motorheaddown

Just a heads up for 2jz VVT-i owners running boost. A few months ago, I was part of a thread on IS300.net concerning the IS300 VVT-i rods and pistons. Freelance posted pics comparing the IS VVT-i rods to NA Supra rods. The rod/piston differences are eye-opening: http://www.is300.net/modules.php?nam...834&highlight=

I was reluctant to post these findings over here until I had solid proof that it could also effect SC/GS VVT-i motors. Unfortunately, I now have the verification. A SF friend (Carchitect) who lives in the DFW area is a certified Lexus mechanic, and I asked him to make note of any GS/SC oil pans dropped at the dealership just to check for the weak rods. In every instance, VVT-i motors had weaker rods and pistons with shorter skirts. He's done quite a few GS/ISs but no SCs. However, there's a good chance the SC VVT-i motors share the same fate.

Apparently, not all 2jz motors are created equal.

-scott

FWIW, I believe the rod that is bent in the photo experience hydro-static lock (injestion of water in the cylinder). Consequently, rod failure under moderate boost is unlikely. However, it's unknown how durable the weaker rods are.

awj

kmn5

very interesting,
kinda glad I don't have the vvti now

Richie

If you want to go the FI route, isn't it safer to get a TT bottem end to be safe?

motorheaddown

This has been discussed a bunch of times. The non-VVT-i 2jz-ge motors share the same block, crank, and rods as the TT short block. Read the last paragraph: http://www.mkiv.com/specifications/ncf/ncf93/ncf080.jpg

A search here and on SF will produce a myriad of threads that have already discussed this.

-scott

Lex Luthor

Not to burst your bubble Scott, but this is not news, I assumed most of the engine savvy guys here knew but i've mentioned it several times anyway. I'll of course jump in on the side of VVT-i, since you know how I love a good debate Scott. Many, not necessarily you, make this sound like it's a death knell for NA-T guys with variable valve timing, like kmn5 who said 'glad I don't have VVT-i now.' I smirk to myself reading that. It's technology guys...it's good. The reason the rods and pistons are weaker on these motors is because they are lighter, the VVT-i 2JZ's are designed to rev faster and freer. At moderate boost levels it is not a problem and presents many benefits for turbocharging, you can run a slightly larger turbo because it spools quicker. Yes it removes about 100 hp worth of capability out of the reciprocating assembly, they're good to about 500 rwhp, but several have pushed it to 600+ rwhp on the stock VVT-i bottom end, I believe the pin is most of the way out of the grenade @ this point. You can of course swap in TT rods and pistons, go aftermarket, or drop in a GTE short block when durability starts to become threatened, but for an everyday drive-it-to-work car, it'll be perfect. I've got a semi-decent pic of the VVT-i mechanism and some other pcs in my SP63 thread if any of you are curious. I'll definitely let you know when I reach the limits of the short block Scott, all in the name of research .

- Jon


Hey, anybody got a stock TT exhaust cam lying around?

motorheaddown

Jon,

No problem... I enjoy a good debate. Plus, I basically agree with all your points. As mentioned in my first post, I think the rods will hold up fine to moderate boost levels. However, I wouldn't build a monster motor on the VVT-i shortblock. However, the benefits to VVT-i are definitely worth having.

-scott