I was going to PM Greg about this, but there may be others that can benefit from the answer so I will ask it here. What cam would you recommend for an evo running large amounts of nitrous (over 150 hp). I am in the process of designing an entire engine build around nitrous oxide. I want to maximize the cams, head design, and all other components to make the most power on the juice while maintaining decent power off of the bottle. What would such a cam look like. I am guessing a custom grind. Please share your thoughts. Thanks

 

150 shot is large but isn’t huge. I would suggest a slightly larger Exhaust cam duration if anything... what size turbo are you planning on running? What other items have you looked into as far as setup... or you can just complete this list for me.

Head
Ported Y/N
Valve Size
Valve Material
Valve Springs
If available Flow Data
Hydraulic or Solid Lifters

Short Block
Compression
Displacement Bore/Stroke

Intake Setup
Throttle body size
Stock or Aftermarket Plenum
Water or air to air IC

Turbo
Turbo Sizing compressor and exhaust if wheel sizing is available along with A/Rs
Header style or manufacture if custom: runner length, and size.

Desired Rev Range of the engine and also Launch RPM if applicable.

Fuel Type

 

Thanks for the reply. I would be glad to give you the specs. It may end up being more than 150 hp. I will not know until I start tuning. I will give it all it can take within some reason. This is what I am thinking so far.

Ported head. 1mm oversized valves (or at least exhasut valve)
Have not choosen exact material or manufacturer yet
2.3 displacment
Stock ported intake and throttle body
Air to Air IC
Fuel type for the big hit will be c16.
Max RPM will be 8000 or so.
Launch RPM will be around 5-6K I guess. Never driven a 2.3 on the track?

Turbo is where this project gets very interesting! I am going to run my little 20G for the quick spool up. Once it is out of breath, I am going to progressivly ramp up the nitrous to make up the difference and also take advantage of the decreased dynamic compression ratio of the falling boost which I will taper off through the BCS as the nitrous steps up. I know it sounds crazy, but this is what I have decided on and I think that it will allow the car to do many things well. Off the bottle response will be great. Drivability will be retained. And when on the N20 map, I should be able to rip into the 10's easily. I run a utec that allows 5 different maps switchable on the fly. I like taking a path less traveled.

 

That sounds pretty interesting.

 

Horrible idea actually.................sorry, I couldn't stay neutral like you asked me to

Running the 20g until it "runs" out and then hitting it with the bottle is a terrible idea. The turbine wheel in the 20g is going to end up being your limiting side of the combination and trying to hit an already "choking" turbo with nitrous just is not a good plan.

If you want to run the bottle use it to get a large turbo on boost and then leave it on. Problem with nitrous is it is TOO easy to make power and becomes very addicting.

 

I'm no expert, but this is how I see it working:

You use a EBC to set the wastegate (WG) to initially spike the turbo to 30psi or so, then taper off to around 26-28psi by redline. Nitrous comes on from say 5000 to 8000 rpms. At this point your limiting factor is going to be the wastegate, not the turbine wheel. If you have too much exhaust coming out for the wastegaste to handle, you will get boost creep. Because the turbo is about maxed out the boost may not go up, but shaft speed and intake temps will rise (if the wastegate can't flow enough air).

You may not have this problem at all. All may work perfect and the wastegate hole may be big enough for the amount of exhaust you want to flow. If it is not and you run into the situation above, you can work around it with an external wastegate. You could weld the stock WG shut and weld in a larger aftermarket unit. Alternatively you may also be able to run just the stock one when the nitrous is off, and then have a secondary external unit open up when you nitrous is on (a nitrous-on switch would activate a solenoid to open the boost signal to a secondary boost controller attached to the secondary wastegate)

EVOlutionary

 

A well thought out resonse! It is close to what I was plannnig. I was not going to push the turbo at all. Once it was creating peak power on boost, I was going to turn the duty cycle on the BCS way down and let the nitrous do the work at that point. I am not sure either if the WG can handle it or not, but like you said, there are options if it can not. A $20 hobbs switch to trigger a secondary wastegate would solve any WG problem quick. It will be trial and error. It always is when trying something that no one has done before. I fully expect this.

