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1974 Stingray Dyno Results

Tepot

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Joined
Sep 13, 2005
Messages
307
Location
Moncton, NB, Canada
Corvette
1974 Metalic Blue L-48 Coupe 4 speed
At last guy's, I've finally got the car tuned up on the Chassis Dyno.

Since I've bought the car I've added a few things to my Engine.

1. Changed Points system to electronic ignition system
2. Changed Timing Gears and Timing chain
3. Changed original Cam with Comp Cam XE-268
4. Changed lifters, pushrods, valve springs and seals.
5. Changed Intake for an Edelbrock performer EPS Endurashine
6. Changed Carburetor for an Edelbrock Performer 600 CFM
7. Changed jets and metering rods in Carb for performance and gas economy
8. Changed ignition coil for a Accel performance coil + Summit performance wires
9. Changed 2 Bolt main Block with 4 bolt main and was bored .30 over.
10. K&N Xtreme top and side filters
11. Changed clutch fan for a flex fan with spacer.
12. Headers on true dual 2.5 chambered Exhaust system.

All that brought me to 225 HP @ 4600RPM and 291 ft-lbs Torque @ 3200 RPM at Rear Wheels.

Now I want to know something. My Car came with 195 HP and 175 ft-lbs Torque stock at Flywheel.

How much did I gain? My car as a 4 speed manual transmission. How many % did I lost at the rear wheels? Can someone tell me the percentage lost between flywheel and rear wheels? I'd like to know How I'm making out at the Flywheel to see how much I gain from stock.

here's a picture of the engine bay Before and After all the work.

Before.jpg


After.jpg
 
Joined
Jan 1, 2002
Messages
7,246
Location
Washington, Michigan
Corvette
'67 Marina Blue Convertible
My Car came with 195 HP and 175 ft-lbs Torque stock at Flywheel.

How much did I gain? My car as a 4 speed manual transmission. How many % did I lost at the rear wheels? Can someone tell me the percentage lost between flywheel and rear wheels? I'd like to know How I'm making out at the Flywheel to see how much I gain from stock.

It came with 195hp and 275 ft-lbs. of torque at the flywheel. As a rule of thumb, driveline losses are about 15% with a manual transmission.

:beer
 

KANE

Moderator
Joined
Mar 2, 2002
Messages
3,244
Location
KY
Corvette
Dark Blue 1982 Trans Am(s): Polo Green 1995 MN6
It came with 195hp and 275 ft-lbs. of torque at the flywheel. As a rule of thumb, driveline losses are about 15% with a manual transmission.

:beer

So, according to JohnZ's figures.... you have about 265hp at the flywheel. Not too shabby.

If you crave more power- then look at set of Vortec heads. They are the cheapest in the bang-for-your-buck department. I wouldn't change a thing though. Your current mods have a lot of potential (maybe you need some tuning) and your car looks great!
 

Tepot

Well-known member
Joined
Sep 13, 2005
Messages
307
Location
Moncton, NB, Canada
Corvette
1974 Metalic Blue L-48 Coupe 4 speed
So, according to JohnZ's figures.... you have about 265hp at the flywheel. Not too shabby.

If you crave more power- then look at set of Vortec heads. They are the cheapest in the bang-for-your-buck department. I wouldn't change a thing though. Your current mods have a lot of potential (maybe you need some tuning) and your car looks great!

I've spoke to the Dyno guy, he told me that 15 % lost is for newer vettes C5 and C6. he told me that C3's would loose 25% to 30 %. That's alot of loss.

I was looking for Vortec heads but I've just bought my Endurashine performer EPS intake and it won't fit with vortec heads. So I guess I will have to buy Edelbrock performer RPM Heads. That will be a sure fit. What do you think?
 

KANE

Moderator
Joined
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Messages
3,244
Location
KY
Corvette
Dark Blue 1982 Trans Am(s): Polo Green 1995 MN6
I've spoke to the Dyno guy, he told me that 15 % lost is for newer vettes C5 and C6. he told me that C3's would loose 25% to 30 %. That's alot of loss.

Yikes! That is a significant loss!!

