External Wastegate Questions

I am looking into purchasing a manifold mounted wastegate, like the one shown here:

http://www.extremepsi.com/store/customer/product.php?productid=16320&cat=446&page=1

I have a few questions:

1. Is it possible to drill and weld the flange on the exhaust manifold with out removing it from the vehicle?

2. Is there risk to the turbo/engine from drilling the manifold on the vehicle?

3. Would I have to do anything special to my EVO III? I am guessing that by having the wastegate mounted before the turbo, that there would be no reason to alter/close the internal gate on the EVO III?

4. What pressure spring would I want to get? IIRC, the spring pressure corresponds to the minimum boost pressure you can run, which also limits the highest boost you can run.

5. What size wastegate? 35mm, 38mm, 40mm, etc.

6. On the page posted above, what flange(s) would I need to purchase?

7. Where does the discharge outlet go? Do I have to pipe that back into the O2 sensor housing? If I don't and run a dump, how loud is that going to be?


Thanks!

I am looking into purchasing a manifold mounted wastegate, like the one shown here:

http://www.extremepsi.com/store/customer/product.php?productid=16320&cat=446&page=1

I have a few questions:

1. Is it possible to drill and weld the flange on the exhaust manafold with out removing it from the vehicle?

2. Is there risk to the turbo/engine from drilling the manafold on the vehicle?

3. Would I have to do anything special to my EVO III? I am guessing that by having the wastegate mounted before the turbo, that there would be no reason to alter/close the internal gate on the EVO III?

4. What pressure spring would I want to get? IIRC, the spring pressure corresponds to the minimum boost pressure you can run, which also limits the highest boost you can run.

5. What size wastegate? 35mm, 38mm, 40mm, etc.

6. On the page posted above, what flange(s) would I need to purchase?

7. Where does the discharge outlet go? Do I have to pipe that back into the O2 sensor housing? If I don't and run a dump, how loud is that going to be?


Thanks!



well let me first ask why would you want one w/ an evo III usually people only go w/ an external waste gate if they are suffering from boost creep....or have a bigger turbo.... and your dyno report 240? seems way to low for what you have done.... but to awnser your questions

1. it is possible but it would be way easyer to take it off and do it..or buy one thats proffesionally done...

2. yes there would be medal shavings could fall in the manifold and go into your turbo

3. as for the old waste gate yes you would half to remove it and weld your flapper shut...there wouldnt really be any point to having 2 waste gates..

4. not to sure on the spring sizes..

5. 35 would be fine for an evo III

hope it helps
Jesse

well let me first ask why would you want one w/ an evo III

Down the road I am looking to step up the turbo size and every time I'm looking at a larger turbo I seem to find out it needs an external wastegate. I am also partially asking for my own edification.



and your dyno report 240? seems way to low for what you have done



Stock cat back, stock UICP, 17psi.....need I say more. :p

sell yours buy this!

http://www.slowboyracing.com/more.php?id=1891&;

I refuse to do business with slowboy, so that won't work. Also, I can't see spending $300 for the manifold if I can just buy a wastegate and flange and do the installation myself.

Welding steel on to cast iron is risky business, and requries more work. Most places will heat the cast until it just glows, then weld on the steel. Over time the different expansion rates of the two materials will cause cracks. On a race car it may not matter, but on a street car that sees a lot of heat cycling it can add up fast. The other issue with welding a WG on the front of the number one runner is clearance to the radiator. 1Gs tend to be alright, but on a 2G it's tough. This setup on a friends car puts the gate 1mm from the radiator. Even with solid motor mounts it still makes me nervous ;)

The SBR cast piece is superior to a welded on gate in every way. Clearance at the radiator is better, clearance at the water pipe for larger turbos is better. Etc. If I was doing a setup like this I wouldn't hesitate to buy it. If you don't like doing business with SBR, you can go through one of thier authorized resellers. ;)

There is no way in hell I would ever attempt to drill the manifold on the car. With the amount of work and skill required to weld that flange on to cast iron, I Would think removing the manifold would be very simple and quick in comparison. As stated above, not worth the risk of getting metal shavings into everything. Actually, it's not a "risk" if you know it's going to happen I guess... :)

38mm is the largest anyone should need for a manifold mounted gate. Mounted on O2 housings they can be a little small since the path to the gate isnt very free flowing.

The spring should be low enough that you can turn down the boost for pump gas use, but high enough that on race gas you would never be going over double the spring rate. For a 16g sized setup the stock .9 or 1 bar spring will do (~14/15 to ~30 psi range). With a stout setup you can go higher. On the 2g I ran 25 psi daily, so I chose a 20 psi spring. The only time I ever ran 20 was breaking in new motors. Depends on how long you plan to run the 16g, and how big your planned upgrade is. Springs are available seperately for about 25 bucks, so its not super critical that you get it right the first time.

If you don't want to limit the number of future buyers for your EVO3 by welding the flapper shut you can just leave the WG actuator not connected to a boost source, so the internal doesnt try to open. But, the internal will still open on its own at high boost just the same as it would without an external installed. In most cases it probably is ok to keep it that way just as a safety feature. ;) You should still be able to get over 40 lbs/min with it, and it will regulate exhaust manifold pressure.

I always dump the WG to just below the oil pan. For the getto POS method (see the site) you can use flexible exhaust tubing available at autoparts stores. Weld a short tube on to the outlet flange to clamp the flexible stuff on to. It's loud, but that's to be expected, and only at WOT/full boost.