Help need Lexus SC400 performance pulley system

[WUKWS]

Does anyone know if there are any performance pulley systems for the 1995 SC400 Lexus if you are not going to put in a charger or a turbo?

 

[Lextreme II]

Its being made by Team Lextreme as we speak. Two pullies are in the design process. NA and Supercharger Pulley.

 

[WUKWS]

thx for your info, I am anxious to see them

 

[Peewee]

What is a performance pulley?

 

[Lextreme II]

It will be lighter and smaller. Lighter will save some energy and smaller will save the life of accessories. I would say about 10-12 hp.

 

[Peewee]

I would say about 10-12 hp

I would say you are dreaming.

Compare the stock crank pulley to other Toyota pulleys, it is already very lightweight.
I'd say it would weigh less than half of a 7MGE pulley.

I would guess 5hp would be a maximum on a stock engine.
It would rev quicker (slightly), but would make stuff all extra power.

 

[Lextreme II]

Stock pulley is made of casted steel. We will make it out of aluminum.

 

[Peewee]

Yeah, but you're talking about taking 2lbs out of a rotating mass that would weigh inexcess of 150lbs.

And that 2lbs is 2" from the centre of rotation.

Gains not worth the cost in my opinion.
Not on a stock motor.

 

[xirforever]

Peewee

I think you are missing the whole point.....
The point of a smaller pulley (aka underdrive pulley) is not to be lightweight, although it is a plus... it is to slow down the speed of the accessory belt, therefore saving parasitic energy.
If you think about it in terms of ratios of pulleys... if you make the main pulley smaller in diameter you are making it turn more times to creat a full rotation of the belt. In turn that relates to the engine spending LESS effort to turn anything on the accessory belt. Less effort spent equals more HP gained.
Do a search on the internet. Making it out of aluminum is only a plus, i mean if we are going to make a new pulley, why not make it lightweight as well?

Just my 2 cents
Nick

 

[Peewee]

So you guys are all gonna need custom length belts as well?

And your alternator will do sfa at idle?
As will the aircon?

Sounds like a real benefit to me

 

[xirforever]

You obviously did not do the search on the internet like i suggested.... I know people who have put in underdrive pulleys in their cars;

1.) You DONT need a new belt, tensioner will pick up slack
2.) Unless you have some crazy sound system runnin with like 1,000 watts on just subs and have it on full blast with heat seaters on, ac on full blast, while on IDLE, you should be just fine...

So yes, peewee, it does sound like a real benefit to me.

 

[sniper]

Running this type of pulley is very common in the rest of the performance world. After this one of a kind pulley is made, we will see first hand the pros and cons of this common modification

 

[Peewee]

You DONT need a new belt, tensioner will pick up slack

So you're only reducing the circumference of the pulley by a few mm?
The tensioner picks up about 40mm of belt length.

I know this because I am using a different belt to stock as I currently don't have an A/C unit.

The first one I ordered was 1710mm long, the tensioner only just couldn't pick up the slack.
The 2nd one I got was 1680mm long, the tensioner is almost at the full tight.

I doubt I could get a 1670mm long belt on, and I definately couldnt get a 1660mm belt on.


Anyway, all that aside, reducing the alternator and powersteering rpm by 20% (presuming you make the pulley 20% smaller) will save you SFA power.
Like 2hp per unit.

You'd have half the speed of the ancilleries before you will notice anything.

 

[xirforever]

Good info on belt and whatenot

But if you figure id have to reduce speed by 1/2 also meaning that the accessory belt will be twice as easy to turn, to notice any power gain, how do you explain all those underdrive pulleys on the market that dont reduce speed in half and do make a noticable difference? I know from three people who have installed these saying that they helped out in the low end power noticably... what do you make of this? i guess well just have to wait and see.

 

[Peewee]

What do I make of that?

I'd say it will work on a 4cyl, free up a few hp there.

However, on the 1UZ, with its increase capacity, and thus torque, and increased moment of intertia (I think that the right term, basically increased rotating mass), you will notice a very very small increase in power.

Take a 4cyl NA, putting out 160hp.
I can see maybe 10hp from a smaller pulley, so 170hp.
Thats a 6% increase.

Take the 1uz, putting out 280hp.
I honestly can't see more than 5hp, but lets assume it does get your 10hp.
Thats only 3.5% increase (1.8% @ 5hp).
I don't think you'll notice 3% increase on a 1UZ.

You'd be getting more drivable results from a better cold intake, or a freer exhaust.

Its a pity you stock guys can't dial in a few more degrees of timing, and run a higher octane fuel. Because that would definately net you 10+hp.

 

[Peewee]

But if you figure id have to reduce speed by 1/2 also meaning that the accessory belt will be twice as easy to turn

I haven't tested anything, but I doubt that speed vs drag is a linear graph.

 

[xirforever]

I haven't tested anything, but I doubt that speed vs drag is a linear graph.

Its not speed vs drag... i think it all has to do with ratios, if im doing my math right... If it takes the pulley twice as many times to turn the belt that should mean it is twice as easy to turn.. i could be wrong tho. When your riding a bike, say the gear ratio is 1:1, that would be VERY hard to pedal, but if you make the pedaling gear 1/2 the size this should make it twice as easy to turn... can someone confirm or correct this?


Ive been doing some thinking also, i was thinking about doing an underdrive for the crank pulley, althought ive been doing some reading and a lot of sites say to stay away from those becuase the crank pulley is needed as a harmonic balancer... Anway underdrive pulleys could be made for alternator, PS pump, and water pump, as all of them are putting out more than they need at times, mainly when your driving, at least im pretty sure from what i read. Anyway the guys i were talking about who saw a difference; one had a 5.0 mustang and the other had a 93' M3

I think it would be interesting to do a before and after dyno.

 

[Zuffen]

A performance magazine in Australia experimented with smaller water pump pulleys and yes they found a couple of horsepower by slowing the waterpump but lost out in cooling.

As the waterpump is the biggest draw and we can't change it's ratio there's nothing there.

An alternator has almost nil drag when it isn't actually charging so next to nil there.

Air con. Put a micro switch or MAP switch on the throttle/manifold and turn off the air when you go WOT. Again near enough to nil there.

This leaves the P/S pump. It will absorb a max of 1HP when not turning the steering wheel. Again insignicant gains.

Unless you plan on making pulley's for the air co, alternator and P/S I wouldn't bother.

As for all the people with underdrive pulleys who said they work? Where are the dyno figures?

Why do people instal different air filter systems that are proven to cost HP. Because "everyone else has one". On that basis I'd have a pieced ear and eyebrow " because everyone else has one or both".

The harmonic balancer is a sophisticated device (that looks simple) and it shouldn't be messed with unless you can build one that works.

 

[xirforever]

Zuffen,

If we were to make a supercharger pulley attached to the crankshaft pulley, but make a whole new pulley with all this, not just bolt it on, how would i keep the new one acting in the same harmonic way as the old one? Do i just keep the weight the same? (OEM is 6 lbs)

 

[xirforever]

This guy says that for every pound taken off the rotating mass its equal to adding 2.7 HP. Here is his little write-up
http://www.ttzd.com/tech/pulleytech.html

Here is his dyno to proove before and after. Pretty big HP gain in my eyes (11 HP)
http://www.ttzd.com/rides/dynocharts/dynochart33.jpg