I was looking for Vortec heads but I've just bought my Endurashine performer EPS intake and it won't fit with vortec heads. So I guess I will have to buy Edelbrock performer RPM Heads. That will be a sure fit. What do you think?

Hmmm. Good point- you'd need a new intake to use Vortec heads. I've heard good things about the performer heads when they are matched to Edelbrock intakes.

On the other hand... you could get a hold of GMPP FastBurn heads. They have similar flow patterns to the Vortec heads. They also fit Vortec and standard bolt patterns- which would allow you to retain that great intake.
 

Crimson Thunder

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Joined
Dec 16, 2001
Messages
814
Location
Orange Park FL USA
Corvette
1970 Marboro Maroon Convertible
You probably lost 10 horsepower when you switched from the clutch fan to the flex fan.The Performer heads will be perfect for your combo.(268cam600cfm carb)The Fastburns with their 210 intake ports will make your car lazy on the bottom end.You've done a great job on your car so far.
 

Tepot

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Joined
Sep 13, 2005
Messages
307
Location
Moncton, NB, Canada
Corvette
1974 Metalic Blue L-48 Coupe 4 speed
On the other hand... you could get a hold of GMPP FastBurn heads. They have similar flow patterns to the Vortec heads. They also fit Vortec and standard bolt patterns- which would allow you to retain that great intake.

where would I get those heads? How much HP can I get with those? Are they gonna give me more HP than the Edelbrock performer heads?
 

Tepot

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Joined
Sep 13, 2005
Messages
307
Location
Moncton, NB, Canada
Corvette
1974 Metalic Blue L-48 Coupe 4 speed
You probably lost 10 horsepower when you switched from the clutch fan to the flex fan.The Performer heads will be perfect for your combo.(268cam600cfm carb)The Fastburns with their 210 intake ports will make your car lazy on the bottom end.You've done a great job on your car so far.

Ok. well if you say so, I'll go with the Edelbrock performer RPM heads. I like the name Edelbrock and I think it will work good with my intake and carb.

will they give me an extra 50 HP at the engine you think?
 

Crimson Thunder

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Joined
Dec 16, 2001
Messages
814
Location
Orange Park FL USA
Corvette
1970 Marboro Maroon Convertible
Depends on what heads you have on your motor now.If you have set of small valve/76cc chamber heads(giving you low compression)on your motor now,then you will see a nice HP increase with the Performer RPM's.
 

Tepot

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Joined
Sep 13, 2005
Messages
307
Location
Moncton, NB, Canada
Corvette
1974 Metalic Blue L-48 Coupe 4 speed
Depends on what heads you have on your motor now.If you have set of small valve/76cc chamber heads(giving you low compression)on your motor now,then you will see a nice HP increase with the Performer RPM's.

I have the original L-48 heads. don't know what they are but if the car came with only 195 HP stock. I don't expect them to be too performant. the guy at the performance shop told me that I would gain 55 HP but didn't mentioned if it was at the flywheel or at the wheels. I suspect probably at the flywheel.
 

Wayne robson

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Feb 24, 2007
Messages
169
Location
australia
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sold my last corvette.
flex fan warning

Hello Tepot, i dont want to think im am being smart, but i want to give you a bit of ad vise, i lived in sacramento for aprox 10 years its very hot there approx 3 months of the year 100 to 110 degress anyway i own a 65 buick riviera, and a friend of mine there fitted a flex fan just like yours to his 65 riv gs, it was,allways overheatting ,his fan actually came off went through his radiator made a hell of a mess, what can happen is because of the long spacer,the bolts have to have a quility spring washer, and be torqued to 30pound, very even , if not done even the alloy spacer can riggle loose and flex fans can be a little noisy most times anyway but if bolts losen look out,and in the end the cooling problem was a after market cheap rebuilt water pump with only three pump blades that were shorter than was normal. regards wayne.
 

