Velocity Stacks & High Compression Pistons

E

Edo

Experienced Member
Joined
13 May 2000
Messages
990
Location
Lake oswego, OR
I am currently looking into getting the JUN high compression Pistons and possibly the Velocity stack set. Both are VERY expensive and end up costing as much as installing a Supercharger. I'd like to know if anyone has tried either of these two items? Does anyone know anything about the performance difference that these two in combination might offer?
And lastly, how do you filter air that goes into velocity stacks? Wouldnt that defeat the purpose of having them?
 
The Jun pistons requires boring of the cylinders, it increases the displacement to a little over 3.0l (I think stock is a little under 3.0l) They are made by Cosworth from England. I guess you will gain no more than 10hp, but at all rev range, since you increase the displacement. It's compression ratio is 11.5:1

You need to figure out some airbox solution for the velocity stacks mod, or you will be killing your motor pretty quick. (maybe SoS' new rear hatch would provide a solution) You'll also need a stand alone CPU to control all 6 throttle bodies. The individual throttle bodies gain about 20hp, but that depends on the size of the air horns you use. Contact TWM to see if they will sell you a custom kit. The revolution unit sold in Japan is a TWM Porsche unit modified.
If you do these mods, I would fly down to Vancouver and steal them off your car,
biggrin.gif
hehehehe.

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http://clubs.yahoo.com/clubs/maomaosnsxmodclub
My club for infos on my NSX.

[This message has been edited by maomaonsx (edited 03 April 2001).]
 
Originally posted by Edo:
I am currently looking into getting the JUN high compression Pistons and possibly the Velocity stack set. Both are VERY expensive and end up costing as much as installing a Supercharger.
Click to expand...

How expensive are the pistons? Keep in mind that you can get custom forged pistons from JE or Arias pretty reasonably, so I can't imagine paying a lot more for the JUN parts.

As for the velocity stacks, you can set up an air cleaner that fits over them and will allow them to still work efficiently. Look at an older European endurance race car or some of the vintage road going Ferraris for an example. As long as the velocity stacks have some room inside and the air can get into them easily, they will do what they are designed to do. Some of the heavily modified muscle cars from the 60's also solved this problem. The other problem with them is that with a filter on them, you are going to loose most or all of your rearward visibility. Depending on the size of the stacks, you may also be able to find little filters that fit on the tops.

While I like the philosophy of building a high hp NA motor, I don't know if it really makes sense when there are good forced induction solutions available.

Also, you will definately need a good programmable engine management system if you are going to run 11:1 or higher compression on pump gas.

Another thing to keep in mind is that if you build a high hp NA motor, you are going to spend a lot of money to get less than forced induction could do and most of the hp gains will be at very high rpm. It would probably be a frustrating street motor.

This is not to say you shouldn't do it; just be aware of the problems you will need to overcome.

My .02.
 
The JGTC NSX' (ie Raybrig NSX) work in the same fasion. The cars have a vent that passes through the rear hatch on the top. The airflow from this vent then passes through a air cleaner (similar to the UNI filter element) which are sandwiched over the air cones.

N/A power approaches and weight reductions are always respected by me :-)

-- Chris

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www.ScienceofSpeed.com - Click for more info
www.NSXClassifieds.com - The internet's only exclusive NSX Classified site!
 
10hp from the pistons..Hmm I believe JUN's pistons only run about 2500 or so, which is fairly close to the JE pistons from what I can understand. Also, if I bore out the Cylinders to maybe 3.1L or so, wouldnt I gain quite a bit more than 10hp? Just the compression alone should get me more than that.
Also, the kit I am considering (cant remember the name off the top of my head) costs roughly 6000 dollars, but comes with its own pre-programmed CPU I believe. Rearward Visibility isnt that big of an issue as far as I'm concerned.

Do the velocity stacks give you a much better throttle response? How do they sound? Do they kill your bottom end torque?
AAGH questions questions questions.

Chris: whats this SoS rear hatch George is talking about? I think I may need it soon.

George: If you're coming to steal my stacks, then I'm going down to steal your exhaust.
 
Edo, are you referring to the revolution throttle kit that lists for JPY750000? If so, that price does not include CPU and harness kit.
Some examples of tuned cars HP:

Revolution:
Jun pistons, headwork, straight exhaust, throttle bodies, 360hp

Phase:
Jun pistons, straight exhaust, 320hp.

But these numbers are jsut peak numbers, I'm sure the higher compression and larger displacement of the Jun pistons would do wonders for the low end.

The HP increase of the velocity stacks depends on the length, and size of the air horns, and the tuning of them. The stock intake has variable chamber to give power both at lower end and top end. The velocity stacks would require you to chose just one range to squeez out the most hp. But I'm sure the throttle response would be amazing, s well as the sound!

