nitrous V quench

is their a math formula that I can use to calculate how much the quench should be for a certain amount of planned nos to be used?

if it's 250 or less quench it like a N/A motor 250 plus the quench can be bigger.

The tighter the quench the smaller the tuning window

"The tighter the quench the smaller the tuning window"

true I get the tight versus moor open. small chamber head versus large chamber head who wins?


"0" deck + .043 gasket=.043 quench for 250hp nos




fill it in for a say 750hp shot?

For a 750 hit

2 kits or 3 I would want  60-65 possibly a little more....

My little motor will be on 300 my quench is 45 its on the tight side but it's ok worst that can happen is melt a couple of pistons...lol

"shit man" this is real world racing= 1 Kit

I have been down this road many times trying to use .020 in the hole + thicker copper gaskets any were from .043-.080.that would net .100 quench with the .080 and still not getting but 20 decent runs on the gaskets.

I'm not much for copper gaskets had a set 1 time and never again a good MLS gasket is what I use...

Make sure the deck is flat and head is flat

Is this conversation not a little limited by looking for the only optimum quench for high doses of NOS, when there are many other factors that will affect the numbers and their ability to survive, efficiency(cam profile/flow), air intake/fuel octane, timing, compression, temps, coatings etc. It could just me missing the point but there is optimum numbers, but they can be achieved differently.

^^^^^ this is very true but he only asked for quench

I am in the process of building a new motor and will never use copper again.pistons will be .060 in the hole with a .040 cometic =.100 quench and the heads chambers will be resoftned.


why do the GM heads seem to be better than ours for nos?i think its the larger chamber in the head + the 18-24* valve angles moor nos friendly.

something I have learned is the fast burn p51's chambers will give you a false reading on the plugs once you get above a certain jet size.in other words the plug will show lean and it will be the opposite.so watch the header flames when making a tuning decision.

gmsmkr wrote:^^^^^ this is very true but he only asked for quench

"true" but I am open to all of it........I am tired of all of the chevy domination.i have spent some serious coin over the last 4 years trying to be solid in the 4's not just once in the while.

saying that I think I have been lead down the wrong road by 2 want a be GM motor builders

Larry T wrote:I am in the process of building a new motor and will never use copper again.pistons will be .060 in the hole with a .040 cometic =.100 quench and the heads chambers will be resoftned.


why do the GM heads seem to be better than ours for nos?i think its the larger chamber in the head + the 18-24* valve angles moor nos friendly.

something I have learned is the fast burn p51's chambers will give you a false reading on the plugs once you get above a certain jet size.in other words the plug will show lean and it will be the opposite.so watch the header flames when making a tuning decision.        

The false reading on the plugs makes me I am guilty of running my sh!t fat at an idle/low rpm which does give some bad readings on the happy gas when the accumulated carbon sandblasts the plugs, but fat doesn't melt stuff. Maybe SJ will chime in but I have a whale of a time balancing the street tune with the fog tune to be safe at higher elevations, the race only tune is as fat as it needs to be to not melt stuff, it may have a little more in it off the fat tune but I do not have the electronics to set the curve. The tight chamber stuff will run efficiently but only up high, and if it ain't melting its working.JMO

Imo the fast burn stuff should be on the street.what im thinking is a decent chamber softened that will carry a large charge with out carrying all the heat and pushing out the gaskets.then again quench is a factor in all of this also.........




whatbumper were are you?

Mr. Stupid here but why cant you move the pin down on the piston deal ? to increase quench ??

bruno wrote:Mr. Stupid here but why cant you move the pin down on the piston deal ? to increase quench ??

yes,but it will move the bottom ring lands lower in the pin hole.my solution was to buy new rods and move the pin hole down in the rod.

So is the consensus that a large hit of nitrous requires a large combustion chamber ? Or am I reading that wrong ?

Large chambers give you a lot of benefit. Slows the burn, gives more space for combustion to happen and a bigger tuning window. We shoot for the .085-.100 range on our nitrous customers based upon a lot of variables such as stroke, bore, chamber design and rpm. Stroke and rod length matter too as we want to know how long that piston sits a tdc.

