PQ290Enticer

I'm hoping that I will need bigger props this season so was looking around and found these two things as "options".
1st question: If my exhaust doesn't go through the hub at all do I need the vent holes? I am thinking these help the engine get some rpm on take off? Exhaust creates air bubbles around the prop?
2nd question: How does the exhaust tube length affect the prop or handling of the boat? Costs more if you shorten.
FYI, I am looking at Bravo-1 props with a 26" pitch.
Thanks for your comments and help.

Knot 4 Me

No, you don't need props with vent holes. If you had props with them you'd just run the plugs in them.

Not sure what you mean by exhaust tube length. Either you run an exhaust bellows or an exhaust tube. All big block boats should run a tube or if you have any engine with Corsa or similar exhaust. Doesn't affect prop or handling either way. I think Merc even wants a tube on their 383 reman's even if you don't have external exhaust (had a buddy just install a new Merc 383 and it came with a tube to install).

Smitty275

The length of the "tube" has a lot to do with how much stern lift you get from the props. Shorter tubes promote bow lift. Longer tubes and tubes with a flare on the end promote stern lift. Where the cup is placed on the blade can also affect bow or stern lift.

SB

iTrader: (1)

Yup, and some boats won't plane with the flare cut off the tube. More single engine boats than multiple...but...There is a trick to that though, if it happens. LOL.

Prop loaner program , or buddy with a garage/shed full of props , can really help things !

PQ290Enticer

I can't find much pertaining to modifying or enhancing the 290. I suppose that everyone else heeded the advice: "Don't bother". I'm still plugging along with a bunch of modifications and enjoying every minute. Maybe my experience will help someone down the road?
Anyway, with the info from Smitty, I am wondering, does removing the flare and/or shortening the tube work well for straight bottom boats or stepped or is it for any boat that could benefit from bow lift? I "feel" that my boat could use more bow lift but that may make things worse and yes I'm talking about chine walk.....again. What is the downside to having too much bow lift? Can you have too much bow lift?
SB, I do have a few resources for props and will hopefully be able to nail this down. Just looking for direction and what I can expect when trying different props. Currently thinking I will be using Bravo 1 props but only because I really don't know what other props work well with what I think is a heavy straight bottom 29' boat with twin big blocks with what is probably a low "X dimension".
I have looked at BBlades but is that just their version of the Bravo 1? No disrespect intended. Just wondering.
Thanks again for your help and comments.

Smitty275

My boats not heavy at all compared to the majority on this site. 22'6" and roughly 3500# when I go out solo to blow off steam. It needs a little bow lift. So just for experimental purposes I removed the flair from my 24 Bravo. Didn't change much planing wise. But it killed top end. Couldn't get the boat up on top so it could break free. Seems the short barrel props are more aimed at outboards on light hulls like bass boats that aren't tail heavy like a stern drive with a BBC or Diesel.
I've borrowed a bunch of props and learned a lot. Surprisingly, a labbed 26 Tempest was the fastest by several mph at 4600rpm. BUT...it would fall off plane between 2500-3k. Economy wise it sucked too. Just not enough blade area to keep the boat up at slower speeds. Like you, knowing I'm doing mods this spring, I picked up a bone stock 26 Bravo. It put me at the bottom of my rpm range @ 4200rpm, and is just a mph shy of the labbed Tempest @ 4600. Once I get on the water this year I'll see where I'm at rpm wise with the 26 Bravo and have it labbed from there by Billy Eaves.

bajaman

Some people spend their entire boating season or even their lives on trying to find that "perfect" prop, chasing every little last mph or other performance improvement. One of my best friends is this way, he has a variety of props he uses for specific occasions. Doesn't hurt that he worked at a local marine dealership for many years, so he had access to things most of us don't, lol! In all my years of boating I have found that there is always a compromise one has to accept. For me, that has always been having a decent top-end prop that had a good hole shot, but also was able to maintain plane at lower rpms. I've been running a Revolution 4 and have been very pleased with it overall. Last year I picked up a Mirage Plus and intend to do some comparison testing this year...just for grins. My wife asked me why I got the new prop, what was I looking for...and I said "a little more top end would be nice, as long as the hole shot doesn't suffer too much".
My last boat I had a labbed Mirage that performed well, especially at the top end, but it would suffer when I had a really heavy load, i.e. a lot of people in the boat, and wasn't ideal for pulling skiers. But when I'd bought that boat, back in 1992, what was important to me was SPEED man, the more the better. There weren't too many 21' boats on the lake that ran 70 mph, and I really enjoyed that. Many years later, new wife, new life, no kids, too old and fat for skiing, so different parameters, lol!

Props are "black magic" to a certain degree, and finding that perfect one is a bit like finding a unicorn. PQ, what are YOUR main requirements or expecations?

PQ290Enticer

I would say that I spend a lot of time cruising at 3500 rpm and then short (less than 5 minutes) WOT runs and I don't see that changing for me. From what I am reading, I'm sure I will be happy with a standard Bravo 1 prop or equivalent. My boat sits on a lift so changing props for "a special occasion" is a real PIA and not something I'm going to do. I want to "set it and forget it" which is why I'm going to take a chance and start the season going up 2" in prop pitch because I'm confident (hoping possibly dreaming) that by adding a total of 400hp this year I will be able to pull at least a 26" pitch prop. I usually have a full tank of gas (130 gal) and almost always go out alone however the grandkids are looking forward to riding on grandpa's boat so maybe more company this year and more 3500 rpm cruising.
Was there any thoughts on BBlades 4 - blade stuff? Are they a copy of the Bravo 1 or do they have better "black magic"?
Again, tough for me because unlike many on this site, (Cigarette, Baja, Sunsation) there's no one with my boat and setup to ask. I will put the effort in to check out a few different props but like anyone else, I don't want to waste time with a prop that doesn't work on a boat like mine meaning heavy 29' twin big block with a low X dimension.
Thanks again for the help, guidance and comments.

Knot 4 Me

Didn't read your post close enough and mistook exhaust tube of the prop for an exhaust tube vs exhaust bellows. Above posts correctly addressed your question. Sorry for the bogus response.

1Zoom

Most heavy low X dimension boats run well with a Mirage, you may sacrifice a little top end but it will probably stay on plane a little longer. The four blade props will usually give you a little more stern lift and a better hole shot, however it is also harder on the drive.