on temperature. I've seen spikes from 24 to 30 psi, and it tapers down to ~19-21 by redline. Looking at airflow/time, it maxes out right at the spike and flatlines for the whole gear. Boost is just a byproduct of this, and ultimately just mimicks airflow/time (VE).

 

[MarsaGSX]

hey,
that really make a sence..so, can you tell me why my Internal gate on my BEP TO4e 50trim spikes when boosting around 20+PSI and if run only on WG spring..10PSI my BOOST is constant...no spikes...I think its 38mm flaper..Iam not sure..
but still..to controling/regulating higher boost(say 20+PSI) need "smaller" gate than regulate 5PSI... Is it that WG shaft??

Iam using SBR MBC..taped like on their drawing..MBC is taped on one vacuum line with BOV..source in manis..look at pics in my gallery..

Venca