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brian said:
what does this do exactally? retard timing, control boost?? I have seen this before but not sure the mechanics of it.
It is a 2 Step Rev Limiter. It builds 5-7 psi out of the hole. It cuts out fuel on one of the cylinders when compressing. It makes the turbo build boost without load on the front tires.
 

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Living up Boost
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Wouldn't that cylinder run super lean!? I don't understand...that sounds like it would lead to detonation.

-saaby
 

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Saaby said:
Wouldn't that cylinder run super lean!? I don't understand...that sounds like it would lead to detonation.

-saaby
You are partially correct.

Sitting there constantly on the 2 step will heat up the exhaust housing and possibly crack it. It is not intended to use on the street, but it is fine if used only when drag racing.

Other 2 Steps that are on the market cut out ignition only, which floods the cylinder with fuel.
 

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sleeper
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It can't run super lean if there's no fuel at all! Remember, detonation is when the fuel preignites, or the flame propagation isn't smooth, etc. You get the idea.

But if there's no fuel, there's nothing to detonate. From what I can tell of how the drag launch program works.... well, in order to get the turbo to spool up, the engine has to be loaded in order to flow enough exhaust gases to spool the turbo right?

So what they're doing is cutting fuel to one of the cylinders and basically turning that one cylinder into an air pump. There's now a load on the engine caused by the compressing of the air in that cylinder. That load is enough to get that turbo to spool.

Man, that's badass, I've never thought of that before.... whoever came up with that idea is a genious.

Khiem
 

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Bingo!!!!!!

spdracerUT said:
It can't run super lean if there's no fuel at all! Remember, detonation is when the fuel preignites, or the flame propagation isn't smooth, etc. You get the idea.

But if there's no fuel, there's nothing to detonate. From what I can tell of how the drag launch program works.... well, in order to get the turbo to spool up, the engine has to be loaded in order to flow enough exhaust gases to spool the turbo right?

So what they're doing is cutting fuel to one of the cylinders and basically turning that one cylinder into an air pump. There's now a load on the engine caused by the compressing of the air in that cylinder. That load is enough to get that turbo to spool.

Man, that's badass, I've never thought of that before.... whoever came up with that idea is a genious.

Khiem
You hit the nail on the head! I bet you are an Engineer Major, huh?!?!?

Clark Steppler designed it!
 

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Living up Boost
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This is great. Thanks for the pearls guys. Now, there is still one thing that baffles me. WHY does there have to be a load on the pistons to spool the turbo. What difference does that make on the gases that are pushed out of the cylinder on the exhaust cycle of the cylinder to make the turbo spool faster? I assume that for the turbo to spool faster, the gases have to be hotter and/or faster moving, right? Well then I just don't see how the gases could become hotter and/or faster if there is load on the cylinder...

-saaby
 

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Now, there is still one thing that baffles me. WHY does there have to be a load on the pistons to spool the turbo
to spin the turbine on the turbo. air (whether exhaust or pumped air from the dead cylinder in this case) passes through a the exhaust housing on the turbo, which in turn spins the compressor, which forcefeeds the motor.

I assume that for the turbo to spool faster, the gases have to be hotter and/or faster moving, right?
yes, this is why the motor only builds 6-7 psi while on the 2 step, as opposed to the up to 20+ psi that many turbo cars are capable of.

my question is: can this be programmed into a JWT ECU or do you just buy the unit? what comnpany makes this unit that cuts the fuel?

also, on a T28 which is only boosting like 9-10 psi max, do you think it would still build 6-7 psi on the 2 step? that would be really cool, no turbo lag out of the hole!
 

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Saaby said:
This is great. Thanks for the pearls guys. Now, there is still one thing that baffles me. WHY does there have to be a load on the pistons to spool the turbo. What difference does that make on the gases that are pushed out of the cylinder on the exhaust cycle of the cylinder to make the turbo spool faster? I assume that for the turbo to spool faster, the gases have to be hotter and/or faster moving, right? Well then I just don't see how the gases could become hotter and/or faster if there is load on the cylinder...

