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Engine & DrivetrainDiscussions about the engine and drivetrain of your vehicle.
This is a discussion thread titled "How does the performance of the 4.7L i-force V8 compare to the 5.3L LS1-based Chevy?", within the Engine & Drivetrain forum, part of the Technical & Vehicle Assistance Forums category.
One thing you didn't mention which I'd like your thoughts on, is the fact that the Toy 4.7 is a twin-cammer. Since you've had real-world experience with the GM V8s and the DOHC Toy V8, how would you compare the two engines in that area? Does a DOHC V8 perform much better than a std V8? Doesn't the DOHC V8 have the ability to rev higher? You touched on that in your post. Thanks again.
Originally posted by EZ2BME Thanks for the great post, v8Toilet.
One thing you didn't mention which I'd like your thoughts on, is the fact that the Toy 4.7 is a twin-cammer. Since you've had real-world experience with the GM V8s and the DOHC Toy V8, how would you compare the two engines in that area? Does a DOHC V8 perform much better than a std V8? Doesn't the DOHC V8 have the ability to rev higher? You touched on that in your post. Thanks again.
Yes a DOHC engine has the ability to rev higher than a pushrod motor but in the I-force vs. Vortec case the Vortec has a higher reline. This has more to do with the camshaft, induction and exhaust systems. With street engines were most engines don’t rev past 6000 RPM that’s not important especially on a Truck. A 4-valve DOHC engine has a potentially higher RPM limit because it is less prone to valve float with smaller lighter valves and better breathing characteristics. The 4 -valve configuration has more surface area than you could get from two larger valves in the same sized bore. DOHC engines also tend to be smoother. As you already know a 4-valve engine can make more torque than a two-valve engine in street applications. You can see this when you compare the I-force 4.7-liter v8 to the Vortec 4.8-liter v8. Even with the Chevy’s slight displacement advantage the I-force v8 makes more torque. The Vortec makes 285-ft. lbs. of torque @ 4000 RPM while the I-force makes 315-ft. lbs. of torque @ 3400 RPM. That’s only 10-ft. lbs. less than the bigger Vortec 5.3-liter engine. The Vortec 5.3 makes 325-ft. lbs. of torque @ 4000 RPM.
The Vortec 4.8 and 5.3 have a 6000 RPM redline while the I-force 4.7 has a 5400-RPM redline. Like I said before though the Tundra visits 4000 RPM without you knowing it while to get the Vortec to visit 4000 RPM you have to really gas it and the Transmission seems to hold it back in comparison to my Toyota anyway. You also know you’re at 4000 RPM in the Chevy! The Vortec motors are noisier and more course sounding compared to the I-force motor in the upper rpm ranges but the Vortec motors are way better than the previous generation Chevy motors. The I-force motor is butter smooth and it loves to rev. The Tundra engine is smoother in the upper RPM ranges than the Vortec motors are. I'm not saying the Vortec motors are not smooth, they are smooth motors too. It’s a very subjective and opinionated subject. Without hard numbers all you really have is my opinion.
I don't want to sound biased towards the Tundra just because I own one. I actually really like the Chevy trucks too and I enjoy driving both of them for different reasons. For one the Chevy is a better truck for hauling bigger heavier loads than the Toyota. It’s roomier inside too and it even takes large bumps better than my Toyota does despite what the magazines say. My Tundra will bottom out over large bumps because of its limited suspension travel. My Tundra is more maneuverable though because of its slightly smaller size and is more fun to drive in everyday driving. It feels light on its feat compared to the Chevy and the steering is more precise on the Toyota. I like the brake feel better on the Toyota but the Chevy brakes feel more fade resistant than my Toyota brakes do in heavy stop and go traffic. The Toyota brakes bite better and stop the truck in less time without as much pedal effort when they don’t fade, which isn’t often.
Its hard to put it in words, you just have to test drive them both and find out for yourself. When I was looking for a truck I almost bought a Silvorado. If it weren’t for the dealer trying to stiff me I would probably be driving a Chevy right now. Someone suggested I try out the Tundra and one test drive is all it took.
