You pay your money for the privilege of owning an LT1. My car is much quicker than an LT1.......but worth less because it's not an LT1. I'm also quicker than an L88......but it also costs much more than my car and looks exactly like mine. You're buying the car, not the horsepower.

 

Chassis dyno's can be real heart breakers. Some give better numbers than others. As I under stand autos RWHP will be about 20% less than crank HP. Sticks about 15%.
I kind like to chuckle when I'm walking around car shows and the car owner says the engine is 500 HP. I always ask was it dynoed? 9 out of 10 times is no but that's what the engine builder said.
For me on a project car that isn't like an LT1 the engine is one my least concerns. I'm looking for rust. Looking for frame damage. Looking for poor repair work.

 

I don’t know why a manual trans would be anymore h.p. In your example above?

I too estimate h.p. when I have an engine rebuilt based on what the original factory rating and what upgrades I make, it’s not rocket science.
As an example it you build a 383 with aluminum heads and a solid lifter 1970 speced LT1 cam you can pretty much depend on about 400 h.p. flywheel rated. If you add headers add another 25 h.p. How do I arrive at these numbers? Well. If the factory rated a 1965 327 F.I. at 375 h.p then the extra cubes of the 383 and the much better breathing heads and basically the same cam it’s not hard to come up with 400 h.p.

 

195 hp at the rear? Well I guess the hp made is tied to the condition of the engine. The LT1 of 1971 had lower compression than the same engine from 1970, it was also lower than the 1969-1970 L46 engines. If the engine has bad valves or blow by, it won't perform up to potential. I believe Motor Trend test of 1970 had the LT1 running a 14.3, the L46 running a 14.4 and the base engine running in the low 15s. I think the later tests had the L82 engined Vettes of the late 70s running in the high 15s for the quarter.

 

Dyno vs Time Slip
Chrome Bumper vs Urethane Bumper
Automatic vs Standard
Modded Cars vs Stock

Enjoy what you have or buy something that you will enjoy. Never mind what he or she has.

Peace.

 

A manual trans has a higher efficiency than an auto trans. A clutch transfers more of the engines energy than a torque converter does. Result is higher wheel horse power from manual than autos.

 

LT1 was an option that commands the money and makes the 70-72 LT1 an investment that wont decrease in value...very few rubber bumper cars can say this...maybe the special editions some day but not currently. IF you want more fun out of a car all you need is a high performance tune and change the rear gear ratio and run off the torque. All of us that arent racing and getting your motor above 5200 rpm will never see or feel any of the engines HP...below that is all torque

"dynos has far fewer OUTSIDE variables to impact the results" Dynos are easy to trick and change with temperatures internal and external to the motor and different brands give different numbers to the same car if you wanted to compare. You arent going to lie about a cars weight, its top speed and the time it takes to get down the track. Given that the driver can be a variable but the top speed wont change. BUt its a real world number. I couldnt keep my tires from spinning and my best until I called it a night was 13 flat at 108 mph...most cars the same weight at that speed are 12 second cars and using that info I can get a very good idea of the horsepower to the ground. The horsepower number isnt going to be as accurate as a dyno but its more of a real world number given that its in the car in the real word moving under its own power. YOu can only get to a certain speed in a given distance with horsepower and torque and its a set number
Good builders can build a car and know what it should be on the dyno..They have done so many and repeat the same specs its pretty easy to know now a days. But the percentage loss through the drivetrain is a fallacy. I wouldnt go around saying that because it makes you look foolish if you think about it. If I take a pinto and put a 200 hp motor in it and it puts 120hp to the ground thats a 40% loss. If I through an 800hp motor in that same car you are saying that its going to only put 480 hp to the ground.......any given drive train is only going to cost "x" amount of horsepower. The only way to get that number for your car is get a engine dyno number and then a chassis number dyno and you will see what your drive train eats for HP....the only accurate way...period..
If you had the time and the money you could buy and test 50 to 100 muncies and see if the numbers are close enough to say a muncie will always eat X amount of power. Then get 100 Corvette rear ends with the same gear ratios and do the same...then trough in different ratios and see if it changes and build a library of losses. Which would help everyone but no one is going to do

 

your talking about the convertor slippage and you may get a higher number on a dyno by single digit percentages but you will never beat a car with the same power and a good auto trans...

 

it is infact a percentage, not a set number. Read about rotational inertia and acceleration losses.
It should make sense when you think about it, the faster a gearbox is accelerated, the larger the losses.
a gearbox accelerated to X speed in 10 seconds takes a certain amount of energy
the same gearbox accelerated to X speed in 5 seconds, by your logic would take exactly twice the energy, but in reality, it takes MORE than twice. The faster the rate of acceleration the larger the losses.
this is all because angular velocity is a factor in frictional force.

