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-   -   Lowering Boost Method (https://www.miataturbo.net/diy-turbo-discussion-14/lowering-boost-method-13006/)

jay526 09-30-2007 07:59 PM

Lowering Boost Method
 
So I've been searching around to see if I can find a way to lower the boost in my T3. I know that lengthening the actuator rod will work but will make it spool slower.

Here is another method I found:

http://www.denverspeed.com/wastegates.html

It looks interesting but the author doesn't give much details. Does this method help reduce the negative effects of lengthening actuator rods? What the benefit of adding this spring?

Thanks guys.

Braineack 09-30-2007 08:01 PM

why would you want less than 7psi?

jay526 09-30-2007 08:11 PM

I am a newbie at this so I want to set it at 5 psi and work my way up. I am purschasing a WB and will be using that to tune. I just want to set the turbo at a "safer" setting, learn to tune it, then increase the boost later on.

Arkmage 09-30-2007 08:21 PM


Originally Posted by jay526 (Post 157983)
I am a newbie at this so I want to set it at 5 psi and work my way up. I am purschasing a WB and will be using that to tune. I just want to set the turbo at a "safer" setting, learn to tune it, then increase the boost later on.

Agreed, I'd prefer to start a bit lower than the 8psi on my can. I've never tuned a boosted car from scratch so there is about a 90% chance I'm going to toast my motor.

cjernigan 09-30-2007 09:07 PM

Depending on what EMS you're using, the megasquirt base maps we have available are pretty damn close for just about any car. Close enough that you could retard the ignition a degree or two extra and bump the fuel a little rich and head down the road with autotune on safely at 7 psi. Atleast that's what I did.

magnamx-5 09-30-2007 09:10 PM

just use a reverse helper spring problem solved. With that i was able to run 5 psi on a 12 psi can.

y8s 09-30-2007 09:18 PM

CHICKENS! all chickens!

how about not flooring it until it's tuned. you shouldn't really drive it until it is anyway. but not flooring it will keep you from full boost.

but leaving the WG open is fine. more importantly: what do you care if you build boost fast or not if the car's not tuned properly?

Arkmage 09-30-2007 10:47 PM


Originally Posted by cjernigan (Post 158005)
Depending on what EMS you're using, the megasquirt base maps we have available are pretty damn close for just about any car. Close enough that you could retard the ignition a degree or two extra and bump the fuel a little rich and head down the road with autotune on safely at 7 psi. Atleast that's what I did.

That's what I was planning on doing... I think Brainiack's S60 1.6L will be fairly close to my 1.8L with saab T3. I'll probably hit boost a bit lower, but will run out of steam in the top end so his map would have me pretty dang rich in the upper end. Figured I'd dial back the timing 4-5 degrees, and go to town on it.

Once I get it tuned in "safe" then I'll hit up BEGi for some dyno tuning for power.

cjernigan 09-30-2007 11:04 PM

I am using DIYautotune's timing map with no indicated knock fwiw. Their map is already retarded some from their dynotuned car. As for fuel, it doesn't really matter because you'll be tuning it realtime anyway. Just keep it from going lean.
Man it's cool there are so many going MS.

jay526 09-30-2007 11:20 PM


just use a reverse helper spring problem solved. With that i was able to run 5 psi on a 12 psi can.
could you explain this alittle more? I assume you mean replacing the spring inside the actuator.

magnamx-5 09-30-2007 11:32 PM

2 Attachment(s)
No take a spring and clamp it to the rod attach the spring to a plate or something away from the actuator and the force of the spring will pretension the WG allowing you to dial back boost as far as you like.
Attachment 215761 mine was even adjustable cause of my threaded eye hook on one end
Attachment 215762

jay526 09-30-2007 11:42 PM

Cool. Thanks.

Braineack 10-01-2007 07:55 AM

Richard I love your "brace" :gay:

magnamx-5 10-01-2007 02:41 PM

If you like i can make one for you to i still have the original. ;) lemme know.

Newbsauce 10-01-2007 03:48 PM

I for one just think not flooring it is a great idea until your ready to man up and go for >7 psi. :)


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