Under turbo at end of pull August 01, 2011 05:03AM
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
Reply Quote

Re: Under turbo at end of pull August 01, 2011 05:12AM
what size exaust housing
Reply Quote

Re: Under turbo at end of pull August 01, 2011 06:06AM
25, this is the smallest I believe. It is an HX 60
Reply Quote

Re: Under turbo at end of pull August 01, 2011 06:47AM
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?
Reply Quote

Re: Under turbo at end of pull August 01, 2011 06:57AM
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
Reply Quote

Re: Under turbo at end of pull August 01, 2011 06:58AM
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
Reply Quote

Re: Under turbo at end of pull August 01, 2011 07:16AM
Not an expert by any means, but I would go smaller because your limited on rpms.
Reply Quote

Re: Under turbo at end of pull August 01, 2011 08:09AM
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?
Reply Quote

Re: Under turbo at end of pull August 01, 2011 08:50AM
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
Reply Quote

Re: Under turbo at end of pull August 01, 2011 01:20PM
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!
Reply Quote

Re: Under turbo at end of pull August 01, 2011 01:23PM
How much water and fuel are you at.
Reply Quote

Re: Under turbo at end of pull August 02, 2011 12:24AM
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
Reply Quote

Re: Under turbo at end of pull August 02, 2011 12:43AM
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
Reply Quote

Re: Under turbo at end of pull August 02, 2011 02:22AM
I use a gt 42 with 101 housing and 2.8 intake, slugged down to 2.75. Runs pretty good
Reply Quote

Re: Under turbo at end of pull August 01, 2011 03:29PM
Put the old setup back on.
Reply Quote

Re: Under turbo at end of pull August 02, 2011 12:42AM
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.
Reply Quote

Re: Under turbo at end of pull August 02, 2011 01:22AM
My exhaust gas temp's are around 1530
Reply Quote

Re: Under turbo at end of pull August 02, 2011 01:52AM
What is the common fuel and water setting range for these IH smaller cube tractors with 3 inch turbo, p pump, open rpms.
Reply Quote

Re: Under turbo at end of pull August 02, 2011 02:38AM
what kind of rpms are you turning down the track
Reply Quote

Re: Under turbo at end of pull August 02, 2011 04:54AM
Taking off at 5,000. Haven't looked but I think between 3500 and 4000
Reply Quote

Re: Under turbo at end of pull August 02, 2011 04:29AM
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.
Reply Quote

Re: Under turbo at end of pull August 02, 2011 04:54AM
Ok, thanks
Reply Quote

Re: Under turbo at end of pull August 03, 2011 07:55AM
Smaller housing on turbo
Reply Quote

Re: Under turbo at end of pull August 04, 2011 02:04AM
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.
Reply Quote

Re: Under turbo at end of pull August 04, 2011 04:59AM
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.
Reply Quote

Re: Under turbo at end of pull August 04, 2011 05:45AM
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.
Reply Quote

Newer Topic Older Topic

Author:

Your Email:


Subject:
Spam prevention:
Please, enter the code that you see below in the input field. This is for blocking bots that try to post this form automatically. If the code is hard to read, then just try to guess it right. If you enter the wrong code, a new image is created and you get another chance to enter it right.
Message:
Website Statistics
Global: Topics: 38,670, Posts: 229,762, Members: 3,327.
This forum: Topics: 37,076, Posts: 225,938.

Our newest member JD_8520