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Thread: Crossflow build

  1. #16
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    1980 Johnson 140 in Kenora , comes with a boat
    https://www.kijiji.ca/v-powerboat-mo...ationFlag=true
    Build two, the StarCraft for shiit weather.

    But I'd redo the StarCraft and keep the 140 on it. Good boat.
    Last edited by FMP; 08-31-2019 at 09:16 AM.

  2. #17
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    140 looper and nic bore v6 merc within 20lbs

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  4. #18
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    Okay , the looper big bore sounds better

  5. #19
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    Quote Originally Posted by Forkin' Crazy View Post
    Find a 79 or newer 140 and build a drop on. Keep the 88 for a spare for when you blow it up.

    79 up has the same linkage. 78 down no.

    In 87 they started rating HP at the prop instead of the flywheel. So you really have a low compression 115 or 100. I think the 87 up 115s were the old 140 with looser heads.

    Some one will be along in a minute to tell me how wrong I am or agree with me, one or the other!!! LMAO!!!

    The heads in 79 and 80 will probably be good enough. Premium fuel ONLY!!! I am more of a V6 Xflow guy. But I assume they were like that because right after 80 on the V6s they started loosening the heads or adding thicker head gaskets because of the crappy gas. No one wanted to pay for premium.

    THIS 100% correct! They are all over the place for cheap. Hell I have had people give them to me. Got one on my G3 1860 duck boat.
    Last edited by perfmarine1; 08-31-2019 at 10:02 AM.

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  7. #20
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    I'll keep an eye out, to busy till Dec to work on it. Just want to have all my ducks in a row before I started tearing into it. I also found a blown xp 200 that weighs 380lbs. But that'd either rip the transom off or give a spectacular wipe out.

    I still like the idea of a light weight massaged v4. Relatively light package, getting on plane isn't an issue. Gonna aim for that first.

    Just a question, been looking at boat hp ratings. Seems like it's a calculation rather then actual strength capacity on smaller boats? Wondering if going over the boat spec plate will cause any issues other then just over powering the vessel.

  8. #21
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    Quote Originally Posted by powerabout View Post
    140 looper and nic bore v6 merc within 20lbs
    With a light single ram bass mid? W/O the trim pump, etc? Light cowl, flywheel too, etc? I bet I could trim some fat off a 140 looper! BTW, how much is a good nic block ready to assemble? And the damn ring$$$$$$$!!! Hey, I like the nic motors too. I have 3 of them so far.

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    Quote Originally Posted by Fastbass88 View Post
    I'll keep an eye out, to busy till Dec to work on it. Just want to have all my ducks in a row before I started tearing into it. I also found a blown xp 200 that weighs 380lbs. But that'd either rip the transom off or give a spectacular wipe out.

    I still like the idea of a light weight massaged v4. Relatively light package, getting on plane isn't an issue. Gonna aim for that first.

    Just a question, been looking at boat hp ratings. Seems like it's a calculation rather then actual strength capacity on smaller boats? Wondering if going over the boat spec plate will cause any issues other then just over powering the vessel.
    No such animal. Unless if that is shipping weight less gearcase.

    BIA rated HP is calculated by a formula. Ignore it unless you have to have full coverage insurance, or if your boat police are pricks up there? Why not run the 88 cowl. My bet is they are too lazy to get the model number to look it up.

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  11. #23
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    I was going off Nada guides for weight. Looked up the model and said 380lbs.

    Id be all for a lightweight exotic looper if funds permitted, but they don't.

    We do have some authority roaming around. That's why I thought I could crank up the 88 and use the same hood. Insurance doesn't care, let alone would know what to look for mechanically.

  12. #24
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    Quote Originally Posted by Forkin' Crazy View Post
    With a light single ram bass mid? W/O the trim pump, etc? Light cowl, flywheel too, etc? I bet I could trim some fat off a 140 looper! BTW, how much is a good nic block ready to assemble? And the damn ring$$$$$$$!!! Hey, I like the nic motors too. I have 3 of them so far.
    I prefer steel bores and if i had a HP merc i would fit steel sleeves.
    Yes you can take weight out of a looper, silencer and base has some weight.
    Cowl and trays could be carbon

    Sure you can make more horsepower with v4 or v6 looper but weight is weight
    You can have lots of fun with a v4 xflow on a light boat
    Last edited by powerabout; 08-31-2019 at 10:38 PM.

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    As powerabout has just said you can have a LOT of fun with a light boat and a v4.
    I have a 620lb Dateline Bikini (Sidewinder clone) She had an Johnson xflow V4 85 (300lbs) Click image for larger version. 

