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Thread: higher boost???

  1. #1
    gmnhra
    after having some minor repair work (dead coil)done i made a few runs today at elsinore.
    540cid w/carbed whipple blower...
    boats seems to run o.k...but on acceleration the boost gage goes up to 9 -10 lbs and reads 3-5 lbs at 3500 rpm...
    i am quite sure that before, the motor would only read boost (5psi)at above 4500 rpm....
    is there any mechanical explanation to this (other than bad gage)???? it did seem that the motor was down on power a little...???
    its always soemthing...

  2. #2
    502procharger
    i do not have a whipple but i do run a procharger, i use a gaffrig boost gauge and i too have noticed that sometimes it reads different under the same conditions and rpm. i never know if i am really getting more boost, or if my gauge is screwed up. i seem to be going about the same speed when it reads 5 lbs as 8lbs( that it reads every now and then) i do not know if this helps at all, but i thought i would share my experance. good luck

  3. #3
    HM
    Super chargers, especially compressor style (Whipple) and Roots style (the big blowers) make boost according to throttle and load and have less to do with rpm. Your whipple will make more boost on acceleration as there is more load especially if you give it more throttle then back out of it to cruise. Even if you don't back out of it, you can experience boost drop due to reduced load on the motor.
    Prochargers also have the same phenomenon, but not as great.
    More than likely there is nothing wrong with your gages.

  4. #4
    Hotcrusader76
    HolyMoly:
    Super chargers, especially compressor style (Whipple) and Roots style (the big blowers) make boost according to throttle and load and have less to do with rpm. Your whipple will make more boost on acceleration as there is more load especially if you give it more throttle then back out of it to cruise. Even if you don't back out of it, you can experience boost drop due to reduced load on the motor.
    Prochargers also have the same phenomenon, but not as great.
    More than likely there is nothing wrong with your gages.God I love my turbo!

  5. #5
    Lake_x
    I would check your valvtrain. Suspect a rocker arm or valve spring .........

  6. #6
    Senior Member
    Join Date
    Jun 2009
    Posts
    10,871
    One thing to consider (and yes I'm serious), is that Elsinore gets green and sticky. We used to run our ski race boat there all the time testing and it would consistantly run more boost at Elsinore and run slower because of the sticky water putting more load on the boat. Certain times of the year are worse than others too. Boost is definately affected by the load placed on the boat. This boat is turboed but the principle is the same. Boost is boost and load is load.

  7. #7
    gmnhra
    for those of you who diagnosed valve train...bingo...
    broken crane roller lifter on an exhaust...caused some back pressure and surely explains my drop in horsepower!!!
    kudos to GT Performance...thru no fault of theirs, the lifter breakage also took out the cam and required that the whole motor come apart...the repair was completed in less than a week and mostly on the warranty....Gary and his guys really take care of their customers....

  8. #8
    JLaughreySS24
    Hey Gmnhra, Do you think you could post some pics of your motor set up? I have a B&M 250 with superchiller and want to switch over to the Whipplecooler and blower. What size compressor did you go with? Thanks for the pics and help.

  9. #9
    HM
    JLaughreySS24:
    Hey Gmnhra, Do you think you could post some pics of your motor set up? I have a B&M 250 with superchiller and want to switch over to the Whipplecooler and blower. What size compressor did you go with? Thanks for the pics and help.My dad just switched from a 250 intercooled with dual 950's on his 502 to the new Whipple 3.3 liter, intercooler and injected. It has only been on the dyno so far and is making another 100HP++. The Whipple generates less heat and the intercooler is more effecient so they up the boost to 12 lbs and expect to continue to run on pump gas - they also reverse flow the water to go to the heads first(the magna flow pumps were great for reverse flow without the airpocket problems)
    The new 3.3 liter is about 50 ci smaller than the B&M 250, but is a ton more effecient - not to mention it fits under the hatch!

  10. #10
    JLaughreySS24
    Cool, Thanks for the input HolyMoly. I was wondering how close the 3.3 and the 250 were in ci size. I know the whipple is way more effecient and yes I was would like to sneak it under the hatch if possible. I want to go with the carb version and run only 5 or 6 pounds. Thats what im running now with the 250. I only have the bravo 1 and have had no problems but I do baby it. I was looking into billet marine's xr upgrade that they are doing on the bravo's so we will see. I was trying to get some pics from everyone with the carbed whipple so I can see how close its going to be fitting under the hatch. Thanks again.

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