I have been known to complain about not having any great bbf nitrous designs but that was mainly in relation to the X275 class. The small chambers of the "A" head just are hard to control.

Now, one thing that is hard for a lot to understand is comparing what's best for NA horsepower vs nitrous horsepower. As an example we had a car on the dyno Friday night that has an IS fogger on it. He runs a limited class so is limited to a .036 jet. On motor the car is a turd. Only makes about 690 at the tire. 588 bbc with head hunters. Awesome setup. On the 36 jet it makes 1148. Wakes it up a little. A 36 pill is not more than a 500 shot. Obviously these are tire numbers.

It makes the motor happy though.

As a summary, I don't think there is a magic formula but I will say that there is no comparison between big chambered motors vs small chamber no matter what the brand.

But then again many people have different opinions. We just know what works for us and doesn't burn stuff up.

Where is the HeRo when we need him....I don't think he is having any head gasket issues.

Oddly enough, the C460 has smaller chambers and a lesser valve angles than the A460, but the A460 package is the 'fussier' of the two.

I suspect there is more to it than just chamber size.

Lem Evans wrote:Where is the HeRo when we need him....I don't think he is having any head gasket issues.

Oddly enough, the C460 has smaller chambers and a lesser valve angles than the A460, but the A460 package is the 'fussier' of the two.

I suspect there is more to it than just chamber size.  

agreed about comparing the C heads. i don't have head gasket issues at all with the BBF stuff. It's when we try spray the 58's or bigger that we have issues with pistons. We have tried everything to slow flame travel with these motors and have data from some of the best engine builders in the world to try and make them live. All I'm saying is that if I was building an X nitrous motor right now it would be Chevy.

I don't have any C head data with nitrous but do with turbo's and we are able to get those packages to do exactly what we want. And we ran dished pistons just to keep the compression out of the diesel range. LOL

There are people that have got there with the sprayed A460 & C460 engines, but they had to plow their own ground. Some of the nitrous gurus seem to want to treat the BBF stuff like it's a BBC.....viewing the Ford engine like they are wrong rather than merely different.

Lem Evans wrote:There are people that have got there with the sprayed A460 & C460 engines, but they had to plow their own ground. Some of the nitrous gurus seem to want to treat the BBF stuff like it's a BBC.....viewing the Ford engine like they are wrong rather than merely different.  

makes sense. I'm probably guilty of the very same thing.

Just some stuff to think about. There were some interesting comments about squish velocity over at SpeedTalk  last year...here are some of the comments.....copy/paste.

  Squish velocity is determined by three factors: piston to head clearance, squish area ratio (piston area/squish area), and piston speed. All three must be considered along with ignition timing.

At a given clearance and area ratio, squish velocity will increase in direct proportion to rpm. If this serves to increase flame speed, then the combustion pressure curve could move toward TDC causing negative work prior to TDC. The igntion timing must be adjusted to reflect the effects of increased flame speed.


copy/paste

Would it make sense then to not run as much compression on the BBF's as the chevy's do ?

Flame propagation velocities are rather slow. So slow that they would not travel across the combustion chamber in the time available. To increase flame speed and reduce burn angle, chamber turbulence is created by use of inlet air motion (swirl, tumble) and by piston air motion (squish).

Squish velocity is the speed at which air is displaced from between the piston and head surface as the piston approaches TDC. It is the result of three factors: clearance, area and piston speed.

The vertical distance of the piston from the head (or chamber) surface is called squish clearance. As clearance decreases, squish velocity increases.

The area of the piston in close contact with the head, relative to the total piston area is called the squish area ratio. The higher the area ratio, the higher the squish velocity.

The piston velocity contributes directly to squish velocity. The higher the piston speed, the higher the squish velocity.

An engine with excessively high squish velocity will burn too rapidly, causing combustion pressure rise at or before TDC.


copy/paste

66 cc chambers, .110 quench, comeic gaskets, sprayed two kits for over a season w no issues....well i did have a cracked valve cover leak a tad of oil of you wanna call it a "issue".