Just purchased kit with MSPNP on the way. Questions. GT2871R. Stock Internals. 1.8
 

Hello everyone. I've decided to step into the boosted world and purchased a used turbo kit(GT2871r w/BEGi manifold and downpipe, RX-7 550cc injectors) for my car. It also came with an AEM wideband and I have a MSPNP on the way. I'm about to start installing the kit but I have a few questions that I need to clear up.

1997 Miata 1.8(stock internals)

-The previous owner stated that the internal actuator puts out 12-13psi. On stock internals I would much rather be boosting at a lower psi. 7-8psi is what I'm thinking. Will I have to purchase a new actuator or can I adjust the arm to put out lesser psi?

-I'm feeling that I need to take it to a dyno in order to get whp numbers for a reliable setup, but I would also like to start slow and tune the setup myself(street tune) in order to gain experience and be more in tuned with my car. I'm currently reading the Megamanual and as much online info as I can. My question is..will I be okay with boosting a GT2871r at 7-8psi on factory 1.8 internals? I'm aware that different turbos flow at different rates and I don't want to exceed 250whp. I don't think that I can achieve that much with the amount of boost I plan on boosting but I would still like to make sure.

Yup

What type of actuator is compatible? Any Garrett actuators or is there a specific type/length?

If the rod of the actuator is threaded, you can adjust it.

if the can is set up for 12psi, loosening it will only make him spool slower and he'd still creep at high load and likely blow his engine.

OP - you need EWG. that kind of turbo on a stock motor with iwg is just asking for trouble.

That's such bad news...sigh. I tore down the car today and prepped it for boost. The manifold has to be modified and so does the turbo for EWG..the downpipe as well I'm assuming. So...I just purchased a kit that I can't really use. Sad. Any other methods? Can I possibly purchase an 8psi actuator and replace it??

why don't you just buy a low-psi wastegate, set agressive overboost protection and see how it handles?

This is what needs to be done. You want to run 7-10 psi or so through that turbo. Anything more then that and you will be in the bending rods territory. With my GT2871 I made about 225hp at 9psi on my built motor.

Is this what you are referring to?
Wastegate Actuator, GT28 Stock Unit- TREADSTONE PERFORMANCE

Also for Overboost Protection I'm looking for set the limit to 152kpa(default). Should be okay there right? This will be mostly daily driven.

I've found I need to set it a psi or two higher than my target boost as it'll hunt around a bit with temperature and the like.

An EWG is the most expensive suggestion and not required at all. A lower psi can is what you need, try calling FM and tell them the turbo you have, I'm sure they have a 7-8psi can that'll work. It might even be on their site.

Believe I've found it!
https://www.flyinmiata.com/index.php...umber=02-70576
But to be sure I'll give them a call today.

Also editing my previous kPa limit to 162..which should come out to about 9psi. :)

Measure the rod. Study the mounting bracket design. Go on ebay. Buy a lower psi Act Chew Waiter that has the correct length rod range adjustment and a compatible bracket design configuration. Some brackets can be removed from the actuators so you might be able to reuse the one on your turbo.

Sorry, but that's downright stupid.
I've ported the iwg port extensively as well as ran a 7psi can before, and with 3" exhaust on a long high load pull it would still creep.

I've experienced this with numerous turbos with very similar results. So have many others over the years. So has FM and BEGi. This isn't something new.

Have you any 1st hand experience with exactly what OP is asking about? If you did, you wouldn't say silly things like this.

Dont be a wuss. Attain greatness. I rant this on a larger turbo with a stock bottom end with a 145k+ miles on it and never blew it. 8psi LOL pppfffffttt

That right there. Loosening the rod will only make the wastegate flapper not close fully so you'll always be losing pressure that should go into the turbo while at redline the wastegate wont open fully until that 12psi mark.

18psi, yes, I have experience running any number between 7 and 10psi with 3" exhaust without issues on an IWG.

I never said they were perfect, and EWG is certainly the better technology, but saying such an expensive option is THE required fix without even mentioning the $60 option is poor form.

I'm saying its THE required fix because it actually is.
Porting and using low pressure can is NOT a fix, it is a band aid, or work around.

Congrats if it worked for you, maybe its the higher elevation or whatever else (perhaps much smaller turbo?) that helped you, but like I said: I and many others (in fact most others) have experienced the exact opposite results.

But if OP wants to try to the low pressure can + porting and it works for him, that's great. I'm all for people achieving good results with less investment. If it doesn't though, he will have wasted time and money for nothing, and will still end up needing a "real" solution.

if porting fixes creep, then porting is a fix.

yeah IF

And IF it doesn't then he wasted money and time.


