Ken look at this please...dyno

[johnny]

It is almost done, the new sequential DTA computer installing on my 86 vette. This is unique.

The attachment shows the dynorun with the last mod a have made:

tpis headers, B&B tri-flow 2,5" exhaust, adjustble fuelpressure regulator, edelbrock performer heads, no kats, on EGR, LPE SuperRam + baseplate. I have a zf-6 speed too.

The next will be:

no cruise controle and no airco, dta computer installed and 1.5 ratio roller rockers gold series, race airfilter and maby my new Holly 58mm billet TB!

 

[Ken]

 

[rrubel]

Holy $(^$%!!! 414 lb-ft of torque? Two quick things...

1. How hard was the 6-speed install?
2. I thought torque and HP were always equal at 5250 RPM. They're definitely not on this graph. What's up with that?
[RICHR]

 

[johnny]

Holy $(^$%!!! 414 lb-ft of torque? Two quick things...

1. How hard was the 6-speed install?
2. I thought torque and HP were always equal at 5250 RPM. They're definitely not on this graph. What's up with that?
[RICHR]

Richard,

No the torque is not 414 lb/ft, you have to convert it, it is 414 Nm, witch is 305 lb/ft, witch is 396 lb/ft at the flywheel. Maby later, maby later...

Why should torque and hp always equals at 5250 rpm? Is there a reason why?

I bought the 86 vette with a zf-6, as far I know they have swaped the whole thing, include the engine. So I was lucky...But I have heard is swapping the zf-6 is one week work.

 

[rrubel]

Why should torque and hp always equals at 5250 rpm? Is there a reason why?

Simple - the formula for torque is

TORQUE = HP * 5252
__________ RPM

Therefore, when RPM = 5252, HP and torque HAVE to be equal. No debate. For more info, see the page Power Primer. Yes, it's at a competing site, but it's a decent read. Sorry for the underscores, but I couldn't get "RPM" to line up right.

And yes, I said 5250 instead of 5252... old age does that to you

Even trying to convert from NM to ft-lb, I still can't get things to agree, unless your HP is not SAE.

[RICHR]

 

[johnny]

Rubel,

I have heard something like that, I dragrace guy told me once that the US hp are a little bit different of European hp. What or how much I do not know. I will try to find out and I let you know.

here is another one, my firts dyno run, only with Borla mufflers.

 

[johnny]

· Conversions
kg = pounds / 2.204
km/h = mph / 1.609
kW = bhp * 0.746 (or PS * 0.736)
litre = imp. gall * 4.546 (or US gall * 3.637)
· The following relationship exists between EC and DIN HP ratings:
1 HP (EC 95/1) » 1.015 HP (DIN)
A suitable conversion for SAE HP is not known, though the following relationship is believed to exist:
1 HP (EC) > 1 HP (DIN) > 1 HP (SAE)
i.e. SAE power and torque numbers are larger than DIN, which are larger than EC.
The characteristics of the DIN and EC standards are:
· DIN 70020 (TBC) = 1013 hPa pressure and 20°C temperature.
· EC 95/1 = 990 hPa dry pressure and 25°C temperature.
(dry pressure is calculated as normal pressure less humidity)
· Values for the drag coefficient (cd) and the cross-sectional area (a) determine the aerodynamic resistance to motion (Ra), according to the formula:
Ra = k * cd * a * v2
where k is function of air density. Empirical values for cd range from 0.24 race/prone to 0.39 road/upright, and a from 0.4 race/prone to 0.9 road/upright. In all cases, I've omitted k,
set a=1, and varied cd to make the resistance curve (Rtotal) cross the net tractive effort curve at the measured to speed.
For these spreadsheets, the values of the individual parameters to Ra are unimportant, as long as they result in values for Rtotal that meet the cadence tractive effort at the
measured top speed.
Rtotal > TE – implies overdrive
Rtotal < TE – implies under-gearing
The net Tractive Effort (TE) accounts for all of the rotating transmission losses, therefore Rtotal is the sum of the retarding forces, i.e. air resistance (Ra) and gradient resistance
(Rg).
· It is known that the rolling resistance due to the tyres is an exponential function of speed. However, tyres are designed so that this resistance doesn't start to ramp up within the
designated speed rating of the tyre. Under this constraint, it approximates to a (small) constant, and is not incorporated into the calculations.
· Mass of fuel is 0.7 kg/lit
· Mass of oils (fork and engine oil) is 0.9 kg/lit (guessed – heavier than fuel, but lighter than water)
· Gear-change time is guessed. Having sampled both the Sprint ST and the 996, the 996 is definitely slicker.
· Mass of accessories is guessed.

 

[johnny]

So, I will see if I can convert too SAE standards, de DYnojets uses normally SAE, but maby the tuner has set the numbers on DIN or EC. I have heared talking about it, but now I understand the difference. Okay, I'll ask.

 

[johnny]

correction to SAE??

I have searched the www for expanations, so far as I think it would be this.

The dyno shows rearwheel power in Nm and in DIN, so to covert to SAE should be this.

414,1 Nm rwhp = 80% = 517,6 Nm at the flywheel
252,8 hp rwhp = 80% = 316,6 hp at the flywheel

517,6 Nm = 382 lb/ft DIN

SAE = add 10 till 15%

360 HP and 430 lb/ft SAE at the flywheel???

 

[johnny]

real horsepower

Today I had a little chat with my engine tuner, who actually tested my corvette on the dyno. He said:'We do not add any conversion programs to our testing, no DIN, SAE or CEC, the Dyno gives the actually real horsepower on that particial moment, it is a matter of physics. What your car has is what you got, also we have a single rol dyno, wich means that the difference in tyres could be forgotten.'

also he said: " the only thing to compare cars, is to test them at the same time, same day, but on the other hand, the difference would be minor when tested on another day."

and:" What you realy got on the engine is only too test on a enginedynostand, the rest is guessing, I say between 15 til 20 percent friction loss."

So what really counts, is what you actually put on the road compare too the weight it has to move. So my vette has still 253hp and 305 lb/ft.