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  1. #1

    155hp 4 tec with supercharger

    Has anyone run a 155na engine with standard pistons and put a supercharger on it?? How did it hold up, and how did u manage the extra fueling? Can anyone work out the estimated hp output of this combo using a standard 215hp supercharger and drive gear? engineermike i like to hear your thoughts on this.


  2. #2
    2Blue's BFF! dsolie's Avatar
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    take a 155 and ad a SC you are at 185, add the IC and you are at 215.. HP wise.. There are a lot of other things you have to change when you install a SC.

    SD had at one time a 155, 185 and 215 options on the skis

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    Sorry, but this is not correct at all.

    The compression ratio on the pistons in a 155hp NA 4tec motor is 10.5:1, and they are cast. The 185hp, 215hp, and 255hp motors on the other hand all use pistons with a much lower compression ratio of 8.5:1. The difference between them is that the 185hp piston is made of cast aluminium like the 155hp piston is. However the pistons from the 215, and 255 motors are made from forged aluminum. The reason the 185 motor makes less power than the 215 motor while using the same Supercharger, and pistons of the exact same size & compression ratio is because the 185hp motor uses a flywheel that drives the supercharger at a slower speed than the 215/255 motors. While adding a charge cooler will without a doubt increases power, the fact that that the supercharger on the 185hp motor is making less boost is the main reason for the power difference.

    Quote Originally Posted by dsolie View Post
    take a 155 and ad a SC you are at 185, add the IC and you are at 215.. HP wise.. There are a lot of other things you have to change when you install a SC.

    SD had at one time a 155, 185 and 215 options on the skis

  4. #4
    Quote Originally Posted by boostaholic View Post
    Sorry, but this is not correct at all.

    The compression ratio on the pistons in a 155hp NA 4tec motor is 10.5:1, and they are cast. The 185hp, 215hp, and 255hp motors on the other hand all use pistons with a much lower compression ratio of 8.5:1. The difference between them is that the 185hp piston is made of cast aluminium like the 155hp piston is. However the pistons from the 215, and 255 motors are made from forged aluminum. The reason the 185 motor makes less power than the 215 motor while using the same Supercharger, and pistons of the exact same size & compression ratio is because the 185hp motor uses a flywheel that drives the supercharger at a slower speed than the 215/255 motors. While adding a charge cooler will without a doubt increases power, the fact that that the supercharger on the 185hp motor is making less boost is the main reason for the power difference.
    I know the 155hp engines have a higher compression ratio and use a cast piston. But providing the pistons dont break and you give it enough fuel what hp do you think it will be good for with 7psi at 8100rpm??? Im guessing high 200,s?? What do u think about 10.5.1 compression ratio and 7 psi boost do u think the combustion temps will be to high??

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    Never say never KirkF350's Avatar
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    Quote Originally Posted by boostaholic View Post
    Sorry, but this is not correct at all.

    The compression ratio on the pistons in a 155hp NA 4tec motor is 10.5:1, and they are cast. The 185hp, 215hp, and 255hp motors on the other hand all use pistons with a much lower compression ratio of 8.5:1. The difference between them is that the 185hp piston is made of cast aluminium like the 155hp piston is. However the pistons from the 215, and 255 motors are made from forged aluminum. The reason the 185 motor makes less power than the 215 motor while using the same Supercharger, and pistons of the exact same size & compression ratio is because the 185hp motor uses a flywheel that drives the supercharger at a slower speed than the 215/255 motors. While adding a charge cooler will without a doubt increases power, the fact that that the supercharger on the 185hp motor is making less boost is the main reason for the power difference.
    Just trying to make sure I understand. If I have a 155hp or a 185hp engine and go to the 215 hp pistons and add the 215hp s/c, I will have a 215hp motor?
    Is there any remaping to the ecu or changing of injectors that will be needed too?
    I only ask because I am thinking conversion donor motors might be found cheaper and then upgraded for hp.

  6. #6
    King_Of_Fun's Avatar
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    You'll also need a different ECU to go from 7600 rpms to 8100 rpms. Jeremy had a post with well over 100 pages of his upgrade from 185-hp to close to 255-hp. He was lucky to get some used parts. But the 155-hp engine would need at least 185-hp pistons to lower the compression ratio, the rear pto cover to mount the SC on, and a 185-hp flywheel (with the 2 rows of teeth) to drive the SC. If the 155-hp ski has plastic pump, it will distort when the power is increased. I'm sure I missed a few things too... Ron

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    Quote Originally Posted by damo.r View Post
    I know the 155hp engines have a higher compression ratio and use a cast piston. But providing the pistons dont break and you give it enough fuel what hp do you think it will be good for with 7psi at 8100rpm??? Im guessing high 200,s?? What do u think about 10.5.1 compression ratio and 7 psi boost do u think the combustion temps will be to high??
    My current best guess is ~12-13hp per PSI of SC boost added, on a current 4tec motor. Also, I estimate an external intercooler be worth 10-15hp. So my guess is around 260+ hp running 10.5:1 w/ .5bar( 7PSI) boost. Although you would have MUCH better bottom end power, and slightly more torque throughout. It's not so much the combustion temp that you are fighting, it's detonation that comes with it. You are more prone to detonation the higher the static compression ratio you are running. Add to that as you mentioned, they higher combustion chamber temps, and you better have knock control, a good intercooler, and HIGH octane gas! The fudge factor for having it tuned to make good power without detonation issues becomes a MUCH finer line. Plus add to the fact that your using cast pistons. Cast pistons more brittle than forged, and can crack, or fracture under hard detonation. While forged pistons are more forgiving, and will tend to bend, or dent a little (at first anyway).

  8. #8
    If i knew,...I wouldn't ask sea-one's Avatar
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    could you run a colder plug and higher octane fuel to counter the detonation?

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    2Blue's BFF! dsolie's Avatar
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    Quote Originally Posted by boostaholic View Post
    Sorry, but this is not correct at all.
    I know there is a lot more technical stuff (that you have provided), I was just stating the base motors on how SD had a 155/185 & 215 with the main "bolt-on" components being the SC&IC.

    Maaaaybe I should have worded differently..

  10. #10

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    Talking about just the bare shortblock. The only difference between a 155/185/215 4tec motor is the pistons. Even the rings are all the same Thanks Seadoo!

    Regarding the rest of the motor, there are a number of parts that are different of course.

    Parts that are different between (155,185,215) 4tec motors:
    * PTO Cover (No SC hole on 155s, but can be drilled out, and added easily)
    * Flywheel (different for all engines)
    * ECU (different for all engines)
    * Fuel injectors (155- 32# 185-??# 215-38# 255-42#)
    * Fuel pressure regulator (155-42psi 215/255-58psi)
    * Intake manifold (different for all engines)
    * J-pipe (there are (3) different heat levels, each made from a diff. alloy)

    There may be a few things I'm forgetting, but as far as internal engine components the pistons are the only difference.



    Quote Originally Posted by KirkF350 View Post
    Just trying to make sure I understand. If I have a 155hp or a 185hp engine and go to the 215 hp pistons and add the 215hp s/c, I will have a 215hp motor?
    Is there any remaping to the ecu or changing of injectors that will be needed too?
    I only ask because I am thinking conversion donor motors might be found cheaper and then upgraded for hp.

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