GKK

I know 305 tbi Camaros came stock with 170hp but, was that measured at the flywheel or at the rear wheels? I thought the automobile manufacturers measured HP at the rear wheels. I'm trying to get 225hp at the rear wheels. With the mods I have how much HP do you think I have at the Rear Wheels.

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"91" RS, 305 tbi, 5spd, Slp Y-pipe, Random tech Cat, Flowmaster crossflow, Ultimate tbi mods, Edelbrock open element with 3" K&N, Taylor Spiro Pro wires, Redline water wetter, 180* thermostat, Jet-fan switch.

[This message has been edited by GKK (edited November 19, 2001).]

Tas

flywheel. Its a bit on the conservative side by maybe 5-10HP

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-Tas
'89 Formula WS-6

305, TBI, 700R4, P.A.W. 14x3 open element with K&N, Milodon 160* thermo, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips, Hooker 1-5/8" 50 state legal headers, Dynomax 3" I pipe (PN 44063 and 43248)
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brharris27370

TAS is right. For an automatic you usually have 20% lost in the drivetrain so 170 * .8 = 136hp at the rear wheels stock. Most do get a little more than that like TAS said. You are probably running mid 150s. You will most likely have to change heads, cam and intake to get 225 at the rear wheels. That is almost what a stock LT1 puts out.

NJ SPEEDER

actually guys, gm started giving the stated hp as being at the wheels in 1972 to try to fool the insurance co's into thinking the engines were less powerful than they really are. when people dyno their cars and come up with lower numbers it is usually due to the fact that until recently most of the estimates were optimistic to say the least. most cars with engines that have been well cared for will register in the 160's, a little more wear or abuse will lower it since over time rings lose some of their seal, timing chains stretch, and ignition systems heat cycle themselves to the point that they can not attain full charges.

later
tim

------------------
91 Camaro RS-LO3,Auto
New Times Coming Soon!
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GKK

Thanks tim, I was sure the hp figures were measured at the rear wheels. With the mods I've done my car sure doesn't feel like it has only 150hp! I used to own a Supra with a stock intercooled turbo rated at 232hp and my Camaro sure feels close to that.

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"91" RS, 305 tbi, 5spd, Slp Y-pipe, Random tech Cat, Flowmaster crossflow, Ultimate tbi mods, Edelbrock open element with 3" K&N, Taylor Spiro Pro wires, Redline water wetter, 180* thermostat, Jet-fan switch.

Tas

They're not measured at the wheels but they are measured with all the stock restrictions on them (exaust, stock intake, stock air cleaner assembly...). They aren't gross HP like before the 70s with open headers no drivetrain attached etc... Loss from turing the rest of the drivetrain still needs to be considered which is the 10%+ that all cars have. Except with cars like the severly underrated LS1s, the HP at the wheels is almost never the same as the advertiesed HP.

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-Tas
'89 Formula WS-6

305, TBI, 700R4, P.A.W. 14x3 open element with K&N, Milodon 160* thermo, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips, Hooker 1-5/8" 50 state legal headers, Dynomax 3" I pipe (PN 44063 and 43248)
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GKK

I thought back in the early days they measured HP with the engine on a Dyno Stand and these days they put the cars Drive Wheels on the Dyno Rollers to measure the HP. Isn't that the difference? 135-155hp just doesn't feel or sound right even for a 10 year old car.

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"91" RS, 305 tbi, 5spd, Slp Y-pipe, Random tech Cat, Flowmaster crossflow, Ultimate tbi mods, Edelbrock open element with 3" K&N, Taylor Spiro Pro wires, Redline water wetter, 180* thermostat, Jet-fan switch.

Kevin91Z

iTrader: (1)

Wow, are you ever clueless. Some things you're right on, but other things you're way out in left field, like this one.
In 1972, the auto manufacturers started rating the cars with all the accessories and smog equipment on them, that is the net horsepower. Previously they rated engines without that, called the gross horsepower. Crate engines today, like the ZZ4, are still rated as gross horsepower. Engines have never been rated at the wheels, because it'd be different for automatics and manual transmissions. But, companies have always rated engines high or low just because they can, like the LS1 being underrated, or the 99 Cobra being overrated.

Its perfectly normal for a TBI automatic car to dyno at 135 HP at the wheels. That would indicate a tired engine, or some kind of problem, however. My dad's 5-speed RS dynoed at 150 HP and 200 TQ when it was stock.


