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Discussion Starter · #1 ·
I am new to this, so don't flame me... :wink:
What are the advantages/disadvantages of V6 engines vs Inline-6 engines?
I have read that many prefer the I6 over the V6...
Thanks!! :D
 

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I-6's typically have more torque than V-6....I remember driving my old stick Jeep Wrangler with a straight 6- that thing had some nuts down low......
i've never really been a V-6 fan- alot of the nice car companies, i.e. lexus, BMW, Mercedes use I-6 in their cars...they can get away with only putting out 160 or so HP, because of the torque their motors produce....
 

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dchang98 said:
I am new to this, so don't flame me... :wink:
What are the advantages/disadvantages of V6 engines vs Inline-6 engines?
I have read that many prefer the I6 over the V6...
Thanks!! :D
An I-6 has perfect primary balance and perfectly even power stroke spacing. As a result an I-6 can be among the smoothest running of all engines. In addition, the I-6 has a unique and racy sound you just don't get from a V-6.

Alas, there are several disadvantages that I think will reduce the number of I-6 engines in use in the future.

A high performance straight 6 crank shaft has to have 7 main bearings to control flex and vibration. A V6 only has to have 4 main bearings due to the shorter crank and because opposite connecting rod share a crank journal, riding side by side instead of each con-rod having it's own journal as in an I6. This means that a V6 engine inherently has less internal friction. I think this is one of the reasons that the V6s in Acuras and Infinities get better fuel mileage than the IS.

That long I6 crank can be more than twice as heavy compared to the shorter crank in a V6. Shorter cranks will weigh less even if the same dimensions (other than length) are used, but an additional advantage is that a shorter crank is less prone to distortion/bending/flexing so can be made from smaller dimensions while still providing superior rigidity.

Another very important advantage (from a manufacturer's point of view) is that a V6 is far more compact than an I6. This makes the engine easier to package into a variety of different vehicles. Just look what Nissan has done with their 3.5L V6. They put it in front and rear drive vehicles and just about every model Nissan and Infinty offers some version of it. Great economies of scale there.

Having said all of that, I will lament the passing of one of the few remaining performance I6 engines in existance :( . Nothing else sounds or feels like a nicely tuned I6.
 

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Discussion Starter · #7 ·
wjbertrand said:
dchang98 said:
I am new to this, so don't flame me... :wink:
What are the advantages/disadvantages of V6 engines vs Inline-6 engines?
I have read that many prefer the I6 over the V6...
Thanks!! :D
An I-6 has perfect primary balance and perfectly even power stroke spacing. As a result an I-6 can be among the smoothest running of all engines. In addition, the I-6 has a unique and racy sound you just don't get from a V-6.

Alas, there are several disadvantages that I think will reduce the number of I-6 engines in use in the future.

A high performance straight 6 crank shaft has to have 7 main bearings to control flex and vibration. A V6 only has to have 4 main bearings due to the shorter crank and because opposite connecting rod share a crank journal, riding side by side instead of each con-rod having it's own journal as in an I6. This means that a V6 engine inherently has less internal friction. I think this is one of the reasons that the V6s in Acuras and Infinities get better fuel mileage than the IS.

That long I6 crank can be more than twice as heavy compared to the shorter crank in a V6. Shorter cranks will weigh less even if the same dimensions (other than length) are used, but an additional advantage is that a shorter crank is less prone to distortion/bending/flexing so can be made from smaller dimensions while still providing superior rigidity.

Another very important advantage (from a manufacturer's point of view) is that a V6 is far more compact than an I6. This makes the engine easier to package into a variety of different vehicles. Just look what Nissan has done with their 3.5L V6. They put it in front and rear drive vehicles and just about every model Nissan and Infinty offers some version of it. Great economies of scale there.

