Why no more inline 6
01-11-07, 04:01 PM
#16
i guess this is true.
also i don't mean put inline 6's in everything, just keep things the way they've always been (gs, is, supra) the new sc430 to me went a completely different direction than the sc300 so leave it out, or just use it in the supra to keep it exclusive.
a unique thought would be to just change the name of the toyota supra to lexus ??????, maybe that was the thought behind the lfa.
someone told me that the g35 is the new nissan skyline.
i love the I6, kinda like those V8 guys who think if it does'nt have a V8 under the hood it's a rice rocket.
also how can they make a v6,v8,v10 or v12 supra? most people want to stroke there 2jz's to 3.2 or 3.4 so the love for the engine is still there, and anyone i meet that owns a supra wants the same thing more power more torque but they will never put a v8 or v12 under the hood of a supra, even if they can make more power by junking the 2jz.
also if a used 94TT supra goes for $20.000+, by a strech of the imagination a 2008 4.0L I6 TT 450hp(LEXUS)supra will definatly sell for $40000-$50.000+,
also i don't mean put inline 6's in everything, just keep things the way they've always been (gs, is, supra) the new sc430 to me went a completely different direction than the sc300 so leave it out, or just use it in the supra to keep it exclusive.
a unique thought would be to just change the name of the toyota supra to lexus ??????, maybe that was the thought behind the lfa.
someone told me that the g35 is the new nissan skyline.
i love the I6, kinda like those V8 guys who think if it does'nt have a V8 under the hood it's a rice rocket.
also how can they make a v6,v8,v10 or v12 supra? most people want to stroke there 2jz's to 3.2 or 3.4 so the love for the engine is still there, and anyone i meet that owns a supra wants the same thing more power more torque but they will never put a v8 or v12 under the hood of a supra, even if they can make more power by junking the 2jz.
also if a used 94TT supra goes for $20.000+, by a strech of the imagination a 2008 4.0L I6 TT 450hp(LEXUS)supra will definatly sell for $40000-$50.000+,
And a V10 two seat coupe with carbon fiber parts all over the place priced at ~120k is not a proper Supra replacement. I could definitely see the Supra coming back as a N/A 3.5 V6 with maybe a V8 variant or V6TT. The only problem they'll have at this point is car overlap (IS coupe). Why buy a IS coupe when you can buy a Supra cheaper?
01-11-07, 05:18 PM
#17
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lobuxracer...
good explanation, what do you mean by service life?
in actuallity there are pros and cons to each?
so given the choice you would much rather have a TTv6 over a TTI6 ?
arn't V blocks prone to cracking when under too much stress?
and also please explain nickle content, is the 2j the only engine with high nickle.
good explanation, what do you mean by service life?
in actuallity there are pros and cons to each?
so given the choice you would much rather have a TTv6 over a TTI6 ?
arn't V blocks prone to cracking when under too much stress?
and also please explain nickle content, is the 2j the only engine with high nickle.
01-11-07, 05:35 PM
#18
Nice explanation. 
The 7M, didn't they under torque the head like 20 ftlbs? Those Supras and Cressidas died a fast death once they came to about 80-100K miles.
I wanted the 2-GS with the 2JZ at the time. Having driven the 5M for 180K I grew to really like the I-6.
The 7M, didn't they under torque the head like 20 ftlbs? Those Supras and Cressidas died a fast death once they came to about 80-100K miles.
I wanted the 2-GS with the 2JZ at the time. Having driven the 5M for 180K I grew to really like the I-6.
01-11-07, 05:59 PM
#19
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Supras were traditionally inline 6 cars. The 2JZ block is actually a forklift block, so Toyota had considerable practical experience with its strength and durability long before it was installed in a Supra. It's also a high nickel content cast iron, so it's extremely strong (essential because of the length problem) and fortunately for the boost heads, it will tolerate really insane boost levels (closed deck, high nickel cast iron). It is not a light engine though. IMHO, durability under pressure is one of the biggest reasons they chose it for the MkIV Supra.
