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Discussion Starter #1
Just thought I see if anyone else felt this way when they threw in a new engine....or just your thoughts.

I've put in the GM 350 H.O. / 330 hp Crate in my 1979 Vette with a new 700r4
It just is not enough Power for Denver Metro Area (appx 5500' altitude). If anyone else going to buy this motor I'd reccommend something with higher revs and more power.


1979 Corvette (Specs)

Dyno Results....
Max Rear wheel HP 237 @ 4900
Max Rear wheel Torque 278 @ 3700

350 H.O. GM Crate Engine
330hp @ 5000 rpm
380ft.lbs @ 3800 rpm
Compression 9.1:1
Max RPM 5500
64cc Vortec Heads
Camshaft:
Lift: .435” Intake, .460 Exhaust
Duration @ .050: 212 Degrees Intake, 222 Deg Exhaust.
HEI Distributor: -50,000 volt spark (Re-curved)
Fluidampr Harmonic Balancer
Carburetor:
Edelbrock Performer Quadrajet
795 CFM...........(Dyno Tuned)

Transmission:
TH-700r4
2200 Stall Converter
Rear End Gear: 3.55.
Exhaust:
Dual / with Dual Cats.
2-1/4” Pipe with H-pipe & Turbo Mufflers
 

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What about the GM ZZ4 crate motor

Sorry to hear about your disappointment. My 73 vette used to live in Colo Springs and I agree, the altitude definately reduces performance. Is there any reason you didn't consider GM ZZ4 motor? It's supposed to deliver 355HP and 405ft/lbs torque. I am considering this motor myself. Does anyone have this in there C3???

John
 

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Discussion Starter #3
I basically didn't go with the ZZ4 because of price and I was looking for more of a long block. If I had to do it again I'd go with the GM crate 383 with 425 hp and the 6300 redline, but I would start wondering if the stock rearend would be able to hold that kind of power.
 

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I have to disagree with you. I put the 330 hp vortec in a 79, built to the recommended specifications, using a Holley 750cfm and Bowtie intake with the stock turbo 350 built up. The car was absolutely awesome. It was very fast, and frequently outran cars that it should have lost to. It had great driveability, and was completely worry free.

I can't believe you had a problem with yours. Perhaps you just got a bad engine.

Here's mine:
 

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I have to disagree with you also. i had one in my 69 camaro with a turbo 350 and 3.73 posi. it out ran a lot of cars. i ran a 13.50 with crappy tires at the track. i would say bad motor also or play with the carb more. for the money its a great deal.
 

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I agree. You guys from Az, or Ms don't have that problem with altitude.

...High alt does make a big difference.... it even mentions that in my stock '79 shop manual.
 

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Repo73Vette said:
... Does anyone have this in there C3???

John

I'll let you know this summer. My ZZ4 just arrived today but I need some other parts which will delay the install. Hopefully it will do the job and put down some power.
 

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I have 57 Nomad with a ZZ1 engine and a 57 Bel Air sedan with the ZZ3 engine, now the sedan is a much quicker more responsive car but both I feel are quite the rides and the way to go, I have had engines rebuilt and they turned out to be nothing more than a good boat anchor. I am also am running 650 Holleys on both engine and feel that at Denver high altitude it is a better choice than the larger carbs. Both cars have 3.40 gearing and turbo 400 trans with a BM holeshot converters. Just my 2 cents.
 

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Jet down the carb

Came from sea level and when I got into the mountains the car felt like I was pulling an anchor. Had a holley 600 vacuum secondary on a mildly built 350 and jetted it down 2 sizes on the primary while I was out there working . This didin't give all the power back but did help. I find lots of people go overboard on the carb size on the street only to find out later that a smaller cfm carb performs better and has crisper throttle response.

good luck and if you get a chance try a 600 or 650 cfm vacuum secondary carb and see if it makes better HP in the thinner air.
Dandy Don
 

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Discussion Starter #10
!. The Dyno shop that tuned the car ran different carbs on that engine; a Holley 750 double pumper had 5 hp more (would use loads more gas/ hood clnc issues), edlebrock 650, and another quadrajet produced the same power. Unless I did a different Cam or did some head work their is not much that will make high power gains keeping it normally aspirated. It's a new engine...why bother?

2. The engine is quick, but not fast. It was my hopes that it would beat a new 05/ 06 Mustang GT, but after test driving a new Mustang GT I can honestly say that it will not happen. Someone down below mentioned the value that the 350/ 330hp crate has for the HP ...I agree, but when I was choosing the engine I should have been more critical in my decision...another 2g up front would have added alot more power, which, is what I wanted.