Having said all of that, I will lament the passing of one of the few remaining performance I6 engines in existance :( . Nothing else sounds or feels like a nicely tuned I6.
Wow, that's a very detailed explanation !!
Thanks !! :D
 

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dchang98 said:
wjbertrand said:
dchang98 said:
I am new to this, so don't flame me... :wink:
What are the advantages/disadvantages of V6 engines vs Inline-6 engines?
I have read that many prefer the I6 over the V6...
Thanks!! :D
An I-6 has perfect primary balance and perfectly even power stroke spacing. As a result an I-6 can be among the smoothest running of all engines. In addition, the I-6 has a unique and racy sound you just don't get from a V-6.

Alas, there are several disadvantages that I think will reduce the number of I-6 engines in use in the future.

A high performance straight 6 crank shaft has to have 7 main bearings to control flex and vibration. A V6 only has to have 4 main bearings due to the shorter crank and because opposite connecting rod share a crank journal, riding side by side instead of each con-rod having it's own journal as in an I6. This means that a V6 engine inherently has less internal friction. I think this is one of the reasons that the V6s in Acuras and Infinities get better fuel mileage than the IS.

That long I6 crank can be more than twice as heavy compared to the shorter crank in a V6. Shorter cranks will weigh less even if the same dimensions (other than length) are used, but an additional advantage is that a shorter crank is less prone to distortion/bending/flexing so can be made from smaller dimensions while still providing superior rigidity.

Another very important advantage (from a manufacturer's point of view) is that a V6 is far more compact than an I6. This makes the engine easier to package into a variety of different vehicles. Just look what Nissan has done with their 3.5L V6. They put it in front and rear drive vehicles and just about every model Nissan and Infinty offers some version of it. Great economies of scale there.

Having said all of that, I will lament the passing of one of the few remaining performance I6 engines in existance :( . Nothing else sounds or feels like a nicely tuned I6.
Wow, that's a very detailed explanation !!
Thanks !! :D
Thanks and you are welcome. I guess it's just the engineer in me. I just love engines and understanding how they work and why the engineers make some of the decisions they do. All fascinating stuff, at least to a gear head like myself.
 

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How about the cams? aren't there 4 cams in a V6 and only 2 in an inline? Wouldn't it take more of the engine's power to drive those 4 cams instead of 2?
 

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kyo said:
How about the cams? aren't there 4 cams in a V6 and only 2 in an inline? Wouldn't it take more of the engine's power to drive those 4 cams instead of 2?
I had one cam in my V6 GTP.
 

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cb8586 said:
kyo said:
How about the cams? aren't there 4 cams in a V6 and only 2 in an inline? Wouldn't it take more of the engine's power to drive those 4 cams instead of 2?
I had one cam in my V6 GTP.
I'm not too sure about this, but I believe you had 2 cams even though your engine is a SOHC (single overhead cam) because of the v6 configuration you would need a cam for each 3 cylinders, therefore you had two cams.
 

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The first car I ever owned was a straight 6 flathead '51 Plymouth that I got in 1958. I've had all sorts of other cars in the meantime, and now I'm back to the straight six again in the IS300. :)

Some of old sixes would run pretty good. I remember a friend who had a '51 Ford six cylinder with the three speed column shif that would do 90 MPH in second gear. :lol:

I think the V-6 only came into its own due to the ability to stuff it crossways in the FWD weight and gas saving cars. Otherwise, I don't think there was really a that much need for it. IMHO
 

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I don't think the IS300's problem is the inline 6 at all, the car just needs to drop a couple hundred pounds and it would perform the nuts. Maybe an engine update would help too. I'd rather have a 215 hp inline than a 240 hp V6 any day, cause of the sound. Taking out some sound deadening would let you hear that sweet sound better, and would make the car lighter. I wish Toyota would make a lighter, louder, low frills IS.
 

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kyo said:
How about the cams? aren't there 4 cams in a V6 and only 2 in an inline? Wouldn't it take more of the engine's power to drive those 4 cams instead of 2?
It depends on the engine design, some push rod V6s have only a single cam. All things being equal though, yes, A DOHC V6 will have 4 cams and an I6 will have only 2. Most of the friction in the valve train happens at the cam lobes though, and in this regard the numbers will be equal, assuming both engines have the same number of valves per cylinder. Also remember that the cams only rotate at 1/2 the crankshaft speed and carry much smaller loads. The camshaft's contribution to internal friction is much less significant than the crankshaft.

