A guide to the "V6 vs V8" debate
I’ve been doing a lot of searching, and it comes up a bunch so I figured maybe a single thread to have as much information as possible would be helpful. If it’s good enough maybe put it as a sticky so people don’t keep asking. If not a sticky hopefully at least a good thread for reference.
I’d like to start by saying these are not my opinion, it is just information I’ve gathered access multiple threads. Please give any and all constructive feedback, if anything is wrong please let me know and if I should add anything please let me know.
We should start by noting both are incredibly reliable and can go 500,000+ miles as long as you take care of them with regular service. Neither motor is more reliable than the other, although in my research one does has more maintenance than the other but more on that later.
Also I’m a little bias in gathering my information so everything is regarding the 4x4/AWD models. Some of the following information does not apply to RWD models. Also I’ve tried to leave opinion out as much as possible. So the “sound of the V8” is not a point (even if it is true). Please know that everything should be used a reference and not as "the golden rule".
Here we go basic comparison of side by side comparison.
Horsepower numbers have changed between the years (outside of VVT-I change for the 2005+ V8s, the HP/TQ changes are more from SAE changes across all car brands. Again please use the HP numbers as a reference and not the golden rule.
Notes on the V6:
The 1GR-FE motor was a newly (at the time) designed motor. By comparison the V8 was used in the land cruiser for years.
Headgasket
The early motors seem to have head gasket failures. It seems more that 2005 and on the problem seems to have pretty much gone away. Even with the earlier year 4th gens, the head gasket problem wasn’t nearly as bad as the previous gen motors.
Noise
The V6 is has been mention by the majority of owners as a noisy motor, especially when compared to the V8. The noise is the "ticking/tacking" nature of the V6,
Another item of note: the 1GRFE can not be bored over due to the design (or material, can't remember) of the cylinder walls.
++ TC problems See blow as both motors share the problem
Misc
It's well known that the V6 has plenty of power for the truck. The motor is used across the Toyota line up including but not limited to the Tacoma and the 5th gen 4Runner. You would really only notice the lack of power when carrying a lot of weight and/or during long freeway inclines (the transmission has to downshift to maintain speed).
Notes on the V8:
The 4th gen to date has been (and most likely) the only 4Runner to be given a V8 option.
Belt driven, needs to be changed every (approx.) 100k, Approx $500 for just belt or $1050 for full water pump pulleys tensioners etc. (parts are start at $180 and go up depending on type of kit and how many pieces)
Exhaust Manifold
They are known for a “ticking” sound. The sound is from an exhaust manifold cracking and leaking that makes the sound. OEM replacement is aprox $1,200 in parts alone. Doug Thorley make a set of aftermarket headers for approx. $710-782, they do require a weld on cat or straight pipe, which does add more to the cost. Some are quote as much as 10-12 hours from local weld shops. It should be noted the crack isn’t enough of a problem to throw a CEL nor cause any real damage so most people consider it more of a nuisance more of an annoyance (sound) rather than a problem. It should also be noted it’s not the only ticking sound fuel line pulsing can cause ticking as well.
Good link for more information regarding the exhaust “tick”.
http://www.toyota-4runner.org/4th-gen-t4rs/115116-v8-aftermarket-exhaust-manifold.html
Secondary Air Injection Pump (SAIP) failure (a VVT-I V8 problem only, pre 05 V8's do not have this issue)
There is “simple” bypass which fixes this issue. It’s a bypass as well as an exhaust blocking plate. Hewitt technologies and user Slyfox75 seem to be two different ways to do it. I can’t speak to Slyfox but HT’s kit have a plug and play option which many like. Most people say it’s better to do the bypass than to wait for the problem. Once the SAIP air valves are open they may get stuck open and the V8 goes into 'limp mode' and there will be CEL's. At that point it is an expensive fix, best practice is preventive maintenance before the dreaded 'limp mode'
When this happens, it’s best described as a shop vacuum like sound. It seems noted to be about a 10-30 minute job that looks worse than it is, and actually easy once you “dive in”.
