ne14a6t9

I agree, 400 hp through a t400 unlocked and If I remember correctly this car has a 12bolt and 4.10's, that is good power, curves look great I was thinking around 430- 435 if It had a locked verter and 4l60e, around were JS is in his car, seems to run similar

02BlackWS6

Screw the dyno, it doesn't really mean squat. You only need the dyno to get your A/F tuned in. Your ET and MPH show that Jay did a great job and that you have a fast car..period. Don't fall for the dyno number BS. Nice car. Take care.

Terry Burger

iTrader: (4)

No, but its safe to say it can make 400rwhp!

Aidan

Actually i think the problem is your using a junk calculator.

Prestages calculator is WAYYYY off. Ive done alot of testing on different online calculators..and after running countless fwd/rwd cars through several of them, the only online one that has came out acurately is www.smokemup.com "HP from 1/4 mph"

Running it through the calculator there shows 3350 & 122mph= 413 rwhp, 121 mph = 403 rwhp.

Id say your cold air kit etc gives you a hair more power going down the track



Any calculator that tries to calc ET is not accurate as theres too many variables to calculate.

Such as a 300 rwhp n/a car with 100 shot nitrous (400 rwhp) will run WAY faster ET's than a 400 rwhp all motor car. and a small block 350 cube 400 rwhp motor will usually run slower than a 454 bigblock 400 rwhp motor at equal weights...so 1/4 calculating is a waste of time. only mph is accurate from calculators.

critter

iTrader: (9)

Oh no, Chris - not you!

Yeah, f=ma and all that jazz. I know the drill; I do it with EFIlive and LS1M. And, if you choose to define the output of the Dynojet computer as reality, there is no argument.

However, in the real world, things aren't as neat as the equations make it appear. Differentiation is inherently noisy, or amplifies noise. This requires filtering, which has an inherent time shift, which skews the results. This has the effect of moving the HP peak up in RPM as the filter corner frequency drops. In the analog world, this is the phase delay introduced by the filter. In addition, real events can get masked by the filtering.

As you note, the dv/dt of the drum can be used to calcualte a power number, given the constraints above, but the power number is that absorbed by the drum. The question at hand is dyno numbers vs track times. Different gear ratios produce different HP numbers on a Dynojet, as do different tires sizes, different rear wheels, different driveshafts, different flywheels, ad nauseum. Which gear you dyno in makes a difference, and the difference is greater than you would expect from the difference in gear to gear transmission loss.

The result of this is that on a given car, you should find reasonable correlation between Dynojet numbers and track performance as long as none of the things mentioned above are changed. That is, mixture ratio change should correlate well, but I would not expect the loss the Dynojet reports going from 3.42 to 4.10 gears to show up as performance loss at the strip.
I am confident that you would be hard pressed to find good correlation between Dynojet numbers and track performance across a sample of cars. I've tried

critter

iTrader: (9)

All of those are likely based on the old (and I do mean old) equation:

HP = weight * (MPH / K)^3

where K = 235. I don't think that is a good value for the constant today. For insance, using ChrisB's numbers, the constant should be 252, which I find to be closer to correct for RWHP numbers from MPH. Using 252 produces more reasonable numbers for Reckless also.

That's a fact, Jack! Going the other direction, HP -> ET, only gives you an indication of what you might do with all things right.

Reckless

iTrader: (9)

Good post Aidan, and thanks for that site. What the car makes on the dyno is not a big deal. I just thought it interesting since my car is not a "dyno queen" and runs well.

The cam is a new Comp Grind for this year, and I bought it through my local speed shop. The grind is an X-ER and the specs are 232/234 .595/.598 112.

The heads are very nicely done by Jay at Absolute Speed. 5.3L castings with no milling. Typical stage 2 head. He never told me valve sizes or anything like that, so maybe he will chime in. I do know they flow 306 @ .600 on the bench

I built the motor in my garage. Had the internals balanced locally. Eagle rods and Wiseco pistons with 2cc reliefs. Runs about 10.8:1 CR.

