Peixinho

Alright... I am not sure if this should be in the tech section but I will try it here in the general section...

I am trying to better understand old tech for 60s and 70s vs 90s and 00s.

What I mean by that is that the old vettes (and many other cars) made huge horsepower numbers. I know some of these numbers were overinlfated... or maybe even under inflated... but still we were seeing easy 350-450 hp... then we had the gas crunch and emissions... and now we are putting out more efficent cars with good numbers again. For example 1997 c5 with 350 hp...

I know my question might be hard to understand but which ones are faster/make more power/with in a race. I know weight and all of that make a huge difference but I am talking if you took the same two motors and stuck them in the same car.

I was always under the impression that fuel injections was much more efficient and with computer ingnition systems that made cars even more efficient. Are the cars of today more powerful, or just more efficient.

If you took an old carberated motor from the 60s that put out 500hp and stuck it in a 1997 c5 corvette would it make the vette a lot faster? (not taking into account oversteer, understeer, weight, or actually even fitting the motor under the hood) I am speaking hypothetically.

Let me know if I am not making any sense. I am just asking how powerful the engines of the 60s and 70s really were as compared to the motors we have now. ( i know the zr1 and many others put out more than that but I am asking about the ls1 motor vs the old l88 or others from the old days)



Here is one of the reasons I am asking. I have talked with many people who tell me how easy it is to make big numbers on old carburated motors. Like my brother in law with a 79 vette. From the factory it came with around 200hp and I asked him if he ever thought about swapping in an ls1, ls6, or ls2. He said now way!!! He said he found a shop that for $2500 they could rebuild his whole motor and he would be putting out about 350hp... i said no way but I have always heard it is easy to make the old cars faster...


Ok let the teaching begin

rtpassini

fuel injection doesnt make any more power. ive seen old carb motors tested with a FI setup and it actually made a little less hp.

so that isnt a factor. thats more of an efficient gas mileage type thing.

i dont think one is better than the other. these motors are built with newer technology, but that doesnt necessarily mean they are a better platform (stock for stock)

I had a 6.6 liter from 1967 in my 1980 trans am. it was a huge motor, but was also rated EXTREMELY low due to emissions and things like a/c, power steering, etc etc. but what is was rated wasnt what it could actually put out.

and it also depends what motors you are talking about. you could have an old chevy motor rebuilt for that. I've seen 3-350 hp pontiac motors built by reputable shops go in the 3500 dollar range.

it wouldnt be faster putting an old motor into something like a c5 platform just because of the materials that these newer motors are made out of. less overheating issues and other things.

Peixinho

ok... interesting... I always thought that fuel injection made more horspower... for a couple of reasons...

I used to have a 1990 Honda Prelude. It came with two motors for that year. Same block, cams, everything except one of fuel injected and one was dual carbs. The fuel injected motor made about 25 mor hp... (155 vs 130)

Next example... we had an old IDI turbo ford diesel that was slow and made little horsepower and torque... when the feul injected powerstroke came out it made way more hp and torque...

Also what about the tuned port injection vs throttle body of the 80s???

rtpassini

fuel delivery plays a minor role. Cam profiles are probably different. I had a prelude motor that I swapp ed into a different honda. Mine was .1 liters bigger but made less hp than my buddies that he put in due to slightly different cams and other variables

Peixinho

my wife and I were thinking about starting to mod the vette...

well the most bang for you buck would be Header, cam, intake, exhaust, and tune. (maybe even head swap)

or...

we would go with a super charger...

Either one of those options would hopfully gain between 100-150hp and would cost between 5000 and 7000 dollars...

I could not believe he could get his whole motor rebuilt and gain 150 hp for 2500 dollars... (its just not fair ha ha)

slowtealz28

He could MAYBE get his motor rebuilt for that much, but it won't touch a C5 with a blower, I promise you that. BTW, a blower done right will be more than 7 grand.

tony75A

I believe that the SAE testing criteria changed within the last few years as to how engines from the factory are rated. I believe in the past the companies were allowed to remove the power steering, emission controls and add more free flowing exhaust to establish their advertised power and fuel economy. Now there are more stringent guidelines as to how many tweaks can be made.

Fuel injection can bring in more timing so there is less unused power left on the table. Let your brother in law waste as much as he wants on his old small block. He may build it to have more power and cheaper, but will it idle smooth and not overheat? Will it run pump gas? The ls1 is a much better engine all around. He is probably just scared of wiring.

cor28vettes

Nearly all cars for 1971 had engines w/lower compression that allowed them to run on unleaded gas. Power ratings were to switch from 'gross' to lower 'net' ratings for '72. The 1970's stillborn LS7 454 finally materialized w/lower compression as the LS6, producing 425 gross HP, or 325 by the new net rating.
source: Corvette America's Sports Car


With the exception of RPO LS6, 1971 engines were detuned variants of 1970 engines. GM'S intention in reducing octane requirements to 91 (research) in 1971 was to give oil companies phase-in time for the unleaded fuels needed for catalytic converters still four years away.

That '71 LS6 w/425HP was designed to operate on low-lead fuel. Good luck finding one. Only 188 were produced. Biggest (new) HP rating in 72 Vettes was the 270HP 454.
source: The Genuine Corvette Black Book

jcgunn

Old School: Fuel + Air = Horsepower...but not efficiency

C5/C6 Corvette: Fuel + Air + Computer + Gears = Horsepower and Efficiency (when right foot allows)...and some more complicated MX

themonk

'97's had 345 bhp, not until 2001 did they have 350.