Really good link regarding this problem is below, although there are TON of good comments post #194 was one I personally have saved so I figured noting it here would be nice as well.
http://www.toyota-4runner.org/4th-g...air-injection-pump-failure-v8s-important.html
++ TC problems See blow as both motors share the problem
Misc
The V8s does have a transmission cooler, given that towing and even day to day use the V8 should get more life and it should be easier on the transmission when compared to V6.
General Info - most of this in connected with each other so not as easy to split it per motor
++ TC problems
Both motors having problems with the TC. The TC cases seems to have two different problems, either the 4x4 gets stuck and is unable to function or the seals leak in the TC.
The issue is mostly agreed upon by everyone due to a lack of proper ownership practices, i.e. the previous or current owner is not exercising the 4WD system reguarly as indicated in their owners manual. Such an act would prevent the actuators from sticking (another common issue) and the seals from drying out as well as making sure the 4WD system functions properly.
In other words, the issue is because people don't read the owner's manual and/or do not properly maintain their vehicle by once a month exercising the 4WD system in Hi, Lo, and CDL positions for a short distance (100~300ft) to properly lubricate the transfer case and its components.
Side note: Cost to replace TC range from $1200-$2000 if warranty is out.
This is not limited to 4Runners, it also affects the Tacoma and FJ Cruisers as they use similar style transfer case actuators.
Boost
Although my first research showed that the V6 handled boost better than the V8. It's not that easy of a black and white answer. Lets start with the first rumor which was the V8 failed under boost due to weak connecting rods, that failed under boost. Parts of the information was true. Different V8's had different conrods however all of them are forged. Although forged not all are quite beefy enough for boosted applications.
Here is a link to lextreme.com with a side-by-side picture of the various versions of the Toyota "UZ" family of V8's from 1989 to 2006.
http://www.lextreme.com/forums/inde...ecting-rods-forged-or-cast.14121/#post-119553
URD (Underdog Racing Development) as of 2017 still produces a supercharger kit for the 2UZ-FE, but most users with experience will recommend the connecting rods be replaced with thicker 1UZ-FE connecting rods or aftermarket connecting rods like from lextreme.com. Here's a link to a discussion about "cast vs forged" in Japan-produced vs US produced where it's confirmed all Toyota connecting rods are sintered and forged. http://www.lextreme.com/forums/index...1/#post-119553
There more and better information about this within the first 3 pages of this thread should you want to learn more.
Misc
The front differential although is different. The owners manual states the V6 front diff is 1.6q, the V8 is 1.5q. It doesn't seem anyone has an answer, but really doesn't matter, Toyota did it.
It was originally mentioned the service intervals might be different however it has been corrected. The maintenance interval is no different in the owners manual. Both engines always have the axle shafts engaged and turning so there are gears turning and heat buildup with either engine. When you select 4WD in a V6 all that happens is the front drive shaft is engaged by the transfer case, the axle shafts are already turning.
So in short "TL : DR":
Both are outstanding motors/options for an outstanding our trucks. Many people believe the very little mpg that you give up is worth the V8’s tq and unique quality. That said for the majority of the people the V6 provides enough power and tq for 90% of your needs. This is showcased in the fact that they took away the V8 option, and use the same V6 for the 5th gen (also used the Tacoma and many others).
The V8 does have its unique challenges as well and I tried best to note that. During my research most the threads did not address these and I feel like for many people it’s a part of the choice. From what I can get although both motors can hit 500k the V8 might need a little more love along the way. Although most if address earlier enough tend to not be major problems.
Also it seems that if you have a lot of towing and more moving lots of weight the V8 seems to be the better choice. That’s when the weakness and/or strength of each motor shines the most.
Again anyone who would like please give more feedback. Also I wrote this, with only 2 hours of sleep so excuse the the grammar I'll clean it up through out the day.