Bowtieman4life

iTrader: (1)

439 RWTQ is the reason your car runs so fast. Remember, HP is fun but TQ gets it done.

JS

iTrader: (4)

Actuall Dennis MPH indicates HP and if the car puts down big dyno numbers and its setup for the track it should run these kinds of MPH's.

I say if he put the setup behind a locked A4 it would should 440RWHP,Just about where I'm at now.

Very impressives setup bro...

mikemodano9c

all his upgrades to strengthen the drivetrain take power. the tranny and rearend do eat power, but everyone seems to be missing the point of what i thought the original post was about...the car's power output...

it makes 400rw...of course it would make more in either an m6 or a locked 4l60e with a 10 bolt and 3.42's...

IT MAKES 400RW...END OF STORY

IT RUNS GOOD!

i like that cam...my cam is a comp "off the shelf"...its not one of the x-er cams its a xtreme energy high rpm (woot)...i would have liked that cam your running reckless but i didnt wanna run 918's because of the lift and i was to cheap for dual springs...

Reckless

iTrader: (9)

I used the Crane dual springs since they didn't require any machining.

ChrisB

Carl:

But your points support the argument that the dynojet isn't perfect - not that there isn't a correlation (between what the dynojet measures and actual horsepower). I will be the first to agree that power produced as the dynojet measures it isn't neccecarily the same as power produced going down the track - but is it analgous? In my experience, yes. I have always had good luck with dynojet vs. track correlation (when weight, weather, etc. was taken into account).

And of course gearing, changing rotating mass, etc. will effect the output of a dynojet slightly - you have just changed either the inertial mass of rotating components (light items), or the rate at which all those components have to accelerate (different gears).

I am definitely not purporting that it is a perfect machine, etc. - but I do disagree with the notion that there is no correlation.

critter

iTrader: (9)

I don't know what you define as "actual horsepower". Flywheel HP? Mustang HP? SAE HP? Dynojet HP? Theoretical HP?
I think we have acheived middle ground
I suppose by definition they are analogous ("similar in certain respects") in that, in general, on any given car, an increase in Dynojet numbers should translate into lower ET and greater MPH at the strip. The major exception is the rear end ratio. Perhaps you could apply analagous to a cross section of cars - not sure on that. What I said was that there should be resaonable correlation on a given car given some caveats, but that I am confident you won't find good correlation across a bunch of cars.

I'd love to see a study that shows correlation across a bunch of cars, so please share if you have it. I looked and couldn't find it. That is what led me to examine today's dynos. I had never heard of inertial dynos, although I was quite familiar with the priciples. (remember, I have been away from the game for a long time). Back in the day, dynos, both engine and chassis, were absortion - water brake, eddy current, even some oil. We even made a bike dyno with a hefty disk and caliper. All those measure torque and aren't bothered by the things that change the readings on an inertial dyno (like Dynojet, among others). I concluded that the major thing inertial dynos had going for them was cost. All chassis dynos have roller, etc, but the inertial only needs an RPM transducer and a computer. An absorption dyno needs a load cell, an absorption unit, means of disposing of the heat generated, etc - all more expensive than a simple RPM transducer. In exchange for cost, inertial dynos give up accuracy. Not necessarily a bad tradeoff, as long as you understand what is going on and how to use it.

How sure are you about "slightly"? I don't think I would describe what I've seen as "slightly".

Again, I don't say _no_ correlation, just correlation only under certain conditions

LS1x2

iTrader: (11)

It's the th400 making the dyno numbers lower on the chassis dyno. That is actually the most I have seen from a h/c car with a th400/th350. I know of one car that dynoed 360rwhp and trapped 120+ with a th350.

Scalpel

iTrader: (4)

Yes, that's correct, the TH400, or any setup like that will suck up a LOT of power on a chassis dyno.