C3...anemic HP...Help
Thread Starter
Burning Brakes
Joined: Jul 2006
Posts: 830
Likes: 1
C3. Dyno confusion
Hey all, our corvette group had a Dyno-Day and I was the only C3 representing.
I have a 350, brand spankin new Edelbrock Performer intake & carb, an aftermarket slightly beefier cam & shorty headers to a 3" Y pipe which is married to a free flow 3" cat, from the cat back it's true 3" exhaust to the magnaflow 40's.
I was thinking that the car would at LEAST get 330HP.
But, on the MustangDyno I only pulled a 281. Three times in a row.
.
Andy
I have a 350, brand spankin new Edelbrock Performer intake & carb, an aftermarket slightly beefier cam & shorty headers to a 3" Y pipe which is married to a free flow 3" cat, from the cat back it's true 3" exhaust to the magnaflow 40's.
I was thinking that the car would at LEAST get 330HP.
But, on the MustangDyno I only pulled a 281. Three times in a row.
.Andy
Last edited by OregonVette80; Dec 19, 2015 at 12:46 PM.
Safety Car
Joined: Aug 2000
Posts: 3,909
Likes: 26
From: Clymer PA
I'm not sure what your rear end/transmission combination is but some decent flowing heads with a matching camshaft and a nice header exhaust will put you over the 250 horsepower mark. It's really not very difficult to get some good horsepower and torque out of a sbc.
Last edited by bence13_33; Oct 30, 2006 at 03:26 PM.
Pro
Joined: Nov 2004
Posts: 677
Likes: 0
From: Frisco TX
What year is your Vette? Becuase that sounds about right if not a bit high. I have an 89 and a 76 Vette and my 89 with FI and better gearing\transmission only put 232HP at the rear wheels.
My 89 can run circles around my 76. If you have a Mid-70s C3 then you are right in the middle of the Smog era. I think some of the motors in this time frame only had around 220HP at the crank. With a 20% due to drive train you are right about where you should be.
With the changes you made it should have been a bit higher but it depends on what else you have going on. The shorty headers, depending on the maker, are at times no better than the stock iron headers. Switching from single exhaust to dual exhaust might help. Since you have allready went down the path of getting the air out of the car you need to look at how you are getting in into your motor.
Higher flowing carb and higher flowing heads will help a TON. The heads are probably what is really killing you right now. If you are running the stock heads then that is what I would change next. Adding the intake and exhaust that you have will not help at all if the heads can't get the gas into the cyl.
Tim
My 89 can run circles around my 76. If you have a Mid-70s C3 then you are right in the middle of the Smog era. I think some of the motors in this time frame only had around 220HP at the crank. With a 20% due to drive train you are right about where you should be.
With the changes you made it should have been a bit higher but it depends on what else you have going on. The shorty headers, depending on the maker, are at times no better than the stock iron headers. Switching from single exhaust to dual exhaust might help. Since you have allready went down the path of getting the air out of the car you need to look at how you are getting in into your motor.
Higher flowing carb and higher flowing heads will help a TON. The heads are probably what is really killing you right now. If you are running the stock heads then that is what I would change next. Adding the intake and exhaust that you have will not help at all if the heads can't get the gas into the cyl.
Tim
Drifting
Joined: Nov 2004
Posts: 1,971
Likes: 7
From: Longwood Florida
Originally Posted by OregonVette80
Hey all, our corvette group had a Dyno-Day and I was the only C3 representing.
I have a 350, brand spankin new Edelbrock Performer intake & carb, an aftermarket slightly beefier cam & shorty headers to a 3" Y pipe which is married to a free flow 3" cat, from the cat back it's true 3" exhaust to the magnaflow 40's.
I was thinking that the car would at LEAST get 230HP.
But, on the MustangDyno I only pulled a 181. Three times in a row.
I mean, my wifes saturn has a Yamaha DOCH V6 which will pull a 210hp on the dyno.
What I want to know is, how can I get my 350 to perform better?
It shouldn't be THAT hard to get 250hp out of a SB chevy, right?
Andy
I have a 350, brand spankin new Edelbrock Performer intake & carb, an aftermarket slightly beefier cam & shorty headers to a 3" Y pipe which is married to a free flow 3" cat, from the cat back it's true 3" exhaust to the magnaflow 40's.
I was thinking that the car would at LEAST get 230HP.
