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Toyota UR Series Engines


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Four things will always be certain - War, Love, Taxes and popular cars once old donate their engines to hot rodders.



That being said the newer Lexus cars seem to be selling as good as ever around the metropolitan areas like SF. This leads me to conclude that in due time we'll see them drop to just as unbelievably low prices as the current cream of the crop of amazing donors.


You can get a whole 1UZFE donor car for well under $3,000, in decent shape, and drive it home! And the infinity VH45DE is in the same boat as well, making it prime swap material.



I want this thread to be a source of information dedicated to what we know about the next generation of these rolling organ donors.



What we've found from the current UZ


- No out of the box tranny options. All came as autos and they all stunk.

- Most fitment issues are related to the oil pan, and exhaust clearing the steering

- Aftermarket is slightly there, but expensive. Consider yourself largely on your own



What I've found about the newer UR engines


- All seem to be a true rear sump (yay!)

- Thus far I've only seen auto versions (even in the IS F)

- Looks like they're being made in more numbers, though more varieties than the old UZ engines



Into the meat:


The old UZ was offered in three variations. 1UZ, 2UZ, and 3UZ, in 4.0, 4..7, and 4.3 liter displacements respectively. This engine went through many iterations with very little information offered from toyota about it all. For example, the rods changed often through the history of the 1UZFE.


The new UZ is currently offered in three variations as well. 1UR, 2UR and 3UR in 4.6, 5.0 and 5.7 liter displacements respectively.


A lot of the displacement increase on the lower displacement variations was from bore size, not just stroke.The new king of the range is a whole liter larger, and gains this through stroke alone compared to the old 4.7 liter 2UZ. These following spec listings are listed by displacement step, not number of engine code.


Old 1UZ was 87.5 x 82.5 (mm) while the new 1UR is 94 x 83 (mm).


Old 3UZ was 91 x 82.5 (mm) while the new 2UR is 94 x 89.5 (mm).


Old 2UZ was 94 x 84 (mm) while the new 3UR is 94 x 102 (mm).


Note the huge stroke increase on the new engines as displacement ramps up. Like the older engines these new ones probably all have their own blocks that aren't necessarily easily interchanged.



I haven't see enough evidence yet, but it looks like the new 1UR is very compact like the 1UZ. Seems as though toyota is still just as dedicated to keeping the head narrow.


For the first time there is now also a "G" head on a Lexus V8. This is the 2UR-GSE that's used in the IS-F.


Horsepower ratings are good for these new engines, but kinda pointless to me in the grand scheme of things. What I really want is some detailed photos of some tear downs of these engines.

Edited by Gollum
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Addition - Though the 1UR thus far seems to be a rear sump engine, the 2URFSE pictured here is a mid sump.





Pictures via wiki (always wonderfully reliable......) show the 2URGSE from the IS-F. This shows a rear sump design.



Edited by Gollum
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According to this thread found here:




The 3UZFSE head flows around 300CFM at .5" of lift on the intake side. Seems a little hard to believe to me, and we all know that internet data is rarely full proof. Here's the actual figures posted.


.100" 105.6 - 104.9

.200" 191.0 - 190.8

.300" 254.0 - 257.3

.350" 273.6 - 279.3

.400" 286.2 - 295.3

.450" 293.8 - 305.7

.500" 299.0 - 310.4

The two sets are after he did a "mild cleanup". The fact he lost low end lift sets of warning bells in my head. I'm not a true expert though. Maybe Braap can chime in.

Still though, even if he's 20% off, those are still decent numbers. I should hope so though, considering the head is designed for quite a large cylinder.

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Pending the size of this thing, it sounds like it could be a pretty good candidate.


]The two sets are after he did a "mild cleanup". The fact he lost low end lift sets of warning bells in my head. I'm not a true expert though. Maybe Braap can chime in.


Losing <1 cfm isn't anything I'd worry about, it's so little it could just be noise in the data.

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  • 4 weeks later...

I have never seen any FE UZ heads flow anywhere close to those numbers. If the FSE head really can produce those kind of digits on a UR engine it should be a screamer. I'm guessing from the performance figures even with those quoted head numbers is done with itty bitty cams. This seems to be the case now adays, I'm seeing Merc, Jag, Toyota, and similar go to better and better flowing heads with smaller and smaller cams. Not that this is a bad thing.




And playing with a motor with no aftermarket support just makes it that much more satisfying when it's done, especially with the calls to the tech dept of various aftermarket companies only to have them be like....what's that? You sure that's a real motor? Why don't you just put in one of them supra motors? (Literal question asked to me by an un-named piston company)

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Woops, didn't see my typo before, where I said 3UZFSE in regards to the flow numbers. Those were definitely 3URFSE heads, there's no such engine as a 3UZFSE (unless you want to hybrid, but I don't think those heads are easily swappable).


If the FSE heads CAN flow even 90% of those numbers then serious power can be made for sure. Can the bottom hold it? We'll see.


Which brings me to ~ thanks for the input howlermonkey. I'm always interested to get information from those that work on cars at the dealership level. They see the most common issues first, and are usually the first to know the preferred ways to fix problems.


Any indication as to why they're having valvetrain issues? Poor geometry? Saved too much money on manufacturing? Abusive tune/drivers?

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Carbon is building up on the valve stems which sticks them open on the -fse and -gse (direct injected) versions of these engines.


Since it happens on both of the direct injected V-6, then I assume that it's not a case an injector blowing onto the back of a hot valve since only the IS350 has both port and direct injectors....the is250 has only direct and no port injector.


My theory is that the cam timing wizardry they went through to get rid of the egr system has something to do with it since they use reversion to achieve egr.


Don't get me wrong....the IS350 screams but it's complexity tells me that it will be quite a chore to extract more hp from one.


I did dyno a IS-F that put down 500hp at performance power (owners of the 253mph ford gt) but the factory ecu did what it could to pull power above that.


It might have been trying to keep power down for the benefit of transmission longeivity, though.


I've only been back with lexus (after 5 years away) for a few months so I am still learning what issues we are having with the newer cars.

Edited by HowlerMonkey
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  • 1 month later...

Hey just to let you guys know, Im working on a manual transmission solution for the UR series engines. It wont be long before ill have a 3ur running in my supra, Ive been doing manual kits for the UZ engines over two years now. anyhow here is a teaser of the UR conversion parts if your intrested contact me, www.quantum-auto.com



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  • 1 month later...
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  • 13 years later...

Did any of you move forward digging into the UR engines?! I’m a Subaru guy and through an odd turn of things trying to research more technical info on Toyota UR engines after getting a 1UR Tundra. Now however I’ve found the frustration that I’m spoiled on in depth break downs that are common with Subaru engines. Now I’ve stumbled my way to you Z boiZ who might have dug in more. 

SOOOO what cha got?! I’m mainly hoping to brainchild a flatplane crank hybrid build. One of the Tundra forums I found a thread that was gonna pick up as many UR variants and tear each down but it dropped off and was abandoned it seemed. 

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