berlinetta85383

I though it would be kinda cool if we started a post on the horsepower people have put down to the wheels, the type of dyno that was used (mustang or dynojet) and the track times and mph that people ran. Elevation and vehicle weight could also be chucked in there, since they both serve a purpose. I only managed to put down 278 hp at the wheels on a mustang dyno and close to 300 ft lbs of torque. I ran a 12.87@107.2 at 2800 feet uncorrected. I was dissapointed with the numbers at first but I have heard of anywhere from 20-35% drivetrain loss in hp.

paul_huryk

While I never dyno'd my car, I'm sure that the numbers are lower than expected. But 1/4 mile performance is all about average power over the RPM range, not peak hp - this is why the quad 4 was a dog even though it had the hp of an 8 cylinder.

berlinetta85383

Some tables/pics of peoples dyno runs would be pretty cool. post away people

25thmustang

I have these to work with...

221 rwhp
276 rwtq
13.89 @ 98

xxx rwhp
xxx rwtq
13.05 @ 103

272 rwhp
316 rwtq
12.79 @ 105

Ill have new numbers tomorrow for the 1/4, hoping for a mid 12. Car has stock bottem end, stock cam, stock heads, cobra intake, all the bolt ons!

TTA 1387

Only dynoed the TTA once when it was still running all the stock stuff.

318rwhp
455rwtq

Times at that time were 12.15@111.09 with a 1.69 short time. Track was MIR and elevation is around 0-100'.

The only other car I had dynoed was my 96 WS6. 4.10 6spd car.

274rwhp
305rwtq

Ran 13.18@104.9 on a 1.87 short time.

324rwhp
324rwtq

Ran a 12.44@111.4 on a 1.75 short time.

Hope that helps.

jms

iTrader: (1)

14.02 @ 99.6 mph---2.0 60 ft on Pep Boy Futura tires

224 hp at 4500 rpm and 298 lbs torque at 3000 to 3500 rpm (later run at 302 lbs torque) on a dynojet.

1988 GTA 5.7, stock cam, three-angle valve job on stock heads, pocket-ported, stock injectors, cold-air induction (home-made, which would show no difference on the dyno).

1.6 roller-tip rockers, stock TPI with the "free-mods", SLP 1-3/4" headers (no difference on track from Edelbrock headers), 3.27 posi-rear, 3/4 tank of gas and my lard rump (200+ pounds).

Basically very close to stock.

Ate my fair share of LT1s at the track. Auto Lt1s were easy, 6-speed versions depended on the driver.

Now the tranny has some issues on 2-3 shifts after a couple of runs.

Also seen near 30 mpg on several occassions and have surpassed it a time or two.

jms

AlkyIROC

Never had my car on a dyno. I don't race dyno times. All my numbers are from power to weight ratio calculations based on MPH and vehicle race weight.

A 300 hp 3200 pound car will mph faster than a 300 hp 3500 pound car. Gearing in the tranny and diff plus rear tire height will determine how each will ET.

You can change your chassis dyno numbers be simply changing the driveline. Without doing anything to the engine you can increase RWHP by swapping out the 700R4 for a TH350 or better still a powerglide. The 10 bolt has the lowest hp loss because of it's smaller size and mass. You'll lose hp by going to a 12 bolt and lose even more by using a 9" however both can take more hp than the 10 bolt. Pumping up the air in the front tires reduces rolling resistance. Having a very wide rear tire increases rolling resistance.

The percentage loss through the driveline is a poor way of doing calculations. If your engine produces 400 hp and you estimate a 20% loss that means you're only using 320 hp. Now swap in a powerglide and you have more available hp without touching the engine. Since the PG only requires 18 hp you now only have roughly a 5% loss. Even doing internal modifications to 3 or 4 speed auto can reduce the amount off loss.

If you really want to know exactly how much your drivetrain eats up hp you need to have the car on a chassis dyno and have the engine on an engine dyno and compare the 2 numbers.

HP required to operate tranny
Powerglide = 18hp
TH350 = 36hp
TH400 = 44 hp

Doing tranny swaps can also change the weight of the car. A bulletproof TH400 is 130 lb while a race ready PG is only 97 pounds.

xpndbl3

iTrader: (5)

so essentially a trans-brake'd TH400 only uses up 12 more HP than a TH350 all things being equal? not to mention they can handle a lot more abuse and take the same convertors....?

