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  1. #21
    ptscon's Avatar
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    Use the highest octane you can get and send it.

    Maybe don't spin it super high, say under 8600 to keep boost down a little.

  2. #22
    suck my wake's Avatar
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    Quote Originally Posted by Smashrockwell View Post
    DO you recall how much you had to advance or retard timing with this set up?
    There was no playing with the timing at that time, the tune was the Riva ecu and that's it. Couldn't make adjustments like you can nowadays, not unless you had a motec

  3. #23
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    Quote Originally Posted by tiderider View Post
    I don't think your set up is anywhere near his with your cam upgrade. This makes it even more difficult to tune with a stock siemens ecu besides the 9.5:1 pistons. Riva Racing ECU contains that information, but no cam was upgraded on his set up, different story.
    I did have the Rotax cam in mine as well. There was just no adjustment capabilities with the ecu's back then. The only thing you could play with was fuel pressure and if you had one of those little black boxes you could adjust the injector pulses also but you couldn't mess with timing without a motec system. The Rotax racing ecu's hadore timing than the Riva ones I was told


  4. #24
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    Quote Originally Posted by rtarford View Post
    why don't you answer his questions?
    Cause your an idiot..

  5. #25
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    Quote Originally Posted by Smashrockwell View Post
    You're right. Well I can't see myself buying a Motec or another ecu for a 2003 GTX. Since I have another crankcase, a new set of 125mm 8:4:1 Cp pistons, and my old rods, I think it would be cheaper to run this engine and risk blowing it up than to buy a motec. I could get an entire new engine for less than $2900.

    Let's say I blow this engine up. I'll rebuild it with 8:4:1s, then I can just run a riva tune on my siemens ecu with the maptunerX? In this case timing would not be a big issue because I simply have a stage 4 with a cam. If I go this route, and the engine blows, I'm looking at $400 for a engine bore + replacing whichever components got taken out by the detonation.

    The other option is spending $2900 on a Motec? Hell naw.

    So this is my logic:

    I am going to start the engine running the Riva tune that is closest to my set up. I will use 100 octane. I was considering a data logger but why'd I need that if it won't read, and I cant adjust timing on a siemens ecu? I have an afr gauge that I will watch for fuel and I will let the knock sensor do its job on timing if it detects knock. Seems idiotic but to me a Motec on this hull is more foolish and costly than a complete rebuild.

    Lets say I fire it up, and the timing is way off. What will happen? It will knock and the knock sensor will signal the ecu to retard/advance timing, right? It will retard timing until it doesn't detect knock then it will advance a bit and set timing there, correct? If I run it at low rpm what is the real danger? Will I be able to see knock sensor info with a maptunerX (not unless I get a data logger, smh)?

    And I appreciate the knowledge but I wonder how much of this is just spookism? Who has actually blown up an engine running 9:5:1 pistons on a sea-doo? Specifically because of detonation.

    Since I'm going crash test dummy with it, any recommendation to put me in the safe zone would be appreciated.
    You will not be able to run that set up with the siemens ECU.. BOOM!

  6. #26
    ptscon's Avatar
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    Quote Originally Posted by tiderider View Post
    You will not be able to run that set up with the siemens ECU.. BOOM!

    Why? All he needs is enough octane to keep it from knocking. 92 is probably fine for cruising and general rides but if he wants to push it to the max he will have to add octane by mixing in some race gas or sourcing slightly higher octane gasoline.

  7. #27
    tiderider's Avatar
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    It will run like shit and defeats the purpose of getting everything out of the engine from the parts he put in to it..... A stock 215hp engine with 8.4:1 pistons will run better.. Change your spark plugs every few hours with that high octane if you can get a few hours out of it.. At WOT? .. And Again.. BOOM...!

  8. #28

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    Quote Originally Posted by tiderider View Post
    Cause your an idiot..
    holy ****, did we just meet up with Sherman and Mr Peabody and get into the wayback machine and went to elementary school ? I guess the only response to that is , sticks and stones may break my bones but names will never hurt me or I am rubber and you are glue everything you say bounces off me and sticks on you

  9. #29
    ptscon's Avatar
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    Quote Originally Posted by tiderider View Post
    It will run like shit and defeats the purpose of getting everything out of the engine from the parts he put in to it..... A stock 215hp engine with 8.4:1 pistons will run better.. Change your spark plugs every few hours with that high octane if you can get a few hours out of it.. At WOT? .. And Again.. BOOM...!
    You keep saying "boom" but don't explain anything, if you haven't noticed this is a performance forum.

    Yes he can adjust timing with the Siemens ecu. All he has to do is ask Jesus for a safe map for whatever octane is available to him. He's not the first person running those pistons with that ECU.

  10. #30
    Quote Originally Posted by tiderider View Post
    It will run like shit and defeats the purpose of getting everything out of the engine from the parts he put in to it..... A stock 215hp engine with 8.4:1 pistons will run better.. Change your spark plugs every few hours with that high octane if you can get a few hours out of it.. At WOT? .. And Again.. BOOM...!
    I appreciate your concern but your claims seem to be rhetorical. You claim "You will not be able to run that set up on a siemens ECU". Please explain why? I'll explain why I think I can.

    If you go to the maptunerX library and compare my mods, you will see I have a STAGE 3 215 - 255 9200 80DK or better. This stage 3 tune is ran on a Siemens ECU. Mods I have the Stage 3 doesn't are a racing cam and 9:5:1 pistons, VT1100 and a RRFPR. Considering 9:5:1 pistons will raise my compression I understand your concerns about timing and detonation. If we are considering this we also must consider this Stage 3 tune was designed for 18lbs boost max. I will be running 15lbs boost max. So why would you conclude having 9:5:1 pistons and a racing cam on a Stage 3 wont allow me to run on Siemens ECU? If this stage 3 tune has a timing base map tuned for 18lbs of boost on 8:4:1 it should be able to handle 15lb of boost on 9:5:1s. 8:5:1 with 18 pounds of boost is 18:9:1 compression. 9:5:1 with 14lbs of 18:5:1. This means the 9:5:1 pistons with 14 lbs boost is less cylinder compression that the 8:5:1 18 lbs boost tune is build for. Now if we consider the Siemen ECU knock sensor will work with this tunes ignition timing base map, what do I really have to fear? I just provided evidence that the cylinder compression is within the tune and that this can be done on a siemens ecu.

    Secondly, I found a thread where Vtech was working on timing adjustments on the Siemens ECU. Its called Edit Ignition maps Siemens ECU. In this 2014 post they site my ECU part #
    664947. I don't know if this project was discontinued but there seems to be evidence against your claims that timing can't be adjusted on a Siemens ECU. Even if it can't, I want to see how you falsify my claims about my compression being within spec to run a Stage 3 tune. Seems I can run it with a Siemens ECU.

    Lastly, Suck MY Wave ran similar mods with a Riva racing ECU and a Rotax Racing Cam. I cant find a Riva Racing ECU anywhere but why would we presume that engine control unit would have a tune their current engine control unit management system (maptunerX) doesn't? You think the tune from the Riva Racing ECU aint in the map tuner?

    Regardless, after further research the 9:5:1 pistons don't seem to be as big an issue as some make it.




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