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Old 06-29-2007, 04:02 AM   #1
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Default Laggy boost?

I had just installed a HKS Manifold with a TD04...

the boost won't come in until 3000rpm with 0.1 bar of boost....and it won't went up to 0.3bar until 4.5rpm....

Does it sounds normal or i have somewhere leaking?

Also, if knocking occurs will the oil pressure bouncing around?

Thanks for the help
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Old 06-29-2007, 05:02 AM   #2
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What are you running for boost control?
What kind of wastegate?
What pressure spring?
Where is the pressure line routed from to the WG? Compressor housing? Manifold?
Which TD04 is it?
Did you take it up to redline? Did you ever get any boost?
Where are you measuring boost? At the manifold?

These are important questions.

If you are getting like 4 psi by 4.5krpms, something is usually wrong with the mechanical portion of the boost control. Probably an open wastegate. I left my WG open once to measure boost creep and I only got up to about 5 psi by redline.

If you have an internal wastegate, is the flapper hooked up to the actuator arm? If you have an external one, is it assembled properly? Did it come with a spring that you perhaps forgot to install?

Another possibility is that the boost signal to the WG is coming out of the compressor housing while you are reading boost at the intake manifold. If your intercooler is restrictive or you have a leak and the wg has a low psi spring, you might only get .3 bar in the intake manifold when it is at full steam. The solution would be to run a vaccuum line from the intake manifold instead of from before the intercooler.

Check out your wasteagte and where your lines are running to and from and let me know.
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Old 06-29-2007, 09:24 AM   #3
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Quote:
Originally Posted by ES86 View Post
I had just installed a HKS Manifold with a TD04...

the boost won't come in until 3000rpm with 0.1 bar of boost....and it won't went up to 0.3bar until 4.5rpm....

Does it sounds normal or i have somewhere leaking?
stock exhaust? size of DP? condition of cat?

Quote:
Originally Posted by ES86 View Post
Also, if knocking occurs will the oil pressure bouncing around?
90-94 US will...
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Old 06-29-2007, 10:28 AM   #4
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It's a internal wastegate, no MBC or EBC yet.
It's a TD04 that comes with my HKS kit which have a triangle flange.

As stated, i can take it to redline with 0.3bar of boost start from 4.5k rpm and 0.1bar from 3000rpm, not making any boost under 3000rpm.

Also, i can heard that there's some metal rattling sound in the turbo....would it be the wastegate not propely closed?

2 1/4 exhaust all the way, No cat.

My engine bay pics if it helps


If you guys need more pic i can post more.
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Old 06-29-2007, 10:49 AM   #5
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yeah, tighten the wastegate rod if possible. I have a feeling your allowing boost to bypass the turbine, slowing the spool. If possible slap a cheap MBC on there as well. Set it to achieve the same Bar, but you'll again notice decreased boost threshold.
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Old 06-29-2007, 11:03 AM   #6
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Why would slap on MBC on there will solve the problem?

Which side should i tighten the rod?

Here is a picture of the WG rod of my turbo

Cureently i moved it to the far left in the picture(when i take the picture it's at middle/neutral)....does it sounds correct or the other way round? Also when i removed the rod, thats only a little of free play(around 20-30degree)....How many free play should be there?

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Old 06-29-2007, 11:13 AM   #7
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the MBC make it so the wastegate doesnt open until the last possible second. the more exhaust spinning the turbine the best for spool. if 1psi is causing the wastegate to open slighty, then there just that much gap in the wastgate where exhaust bypass the turbine so the spool is slowed.

you want the arm to pull very tight against the pin. so you'll want to shorten the rod. to the point where you have to slightly extend the rod out of the actuator to put it back on the rod. Becareful not to spin the rod within the can, only the top half.
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Old 06-29-2007, 11:19 AM   #8
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so does it mean i extend the rod instead of shortern the rod, i am actually let the boost bypass the turbine?

If my wastegate wasn't closed properly before boost, will adding a MBC fixing the problem?
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Old 06-29-2007, 11:32 AM   #9
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so you'll want to shorten the rod. to the point where you have to slightly extend the rod out of the actuator to put it back on the rod. Becareful not to spin the rod within the can, only the top half.
read above.

in the least, at this point, just try shortening the rod.

------------------------
on MBC:

think about it this way. the line from your boost source to the wategate actuator is open. so when you start to make boost, that pressure is starting to push against the actuator. Which will slowly start to open the wastegate. When it does this your spool is effected because a small percentage of the exhaust is being bypassed before you've reached you target.

the MBC is typicaly a ball and spring. You set the preload of the spring so that it's pushing against the ball. When you start making boost, the pressure has to build up agianst the ball before it opens. In the meantime the wastegate stays fully shut. Once the preload of the spring is overloaded the signal can now enter the actuator. I then opens to your target level exactly where you wanted it to.

Because the wastegate was held shut longer, your spool time will decrease, as the exhaust was fully spinning the turbine untill you've reached you boost target. Even at the same .3bar.
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Old 06-29-2007, 12:03 PM   #10
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Make sure you don't have an exhaust leak between the turbo and manifold.
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Old 06-29-2007, 06:31 PM   #11
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The WG arm should pull the flapper up tight against the opening in the turbine housing. The pressure flowing into the diaphram will cause the arm to push out and let it open.
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Old 06-29-2007, 08:40 PM   #12
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when i have laggy boost, i use a shot of nitrous
but its not such a good advise in your case
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Old 07-01-2007, 07:27 AM   #13
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tightening the rod doesn't make a difference.....strange...

Will put on a MBC later on..
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Old 07-02-2007, 11:34 AM   #14
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also will other cars dump pipe fit on miata? like those from 180sx..etc
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