Whatever, lol, OP can decide for himself.

I probably had some of the worst creep around after I ported my head and fit a 3" exhaust. porting the wastegate *fixed* the creep.

this was my 6psi wastegate:

https://www.miataturbo.net/attachmen...ine=1359387451

I had a GT2871R on my NA, granted the engine wasn't stock but it wasn't an extreme/all-out build either. Anyway the adjustable actuator rod and ported internal wastegate worked just fine to control boost without sacrificing spool and without creep. Also was on a 3" exhaust. Started with it set around 7-8 psi after the engine was first built and then adjusted it to 10 psi after the break-in and some tuning on the Hydra.

You also never loosen the rod to where the flapper won't close. If you can't obtain your minimum boost target without loosening it that much (which is a lot by the way), you need a different length adjustment rod end.

I have a 3" exhaust, IWG, cheap chinese 2870 and no boost creep at 6-8-10psi. Perhaps a fabricated mani might increase the propensity to creep due to higher efficiency, but I'm running a FM log mani. My Greddy Profec B gives me predictable results every time and so does wastegate-only pressure.

I didn't have problems with creep on my stock 1994 motor and gt2871. If you do have trouble I'm sure you could find someone with a 2560 that would be happy to trade, if you don't have aspirations for a built motor you'd probably be better off anyway.

I'm assuming that you ran 7psi?

I'm leaning towards the External Wastegate route..and here's why.

For a new actuator it'll be about $100shipped from here. (Garrett Internal Wastegate Actuator Special 7 PSI GT28R | eBay)

Wouldn't it just be a little more for a Tial Wastegate and flange?
I'm still uncertain as to what I want to do with the internal wastegate valve. Either weld it shut or find another route that isn't permanent.

But yes, if it's not too much then I'm willing to spend extra money for a permanent fix and to also have a more reliable setup.

A typical Tial 38mm wastegate is about $250 new or you can search various classified sections and find a use one for a bit less. Depending on who does the work to your manifold, they can provide the flange (or they're about $20 for a normal bolt type), so figure in the cost of labor for modifying the manifold. Most people weld the flapper shut when moving to an external gate. Then you'd need to rework the downpipe to support an external gate or buy a new one suited for it.

Don't know your budget, but you may consider selling just the manifold and downpipe you have now and buying a manifold and downpipe already made for an external gate from BEGi or FM (FM has the FMIIR system which is externally gated). If you have log manifold now, both BEGi and FM log manifolds put the turbos in the same location, so your intercooler piping will still hook up properly.

I found a new 38mm Tial MV-S wastegate with flanges, v-bands, 9psi spring, etc for $175 local. I'm considering it but not yet familiar with a water-cooled wastegate. I'll have to do more research on that. What do you guys think?
TiAL Sport.com

I do have a little Harbor Freight welder that I can use to weld on the flange and the valve shut. That should save me a few bucks and give me a bit of that DIY feeling. My welding skills isn't great but I have welded an exhaust system together. I'll consider doing that or taking it to a professional welder.

I have the BEGi log style manifold. I looked at it and found a flat spot on top in the middle where I can mount the flange. Hopefully it won't interfere with the hood or other components.

IWG actuators are $40 new on egay.

This is hilarious, For years we've been bashing n00bs for completely half assing things and ghetto rigging their cars, theis guy wants to do something completely the RIGHT WAY and you gays are basically talking him into doing it the cheaper, inferior way that's not guaranteed to work:laugh:

I'm cheap and inferior. It's what I do.

I assume that 90% of the site runs internal wastegates without any issues and you're suddenly acting like it's some timebomb $99 ebay manifold with a powercard running 15:1 at WOT.

The site is all about cheap and function, if he's already got one very workable setup it's more than likely going to be cheaper and easier to lower the boost on the IWG than to convert the whole thing to EWG. If he wants to upgrade that's great, but most people just don't seem to think it's necessary.

Replacing the wasgate actuator is cheaper and easier than welding a EWG flange to a cast iron manifold, reworking to the downpipe to accept the EWG tube, and buying a new EWG. And it IS guaranteed to work.

Sure I like doing things the *right* way, but I also don't like opening up cans of worms; the added EWG could easily end up being the ghetto-rigged solution.

This would be like buying a new set of 949 6ULs in 15x10 with unmoutned Hoosier slicks, that you mount and balance yourself using a prybar and super glue, because you got a flat tire on your DD miata.


Hell, I bet if he calls BEGi, they can hook him up with the lower pressure wastegate, I know FM sells the 8psi one for $60, but I'm unsure it will mount properly due to the difference in setups.