V configurations require a specific angle between the banks (6's like 60 degrees, 8's like 90), or they need offset individual rod journals on the crank to achieve satisfactory primary balance. Inline engines don't have this issue because the vibration is fundamentally in a single plane. V engines need more complex main journals for this same reason - the forces on the crank are coming from two planes, so vibration will try to push the crank out of the block in two different directions requiring a more stable main bearing support from the block. The V-6 crank is still simpler and cheaper to manufacture.
Inline engines like 6's are also more prone to headgasket failure. The 7MG is a perfect example of this. A V engine's heads are much shorter and can be machined to fit more easily (read cheaper) than a single longer piece. Casting a single longer piece without core shift or other casting faults is harder (read more expensive), and this is true for both block and head.
While it is true, the parts count for a DOHC inline 6 is smaller than the parts count for a DOHC V-6, the other production efficiencies, and the simplicity of grinding a cam half the length of the I-6 cam make it not such a big deal. From a pure friction perspective, it's pretty close to a wash, and again, in the valve train those long cams are more prone to torsional problems (and subsequent valve timing errors) than the shorter cams found in the V-6.
Basic considerations - bore and stroke - are limited on the I-6 for packaging reasons. Bigger bore means longer engine and all the negatives (especially NVH) associated with more length. Longer stroke means taller, so the hood line suffers. With the V-6, you can easily go oversquare (bore greater than stroke) without having to add inches to accomodate the length increase or go undersquare without having to raise the hoodline to accommodate the additional height. With the I-6, these are 1:1 relationships, V-6 <1:1, so packaging wins again.
So, tradition was a big player in why the Supra got the 2JZ. NVH, emissions, specific output, and more than anything, packaging; are why we are seeing mostly V-6s today.
Oh, yeah, there's no way the engine configuration is going to determine how much power can be made. It might affect service life, but 6 cylinders with 3 litres turbocharged is going to make the same power regardless of configuration assuming all other parameters are equal.
V configurations require a specific angle between the banks (6's like 60 degrees, 8's like 90), or they need offset individual rod journals on the crank to achieve satisfactory primary balance. Inline engines don't have this issue because the vibration is fundamentally in a single plane. V engines need more complex main journals for this same reason - the forces on the crank are coming from two planes, so vibration will try to push the crank out of the block in two different directions requiring a more stable main bearing support from the block. The V-6 crank is still simpler and cheaper to manufacture.
Inline engines like 6's are also more prone to headgasket failure. The 7MG is a perfect example of this. A V engine's heads are much shorter and can be machined to fit more easily (read cheaper) than a single longer piece. Casting a single longer piece without core shift or other casting faults is harder (read more expensive), and this is true for both block and head.
While it is true, the parts count for a DOHC inline 6 is smaller than the parts count for a DOHC V-6, the other production efficiencies, and the simplicity of grinding a cam half the length of the I-6 cam make it not such a big deal. From a pure friction perspective, it's pretty close to a wash, and again, in the valve train those long cams are more prone to torsional problems (and subsequent valve timing errors) than the shorter cams found in the V-6.
Basic considerations - bore and stroke - are limited on the I-6 for packaging reasons. Bigger bore means longer engine and all the negatives (especially NVH) associated with more length. Longer stroke means taller, so the hood line suffers. With the V-6, you can easily go oversquare (bore greater than stroke) without having to add inches to accomodate the length increase or go undersquare without having to raise the hoodline to accommodate the additional height. With the I-6, these are 1:1 relationships, V-6 <1:1, so packaging wins again.
So, tradition was a big player in why the Supra got the 2JZ. NVH, emissions, specific output, and more than anything, packaging; are why we are seeing mostly V-6s today.
Oh, yeah, there's no way the engine configuration is going to determine how much power can be made. It might affect service life, but 6 cylinders with 3 litres turbocharged is going to make the same power regardless of configuration assuming all other parameters are equal.
01-11-07, 07:54 PM
#20
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sc3boost - I think your sig explains why no more Toyota/Lexus I-6. 
Things change.
Things change.
01-11-07, 10:44 PM
#22
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Another thing, if they were to produce such cars they would probably have to mate them to RWD drivetrains as placing an I6 longitudinally would make a car one bloated beast. The reason Lexus can make their cars inexpensive is because they share parts and platforms with Toyotas. What RWD Toyota sedan/coupe would sell with a higher price tag? That's a reason why the Supra died, they couldn't reduce costs enough to make them sell.
