4.3L turbo is DONE! Now i need to figure out the boost spikes and A/F.
08-03-2005, 08:56 PM
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4.3L turbo is DONE! Now i need to figure out the boost spikes and A/F.
Well, its finnaly done. Man is it AWSOME! Its faster at 50% throttle now @7psi than it was with the 75 shot on it.
Now for the down side that I need some help with. With it floored and missing(fouled plugs from the N2O) it runs a fairly steady 5-6psi, but when it shifts BAM it spikes to about 12psi. What is up with this? I have a 40MM wastegate with a 4.86# spring in it so it shouldnt spike like that right?
Also, on the highway at about 55 i can give it about 45-50% throttle and the boost quickly builds to about 7psi, maybe pushing 8. All my boost readings are from the intake manifold. How do I regulate it down to 5-6psi max?
And last, my A/F gauge only is swinging from deep red to orange. It never goes to green, exept earlier today it maxed out green and stayed even at idle. I already bought new O2's and put them in, and the new plugs/wires go on in the morning, but its still not swinging to green like it used to. What could cause this? When i floor it with the new O2's even as soon as i get about 3-4psi it drops into the red and the deep red where its not even registering anymore. Could this bee the bad plugs not burning all the fuel, and the O2 doesnt read unburned fuel?
Anyone with any info, PLEASE help me out.
Now for the down side that I need some help with. With it floored and missing(fouled plugs from the N2O) it runs a fairly steady 5-6psi, but when it shifts BAM it spikes to about 12psi. What is up with this? I have a 40MM wastegate with a 4.86# spring in it so it shouldnt spike like that right?
Also, on the highway at about 55 i can give it about 45-50% throttle and the boost quickly builds to about 7psi, maybe pushing 8. All my boost readings are from the intake manifold. How do I regulate it down to 5-6psi max?
And last, my A/F gauge only is swinging from deep red to orange. It never goes to green, exept earlier today it maxed out green and stayed even at idle. I already bought new O2's and put them in, and the new plugs/wires go on in the morning, but its still not swinging to green like it used to. What could cause this? When i floor it with the new O2's even as soon as i get about 3-4psi it drops into the red and the deep red where its not even registering anymore. Could this bee the bad plugs not burning all the fuel, and the O2 doesnt read unburned fuel?
Anyone with any info, PLEASE help me out.
08-04-2005, 12:01 AM
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Spikes could be caused by a binding wastegate valve, too small of an exhaust housing, too small of a downpipe. They do make 44mm and 46mm tial wastegates, but at your psi, I am not sure if that is over kill or not...
Change your plugs thought, that is a given. Nothing is worse then misfires...
Generally for a turbo, you should always be running rich and under boost never go lead or even stoich.
Change your plugs thought, that is a given. Nothing is worse then misfires...
Generally for a turbo, you should always be running rich and under boost never go lead or even stoich.
08-04-2005, 05:30 AM
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Its an auto with a 2600TCI stall. The turbo is a T4 and has the lag to prove it. LOL
I dont think the WG is sticking though, its new, well greased, and moves easily by hand.
The downpipe isnt too small because there isnt one. Its open on the exhaust side.
BTW, what size should i be using for my charge pipe? Right now I have 2"ID.
Also, if its a 4.86# spring i dont need to run the boost line to WG to help open it do I? Thats only if i want to control the boost and up it right?
I dont think the WG is sticking though, its new, well greased, and moves easily by hand.
The downpipe isnt too small because there isnt one. Its open on the exhaust side.
BTW, what size should i be using for my charge pipe? Right now I have 2"ID.
Also, if its a 4.86# spring i dont need to run the boost line to WG to help open it do I? Thats only if i want to control the boost and up it right?
08-04-2005, 05:36 AM
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What kind of guage do you have? If it's an Autometer the reading is almost guarenteed to be off. My Mustang's Autometer guage reads 12-15lbs of boost where my AEM computer with 3.5 bar map is only reading 6-9lbs. I know that doesn't help your spike but it might give you insight into your actual boost reading. In my experiences the Stewart Warner guage is the best calibrated and the same price or cheaper than most.
Are you absolutely sure on the wastegate spring? We've had a few Tials get sent with the wrong spring. Just something else to think about.