There’s no doubt about one thing; the DOHC 4-valve design of the I-force v8 definitely has an advantage over the pushrod design of the Vortec motors. They just breathe better and therefore make more power. If Toyota made a 5.3-liter DOHC I-force v8 and put it in a similarly sized truck as the Silvorado the Toyota would out pull, out accelerate, and out do that Vortec 5.3-liter engine easily. GM chooses to build pushrod motors because they are much cheaper to build. You only have one camshaft instead of four. You only have 16-valves instead of 32. The heads are less complicated on a pushrod motor. You only need a small chain to drive the camshaft on a pushrod motor, while you need a bigger more complicated belt or chain to drive the four camshafts on the DOHC v8 with things like idler pulleys too. A DOHC v8 is also larger than a pushrod motor of the same displacement making it harder to fit it in an engine bay.
Did you know the reason why GM built a straight DHOC 4-valve six cylinder engine instead of building a DOHC 4-valve v6 configuration? It was because of cost. With a straight inline design you don’t have as many parts and it’s less complicated too. For example you only have two camshafts instead of four. You only have one head instead of two. This enabled GM to put the money into technologies like variable exhaust valve timing though and an inline 6-cylinder engine is also smoother than a v6 engine is.
Just think of the ZR1 Corvette vs. the new LS1 Corvette motors; both are 350 cubic inches I believe. The ZR1 made 375 horsepower and 370-ft. lbs. of torque over ten years ago and it love to rev. The 2003 LS1 makes 350 horsepower and 360-ft. lbs. of torque and the LS6, makes 405 horsepower and 400-ft. lbs. of torque. Imagine with today’s technology how much power the Corvette could have if Chevy made a 4-valve DOHC version of the LS6 motor.
You know, when I've driven in Chevy trucks I've been pretty happy with their performance. As a "truck" they have a lot of advantages. The 0-60 numbers change in favor of Chevy once you start to load down the bed of the truck.
The Tundra is more fun to drive because it's sportier, but if I were going to buy a truck for work, I'd probably consider the Chevy over a Tundra.
The advantage that Toyota has, though, is reliability.
Alan
Quote:
Originally posted by v8Toilet
Yes a DOHC engine has the ability to rev higher than a pushrod motor but in the I-force vs. Vortec case the Vortec has a higher reline. This has more to do with the camshaft, induction and exhaust systems. With street engines were most engines don’t rev past 6000 RPM that’s not important especially on a Truck. A 4-valve DOHC engine has a potentially higher RPM limit because it is less prone to valve float with smaller lighter valves and better breathing characteristics. The 4 -valve configuration has more surface area than you could get from two larger valves in the same sized bore. DOHC engines also tend to be smoother. As you already know a 4-valve engine can make more torque than a two-valve engine in street applications. You can see this when you compare the I-force 4.7-liter v8 to the Vortec 4.8-liter v8. Even with the Chevy’s slight displacement advantage the I-force v8 makes more torque. The Vortec makes 285-ft. lbs. of torque @ 4000 RPM while the I-force makes 315-ft. lbs. of torque @ 3400 RPM. That’s only 10-ft. lbs. less than the bigger Vortec 5.3-liter engine. The Vortec 5.3 makes 325-ft. lbs. of torque @ 4000 RPM.
The Vortec 4.8 and 5.3 have a 6000 RPM redline while the I-force 4.7 has a 5400-RPM redline. Like I said before though the Tundra visits 4000 RPM without you knowing it while to get the Vortec to visit 4000 RPM you have to really gas it and the Transmission seems to hold it back in comparison the my Toyota anyway. You also know you’re at 4000 RPM in the Chevy! The Vortec motors are noisier and more course sounding compared to the I-force motor in the upper rpm ranges but the Vortec motors are way better than the previous generation Chevy motors. The I-force motor is butter smooth and it loves to rev. The Tundra engine is smoother in the upper RPM ranges than the Vortec motors are. I'm not saying the Vortec motors are not smooth, they are smooth motors too. It’s a very subjective and opinionated subject. Without hard numbers all you really have is my opinion.
