When I bought my 1984 Z28 with the origional 305.H.O. Quadrajet dual snorkel air cleaner I checked all ythe numbers on the VIN, block, and in the glove box, according to the engine code that engine was rated by the factory for 190 h.p., curiously, I was wondering if the factory under or overrated the horse power or is it on the money? Since I did all the number checking I've had it bored out 30 over polished crank, small duration WEdelbrock cam/lifters,Edelbrock performer intake and 600 cfm electric choke with Acell ignition and wires plus shortie headers and 2 1/2 exhaust.

 

They were underrated... or at least that is what everyone will tell you.

Don't try the add 10hp for this, 20hp for that method though, doesnt work that way. Best way to find out is to measure it or run the car and calculate it (which isnt entirely accurate either). That or just be happy with it without knowing what its putting down

 

In stock form, it would not only beat, but really EMBARASS a 205hp Corvette of the same year. Think about that

 

There were no Corvettes the same year as mine to embarass.....think about THAT!!!

 

If you look at the numbers, they were rated about where they should be.

As for beating the 'Vette, some did. Gearing had a lot to do with that as the F-Body had better tranny gearing and rear gears.

Why everybody thinks that GM underrated all these cars is a mystery to me. Just because the LS1 was way underrated doesn't mean that all the other small blocks were.

 

Actually, it had more to do with it than just gearing. The base HP rating and torque of the L69 exceeded that of the 'Vette CFI....that was the best engine for a 'Vette you could get in '82.....regardless - I can beat any stock '83 'Vette out there.

P.S. - overrated?? nope. Underrated? Probably not....

 

Actually IIRC in 1982 the Vette Cross Fire was 200hp and 285tq and in 1984 it was 205hp and 290tq.

 

Have you run one? I know of one that is in the 'Vette Museum. Looks like a '84 but has 15" wheels. I'm sure it was a dog like any other cross fire but they did make one '83

 

OK - Ya got me there!!

Pull it outta the museum.....I'll run it!

 

HA! There were no 83 Vettes!

 

There is one...in Bowling Green KY. The other 14 or so 83 Corvettes were destroyed by GM. Seems they made about 15 before abandoning the 83 model year. No one seems to believe this story, but if you go to the Corvette museam and look at the one and only 83 corvette you too will hear the same thing.

 

They didnt make a 83 Corvette because they couldn't meet EPA regulations in time.

 

All of the 83's made where pre-production test cars and if you will look at the fit and finish on the 83 at the museum you will see that it is not up to standard and borderline on just plain horrid the car waves at you and just in general looks like it was slapped together. I also have noticed it is now sporting 16's for some reason and the stickers are gone from the windows that were there the last time I saw it about a year ago. I think there may be more than one left in GM's pocket.

 

If you guys could get it out of there (Yeah Right) At least the track would be close Beech Bend is only about 15 min from the museum.

 

That much???

That's quite an increase from the 175 HP rating the Firebird/Camaro Crossfires got in '83.....L69 was 190 HP. The 1983 Z28 L69 HO cars were the fastest cars GM produced that year, hands down. Since they didn't start actually making them till mid '83, it is also pretty rare. Not too many sold...like 2900 out of like, 10,000 F-bodys produced that year. Not sure if the L69 engines came in 'birds or not that year...hmmmm

Anyways I was told it was built to try and compete with Mustangs of the year, which it did well. Remember, I said Mustangs of the year!! (83)

But I may be making this up cause I'm biased...

IMO it wasn't a good year for any make of car because the car companies were struggling on how to make stricter emissions standards....by detuning what they had. You should see the miles of hoses under my hood!! EGR, AIR system etc...

 

Remember the Corvette sported 45 more cubic inches and made a lot more torque 240->290. I'm not sure what the 83 hot air GN was running, but it would be right up there with the L69.

 

My whole point in specifying 83, is because the Corvette didn't sport 45 more cubes or ANYTHING in 1983 since Corvettes never hit production that year! If Buick produced GN's in '83, then I may stand corrected on this one, although I don't recall any that early....

 

Oh they were making GN's in 83, but that was the last year of the suck through carb turbo setup; 84 they went to SFI. Not really all that quick, I'm sure the L69 5-speed was faster.

 

There were no GNs in 83. There were turbo regals, I think this was the first year of the T-type (prior years they were called turbo sport coupes). There was an 82 GN (package to celebrate Buick winning Nascar's Grand National manufacturers cup) but the 82 could be ordered seperately of the turbo sport coupe. There are turbo and NON-turbo 82 GNs. The black turbo grand nationals were from 84 - 87.

