External wastegate on Hks 1.8 manifold
 

Hello,
I am going to install a tial 38mm on my hks manifold.
As you can see from the photo the side that I am going to mount doesn't allow the wastegate to fit ideally.

Attachment 202007

So I came up with 2 solutions.

1. Drilling a smaller hole than 38mm (could this work or am I going to have boost controlling related problems?)

2. Make a flange like in the newb drawing below

Attachment 202008

Any other ideas or solutions are welcome!

IIRC the HKS is a top mount which already puts the turbo up pretty high with minimal hood clearance- won't any kind of spacer cause problems? If those attributes are true, then you'd be better off putting the port opposite the flange opening (where the runners converge) using a short tube. The top mount should allow room for this position since that makes more space under the manifold.

My only concern with this is the welding on the cast iron. Many welders here are trying to avoid it for some reason.

Cant you just have a steel pipe of 2" maybe 5" or 6" long welded to the manifold and push it down to the bottom of the engine or to the front depending on how the turbo pipes run.

I would not go with such a modification to the manifold.

:idea: Your SOL..... get a better mani with a EWG bung already designed in it..... Best solution bar none..... less headache and probably less problems just my :2cents: onther than that you could buy the cheap ebay spacer with one already in it...

http://cgi.ebay.com/ebaymotors/TURBO...Q5fAccessories
or
http://cgi.ebay.com/ebaymotors/t3-tu...#ht_500wt_1182

except one is 400 bux and the other a t3

They're just examples.. :jerkit: not actually solutions to his problems just ideas that he could look into that's all.

I get it.

There's also the issue with hood clearance with a big ass spacer like that.

yea good point..... (refer to previous statement about mani) :giggle:

Nothing wrong with welding cast iron as long as you do it right. Reason people here avoid it is because the mild/ss flows better and mild flanges are readily available. It CAN be done.

Over the last 4-years of track action, I've seen numerous cast manifolds fail, especially cast iron with welding. Maybe its a failure in execution, but not something i would jack with if you EVER want to see the track. I wouldn't trust it on the street either, but if it fails on the street you're not out any track time/$$$.

I have the same HKS mani, and hood clearance is a huge issue. You can't really go up any higher, and the way the manifold is designed, there really isn't any place to put an external wastegate. It's pretty much new manifold if you don't want to run internal.

On that note, my HKS 1.8 manifold has been awesome.

To properly weld cast iron you have to preheat 300* F weld and ping the weld in between passes. While finishing up with post heat treatment. To be honest its not worth the hassel. Thats why its fun to pick up some steel and build something bullet proof. No preheating bullshit just turn on the heat and go.

THIS

/thread

Thanks for the response.
I started to think about it when I saw this, and thought... what the hell, I can be there too.

http://img442.imageshack.us/img442/2274/hksexternal.jpg http://img442.imageshack.us/img442/h...jpg/1/w480.png

Drilling a smaller hole on the side would be a problem ?

I wonder how long it will last until there's a crack between the wg and turbine ports... not long I bet.

+1 It will probably crack between the turbo and the wastegate.

If you decide to stick with cast iron manifolds, there is more room to drill a hole on the Flyin Miata manifold and the iron is thicker and stronger. It moves your turbo to a side mount instead of a top mount. Right there on top is a good location for the wastegate.
http://www.flyinmiata.com/Store/images/22-21000.jpg
Flyin' Miata : Turbochargers : Parts and upgrades : 1994-05 FM turbo manifold


But I would recommend that you buy a good fabricated steel manifold that is designed for an external wastegate. It will flow better and make much more power. And it is beautiful.
This is ABSURDflow:
http://www.absurdflow.com/miata/stdvband/stdvband5.jpg

http://www.absurdflow.com/miata/stdvband/stdvband4.jpg
http://www.absurdflow.com/miata/stdv...bsurdflow5.jpg

ABSURDflow - Available Products

Really? My FM3 has a similar setup and it's going strong. Plus it's i'm like the 4th or 5th person to have this manifold so it has probably somewhere north 200K of miles on it.

Durability all depends on thickness of the cast iron at that section and also the composition of the cast iron upon casting... Choose wisely.

I think there's a big difference between cutting the hole in an existing casting and having the port engineered into the casting. Given the small amount of metal dividing the two ports, it will have to sustain a lot of stress from heat and load.

I'd be tempted to find a spare turbine housing and try to mod that for an external wg port. Or find one made for the purpose.
http://www.atpturbo.com/mm5/graphics...-043_450-2.jpg

Found a modified turbine housing, albeit it's from the Gurney Toyota Eagle MKIII. It can work. These engines made 700hp from 2.1L with lots of boost running for hours and hours on end without failing.
http://octanereport.com/uploads/imag...porsche_15.jpg