I’ve been doing a lot of searching, and it comes up a bunch so I figured maybe a single thread to have as much information as possible would be helpful. If it’s good enough maybe put it as a sticky so people don’t keep asking. If not a sticky hopefully at least a good thread for reference.
I’d like to start by saying these are not my opinion, it is just information I’ve gathered access multiple threads. Please give any and all constructive feedback, if anything is wrong please let me know and if I should add anything please let me know.
We should start by noting both are incredibly reliable and can go 500,000+ miles as long as you take care of them with regular service. Neither motor is more reliable than the other, although in my research one does has more maintenance than the other but more on that later.
Also I’m a little bias in gathering my information so everything is regarding the 4x4/AWD models. Some of the following information does not apply to RWD models. Also I’ve tried to leave opinion out as much as possible. So the “sound of the V8” is not a point (even if it is true). Please know that everything should be used a reference and not as "the golden rule".
Here we go basic comparison of side by side comparison.
Horsepower numbers have changed between the years (outside of VVT-I change for the 2005+ V8s, the HP/TQ changes are more from SAE changes across all car brands. Again please use the HP numbers as a reference and not the golden rule.
Notes on the V6:
The 1GR-FE motor was a newly (at the time) designed motor. By comparison the V8 was used in the land cruiser for years.
Headgasket
The early motors seem to have head gasket failures. It seems more that 2005 and on the problem seems to have pretty much gone away. Even with the earlier year 4th gens, the head gasket problem wasn’t nearly as bad as the previous gen motors.
Noise
The V6 is has been mention by the majority of owners as a noisy motor, especially when compared to the V8. The noise is the "ticking/tacking" nature of the V6,
Another item of note: the 1GRFE can not be bored over due to the design (or material, can't remember) of the cylinder walls.
++ TC problems See blow as both motors share the problem
Misc
It's well known that the V6 has plenty of power for the truck. The motor is used across the Toyota line up including but not limited to the Tacoma and the 5th gen 4Runner. You would really only notice the lack of power when carrying a lot of weight and/or during long freeway inclines (the transmission has to downshift to maintain speed).
Notes on the V8:
The 4th gen to date has been (and most likely) the only 4Runner to be given a V8 option.
Belt driven, needs to be changed every (approx.) 100k, Approx $500 for just belt or $1050 for full water pump pulleys tensioners etc. (parts are start at $180 and go up depending on type of kit and how many pieces)
Exhaust Manifold
They are known for a “ticking” sound. The sound is from an exhaust manifold cracking and leaking that makes the sound. OEM replacement is aprox $1,200 in parts alone. Doug Thorley make a set of aftermarket headers for approx. $710-782, they do require a weld on cat or straight pipe, which does add more to the cost. Some are quote as much as 10-12 hours from local weld shops. It should be noted the crack isn’t enough of a problem to throw a CEL nor cause any real damage so most people consider it more of a nuisance more of an annoyance (sound) rather than a problem. It should also be noted it’s not the only ticking sound fuel line pulsing can cause ticking as well.
Good link for more information regarding the exhaust “tick”.
http://www.toyota-4runner.org/4th-gen-t4rs/115116-v8-aftermarket-exhaust-manifold.html
Secondary Air Injection Pump (SAIP) failure (a VVT-I V8 problem only, pre 05 V8's do not have this issue)
There is “simple” bypass which fixes this issue. It’s a bypass as well as an exhaust blocking plate. Hewitt technologies and user Slyfox75 seem to be two different ways to do it. I can’t speak to Slyfox but HT’s kit have a plug and play option which many like. Most people say it’s better to do the bypass than to wait for the problem. Once the SAIP air valves are open they may get stuck open and the V8 goes into 'limp mode' and there will be CEL's. At that point it is an expensive fix, best practice is preventive maintenance before the dreaded 'limp mode'
When this happens, it’s best described as a shop vacuum like sound. It seems noted to be about a 10-30 minute job that looks worse than it is, and actually easy once you “dive in”.