 

Ok yes thanks for clearing that up. In 83 only T-Types were produced. IIRC they made 190hp and 280tq.

 

Ok, the '84 HO (with T5) was faster, by a staggering amount, than the '84 Corvette.

The '83s were faster than the '84 HOs too. Not by much though, and mostly due to weight. The '83s had some lighter parts than the '84s, like the fibreglass hood, and I think the bellhousing was lighter too, but not sure on that one.

So the '84 HO cars were faster than '84 Corvettes, and the '83s were faster than both

 

You know I gotta say it ...I told you....but I won't.

Not too big of a HP advantage. The '82 CFI Vettes were only rated at 160 HP, and the 84's got bumped to 175.....I'll say THIS again, lousy year for cars so far as HP and torque go.

But the 83 and 84 L69 Z28 cars were pretty much identical. The 84 autos were a smidge slower than the 83 OR 84 T-5's. T-5's are lighter, and less drivetrain loss....

Put a 83 or 84 L69 5 speeds together....I don't think a fiberglass hood makes that big a diff. Just my 2 cents!!

EDIT: Think about it.....only a 15 HP diff between a 84 L69 (at 190HP) and a 84 CFI Vette (at 175HP)!! and Vettes are lighter!!!....

 

Dude you're thinking about the 305 Cross-Fire.

The 1982 Vette was 200hp and 285tq and the 84 was 205hp and 290tq.

 

Man!!! - It's late!!!.....I meant to say the Z28 CFI's in '82 were 160 and bumped to 175......not sure why I said Vette....forget what I said about Vettes....

Your right...:hail: , I'm wrong. Feel free to delete my above post moderator!!

But what I said about 83 and 84 L69 Z28's still stands!!

 

I would have to say they were underrated from my experience.
Bought a bone stock 84 T5 with 52,000 original miles. I gutted the cat, played with the secondaries, replaced the coil with a hotter one. Changed the spark plugs, put Mobil 1 in and took it
to the strip were it went 95 mph in the traps. Calculating using
conservative weight numbers that equals 215 hp at the rear
wheels ! That puts flywheel hp in 240-250 range.

 

Well, the reason the T5 L69 cars are faster than autos is not so much the weight, but the gearing.

The T5 has more aggressive gear ratios than the 700R4 does, and the T5 cars got the 3.73 gears too.

 

Oh - And all this time I thought the slippage and drivetrain loss was higher on an auto as compared to a manual.

Learn something new everyday.....

 

It is higher and does play a huge factor in getting power to the rear wheels.

 

Thx.. I know. I was just answering Air_Adam's post.

Nice to see another 83 HO around.... Adam - What kinda shape is yours in?? Do you still have the original L69, air cleaner and everything??

 

My 1985 Trans Am with the 305HO was fairly light. It had A/C, WS6, Rear Defog and Sub woofer in it. It weighed in at 3330 lbs with the 16 inch cross lace wheels. (Manual locks, Manual windows, manual mirrors).

With the timing advanced, slight carb rejeting and flowmaster exhaust the car ran the 1/4 mile in 14.9 @91 mph. I would run it with premium unleaded. I read in one of the road tests back then these engines were rated at 190 hp, but when run with high octaine the computer would advance until knock was detected.

I agree the gearing on these cars was perfect. With the 3.70 rear gear (Borg Warner) it seemed happy in all of the gears and would pull to 6000 rpm all day.

Dave

 

oh and for the record (air adam...), the autos could be had with 3.73's, and in combo with the 700's low first gear, it pulls hard out of the hole, but then it shifts into second which is drastically higher. Thats where i think the t5 has the bigger advantage it the spacing between gears keeps you in a better sweet spot of the engine.

 

3.73 and 700r4 first gear and HO or CFI 305 makes for fast lil F body, its great 3.08 sucks

 

I have a 83 HO, 35k miles. Looks PERFECT minus 1 little scratch some idiot did because he didn't get it at the auction. But I think it was hit in the front. Overspray in engine compartment, mechanical fan, and Carfax has a "record on file". Hmmmm. But it looks REAL GOOD. From the outside I don't believe it was touched.

 

Don't forget the 83 had a mechanical clutch and the 84 had the hydraulic. The mechanical clutch probably is a better performing clutch, but more wear. I think the 83 would outrun an 84 by a little. I knew someone that had a 84 Z-28 new with the 700r4 and it had 3.73's in the back and it was quicker than the Mustangs of the same year.