| Author |
Message |
Greg Peterson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 18, 2006 - 12:45 am: | |
Looking at the 92 service manual I see there are these two methods of controlling excessive smoke on a turbo charged 92 engines (Rack delay or a fuel modulator). The fuel modulator looks like it might be superior in that it uses actual pressure from the turbo charger to control the rack delay.
My 8v-92ta is slow on the take off until it gets going. I thought this might be because of the 400hp rating. I have new information from a friend that a bus with a 475hp 8v-92 acts the same on take off.
My engine does not smoke at all. Maybe the rack is set for to much delay since it was a California bus.
Does anyone know if the fuel modulator is better and if so can I replace the rack delay with it?
I could just take off the delay but it would probably smoke to badly.
This is one area of performance that I bet the DDEC wins.
Thanks for any info |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 18, 2006 - 1:28 am: | |
The toughest part of offering advice to a new bus owner, is
with the fact that the owner may have never driven a bus before.
Sooooo....
1. There isn't any such thing as a "fast take-off".
2. The only time you "overcome" another vehicle, is
a. when they're stopped.
b. when they're aside the road with a flat.
3. Economy is:
a. when the group you're carrying buys you lunch.
b. when the tip is more than two hour's pay
4. Speeding is when you:
a. Get there before the group expected
b. When the trooper says you were.
If you think like a bus driver, you'll appreciate your bus much more. |
Phil Dumpster2
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 18, 2006 - 5:10 am: | |
On the other hand, the delay can be truly annoying when you are starting out on a hill, or when you are trying to position the coach on ramps so you can safely work underneath it or put snow chains on the outer duals.
I'd rather not have the delay but put an opacity sensor into the exhaust stream and monitor the emissions via a gauge on the dash and the view out of the mirrors. |
Geoff (Geoff)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 18, 2006 - 7:05 am: | |
I replaced my 350 HP 6V92TA's throttle delay with a fuel modulator and recommend the upgrade to everyone. The fuel modulator gives you instant throttle respnonse up to 3/4 of rack travel, when the turbo boost comes up it gives you the last 1/4. You solve the overfueling problem (black smoke) of accelleration without the annoying slow response of a throttle delay.
--Geoff
'82 RTS AZ |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 18, 2006 - 9:02 am: | |
I've got over-size injectors on mine, and no throttle delay or
modulator. It's tough to control the smog on take-off.
After reading Geoff's and Phil's posts, the modulator seems
the best way to go! The throttle delay can result in aggravation,
if you don't like waiting for the bus to go after you stomp on
the pedal.. It'd be nice to see the cars behind me when I pull
away from a traffic light... |
Steve (Steve)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 19, 2006 - 8:06 am: | |
Hey Greg; I had Detroit remove the delay valve and install all new valve train. rockers, injectors to the N- 90's, advance the timing to 15 degrees,adjust the governor,set the rpm at 600 to 3800, check the compression 510lbs +/- 2 lbs, check turbo and blower air box pressure. We found the exhaust back presure to be very high and the muffler to have only a 4" to a 3" out let and the baffle in the muffler pluged up and the air cleaner had 12 in of vacuum. So I cut the outlet pipe out and installed a 5" outlet that the book calls for,to reduce the back pressure from 14 lbs to 2 lbs. Then I removed the air intake from in front of the left radiator and opened it up straight through the side to 6" x 18" with a vent cover. As Fred Hobe shows how to do this on his web site. This reduced the air intake vacuum from 12" to 3". Now I have full fuel rack at take off from a stop I get very little black smoke and it jumps off the start line. From the freeway ramp to the freeway I am getting on at 65 mph with 2/3 pedal left. And better fuel mpg. After 5000 miles I had Detroit do a HOT engine valve and injector lash tune up that the detroit book calls for. Also we cleaned out the over size radiators and replace the air cowles on both sides of each blower fan As Fred shows how to do this also. We ran to Sturges last year with 21 on board loaded and up to 9000 feet above sea level and had No power or over heat problems. It did use a half gallon oil because of the air box check valves. But no oil from the valve cover vent pipes. It ran at 190- 210 water temp and 25 to 75 oil lbs. with exhust temp 900 to 1200. We also installed a custom made ratchet shifter and did some adjustments on the 740 auto transmission ( shift kit) no sliding into any gear, Good solid shifts up and down. Rebuilt the rear end and the drive shaft. Also installed a double oil filter head for 2 oil filters. Also an over sized water pump and a Detriot Fuel Pro Filter Water Separator . "If I can't run with the big dogs I'll have to sit on the porch and scratch." All this work is worth it. Let that engine breathe. More fuel, more air, more compression, more cooling. Check out Fred's home page. 10/4 Steve |
john w. roan (Chessie4905)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 19, 2006 - 5:34 pm: | |
Most throttle delays are adjustable, so you could cut back the amount of delay till you get the proper smoke/ accel that you would like or tolerate. |