well, we already have baselines. 200mph has been reached by 450rwhp 928s
so, all you need is 33% more HP to reach 220mph. (and a lot more runway! )

so, 650hp will probably do it no problem. use the 2.2 gear box and you should have no problem.

mk

 

All those 200mph runs were done with the S4 body style though, which is a good deal better in the aerodynamics department than an early S body. I also recommended the 2.2 gearbox, it would make this run much easier, safer and more likely to achieve a successful result.

Dan
'86 928S 5-spd w/LSD

 

Mark, We usually have 5-10 miles to make our high speed runs. We also
start at 120+ mph. And as Dan pointed out, the 200+ mph runs were with
the S4 body style with aero mods. Brett will be doing his run on a ~ 2 mile
runway with a starting speed of ~60. So he'll need a lot more power to
hit 200 or more, like he is targeting with his S2. So 1000+ hp is not a bad
number to shot for.

 

This is very significant.

OB - .41
S - .38
S4 - .34

To drop down to a .34 (this is a huge drop BTW) Porsche redesigned the nose and the tail.

I would tape over the headlights and the fog / turn signal lights as well.

 

what fuel will you be using?

 

Those of you who mentioned the added heat due to combustion and had concerns about melting pistons, keep in mind that because nitrous is ridiculously cold, that you have a built-in intercooler effect.

 

Yes.

 

I have no dog in this hunt, but...

 

Why argue over the science, when Brett will be creating facts in the upcoming months?

 

If so, how?
Remember, you are the one that seem to discount some basic facts. Not to detract from the discussion here, but i am

You had the comment that i replied back to, regarding NOS not having enough 02 to make up the differnce in making 1300+hp. This was proved by the statistic that you noted of NOS only having 50% more O2. this is wrong to start, NOS has 100% more O2, because it is 50% more dense at any temp. PLUS, you left out the density diffence, even though you noted it not being able to make up the difference, adding to the o2 content needed to create near 4x the HP (and subsequently 4x the mass flow). If you have 2x the mass flow just do to NOS alone, what do YOU think the vapor state, and extremely cold NOS would due to that ? Simple calulation with Gas Law can be quite telling.
Plus, some real world information that when NOS is being used, intake air temps are driven down by near 70degree F. What do you think that does to the density? what do you think that would due to the temp and therefore density if most all the air flow was NOS , rather than ambient air?

Also, look no farther than the 7-800 turbo charged 2.4 liter engines that ive seen, to prove that doubling that with double displacement could be acheived in theory. I do know of 550hp on a 2.4 liter running 26lbs of boost.
double that, and you get 1100hp for 3x atomosphere. (ie 2bar boost)
If NOS alone does 1bar boost, if used at ambient temp, then all we need is to add the density of one more atmosphere to equal what i have seen on a street/race engine. given that NOS is very cold, the question becomes, is it cold enough at injection, to give the extra density. answer is, YES. (in theory)

Implying there is just not enough room in the combustion chamber or in a stroke to do this , is just plane silly.

mk

 

Great POINT! I forgot about the airport that they were doing this with.

There we go, greater acceleration requires much greater HP. You need the hp to accelerate in that amount of distance. Im sure brett has calcuated this well.
1000hp here we come!! gosh, in 2 miles, he might even need more than that!!
I seemed to remember a stopping discussion too.

mk

 

Mark--

I'll rain some physics on our parade. peee-veee-equals-ennn-are-teee. The units are absolute. Your manifold pressure will be atmospheric higherst if the throttle is open, no matter how "cold" the intake charge is, right? The NOS drops the temp by 70f (your number...), multiply by 5/9 and subtract (460+32) from both numbers and you can calculate the change in density by percent, right? NOS has 50% more oxygen by mass, so let's work around the idea of 150f ambient intake manifold air (will probably be less), cooled to 80f by the NOS charge. That's a 7% (seven percent) increase in density. Do the math and see if I'm wrong. I'm thinking that it's not quite possible, with the limitation of atmospheric pressure as max available while the throttle is open, to get 1000hp out of this engine on NOS.

Your analogy to the various pressurized intake systems does not apply. The charge density increases in turbo and supercharger systems are significantly higher than what you can attain with a throttle open to atmosphere.


That's my amateur guess.

 

Give up Bob. Mark isn't going to let math or physics get in the way of any argument.

These guys are talking about making more than four times the non-nitrous horsepower in the stock 928 engine. Here's a video showing nitrous use on a stock car.

http://youtube.com/watch?v=8Kwd41bx4uo

The final power produced is less than double what the car did without the nitrous, and yet it looks like something interesting is happening if you look closely at the air intake opening when the 150hp nitrous run is done.

 

Hi Mark

All correct above, and the "stopping discussion" was about me using a 12 ft Stroud X-chute to slow me down..FAST if needed ...OR if it all goes REALLY PEAR SHAPED...pulling a chute will straighten up a car rapidly...lol

All the best Brett

 

Bob,

Yes, i overstated the density on the tempurature change. plugging the numbers in to near -50F, the density still only goes to 33%. that is not the point.
However, the density of NOS at room tempurature is 50% more than air and if it contains 50% more 02, then there is at least double the HP potential (assuming no other changes)

So, how can the density go up even though the tempurature is much colder? Well, you are right, its not from the tempurature alone, however, i does have to do with the density of NOS in a liquid vapor state. If you have nossils right at the intake ports so that there is atmospheric pressure pushing it in to the decending piston, all of what ever is sprayed out will get pushed right into the cylinder. The question becomes, is the NOS in liquid vapor state when it is sprayed into the intake, or is it just a cold gas. If it is just a cold gas, then yes, the max theoretical potential might only be a factor of 2.33:1 increase in base HP. however, if the NOS can be sprayed in a liquid vapor state, at tempuratures near its critical point, it could be 3x the density of air in total, plus the 50% greater O2 content. so, 300hp x 3 = 900 x 1.5 and there is your 1350hp as a max potential of HP.

Does any of this jive with the physics parade going on here?

Mk