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    This would fly along the loch at 40+ knts was no rocket but was great fun. I Took the 85 of her and have built a 140 xflow ported and tuned still to go on to her.
    But in the short term i have 120hp looper on another Bikini but the weight is a killer. I know the 140 Xflow will be the same as the 85 was. The boat handle great but putting the 120 looper on the other boat was a big mistake.
    It flies along but no where near a nimble as the xflow. The weight is only like 80lbs but thats 10% of the boats weight.
    Just mind if you get a looper you will have all that extra to lug around.
    If you find a Xflow and want to tweak it there is tons of great folks on here who have done the same and wiull gladly help out.

    I love my Bikini

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    That's been my thoughts. The 88 sit pretty deep in the water as is, while running the anti cav plate is 1in above pad. That's with a 20in mid. Might add some exhaust relief holes after I test vented props, idling is hard with all the water pressure.

    So as is, can I throw everything from the 135 on the 88(exhaust,carbs mainly)? I know a 140 drop on or 140 exhaust would be ideal, will see if I find anything. I still want a strong lake setup not a full race motor ready to burn down.

    Would just need best bang for labor, I would widen the ports and match the 135 block. Port match everything. Not doing fingerporrs but does scalloping the pistons and intake be worth it? Will be putting new rings and honing at the least if everything checks out inside. Hoping the crank set will be in spec.

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    Had time to pull the intake covers off both 88 and 135. 88 defiantly has the smaller ports. Internals from what I could see look great, but I'm assuming some work has been done to the 88 since there were some markings on inside of intake cover and port housing.

    88
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    135
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    88 inside of port cover
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  16. #28
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    Did some more digging, found some numbers of several threads that correspond. V4 90hp ports IN 2.170 EX 1.805, 140hp IN 2.100 EX 1.76 (measured from top of cylinder). Barbaric measurements i know but are helpful. Found measurements from a v6 but thats a different animal. There seems to be no porting templates in existence so looks like im stuck using stock heights. Also debating minor scalloping on the block/piston. Is it worth the hassle? It will be disassembled so thats the time to do it. Ill be cleaning up all the casting imperfections as well.

    I picked up a decent raked and vented 13.25 x 23p that i want to try and get a baseline from the current setup. I think all said and done hitting 60+mph with a rig that will be 1200lbs leaving the dock sounds attainable.

    Another note, everyone harps about crossflow harmonics at around 6200-6500rpm. While i aim for 6000rpm, some people say that only the v6's are affected by this?

  17. #29
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    Quote Originally Posted by Fastbass88 View Post
    Did some more digging, found some numbers of several threads that correspond. V4 90hp ports IN 2.170 EX 1.805, 140hp IN 2.100 EX 1.76 (measured from top of cylinder). Barbaric measurements i know but are helpful. Found measurements from a v6 but thats a different animal. There seems to be no porting templates in existence so looks like im stuck using stock heights. Also debating minor scalloping on the block/piston. Is it worth the hassle? It will be disassembled so thats the time to do it. Ill be cleaning up all the casting imperfections as well.

    I picked up a decent raked and vented 13.25 x 23p that i want to try and get a baseline from the current setup. I think all said and done hitting 60+mph with a rig that will be 1200lbs leaving the dock sounds attainable.

    Another note, everyone harps about crossflow harmonics at around 6200-6500rpm. While i aim for 6000rpm, some people say that only the v6's are affected by this?
    no problem with a v4 harmonics its even fire
    yes v6 xflow has an issue around 6200-6400 or something

  18. #30
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    Fastbass88 don't raise the porting any higher unless you are putting it on a boat that weighs less than 400 pounds. If you are going to scallop the Pistons don't raise the skirts over .375". I don't remember what my crossflow race engine weighs but I know for sure what my race v4 looper weighs because I weighed it recently. The complete v4 looper flywheel but to prop nut is 295lbs. The loop charged engine has the capability of making much more power. The crossflow does weigh less the parts are cheaper usually and they are much easier to port. If you plan on using those 135 heads you should at least run AV gas. My crossflow race heads are tighter than that, but they require 112 or methanol. Don't thin the bridges between the ports unless you won't to decrease ring life. If you decide to "D" shape the ports leave at least an 1/8" radius in the corners of the ports. I hope this helps. Find some 1 3/8" carbs. I gave Chris Carson the template to cut reeds for the crossflow reed block. This allows for better reed block flow and still use the reed block stuffers. This helps keep the bottom end and it helps with flow in the higher rpm range.

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