2011 Chevy Silverado

Frank Acampora

Supreme Mariner
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Jan 19, 2007
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12,004
My owners manual gives axle ratios, towing capacities etc. However nowhere in the manual is horsepower ever mentioned. Does anyone know the horsepower rating of the 5.3 flex fuel active fuel management engine? Just curious since my '99 4.3 was rated at 180
 

CVX20SPRINT

Petty Officer 1st Class
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Sep 9, 2009
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213
The auto industry seems to have come full circle.Years ago( 60's and into the 70's)the manufacturers were posting huge hp numbers for their muscle cars and then the insur companies got involved.All of a sudden you could hardly find a hp rating listed anywhere.Now with most of the 6 cylinders these days being over 300 hp and a lot of the v8's over 400 stock and the manufacturers bragging about it ,how long before the insur companies step in again and make people pay large for their large hp.

BTW If you had a 300 hp 327 ci. back in the day it was a pretty formidable motor,now a 300 hp+ 6 cylinder is the norm,not the exception.
 

NYBo

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Oct 23, 2008
Messages
7,107
The auto industry seems to have come full circle.Years ago( 60's and into the 70's)the manufacturers were posting huge hp numbers for their muscle cars and then the insur companies got involved.All of a sudden you could hardly find a hp rating listed anywhere.Now with most of the 6 cylinders these days being over 300 hp and a lot of the v8's over 400 stock and the manufacturers bragging about it ,how long before the insur companies step in again and make people pay large for their large hp.

BTW If you had a 300 hp 327 ci. back in the day it was a pretty formidable motor,now a 300 hp+ 6 cylinder is the norm,not the exception.
HP plummeted in the 70s mainly due to emissions laws and the quest for improved fuel economy due to the oil embargoes.
 

H20Rat

Vice Admiral
Joined
Mar 8, 2009
Messages
5,199
The auto industry seems to have come full circle.Years ago( 60's and into the 70's)the manufacturers were posting huge hp numbers for their muscle cars and then the insur companies got involved.All of a sudden you could hardly find a hp rating listed anywhere.Now with most of the 6 cylinders these days being over 300 hp and a lot of the v8's over 400 stock and the manufacturers bragging about it ,how long before the insur companies step in again and make people pay large for their large hp.

BTW If you had a 300 hp 327 ci. back in the day it was a pretty formidable motor,now a 300 hp+ 6 cylinder is the norm,not the exception.


Most of those vehicles were barely safe at highway speeds! If you look at any of those muscle cars, they actually had a pretty low hp/weight ratio, compared to today, and were still unsafe! Minivan's have more hp today... OPEC did far more to kill the muscle car than insurance ever did.
 

MH Hawker

Vice Admiral
Joined
Jul 13, 2011
Messages
5,516
Congratulations Frank on the new truck, I made the switch from a S 10 to a silverado all most 2 years ago and while the gas milage isnt as good its a beast for towing.
 

Saline Marina

Petty Officer 2nd Class
Joined
Sep 9, 2014
Messages
162
There are also issues surrounding how much exhaust backpressure is set on the dyno when doing an "advertised power" run. Now, it has to match the backpressure in the vehicle. Back Then I think they just ran with straight pipes essentially like a marine thru-hull exhaust. Also the "SAE Gross" horsepower involved running without the accessory drive, whereas today's power run must have the entire accessory drive operating. We must consider the effect of tetraethyl-lead from days of yore, which is a free octane gainer 3-5 points IIRC with nasty environmental cumulative damage. Easy HP to be made on a pushrod engine by cranking up the compression ratio and adding spark advance. Lots more tricks today with direct-inject, coil-on-plug ignition (to eliminate the distributor drive), oil pumps that have variable flows, piston cooling oil jets, aluminum heads to take away the knock limit with knock sensors to avoid destroying pistons.

Advertising a high horsepower today is mostly about technology with the valvetrain to allow a higher rev limit. Just produce an average amount of torque higher up the RPM scale and there is horsepower waiting for you. The classic equation is HP = TQ * RPM / 5252, with torque in foot-lbs, so you can see mathematically is a higher RPM is a multiplier.

I was involved in pushrod engine development about 20 years ago, many things are the same but obviously with new technology. The race/push for fuel economy has really opened up a lot of new additions to the classic internal combustion setup.
 

Frank Acampora

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Jan 19, 2007
Messages
12,004
Well. I'll tell you : I was impressed with this truck . Not only does it deliver 19 MPG average on long mostly highway trips (unloaded) and around 17 city driving (again unloaded ) but is has more than enough power. I was on a long straight stretch of road on a trip up to New York. I was averaging around 65 MPH. I passed another car and saw I was doing around 80. SO: I decided to see what she would do and dumped it. Well, up around 100 it still had plenty of poop and was still pulling hard BUT--the computer got excited and told me in no uncertain terms " YOU DON'T NEED TO GO ANY FASTER!. so I let it coast down. I know the truck can go faster but I don't know what gear I was in when the RPM limiter kicked in and really, I don't care. That's probably the first and last time I will feel the RPM limiter.. Towing speeds will always be down at 65 max and it does cost too much to go fast, either unloaded or towing.

At any rate, even at that high speed the ride was solid and comfortable and the wife was not giving me grief. The only two negatives I have about the truck is that the cup holders in the doors are placed so you can't get anything into them with the door closed. AND--The previous owner installed a stainless steel Magna-Flow dual exhaust catback system. Read noisy! However, I was given the original muffler and tailpipe but my mechanic said: "Why would you want to go back?" So I am keeping the Magna-Flow. Actually, I use the noise as a tool to increase mileage: When it is really noisy I know I have gotten too far into the pedal and back off a bit--it does work.
 

MH Hawker

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Jul 13, 2011
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5,516
I got mine mostly to tow with and it rides so nice i have taken it on several trips.
 
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