But, on the MustangDyno I only pulled a 181. Three times in a row.
I mean, my wifes saturn has a Yamaha DOCH V6 which will pull a 210hp on the dyno.
What I want to know is, how can I get my 350 to perform better?
It shouldn't be THAT hard to get 250hp out of a SB chevy, right?
Andy
Your car should make more power than that ??
How does it run ??
WHat kind of torque did it make?
What stall converter are you running?
DO you have REALLY tall tires in the back??
What is your timing set at ??
And we all assume you are running factory heads...but you should make more power than 181 ?? guessing about 8.5 to 1 compression. That 3in exhaust doesn't help you...with a mild motor
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Burning Brakes
Joined: Jul 2005
Posts: 787
Likes: 0
Originally Posted by OregonVette80
Hey all, our corvette group had a Dyno-Day and I was the only C3 representing.
I have a 350, brand spankin new Edelbrock Performer intake & carb, an aftermarket slightly beefier cam & shorty headers to a 3" Y pipe which is married to a free flow 3" cat, from the cat back it's true 3" exhaust to the magnaflow 40's.
I was thinking that the car would at LEAST get 230HP.
But, on the MustangDyno I only pulled a 181. Three times in a row.
I mean, my wifes saturn has a Yamaha DOCH V6 which will pull a 210hp on the dyno.
What I want to know is, how can I get my 350 to perform better?
It shouldn't be THAT hard to get 250hp out of a SB chevy, right?
Andy
I have a 350, brand spankin new Edelbrock Performer intake & carb, an aftermarket slightly beefier cam & shorty headers to a 3" Y pipe which is married to a free flow 3" cat, from the cat back it's true 3" exhaust to the magnaflow 40's.
I was thinking that the car would at LEAST get 230HP.
But, on the MustangDyno I only pulled a 181. Three times in a row.
I mean, my wifes saturn has a Yamaha DOCH V6 which will pull a 210hp on the dyno.
What I want to know is, how can I get my 350 to perform better?
It shouldn't be THAT hard to get 250hp out of a SB chevy, right?
Andy
Theres no way a mid 70's stock is going to push 275 plus HP at the crank.....and I suspect those who dropped in a 330HP GM crate would be unpleasantly surprised at the HP reading on a CHASSIS dyno, at least with a slushbox
Thread Starter
Burning Brakes
Joined: Jul 2006
Posts: 830
Likes: 1
Here's what it looks like.
It's a 1980 with a 350cu in. It is a new (completely remanufactured) engine with 6,000 miles on it.
I'm not sure what the cam size is but the mechanic who did the work did have to advance the timing to cooperate with the cam. I wish I knew.
But, yes...It does have the original heads. Also, on the dyno it was pretty clear that the primaries are running too lean and the secondaries were very late in opening (bad or weak counterbalance spring?). But, when the secondaries did open, they were too rich.
Oh...the sticker came with the air-cleaner
it was the only model we could fit in their without cutting.Since I never use the A/C could I just simply remove the pump & cap the hoses?
Cruising
Joined: Sep 2006
Posts: 13
Likes: 0
From: North Babylon New York
I agree a new set of heads would help a ton. I have an 81. Went down the same road as you with edlebrock carb/intake. Haven't dyno'd yet but am curious. I saw in your pic. on the exhause manifold there is an open inlet. I capped mine with a piece of hose and a clamp until I go with headers someday. Yes, I took all the a/c components out (kept them for future) and it opens up alot of room, no problems. My wife also has the Saturn w/ the L66 motor. It's manuf. by Honda. YOu can find it in the Pilot. It says it gets 250hp. It really goes for a Vue!
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
Originally Posted by OregonVette80
Hey all, our corvette group had a Dyno-Day and I was the only C3 representing.
I have a 350, brand spankin new Edelbrock Performer intake & carb, an aftermarket slightly beefier cam & shorty headers to a 3" Y pipe which is married to a free flow 3" cat, from the cat back it's true 3" exhaust to the magnaflow 40's.
I was thinking that the car would at LEAST get 230HP.
But, on the MustangDyno I only pulled a 181. Three times in a row.
I mean, my wifes saturn has a Yamaha DOCH V6 which will pull a 210hp on the dyno.
What I want to know is, how can I get my 350 to perform better?
It shouldn't be THAT hard to get 250hp out of a SB chevy, right?
