Dude what.

All intercoolers create a pressure drop. Not "crappy low flowing" ones.

Okay so what happens when you're stepping on it at 30% throttle and 5k rpm and the turbo has spooled up however the wastegate is reading somewhat vac/low psi and is fully closed?

If you want to avoid the "poor flowing ic" connect the source right between the IC and the TB, not in the intake manifold.

first, fix your wastegate can. It is a problem and will continue to be a problem, regardless of how the rest of your drivetrain is setup. Make it straight.

Second, yes, your 3" exhaust can affect boost, *BUT*, it will only be due to boost creep, and if that was the problem, you'll probably only ever see creep beyond 5k+ rpms anyways. The only good solution to boost creep is to have your wastegate ported professionally. I tried having a wastegate ported by a machinist, he did a good job with what he did, but he didn't have a thorough understanding of what needed to be done, the problem was only marginally better afterwards, but still nowhere near fixed.

Third, wastegate signal needs to be sourced somewhere before the throttle body. It's not a BPV. Sourcing your wastegate after the TB is going to turn your throttle into an on/off switch instead of a smooth controllable throttle.

got it. I will fix the wastegate and get a signal before the throttle.
Thanks for the help everyone.

Well give it a try and then celebrate.

1. Okay, I know the function of the wastegate, but I dont understand how to control it. Does shortening or lengthening the rod increase and decrease the boost (PSI)? Or, does it just help with spool?
The wastegate I have, the cracking pressure around 10 PSI. Is there anyway I can get this wastegate to run at 7-8 PSI?

2. Lets say my wastegate is rated at 7 PSI from the factory, is there anything I can use/change to make the wastegate run any lower PSI, or would 7 PSI be the lowest PSI I can run at.

3. Can I shorten my rod by adjusting it all the way to the limit? And, would I shorten rod all the way and then mount it or should I mount the wastegate first and then adjust the rod?

4. Can a MBC be used to lower the PSI below what the wastegate is rated at?

Sorry if I don't make any sense.

Would buying this item below and running it with a MBC solve all my problems?
http://cgi.ebay.com/ebaymotors/T25-T...#ht_1910wt_793

https://www.miataturbo.net/attachmen...ine=1313238971
https://www.miataturbo.net/attachmen...ine=1313238971

What I have seen people do is cut the rod, thread it, and have an adjusting nut for longer or shorter settings.


https://www.miataturbo.net/attachmen...ine=1313244419

Picture is from this thread, diy adjustable wg

If you want more boost put some washers where the wastergate is bolted on, between the compressor and wg plate.

@Hustler , I have no idea what that is

@mazpr , Will shorter settings allow me to run at a lower boost (7PSI) if the wastegate is originally rated 10PSI from the factory? Should I use more preload?

Short rod, wastegate opens later. Long rod, wastegate opens quicker.

I doubt you will be able to get it below 7psi. I have my 7psi IWG rod set max length so I see 3-4 psi at 6k, which is all my shitty injectors can handle because I'm poor. There is no "spool".

God, I am so confused. When people use the term "short rod", does that mean to adjust the length shorter and then mount it,
or
does it mean mount the wastegate, adjust length of rod (now the hole of the rod won't reach the shaft that opens the wastegate), and then apply preload?

Changing the rod length changes the "pre-load" tension for the inital opening of the flapper and adjusts how far it opens. "Shorter" means it takes more exhaust pressure to open the flapper and makes more total boost depending upon the angle of the rod and how far you need to rotate the flapper. The lower the boost the further the flapper needs to open. Make it longer to run less pressure and to open sooner.
Make the rod longer.
You tell me.
Bolt the can then pull the rod to the eyelet on the flapper mechanism.
No.

Thanks Hustler

How do I make the rod longer? Do I mount the wastegate first and then adjust the length? But in this case, the rod won't fit on the eyelet on the flapper mechanism?

Or, should i just elongate the rod as far as possible, and then mount the wastegate?

If the wastegate I have cracks at 10 PSI, is there any way I can check that the wastegate will be at 7psi when i elongate the rod?

You unscrew the threaded coupler to adjust the length. This is all going to be trial and error at this point.

but if i adjust the threaded coupler, which will increase the length of rod, the hole on the rod won't fit on the eyelet on the flapper mechanism.
I know then if shortening the rod, I can apply preload, but if I lengthen the rod, how do I make it work?

There should be a lot of preload already. By loosening it there should be less preload.


Basically if you run it once without connecting the rod to the arm, your waste gate will be fully open the entire time, in other words you will have lots of lag and very little boost. Take it to redline and keep your eye on the gauge especially at higher rpms. If you overshoot the desired PSI by doing this experiment there is no hope of you ever getting your desired low boost out of the turbo u're running just by toying with that arm. On the other hand if you do hit lower than your desired psi, keep loosening the arm and eventually you'll get it although your low rpm psi might suffer.

So if I am understanding correctly, increasing the length of the rod will lower the pressure of the wastegate, but at the same time, it will increase lag.
Would it be better to get a more stiff wastegate, lower than 7-8 PSI (what i want) cracking pressure, and use a MBC to raise my boost to 7-8 PSI?
This way, I can have better spool at lower rpms and maintain 7-8 PSI.

I was looking at this wastegate
http://cgi.ebay.com/ebaymotors/T25-T...#ht_1910wt_793

Yes new wastegate would be the best solution

I read somewhere about a rule of thumb, such that if I wanted to run at a certain PSI (say 8), I should always get a wastegate that has a cracking pressure half of the desired PSI (4 in this case).
Can anyone confirm that this is true