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sgt1970-442

just a little fyi

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WakeGirl

Nice writeup. How much weight do you think that the boat lost with the mods that you mention?

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Lance B. Johnson

Right that's my thought. 600 seems much to small especially for a boat. Nice work.

A

Some people will say why not just reprop? But they don't get us gear heads :lol:

Edited by Ruffdog

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Woodski

Nice work, good post. An SBC needs 600 cfm of air @ 5000 rpm so throwing in some inefficiencies a 600 sounds a bit small for the application. The other traditional variant carb on these is the Weber carb which is a clone of the Carter / Edelbrock unit and they are 750 cfm units.

As for weight reduction he very close to 155 -160 #, and I will guess an aluminum intake which is another 25#. I have done a similar project on my Echelon and am at 300# total reduction. I deleted the circulation pump completely so the t-stat housing and pump combine for 30# gain. Other areas include total removal of rear seat (including the back, now just a flat panel), carbon fiber platform & a different fuel tank. All this targeted for slalom use. It has made a significant wake improvement & the SV23 hull likes weight out of the back for slalom. I have also noticed it is one of the better left-right balanced hulls compared to the SN196/PS197 etc.

@ Steve: what does your alternator bracket look like (per your write up a duplicate of the standard one?), I keep staring at that for some additional weight removal. How much does the original one weigh?

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Levi900RR

I love reading stuff like this.

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WakeGirl

That's basically one full sized person then. Not as noticeable in the LXi as it would be in a Response or Echy (or any non-diamond boat), but still noticeable nonetheless. I'm with Levi, I love this stuff.

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Woodski

It has been a lot of fun making / changing stuff and getting a nice improvement. The latest mods, basically taking ~50# off the transom has not only helped the shortline wake but also done a lot for the 15-22 off wake which is what all the newer boats are targeting, certainly brought a nice smile to the CFO.

It is interesting noting the improvement in wakes as weight comes out, but also noticing the current level the boats are being built to, all around 3000-3300 # for the 3 event ones. Back to the Echy/Response days they were right around 2500 #. The additional width of the newer boats allows them to spread the load so the wakes are really good, but imagine how good they would be with 5-800 # knocked off them.

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Levi900RR

You have any pics of the carbon platform?

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WakeGirl

It has been a lot of fun making / changing stuff and getting a nice improvement. The latest mods, basically taking ~50# off the transom has not only helped the shortline wake but also done a lot for the 15-22 off wake which is what all the newer boats are targeting, certainly brought a nice smile to the CFO.

It is interesting noting the improvement in wakes as weight comes out, but also noticing the current level the boats are being built to, all around 3000-3300 # for the 3 event ones. Back to the Echy/Response days they were right around 2500 #. The additional width of the newer boats allows them to spread the load so the wakes are really good, but imagine how good they would be with 5-800 # knocked off them.

With everything that they're putting in the newer boats, that would be a tall order. But you're right, & I wonder how many slalom guys read that & had their eyes light up. :lol:

So I don't think that I've seen the number, what does your boat actually weigh right now?

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Woodski

@ Levi: PM me w/ your email & I can send you a pic. It is not fancy, I am not a talented resin guy... it is light though, original was 30 this one is 7 # and really stiff since it has a foam-core base & some design aspects to make it very stiff.

@wakegirl: 2300#. Best way is to throw them a rope and say try it. Unfortunately for the hard core slalom addict, the market certainly demands a lot of the extras to make them viable for the market and of course the manufacturers have to respond to that. But, when you can do whatever you like, one can take liberties with the tools and play around. Certainly a lot easier to cut & drill in to a 10+ year old boat rather than a new one:) And really nice to spend a few hours, a reasonably small amount of $$$ and end up with a great result.

Edited by Woodski

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WakeGirl

So true on all counts. Yep, I'll bet your boat really skis nice.

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Michigan boarder

Nice work, good post. An SBC needs 600 cfm of air @ 5000 rpm so throwing in some inefficiencies a 600 sounds a bit small for the application. The other traditional variant carb on these is the Weber carb which is a clone of the Carter / Edelbrock unit and they are 750 cfm units.

As for weight reduction he very close to 155 -160 #, and I will guess an aluminum intake which is another 25#. I have done a similar project on my Echelon and am at 300# total reduction. I deleted the circulation pump completely so the t-stat housing and pump combine for 30# gain. Other areas include total removal of rear seat (including the back, now just a flat panel), carbon fiber platform & a different fuel tank. All this targeted for slalom use. It has made a significant wake improvement & the SV23 hull likes weight out of the back for slalom. I have also noticed it is one of the better left-right balanced hulls compared to the SN196/PS197 etc.