 

Sounds like the engine in your friends car needs some looking at (it is 50 years old after all),

I would start with a good old fashioned tune up - first off - shoot a can or two of carb cleaner spray through the carb - then put in new points, plugs, wires, cap and rotor. Then verify both the static ignition timing and verify that the centrifugal advance in the distributor is coming in at the right time, and that all the timing is in by say 3,700 RPM. (I say to do the carb cleaner before changing plugs because some of the deposits that the carb cleaner removes can end up on the plugs.)

Does the car now feel faster ?? If not - it's probably worthwhile to do a compression test and see what the internal condition of the engine is. A carb rebuild may be in order, and I would also check valve clearance.

That engine SHOULD make at least 300 HP on a chassis dyno.

 

That makes zero sense. If I accelerate a 500 hp motor in a short amount of time i wont go as fast as if I accelerate Slower and longer. So if i accelerate at 10 seconds to WOT i would only get to say 80% of my horsepower to the ground. But if i accelerate say over60 seconds i could get 90% of my horsepower to the ground. .........you kill your own theory with two opposing statements. It cant be a percentage if it changes with acceleration. You must be an engineer or a pilot

 

I compromised. My 1973 has both.

 

If the value is based on the fact that some men want something only because other men want it and not because of styling differences, that definitely is a weakness and a sin upon their character. The 63 split window comes to mind.

For me the fact that rubber bumper cars are the product of government regulation and not the styling studio, ruins them for those of us that don't like to be told what to do by bureaucrats. They have an almost perfect record for destroying everything they touch, we see that in the 1973 model year.

 

I am a chrome bumper car owner ('69 vert), but I also love the 80-82 models - any bubble window C3 for that matter, so 78-82, but I prefer the 80-82 MY because of the more aggressive front and rear bumpers. That doesn't mean that I hate the mid years, but it's just my preference. There are mid c3 gen folks here that don't like the bubble window years either...

I also own a C4 vert, and talk about hate. That car gets bashed by Corvette owners these days, but I love it all the same. I imagine more than a few rubber bumper C3 owners would and do turn their noses up to the C4 gen as well, so there is plenty of disdain to go around. I would like to have an 80-82 to complete the collection, but just don't have room for another one - HAHA.

I myself don't have much care for the C5 gen, despite it being superior in just about every aspect to the C4 (and certainly the C3), but I don't like the styling... It looks like they stretched and flattened a C4 Corvette to get that design, however I do recognize its merits. It obtained a level of performance unmatched by previous gens, and per usual, pushed the envelope. C5's, like the C4's are a tremendous bargain these days because of the hate...

I suspect that many baby boomers will gravitate to the C2 design and prefer it over the C3. Every generation will have its preference for whatever Corvette generation they favor (and year within said generation). While I do like the styling of the C2, I grew up with early C3s, and that's what I gravitate toward. I suppose the C4 and C5 would have been more aligned with my age group, but the early C3 cars is what my dad always had back when I was young and impressionable.

Growing up with Corvettes, and having them for a majority of my adult life, I have rather concrete feelings about all the other gen Corvettes as well, but don't feel like writing a book discussing my opinions on each of them - nor would members likely care to read it. I'll just say that the C3 is my jam. It's my favorite gen... Someone made an ice cream reference earlier which sums it up nicely - although some prefer vanilla over chocolate, we all like ice cream!

 

195 HP. I believe it. But then you make it part of the equation for value which I am not sure that works like it used too. I put my 75 308GT4 on a dyno after I rebuilt the engine. I got 200 HP at the rear wheels! Ha ha. It sucks but...when you drive that car with the sounds and handling, you think you are in a race car. Just don't get into a race at a stoplight. When I built the Vette I was shooting for 300 HP. Too much work to try for anything more. My wife's Tesla ruined it for me to try and make a fast car. Why bother? Our old cool cars are just that. Cool. And I think the value will hold up regardless of HP.

 

Good info...I had an issue with my GTO back in the day suddenly going flat off the line when I got back from a deployment and I found the distributor advance had seized so it was locked out and wouldnt respond to mechanical or vacuum advnace

 

If you're screwing around during a pass, yes a time slip can lie. That said, MPH calculated over an 1/8 or 1/4 mile knowing the weight of the vehicle is a far more accurate measure of power than a dyno.

 

EXACTLY.

 

Why did they dyno it at 5300 rpms? It has the same came as a 1970 and the factory redline was 6000 rpms. Sounds like he left some h.p. on the table.

 

If it was a solid lifter it would max somewhere in the 6500 range...torque and HP cross at 5200 so it wasnt even close to total power. I would like to see the curves. If HP was falling off at 5300 and it was hydraulic you had some lifter issues