Before I mucked around under the hood, I used to get 33psi with my 12v reliably and repeatably. Never spiked, never buried the gauge as long as the boost line was hooked up to the wastegate control.

I've now swapped in a P-pumped 24v and I'm overboosting at and near WOT when under load.

I only have a 35psi gauge and it'll pin it - probably getting to 45+psi. Stock gasket and retorqued stock bolts to 130# with roughly 17˚ effective timing; I can't boost that far safely. I'd like to be back to 30ish psi peak boost. I'm still giving manifold pressure to the wastegate, and I actually just stepped up line size from 1/4" to 5/16" but it didn't make a difference.

What I changed:

- nothing at all on the turbo side. same turbo, same wastegate actuator, nothing dropped nothing adjusted nothing intentionally tweaked...

- the boost line is now about 2' longer since it needs to run around the one piece valve cover instead of between #3 and #4.

- manifold pressure source and routing changed.

before:

1/8" NPT port in head to boost gauge

1/8" NPT port in head to tee, unrestricted to 1/4" line to wastegate; restricted port to AFC

now:

1/4" NPT port in intake horn to 5/16" line to wastegate

1/8" NPT port in intake horn to tee, unrestricted to boost gauge and to AFC

One other difference is I have lost smoke - it used to smoke badly off the line until 1300-1400, and now it does not at all, but timing is at least a little different now.... I didn't open the AFC during the swap so star wheel, idle screw and fuel plate (#100 home ground) settings should all match. Only difference should be 1-2˚_timing. It now acts exactly as it should with a well tuned AFC: no smoke off the line, and it doesn't start to overfuel until about 2500rpm and WOT. I think I actually need to move my fuel plate back a little as it'll get hot up there, but I need to get the overboost taken care of before I can tune the top end.

How can I restrict my boost?

Hook up with ISX he's created a boost regulator that actually works rather well for his 12V 97...

It will probably take tweaking the WG a bit to get it where you want. The 24V head moves a lot more air, so your getting more drive air, which makes more boost, which makes more drive air. It will probably take more pressure to the WG, or less preload on the WG to equalize your boost. The loss of smoke is also probably due to the increased airflow from the 24V head, thats a good thing!

Didn't you say on another thread there was some sort of boost elbow on that 24V? 1-2* timing difference will change the WOT boost you see but to the point of only 1-3psi. The 24V head has more flow but not to the point of creating over 10psi more boost with the same ppump that produced 33psi in the 12v. I have seen the CFM values and there is nothing to go overly nuts about. Even if it did have the flow, it still needs fuel to create the heat/expansion needed for flow, and there would be a hell of a lot more flow for that much more boost, which means a hell of a lot more fuel. I am betting that elbow is a boost elbow, or the wastegate on that 24V is not functioning right. I hit 33psi with the wastegate open, but I hit over 45 as well with it blocked. You can take an air compressor and stick in the wastegate line and see when the wastegate opens, or if it opens. Look at that boost elbow thing and see if there is a tiny hole in it or something, or tell me if you even have a boost elbow.

Without a different pressure guage its only speculation its boosting to 45, it could be going to 36 for all we know. Really need to get a 0-60 on there.

You can take an air compressor and stick in the wastegate line and see when the wastegate opens, or if it opens. Look at that boost elbow thing and see if there is a tiny hole in it or something, or tell me if you even have a boost elbow.

thats a good idea

the gauge doesn't peg until 5-7psi past the 35 mark, and it'll peg hard if I let it. It's not 36, it's 40+ without a doubt. And even if it was only 36 that's 3-5 more than I want :)No boost elbow - I have a 1/4" NPT to 5/16 inverted flare screwed into my intake, running 5/16 brake line right to the WG controller. No restriction or bleed off. And no change from when I had a different hunk of 1/4" brake line making that same run - it's all been removed, inspected, and reinstalled. Twice now since it was just off doing my injection line swap.I'll get some shop air on it next week and see if something went haywire with the WG control. Making a trip to VA tomorrow.... I'll be home Sunday and caring much more about my broken cruise :banghead:

You need to do a boost leak test. What kind of boost controller are you running? Make sure the DIP switches or whatever it uses are set up correctly for your WG type.I was using a Greddy Profec B and forgot to change the DIP when going from internal to external gate...i gave up on that thing for years before it just clicked one day.when in doubt, get the instructions out!

You need to do a boost leak test. What kind of boost controller are you running? Make sure the DIP switches or whatever it uses are set up correctly for your WG type.

:lmao: This is a P-pumped truck, no DIP settings to screw with on this bad boy! Boost line from the intake horn over to the WG actuator on the bottom of the turbo. Have done 1/4" line and 5/16" line, no change. I still haven't hit it with shop air to make sure it moves. Turbo will probably be coming off for Banks Brake install sometime soon anyway so I'll muck with it then. I just pedal it on the hills for now with a load. I had a bad boost leak with my old rotten intake cover. That should be fixed as of yesterday - but if anything that should give me more not less air!

I've finally gotten around to my Banks Brake/4" exhaust project, so I had the back of the turbo off last night. The gate isn't frozen and moves smoothly. I didn't disconnect the pressure line to it to test with shop air yet but I'm expecting that this is something I can either take care of with a linkage adjustment, or that there's an issue with the actuator.I'll update this thread when I pull that line off and see if the diaphragm is blown.

I'll update this thread when I ... see if the diaphragm is blown.

Thoroughly blown. Doesn't stop airflow at all. Ran 70psi through it and the rod didn't move at all. Definitely shot. Just need to scare up a replacement now and hope it doesn't cost the $150 of the Banks stuff that a quick Google gave me, and that I can set it to a happy 30-32psi again. Oh, and figure out how to get it off. Hoping I don't have to pull the turbo.

Thoroughly blown. Doesn't stop airflow at all. Ran 70psi through it and the rod didn't move at all. Definitely shot. Just need to scare up a replacement now and hope it doesn't cost the $150 of the Banks stuff that a quick Google gave me, and that I can set it to a happy 30-32psi again. Oh, and figure out how to get it off. Hoping I don't have to pull the turbo.

This should help you out. Skip to 1:30. Basically you just take the snapring thing off the wastegate arm (first thing I did in the video) then you just take those 3 bolts out (yours won't be allenhead). Make sure and use a lot of penetrating oil on those bolts first, I think those bolts came out fine and it's the exhaust housing cover bolts that were all tweaked and broke off so you shouldn't have any problem, but penetrating oil ensures it. There are spacers on all the bolts so make sure you know where they went, take a quick pic of it if you have to (otherwise, I got a million pics of it).

http-~~-//www.youtube.com/watch?v=38_QeCreY3g