@ Steve: what does your alternator bracket look like (per your write up a duplicate of the standard one?), I keep staring at that for some additional weight removal. How much does the original one weigh?

Woodski, we touched on this a bit on my engine thread, but the Weber carb I have is also a 750cfm unit? My engine guy that took a peek on Saturday was quick to say "We'll need to replace that carb", to which I replied "Well, it's a brand new rebuild exchange, with a half an hour on it, can't we rejet it or something?". He picked it up and looked at it and said "Hmm. Well, the best thing to do is get your engine built, then put this carb on and dyno test it. There's no point in us putting a newer carb on if this can deliver what we need, and no reason to spend $800 on a bigger carb if it only gets you 5hp".

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Woodski

@Michigan boarder: not surprised, the Weber/Carter/Edelbrock carb tends to be viewed a bit like Beta v. VHS! Here is my 2 cents worth. A boat tends to run at pretty much steady state conditions with not a lot of throttle changes specifically when you are engaged in the sport of choice. The weakness of these carbs is the transient fueling, but per my last statement, that makes it low on the priority scale. The upside is they are pretty simple once you understand them, have a wide tuning range and one key reason they are popular in a boat, very safe as there are no gaskets or seams below the fuel line. Mercruiser used them for decades on lots of engine options.

Re-jetting is not the big issue on these guys, tuning & calibrating them is the key task. They flow plenty of air so getting the fuel mixture right is the trick. The Weber is the best of the three, the parts are better as they are Weber specific. Example: the needles are three step rather than 2 for the other versions so a better fuel curve. David Vizard has a book on carbs that goes through setting this carb up along with some mods. They work well, I used it as a guide along. My key changes included lightening the secondary air valve weights (quickens throttle response), larger accelerator pump jet size (40# if I recall), lightest needle jet springs & smoothing some of the casting material (typical blueprinting steps). I would have to go back and look at all my changes (I did get spare carb parts from the Weber engineer with several tips and suggestions on setup so I could play around).

FYI: my boat is every bit as smooth as the other EFI boats on the lake, so IMO, the carb is not a big limitation, but I do have to adjust the choke twice a year, as the bimetallic spring is not calibrated for my aluminum intake manifold (or maybe simply not correctly calibrated). No big deal, three screws & a slight twist and all good. as quick as checking the oil.

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ColinP

so whats the opinion of the Edelbrock 750cfm carb, (model 1410)?

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Woodski

I would think very close to the Weber version although probably not quite as adjustable in calibration through the entire range. Same basic carb as the Weber and most parts probably interchangeable. Should work well if you are replacing an existing spread bore carb.

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UofM_MXZ

I like the edelbrock although the similar Holley will most likely flow a bit more and be a bit more adjustable. I am biased as all of my chevelles have Holley carbs on them.

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Wayne

I always like to throw this into a "what carburator do I need" discussion. Let's take a 350 cubic inch engine and convert it to cubic feet. That gives us an engine that is 0.2025 cubic feet. Now a 4 stroke engine will suck that amount if air in every second revolution. So we take 0.2025 x rpm / 2 to get the theoretical need. At 6000 rpm that comes out to 607.6 CFM. This assumes 100% volumetric efficency meaning as an air pump it's 100% efficient which no naturally aspirated engine can ever achieve. I've seen data of hitting 92% on an optimally designed intake system. So that takes us down to 559 CFM. I've heard you should oversize usually for performance applications so a 650 CFM for the mild engines in our boats is plenty.

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sgt1970-442

wayne,

while the figures show one thing on paper, the lake time and actual gps, seat of the pants and less throttle to get to a certain rpm and speed in a shorter distance say different. I've also played with all kinds of carbs on my car and other buddies cars at the drag strip. i'm not saying that a bigger carb is always better but, if tuned correctly and used to its potential you can see significant gains.

I also feel gm must have known something we didn't as the quadrajets are as I stated 760-830cfm.

woodski,

the alternator bracket looks stock. I painted it black and nobody even knows it not a stock bracket.

saved about 4 lbs. stock bracket is about 7 lbs. as for total weight loss, i'm at 141 lbs so far and counting. the intake manifold

is aluminum and its what indmar installed at the factory. got a big surprise when I pulled it to change the heads.

I thought it was cast iron with the black paint on it and really grabbed ahold of it to lift it off and about ate the

carb when it was much lighter than I anticipated.. all in all i'm very happy with the changes that have happened over

the years and it is a very noticeable improvement. just thought some of you might want to hear what others are doing for improvements for skiing the course.

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Wayne

Sgt1970-442,

I have a OE quadrajet off a 396 cuin truck engine and it's rated for 670 CFM. The numbers you are stating sound more like big block carbs.

