Prop Ideas
 

I just did fresh builds on a Saber 28. Running standard length Bravo Drives with 1.5 XR Gears. Boat has twins. Old build were 465 HP each on the dyno running 88 GPS with 30 Bravo One's 5400 RPM I bought it with them so I don't know if they were ever worked.

Everything else is the same with drives, etc. new motors are 640 HP each at 5300. Probably stay with Bravo 4 blade props I am also running Drive Guardians this year. Thoughts of where to start?

I would start where you left off. Get solid data with your old/existing props and the new motors. Yes I understand you 'may' be underpropped considering the HP upgrade, but at least you have a base line. Once that is done you will have a more refined starting point on which direction to go.

If I was spinning the 30's at 5400 before I can only guess that it will be way underpropped. I don't know if there is a calculator that suggest increases by HP or something.

I'm curious did you increase the size of your engines, or add blowers? An extra 200 hp is a big gain. Whenever I increase power but kept the engines the same size, I used the same props. I always hoped to spin a larger prop, but that was never the case. Again, with me, I was making more with the same size engine, which needed to be spun harder to make the increase in power. If you added a blower to your engines, that is something I have no experience with.

Please let us know what you did. I think that would help in the prop recommendation.

They are/were Hawk 525SC's basically a 420 with a 174 Blower we went full roller and aluminum heads and slightly increased the boost to about 6 1/2 lbs.
The builds were done by Tyler Crockett, they pulled 640 HP at 5300 RPM on 89 octane.
The original builds pulled 465 HP on the dyno built by More Power I bought the boat with those motors.

Working numbers, 200 hp would probably translate into a 1000 rpm gain if you kept the same props.
I would probably try some some 36 Bravos. You may want to consider a gear change to 1.35's for more prop options.

Thanks Griff, we did these builds based very much to your suggestions. We are very pleased and had results similar to what you suggested they be. Unfortunately we went to 1.5 last year with XR gears. I was hoping to get more time out of the previous build. I won't say it was bad just not with many components and quality of parts that I would normally put in a build. These should give us many years just killed the pocket book,

Were the engines both Dyno'd at Tyler Crocketts shop? I know that Dicks dyno numbers are very conservative, so unless the engines were both dyne'd at the same place, I wouldn't put much stock in the hp comparison. . Getrdunn is very familiar with More Power, shoot him a PM, he will confirm the their numbers are always WAY low. A 525SC certainly makes more than 465 hp stock, what exactly did Tyler do? Was it just a head swap and an increase in PSI? Also was Dicks number using all accessories and stock exhaust? Something really seems off on the comparison of the two engines.

We did not dyno the stock engines at Tyler's one of the motors was not running, he is also pretty conservative as well keeping it real as far as numbers, he has tuned some other builds for me that I though would make more. The only parts that we used from the original build were the blocks and cranks, the blower we changed pulleys. Merc calls a 525Sc at 490 HP. The hawks are higher compression pistons, smaller blower and carb. They ran strong for what they were,

The best thing to do, is just buy some different props and see where it puts you. Every Inch of pitch will reduce your RPMs 200. If you gain 1000 RPMs as Griff said, there isn't a Bravo prop steep enough, so you may need to re-gear your drive. However, I would test out some steeper props first. Have you called Airmarine in Chicago, to see if they have set of 34-36 B1s you can try? Their test program is way cheaper than BBlades, and you don't have to ship anything. However with the lockdown, they may not be open.

I have not talked to Cathy yet. With all that is going on I'm probably a month from being ready anyway. That is the plan though.

I had a long written post, then I re-read that they were dyno'd at Dicks. That dyno is a little stingy. At this point were are just dyno racing. I know that the boat has always ran 88 mph with the Hawk 525's (I believe they are closer to 540 hp) The best advice as already stated is to start where you left off. I think you'll only see a 300-400 RPM difference and then work the props from there.

Even if that is true based on where they make power now 5300 will take them to at least a high end 32 to probably a 34

The dyno sheets from More Power were part of the file when I bought the boat, you wouldn't think you would want conservative numbers in that scenario. Just my $.02

Keep in mind that 34 Bravo's perform somewhat differently that other Bravo pitches of Bravo props. BBlades had posted the specifics in older threads. That is not saying they would not work fine on your boat though.
First thing I would do is run your props and then see what you can find to borrow in the 32-36 range locally for testing. Maybe even look for 30-32 5 blades to try. Then use BBlades test program if needed.

I'm only assuming because of more surface area in the water that a 5 blade will put more stress on the drives. Thoughts?

yes it will, do you know what the boat weighs fully dressed ?

6200 so I'm told.

Yes, but most of the stress is from re entry after leaving the water. You boat is not heavy at all, so it should be fine.

I'm also installing Drive Guardians

I have a set of Mercury labbed 34's cut to 33's I picked up last year but haven't tried them on my boat, may be to much for you

I'll keep them in mind. I do have some test units available. Once figured out if its a fit we can talk.

Now that I am on the water I'm surprised even with adding the additional HP that I probably will only jump 1 prop size or simply massage mine with more cup. I boat on the chain in Northern Illinois and they are short lakes. Most are a drag race so to speak, so quick is better than top end (just not enough room) Picked up about 5 MPH at similar RPM which really doesn't make sense unless it was slippage or am slipping trying to catch up now. The mid range is unreal!

Wouldn't be able to spin those without shorties. Baseline with stock 32s is 5300 RPM we would like 5400 to 5500. A little tweaking and should be there.