iasc300

iTrader: (1)

The ignition system on your car has to work in perfect concert with the rest of the engine. The goal is to ignite the fuel at exactly the right time so that the expanding gases can do the maximum amount of work. If the ignition system fires at the wrong time, power will fall and gas consumption and emissions can increase.

In order to get the most torque and power from the engine, the goal is to maximize the pressure in the cylinder during the power stroke. Maximizing pressure will also produce the best engine efficiency, which translates directly into better mileage. The timing of the spark is critical to success.

The spark plug is quite simple in theory: It forces electricity to arc across a gap, just like a bolt of lightning. The electricity must be at a very high voltage in order to travel across the gap and create a good spark. Voltage at the spark plug can be anywhere from 40,000 to 100,000 volts.

Sly Guy Yu

Yea, the 98+ do.

over40driv

Ok so what makes the Bosch fusion so much better, and would they be recommended for a 95 sc400?

iasc300

iTrader: (1)

The options for new spark plugs are endless- there are many factors, even if your vehicle is not highly modified- keep in mind - you would also need bigger ignition cables or wires (8.5mm)-(10mm) if you will to handle the high voltage - they are also made with many different types of precious metals- depending on what meets your needs- i believe the most common spark plugs electrode is made out of nickle???? but they can also be made out of chrome, manganese and silicone, and even platinum and iriduim. Also depends on your air-to-fuel ratio- which should be around- 14.7:1 -

Solarian

Please don't spread incorrect information. Running at 14.7:1 aka stoichiometric is dangerous, absolutely disastrous on a turbocharged vehicle, less so on a naturally aspirated vehicle, but still dangerous nonetheless. The only known exception to this is the direct injection motors on the new IS, which can actually tolerate stoich and even leaner than that when under light load, however, they also rich out under heavier load, because it is unsafe.
Furthermore, running bigger ignition cables will do absolutely nothing unless you have an upgraded ignition system, like for example an MSD or the like.
Also, generally speaking the best performance and fuel economy will be obtained from running regular copper spark plugs, and changing them at regular intervals, rather than the fancy iridium stuff. It's also a little bit cheaper too. The NGK V-Powers are especially good.

iasc300

iTrader: (1)

whoops i said not highly- i ment to say highly modified- if you run a higher voltage spark plug you are gonna need bigger wires to handle the voltage- you are making a big mistake if you upgrade and dont upgrade your ignition system- am i wrong? goodluck running a high hp vehicle with crappy plugs- do what you will with your engine- i was just adding my input- but i wish you the best with your engine and **** plugs

sorry no more thead jacking

over40driv

Yeah my fault for jacking the tread, I just did a 300 mile autotrader.com search for 98-2000 sc400 up to $14,000, got one car 98,000 miles with aftermarket wheels.

1JZ300

iTrader: (6)

nice color.....welcome

JLSC

Good find! The red/tan combo looks really nice.

98LexSc400

Devir

Just wondering why you bought magnaflow cats for your car? I can't believe yours are bad with under 70k on them. There have been some test's on the metal matrix lexus cats on these cars are they are really efficeint and are hard to improve much over. The Magnaflow's are made by car-sound not bad but your money would be better spent elsewhere. Check out Random Tech http://www.randomtechnology.com/products.html and any of the other companies that make a metal matrix style convertors they are the only true performance convertors. The 1998-2000 SC400's only have 2 cats the center section with 2 pipes going into it is a resonator and this is followed by 2 more before finallt reaching the rear 2 mufflers. I have pictures somewhere of the underside of my 98 before and after since I removed my center resonator and rear resonators and had a custom h-pipe made to connect from the factory cats to the rear factory mufflers. Picked up good power and sounds great. Just a suggestion for you there are a few of us that have done this its cheap and and the gains are deffinetly worth it. Have fun with the car, I have had mine over 3 years its been great but I have it up for sale now.

jgscott

iTrader: (1)

I tried to tell a couple of people this before. It's true. The Lex Cats are Metal substrate. Only thing better you can do is get a better flowing Metal substrate Cat.

Devir

First off, when i bought the car in VA and drove it home there was a horrible shake in the car. the Lower control arm was stripped so I had the bolts replaced at a Lex dealer. There is still a little shake between 75 and 80MPH but not as bad, Even though the alighnment and tire balance have been done.

The breaks were HORRIBLE for the first 2k miles. Possibly because the car wasnt driven for a while. They're better now that i drive it daily. I'll get slotted/vented disks in the future.

As for the plugs, when i buy a used car, even if it's from a dealer, I replace the air filter, get an oil change with Synth and replace plugs. You dont know what parts they used, nor if they ever replaced parts. In my case the Sparks were originals. After 8 years, it's good to replace regardless if they're at their milage or not.

The car now idles smoother, has more fuel economy and runs quieter since i've changed the oil and put in the new sparks and Fram air filter. It's at a happy point now.

The plans for this car are to replace the exhaust with Magnaflow parts for more flow. But i want to keep the car as close to stock quiet as possible with extra performance gains.

I'm planning on the Dragon Torque converter.

also I want to swap in an LSD. the only readily available option i see is the Kaaz DAT3020 1.5-2way LSD. I would love to put in a Supra TORSEN but they rather hard to find.

After these 3 items are installed, i'll look into super sharging. But for now, the gains should be more than adequate.

Also the body needs some work. there are a few scratches and paint chips along the car which is expected. I'll work them out after winter is done.

sc250tt

nice cars guys .welcome to cl enjoy

Jonathan o

Good to see more vvt-i on this forum.

Devir

I traded in my 2001 Celica GTS for the 98 Sc. VVT-i is a great tech so I knew that was what I wanted.

Problem with VVT-i is it's completely designed to spite you. With older engines you drop in a new air intake and exhaust and you get a great performance increase. With VVT-i you still get a nice increase, but after the engine "learns" what's happening in changes the timing on you.

I'll be hanging out in the engine/exhaust forums now to learn how to modify my exhaust and intake system. Though i cant for the life of me find the exhaust specs and measurments for my stock exhaust so i can start buying parts.