Noob Turbo Question - XR4Ti

So, fellow GRMers, despite owning lots of project cars and many turbochargers over the years, I have never put two and two together and had a running turbocharged car.

I'm finally (hopefully) going to get the Merkur XR4Ti going again. (The car was purchased as a joint venture with two friends as a lemons-mobile, but it's been sitting for years). Anyway, as I worked on bolting together the turbo system this afternoon I realized I was missing some pieces of the wastegate actuator (mostly the part the connects the vacuum dashpot and the flapper arm on the wastegate) and that said pieces were going to be a PITA to install even if I found the parts. So, my question is this: do I really even need a wastegate on this car? I don't plan to make any modifications for a while and I hear the OEM turbo is only good for ~18 psi of boost (the OEM wastegate supposedly opens at ~15 psi).

If I don't run a wastegate and just fasten the wastegate flapper closed, am I going to have trouble?

Way I see it, there are two potentially bad things that could happen with this setup:
More Bad - The fuel system can't supply enough gas to cover the 18 psi I'd get with no wastegate and the engine asplodes.
Less Bad - The turbine can't really flow enough exhaust gas to keep the engine breathing at high rpm/boost and I'm essentially going to choke the flow at those conditions by not having the wastegate open up (and thus make a little less power).

For the purposes of testing everything out, I'm not opposed to firing it up without the wastegate, but if I need it, I'd like to get it taken care of at this stage.

Obviously, this is an internal wastegate in case anyone was still wondering.

Also, if you want to respond and say "well you should just run a wastegate because that's the proper thing to do", well OK, but tell me what's going to happen if I don't.

Thanks!

http://www.turbobygarrett.com/turbobygarrett/compressor_surge

I know my 20psi gauge pegged and tried to bend the needle when I installed a boost controller and didn't adjust it correctly on my stock T3 equipped XR4Ti. It blew the headgasket in a surprisingly dramatic fashion. Coolant blasting through the gap between the hood and fender and a sudden loss of visibility due to the steam was an eye opener.

Expect destruction if you run without a wastegate.

In reply to pres589:

That link is in regards to a blow off valve, not a wastegate, correct?

In reply to ditchdigger:

Well that sounds like a pretty good argument against running with no wastegate. It's great when someone can give a first-hand account of exactly what you're wondering about - thanks!

JohnyHachi6 wrote: If I don't run a wastegate and just fasten the wastegate flapper closed, am I going to have trouble?

Yes.

You'll be changing headgaskets at the very least.

Detonation is a bitch.

More likely to break pistons than to get through multiple headgaskets without breaking a piston.

My Ford Turbo experience is with the TBird version which used the IHI Turbo. On that engine you could disable the waste gate and see only 18 lbs boost max but it came on quicker and built boost faster then the XR4Ti T3 version.

I'm pretty sure Les (fastasleep) has some experience running a turbo system with a welded waste gate.

In reply to jimbbski:

That sounds much more in line with what I've read on some of the XR4Ti websites.

Not sure I want to test it out though based on what ditchdigger said.

Weld it shut and run an external gate? You'd still be removing quite a bit, however.

ditchdigger wrote: I know my 20psi gauge pegged and tried to bend the needle when I installed a boost controller and didn't adjust it correctly on my stock T3 equipped XR4Ti. It blew the headgasket in a surprisingly dramatic fashion. Coolant blasting through the gap between the hood and fender and a sudden loss of visibility due to the steam was an eye opener. Expect destruction if you run without a wastegate.

This sounds about right. I ran my Saab 9000 with the wastegate disconnected for about ten minutes to diagnose another issue. The detonation was unlike anything I've ever heard when the revs came up I put the pedal down.

Now, let's apply that to XR4tis, which have a very weak head casting, some cooling issues, and maybe a poor manifold design depending on year.

Good luck!