Prop Help !!!!!!!

[Dennis Avery]

I have a 1989 supra t6sm comp classic , And I am not sure what prop to run I have an 13x14 rh twist on it, not enought prop. thats what came with the boat and i am sure thats not the stock prop,
Also found out the prop shaft is bent, vibrates alot , took it out and its bent . where is a good place to get a new on or straighten the old one????

[jet]

14x14 with a flat cup or something close to that. Its been on my boat for a year now. And Im only using 5-10% of the throttle now.

[jasonwm]

Which engine is in the boat currently? How do you use the boat (percentage of time spent wakeboarding, wakesurfing, skiing, tubing, etc.)? Are you running additional ballast? What altitude do you typically boat at?

Let me know and I can give you a recommendation.

[beast 496]

14x14 with a flat cup or something close to that. Its been on my boat for a year now. And Im only using 5-10% of the throttle now.

Please explaine the 5 to 10% throttle?????????? I routienly run 100% wot many times, just to do it. WOT = 52 mph @ 5,250 rpm. At 10 % throttle we are just holding a very slow plane. I am just wondering the explanation. Al

[Ptownkid]

I imagine he means he spends the majority of his time riding not racing...

[docdrs]

14x14 with a flat cup or something close to that. Its been on my boat for a year now. And Im only using 5-10% of the throttle now.

This really means nothing, what tranny do you have? You have to be more specific. Cup means alot and is not measured by flat,medium ,steep. It has a value in thousands of an inch but can be characterized by long or short. 5 -10% of throttle would mean like 3-6 mph wtf is that?.....are you pwi?

[docdrs]

I have a 1989 supra t6sm comp classic , And I am not sure what prop to run I have an 13x14 rh twist on it, not enought prop. thats what came with the boat and i am sure thats not the stock prop,
Also found out the prop shaft is bent, vibrates alot , took it out and its bent . where is a good place to get a new on or straighten the old one????

Ok what do you want? more mph? more hole shot? what is your wot rpm with current prop? what are your engine wot ratings? are you using ballast? how much? do you want it for surfing, cruising, wakeboarding, wakesurfing, or slalom?

[beast 496]

I am fairly sure the PCM engines in all supras were LH rotation. The versions in Nautiques were RH. Thus the prop should also be a LH rotation. As per size and pitch a 13 X 14 sounds correct. I have a few early Comps in storage and all have the same prop, but are LH. If you have the PCM tranny which is a slight gear reduction tranny it may be differant, but with the Borge Warner 1 to 1 I believe 13 X14 sounds correct, WOT should be at 4,400 to 4,500 on the OEM 351 PCM Ford. Good luck Al

[jasonwm]

A 14" pitch prop on an inboard without gear reduction and with a ~250HP engine sounds incredibly underwhelming to me. I would be looking for something closer to 11.5" or 12", like ACME's 525 or OJ's 334.

[wotan2525]

You want my advice? Talk to ACME or OJ. They have the experience and the expertise to recommend you the perfect prop based on your riding style and needs. If you were going to buy a new cam you'd probably talk to Crane or Comp, right?

If you're not interested in a new prop -- a local prop shop can always re-pitch your current prop and make it better suited for what you need.

[jet]

What I ment by that is with the old 3-blade I was at 90% throttle and it would take 3-football feilds to plain out and get to the correct speed 17-20 mph..and then it couldnt hold the speed. Now..Im only using 5-10% throttle (estimating) and I do have a RH and 1:1 tranny. There is a reason I was asking about the tranny..because acme is sending my buddy 2-props to try out and it was all about what tranny he had, so I was trying to get another opinion. WOT..why?? lol. I know your a skier. Because of my old 3-blade I disconnected my back-2 barrels on the carb..so it wouldnt try and engage while saced out and my boat hasnt seen 30 mph in 5-7 years..I just baby her.

[beast 496]

No worry's Jet. Ya I do like to run WOT alot, or at least around 40 mph+. Heck I pull my son and his friends tubing at around 45 mph. I have not really tried wake boarding, but maybe this summer. Al

[docdrs]

At wot you want your engine to be with in its spec'd parameters as far as rpm's.
If you don't get there ,then you are over propped and if you exceed the recommended max rpm's then you are under propped. Thus either putting more strain on the engine or over reving with chance of failure respectively.

[Hagman]

My experience with props . 86 Comp 13x13 cup,1 to1 trans, sea level
I sold My first boat a 1978 uro style skie boat with a 115hp merk on it ,to a friend . It was a sweet out fit that would do 50+ depending on how for I wanted to push my chest out . I would get annoyed when my buddy with my old boat could scream by any time he wanted. So I asked the dealer about changing props to get more speed. He told my the comp is not made to go fast it’s made to pull skiers. I thought that’s BS I’ll have my spare prop repitched to a 13x14 that should give a little more top end. It didn’t help. The boat was a slug out of the hole , I lost RPM= power at skiing speed and at about 43mph the boat wanted to stick it’s nose it the water. I put the 13x13 back on , years later I loaned the 13x14 to friend he dinged up when he got it fix we went back to13x13. I came across a 13x12 . It was a real stump puller. The boat still put it’s nose in the water at 43 but the motor was turning about 5 grand that’s not good I went back to the stock 13x13. About 5 years ago I put a 13x12.5 4 blade on . What a sweet prop it turns the same rpm as the 13x13 3 blade , same top end ,better out of the hole best of all runs smoother. If your looking to make a change I agree with Wotan 2525 talk to the guys at Acme or OJ save some money and get the rite prop the first time.
The only way I’ve ever gotten more speed is by raising the cavitation plate up a full tank of fuel and 3 ladies setting in the back set. Ps If your are going to spend any $ on speed parts it won’t help much leave the cam stock spend your $ on a good balance job.
That’s just my experience.

[beast 496]

Dennis and Jet, are you running the PCM transmission? Or a Velvet drive? Al

[beast 496]

Hagerman, You are very correct as per speed, another item, is we are dealing with inboard flat bottom hulls made for tracking straight. I can tell my hull is running efficiantly up to about 42 mph. Over 42 and we are starting to plow or bow steer, The aft is being pushed up and bow down. at speeds above 50, which these hulls are not designed for, the bow steer is magnified. We use our boat for barefooting, slalom, and knee boarding. As well as the usuall tubing and such. Haven't made the leap to wake boarding. Al

[jet]

Im not sure on that one..I always heard them called velvet drives, but I think my tranny tag says PCM??

[sybrmike]

Like Beast said, these hulls are top end limited by design. All the old tournament style inboards have a slight hook in the bottom of the hull at the rear - almost imperceivable unless you run a long straight edge. This hook forces the stern up and bow down to help it track straight through a course with minimal wake. All that extra wetted surface is great for slalom, but not top speed or throwing a big wake.

I think Tige was one of the first to eliminate the hook (TAPS) to allow the arse end to sink down for more of a wake making machine. It's all a compromise - great ski boats generally don't make great wake boats & vice versa (just as stump pulling props sacrifice top end speed). You can shift the curve with prop selection, but performance will still be limited by the overall design of the boat.