Debate: Whats the best Boost/ N2O Combo?

[staticpike]

Okay, since my return from the south pacific, I've been reading all the posts from the last hundred days trying to catch up. I've noticed that our own Shirl has broken the barrier to th 11 sec range and did it with what many consider an "unlikely combo" of boosting and juicing; which was considered by many to be a bad combo (better to just go one way or another.

From reading through what she has told us on this board, she did it with a boost a pump (necessary to supply fuel to all that air), a drive shaft (most likely a small factor in the over-all equation), a full exhaust (every enthusiasts first and most necessary mod), good tires, great weather, and the real magic in it - 6lbs of Powerdyne pressure and a 100 shot of N2O.

For the purpose of this debate, lets assume the cars have a similar setup; i.e. a fuel system capable of handling whatever you do (walbro, boost-a-pump etc), good exhaust, good tires, and good weather (all the basics). Lets also assume its a stock engine (no new internals) since the discusion would change dramatically with cams, heads, pistons, etc... What I want to discuss, is 6psi/100hp the best combo? I mean, what if a person ran 7psi/85hp or 10psi/75hp or whatever combo? There has to be some kind of curve to figure this out for a given application right?

I remember when I first started at this board way back when, I liked the idea of boosting & juicing at the same time, but it was quickly written off because it was more practical to go one way or the other and was promoted as a waste of money otherwise. I wrote it off as so (being a newbie) at the time, but now we all see that it is possible and what it can do (reading around, I already sense that people are adjusting their cars accordingly to mimic Shirl at least I know I am...)

So what is the best combo?

PS - Shirl, I hope you don't mind that I'm analyzing the way you did this. In fact, I'm hoping that you will chime in and share with us what you know so we can all benefit. Maybe your mechanics had a great reason to go with the 6psi/100hp combo - but I don't know, thats why I say it's worth exploring!

[Tiago]

From my experience, nitrous seems to be quite harsh on the motor, I mean multiple people including myself have blown motors on 85-100 hp shot even with proper setup systems, trust me I know. Now boost is quite "soft" on the engine it seems. Gains of 200rwhp 230rwtq are seen on my car another prototype car gained 300 rwhp 330 rwtq, on engines that last with these gains. Now has anyone tried a 200 shot on a stock 3.4? it will granade so quick it wont even be funny. See what Im saying?

IMO due to the destructive nature of nitrous I would use it to aid spool/cool intake temps only, lots of boost, 50 shot max to cool things down would be the money mix in my book.

[12secondv6]

<--- 100 shot, spun to a 12.4 w/ a 1.7 60 foot

<--- 125 shot, spun to a 12.5 w/ a 2.0 60 foot

Nitrous only! [img]tongue.gif[/img]

[Timbo1969]

Well by the numbers so far, Turbos > Superchargers. Nitrous > Turbos. Nitrous + Supercharger > Turbos only, Supercharger only, and Nitrous Only. That's what the numbers say so far on the track.

[staticpike]

Well, I'm sure that we can all agree that any power-adder is going to add a certain amount of instability to a stock engine. I'm even willing to bet that we'd all even agree that nitrous, even though it was the ruling champion on this board (and still partially is), is definitely the most unstable of our 3 options.

Does anyone know what kind of N2O setup Shirl was using? Was it wet or dry? Did she spray all the way through or just to spool? Is her nitrous jet before or after the powerdyne?

I'm can't argue that boost isn't a better "all-the-time" power adder - it is. But I also can't argue that N2O isn't a great leap forward when you need it, and gives you that little something extra when you want it.

So is there a better boost/N2O combo than 6psi/100hp? Could one possible increase either or both on our engines? I know our engines our fairly high compression meaning they are better suited to N2O than boost (I think I'm right here, if not, correct me) but fortunately, they are a proven combo that can work...

[John_D.]

<blockquote>quote:</font><hr>Originally posted by staticpike:
Does anyone know what kind of N2O setup Shirl was using? Was it wet or dry? Did she spray all the way through or just to spool? Is her nitrous jet before or after the powerdyne?