AlkyIROC

That's why you won't see many TH400's in Stock Eliminator, Super Stock or Comp Eliminator. Most use TH350, metric 200's, 200-4R or powerglides just because of the decreased power loss through the tranny. It just costs more to get lots of HP through the tranny without it failing.

My powerglide uses the same torque converter that I had on my TH400. You just need to buy an aftermarket hardened input shaft with turbo splines..

smithtc

iTrader: (5)

Can you provide some data proving this? or...further explaining this statement?

Chevy HP magazine just had an article concerning shift points, and found that to shift out of your current gear at the same horsepower level that you enter into the next gear provided the best elapsed times (differences were minimal, however). My interpretation is this goes against the "Average" hp under the curve.

AlkyIROC

Camshafts all have a power bands. Most are in a 2000-2500 rpm range. If you shift at 6000 rpm, you should be starting the next gear around 4000 rpm to stay in the powerband.

A street cam has a very wide powerband because it has to deal with all type of driving. A race cam has a very tight powerband because it's only used at WOT for a short period of time. A wide powerband isn't good for drag racing because you don't have enough time to go through the entire powerband in each gear during the 1/4 mile.

HP means nothing without torque. Many of the new cars with small engines can brag about high hp numbers but they don't have the torque to back it up like a big V8. 2 engines with the same amount of HP but one produces more torque will be faster. Also these small engines produce maximum hp usually at an rpm range you'll never get to during normal driving.

smithtc

iTrader: (5)

I understand the torque-hp relationship. I was talking about 1/4 mile performance...not normal driving...and the fact that the hp numbers is what you want, not average. I haven't seen many talk about it in detail. But, that's ok.

Apeiron

Imagine two cars, one makes 350 HP @ 3000 RPM and 400 HP @ 6000 RPM, and the other makes 200 HP @ 3000 RPM and 425 HP @ 6000 RPM. Even though the second car makes 25 more peak HP, it takes longer to accelerate to 6000 RPM, so it's the slower car. The first car has a better average power over the whole range than the second.

smithtc

iTrader: (5)

Can you prove it with more information than what you provided in your statement?
If it has a peak of 425, and you are able to avoid valve float, and bridge beneath the hp peak with your gear shift points to where you have a higher hp number at that point than the 1st vehicle...you will accelerate faster. If I interpret the article correctly.
Every detailed analysis I have seen of late argues against some commonly preached themes. I'll see if I can find one other than the chevy high performance article I mentioned.

AlkyIROC

http://www.hardtail.com/techtips/hpandtorque.html

Blu91Z28

Sig, Dynojet

Apeiron

It's not a question of having more horsepower at the shift points, it's a matter of having more area beneath the curve.

Apeiron

Here's a graph of the HP curves of the two hypothetical cars:

<img src="http://members.shaw.ca/crussel/graph.gif">

25thmustang

Car 2 is gonna be boring, car 1 is going to be fun to drive...

AlkyIROC

But on a dragstrip I'd rather have car 2 even if car one made more HP.

25thmustang

Really Id rather have car 1, at th track you spend time at RPMs ranging from 5000-6500 in that car. I would rather have the hp at 375+ for that time, then from 320 to 420... especially if it makes more power!

camarojoe

The engine comparo with the two hp curves is a neat example, but with our cars and 350+ci motors it is very unrealistic. Small blocks make so much low end tq that the hp curve of car 2 seems too unbelievable to be compared. Now if you're comparing a turbo engine to a 350 then it makes more sense.

pasky

Dyno's really don't mean jack. I had a buddy who dynoed his 96 LT1 camaro. The thing only Dynoed 256 rwhp on a dynojet, he had headers, CAI, exhaust, cut out, basically all the bolt ons. He takes it to the track it does 12.8. Hows that for ya? Not all dyno's are created equal.

25thmustang

I agree 100%, my dad made 272 rwhp, yet pulled 12.3 @ 110!

paul_huryk

Lingenfelter proved the therory with the superram vs LT1 intake trials he did. Both cars made the same peak hp, but the superram car made a lot more mid-range torque. The superram car accelerated faster in all trials and even got better fuel economy. I have to search for the article. That is all about power under the curve.

One thing I think is relevant is to compare computed hp based on et and mph compared to dyno'd hp data. I'm sure you will find that a tq monster like a big-block or GN/TTA will dyno a lot lower hp than you would think, but will turn in impressive times. Conversely, a high rpm small motor will do the opposite.