Wastegate Size

Shift518 Automotive
1

I’m searching for an external wastegate for my RB25 with the Holset HX35 on it. I’m leaning on choosing a Tial 38mm Vband wastegate, but will 38mm be large enough? Will I run into boost control problems if I don’t recirculate the wastegate back into the exhaust?

Thanks dude bros

2

how much boost do you plan on running? on low boost like 8-9psi or so it may/may not creep. just spend the extra 100$ and get the 44.

3

Go 44mm for sure. Or ask Wayne, he’s an expert with WG’s now.

4

a w/g is pretty simple actually…

5

The theory is that a larger wastegate (44 mm) should be utilized on turbos using low boost vs. turbos that are running high boost which should run a smaller wastegate (38 mm). Where did this theory come from? Remember…a wastegate limits boost. If you want to run more boost, you don’t have to limit it as much. Running less boost means you have to limit it more.

6

WGs are very simple, even on the inside!! W/e you get, don’t listen to bryan and buy the wrong spring. LOL

7

is your manifold a twin scroll or single? if its a twin scroll you will need 2 wastegates, or if there is a way of merging the groups into 1 single gate, like the 2JZ hks/greddy headers do.

if thats the case, 2 TiAL MVS 38s would work fine. but if you can get away with a single wastegate a single V44 would work fine. just choose spring rate accordingly for the target boost range. .8bar = 10psi opening, and so on.

8

I’ll be running 10psi for now, so I’ll just get a .8 bar spring. In the future I’ll push it up to 18+ psi via boost controller.

I’ll be modifying my log manifold.

9

Hey now 40 psi FTW… :shifty

10

:rofl

11

:rofl

12

Wayne, don’t make me drive up there with a 2JZ no turbs.

13

Copy/paste straight from NASIOC. Nice.

14

Ok so anyway, how do I know what size I need, I don’t want to spend the extra $100+ if I don’t need it. Or does anyone have a used one? Has to be vband though.

15

ouch caught red handed.

16

Diesel guys run these turbos up around 30psi IIRC, I won’t be pushing more than 20psi unless I build my motor. It has an internal wastegate, but unless I bore the opening larger it will just Byran Baykerin on me. But I’d just rather go external.

17

Internal WG FTL.

18

And I would like to state for the record you cannot rely on HKS charts for certain boost levels.

19

i dunno bout driving up here with no turbz, but if i see that car again it’s leaving without turbz!!! LOL

bahahahahaha +rep if i can.

20

cosigned.