Comfy cruising RPM on a SBC

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RYPiii
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Comfy cruising RPM on a SBC

Post by RYPiii »

What is a comfy cruising RPM for a 327 SBC and speed? At 3500 I’m cruising 26-27 and it feels good. Being told that’s too high RPM for cruising.

Striker543
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Re: Comfy cruising RPM on a SBC

Post by Striker543 »

Mine cruises between 3200-3600 depending on conditions with max rpms at 5200. Not much you can do to lower cruise rpms other than adding more pitch, which will also reduce your overall rpms.

RYPiii
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Re: Comfy cruising RPM on a SBC

Post by RYPiii »

Thank you. I'm between 3500-400 comfy. may add some pitch to see how she responds.

One Eyed Gator
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Re: Comfy cruising RPM on a SBC

Post by One Eyed Gator »

Just to ask what is the gear ratio you're running what prop and length and what is your current WOT?

RYPiii
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Re: Comfy cruising RPM on a SBC

Post by RYPiii »

One Eyed Gator wrote:
Wed Sep 23, 2020 3:28 pm
Just to ask what is the gear ratio you're running what prop and length and what is your current WOT?
Precision gear box 1.9:1 with 76” water walker. Only ran the boat twice since I bought it. So I’m not sure about the WOT. I’ve had it up to 5000 rpm and it had some left. Didn’t check the speed.

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Re: Comfy cruising RPM on a SBC

Post by Striker543 »

For what it’s worth when I bought my boat it had a 2.38 Gear and 3 blade 78” NGH. With that setup it cruiser closer to 4000 rpms. I changed it to a 2.68, added one blade to the prop and turned it into a 4 blade 80”. That made a big difference in overall push and also brought my cruise rpms down.

One Eyed Gator
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Re: Comfy cruising RPM on a SBC

Post by One Eyed Gator »

The Falcon I believe max out at 2450. With a 1.9 at 5,000 engine rpm your turning the blades 2632 rpm.

4,700 with a 1.9 ration put you at 2474.

You said you still you still had pedal left at 5,000 so you're turn those blades over there max.

I would see determine my WOT rpm. Then make your prop with a sharpie, take your tools to repritch the prop. Add a little pitch at a time and see how it feels. I look for the sweet spot for my riding style.

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RYPiii
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Re: Comfy cruising RPM on a SBC

Post by RYPiii »

One Eyed Gator wrote:
Thu Sep 24, 2020 3:18 pm
The Falcon I believe max out at 2450. With a 1.9 at 5,000 engine rpm your turning the blades 2632 rpm.

4,700 with a 1.9 ration put you at 2474.

You said you still you still had pedal left at 5,000 so you're turn those blades over there max.

I would see determine my WOT rpm. Then make your prop with a sharpie, take your tools to repritch the prop. Add a little pitch at a time and see how it feels. I look for the sweet spot for my riding style.


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Tried calling you bud.
While sitting on wet hard ground, I stuck it. Surprising. I thought for sure an aluminum boat with a gear box and big prop would go anywhere. I guess the 327 is under powered for the weight of the boat. While stuck, I had it pegged and it wouldn’t pass 4700 RPM. I don’t think adding pitch will help any. If anything, maybe take pitch out???? Curious what the experts have to say

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kwanjangnihm
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Re: Comfy cruising RPM on a SBC

Post by kwanjangnihm »

Is your 327 stock and is this a 2 blade falcon? Where is the pitch mark set at now?
He'll cut your throat, baby, stick you in the back, drive off in your Cadillac.
He's more trouble than you think, he'll kill your sugar, leave you in the drink.

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OneBFC
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Re: Comfy cruising RPM on a SBC

Post by OneBFC »

Curious what the experts have to say
Easy, not enough power at 4700 rpm. That could be under 300hp pretty easily based on exact build.
-Russ
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NorthWestFloridaBoy
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Re: Comfy cruising RPM on a SBC

Post by NorthWestFloridaBoy »

On my old gilileo 1600-1800 rpm. That's direct drive though, probably not data your looking for though.

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