As far as David's response. You are just a nitrous hater. It may be a horrible idea or it may do everything that I want it to do. I won't know until I try. Not everyone is into the big turbo's and the expense and sacrifice that goes with them. I have been in a ton of evo's with big turbo's. Only 2 were fun on the street and and those guys spent at least 15K on engine and turbo. Some people do not mind the huge turbo lag. I do. I also can not bring myself to spend 8K on a turbo kit and everything that you need for it.

 

I think the think David is trying to say is what you put in you have to get out. The turbine wheel and hotside are going to be to small to allow all of the stuff you put in the cylinder out. I am not saying nitrous is bad. I ran a 100 shot on my stock turbo but you need proper scavenging to make power and not reversion. That can cause knock.

 

In effort to improve scavaging, I will be going with an overzised exhaust valve, and an exhaust cut out in the DP, possibly a 4" downpipe, and if needed a wastegate welded to the exhaust manifold. I can not imagine a Tial Wastegate in the manifold not taking care of it if everything else does not.

 

Please, do not ask me for my opinions if you are going to tell me how things actually work.

With that said let me be somewhat of a dick since that is what I am good at.

The problem with the small turbine wheel is the back pressure it produces, which continue to climb as RPM climbs if the engine continues to make HP as RPM rises. Which is going to be your case if the car is put together correctly. So the 4" downpipe you are planning is going to do NOTHING because the restriction is in the TURBINE WHEEL, the larger exhaust valves are going to do NOTHING because the restriction is in the TURBINE WHEEL.

Let me say this again, the problem with the combination you are trying to put together is IN THE TURBINE WHEEL. You have a wheel that is designed to flow enough exhaust gases for say 500 hp, which you can make on turbo alone and then you force the engine to try and produce more by hitting it with nitrous and you further increase the exhaust energy that has to pass through a turbine wheel that is already choking the engine.....................

I'm must some dumb *** though, build the cars how you feel fit.

 

David,

Where did I tell you how things actually work or imply that you were a dumb ***? You really do come off awefully strong. Am I not entitled to post an idea that you do not agree without you taking it as a personal attack? Just trying to have a well reasoned discussion, not trying to start an argument of any kind.

How does the turbine wheel become a restriction if much of the exaust gasses are bled off prior to entering the the turbine? This is a legitimate question. Not a pissing contest so please keep that in mind for anyone who wishes to respond. Civil two way disicussions are how people learn and how knowledge is advanced.

 

"It may be a horrible idea or it may do everything that I want it to do. I won't know until I try. Not everyone is into the big turbo's and the expense and sacrifice that goes with them. I have been in a ton of evo's with big turbo's.
In effort to improve scavaging, I will be going with an overzised exhaust valve, and an exhaust cut out in the DP, possibly a 4" downpipe, and if needed a wastegate welded to the exhaust manifold."

You did not say I was a dumb ***, I guess from the two things you said above I assumed you thought I was a dumb ***. You asked my opinion, I gave it and then you went on to explain how you were going to make it work anyway, do it anyway and said regardless of what I thought you were going to do it anyway. To me this means you either think I am a dumb *** OR if no matter what I said you were going to do it anyway, then next time don't ask my opinion if no matter what I take the time to write isn't going to make a difference. See what I mean?

I have absolutely nothing else to add. My opinions/comments will not make a difference anyway.

NAWS RULES!! Best idea ever, is that better?

Have a great day. Back to my hole.

 

I'm done with this. You are incapable of an intelligent discussion. We should all just take your word as gospel and leave it at that right? I asked for your opinion not for you to come on here and act like this. Have a nice day.

 

I explained why it won't work, it isn't just taking my word for it. I am not acting like anything other than a little annoyed that you would take the time to PM me to ask me to come to this thread and give my opinion and then after I give it go on to say that regardless of what I said (after being asked by you to give my input) you are going to try it anyway....................

Seems like a waste of my time giving out any opinion and facts to what the problems will be if they are going to be overlooked.

 

I agree completely. He's one of those that only wants your opinion if you agree with him, even though he asked for it.