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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH (2.10 60')
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
-=ICON Motorsports=-

Tas

Thanks Kevin, you said it better than I did. How is that Vortec TPI going? I haven't heard anything yet.
Thanks




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-Tas
'89 Formula WS-6

305, TBI, 700R4, P.A.W. 14x3 open element with K&N, Milodon 160* thermo, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips, Hooker 1-5/8" 50 state legal headers, Dynomax 3" I pipe (PN 44063 and 43248)
Super GRK_Taz World
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Kevin91Z

iTrader: (1)

Its still being built at my dad's shop.

NJ SPEEDER

we are talking about an engine in a stock car nto a crate motor. a zz4 is not comparable in this case.
and the cars are rated at the wheels, just look in issues of hot rod, car craft, car and driver and a number of other mags that have put brand new stock gm vehicles onto dynos and gotten extremely close to the number stated. while the numbers are different for a manual vs. an auto, the estimate of what the power is supposed to be is close.
with or with out accesaries alone on the engien means very little to the power of an engien, an alternator does not take a lot to turn, a power steering pump turns practically free when the car is not turning and a water pump is the least efficant thing on a motor and it is only about 10-15 hp at the crank at worst.
that is not an accurate representation of what the tests saw at the rear wheels, which was near the stated number.
i don't see how a tbi motor could dyno at 135 normally. i went 84.9 mph dead stock, that woudl be in the 160's at the wheels. that sounds awfully near the 170 that the factory states. my car was in perfect condition when i got it. most of the cars that i see going slower or coming up with less power are known to not have been as well cared for.

later
tim



------------------
91 Camaro RS-LO3,Auto
New Times Coming Soon!
Check Out The East Coast F-Body Nationals Home Page
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Tas

lol, how close? Do the math, its 10%+ on most cars. That's the drivetrain loss. If they were measured at the wheels there would be 0% loss.

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-Tas
'89 Formula WS-6

305, TBI, 700R4, P.A.W. 14x3 open element with K&N, Milodon 160* thermo, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips, Hooker 1-5/8" 50 state legal headers, Dynomax 3" I pipe (PN 44063 and 43248)
Super GRK_Taz World
F-Body Dual Exaust
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[This message has been edited by Tas (edited November 26, 2001).]

GKK

Lets say my engine is rated at 170hp at the rear wheels, and taking into consideration the 15% loss through the drive train (25.5hp), would that mean my 305 is putting out 195.5hp at the flywheel? 170hp at the wheels + the loss of hp from the drive train 25.5hp = 195.5 at the flywheel?

Mr. Pibb

yup, but drop the .5 . Rememebr the rules of significant figures. You can only be as accurate as your least accurate number is.


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Mr. Pibb
1991 RSS

I NEED MORE CUP HOLDERS!!!!!

allious

BINGO..THAT'S HOW YOU CALCULATE IT.

NJ SPEEDER

as i stated before they are estimates, and not completely accurate. and if you plan to compensate your drive train loss as only 10% you must be buying some really nice stuff. it takes about 22hp to turn a t-5 and about 34hp to turn a 700r4. to that you would have to add the losses from the rear. that doesn't even compensate for the accesaries. it is an at the wheels number, not an accurate one, but an estimate.
and maybe you shoudl do the math, my car weighed in at about 3500lbs when i went to the track for the first time i went to hte track and ran 84.9 mph. that works out to 166hp at the wheels(mathematically). my car was stock then, all of the restrictions that you are accounting for plus the whoel drive train that you aren't accounting for. does that mena that my drivetrain magically only sapped 4hp? i really doubt it.
i am not sayiong th at the number that gm released is perfectly accurate, just that it is supposed to represent the power at the drive wheels.

later
tim


------------------
91 Camaro RS-LO3,Auto
New Times Coming Soon!
Check Out The East Coast F-Body Nationals Home Page
www.geocities.com/njspeeder
My MAFB.ORG Home Page
www.mycar.net/mafb/registry/detail.cfm?id=299
DSI Racing Home Page
www.geocities.com/foff667

FT-LBS

Factory ratings are at the flywheel with all accessories on, including air conditioning, except in the case of the 99 Cobra when they turned off the A/C and turned on the starter motor...but seriously it is net hp at the flywheel and that’s 170 for a 92 Camaro RS w/ the L03. The reason the Camaro feels as fast as your Supra is because it has 255 Ft-Lbs of torque and the Supra probably has about 210. Torque is what you feel when you step on the gas. Horsepower is a calculation based on torque, RPM, and the standard multiplier.