Also a bigger carb will deliver more air at lower throttle. Basically for a given throttle blade angle the bigger carb has a larger opening. I would call this perceived performance and not actual. Test two different size carbs at WOT and see how much different you notice. It won't be much unless the smaller carb was way undersized to start with. Also make sure both carbs are jetted properly hit the right air fuel ratio.

The only 350ish cubic inch engine I have seen that actually needs 800+ CFM revs around 8000 RPM.

Edited by Wayne

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Sixball

So my question is? If you are not on say a privet lake so you need to be at speed in the shortest time why go for H.P. ? I could see looking at torque at lower RPM.

To make H.P. you need fuel and air but our boats only gain a very small amount of speed with the increase of H.P.

Holly built me two sets of carbs for our car. They said it was over carbed with twin 1050s on a 337 C.I. We spent days testing with one of the top holly techs. We did get close to best E.T. but always off 1.8 - 2.5 MPH. No one thing ever gets you to the best it's always the entire package.

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Baddog

It has been a lot of fun making / changing stuff and getting a nice improvement. The latest mods, basically taking ~50# off the transom has not only helped the shortline wake but also done a lot for the 15-22 off wake which is what all the newer boats are targeting, certainly brought a nice smile to the CFO.

It is interesting noting the improvement in wakes as weight comes out, but also noticing the current level the boats are being built to, all around 3000-3300 # for the 3 event ones. Back to the Echy/Response days they were right around 2500 #. The additional width of the newer boats allows them to spread the load so the wakes are really good, but imagine how good they would be with 5-800 # knocked off them.

Post some pics of before and after on your wake, please.

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sgt1970-442

Sgt1970-442,

I have a OE quadrajet off a 396 cuin truck engine and it's rated for 670 CFM. The numbers you are stating sound more like big block carbs.

Also a bigger carb will deliver more air at lower throttle. Basically for a given throttle blade angle the bigger carb has a larger opening. I would call this perceived performance and not actual. Test two different size carbs at WOT and see how much different you notice. It won't be much unless the smaller carb was way undersized to start with. Also make sure both carbs are jetted properly hit the right air fuel ratio.

The only 350ish cubic inch engine I have seen that actually needs 800+ CFM revs around 8000 RPM.

wayne,

I didn't start this thread to argue and don't disagree with some of what you're saying. and fyi a 4150 carb of 750,850,& 950cfm have 11/16 throttle blades front and rear. i didn't list the other changes i made either. i never mentioned intake runner size, port volume and velocity, chamber cc, compression ratio change do to milling the heads, port matching the intake, cam change, and a few other mods that were done mostly for more low end torque. as i stated this was a seat of the pants feel and nothing that i did on a dyno to tell for sure. by the way we have dynode many olds motors testing different heads, intakes, cams and carbs, proof on the dyno has told us that yes you can over cam and over carb but found the biggest gains with carburetion. you mentioned wot and i bet for the masses on here that nobody's boat see's wot for more than about 5 seconds to get out of the hole. you hit the nail on the head though with a/f ratio and then read the plugs after a hard run and see what you have. hard to install a wide band o2 sensor in a wet exhaust. yes all of the q-jets came off of big blocks. last i checked 396 is a bb and i would bet even if its stock that a bigger carb would help.

at sixball, the changes that have been made started as weight savings and turned into adding more low torque with the choice of cam i changed to. it was not for a higher top end speed as 48mph is about all its ever going to do. getting out of the hole and having to not go wot to achieve 36mph in a shorter distance on the gps tells me that the carb needed to be changed after i saw the results from the 600 to the 780 carb. while i won't comment on twin 1050 dominators on a 337cid motor because i don't know the rest of the combo, it does sound like a lot. while i still have a bunch of holleys laying around i'm only using quick fuel carbs from now on, they are a very nice quality piece. i can't with its the entire package gets the best results either, that's why a lot of other changes that were made forced the carb change. i'm sure all of the newer boats with mpi and a computer could benefit from a programmer.

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sgt1970-442

so the numbers that we came up with on the dyno sheets show that my quick fuel 850 worked best lower in the rpms for both torque and horsepower for johns 388 motor.

blows everything about what has been said in this thread and the dyno sheets will prove what I said about seat of the pants feel..

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Wayne

When you say dyno sheets is this a plot of TQ and HP versus RPM? Post them up, for curiosity I'd like to see the plots with the AFR logged as well.

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Sixball

One thing I found well running our cars. Rules do not always work the same on all engines. Weather Ford, G. M. or Chrysler. What works on one my not on another.

Also how small of a change can make night and day difference whether it be in HP or torque and some times both. Oh ya and then to put a package together that works with all the other variables.

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