-saaby
Yeah, graduate in May in Mech. Eng. :) Anywayz, think of it this way. The higher the load on the engine, the more effort/power it puts out; i.e. the more air and fuel goes through the motor which leads to more air thru the turbo which gets it to spool. If you just sit in neutral and rev the motor, there's no load, so not that much fuel or air is going to go thru and the turbo won't spool.

Sorta like riding a bike, stick it in a really low gear and go downhill; you can pedal as fast as you want but it won't take any effort will it? It's basically because there's no load on you. Now you start going up some massive super steep hill and you'll be cranking as hard as you can and put out a big effort because now there's a load.

So that dead cylinder not getting any gas is now an air pump which creates a load for the other 3 cylinders. It's like using an air pump to pump up your bike tire, it takes effort. So those 3 cylinders have a load on them so they put out more effort which means they need more air and fuel which gets spit out to spool up the turbo.

That Clark guy is a genuis I tell ya!

Khiem
 

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HotshtSR20 said:



my question is: can this be programmed into a JWT ECU or do you just buy the unit? what comnpany makes this unit that cuts the fuel?

also, on a T28 which is only boosting like 9-10 psi max, do you think it would still build 6-7 psi on the 2 step? that would be really cool, no turbo lag out of the hole!

The "Drag Launch Program" is offered only by JWT. You will have to purchase a Nitrous Module to run the Drag Launch Program.

MSD makes the Digital 6, Digital 7, and 7AL2 that have a built in 2 Step Reve Limiter. These units cut out ignition rather than Fuel!
 

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The "Drag Launch Program" is offered only by JWT. You will have to purchase a Nitrous Module to run the Drag Launch Program.
yeah, i figured you would need the nitrous module, because it can control fuel and all that other good stuff based on throttle position, etc. does the program work where it sees that the clutch pedal is depressed (not sad) and cuts fuel to a cylinder?
 

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Ah what the hell I'll throw my $.02 here.

The turbo will create boost (spool) with or without load. The engine just has to be running above a certain rpm that creates enough exhaust flow to spin the turbine fast enough to make boost. On small turbos, anything over 3500rpm will spool the turbo. Load on the engine has nothing to do with the turbine "spooling".

JWT's trick is to fool the bypass valve or BOV into closing by sending it a low vac reading. This allows the engine to run boosted without actually having a load on it.

Ok now it's simple to figure that you could create the same condition by temporarily removing the signal to the bypasss valve/BOV with your left over EGR selenoid and a switch.

For a rev limiter: the cruise control comes to mind. Ever have it on cruise and take it out of gear without the clutch? With a little effort you may be able to use the cruise control as a rpm switch.

Take it for what is worth.

Cheers,
Charlie :)
 

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CharlieH98 said:
Ah what the hell I'll throw my $.02 here.

The turbo will create boost (spool) with or without load. The engine just has to be running above a certain rpm that creates enough exhaust flow to spin the turbine fast enough to make boost. On small turbos, anything over 3500rpm will spool the turbo. Load on the engine has nothing to do with the turbine "spooling".

JWT's trick is to fool the bypass valve or BOV into closing by sending it a low vac reading. This allows the engine to run boosted without actually having a load on it.

Ok now it's simple to figure that you could create the same condition by temporarily removing the signal to the bypasss valve/BOV with your left over EGR selenoid and a switch.

For a rev limiter: the cruise control comes to mind. Ever have it on cruise and take it out of gear without the clutch? With a little effort you may be able to use the cruise control as a rpm switch.

Take it for what is worth.

Cheers,
Charlie :)
Bro, you are way off. Please do more research.
 

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ok so its not the full cost of the nitrous programming...i know it uses that and that got me thinking, well maybe its more...i dunno

thanks!
 
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