What's the stock size of the tubing on a 1998 4Runner? Just wondering if there is someone that makes a 3" exhaust for our vehicles.

Chris

 

All the aftermarket stuff I've seen is 2 1/2". No 3" yet. Might be something to try in the future.

 

So what's the stock size? 2"?

Chris

 

Stock size is 2.25" ID. Greddy makes a 2.75" ID Exhaust for these trucks. That's the biggest pre-manufactured system that I know of.

Dr. Z

 

They no longer make it or have in stock. Greddy SP exhaust is very restrictive anyhow.

 

I stand corrected. Greddy USED to make a 2.75" Exhaust for these trucks.

I would never have bought a Greddy unit myself. I prefer Borla or Jardine systems.

Hi Zubaltec. Welcome to the fourms.
Dr. Z

 

The fit and looks of the Greddy are always top notch. Our race car and team are both sponsored by Greddy. We are also sell a great deal of there products. Thats why I looked at get a exhaust from them, but seeing as they don't make it anymore and Borla hooked it up Big Time I can't complain. On a side note HKS makes exhaust for the 90-95 as I had on my 90 V6. Very nice piece.

 

Running without a cat makes your low-end torque go to crap. Which in turn makes day to day driveability go down the tube (no pun intended). Unless you are drag racing or running your 4Runner in the Baja, leave your cat on or get a high flow.

Like others said, the performance increase is not worth the harm to the environment. Ever been behind a car that has no cat? Dang that stinks!

 

So, if this is the case, what is the best high flow(best flow rate, least restrictive) catalytic converter? I know and easy way to increase the low end again, and that's by getting a smaller pulley for the S/C.

Chris

 

Just a side note:

SCC did a test on some high flow cats on high revving 4 bangers, a rotary, and a MR2. If I remember correctly, they actually lost HP with the "high flow cat."

Even they were surprised.

I dont think high flow cats are all they are cracked up to be. Not like anyone would catch you, but removing your cat if its not defective for any reason is a federal offense. Not like that ever stopped anyone.

 

How much more low end do you want I'm already spinning the tires? There was another post about a brand new '02 w/ charger that melted the cat. The motor took in some of the debris. This happened to our F-150 and costed us $5000 for the motor. I don't really feel like replacing my motor. After I remove it I'll post the dyno graph and we'll see if it's worth it. Have you even driven behind a diesell truck now that stinks.

 

Do you know this from experience on an SC'd truck, because I have not found this to be the case?

On my 98 SC'd 4Runner I have noticed no ill effects to performance, in fact just the opposite, it's a lot better at all engine speeds.

 

The only real reason that I would do it is if I in conjunction with the high flow cat, I would also get the smaller pulley. The reason for this is that I read that the increase backpressure that the stock exhaust provides boosts the stock pulley boost 1-1.5 psi, which means that when you go to the high flow cat, the boost is going to go down, and as a result so is your power. Or at least, that's te reasoning that I'm using.

Chris

 

FattyCBR so has your boost gone down?

 

Yes, I ran around for about 5 minutes open header and it went down about .75 psi, with the test pipe in it has gone down about .5-.75 psi. It revs so much better now and I can hit the speed limiter much easier and in 3rd gear.

My only beef with the test pipe is it makes the exhaust note a little higher and a little louder at all engine speeds. I'm thinking of putting a silencer in it's place, but that will be a little while away.

 

So you spin the tires in third gear at 2K RPM's merging on to the freeway? I wasnt referring to launches.

Diesels do stink, but so do cars without cats. I dont see how mentioning diesels detracts from the stink of engines without cats.

I know we are talking about larger displacement engines here (compared to the 4 Bangers I mentioned). Again, it was just a side note. Maybe there are people looking in on the thread with the 2.4 and 2.7.

Please do show us all the dyno runs. 3 with a cat, and 3 without a cat, and then the delta. I would like to see what this does to a SC'd 3.4. BTW: I dont disagree about a gain in HP. I am truly curious.

I would also like to see the long-term ramifications to the engine. But, that will take some time (obviously).

 

It all goes along with people talking about how they don't like big turbos cause they take for ever to spool up. Well if you down shift just as my truck would do if I stepped on it at 60mph you'll be back in the power band and take off. Not trying to be a jerk just explaining myself.

 

Basically, the less backpressure the less boost. Milan, what are you running now?

Chris

 

I guess it all comes down to what each persons needs are. I dont want to lose my low-end, of course I am not SC'd. Maybe my views would change a bit with the SC (in fact, I'm sure they would).

Keep us posted. I was always under the impression that backpressure was good with a SC. Turbo, now that's a little different.

 

I'm just a little over 7 psi.