HP = (TQ x RPM) / 5252

Another factor that makes the Camaro feel so fast is that it is making its torque at 2400 RPM. The Supra engine couldn’t power a small golf cart up a little hill at 2400 RPM. It only gets strong around 4000 RPM and by then, you’re at the next red light.

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1992 Camaro RS 5.0 TBI A/T

Tas

1. They test the engine with the accesories and all the smog equipement.
2. 35hp to drive a 700r4 ay? The z06 is missing 42.7 HP. Sounds like drivetrain loss to me.

Factory rated it has 385HP, 385TQ. It dynoed. 345.9 TQ, 342.3HP

This is from the Aug 2000 Car and Driver. Page 33.

92Camaro305TBI

Mine is rated 153 HP on the dyno! I ran a 10.2 in the 1/8 Major wheel spin. 2.3 i think on the 60ft.
Which if everyone that says I have 20% loss becuase i have AT then I would really have 183HP,

I have modded though.

You all still have to figure that the dyno is calibrated correctly and the people who are doing the pulls are doing it correctly.

A dyno that I know of is when it is ready to run down the track. Engine in the car! Engine in the car is RW HP ? Net? or Gross, Or flywheel???


Maybe thats where im getting confused. What are the definitions for Gross, flywheel, net and RW?

Oh can we put up a definitions page on the site.

Thanks

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92 Camaro 305 TBI Automatic
https://www.thirdgen.org/rides/index...ew&rideid=6100

[This message has been edited by 92Camaro305TBI (edited November 28, 2001).]

Tas

Gross HP is the engine on the dyno stand with as little power inhibiting things on it as possible. No smog, with headers, as few accesories as possible usualy just the water pump and alternator.

Net HP is what cars are rated at. They are tested with all factory smog devices, full exaust, and all the accesories with no transmission. Just the engine on a stand with the above mentioned.

RWHP(rear wheel HP) is the hp that makes the car go. It is measured at the wheels so all the losses turning the driveshaft, transmission, axles, and wheels are taken into account. FWD cars have FWHP. I dunno what you would say and All wheel drive car has. AWDHP? WHP, wheel HP?

flywheel HP is the HP that any engine gives out on a dyno stand. It could be a crate engine or a stock engine. It can also be called crank HP, HP at the crankshaft.

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-Tas
'89 Formula WS-6

305, TBI, 700R4, P.A.W. 14x3 open element with K&N, Milodon 160* thermo, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips, Hooker 1-5/8" 50 state legal headers, Dynomax 3" I pipe (PN 44063 and 43248)
Super GRK_Taz World
F-Body Dual Exaust
EFI & Intake Options


[This message has been edited by Tas (edited November 28, 2001).]

Guest

No, it isnt. As stated above the old HP rating was an engine on a stand with usually absolutely nothing on it, with a specially tuned carb and distributor and headers to tweak the results as much as possible. The new engines are not any sort of rear wheel measurement or estimate, it is a measurement of the power output at the engine's flywheel with all accesories and equipment as it would be if it were installed in a car and sold at a dealer.

Here, dont take my word for it. You can even get the SAE standard for measurement if you'd like.

"Today's horsepower numbers are more accurate, representing what one truly will get in an automobile. Horsepower is measured with accessories, such as the oil and water pump, attached to the engine" http://www.curbsite.com/techforum/horsepower.html

http://www.bonforums.com/mustang/cobra_99dynotest.htm (At bottom, bad example I know but still the number is supposed to meet the 300whatever rated HP. Keep in mind this was a legal matter, so why would it be so far off the advertised?)


"In 1971, a new system of horsepower rating was developed by the Society of Automotive Engineers (SAE), named SAE 342. Engines instead of being tested without accessories and exhaust, are now tested with all accessories attached (things like power steering pumps, generators and fans) and the exhaust system in place" http://www.mtdemocrat.com/archives/a...er100198.shtml (about 2/3 down)

"SAE Net Horsepower: The horsepower of an engine, with engine accessories and exhaust J1349 system operating as measured by Society of Automotive Engineers (SAE) standards. Term often used in predicting and comparing vehicle performance."
http://www.abctruck.com/services/glossary.asp

Internet sources, I know... but it confirms everything I have seen in print for the last 15 or so years. I might advise going to the library and doing a little research, a good library will have the standard used and you can see for yourself exactly what they require.

