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Discussion Starter #1 (Edited)
This is my first post. I'm new to the mustang world, i have a problem i hope someone can help me with. i have a 1992 5.0 lx with a 67mm turbo with a 44mm wastegate that bottle necks into a 38mm blowoff. the engine is compleatly stock with 42# injectors. When i bought the car it had the turbo on it. I had it tuned with a SCT chip. The first time i had it tunned i was running 10psi of boost. I had it tuned again a month later with the next size spring (the 13psi spring). at the dyno i was still pulling 10 psi. I took it to the track 4 days later, and it all of a sudden started runnung 11.5 to 12 psi. Now at full load the engine has a hesitation at high rpm's (4500 and up). I checked the plugs and there gap I gaped them at .034. The plugs where white like the car is running lean. I think since the boost went up the car is running to much air not enough fuel. if anyone has any suggestions on my problem please write back. i think i need to take it back to the dyno and have my fuel adjusted.
 

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umm I ran 10 psi on my stock motor and dropped it back down to 8psi so I wouldn't toast the block since I daily drive it but 12 psi i'd be a little hesitant on racing it until I got at least the boost control worked out and tuned down to what boost level the tune was for before you have a anchor of an engine.

Buy and install a wideband o2 and see how lean you are or get it dyno tuned at that boost level to a desirable afr
 

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I think your detonating. Meaning your not getting the proper fuel and or spark mixture. What fuel pump and what grade of gas are you using?
 

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You answered your own question. The car has a 13# spring and is tuned for 10#. Now it's on 12.5#. That means alot more air and the same amount of fuel.

Btw a bigger gate and a smalle bov isn't a bottle neck. A bigger get is to keep boost down and is on the hotside. The bov is on the cold side. NO real link.
 

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You may also be getting spark blow out. But your gapped pretty tight. I'd def get the boost down to 10 psi though.
 

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Discussion Starter #7
Turbocharged 5.0 hesitating at high rpms

Thank you for your posts. I'm pretty new at all this. So any info I can get is much appreciated. I know I pretty much answered my own question, but I wanted someone to validate my hypothisis. Thank you again.
 

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First thing first get a wideband. Every boosted car should have one that's modded. I'm sure the stock pump is pushing enough fuel , you would need atlease a 255lph. Also your more than likely getting spark blow out try regaping the plugs lower. What BOV and what WG are you using?
 

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Discussion Starter #12
Using a tial 44mm wg and 38mm blow off. I'm guessing it's a stock fuel pump. I never removed it and looked at it. Running 377rwhp 452rwtq. How much realistic boost can this block handle, and how much hp and torque is max?
 

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I'm guessing it's a stock fuel pump. Haven't had a reason to take it out and look at it.
It's not a stock pump, you're guessing wrong. A stock pump would not have gotten you to 370+ boosted hp. A stock pump won't supply 300+ n/a hp. Just figure out what pump you have so you can post up and make sure you have enough.
Second point, the reason you didn't get more than 10 psi on the dyno is probably because the dyno didn't have a load cell on it. You need a load cell on a turbo car so the engine can be loaded so that it will see full boost. A load cell electronically creates a resistance requiring more effort from the engine to turn the drum on the dyno. It causes the engine to see a higher load and therefore full boost. Increasing the load the dyno produces step by step until the boost does not increase anymore will allow you to find out how much total boost the engine can produce and allow you to tune the spark and fuel ratio for it.
 

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Hmmm never seen a turbo car make less boost on loaded dyno vs. a dynojet?

Regardless, there has to be a 255 in there, but I assume you have some sort of fmu rigged up if your posative you have the stock injectors.

Get 42lbers, 80mm blowthrough, and a fresh tune on 12psi and shoot for 400 at the tires. Car has potential.
 
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