I don't want to sound biased towards the Tundra just because I own one. I actually really like the Chevy trucks too and I enjoy driving both of them for different reasons. For one the Chevy is a better truck for hauling bigger heavier loads than the Toyota. It’s roomier inside too and it even takes large bumps better than my Toyota does despite what the magazines say. My Tundra will bottom out over large bumps because of its limited suspension travel. My Tundra is more maneuverable though because of its slightly smaller size and is more fun to drive in everyday driving. It feels light on its feat compared to the Chevy and the steering is more precise on the Toyota. I like the brake feel better on the Toyota but the Chevy brakes feel more fade resistant than my Toyota brakes do in heavy stop and go traffic. The Toyota brakes bite better and stop the truck in less time without as much pedal effort when they don’t fade, which isn’t often.
Its hard to put it in words, you just have to test drive them both and find out for yourself. When I was looking for a truck I almost bought a Silvorado. If it weren’t for the dealer trying to stiff me I would probably be driving a Chevy right now. Someone suggested I try out the Tundra and one test drive is all it took.
There’s no doubt about one thing; the DOHC 4-valve design of the I-force v8 definitely has an advantage over the pushrod design of the Vortec motors. They just breathe better and therefore make more power. If Toyota made a 5.3-liter DOHC I-force v8 and put it in a similarly sized truck as the Silvorado the Toyota would out pull, out accelerate, and out do that Vortec 5.3-liter engine easily. GM chooses to build pushrod motors because they are much cheaper to build. You only have one camshaft instead of four. You only have 16-valves instead of 32. The heads are less complicated on a pushrod motor. You only need a small chain to drive the camshaft on a pushrod motor, while you need a bigger more complicated belt of chain to drive the four camshafts on the DOHC v8 with things like idler pulleys too. A DOHC v8 is also larger than a pushrod motor of the same displacement making it harder to fit it in an engine bay.
Did you know the reason why GM built a straight DHOC 4-valve six cylinder engine instead of building a DOHC 4-valve v6 configuration was because of cost? With a straight inline design you don’t have as many parts and it’s less complicated too. For example you only have two camshafts instead of four. You only have one head instead of two. This enabled GM to put the money into technologies like variable exhaust valve timing though and an inline 6-silinder engine is also smoother than a v6 engine is.
Just think of the ZR1 Corvette vs. the new LS1 Corvette motors; both are 350 cubic inches I believe. The LS1 made 375 horsepower and 370-ft. lbs. of torque over ten years ago and it love to rev. The 2003 LS1 makes 350 horsepower and 360-ft. lbs. of torque and the LS6, makes 405 horsepower and 400-ft. lbs. of torque. Imagine with today’s technology how much power the Corvette could have if Chevy made a 4-valve DOHC version of the LS6 motor.
Did you know the reason why GM built a straight DHOC 4-valve six cylinder engine instead of building a DOHC 4-valve v6 configuration? It was because of cost. With a straight inline design you don’t have as many parts and it’s less complicated too. For example you only have two camshafts instead of four. You only have one head instead of two. This enabled GM to put the money into technologies like variable exhaust valve timing though and an inline 6-silinder engine is also smoother than a v6 engine is.
Just think of the ZR1 Corvette vs. the new LS1 Corvette motors; both are 350 cubic inches I believe. The LS1 made 375 horsepower and 370-ft. lbs. of torque over ten years ago and it love to rev. The 2003 LS1 makes 350 horsepower and 360-ft. lbs. of torque and the LS6, makes 405 horsepower and 400-ft. lbs. of torque. Imagine with today’s technology how much power the Corvette could have if Chevy made a 4-valve DOHC version of the LS6 motor.
Yes, I was surprised that GM chose to reintroduce the straight-6 configuration in the Trailblazer/Envoy SUVs....and at 270HP, although I don't recall the torque numbers. If these engines hold up, great...if not, then this is just another example of the General keeping production costs low at the expense of quality.
As for the Corvette engines....I have the chevy.com corvette page open in a separate window to look at engine specs. Man!!..the LS6 is capable of 0-60 in under 4 (four) seconds!!......unbelievable for a production 'vette!!!