Tas

ZRATED

Why didn't they ever rate the Ls1 right?
They would have made a bunch of cobra owner's **** in the pants.

Tas

They already do. The f-bodys were underrated and the Corvettes were overrated. Its the same engine, there is only so much you can change. No GM car is ever allowed to be rated more HP than the Corvette. The Grand National was rated under the Vette even though it was faster. The only GM car that got away with having more HP advertised than the vette was the old LS7 454 Chevelle.

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-Tas
'89 Formula WS-6

305, TBI, 700R4, P.A.W. 14x3 open element with K&N, Milodon 160* thermo, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips, Hooker 1-5/8" 50 state legal headers, Dynomax 3" I pipe (PN 44063 and 43248)
Super GRK_Taz World
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75/92 Birdman

iTrader: (4)

The factory HP ratings were at the flywheel. GM's factory ratings at the flywheel are usually within 6hp of the actual HP at the wheels. I don't care what anybody says, it is true. You can dyno a brand new Camaro and it will be that way or you can dyno an old S-10 Blazer with a V6 and it will be the same way. BTW, my old Monte Carlo dynoed 210 at the wheels and it is much slower than my 92 TBI Firebird, which leads me to believe that something is screwey. Just my $.02!

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1975 Firebird - Pontiac 350, TH350, 27k original miles, rustbucket, ongoing resto project

1992 Firebird - 305 TBI, 700R4, sport appearance package, t-tops, flaming red, 89k miles, Weiand 360 air cleaner assembly, CAT Power Engine Parts race underdrive pulleys, more to come....

GKK

I don't know what to believe now. I wish I knew the people that actually dynoed these vehicles from the factory. It seems the best way to tell if the HP is measured from the Rear wheels is to have your car dynoed on the rollers and see if the number is close to 170. If the car dynos at 170 or so at the rear wheels, then that means the engine at the flywheel is making a lot more HP...Right?

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"91" RS, 305 tbi, 5spd, Slp Y-pipe, Random tech Cat, Flowmaster crossflow, Ultimate tbi mods, Edelbrock open element with 3" K&N, Taylor Spiro Pro wires, Redline water wetter, 180* thermostat, Jet-fan switch.

Tas

When I finish this semester I'll try to find my GMHTP that dynoed 10 GM cars. most were well below advertised HP except the camaro. The 300HP cadillac was down around 240 RWHP.

------------------
-Tas
'89 Formula WS-6

305, TBI, 700R4, P.A.W. 14x3 open element with K&N, Milodon 160* thermo, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips, Hooker 1-5/8" 50 state legal headers, Dynomax 3" I pipe (PN 44063 and 43248)
Super GRK_Taz World
F-Body Dual Exaust
EFI & Intake Options

Ride4ME

Is it the heavy stock flywheel that reduces power?

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91 RS
LO3 TBI
"my first car"...
and it's what I always wanted!!!

kd4pbs

Did you guys ever think that maybe some of you went to a dyno tester that puts in a compensation factor for drivetrain loss? THere's already a comp factor for gear ratios thrown in there, maybe they set the dyno up for drivetrain losses as well? It can be done, y'know.

JPrevost

I don't give a **** about hp numbers. Give me best 1/4 mile timeS and mph. Then I'll make my own judgement.

75/92 Birdman

iTrader: (4)

I haven't dynoed my 92 Firebird, but since it has 91k miles it might be off. I know a friend that dynoed his 87 S-10 Blazer when it was new and it was within 6 hp on the factory flywheel rating at the wheels. They also dynoed a new SS Camaro in Muscle Mustangs and Fast Fords(hey, I gotta keep tabs on the competition!) and they got the same results.


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1975 Firebird - Pontiac 350, TH350, 27k original miles, rustbucket, ongoing resto project

1992 Firebird - 305 TBI, 700R4, sport appearance package, t-tops, flaming red, 89k miles, Weiand 360 air cleaner assembly, CAT Power Engine Parts race underdrive pulleys, more to come....