First time on a Dyno

Mark,
Engined bored .020, Hall HP2 cam, Edlebrock Performer and Holley 700. The machinist building the engine (2000 miles ago) thought we would get better than 400 flywheel HP. If I'm losing 20% thru the ZF I still should have about 320 rear wheels horsepower.

Add roughly 60-70 horses for flywheel power; so you have nearly 300 horses from 351 cubic inches, which is a perfectly fine street engine. The low-end is quite high and might come from an advanced cam or other special internal work. What it means is, you'll walk away from all 'Vettes and most other Panteras in a roll-on contest, while still retaining 150+ mph top-end.Congratulations on your motor- don't screw around with it!

you could always add a small shot of nitrous for a liite more kick. s small plate system is more than sufficent75 to 150 shot.

FWIW,

PCNC has had a few dyno days over the past 10 years. We have found that bone-stock low-compression L-model cars put out about 230 rear wheel horsepower, plus or minus a few. With a Holley and Edelbrock Performer intake, power went up closer to 240-245. Headers added another 10 hp or so.

It sounds like your motor is far from optimized. The basic ingredients are all there--now it's down to tuning. You could spend years screwing around in back alleys, changing this and that and evaluating with the seat of your pants.

But since you have access to a dyno, I suggest you fully instrument the car (measuring various parameters with a Sun engine analyzer, and an O2 sensor up the tailpipe) and then see why it's not performing as it should be. It could simply be a timing issue, or incorrect carburetion. It may take a full day of running, changing, running again, but typically a car will drive away from a day like this with another 20-30 hp under the hood, sometimes more.

To me, that's money well spent!

Mike (265 rear wheel hp on a Dynojet, and my 650 dp went way way lean at high rpm. So, a new fuel pump, fuel pressure regulator, 700 Holley, complete MSD ignition, and now I'm ready to establish a new baseline and then begin tuning....)

Thanks to everyone and a special thank you to Mike Drew.
I'm not saying the dyno numbers are wrong, but several car people I know cannot understand how the correlation between the 415 lbs of torque and the 230 rearwheel horsepower. I will take your advice and work with my dyno people. The car is going out today for upholstery and will be gone 2 weeks. If you drove the car you too would doubt the hp figures given me.
Thanks
Lar

>At 4800 rpm the car showed 232 rear wheel horsepower and 415 lbs torque.

It's easy enough to check since (horse)power is the rate of producing
torque. The governing equations is:

HP = (TQ*2.0*PI*RPM)/33000

where:

TQ = torque in ft-lbs
HP = power in horsepower
RPM = engine speed in revolutions per minute
PI = the mathematical constant PI (approximately 3.141592654)
Note: 33000 = conversion factor (550 ft-lbs/sec * 60 sec/min)

Plugging in numbers for 4800 RPM and 415 ft-lbs of torque:

HP = (415*2*PI*4800)/33000
= 379.3

That doesn't match the number you were provided, so someone has made
a mistake. In general, the torque and power peaks do not occur
simultaneously. Typically peak torque will occur at a lower RPM
than peak HP will.

Dan Jones

Dan Jones-
Thanks for your assistance. I knew there was a mistake somewhere. You figure makes everything make sense.
Lar

quote:

---

Originally posted by old and slow:
Dan Jones-
Thanks for your assistance. I knew there was a mistake somewhere. You figure makes everything make sense.
Lar

---

For what it is worth, I just dyno'd my 351C on an engine dyno. A carb change alone made over 100 HP. So, there is HP to be gained cheap on the dyno. My first carb was way too rich. The dyno saved weeks of pain in the arse testing.

It is quite possible the car made 415 tq, but at different (much lower likely) RPM.

The "reduced" HP and TQ equation is...

HP = (TQ x RPM) / 5,252

So, you can say the value of HP and TQ is always equal at 5,252 RPM. And the value of HP is always lower than TQ below 5,252 RPM and higher than TQ above 5,252 RPM.

-Steve

I too have had my car on a Dyno and I was kinda puzzled by the results. However looking at what the stock numbers are maybe I am doing ok.

Here are the main details, my car has a Coast High Performance 377C stroker kit (installed by the previous owner) and a Holley 750 DP carb (installed by me with the help of my wife's uncle who owns his own shop building hot rods in North Carolina). I'm trying to figure out the cam that was used and some other info that the previous owner did but that seems to be the major changes that have been made. As far as I know the heads are in stock trim and I believe are 4v but I could be wrong.

I took the car to the dyno back in August on a very sticky 97 degree day. After my three runs I wound up with a best of 318 HP and 322 Torque. As I said I was alittle disapointed as my wifes uncle still tells me that the car is putting 400+ to the pavement. I trust his opinion as he has been around alot of high horsepower cars however I also don't see how this dyno could be wrong. I mean aren't these pretty accurate?

The plan at the moment is to find another dyno locally to compare with and then we'll see what is what.

Don't get me wrong I know that I am close to 100 HP over a stock motor... but it would be nice to have that 400 show up on a dyno sheet. Considering my current setup, is this unrealistic thinking?

Scott
#1523

Mike Drew, have you dyno'd your car again and what are your mods? (including headers, exhaust) Thanks, Carter

Mike Drew, have you dyno'd your car again and what are your mods? (including headers, exhaust)

>>>HAHAHAHAHA!!! Obviously Carter doesn't know me very well! My car has spent most of its life on jackstands (figuratively if not literally). It currently has no alternator, which means it has no water pump. I can start it, back it out of the garage and that's about it.

I will soon be installing a new alternator along with a flat firewall kit, and then I'll be running out of excuses. :>) I have a blown-out exhaust header-to-head gasket to replace, and the timing is probably out of whack. But once those issues are sorted, I'll be heading to a dyno facility to try to dial it in.

It's basically a .030 over 351C with TRW forged flat-top pistons, stainless valve and roller rocker-equipped open-chamber heads, Comp Cams 282H cam (I think that's the one--it's a pretty stout hydraulic cam from Comp Cams anyway), Ford Power Parts intake (sadly, purchased before they started making specific models for the Pantera which allow engine screen retention), topped with one of Larry Stock's custom Holley 700 double-pumper carbs. Exhaust is factory GT5 (often mistakenly referred to as GTS.)

This engine once generated 389 hp and 380 ft/lbs on an engine dyno, with an unknown ignition and unknown carb. So it made power once upon a time, but nothing earth-shattering.

Time will tell if my recent changes (also installed a new MSD ignition) will improve things any.

Cheers!

Mike