GM Fan

Keep in mind prior to 71 or 72 cars were rated in "Gross" hp, in other words the engine tested without all the accessories present, often w/ long tube headers/no mufflers, and non-stock aircleaner/intake and tune setups. They would lose something like 50-100hp moving to "Net" hp ratings of today. So numbers were "inflated" vs cars of today, but some cars were deliberately underrated as well, so it isn't always clear cut.

All but the meanest and baddest factory hotrods when truly factory stock would not be able to outpower a bone dead stock LS1... Horsepower wise at least, some of those beasts were low end torque monsters...

Consider a LS1 rated in gross hp ratings would be north of 400hp most likely.

I find chassis dyno shootouts that include older muscle cars very interesting. I'd love to see a fairly stock 375hp 396 tested, my father talks his late model year 67 Camaro SS 375hp 396 up something fierce...



LS6 454 Chevelle and 427 Yenko Camaro dyno tested:
http://www.superchevy.com/technical/...ars/index.html

This test with a LS1 GTO vs some older GTOs was pretty interesting:
http://www.highperformancepontiac.co...out/index.html



Kind of eye opening as the first article put it. A LS3 would put those to shame, a LS7 would be in a whole nother world. Of course if you uncork those beasts up and ditch the crappy exhaust manifolds, etc, it will get a lot closer.

76 VETTE

I think the 60s and 70s horsepower was gauged at the fly wheel.Todays monsters are gauged at the rear wheels.

sean.b

you're comparing engines instead of the era's both are from. you can easily make a 1st gen small block fast these days with the abundance of parts and technology that are available today that wasnt available 60 years ago. a couple of minor examples would be we dont have to find 400 cranks to create a 383 - they're made for it. we dont have to find compatible head swaps from all OEM parts, instead we have purpose built heads you can order, etc.

but if you've never gone through the fun of learning and tuning a carb (im 29 and had to look for several days to find somebody to help with this on my cars!) knowing what you're doing there is nothing at all like opening a laptop and having graphs, pulse width modifications, etc. i guess the AFR principles are the same, but thats about where it stops.

there were studies done comparing efficiency, on one of the bigger performance/racing magazines, and they were able to get mileage respectably closer to fuel injection than most would think.. but carbs are carbs. when the season/temperatures change, your carb doesnt, your ECM does. when you're detonating, your carb doesnt change. your knock sensor/ECM will.

so its not that the change was made just for power, or just for efficiency (although its far easier to get both with gen 4 stuff). its just better!

BUT.. my Nova sounds like mad angry sex when its cranked. just saying.

RetiredSFC 97

As has been said. Gross versus net. IIRC I read an article that stated there were a few reasons for this.

back in the day HP numbers, and still are, a big deal. So the manufacturers would always measure numbers at the flywheel. Some were exaggerated and some were not. with the advent of the green weenies and the whining of insurance companies they changed to net HP. As the emission requirements got going strong it reduced the numbers greatly. Unleaded fuel yaddy yadda, and an assortment of other things.

you could still make them go but you were putting in gears, cams, headers and an assortment of other things to get the compression back to producing HP again. But this was also mainly for drag strip racing. You still couldn't get the numbers then, we have today, for road course driving.

So folks like it or not the C4, and the technology that came with them, put us back in the game. The Crossfire made a huge difference, then the L98, for it's time was a beast. The LT1, the LT4 and the big daddy of them all the LT5 made owning and driving a vette a performance car and not an old man's grocery getter and young chick magnet.

You can still take an old 396 and make it fast but we have the technology now we didn't have then.

sean.b

oh, and i just want to throw out if you've never replaced the springs in a distributor, you dont appreciate the sbc under your hoods now!

slowtealz28

I had a run in with a 70's? Duster one day, his car was fully rebuilt etc. This was in mexico. My car at the time had headers and a messed up trans, was running 12.8@112. We proceeded to run and I no lie put about 2 bus lengths on him in the 1/4 mile. He couldn't believe it. It sounded fast, but that Duster got DUSTED.

dougbfresh

Why are you trying to compare old/new HP numbers anyway? Crate motors as well as packages from companies like Edelbrock can make 350+ HP on a carbed engine easy. You'll never get the mileage or overall performance out of a carb'ed engine. $2500 in the old 350 could get him to 350 HP (heads, cam, intake).

02z06dave

cars today are not rated from the factory at the rear wheels.

RetiredSFC 97

I started to comment on that but let it go.

My LS1 Dynoed at 308. Tons of threads about RWHP and advertised HP on here.

RetiredSFC 97

SAE gross powerPrior to the 1972 model year, American automakers rated and advertised their engines in brake horsepower (bhp), frequently referred to as SAE gross horsepower, because it was measured in accord with the protocols defined in SAE standards J245 and J1995. As with other brake horsepower test protocols, SAE gross hp was measured using a stock test engine, generally running with few belt-driven accessories and sometimes fitted with long tube (test headers) in lieu of the OEM exhaust manifolds. The atmospheric correction standards for barometric pressure, humidity and temperature for testing were relatively idealistic.

[edit] SAE net powerIn the United States, the term bhp fell into disuse in 1971-72, as automakers began to quote power in terms of SAE net horsepower in accord with SAE standard J1349. Like SAE gross and other brake horsepower protocols, SAE Net hp is measured at the engine's crankshaft, and so does not account for transmission losses. However, the SAE net power testing protocol calls for standard production-type belt-driven accessories, air cleaner, emission controls, exhaust system, and other power-consuming accessories. This produces ratings in closer alignment with the power produced by the engine as it is actually configured and sold.