In my first reply I forgot to mention that the key advantage of the shorter, lighter crankshaft is lower weight. Similarly, the shorter more rigid engine block can be built lighter for a V6 compared to an I6. Someone mentioned that the IS needs to be lighter to improve it's performance and fuel efficiency. I agree. That I6, with it's long crank and heavy iron block is low hanging fruit for an engineer looking to reduce overall weight. The 3.3 L V6 used in the ES330 and RX330 and a version of which is likely slated for use in the next generation IS has an aluminum block and is probably a couple hundred pounds lighter that the hell-built-for-stout I6 currently used.

Another potential handling advantage is that the shorter, more compact V6 can have it's center of mass located farther back in the engine bay. That'll take some weight off the front end and improve the overall weight distribution of the car. This is exactly what Infinity has done with the V6 in the G35 to great success.

One of the biggest casulties of changing over to the V6 however will be the loss of tuner parts. If they bother, it'll take the aftermarket a few years at best to tool up significant hop up stuff for the new engine. If you are heavily into mods, get your I6 equipped IS while the getting is good!
 

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wjbertrand said:
kyo said:
One of the biggest casulties of changing over to the V6 however will be the loss of tuner parts. If they bother, it'll take the aftermarket a few years at best to tool up significant hop up stuff for the new engine. If you are heavily into mods, get your I6 equipped IS while the getting is good!
That is unfortunate because the IS caters to a small target audience targeted at performance. Assumming the IS gets the V6, then about 20 to 30 thousand people a year get an IS (if that even). This is too small a market for many of the tuners (except TRD) to really go after. All new R&D will be done and it will probably take forever. Even Nissan's V6 took awhile to get parts and they use their v6 in ALL of their lineups. Between the Z, G35, and Maxima/Altima, they must sell 2 to 3 hundred thousand cars with the v6.
 

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dchang98 said:
I am new to this, so don't flame me... :wink:
What are the advantages/disadvantages of V6 engines vs Inline-6 engines?
I have read that many prefer the I6 over the V6...
Thanks!! :D
power is determined really by displacement. as long as their the same displacement then they'll produce the same amount of power (non-fi that is).

difference is overall dimensions. v6 is more compact and allows for more interior room. since americans are big and want more interior room, companies usually put in a V6 to maximize interior space.
 

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wjbertrand said:
This means that a V6 engine inherently has less internal friction. I think this is one of the reasons that the V6s in Acuras and Infinities get better fuel mileage than the IS.
excellent explanation, but what about the 330i having outstanding fuel mileage? i think the IS engine is just old...
 

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Cleo said:
wjbertrand said:
This means that a V6 engine inherently has less internal friction. I think this is one of the reasons that the V6s in Acuras and Infinities get better fuel mileage than the IS.
excellent explanation, but what about the 330i having outstanding fuel mileage? i think the IS engine is just old...
yah, the is300 engines is one of the oldest engines. also one of the most inefficient engines.
 

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Here is something to add to the question...

Why does it seem the I6 is a better platform to boost? Is it the near perfect balance of the motor that allows this? Just curious..anyone?
 

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One reason is because with a straight-six, all your exhaust outlets are on one side of the engine, which makes it easier to do the plumbing for a single turbo set up.

Specifically with the IS, since it uses the 2jz, it is a good platform for boost because the enging is strong as hell, which allows it to have higher boost than an average aluminum block for example.

To me it seems like the I6 is a dying breed. More and more car manufacturers are turning to aluminum block V6s and are able to get more power, gas milage and less weight.

It would be nice though, to see Toyota develop a new I6 that can compete. Maybe a 3jz 8) Or at least they could retune the current design to improve efficiency and power output. Maybe improve the VVT-I or have VVTL-I option. The might cause havoc in the FI crowd though.
 
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