Horse power rating
10-28-2013, 03:35 PM
#1
4th Gear
Thread Starter
Member Since: Oct 2013
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
Horse power rating
Im a member on the Thirdgen.org site (for third generation trans am's and Camaros) and im just trying to get a different view from some corvette experts.
I have a 1983 Trans AM with 1969 corvette double hump heads and cam, and I was just curious what my HP rating might be.
350 junkyard bored 40 over
Cam:
cam lift: int: .298 exh: .298
valve lift: int: .447 exh: .447
lobe ctr: int: hyd exh: hyd
sae duration: int: 291 exh:291
.050 duration: int: 223 exh:223
sae timing: btc:30 abc:81 bbc:78 atc:33
.050 timing: btc:1 abc:42 bbc:49 atc:-6
Heads:
202 int.
160 exh.
Edelbrock RPM Air Gap intake manifold
Edelbrock 750 cfm carb
700R4
1987 TA manifolds, otherwise stock all the way back
3.23 gears posi rear
Ws6 suspension 4 wheel disk.
Street tires
AC delete
Around stock 3,200 Lbs
They tell me the carb is way to much for the engine, which may be trued but its what I have.
I know the rated HP from the factory was 350 and TQ was 380, but I also read on this forum that todays Horsepower is rated differently, but that they also under-rated the HP on rare occations. ( http://forums.corvetteforum.com/c6-c...orsepower.html )
Just kinda curious on HP, TQ, and possible Quarter mile times I might get with these corvette modifications.
-Thanks!
I have a 1983 Trans AM with 1969 corvette double hump heads and cam, and I was just curious what my HP rating might be.
350 junkyard bored 40 over
Cam:
cam lift: int: .298 exh: .298
valve lift: int: .447 exh: .447
lobe ctr: int: hyd exh: hyd
sae duration: int: 291 exh:291
.050 duration: int: 223 exh:223
sae timing: btc:30 abc:81 bbc:78 atc:33
.050 timing: btc:1 abc:42 bbc:49 atc:-6
Heads:
202 int.
160 exh.
Edelbrock RPM Air Gap intake manifold
Edelbrock 750 cfm carb
700R4
1987 TA manifolds, otherwise stock all the way back
3.23 gears posi rear
Ws6 suspension 4 wheel disk.
Street tires
AC delete
Around stock 3,200 Lbs
They tell me the carb is way to much for the engine, which may be trued but its what I have.
I know the rated HP from the factory was 350 and TQ was 380, but I also read on this forum that todays Horsepower is rated differently, but that they also under-rated the HP on rare occations. ( http://forums.corvetteforum.com/c6-c...orsepower.html )
Just kinda curious on HP, TQ, and possible Quarter mile times I might get with these corvette modifications.
-Thanks!
10-28-2013, 03:43 PM
#2
Race Director
That is probaly an L79 or L82 cam.
With headers, 11;1 CR, ported heads and manual trans, I got 300 ft- Tq and 300 HP, both rear wheel numbers on 327 CI.
My '61 Corvette did about 13.8, best time with a DNE 5 speed trans, 3.08 gears. An auto trans should be about 1/2 sec quicker, on a 3000 pound car, heaver car will be slower. Times are for the ~1000 ft MSL altitude.
a 650 would be a better carb choice
YMMV.
Doug
With headers, 11;1 CR, ported heads and manual trans, I got 300 ft- Tq and 300 HP, both rear wheel numbers on 327 CI.
My '61 Corvette did about 13.8, best time with a DNE 5 speed trans, 3.08 gears. An auto trans should be about 1/2 sec quicker, on a 3000 pound car, heaver car will be slower. Times are for the ~1000 ft MSL altitude.
a 650 would be a better carb choice
YMMV.
Doug
10-28-2013, 03:43 PM
#3
Race Director
to me that looks almost stock... small cam, heads are not comparable to todays heads, a bigger carb, and an intake manifold...
so if stock is 350-hp, ///....... i would say 360hp....
so if stock is 350-hp, ///....... i would say 360hp....
