Vvti Conversion Question?

[jibby]

I AM CURIOUS AND AM HOPING THIS IS NOT A STUPID QUESTION BUT DOES ANYONE KNOW IF THE 1998 AND NEWER LEXUS VVTI SYSTEM CAN BE CHANGED OUT TO FIT AND WORK ON AN OLDER MODEL PRE 98 V8 LEXUS MOTOR? WHAT IS INVOLVED IF SO. ECU, ETC....

READING UP ON THE VVTI SYSTEM AND THE EXTRA HP IT MAKES ON THE 98 AND NEWER MODELS IS MOST IMPRESSIVE TO ME. AS EVERYONE KNOWS GETTING ADDITIONAL HP OUT OF THESE OLDER MOTORS ARE HARD TO COME BY AFTER THE EXHAUST AND ECU UPGRADES ARE DONE. INPUT ANYONE?

:feedback:

 

[Lextreme II]

You will need a complete block up, wiring and ecu.... I think there are othre ways to get more hp. One thing you can do it to get a 4.3 block and mate it with modified 1uzfe heads. Increase compression ratio from 10.XX to 11.XX by either altering the custom pistons, block or heads. Porting the heads wont hurt either.

 

[Toysrme]

Stop yelling.


Toyota vvt is nothing more than an oil pressure operated camsprocket that advances 15* cam angle (30* crank)

The ECU opens an oil pressure solenoid & the oil pressure makes the sprocket spin in advance.
VVT-i is the exact same thing, but the oil pressure solenoid is pulsed by the ECU - instead of either being 0*, or 30* advance, it can varry any point between them. Converting is just as easy as applying a hydraulic pressure onto a vvt sprocket retrofited to camshaft<s>. The biggest problem is retrofitting them & the cams themselves.
Non vvt designed cams are not going to be nearly as good when advanced. not only that, but most FE heads only have one cam sprocket - when you advance the intake cam the exhaust also advances - which isn't always what you want.

The best thing to do would be make a baseline dyno run, then advance the camshafts 30* to the crank angle & make another dyno. That way you don't waste time & money playing with cams not designed to be advanced.
(You could use a piggyback that can generate a pulse signal to get vvt-i - but that would take some good time spent tuning.)

 

[WDoherty]

You could swap the heads from a vvt-i 1uz and ecu, but the pistons on the earlier 1uz are a different shape, so you might not get as high of compression and it might not match the combustion chamber of the head. Plus the price of these items is high, and and where are you going to find the 1uz vvt-i heads seperated from the engine, these later engines on not really on the market at good prices yet. Overall, you'd be better of swapping the entire engine or engine and tranny (5 speed auto), or it may be cheaper to purchase the later car, a 98 which already has all this done, and correctly. This could be a quite expensive 50 to 70 hp gain and no availability of aftermarket cams to go much past the 300hp mark.

 

[jibby]

Well thank you guys that explains it very well to me. I was not aware that the cam angle created the power, very interesting but makes sense. It sounds like a potential head ache trying to convert the vvti concept into the older engines. Thanks for the input.

 

[Lextreme II]

I think the 4.3 conversion with heads, Jbrady headers and cams mods would work. I think combo will give you somewhere about 350-375 bhp

 

[jibby]

Headers are paid for and on the way from S&S but it's taking along time. I think they have to make them after the order is paid for and in. I Called S&S yesterday and they told me the turn over time maybe three more weeks.

Yeah, boring the engine, cams, 3 angle valves will do the job just fine. I was thinking along the lines of that plus the vvti, but it appears from the above posts the vvti conversion does not seem practical for a pre 98 motor, Thanks