Really good link regarding this problem is below, although there are TON of good comments post #194 was one I personally have saved so I figured noting it here would be nice as well.
http://www.toyota-4runner.org/4th-g...air-injection-pump-failure-v8s-important.html
++ TC problems See blow as both motors share the problem
Misc
The V8s does have a transmission cooler, given that towing and even day to day use the V8 should get more life and it should be easier on the transmission when compared to V6.
General Info - most of this in connected with each other so not as easy to split it per motor
++ TC problems
Both motors having problems with the TC. The TC cases seems to have two different problems, either the 4x4 gets stuck and is unable to function or the seals leak in the TC.
The issue is mostly agreed upon by everyone due to a lack of proper ownership practices, i.e. the previous or current owner is not exercising the 4WD system reguarly as indicated in their owners manual. Such an act would prevent the actuators from sticking (another common issue) and the seals from drying out as well as making sure the 4WD system functions properly.
In other words, the issue is because people don't read the owner's manual and/or do not properly maintain their vehicle by once a month exercising the 4WD system in Hi, Lo, and CDL positions for a short distance (100~300ft) to properly lubricate the transfer case and its components.
Side note: Cost to replace TC range from $1200-$2000 if warranty is out.
This is not limited to 4Runners, it also affects the Tacoma and FJ Cruisers as they use similar style transfer case actuators.
Boost
Although my first research showed that the V6 handled boost better than the V8. It's not that easy of a black and white answer. Lets start with the first rumor which was the V8 failed under boost due to weak connecting rods, that failed under boost. Parts of the information was true. Different V8's had different conrods however all of them are forged. Although forged not all are quite beefy enough for boosted applications.
Here is a link to lextreme.com with a side-by-side picture of the various versions of the Toyota "UZ" family of V8's from 1989 to 2006.
http://www.lextreme.com/forums/inde...ecting-rods-forged-or-cast.14121/#post-119553
URD (Underdog Racing Development) as of 2017 still produces a supercharger kit for the 2UZ-FE, but most users with experience will recommend the connecting rods be replaced with thicker 1UZ-FE connecting rods or aftermarket connecting rods like from lextreme.com. Here's a link to a discussion about "cast vs forged" in Japan-produced vs US produced where it's confirmed all Toyota connecting rods are sintered and forged. http://www.lextreme.com/forums/index...1/#post-119553
There more and better information about this within the first 3 pages of this thread should you want to learn more.
Misc
The front differential although is different. The owners manual states the V6 front diff is 1.6q, the V8 is 1.5q. It doesn't seem anyone has an answer, but really doesn't matter, Toyota did it.
It was originally mentioned the service intervals might be different however it has been corrected. The maintenance interval is no different in the owners manual. Both engines always have the axle shafts engaged and turning so there are gears turning and heat buildup with either engine. When you select 4WD in a V6 all that happens is the front drive shaft is engaged by the transfer case, the axle shafts are already turning.
So in short "TL : DR":
Both are outstanding motors/options for an outstanding our trucks. Many people believe the very little mpg that you give up is worth the V8’s tq and unique quality. That said for the majority of the people the V6 provides enough power and tq for 90% of your needs. This is showcased in the fact that they took away the V8 option, and use the same V6 for the 5th gen (also used the Tacoma and many others).
The V8 does have its unique challenges as well and I tried best to note that. During my research most the threads did not address these and I feel like for many people it’s a part of the choice. From what I can get although both motors can hit 500k the V8 might need a little more love along the way. Although most if address earlier enough tend to not be major problems.
Also it seems that if you have a lot of towing and more moving lots of weight the V8 seems to be the better choice. That’s when the weakness and/or strength of each motor shines the most.
Again anyone who would like please give more feedback. Also I wrote this, with only 2 hours of sleep so excuse the the grammar I'll clean it up through out the day.
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