Hey

A local shop that has just opened had a Dyno day today , so i decided to enter . There were a few cars so the bloke was trying to go through them as quick as possible .
Anyway on the graph below i dont understand why my torque curve is complete opposite to my HP curve ?, I would have thought when the engine was producing max HP it would be producing max torque ??? not the opposite . Also i thought you need to know the rpm to work out torque ? ( not on graph )
Does this graph look right to you ....? I also noticed tyre smoke and could here the wheels squeeling ( slipping ) could this have affected the torque curve and maybe the HP ??

General Engine Details :
355ci
ik200 Brodix Heads
full roller rockers
Brodix HV1016 intake
Hypertechnic Pistons
engine parts balanced
1"3/4 heddman headers
670 holley street avenger
110gph mech holley fuel pump
CompCam 284H
MSD 6AL ignition
th350 Auto
10 bolt diff 3:08 ratio


Thanks Downesy

chart looks fine what was the max torque/hp? and at what rpm? power looks to be way low for your listed parts whats your compression?

Slippage would cause a loss of power to the rollers so yes, smoke will affect the readings. The chassis dyno measures the acceleration rate of the roller. The calcuations are not dependent on how the operators formats the output of the graph. It is normal for torque to fall as shown on your graph. The torque peak is never going to line up with the HP peak. Your RPM where HP and torque cross is 5252, which is right about at 108 km/h. HP=(TQ*RPM)/5252.

Your readings seem WAY low for the parts listed. If you are at about 10:1 compression I would est. you should be right around 350-375HP at the wheel with the cam and heads combo.

What is your compression at?

Also, if your wheels did slip, just throw that graph away as it will be completely off. How did they tie down your car?

If you know the tire radius and overall drivetrain gearing, you can find the RPM of the engine, and make a graph of power and torque vs RPM. I have no idea why they didn't do that for you on the printout, because the graph they gave you is not very useful.

I hate when they map against MPH instead of engine RPM. Makes the results almost meaningless. That printout looks similar to a Mustang Dyno. If it is, the HP numbers are always lower than the same car run on a DynoJet. My brother's mildly worked and injected 400 in his old GTA only put 250HP to the rollers on a Mustang dyno but would pull that pig-heavy cruiser (3900 lbs. race weight with driver) through the traps at just shy of 111 MPH. A lot faster than only 250HP would indicate.

As Rick mentioned, torque (in ft/lbs) equals horsepower at 5252 rpm. If a dyno graph does not show that then somebody fudged the numbers.

When the graph uses two different scales, like yours does, it can make it a little confusing. I saw that your torque reading is in Newton meters, but horsepower was used. I know Europe uses Newtons, but not horsepower. I don't know any of the conversions.

It does look like you had some traction problems starting around 120 km/h. However, the torque curve doesn't seem to drop off at that point, so I'm not sure.
Your cam will probably produce peak torque somewhere around 2500 rpm.
Horsepower=torque*rpm/5252. The further apart the torque and horsepower peaks are the wider your powerband is, and the more usable power you (typically) have.

Im not completely sure of the compression ratio i would be guessing probably 10;1 with those pistons and 200cc heads, even if it was only 9;1 the engine has only done 8000 miles . I agree ,whats with the graph in km/h NM and HP , he should have at least added the rpm for me . I was hoping for 250 - 260 Hp at the wheels does that sound unrealistic to any of you ? or is there something wrong with the engine?, or just his dyno graph and the way he did the run ? , it goes hard on the road ? . the car was held down buy staps to the diff

You should be 350-375 rwhp

Have you ever run it at the track that would tell more

Yeh there is no local track here , that would tell more . I just run my setup in desktop dyno and come up with 398hp at 6000rpm if that is even close , how could i be losing over 190HP through the drive train to the wheels !

What's it run through the traps in the 1/4 and what's it weigh? That'll give you a better basis to back-calculate the horsepower to a relevant number.