Your running completely off the wastegate spring? No boost controller of any kind?
Someone brought up the exhaust housing being too small and that sounds like it could be something to look at. What a/r is it?
I work around and on turbo cars almost everyday and i'm with a very popular turbo shop called Virtual Works. I don't know if you guys follow Supras or anything but we've done quite a few of the fastest and most powerful in the world. I'm just trying to let you know that if i don't know the answer then i'm sure i can find out for you. I've got 3 turbo cars of my own so i know the problems you can run into for sure.
Are you absolutely sure on the wastegate spring? We've had a few Tials get sent with the wrong spring. Just something else to think about.
Your running completely off the wastegate spring? No boost controller of any kind?
Someone brought up the exhaust housing being too small and that sounds like it could be something to look at. What a/r is it?
I work around and on turbo cars almost everyday and i'm with a very popular turbo shop called Virtual Works. I don't know if you guys follow Supras or anything but we've done quite a few of the fastest and most powerful in the world. I'm just trying to let you know that if i don't know the answer then i'm sure i can find out for you. I've got 3 turbo cars of my own so i know the problems you can run into for sure.
08-04-2005, 05:48 AM
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Do you have an intercooler? I can tell you right now that 2" is very very small! If you have an intercooler run the inlet size of the intercooler from turbo to in......out of the intercooler run a size or two bigger or the size of the throttlebody inlet.
If your not running a downpipe that right there will add 1-3lbs of boost. Put an exhaust on there and you'll drop down to a more respectable level. Your a/f will most likely come back to a normal reading as well. This is if you had it tuned with an exhaust and now took it off. It'll lean you out for sure. If you've had it this way then back to the drawing board.
If your not running a downpipe that right there will add 1-3lbs of boost. Put an exhaust on there and you'll drop down to a more respectable level. Your a/f will most likely come back to a normal reading as well. This is if you had it tuned with an exhaust and now took it off. It'll lean you out for sure. If you've had it this way then back to the drawing board.
Last edited by White05Denali; 08-04-2005 at 06:03 AM.
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08-04-2005, 07:29 AM
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there is still a full exhaust including muffler. The turbo is after the muffler and everything. I'm not running any boost controller, just running off the spring. The spring the WG came with was an 18#er so i ordered the 4.86 seperate. Will a boost controller help with the spikes?
White05, the turbo is off a 3.8L I6 diesel. It has the specs on the compressor side, 72mm .50A/R, but nothing on the exhaust side. I do know that i dont get boost till above 2500rpms at all. But from there it builds quick.
White05, the turbo is off a 3.8L I6 diesel. It has the specs on the compressor side, 72mm .50A/R, but nothing on the exhaust side. I do know that i dont get boost till above 2500rpms at all. But from there it builds quick.
08-04-2005, 09:30 AM
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Originally Posted by Snake Eater
White05, the turbo is off a 3.8L I6 diesel. It has the specs on the compressor side, 72mm .50A/R, but nothing on the exhaust side. I do know that i dont get boost till above 2500rpms at all. But from there it builds quick.
I6 diesel????? International??
08-04-2005, 09:43 AM
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Originally Posted by Snake Eater
there is still a full exhaust including muffler. The turbo is after the muffler and everything. I'm not running any boost controller, just running off the spring. The spring the WG came with was an 18#er so i ordered the 4.86 seperate. Will a boost controller help with the spikes?
White05, the turbo is off a 3.8L I6 diesel. It has the specs on the compressor side, 72mm .50A/R, but nothing on the exhaust side. I do know that i dont get boost till above 2500rpms at all. But from there it builds quick.
White05, the turbo is off a 3.8L I6 diesel. It has the specs on the compressor side, 72mm .50A/R, but nothing on the exhaust side. I do know that i dont get boost till above 2500rpms at all. But from there it builds quick.
I'd look into that turbo a little more to see exactly which it is and the specs. Do you know if its a variable vein?
I see now that you've got an STS turbo kit or a similar style correct? I can tell you that i haven't had any experience with that sort of setup. I will ask around today and see what i can dig up. Let me know if you get it figured out though because i'd like to know the culprit.