It works for BMW because they don't make economic vehicles.
It works for BMW because they don't make economic vehicles.
01-12-07, 12:43 AM
#23
Out of Warranty
Chrysler Corporation's old Slant-6 largely overcame at least the vertical component of the packaging problem by laying the cylinders 30 degrees to starboard, placing the intake plumbing on top and relegating the exhaust header to the underside of the block. To reduce overall length, the water pump was moved from the face of the block to a position alongside.
The factory offered a "Hyper-Pac" consisting of manifolds, and a Carter AFB 4-bbl and a cam that turned a rather sedate Valiant into a monster. Offenhauser and other manufacturers improved on these manifolds and heads to create some impressive "economy" cars. They took the first eight places at Daytona in 1960 - in a short-lived "compact car" division of NASCAR.
These engines were extremely rugged and loved by a band of enthusiasts who regularly bored them out to nearly 4 liters, added more sophisticated manifolds, and headers to extract crazy amounts of power from the engine. Designed to redline at about 4500 rpm with only 4 main bearings, despite their hefty size, this power plant (with extensive modification) was regularly taken to 9000 rpm by a community of 6-cyl dragsters who must have written the book on physical bravery.
This engine, designed for service in everything from compacts to full-sized pickups was torquey, incredibly smooth, and about as reliable as man-made devices get. It served Chrysler essentially unchanged from 1960 into the 21st Century in applications all over the world. Vestiges of its lay-down technology can be seen in the Honda S2000 and BMW M6 engines today.
The factory offered a "Hyper-Pac" consisting of manifolds, and a Carter AFB 4-bbl and a cam that turned a rather sedate Valiant into a monster. Offenhauser and other manufacturers improved on these manifolds and heads to create some impressive "economy" cars. They took the first eight places at Daytona in 1960 - in a short-lived "compact car" division of NASCAR.
These engines were extremely rugged and loved by a band of enthusiasts who regularly bored them out to nearly 4 liters, added more sophisticated manifolds, and headers to extract crazy amounts of power from the engine. Designed to redline at about 4500 rpm with only 4 main bearings, despite their hefty size, this power plant (with extensive modification) was regularly taken to 9000 rpm by a community of 6-cyl dragsters who must have written the book on physical bravery.
This engine, designed for service in everything from compacts to full-sized pickups was torquey, incredibly smooth, and about as reliable as man-made devices get. It served Chrysler essentially unchanged from 1960 into the 21st Century in applications all over the world. Vestiges of its lay-down technology can be seen in the Honda S2000 and BMW M6 engines today.
01-12-07, 02:24 AM
#24
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lobuxracer...
good explanation, what do you mean by service life?
in actuallity there are pros and cons to each?
so given the choice you would much rather have a TTv6 over a TTI6 ?
arn't V blocks prone to cracking when under too much stress?
and also please explain nickle content, is the 2j the only engine with high nickle.
good explanation, what do you mean by service life?
in actuallity there are pros and cons to each?
so given the choice you would much rather have a TTv6 over a TTI6 ?
arn't V blocks prone to cracking when under too much stress?
and also please explain nickle content, is the 2j the only engine with high nickle.
Yes, there are pros and cons to each configuration. Neither is inherently superior, and neither is inherently inferior. They are both completely dependent upon how the engineer executed the design.
Given a choice as an engine developer, I'd rather have the inline 6. I have a lot more freedom to experiment with intake and exhaust configurations with the inline solution. As an example, a friend of mine wanted a 2JZ-GE head ported to deliver under boost, mostly because I believe the exhaust ports on the GE head are far superior to the GTE head. I ported it to resemble a GTE head by raising the roof, widening the opening, blending it all together, and leaving the floor intact on the intake side, while just doing a clean up on the exhausts (because he didn't want me to weld up the exhaust floor like I wanted to.) This is pretty simple and straightforward on the inline engine. On the V engine, I'd have to come up with complex manifolding to support the effectively steeper intakes, and I might not be able to do this without a LOT of development work. So, given the choice, I'll take the inline for simplicity.
