20lex20

I have an 02 GS300 and have put on a weapon R intake and Im getting ready to install the new underdrive pulley on. Will I have to add an exhaust to get max performance out of the intake and pulley, also does the computer automatically adjust for the performance mods. After I put the intake on I noticed my car sounded like it was choking from too much air. Is there anything I can do to fix this, or is that normal. Any help or info would be great. THANKS

ILOVEGIRLS

iTrader: (3)

the underdrive pulley will "free up" more hp across the rpm band. there is a downside to this mod although i am not sure if it applies to lexus. most underdrive pullies are harmonically balanced. not from experiece but if the pulley is not balanced properly, it can lead to premature or uneven engine wear. anyone else know about this?

the theory is: the engine was made to handle X weight on one end and X weight on the other end of the block. if for some reason X weight on one end is lighter, it changes the whole balancing act that was meant to be there in the first place. hopes this makes sense. i never used an under drive pulley because of this. i dont want to find out later that the underdrive pulley ruined my motor by unbalancing it. my last motor that was built was blue printed and balanced with the aftermarket parts.

JBrady

Actually, the key word is HARMONIC balancer/dampener. The reason is NOT unbalanced components. The reason IS that every firing of a cylinder actually twists the crankshaft out of shape (very slightly) and then it literally SPRINGS back again. This creates a harmonic in the metal of the crankshaft. Remember, EVERY time EACH cylinder fires on the power stroke this happens. The combined effect of all the twisting and springing harmonics is stressfull on the metal. Just like you can break a heavy metal wire by bending it back and forth these harmonic stresses will eventually break the crankshaft. Even before it breaks it will cause some damage to other parts such as bearings.

The harmonic balancer/dampener absorbs a large amount of these forces and loads. It is DEFINITELY needed. The damaging effects are highest at certain RPMs but exist for the full RPM range. There are a FEW quality aftermarket underdrive crank pulley that have the dampener built in. If the part you buy does not have it... don't use it.

ILOVEGIRLS

iTrader: (3)

nice info. im glad someone here on the board was is able to explain what i couldnt.

20lex20

Thanks for the help. Im not trying to destroy a car that I just bought. The pulley that I have" BOMZ" doesnt have a dampener. What do you feel is the best bolt on aftermarket part that will increase HP with out damaging my engine. I have the weapon R intake. Should I put the BOMZ pulley on the back burner until I get more miles on the car and just put an exhaust on it. I know someone has put an intake and exhaust on a GS. What is the typical HP ganes you can get from this. THANKS FOR THE HELP ON THE PULLEY< IM STILL NEW AT THE GS MOTOR.

ILOVEGIRLS

iTrader: (3)

i would look into a header. ive called a few companies and they suggested the OBX header. LMS uses the OBX header along with their supere chargers. their is also another company xerd(sp?) that also makes headers. i dont know which to go with since ive never heard of xerd until recently and OBX..i thought they were a "generic" brand. so far i have not been able to find any dynos or anything. good luck.

JBrady

Best? TURBO

That said, naturally aspirated gains are tough to come by. I think a torque converter upgrade would be your best bang for the buck.

Lexizm

iTrader: (2)

You can try most headers for the IS300. It's the same motor and should fit the GS. I heard that the Xerd headers for the GS and the IS are very loud (too loud). I have the OBX on my GS and I'm glad I have em. They sound wicked with my Carson Tune exhaust. I have a friend with an IS that have some Xerd header, and his car sounds loud especially wide open. Go with a set of headers.

ILOVEGIRLS

iTrader: (3)

do you have to modify anything for the OBX header? did you feel any difference in regular driving speeds?

20lex20

Everyone is saying go with a header which I now will. Should I leave the stock cat back exhaust on or upgrade to a borla or just get a set of after market mufflers. Which is the best setup to run that gets max HP but doesnt sound like your driving a KX 250. Thanks for all the help. Also where can I buy the OBX header.

ILOVEGIRLS

iTrader: (3)

i have only seen the OBX header on ebay. you might want to call luxury motorworks to see if they have any.

Hollywood

Underdrive pulleys=the enemy,

I would never use one ever. U can get away with it, but later down the road you may see the front and back seals start to leak and possible worse.

Lightened flywheels is less of an issue tho if ur standard.

Lexizm

iTrader: (2)

I didn't have to modify the headers at all. They bolt right up to your B-Pipe. I did feel a differnce, but it will start at the mid-range to high end. I do a lot of highway driving so that's my daily drive. You will probably won't feel it with the around town drive.

I almost forgot, you will need some SIMS or Emulators so you don't get the CEL. They don't have cats

Lexizm

iTrader: (2)

I would go with a upgrade to Borla to get the best HP gains over the stock exhaust. Also Borla is not loud. My friend just got that exhaust on his IS and he said it's quiter than his HKS system and I can confirm that one. I'm trying to find the link to the OBX headers.

RRocket

I have used underdrive pulleys for many years in many different applications, including DOHC V8's. In all my years of using them (including my friends using them, including me nearly living at the drag strip) I have never, ever EVER seen an engine failure due to underdrive pulleys. The worst thing I've ever seen happen was a dead battery from a swapped alternator pulley. If there was an underdrive pulley for my GS400, I'd use it...