GM does have a DOHC V8 in its Cadillac STS and Eldorado, so I'm surprised they haven't matched a version of that technology to a high-tech ride like the 'vette now that we're in the Y2K era. Pushrod seems archaic in a 'vette these days, in spite of awesome specs.
I had a '94 Cobra with a 5.0 rated at 240hp....now the Cobra has a DOHC 4.6 rated at 390hp@6000rpm with 390ftlb torque@3500rpm ahhhh...yes..I think it's great to put a DOHC v8 in a muscle car. Perhaps pushrod technology killed the f-bods from GM...so now we no longer have the Z28, SS or T/A and WS-6, which gave a guy the most bang for the buck!!
Back to the trucks.....I think it's great that Toyota has a DOHC v8 in the Tundra and wonder how long it'll take the Big 3 to do the same with its products. I too, came awfully close to buying domestic....already had a tricked-out SCrew with a 5.4 picked out, but the Tundra test-drive at the finish line of a one year research period ended my near-purchase of a Ford SCrew. Happy to say I'm extremely happy with my decision one year later.
Thanks again, v8Toilet for a very informative post.
GM has some new DOHC 4 cylinders called ECOTEC. The one in the attached picture runs the 1/4 mile in the low 8's. There are others that are faster. This one is a turbocharged 2.0 liter. I saw a rear drive 2.2 version go low 7's at about 190 MPH. That's like 1200 HP out of about 130 cubic inches. I think they said it's the world's fastest 4 cylinder powered drag car. Not too shabby for a cheby.
Dude
__________________ ADDING POWER HAS NEVER BEEN SO FAST!
Originally posted by Dude Boy GM has some new DOHC 4 cylinders called ECOTEC. The one in the attached picture runs the 1/4 mile in the low 8's. There are others that are faster. This one is a turbocharged 2.0 liter. I saw a rear drive 2.2 version go low 7's at about 190 MPH. That's like 1200 HP out of about 130 cubic inches. I think they said it's the world's fastest 4 cylinder powered drag car. Not too shabby for a cheby.
Dude
I think GM has a ways to go before they catch up to Honda/Toyota DOHC fours in their production cars. I had a '98 Prelude with a 2.2 DOHC VTec 200HP/5spd. What a screamer for a
little four-banger. The Integra TypeR (1.8, I think) is another example of an outstanding, high-revving rocket from Japan.
Toyota's got some solid DOHC fours in the Celica line, but not as performance oriented as Honda/Acura.
The example you give is a modified engine- for- race version. Heck, Honda and Toyota have the same thing, but in Formula 1 race cars. I don't know if Honda/Toyota is into modified stock car racing, though, like the Cavalier you point out. Badazz pic, where'd you get it?
I don't know if Honda/Toyota is into modified stock car racing, though, like the Cavalier you point out. Badazz pic, where'd you get it?
I took the picture at the drags last weekend. There were plenty of modified Toyotas and Hondas there also. The AEM Honda picture that I've attached below was also running in the 8's. I didn't like it, but the GM Quad Four was also a pretty hot engine in it's day.
Dude
__________________ ADDING POWER HAS NEVER BEEN SO FAST!
Originally posted by Dude Boy Probably getting off topic here a bit, but below is an attached file showing the AEM Honda's VTEC engine.
Wow!!! Great pics.....did you have some sort of pit pass to get those closeups? Outstanding views!
BTW....do you by chance have a soundclip of your Bassani's? Hover is thinking of getting catbacks, but was trying to listen to sound. I think he prefers a personal soundcheck, but soundclips are what I used before getting my Borlas. I considered the Bassani's, they were a little too steep for me.
Originally posted by akauth Great info V8Toilet. The 0-60 numbers change in favor of Chevy once you start to load down the bed of the truck.
Actually there was a comparison between the 2002 Chevy HD with the 6.0-liter engine, the 2002 Toyota limited, the 2001 Ford with the 5.4-liter engine and the 2002 Dodge with the 4.7-liter engine in Motor trend. The Toyota still out accelerated them with a 1000 lb. load in the back and tied the Dodge for the shortest stopping distances.