Yes, V blocks are more prone to cracking under stress because they're being abused in two planes simultaneously vs. one plane for inline engines. It just means you need to do FEA on the V block and figure out where you need to be fat and where you can afford to be thin. The biggest concern I have with most new engine designs is the apparent ubiquity of open decks. My chief complaint with open decks is they are weak exactly where I want them to be strongest. So the likelihood I'll be able to feed an open deck block 45 psig boost is pretty small, especially with the current trend toward aluminium blocks with cast in iron liners. But I digress...
The 2JZ blocks are not unique in their nickel content, it's just that Toyota really got it right for the boost junkies with this choice. A closed deck and high nickel content cast iron mean the block will tolerate insane boost levels (I've heard of guys running 55+ psi boost on gasoline - not pump gas mind you, but still, pretty impressive for a gasoline engine.) The whole point of high nickel content is it makes for a much stronger block in terms of thermal shock. Link to technical article on cast iron alloys.
01-12-07, 02:28 AM
#25
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The biggest point of grief with the 7MG was the metal/paper composite head gasket. All the 2JZs have a multi-sheet stainless steel gasket with a special fluoropolymer coating that allows the aluminium head to expand and contract at different rates than the cast iron block without shredding the gasket. Toyota were so proud of this they specifically mentioned it in the MkIV Supra New Car Features manual.
01-12-07, 05:48 AM
#28
Lexus Fanatic
The 170 and 225 c.i. slant-six engines, by the standards of the day, were indeed the very definition of toughness and durability ( I know...I drove them many miles myself, all over the Eastern U.S. ). But they were anything BUT smooth and quiet. There was a small but distinct vibration a idle, the solid lifters ticked constantly, and at higher RPM's, the engine felt and sounded like it was going to come apart...though it rarely did. This, in addition to the rather noisy 3-speed TorqueFlite automatic, and the front torsion bar / rear leaf spring suspension that transmitted road noise and vibration like a telephone line, made Valiants, Darts, and other slant-six Chrysler products less smooth and quiet than their Ford and GM competiton...the noisy, clattery, air-cooled, rear-engine Chevy Corvair being the main exception.
01-12-07, 06:07 AM
#29
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Given a choice as an engine developer, I'd rather have the inline 6. I have a lot more freedom to experiment with intake and exhaust configurations with the inline solution.
As an example, a friend of mine wanted a 2JZ-GE head ported to deliver under boost, mostly because I believe the exhaust ports on the GE head are far superior to the GTE head. I ported it to resemble a GTE head by raising the roof, widening the opening, blending it all together, and leaving the floor intact on the intake side, while just doing a clean up on the exhausts (because he didn't want me to weld up the exhaust floor like I wanted to.) This is pretty simple and straightforward on the inline engine.
On the V engine, I'd have to come up with complex manifolding to support the effectively steeper intakes, and I might not be able to do this without a LOT of development work. So, given the choice, I'll take the inline for simplicity.
As an example, a friend of mine wanted a 2JZ-GE head ported to deliver under boost, mostly because I believe the exhaust ports on the GE head are far superior to the GTE head. I ported it to resemble a GTE head by raising the roof, widening the opening, blending it all together, and leaving the floor intact on the intake side, while just doing a clean up on the exhausts (because he didn't want me to weld up the exhaust floor like I wanted to.) This is pretty simple and straightforward on the inline engine.
On the V engine, I'd have to come up with complex manifolding to support the effectively steeper intakes, and I might not be able to do this without a LOT of development work. So, given the choice, I'll take the inline for simplicity.
What is "underboost" and what was the ultimate purpose of underboosting--to fit a turbo?
Last edited by natnut; 01-12-07 at 06:10 AM.
01-12-07, 09:25 AM
#30
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that ge and gte head thing is still wierd to me though...
so the block is the crowning jewel of our 2j's, i personally would rather mod a I6 over a v6.
so because of the construction of the 2jz's they will easily out perform other inline 6's from other manufactures?
what about the TVR 4.0L I6
so the block is the crowning jewel of our 2j's, i personally would rather mod a I6 over a v6.
so because of the construction of the 2jz's they will easily out perform other inline 6's from other manufactures?
what about the TVR 4.0L I6