Miata Turbo Forum - Boost cars, acquire cats.

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Techsalvager 08-23-2010 06:45 PM


Originally Posted by faeflora (Post 620173)
Wow, that's great, sounds like a piece of cake to design and implement. Yah.

Techsalvagar, do you have any details or pics of your setup? Parts etc?

nothing yet, I've still to figure out what turbo I want to go with.
I will need a turbo with a carbon seal to keep oil from being sucked out of the turbo.

Right now I"m working on my engine managment part. It can do fuel if I wanted to do that, but I really want to get it doing both fuel and spark, unfrountaly I have a problem with spark output. Spark breakup is happening

I'll probably use a stock TB, rip out the butterfly and the IAC, plate off the sides and the iac area.

time to get the parts, just scan the stuff slowly for deals, etc, also need to get the car in nicer shape before turbo, new motor mounts, bushings, etc


Just posted incase anyone knew off hand or had an idea.

braineack is knows I'm crazy

astroboy 08-23-2010 07:17 PM

With that setup there would be a high level of suck if the tb fell apart.

IcantDo55 08-23-2010 10:50 PM

Subscribing.

Cococarbine3 08-23-2010 11:41 PM

What would happen if you close the throttle while the compressor is spinning at 100,000rpm? Instead of compressor pressure surge would there be something like a vacuum surge between the throttle body and turbo inlet?

Like for instance say as soon as you close the throttle, there is 200kpa post turbo and 0kpa before. Is that a problem or does the engine quickly suck that 200kpa up.

From what I have been reading, 2 throttle bodies are recommended, 1 before, 1 after, because there is a fraction of a second delay of power reduction when the throttle is closed

fooger03 08-24-2010 08:28 AM

The twin throttle bodies is nearly a paradox. (Not quite, but nearly)

You want a second throttle body to better regulate your off throttle engine operation, but adding the second throttle body quickly negates the effect you're going for regarding spinning the compressor in a vacuum...so as soon as you add the second throttle body, the entire setup defeats its own purpose. (Well, there will still be a vacuum, but the vacuum wont quickly form off throttle)

You might want to figure out how to route the Idle air control valve in such a way that the idle air doesnt pass through the turbocharger. Possibly mount a second throttle body at the intake manifold without a throttle plate/tps/etc, and use it soely for idle air control through the external air intake port, then remove the idle air control assembly from the pre-turbo throttle body. Just gotta figure out a 1-way valve setup for the assembly to keep boost from getting out to atmosphere through the idle air control.

Joe Perez 08-24-2010 12:46 PM

A lot of carburetted turbo setups were of the draw-through variety, where the turbo (and thus, the throttle) were located at the inlet to the compressor.

One common problem with this arrangement was that when the throttle plate was slammed shut at high engine RPMs, the resultant vacuum present inside the compressor tended to cause the oil seals to blow out, or at least leak severely.


What will happen when running at partial throttle under load? Will the compressor be trying to run at a very high PR with a very low mass-flow? That would push you up and to the left on the map, beyond the surge line.

Techsalvager 08-24-2010 01:00 PM


Originally Posted by fooger03 (Post 620541)
The twin throttle bodies is nearly a paradox. (Not quite, but nearly)

You want a second throttle body to better regulate your off throttle engine operation, but adding the second throttle body quickly negates the effect you're going for regarding spinning the compressor in a vacuum...so as soon as you add the second throttle body, the entire setup defeats its own purpose. (Well, there will still be a vacuum, but the vacuum wont quickly form off throttle)

You might want to figure out how to route the Idle air control valve in such a way that the idle air doesnt pass through the turbocharger. Possibly mount a second throttle body at the intake manifold without a throttle plate/tps/etc, and use it soely for idle air control through the external air intake port, then remove the idle air control assembly from the pre-turbo throttle body. Just gotta figure out a 1-way valve setup for the assembly to keep boost from getting out to atmosphere through the idle air control.

Check valve to shut under pressure. and to open under vacuum.

That way it doesn't throw off MAF readings

Techsalvager 08-24-2010 01:05 PM


Originally Posted by Joe Perez (Post 620692)
A lot of carburetted turbo setups were of the draw-through variety, where the turbo (and thus, the throttle) were located at the inlet to the compressor.

One common problem with this arrangement was that when the throttle plate was slammed shut at high engine RPMs, the resultant vacuum present inside the compressor tended to cause the oil seals to blow out, or at least leak severely.


What will happen when running at partial throttle under load? Will the compressor be trying to run at a very high PR with a very low mass-flow? That would push you up and to the left on the map, beyond the surge line.

great question, more research needed, appreicate it.

fooger03 08-24-2010 01:09 PM


Originally Posted by Joe Perez (Post 620692)
What will happen when running at partial throttle under load? Will the compressor be trying to run at a very high PR with a very low mass-flow? That would push you up and to the left on the map, beyond the surge line.

I was under the impression that this could be partially solved with a properly setup TPS based EBC.

Techsalvager 08-24-2010 01:20 PM


Originally Posted by fooger03 (Post 620717)
I was under the impression that this could be partially solved with a properly setup TPS based EBC.

I think it maybe possible as well to solve it like that.

04SILVERSI 08-24-2010 01:57 PM

Your doing a less efficient design of this

http://www.aerocharger.com/index.php

http://www.engineeringtoolbox.com/fa...rol-d_198.html
and
http://www.epa.gov/apti/bces/module5.../principle.htm
this explains how inlet vanes move you on a map.

I say go for it if you have turbos to spare. Have fun and maybe you can come up with a good results.

Techsalvager 08-24-2010 02:18 PM

I'm aware of those, they are alos 2k a turbo and up

Full_Tilt_Boogie 08-24-2010 09:14 PM


Originally Posted by 04SILVERSI (Post 620756)
Your doing a less efficient design of this

http://www.aerocharger.com/index.php

http://www.engineeringtoolbox.com/fa...rol-d_198.html
and
http://www.epa.gov/apti/bces/module5.../principle.htm
this explains how inlet vanes move you on a map.

I say go for it if you have turbos to spare. Have fun and maybe you can come up with a good results.

thats not doing the same thing at all

I also question your definition of "efficiency"

Techsalvager 08-25-2010 07:59 PM


One common problem with this arrangement was that when the throttle plate was slammed shut at high engine RPMs, the resultant vacuum present inside the compressor tended to cause the oil seals to blow out, or at least leak severely.
Joe do you know if these were stock setups or aftermarket. From what I've read and learned you need a Turbo with a carbon seal to keep oil from leaking out if the compressor will see vacuum.


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