So is there a better boost/N2O combo than 6psi/100hp? Could one possible increase either or both on our engines?<hr></blockquote>

She said she was running a wet kit. I don't know about whether it was all the way or not, but I would think it would have to be for the duration of the run, to account for the difference in her blower-only time vs. her combo-time. (13.x to 11.8)

The best place to spray would be after the blower, to get the maximum cooling effect on the air charge.

The 6 psi just happens to be the most attainable with the powerdyne due to belt slippage issues.

The ideal setup for pure rwhp would be nitrous only, because all the added power goes to the crank. For instance, if you want 400 rwhp, and it takes 480 crank hp (apx. 18% drivetrain loss), then you only need to produce 480 hp load on the engine. If you run a blower that takes 50 hp to drive, then you need to produce 530 hp load on the engine, 50 goes out the front to drive the blower, and 480 out the back to the drivetrain.

The point being that bigger boost probably means bigger parasitic loss to make up... That's for the supercharger. Turbo is different, but similar.

At some point, more boost means an intercooler is needed, which requires even more blower pressure, to achieve the same intake pressure...

For me, I wanted more power on the street too, and the nitrous runs out too quickly. So a combo is my current direction.

But if I was going for an all out e.t. record, I would probably try to do it all with nitrous so no engine hp was used up on a blower, and all of it went to the drivetrain.

With that thought in mind, I tends toward small boost (6psi) and 100 shot or bigger, for drag racing applications. And medium boost (9-10 psi non-intercooled) and a moderate shot (50-75) for the street.

One thing I found with nitrous, when I tried to run bigger than a 150 shot, is I couldn't deliver it fast enough. I still got a strong pull off the line, but my trap speed dropped when I jetted bigger in the same night, and my et dropped a little. I don't know if it was the line, the filter, the valve, or the single nozzle. I know the LS1 dry kit comes with two nozzles... So there's more to research on the side of running a huge nitrous shot.

That's all I can think of. [img]smile.gif[/img]

[Arctc Wolf]

staticpike, I think shirl also had a TC in her car, which helps tremendously. The best thing for our cars seems to be a good launch. we don't have very high hp numbers to get us great trap speeds, so most of us require a killer launch to get us great times. Getting all the power to the ground is very important on our cars. This is why when people upgrade their drivetrains and suspensions, especially on A4's, their times drop substantially. Shirl knew this, and so she built her car up to launch as quick as possible, and then rely on the nitrous and SC for the top-end.

neways, back to the main topic. I agree w/ tiago in his saying that the boost is "softer" on the engine. a 100 hp shot of nitrous hits the engine harder at 2500-3000 rpm than a partially spooled turbo or SC(I know sc's don't spool, but I hope u guys know what i mean). Also, our motors are built for normal atmosphere operation, not nitrous. nitrous has more oxygen in it than air does, meaning more power. want an even bigger boost in power, try injecting pure oxygen into the motor. problem is, the combustion wouldn't be controled very well, and would prolly blow the motor. this is because the trace gasses and nitrogen in air and nitrous help control the combustion in the cylinders, since they aren't really burned to produce power.

I feel that either a small dry shot after the sc/turbo/intercooler, such as 25-60 would be good for cooling. for a more precise mixture, and direct port setup with a moderate shot, 50-85, would be ok with say 7-8 psi boost and tuning.

[Shirl]

The converter is STOCK. (Although I do have an Edge converter waiting to be installed.) Static, it's all about experimentation. These were my ideas and my dreams and they were put into action little by little over a long period of time. This is not an overnight or even a one year ordeal. This has been a period of many years. Racing is NOT my #1 priority, showing is. And yes, I have someone that has helped me immensely but even he has said.."nitrous is too violent on the motor, you don't want nitrous". If you listen to everything people say..and have to ask THEM if it's ok, then you might as well be a puppet in life, and forget about what YOUR goals are.

[AZ3.8Camaro]

I think a progressive controller could "ease" a big shot into a motor, just like boost.

[Black01GT]

i would have to agree with building the bottom end...but just the rods, pistons, bearings and espcially the rings. get the best rings because theres gonna be a lot of cylinder pressure in there. i would think the safest way after that is get a good tune with a VERY careful eye on the A/F ratio, like a EGT gauge or on a dyno.
not only is the nitrous cooling the intake charge from the blower (a good anti detonation), its adding more oxygen, which needs more fuel so you dont lean out causing your EGT to go through the roof