Tepot

Well-known member
Joined
Sep 13, 2005
Messages
307
Location
Moncton, NB, Canada
Corvette
1974 Metalic Blue L-48 Coupe 4 speed
Hello Tepot, i dont want to think im am being smart, but i want to give you a bit of ad vise, i lived in sacramento for aprox 10 years its very hot there approx 3 months of the year 100 to 110 degress anyway i own a 65 buick riviera, and a friend of mine there fitted a flex fan just like yours to his 65 riv gs, it was,allways overheatting ,his fan actually came off went through his radiator made a hell of a mess, what can happen is because of the long spacer,the bolts have to have a quility spring washer, and be torqued to 30pound, very even , if not done even the alloy spacer can riggle loose and flex fans can be a little noisy most times anyway but if bolts losen look out,and in the end the cooling problem was a after market cheap rebuilt water pump with only three pump blades that were shorter than was normal. regards wayne.

Thanks for the advise !!! I will make sure to check the fan condition often and use those spring washers and make sure to torque @ 30 Pounds each bolts. I apreciate the advise Wayne.
 
T

TMPJoe

Guest
You probably lost 10 horsepower when you switched from the clutch fan to the flex fan.The Performer heads will be perfect for your combo.(268cam600cfm carb)The Fastburns with their 210 intake ports will make your car lazy on the bottom end.You've done a great job on your car so far.

I agree with that.. given that cam and the intake and carb set up... the edelbrock heads are a good choice

what are you running for pistons? compression still way down?

You mentioned springs.... make sure they are not too heavy for the heads you are using... thats not a wild combo and sometimes people have too much spring pressure.... ask around a bit.. my $.02 tip
 

Tepot

Well-known member
Joined
Sep 13, 2005
Messages
307
Location
Moncton, NB, Canada
Corvette
1974 Metalic Blue L-48 Coupe 4 speed
I agree with that.. given that cam and the intake and carb set up... the edelbrock heads are a good choice

what are you running for pistons? compression still way down?

You mentioned springs.... make sure they are not too heavy for the heads you are using... thats not a wild combo and sometimes people have too much spring pressure.... ask around a bit.. my $.02 tip

Not sure about the pistons. But I think they are not much performant. could be stock. the only thing I know is that it was rebuilded at least once. bored to 30 over. that's it. I don't think they are performance pistons.

I wonder how much new performance pistons + performer heads would give me Horse power wise?
 

Bob Onit

Member
Joined
Jul 15, 2006
Messages
7
Location
Ct
Corvette
Very Clean 73 Coupe,L48 New paint
Now I want to know something. My Car came with 195 HP and 175 ft-lbs Torque stock at Flywheel.
Hi Tepot
One thing you should know is that the '74 stock L-48 was quite a bit more than 195 HP @ the flywheel.
I have also spoke with people that have done flywheel dynos on stock L-48's and they are in the 250+ HP range.
HP ratings were skewed in the early 70's for various reasons.
Hope this helps.
:beer
______________________________
1973 Coupe
32,000 Original miles.
L-48
RHS Pro Torker heads
Crane Z cam.
Crane Magnum roller tip rockers .
Edelbrock 2101/Q-Jet.
Distributor by Lars.
 

80Vette

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Joined
Jul 3, 2006
Messages
63
Location
Portland OR
Corvette
1980 pearl white vette
I have the original L-48 heads. don't know what they are but if the car came with only 195 HP stock.......


Those are actually pretty decent numbers on the factory heads. I too have the performer intake/carb combo. I too ran about the same dyno numbers as you for HP. But, my torque readings were a bit higher. It sounds like your dyno was on a Mustang Dyno? Yes, no? That'll tell you a lot about your HP readings.

The good news: You do have nearly 300ft lbs of torque. That is the real "Whhaaaumph" factor on these SBC. When you read that a new Honda claimes to have 250hp. That is typically factory hogwash at the crank (IMHO). The torque numbers are what you "feel" when you stomp on it.:cool
 
T

TMPJoe

Guest
tepot

At this point you really have a kid of mongrel motor.. no offense..

if it was overbored the usual 30 over, then chances are something is up with the pistons... also doing that and putting the heads back in place with no work to them I would be suspect of why anyone would..

before buying the heads and going deeper into an unknown on top of the motor....

I would go ahead and plan the time to pull the motor and see whats on the inside.... think about some new rods pistons and bearings if necessary....

that way when you order the heads you can be sure what you are actually putting them on....

thats what I would recommend... either way its a lot easier to put the new parts on with the motor out of the car...


you can check timing chaing, oil pump, water pump while you are at it...
 

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