10-28-2013, 04:40 PM
#6
Race Director
OK, an L82 cam is 222/222 dur at .050,a nd .450"/.460" lift, I wouldn't say it is no where close to an L46/L82 cam. It not like it a 210 dur, .382" lift, or something
The .447 is L79, but those are 221/221 dur at .050".
I didn't check LSA on an L79 vs what the OP posted.
Doug
The .447 is L79, but those are 221/221 dur at .050".
I didn't check LSA on an L79 vs what the OP posted.
Doug
10-29-2013, 04:49 PM
#7
4th Gear
Thread Starter
Member Since: Oct 2013
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
That is probaly an L79 or L82 cam.
With headers, 11;1 CR, ported heads and manual trans, I got 300 ft- Tq and 300 HP, both rear wheel numbers on 327 CI.
My '61 Corvette did about 13.8, best time with a DNE 5 speed trans, 3.08 gears. An auto trans should be about 1/2 sec quicker, on a 3000 pound car, heaver car will be slower. Times are for the ~1000 ft MSL altitude.
a 650 would be a better carb choice
YMMV.
Doug
With headers, 11;1 CR, ported heads and manual trans, I got 300 ft- Tq and 300 HP, both rear wheel numbers on 327 CI.
My '61 Corvette did about 13.8, best time with a DNE 5 speed trans, 3.08 gears. An auto trans should be about 1/2 sec quicker, on a 3000 pound car, heaver car will be slower. Times are for the ~1000 ft MSL altitude.
a 650 would be a better carb choice
YMMV.
Doug
10:1
10-29-2013, 05:00 PM
#8
Race Director
no... 360 by todays standards with 10:1 compression....
Remember, HP=(tq X rpm)/5252.... and thoes heads/cam stop flowing well before 5krpm
tq is what gets you going, hp is what keeps you going. tq you feel at the stop light, hp is what you use to pass someone with on the freeway...
btw,,, that cam is small...
Remember, HP=(tq X rpm)/5252.... and thoes heads/cam stop flowing well before 5krpm
tq is what gets you going, hp is what keeps you going. tq you feel at the stop light, hp is what you use to pass someone with on the freeway...
btw,,, that cam is small...
10-30-2013, 12:31 PM
#9
4th Gear
Thread Starter
Member Since: Oct 2013
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
no... 360 by todays standards with 10:1 compression....
Remember, HP=(tq X rpm)/5252.... and thoes heads/cam stop flowing well before 5krpm
tq is what gets you going, hp is what keeps you going. tq you feel at the stop light, hp is what you use to pass someone with on the freeway...
btw,,, that cam is small...
Remember, HP=(tq X rpm)/5252.... and thoes heads/cam stop flowing well before 5krpm
tq is what gets you going, hp is what keeps you going. tq you feel at the stop light, hp is what you use to pass someone with on the freeway...
btw,,, that cam is small...
10-30-2013, 12:45 PM
#11
10-30-2013, 12:52 PM
#12
Le Mans Master
Member Since: Mar 2008
Location: Oxford MA-----You just lost the game!!!!
Posts: 5,948
Likes: 0
Received 62 Likes
on
52 Posts
There is no "today's standard". Horsepower is commonly measured in one of three ways: gross, net, and rear-wheel horsepower.
Gross horsepower: measured at the crankshaft, with no engine accessories attached (water pump, alternator, AC, PS, etc.) and open headers.
Net horsepower: measured at the crank (possibly at the tailshaft of the transmission) using attached engine accessories, and full exhaust.
Rear-wheel horsepower: measured at the rear wheels, using a chassis dyno. Drivetrain losses contribute to this method providing the lowest horsepower number.
So, the same engine may make 300 gross horsepower, or 250 net horsepower, or 200 rear-wheel horsepower, as an example. These numbers are probably not completely accurate, I just made them up, but you get the idea.
People in our situation usually talk about gross horsepower, using several expressions, such as "at the crank", to do so, because it is really the best way of eliminating any variables, and comparing one engine to another engine.
