Hey everyone, I’m experiencing some boost creep and want some opinions of my setup/wastegate size and or location. I’ve got a mopar 360 forged pistons about 9.5-1 compression, Eagle I beam rods, a bullet flat tappet cam, stock iron heads. 2” hotside and 3” down pipe. Precision 46mm wastegate and a tial 50mm BOV. Among a couple other issues I’m having I noticed this. I was beating on it and it blew the intake tube off the turbo, I limped it back home and checked the data log and found that it spiked after I got out of the throttle. Here’s the data it reached 17.6lbs @ 4500 rpm and then up to 23.5lbs @ 3700 rpm. Here’s some photos as well as the log.

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Your gate placement isn't good. If it were lower on the merge, and more vertical it would be much better. We need more info. What spring in gate? A boost spike on decel with throttle closed is odd. Is that Fitech?

 

Sorry I thought I put that in there. I started off with a 6lbs spring in the gate. Yes it is currently on a Fitech system.

 

I would look check your gate function, somethings not right. Your 17, and 23 psi were both at 50 % tps so that tells me it was just a load thing. Your gate placement isn't bad enough imo to have that much boost at that rpm with a working gate, and 6 psi spring. What turbo?

 

How is your gate reference plumbed?

Very cool car btw, I love that body style.

 

dang it! Sorry I wrote all this out and had all that info in there went out of the browser to look at something else and it was gone. Lol. It’s a VSRacing billet 78/75 .96 AR. I could be an idiot and have it hooked up wrong but I’ve got a nipple from the turbo housing to the lower nipple on the gate. I understand this is how it should be set up with just relying on the spring to regulate the boost pressure.

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That's correct. Are there any extra ports on the lower half of the gate that could be open yet? I don't know precision, but tial has multiple ports. If that all looks good, you need to bench test it.

 

I will have to check. Just got my nuts ✂️ So I’m taking it easy for a few days. So to bench test it I would just apply pressure to that same hose to see when it opens correct?

 

If the boost pressure is being referenced in front of the TB then it would measure a boost spike when you close the throttle.

Either way when you close the throttle quickly while boosting the pressure builds up in the intake tubes and can blow them off. If the boost is spiking then I would look at the blowoff valve to make sure it's functioning properly. The BOV is supposed to release any pressure in the intake charge tubes when the throttle is closed so the tube's shouldn't blow off.

ks

 

looks like just the one.

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Yes. You could just apply air to it while its on the car just to check for leaks as well. Dumb question, but many of these gates come with multiple springs, did you verify it had a 6 psi spring?

 

I have been wondering if I’ve got the BOV hooked up correct or not. It’s going to the 3/8 nipple at the back of the Fitech unit.

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yes I opened it up and changed the spring based off their chart included with the instructions.

 

His map is in the Fitech, so definitely post throttle, and the spike was at 50% throttle opening so bov wouldn't function.

 

It looks like the gate may have two lower ports. You may get lucky, and that's all it is. The gate should have come with two banjo's and a plug from what I can see.

Edit... The pic you posted actually shows them both.

 

Any port below the throttle blades will work for the bov, so that's correct.

 

Precision gates on mine,they have 2 ports on the lower.

 

You are correct sir there’s another port I’ve got that’s wide open. Thank you. So this should take care of the issue or at least help the issue.

 

You'll be good.

The gate should have come with a plug.

 

Thank you for your help guys!!