Chassis dyno results.. not what you might expect

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Chassis dyno results.. not what you might expect

Postby XXXXXXXX » Thu Jun 01, 2017 2:33 am

How accurate are chassis dynos? I don't have much experience with them and today was the first time I have taken my car to one.
I know many factors can effect results.. temps / combos / convertors / transmissions / gears etc etc.
But I took my truck to a chassis dyno today to do some tuning and the results are not what i expected at all.

So first off been in classic car game 25+ years.. don't know everything but smarter than many for sure.
I had a 9 sec street car.. solid roller small block.. afr heads.. pump gas went 11.4 on the motor in a 4200lbs car. 9 sec on minor spray blah blah...

So my s10 2980lbs (3240 with me in it) stock lb9 305.. 3000 stall.. 700r4.. 3.42 posi.. mini blower..
The engine is a mystery as it came in the truck but it has no lope at idle.. block number decodes to lb9 305.. heads are 801 1.72 intake heads..
so the engine is basically an nothing burger.. added the 144 blower.. thing runs like a raped ape for what it is.. in fact when driving it feels like 4.
a very well built small block and sometimes under boost (when it was cooler) it reminded me of my how my monte carlo felt on motor..
thing pulls awesome and is fun.

Now to the chassis dyno today.. strapped it down and did 4 pulls ... all 4 pulls were pretty close.. but the peak or highest number were... wait for it!!!!
194 rwhp and 210ft lbs tq...

The numbers just don't seem right... this isn't "sour grapes" on my part.. it just doesn't seem like its making that little.. its way too much fun to drive.

My truck weighs 2980... 3240lbs with me in it and 1/4 tank of gas.. if you use this calculator
and put 3240 and 194.. it says 14.9 and 91mph.. my truck is way faster than that... most s10's that do a bone stock 305 swap can do those numbers.
Mini blowers usually add 80-100hp bolt on to a stock engine... so what I had a 100hp 305?? LOL..

So how accurate are chassis dyno's? If they strap it down to tight can that effect hp numbers? Can a "calibration" in the computer set up make it off?
Just cant figure out why the numbers are so low..

Opinions or experiences welcome.

Thanks X
82 S10 Longbed.. stock 305.. b&m 144 blower.. 7lbs.. stock 801 heads.. dyno'd 194rwhp...holley 750dp.. percys adjust a jet in the front & rear.. headman 1 1/2 shorty headers.. 2 1/4 dual exhaust with hooker aero chambers.. msd with boost timing master.. 2500 stall .. 700r4 .. 3.73 posi fact s10 disc brake rear end.. caltracs.. 275/60/15 Nitto Extreme 555 drag radials
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Re: Chassis dyno results.. not what you might expect

Postby lowblazin94 » Thu Jun 01, 2017 8:03 am

Yes depends on dyno etc.

But that is power to the wheels. Crank hp could be more around 250 or so. The torque is what makes these things move and it doesn't take much for these trucks to love it.

Dynos are good for tuning but take it to the track and see how it does, thats the real judge.
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Re: Chassis dyno results.. not what you might expect

Postby bgblock427 » Thu Jun 01, 2017 1:28 pm

should be around 230 at the crank, those heads are holding that engine back, its fun to drive cause its all low end torque that can be felt. A 1.94 valve head woud add some better flow, cant go any larger cause of bore size and valve shrouding.
think of this that little 1.72 valve is like a restriction to air flow even though you are pressureizing the intake charge with the 144.
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