VELOCITY STACKS v. CENTER HORN??????

[jeffbare]

What is the differane between Velocity Stacks and a Center Horn?

[Tony Brucato]

Hi Jeff,

Are you asking about the velocity stacks like on the SVS versus the center horn?

If so, the big difference is the ability to take better advantage of the expansion and compression waves with the velocity stacks. By changing the length of segregated runners you can drastically alter the power curve of the engine. You can easily change the runner length of the SVS with the addition or removal of velocity stack spacers.

On the center horn motor the reed plate acts as velocity stacks as well, and this is where the air starts to segregate. You can add the Mercury spacer behind the reed plate to lengthen it as well.

If you look inside the center horn you can see that the air going to the two center cylinders have a pretty straight shot from the horn. The top and bottom cylinders have a lot more twists and turns to make.

In an effort to straighten the airflow to those cylinders, some people angle cut the reed plate. This will alter the pulse tuning effect on those cylinders though.

Another difference that the SVS has is the guillotine slide that leaves an unobstructed path to the reed cage at W.O.T.

[jeffbare]

Are you asking about the velocity stacks like on the SVS versus the center horn?

I guess I really don't know what the SVS is, so I might be having a hard time clairifying my question. I am trying to increase my full power curve with out hurting any part of the accelleration, topend, ect... I also don't want to do anything that will cause my motor to any less reliable.

[jeffbare]

ttttt

[jeffbare]

I took a look at your SVS system, and now know what you are talking about. That isn't what I had in mind, I was looking at the Velocity Stacks or Center Horn that is just a bolt on that you can get for $65 from Rick Racers or Bobs Machine. I like what you offer, and see the advantage, but the cost is a little more than I want to spend on this boat. Thank you.

[Alan Power]

Jeff, velocity stacks are carb bolt on's and the centre horn is the air intake for efi motors. Velocity stacks straighten out the airflow into the carb.

[jeffbare]

That is exactly one of the questions I need to know. The other is: Is there really any benefit of installing the velocity stacks with the 1" spacer I am installing.

[hydroholic]

There is no gain or loss that you will notice in installing velocity stacks on carbs.The only thing it will change is the look and you will probably have to rejet your carbs,but you will not see any gains in rpms or horse power.They will not add or take away from the pupose of the spacer you are installing neither.As far as performance goes they are a waste of money.If you are looking for performance and not looks,spend your money elsewhere.

[Alan Power]

I am by no means an expert so don't quote me on this, but in my opinion if you need to rejet you must be making power. You cant make power without fuel so if you need more fuel you must be making power:confused: If this is not right I'd realy like to know what the case is!

Alan:)

[hydroholic]

Most of the time you can get buy without rejetting when you add velocity stacks. I always put them on my carb motors just because they look better than the flat front of the carb when you remove the air silencer.But they DO NOT enhance performance.I have put them as I said on all of my carb motors because I do like the way they look and I have had two motors that when I added them I did rejet the carbs because they showed a little more towards the lean side than before and since I was running higher than stock compression on pump gas(145psi) I felt it was better safe than sorry.It still did not make any difference in performance that you could notice anywhere through the rpm range and it did not make any difference in the rpms on the tach neither. I understand what your thinking is on the matter Alan, but thats not always the way it works. Usually if you have to rejet it is just one size and you will not get a noticeable difference I will assure you.You can ask some of the guys on here that have ran these things and have more experience on the matter than I and they will tell you the same,performance wise they are a waste of money.I think RACE MAN said it best when he said on another post questioning velocity stacks,"YOU GUYS ARE HOWLING AT THE MOON FOOLING WITH THOSE THINGS!" I feel the same about tuners,have tried several different types that people have made claims of more rpm's and hp and find them just like velocity stacks,a waste of money performance wise.They may change the sound somewhat but don't really enhance performance.

[steve]

The spacer plate will help. Just be sure it is one thats clearenced for the shift shaft underneath it and that the openings are the same size as the reed cage openings. Some are and some are not. :cool:

[jeffbare]

Thanks every one. I think I might take the air box off and run it that way. If I can tell any difference I will probably go with the velocity stacks.

[jeffbare]

What do you guys think of adding the center horn to my friends 1988 2.4 liter EFI? He to is adding the 1" spacer.

[stv pro]

i have noticed a slight difference in response and overall power with the air box cover off a few of my motors, prob cause they are always run a tad on the rich side so being a lil bit leaner with the cover off makes more power- i always keep everything i run jetted slightly rich to be safe! oh yeah, and although the v-stacks look cool i have never bothered spending money on something that doesnt do anything-- looks cool doesnt matter, esp since the cover is on the motor! i usually run my motors with just the back side of the air box on since they have a venturi shape to them where they mount on the carb and seem to perform well like that..

now, im sure what you mean with "adding a center horn".. do you mean he is changing the efi system from the laser style to a horn setup?? there are 2 types of efi systems from merc on these "older" motors that i have seen--
-- there is the laser style system with the multiple butterflies and injectors before the reeds
-- then there is the horn efi with case injection, the injectors are mounted on the front half and spray right into the crank case..

the horn set up has a straighter shot in to the engine and makes more hp in stock form but either one is definately capabe of making good HP.. reeds seem to last longer and seal better having the fuel/oil pass through them like with the laser system..

i just typed this up quick between the phone ringing and kids screaming so i may have missed some things.. i hope some of this info might help but im not exactly sure what is meant by the whole a