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sgt1970-442

hurth trans

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sgt1970-442

does anyone know the rpm limits on these?

i've done some mods to the motor and know its capable

6000rpm.

just wondering how far is safe to push the trans and acme 515 prop.

original rpm range 4400-4800

1999 indmar 350 vortec motor

carb 310hp

thanks steve

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Ndawg12
does anyone know the rpm limits on these?

i've done some mods to the motor and know its capable

6000rpm.

just wondering how far is safe to push the trans and acme 515 prop.

original rpm range 4400-4800

1999 indmar 350 vortec motor

carb 310hp

thanks steve

When the tranny blows up or you shoot a prop blade through the hull then subtract 1 rpm :)

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Bobby Light
does anyone know the rpm limits on these?

i've done some mods to the motor and know its capable

6000rpm.

just wondering how far is safe to push the trans and acme 515 prop.

original rpm range 4400-4800

1999 indmar 350 vortec motor

carb 310hp

thanks steve

When the tranny blows up or you shoot a prop blade through the hull then subtract 1 rpm :)

^^My vote for most useless post of the month Notworthy.gif

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Sixball

I would think you can push it as hard as your engine will go and still only see may be one or two MPH. the haul on these boats are the limiting factor. If you don't get the haul of a boat out of the water she just is not going to go fast. Give it some thought all our boats are pushing 300 + HP and were all going 48 / 55 MPH.

I would think the only benefit is you will get to know your Gas station very well.

I have no clue what the trans is limited to but another factor my be the Damper plate? Dontknow.gif

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Ndawg12
does anyone know the rpm limits on these?

i've done some mods to the motor and know its capable

6000rpm.

just wondering how far is safe to push the trans and acme 515 prop.

original rpm range 4400-4800

1999 indmar 350 vortec motor

carb 310hp

thanks steve

When the tranny blows up or you shoot a prop blade through the hull then subtract 1 rpm :)

^^My vote for most useless post of the month Notworthy.gif

Hey someone had to reply, maybe useless but hopefully he got a laugh out of it and a bump!!!

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Bobby Light
does anyone know the rpm limits on these?

i've done some mods to the motor and know its capable

6000rpm.

just wondering how far is safe to push the trans and acme 515 prop.

original rpm range 4400-4800

1999 indmar 350 vortec motor

carb 310hp

thanks steve

When the tranny blows up or you shoot a prop blade through the hull then subtract 1 rpm :)

^^My vote for most useless post of the month Notworthy.gif

Hey someone had to reply, maybe useless but hopefully he got a laugh out of it and a bump!!!

I did if that counts.

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winddawg

I think it is 5500 rpm max and that is dependent on duty and HP. You can find out more info on your transmission

HERE

If you are closing in on 6000 rpm it may be time to try a different prop.

-Dave

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sgt1970-442
I think it is 5500 rpm max and that is dependent on duty and HP. You can find out more info on your transmission

HERE

If you are closing in on 6000 rpm it may be time to try a different prop.

-Dave

dave,

the mods done to the motor netted about 30-40 extra ponies. thats according to the desk top dyno program i have.

i didn't go over board on hp or torque upgrades, just freed up some friction issues and opened up the exhaust.

changed the cam and lifters to a better hydraulic roller and roller rockers. patriot aluminum cylinder heads,

etx manifolds and locked the timing advance at 37*

this sunsetter is mostly used for skiing so the duty or use won't change.

thanks for the link to hurth and i guess i better get on the phone with bill at acme and see what he says.

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Soon2BV

What mods did you make will allow a higher max RPM?

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Needles

After adding torque and horsepower to a boat correct prop and final drive gear ratio must be matched to the horsepowwer and torque curves vs. optimum rpm to achieve any measurable results. Propeller efficiency with typical ski boat props declines rapidly as RPM increases past a certain theshold. ACME is very good at predicting this calling them should be a must. If increased top speed was the goal of the engine mods then I agree with the earlier poster that this will be limited by hull dynamics. My experience with these hulls is they will never "release" for any significant speed gains. Good luck and let us know how it turns out

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Woodski

As a reference, adding roughly 100 hp upped the speed from 45 to 56 mph and some of that probably was prop.

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sgt1970-442

ok to let everyone know, the mods that were done to this 99 malibu sunsetter lxi with a sv23 diamond hull were for losing weight in the center of the boat.

this has turned in to a mild build and nothing more. only thing i can say is with the mods that have been done i know the motor will turn 6000rpm easily.

i was just looking to get some feedback on trans and prop rpm limits.

this was not done for top speed, totally happy with 48mph

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Soon2BV

The reason i ask is because the engine is full of rotating parts that were designed for 5000 rpm.

Running beyond that increases the risk that one of them will fail.

Could be a bearing or a shaft or a seal or a roller chain or a ???? and it could be ugly.

6000 rpm is 20% above the design limit.

Making mods that will let the engine run faster does not mean it should run faster.

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sgt1970-442

The reason i ask is because the engine is full of rotating parts that were designed for 5000 rpm.

Running beyond that increases the risk that one of them will fail.

Could be a bearing or a shaft or a seal or a roller chain or a ???? and it could be ugly.

6000 rpm is 20% above the design limit.

Making mods that will let the engine run faster does not mean it should run faster.

i guess you missed 48mph is fine with me.

this was not done to go faster.

rpm limits on my engine were set at 4400-4800 and that was do to the cam limits and valve spring heights for coil bind.

not because the bottom end couldn't handle it.

small block chevrolets in stock form have been twisting way about 5000rpms for years.

don't want to come off as an azz but,this isn't my first rodeo building and modifying motors.

i have a 51 ford anglia with a 650hp small block chevy that runs 10.00 class and a 1970 olds 442 that has a stroked 455 motor that is now 496.

just was curious if anyone knew the rpm limits on the hurth trans thats all.

think i've found my answer with the help of winddawg's link.

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sgt1970-442

ok guys and gals,

i talked to todd at acme yesterday and got the word that there props will be fine past 6000rpms.

todd also said the 515 prop should be just fine. he said it might need a little tweeking and they

would work with me on that.

also did some research on the trans and was assured that it can withstand 6000rpms also.

just thought some of the group would like to know what i found out.

i'll post results of in the water tests in the spring. i can say that we've run it and it does

rev quicker with all the roller parts.

just can't wait to get it in the water, is it spring yet???

Edited by sgt1970-442

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