Andy
I have a 350, brand spankin new Edelbrock Performer intake & carb, an aftermarket slightly beefier cam & shorty headers to a 3" Y pipe which is married to a free flow 3" cat, from the cat back it's true 3" exhaust to the magnaflow 40's.
I was thinking that the car would at LEAST get 230HP.
But, on the MustangDyno I only pulled a 181. Three times in a row.
I mean, my wifes saturn has a Yamaha DOCH V6 which will pull a 210hp on the dyno.
What I want to know is, how can I get my 350 to perform better?
It shouldn't be THAT hard to get 250hp out of a SB chevy, right?
Andy
I see you are running an 80 shark. Be sure you have the right advance curve; you can pick up alot of power with the right advance curve. And the car will seem underpowered if you are running the stock timing/advance. I paid $250 to a tuner that had a dyno to lay a nice new advance curve down on my Accel Performance Replacement distributor; made a big difference.
what air/fuel ratio numbers was your car producing? That will tell you if you need to lean/richen which can also free up some power.
Last edited by TedH; Oct 30, 2006 at 06:05 PM.
Drifting
Joined: Nov 2004
Posts: 1,971
Likes: 7
From: Longwood Florida
Running stock L48 manifold and 3 in exhaust 
I would pay somebody to adjust your carb and timing...
that alone should give you about 15-20 rwhp... sounds like your car does not perform well.
bone stock smog L48 should make about 140-150 rwhp with 20 drive train loss.
a new cam, intake, carb , true duals should bring you to about 200rwhp...get some long tube headers about 10-15rwhp and decent set of heads with a small chamber 58-64 cc and you should be over 250-260 rwhp.
I would pay somebody to adjust your carb and timing...
that alone should give you about 15-20 rwhp... sounds like your car does not perform well.
bone stock smog L48 should make about 140-150 rwhp with 20 drive train loss.
a new cam, intake, carb , true duals should bring you to about 200rwhp...get some long tube headers about 10-15rwhp and decent set of heads with a small chamber 58-64 cc and you should be over 250-260 rwhp.
Thread Starter
Burning Brakes
Joined: Jul 2006
Posts: 830
Likes: 1
Originally Posted by holley505
I would pay somebody to adjust your carb and timing...
that alone should give you about 15-20 rwhp... sounds like your car does not perform well.
...get some long tube headers about 10-15rwhp and decent set of heads with a small chamber 58-64 cc and you should be over 250-260 rwhp.
that alone should give you about 15-20 rwhp... sounds like your car does not perform well.
...get some long tube headers about 10-15rwhp and decent set of heads with a small chamber 58-64 cc and you should be over 250-260 rwhp.
I really appreciate this thread guys.
Andy
Melting Slicks
Joined: Sep 2002
Posts: 2,783
Likes: 2
From: Engineers do it better.
Originally Posted by holley505
Running stock L48 manifold and 3 in exhaust
I would pay somebody to adjust your carb and timing...
that alone should give you about 15-20 rwhp... sounds like your car does not perform well.
bone stock smog L48 should make about 140-150 rwhp with 20 drive train loss.
a new cam, intake, carb , true duals should bring you to about 200rwhp...get some long tube headers about 10-15rwhp and decent set of heads with a small chamber 58-64 cc and you should be over 250-260 rwhp.
I would pay somebody to adjust your carb and timing...
that alone should give you about 15-20 rwhp... sounds like your car does not perform well.
bone stock smog L48 should make about 140-150 rwhp with 20 drive train loss.
a new cam, intake, carb , true duals should bring you to about 200rwhp...get some long tube headers about 10-15rwhp and decent set of heads with a small chamber 58-64 cc and you should be over 250-260 rwhp.
In summary,
L-48: under 170 rwhp
cam/intake/exhaust: around 200 rwhp
heads/headers: 250+ rwhp
Assuming the pistons are stock.
Racer
Joined: May 2006
Posts: 379
Likes: 0
From: greenville al
I have an 80 that had an L48. Pitiful power! Over the summer I have installed a 383 GM crate motor which was tweaked by Sallee Chevrolet. 450 hp at the crank, and I installed a level 3 700R4 from bowtie overdrives. It is fabulous. The only thing left to do now is the rearend. I also have an 01 Z06, and it is very close to running with it off the line. Hopefully, the lower gears in a few weeks will help. Check out Sallee Chevrolet performance which I think is now ?Gilbert Chevrolet.