The 0-60 times unloaded, loaded with 1000 lbs. were,
Toyota 8.2/10
Ford 9.0/10.6
Chevy 9.1/10.3
Dodge 9.6/11.3
#1- To those comparing 5.3 Tahoes to 4.7 Tundras... that's apples to oranges. Load your Tundra up with an extra thousand pounds in the bed, and attach another 700 pound trailer to the back, and then you'll get a better feel. Tahoes weigh a LOT more than Silverados.
#2- V8Toilet... was it just me, or are the work trucks you are comparing to your Tundra 4x4, while the Tundra is 4x2 (a few hundred pounds lighter)?
#3- EZ2BME- The Cobra doesn't have 390 horsepower just because it went DOHC... it also has about a hundred other tweaks including a supercharger. The push-rod 94-95 Cobra was rated at 240 horsepower... most people dyno them to be around 250. The 96 Cobra was the first year they went DOHC, and the power went up to a rating of 305, although people usually dyno them around 280-290 up until the 2001 model year when ford finally fixed some things. So the whole DOHC thing really only netted an extra 30-40 horsepower... while also losing some torque in the process... the Cobra motor is pretty wicked but it just doesn't feel very ballsy while driving normally.
Not saying DOHC isn't cool and all, just saying it didn't singlehandedly make the Cobra gain 150 horsepower.
Also- you were wondering why the vette isn't going DOHC? Many reasons... but probably the foremost is the fact that within 3 years from now the Z06 model with feature a camless motor with electromagnetically actuated valves, and inherently displacement on demand, as well. The 'regular' vette will follow suit within a year or two of that. They are pulling 350-420 horsepower out of the pushrod motors, getting 20-33 MPG, and respectable reliability... why mess with success unless you have something revolutionary to replace it with. That's always been Chevy's way of doing the vette.
Wow!!! Great pics.....did you have some sort of pit pass to get those closeups? Outstanding views!
BTW....do you by chance have a soundclip of your Bassani's? Hover is thinking of getting catbacks, but was trying to listen to sound. I think he prefers a personal soundcheck, but soundclips are what I used before getting my Borlas. I considered the Bassani's, they were a little too steep for me.
No pit pass needed for NHRA events that I know of. You can chat with the drivers and look over their shoulders as they work on their motors, etc. The Bassani sound clips on Hover's site are of my exhaust. I paid $485 including shipping, but I think they've gone up since then.
Duce
__________________ ADDING POWER HAS NEVER BEEN SO FAST!
Originally posted by Threxx #1- To those comparing 5.3 Tahoes to 4.7 Tundras... that's apples to oranges. Load your Tundra up with an extra thousand pounds in the bed, and attach another 700 pound trailer to the back, and then you'll get a better feel. Tahoes weigh a LOT more than Silverados.
Let's see, the Tundra 4WD EX CAB I'm driving weighs in at 4518 lbs according to dealer specs. It has 245 HP and 315 Ft/Lbs of Torque. The 4WD Tahoe weighs in at 5269 Lbs but with 285 Horsepower and 325 Ft/Lbs of Torque. With a weight difference of 700 LBS but with the extra 40 HP and most importantly 10 more ft lbs of torque, I believe these two vehicles are equally matched. I agree with you on the weight of the Silverado though. Has any one raced one?
Just a follow up to the below post. I checked the specs on the 4dr 4WD 1500 SIlverado with the 5.3. It showed its curb weight at 5112 LBS. Only 150 off from the Tahoe. If were racing Tahoes and beating them, I think it should be a good race against the Silverado.
Originally posted by Threxx
#2- V8Toilet... was it just me, or are the work trucks you are comparing to your Tundra 4x4, while the Tundra is 4x2 (a few hundred pounds lighter)?
No it was a comparison with a 4*4 Limited Tundra in Motor Trend magazine. I drive a 4*2 like I said before and the 4*2 is only .2 to .5 seconds quicker to 60 than most 4*4 Tundra's.
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