safe power for LS400 vvti 5sp autobox?

[Skullface]

Its a 1998 vvti Ls400, I want to charge it, but keep automatic tranny. I have a bike for grabbing at gears, just want the LS to be a smooth beast.
It has the later 5 speed box, what kind of power can these take before destructing?
I have the option to put 20psi boost into this 1uzfe-vvti so need to check the goalposts first...

Cheers all.

 

[spf_lexus]

The trans should be good up to around 350rwhp before destruction occurs. Shift kit + kevlar clutches + cooler will raise that another hundred plus. Ask Steve Chumo, he recently built his a340 (4-speed) to handle high boost. The motor will also be about to blow at 350rwhp unless you build the block. The rods are time ombs when under boost. 20psi will require forged rods + pistons + standalone + custom fuel system. Basically a built motor and trans will be needed to support 500rwhp (ish) from 20psi. What blower are you looking at?

 

[Skullface]

I already have the charger, from a late model AMG Merc SL55, 20k miles IHI Japan twinscrew Lysholm unit, Has a waterpump built into the nose and a charge cooler unit strapped underneath. Can get to my garage and take a shot of it if it helps? its huge, really needs a 6l engine to use it, but I heard the 1UZ was a race bred engine good for up to 560hp on stock internals and so I now have a LS400. I was under the impression that 1UZ had forged rods standard, but not strong enough pistons to cope with high boost? I was expecting to go down the Megasquirt ECU route.

 

[spf_lexus]

The early 1uz's have the bulletproof internals (1990-1994 motors) and everything 1995+ has the weak rods. If your looking for 500+ hp, your better off sourcing an early motor unless your willing to build a later model motor and swap early model rods. Your megasquirt should be plenty for tuning it though.


Post a couple pics of your MB charger it will help. Its interesting to hear the blower has a built in pump for cooling. You can run the coolant lines for the blower into the factory A/C condensor for an easy solution or add another one (sandwich style) to keep the A/C.

 

[Skullface]

the later model has vvti which makes it quite a bit more powerful.. when supercharging, does the VVTi advantage matter less? or would it be well worth using a '93 block and a VVTi head with a SC. cheaper obviously just to use a nice low mileage 1993 engine.

I will head to the storage in a few days and get better pictures of my SC, but for now, this is a similar unit (poss same) you can see on the pulley end 2 or 3 pipe stubs heading out the end cap, down axis, aluminium, about 5/8" diameter. Same colour liquid flowed from those pipes as from inside the charge cooler.. same unit as pictured there with brass hose stubs protruding.

 

[spf_lexus]

the vvti heads wont swap onto an early block, only because of the VVT oil feed ports that must line up between the heads/block wont be there. You will make more hp/PSI of boost on the vvti motor but as stated earlier, you will need thicker rods as a bare minimum. You can still run the blower w/ a stock motor but 6psi or so is going to be your limit. Also, the 1990-1994 OEM rods swap right in and can be found a lot cheaper than custon rods. Lextreme makes modified Chevy H-beams that fit the late models are are decently priced, and will support high hp/boost.

 

[spf_lexus]

Check these out:

http://www.lextreme.com/Toyota-Lexus-Rods.html

 

[Skullface]

Okay I'm with you now. The early rods do look a lot stronger and according to whats written about them will be plenty strong enough for my prospective whp.

There is a post here about upgraded billet sprag clutches for 650 gearbox, is that the box i am likely to have in my LS. Unlike the owner of that post, I dont intend on shifting at 8k rpm or drag racing, and hope to get 500hp or so as a usable daily driver.. are the fancy spraggs needed?

and here is the link i seem to have missed off my last post, some shots of the charger i have in its teflon coated goodness.
http://www.retrocarclub.co.uk/forum...s-highly-efficient-lysholm-type-supercharger/

 

[spf_lexus]

The a650 is a 5 speed version of the a340 4 speed w/ overdrive. The units are essentially the same except that the early models use a mechanical line pressure cable and the 5 speeds are electronically adjusted. Regardless which unit your running, they both have the same hp limits of 350RWHP. I would throw a large t-cooler on it, syntec fluid, shift kit and some raybestos kevlar clutch packs, those in combination should hold up 500BHP (or so).

Your biggest enemies with your auto is heat and shift lag. The shift kit and cooler are the most important.

Steve_Chumo has names + prices for these mods. He rebuilt his with all the parts listed and he puts down 400WHP which is a hair under 500BHP.

 

[Skullface]

I think my conufsion is that there might be a 350 and a 650 gearbox. I do have a 5 speed box thats for sure.

I hope to get to 500WHP sorry for the confusion there. A charger like that would be a little wasted otherwise.

Thanks for all your pointers SPF (y)

 

[spf_lexus]

No worries, thats why I love this forum, no BS or fluff, just the raw facts.

I do have a 5 speed box thats for sure.

Then you have the 650, and yes like the 340 series it will require modification to work day-in day-out. The transmission should be fine if you do your homework. And the 1uz should be able to put down the numbers you want relatively easily if you invest in a quality tune/standalone. Forum member Justin_GT8 made over 500whp on a completely stock/unopened motor w/ twin turbos at around 20psi (maybe a bit less) and his ran for years w/o a hiccup. This guy at one point ran twin turbos as well as an eaton m90 for a twin-charge setup but the heat/compound boost was just too much to control.

Also, Neil Griffiths in AU is putting down 400whp on a completely stock 1uz with a whipple on top.

Boosting these engines are fairly easy, its the tune/tuner that makes it a PITA

 

[Skullface]

Well if i work to 500whp.. can always redo the project later if needs be and tune/changeout for higher.

I have tried to have a good read around to answer my own questions, but I think all I have acheived is confusion. Seems a lot of my issues come from this being a VVTi with a later 5peed tranny.

here goes.,.

This later 650 5speed, is an electronic/hydraulic actuated unit, not mechanical like the earlier ones?? does this affect the recommendations of 'shift kit' and do i still need kevlar plates to get to 500whp, or will the larger autofluid cooler be sufficient.

Tuning, I was always intending to go Megasquirt2 (or3 if fully ready at buy time) I have some familiarity with tuning ECU's on propane gas conversions and I tune my own bike carbs. I have the Tech Edge 2Y1 WBO2 kit and display to aid there.

Justins and Neils motors, I guess were the early 90-94 blocks with the stronger rods? The VVTi thinner ones are no good for 500whp?? Nice to see they are managing this without special pistons or even machining to a lower compression.

 

[spf_lexus]

Sorry for the late reply but yes, you WILL need stronger rods at a bare minimum to support any decent amount of boost. Your trans is closely related to the e340 trans, just an added gear. Boostlogic I believe makes kits for rebuilding your 5 speeder. Try a google search with your trans code and im sure you'll find a few companies catering to your auto box. As for Justin and Neils motors, yes they strictly use 1990-1994 setups. If I were you with the interist of keeping everything as is, swap your rods for stock 1990 rods or use Lex's chevy H beam rods which you wont max out. They are massive! Tie everything together with ARP head, rod and main bolts, use Cometic multi layer head gaskets and find a good tuner. Those should be plenty to hold 500whp. Keep us posted on your progress..