Scott
Gross horsepower: measured at the crankshaft, with no engine accessories attached (water pump, alternator, AC, PS, etc.) and open headers.
Net horsepower: measured at the crank (possibly at the tailshaft of the transmission) using attached engine accessories, and full exhaust.
Rear-wheel horsepower: measured at the rear wheels, using a chassis dyno. Drivetrain losses contribute to this method providing the lowest horsepower number.
So, the same engine may make 300 gross horsepower, or 250 net horsepower, or 200 rear-wheel horsepower, as an example. These numbers are probably not completely accurate, I just made them up, but you get the idea.
People in our situation usually talk about gross horsepower, using several expressions, such as "at the crank", to do so, because it is really the best way of eliminating any variables, and comparing one engine to another engine.
Scott
10-30-2013, 03:59 PM
#13
4th Gear
Thread Starter
Member Since: Oct 2013
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
There is no "today's standard". Horsepower is commonly measured in one of three ways: gross, net, and rear-wheel horsepower.
Gross horsepower: measured at the crankshaft, with no engine accessories attached (water pump, alternator, AC, PS, etc.) and open headers.
Net horsepower: measured at the crank (possibly at the tailshaft of the transmission) using attached engine accessories, and full exhaust.
Rear-wheel horsepower: measured at the rear wheels, using a chassis dyno. Drivetrain losses contribute to this method providing the lowest horsepower number.
So, the same engine may make 300 gross horsepower, or 250 net horsepower, or 200 rear-wheel horsepower, as an example. These numbers are probably not completely accurate, I just made them up, but you get the idea.
People in our situation usually talk about gross horsepower, using several expressions, such as "at the crank", to do so, because it is really the best way of eliminating any variables, and comparing one engine to another engine.
Scott
Gross horsepower: measured at the crankshaft, with no engine accessories attached (water pump, alternator, AC, PS, etc.) and open headers.
Net horsepower: measured at the crank (possibly at the tailshaft of the transmission) using attached engine accessories, and full exhaust.
Rear-wheel horsepower: measured at the rear wheels, using a chassis dyno. Drivetrain losses contribute to this method providing the lowest horsepower number.
So, the same engine may make 300 gross horsepower, or 250 net horsepower, or 200 rear-wheel horsepower, as an example. These numbers are probably not completely accurate, I just made them up, but you get the idea.
People in our situation usually talk about gross horsepower, using several expressions, such as "at the crank", to do so, because it is really the best way of eliminating any variables, and comparing one engine to another engine.
Scott
10-30-2013, 05:28 PM
#14
All OEMs have used net HP and only net HP since the early '70s.
Gross and rear wheel HP are kept alive by the aftermarket. Don't know how many times I've heard guys buying a '300HP' crate motor not understand it's gross HP and they'll probably be no better of than their stock L82 producing 210-220 net.
Gross and rear wheel HP are kept alive by the aftermarket. Don't know how many times I've heard guys buying a '300HP' crate motor not understand it's gross HP and they'll probably be no better of than their stock L82 producing 210-220 net.
10-30-2013, 08:06 PM
#15
Race Director
Now I honest to gosh don't know.... So, Don't beat me up over this Mike... So I'm asking if you know, what parasitic if any do the put on crate engines when dyno'ed? Water pump? No yes?
10-30-2013, 08:49 PM
#16
Le Mans Master
GM Parts engine HP ratings are given "as installed" with the full accessory load and stock-type exhaust.
GM Performance Parts engines are given with no accessories, electric water pump and dyno headers with open exhaust.
99.999% of the aftermarket does it the same way the GMPP engines to get big numbers for marketing purposes.
I doubt the OP's engine is making much over 300-325 HP at the crank as installed.
GM Performance Parts engines are given with no accessories, electric water pump and dyno headers with open exhaust.
99.999% of the aftermarket does it the same way the GMPP engines to get big numbers for marketing purposes.
I doubt the OP's engine is making much over 300-325 HP at the crank as installed.
Last edited by billla; 10-30-2013 at 08:52 PM.