3. Most important.....it's a Corvette and I wouldn't dream of having anything else beside a Corvette, but if I could do it again I'd go for more power.
 

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There's no reasons you're car shouldn't outrun a mustang with 330hp... Both cars weigh nearly identical and you're winning in the power department, so whats the problem :surprised :surprised
 

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you need to be carefull with crate motors. they measure HP at the crank. all the newer cars, since '71 or '72, are measured at the tires. the whole gross vs net HP thing. if you're getting 240HP at the tires and at 5500ft. that's not bad with the 350 HO motor. it's not going to be close against a new Rustang, they run 100 HP more at the tires than what you have. i also think you are running a little rich with the carb. dyno runs tend to be rich to make best power under max load. unfortunately street driving does not reflect maxium load, you get less load due to accelleration. check the color of your spark plug insulators to determine how it's running. or if you have an extra $350 laying around, buy a LM-1 tuner from Innovative Motorsports. i love mine, taught me worlds about tuning for the street.
 

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Discussion Starter #14
Thanks for the reply....not sure I agree with you on how HP is measured; so below I pasted in what I found on http://en.wikipedia.org/wiki/Horsepower. Basically, the new Mustang has got me on one area... higher Red line. My car and the new Mustang are very close in specs. From what I've seen on the dyno measurements around the web; with the new Mustang at various places around 1000' alt, a new stock Mustang runs 260hp to 271hp at the rear. So until the rubber meets the road its all just beauty shop talk. But, I really appreciate the heads up on LM-1 tuner from Innovative Motorsports. Thanks!

Horsepower Defined

SAE gross horsepower
Prior to 1972 most American automakers rated their engines in terms of SAE gross horsepower (defined under SAE standards J245 and J1995). Gross hp was measured using a blueprinted test engine running on a stand without accessories, mufflers, or emissions control devices. It therefore reflected a maximum, theoretical value, not the power of an installed engine in a street car. Gross horsepower figures were also subject to considerable adjustment by carmakers: the power ratings of mass-market engines were often exaggerated, while those for the highest-performance muscle car engines were frequently underrated.

(SAE) Net
In the United States the term "bhp" fell into disuse after the American Society of Automotive Engineers (SAE) recommended manufacturers use hp (SAE) to indicate the net power of the engine, given that particular car's complete engine installation. It measures engine power at the flywheel, not counting drivetrain losses.
Starting in 1971 automakers began to quote power in terms of SAE net horsepower (as defined by standard J1349). This reflected the rated power of the engine in as-installed trim, with all accessories and standard intake and exhaust systems. By 1972 U.S. carmakers quoted power exclusively in SAE net hp. The change was meant to 'deflate' power ratings to assuage the auto insurance industry and environmental and safety lobbies, as well as to obfuscate the power losses caused by emissions-control equipment.
SAE net ratings, while more accurate than gross ratings, still represent the engine's power at the flywheel. Contrary to some reports, it does not measure power at the drive wheels.
Because SAE gross ratings were applied liberally, at best, there is no precise conversion from gross to net. Comparison of gross and net ratings for unchanged engines show a variance of anywhere from 40 to 150 horsepower. The Chrysler 426 Hemi, for example, in 1971 carried a 425 hp gross rating (often considered to be underrated) and a net rating of 375 hp.

SAE-certified horsepower
In 2005, the Society of Automotive Engineers introduced a new test procedure (J2723) for engine horsepower and torque. The procedure eliminates some of the areas of flexibility in power measurement, and requires an independent observer present when engines are measured. The test is voluntary, but engines completing it can be advertised as "SAE-certified".
Many manufacturers began switching to the new rating immediately, often with surprising results. The rated output of Cadillac's supercharger Northstar V8 jumped from 440 hp (328 kW) to 469 hp (350 kW) under the new tests, while the rating for Toyota's Camry 3.0 L 1MZ-FE V6 fell from 210 hp (157 kW) to 190 hp (142 kW). The first engine certified under the new program was the 7.0 L LS7 used in the 2006 Chevrolet Corvette Z06. Certified power rose slightly from 500 hp (373 kW) to 505 hp (377 kW).
 

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when you live at altitude you need higher compression. My house and the majority of my local driving is between 4400 and 8900 feet. So I built motors with high 10:1 or even in the case of my 383 was 11.2

That and blowers is what piston airplanes do.
 

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Discussion Starter #16
That's one aspect I did not think of...but you are right; even a Cessna 172 has pretty high compression. A new Mustang runs 9.8:1.
 

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All the pro catogory NHRA boys run higher compression motors just at the Denver race to make up for the thin air.
 
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