So, as you can see, not much HP for lots of money. But the pimp factor of 6 throttle bodies sticking out of your engine bay is just out of this world. I love the idea of high N/A power, light weight, as well.



------------------
http://clubs.yahoo.com/clubs/maomaosnsxmodclub
My club for infos on my NSX.
 
Ok, that does it, I think I am going to order that throttle body kit.
The one I saw had blue stacks and was listed for 650,000Y and came with its own computer. I will check the brand tonight.
Also, George do you know of any LOUD exhausts made from Japan that have the exhaust tips in the stock location? (Not in the middle like yours)
 
The Spoon exhaust has a very meaty tone. You'd be wasting your money to buy an exhaust from Japan if all you want is loud (IMO). Your local exhaust shop could build you something with supertrap cans.

-- Chris

------------------
SoS_logo.gif

www.ScienceofSpeed.com - Click for more info
www.NSXClassifieds.com - The internet's only exclusive NSX Classified site!
 
Don't get the spoon, it's not very good. I would recommend revolution, arc, or Advance, if you don't want the center-out Taitec.
But then Chris is right too, if you just want loud, you can just make a set of straight pipes that goes from the headers, or cat-back.


------------------
http://clubs.yahoo.com/clubs/maomaosnsxmodclub
My club for infos on my NSX.
 
I've already got the supertrapp's but have been having problems with it. Hence the thought of getting a better exhaust.
Yes they are louder than hell, and they sound decent to boot (under throttle) but they sound like crap when under engine braking.

I think I'm going to jump in on George's Taitec Group buy. Taitec + Jun pistons+Velocity stacks...
Whoohaaaaa
I'm ready for some Boulevard Pimpin' now...
 
I think if HP/Dollar was our main concern, we would have all bought Mustang 5.0's and thrown a Nitrous Kit, Suspension Kit, Brake Kit, Exhaust Kit, and a 500hp total Engine buildup with a 12psi Paxton Charger for under 6000 dollars.
THATS HP/dollar...
a 1500 set of headers from RM racing that nets you 8 hp is NOT cost effective.

So I figure, hey I'm already into the grossly non cost effective range, why not just go all the way.

I'm crazy.
 
Ok, I am now down to 2 kits. Revolution, and SS works.
Both are roughly the same design, but vary greatly in price.
Revolution sells for roughly $7500 without a CPU or fuel management sytem.
the SS works kit says that it is some sort of Carburetor kit, and requires NO Cpu...I dont pretend to be a genius at cars, but WHY would you want to switch a fuel injected car BACK to a Carbureted setup with velocity stacks??
 
Originally posted by Edo:
Ok, I am now down to 2 kits. Revolution, and SS works.
Both are roughly the same design, but vary greatly in price.
Revolution sells for roughly $7500 without a CPU or fuel management sytem.
the SS works kit says that it is some sort of Carburetor kit, and requires NO Cpu...I dont pretend to be a genius at cars, but WHY would you want to switch a fuel injected car BACK to a Carbureted setup with velocity stacks??
Click to expand...

I would not want to switch to carbs. While they can get more top end hp on big hp engines that use a LOT of fuel, they are really a step backwards 99% of the time and you will lose throttle response and tuning the car will be a major pain in the ass.

It is just my opinion, but I really believe if you are going to tinker with your car like this, you should go to a programmable engine management system. That way, any time you make a major change, you can adjust the fuel and timing to optimize performance. My .02.
 
I am assuming that a decent fuel management setup will be completely adequate for this setup. Nothing exotic is going to be necessary to manage velocity stacks is it? Does anyone know of a person who has gone with this setup? or am I treading on "New territory?"
 
New territory in the US by any means.

If you go the forced induction route, you'd only be spending a couple grand more.

Wait a few months, and you may be able to find a SC for the NSX for several thousand LESS than what you're planning to pay for air cones.

-- Chris
 
By the way, George's car has a great ass, but isn't anyone here concerned by his car always "mooning" us?

-- Chris

------------------
SoS_logo.gif

www.ScienceofSpeed.com - Click for more info
www.NSXClassifieds.com - The internet's only exclusive NSX Classified site!
 
Originally posted by ScienceofSpeed:
By the way, George's car has a great ass, but isn't anyone here concerned by his car always "mooning" us?

-- Chris
Click to expand...

I'm sorry Chris, but I have no choice. That is the only view you'll be seeing of my car at Tunderhill...ouch!
hehehe

BTW, I like the handling of your car too. the CT bushings makes a huge difference!

------------------
http://clubs.yahoo.com/clubs/maomaosnsxmodclub
My club for infos on my NSX.
 
Has anything come of this?

I searched around for all the headwork, extrude hone, velocity stack, cams, and pistons threads, and found a decent amount of info. Has anything panned out in this subject matter?
 
Well, my Mom now owns Edo's NSX, so I don't think so.
smile.gif
But I would love to hear if anyone else has given this a try? Anyone?
 

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