rorik

Basically I'm wondering what size wastegate will be adequate. I plan on using one waste gate and keeping the 2 runners internally divided all the way to the gate, just like in the pic, to save cost/complexity, and preserve the twinscroll aspect.
Question is, what size will be adequate? I have a couple 44mm flanges, but haven't actually bought a wastegate yet. The turbo is a holset hx40 with the 16cm housing. (thnx swappedturboegg) If you guys aren't familiar with the holset, substitute it for a gt35r twinscroll, what would work with that? The pic below is of a full race setup, I figured if they do it with the 44mm wastegate, that size might be okay, but I don't really know. I haven't seen that on a honda setup. Basically each side of the collector would only be seeing something like a 28mm wastegate, when you account for the thickness of the divider. That might be okay for holding like 28lbs, but how would I be able to tune without the ability to hold it a lot lower..? Thanks for any experienced input on this..



Modified by rorik at 9:19 PM 1/16/2008

HiProfile

Since a divided manifold gives each pair half the volume, the pulse is a little stronger when it hits the WG, as well as when it hits the turbine. The 'reversion' back into the other side will be negligable, so don't worry about that. In other words, the gate size shouldn't be much different from a non-divided setup, just base it off of boost: lower boost = larger gate, higher boost = not as large a gate. You also have to look at how the pipes come off the manifold. If they're the same size as the runners themselves, chances are it will remove the gasses efficiently.

In other words, the same rules apply. Usually Hondas with divided GT40's run big twin WG's, but mainly because they need to control the impossible - very low boost in the lower gears with a setup that gains 50whp if it creeps 1psi.

ls1_datsun

It works fine if done right..2 wastegates is alot easier though. Also make sure your divider is plenty thick, its not pretty when its not

rorik

So you guys think the single 44 will be adequate?

riceball777

i would just run 2 wastegates to be on the safe side
and if money is a issue just run 2 38mm waste gates

turbodano

The lower your back pressure the less wastegate you need. If your back pressure never crosses 1-1 then you dont need much of a wastegate at all.


What engine is this going on? Sorry if I missed it in your post. The HX 40 is a good turbo for some applications.

SpoolnG2

ususally people use the 44s due to the v-band clamp b/c you can move the wastegate to where you need it positioned which makes it easier to run your dumptubes.

Justin Olson

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbodano &raquo;</TD></TR><TR><TD CLASS="quote">The lower your back pressure the less wastegate you need. If your back pressure never crosses 1-1 then you dont need much of a wastegate at all.


What engine is this going on? Sorry if I missed it in your post. The HX 40 is a good turbo for some applications.

</TD></TR></TABLE>

From what I've seen, the lower the back pressure pre turbo, the more wastegate you need to keep boost down. With little pressure differential across the waste gate, exhaust gas doesn't want to flow through the gate.

Maybe I'm confused on your statement.

Regards,
Justin

rorik

It's a stock sleeve gsr.
I just want an idea of how low the 44 will be able hold the boost. I don't want to run dual wastegates, I'd rather just get a single bigger one.

I'm reasonably sure it will be able to control the boost level I want, which will be in the high 20s on e85, but the thing I'm wondering about is how to tune it without being able to hold it low, esp considering that this will be my first experience with tuning. Either way, if it doesn't work, I'll just cut it off and put a larger flange on. The tubing will merge at an angle, so it should be pretty easy to get the right size at the flange.


Modified by rorik at 3:11 AM 1/17/2008

SpoolnG2

I thought you had to use 2 wastegates b/c it actually like have 2 seperate manifolds come into one. The wastegates are placed right before where the flange for the turbo is. So one wastegate really couldnt control both sides if done properly.

rorik

Uhh..look at the above pic. See the divider? The only time the 2 sides are connected is when the wastegate opens.

SpoolnG2

What manifold is that for? I only see two pipes coming out to the turbo. Where are the rest?

Here is what i'm talking about and used to seeing. Thats where my explanation came from above.

http://www.full-race.com/catal...6f817

rorik

It's a t3 twinscroll up pipe for a wrx, flanged for a 44mm gate.

SpoolnG2

oh ok...haha. Now it all makes sense. A single 44 should be more then fine then.

rorik

and..here it is. Hopefully it works.