08:27:03am, Thursday, May 02, 2024
Under turbo at end of pull
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Anonymous User
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I pull in a light pro class. 525 cubes with PPump, 5 X 25 dual feed injectors. 2 water ports on crossover and one in front of turbo. Have a 3.15 in and 3.6 out. I put the latest and greatest turbo compressor in and have increased boost from 70 to 80lbs. However, at the end of the pull I'm not spinning out as I was with the other turbo wheel in the same gear, it snuffs. The head is a big valve head ported to 320cfm. Pump timing is at 40 and valves are set at 18.
Any thoughts on how to overcome this issue would be helpful. Thanks |
Re: Under turbo at end of pull
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egor
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what size exaust housing |
Re: Under turbo at end of pull
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Anonymous User
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25, this is the smallest I believe. It is an HX 60 |
Re: Under turbo at end of pull
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simular problem
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we were having a simular problem. 80 lbs out of the hole and down the track but snuffed it everytime. we ended up changing the wheel. one less on the intake and one more on the exhaust and that did the trick. im assuming u are open rpms? |
Re: Under turbo at end of pull
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Anonymous User
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Yes open RPMS. Since this is the latest and greatest wheel at 3.15, is there anything you can do with fuel, air, timing, etc to help? Thx |
Re: Under turbo at end of pull
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I've similar ? what size turbo should I use 401 stock, 12mm simms with injectors. 3200 rpm max . thinking s300[ 2.4in 2.6 out] or[2.6 in 2.8out]maybe small s400 . not exact subject, but I could use help. thanks in advance and thanks morgans |
Re: Under turbo at end of pull
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Anonymous User
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Not an expert by any means, but I would go smaller because your limited on rpms. |
Re: Under turbo at end of pull
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mx335
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I would think the 25 exhaust houseing would be the right one for a 525 . They do make smaller ones a 22 and a 19 you mite want to try the 22 . R u useing the stock exhaust manifold? |
Re: Under turbo at end of pull
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Anonymous User
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yes, it is stock. Before I updated the compressor wheel, I was spinning out at the end. I have direct and 3 gears under that are 6% less by each gear. I could drop one more gear, but I would lose wheel speed. I would think the 25 would be fine as well. What about a bigger out? Thx |
Re: Under turbo at end of pull
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CPR
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Far from an expert, but bigger exhaust ought to exacerbate the problem. Think about blowing through a straw. High velocity that can knock over light objects you direct it at (like a turbine wheel). Try the same with a 3" pipe and you won't even tussle anyone's hair. As your motor loads up at the end and rpms fall, the pressure in the intake overwhelms whats pushing on the exhaust side, so it stalls. A smaller exhaust will potentially hurt you for max HP, but keep it lit late. The other option, as mentioned, is to alter blade counts. 1 more exhaust will provide another surface for the remaing exhaust pressure to push against, one fewer intake is one less surface for low-rev boost to push back on. In a sense, on the intake side, the less efficient compressor is actually better becuase it's stall speed will be lower.
Hope this helps and if I'm wrong, please correct me so we're all smarter, LOL! |
Re: Under turbo at end of pull
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Could Be
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How much water and fuel are you at. |
Re: Under turbo at end of pull
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Anonymous User
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How a simpson valve set up with a 24 and 28 nozzle in the crossover and a 18 in front of turbo. Don't know exact quantity of water used per fun. Fuel is around 575. Thx |
Re: Under turbo at end of pull
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Registered: 03/26/2008 Posts: 214 |
sounds like you need more fuel and water. I run a 460 ci with a 3x3.6 hx60 and have fuel set at 850cc and 55oz water in 15sec. and run a 32 housing and spin out at end with a 19-1 gear ratio. Do you have data aquisition computer. I was at 700cc and 40cc water and added fuel and water till exhaust temp started cooling off |
Re: Under turbo at end of pull
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al
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I use a gt 42 with 101 housing and 2.8 intake, slugged down to 2.75. Runs pretty good |
Re: Under turbo at end of pull
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yeah
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Put the old setup back on. |
Re: Under turbo at end of pull
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Not an expert
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Untill you have a data log and port water injection and get your cylinder temps, its a shot in the dark. you could be drowning the engine or a couple cylinders. |
Re: Under turbo at end of pull
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Anonymous User
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My exhaust gas temp's are around 1530 |
Re: Under turbo at end of pull
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Wondering
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What is the common fuel and water setting range for these IH smaller cube tractors with 3 inch turbo, p pump, open rpms. |
Re: Under turbo at end of pull
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RPMS
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what kind of rpms are you turning down the track |
Re: Under turbo at end of pull
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Anonymous User
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Taking off at 5,000. Haven't looked but I think between 3500 and 4000 |
Re: Under turbo at end of pull
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Not an expert
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Your checking all your cylinder temps combined, 1 may be 1800,1 may be 1100 untill you can read each 1 its a shot in the dark. |
Re: Under turbo at end of pull
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Anonymous User
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Ok, thanks |
Re: Under turbo at end of pull
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Housing
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Smaller housing on turbo |
Re: Under turbo at end of pull
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anotherpuller
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What does your smoke look like? is it thinning out or gettin gray or coal black? 575 fuel dont seem like near enough & it could probably use more timing assuming that you're checking it with a light off the fuel line. What kind of cam does it have? data loggers are great but its not a complete shot in the dark without one, it can be figured out. |
Re: Under turbo at end of pull
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Anonymous User
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Thanks. Pump is at 40 and cam at 98. Lobe centers are 106. It is a vogel cam with 242 exhaust and 220 intake durations. My egt's are around 1530ish. Smoke is still a little more black than grey. Any help is appreciated. |
Re: Under turbo at end of pull
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hey now wait a minute
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have you checked your exhaust fins on the outer edge of the wheel. If they are burnt off any, it will do just what you are saying it is doing. |
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