Dr. Zhivago

That's exactly it, although you probably gained some low end power too as evidenced by the new found ability to spin the tires. It won't be an earth-shattering difference. No exhaust system on a properly running Normally Aspirated engine is going to be. Turbo-Charged engines are another subject altogether...

Here's a chart detailing what I said in my last post:



As you can see, for the 3.0, 2.25" is probably best, but 2.5" isn't going to be a deal-breaker.

Hope this helps.
Dr. Z

EDIT: I wanted to add to this by saying that mostly what NWOR is referring to regarding tubing sizes and 2.5" being too large is for the 4 bangers like the 22R, etc...

EDIT AGAIN: I also wanted to add that you should think about re-gearing if you want more torque off the line. I know it's expensive, but it would give you what you are looking for.

zedex

I think anyone modifying their exhaust system is making a big mistake. In most cases people stick a high flow muffler or cat on their vehicle thinking they will get an increase in power.
A motor needs to be balanced. Its a living breathing machine. . You cant just open up the exhaust and expect a power increase because it now free flows out the backend.
I doubt very much that you will see any increase in power and torque by modifying your exhaust system and still use your stock exhaust manifold. Infact i would bet that everything will suffer. fuel efficiency, power, torque.The only difference you will feel is a placebo effect from the extra noise. Everything is tuned at the factory for optimum performance and fuel efficiency. Now good headers and exhaust are a different story.

Dr. Zhivago

That's a good one. If you seriously believe that, I have a bridge you might be interested in.

No offense dude, but that's just not true in most cases. Sure, the stock exhaust manifolds are restrictve, but a properly built and tuned exhaust system with MANDREL bends does improve power and torque. Simply slapping on a muffler doesn't quite cut it IMHO, so I agree with you there.

And, if you're going to the trouble of opening the back end, you really should make it easier for the engine to draw in air by opening up the intake as well.

I went the route of installing an entire cat-back exhaust with mandrel bends and opened up the intake on my truck. Since I can now break traction pretty much at will in 1st and 2nd gear, and even in 3rd gear when it's wet, I know that it's not just a placebo effect.

Speak with an exhaust specialist like I previously mentioned to someone else. I think you have some misconceptions about engine tuning and the importance of the exhaust system.

My .02
Dr. Z

DrtRunner

Ok- its me again, the guy with the original question.
I have an up date to this thread.
Good news.
First Dr.Z is correct- and I agree with him and the guy who said its the boost from 3k up that throws off you perception of the gain in the low end.
Today I finally had a chance to advance my timing, and wow what a difference.
While I figured this would make an inprovement I did not realize the difference with the new exhaust.
So I here are my findings.

1. The 2.25 exhaust infact does increase horsepower- both low end and high end. Although it is most noticeable at the high end. The motor actually "feels" like it can be shifted at a higher RPM.
Definetly increase power at 3K RPM.

2. To gain the low end we all want a simple advancing of the timing to 12 degrees makes a big difference when combined with the new exhaust and cat. Now the most feels very responsive, and accelerates much better.

3. Now all that needs to be done is a increase in air into the motor.I am now considering the options. I have looked at the K&N FIPK kit but the price is alittle high. I think I am going to be building my own intake set-up similar to the ones outlined in the Tech section.

I'll post my findings- I have access to a Dyno and my even give it a run.

Should be done with the intake next week.

Dr. Zhivago

Right on DrtRunner!

The timing advance is a really nice thing for those engines. The factory leaves a really large margin of saftey in their ignition curves for a variety of reasons. Giving it 2* more advance isn't enough to invite problems, but it sure does help with oomph and responsiveness.

I look forward to seeing some dyno results, but mostly I'm happy for you and your rekindled interest in your truck.

Peace!
Dr. Z

DrtRunner

Dr. Z,

I have been running 94 octane for a long time.
Do you think I could advance it to say 14 degrees if I still dont hear any pinning- what might the negative effects be?

Dr. Zhivago

If you're really serious about getting the most out of the engine with regards to controlling timing, get an SMT-5. Since the initial timing on that engine is going to affect the overall curve, 14* might be okay with 94 octane. I don't know for sure since there are so many variables. You could always try it and see.

But if you have $250 or so, get the SMT-5. You can also adjust fuel with it and tweak the engine even more. Since you're considering mod'ing the intake as well, the SMT-5 can really help you wring out the last bit of performance. It's a great little box. I'd even help you with the install should you go that route. Of course, it'd be thru email or on the phone.

Hope this helps.
Dr. Z

DrtRunner

Dr.Z,

I've been considering the SMT-5 but from what I have found a laptop is needed to make this work.

I only have a desk-top computer.

Can I run a SMT-5 with a desk-top? Or is real time programming only?

Dr. Zhivago

Well, you could modify some things with the desktop hooked up to the SMT while the truck is parked. The ignition needs to be in the "on" position in order to communicate. The downside to not having a laptop is you can't tune while driving, which is really the preferred way to go if you aren't going to dyno-tune it. But, if you choose to dyno-tune, then the desktop will be perfect for that. You'll just have to bring it to the dyno shop with you.

I gotta bail for a while. I'll be back later if you want to continue this.
Dr. Z

ManyMods

I find this to be a really interesting thread and I can relate to a lot of the observations even though I have an '02 4R. Given the discussion about exhaust system design and its effect on performance (TORQUE), I want to say that the FLOWMASTER tech department is a great source of knowledge. These guys aren't like the idiots that sell Hypertech tuners; they really know about their product and the science of exhaust system design. I will call them if I don't get an answer to the question I am about to ask ... again.

Has anyone installed Headers and NOT changed the OEM exhaust system? What was the result? I think this could be a very positive modification.

Dr. Zhivago

Peter,

There is someone who has done that. Check out this thread: https://www.yotatech.com/forums/show...&threadid=8664

He hasn't dynoed, but he does seem to like the performance of the TRD Headers on his NA truck.

Cheers!
Dr. Z

williemon

Ok. Its getting a little clearer to me. I sure can understand about the 2.5" on a 22re. On the 3.0s it seems like doing ANYTHING that makes it breath better only works well from 3k on up. The thought about bumping the timeing up by 2 is thought provoking. I might try that myself. As far as adding the smt-5. that is something Id love to try, but my funds are...uh....EXAUSTED!!!

Ranc-0

Hello,

First timer at this forum. I have a 2001 2.7L Reg. cab 4x4. I am looking to increase hp by 20-25 if possible. At 150 horses, it has just enough oomph- but a few extra horses would really help when I am driving up the mountain passes (I live in Colorado).
I know about the S/C for this, but it sounds very hit/miss from what I read.

I would not like to lose low end if possible. This is what I was considering:

Exaust - Header, and high flow muffler (or catback), leaving the rest of the stock piping and cat on.

Intake - Deckplate mod, or FIPK.

Does this sound like a good idea- is the intake and exhaust balanced enough here? The rest of the engine would be stock.

Or does a full new exhaust from header to tailpipe with a high flow cat (keeping stock pipe diameters) sound better?

Any imput would be appreciated.

Ranc....

zedex

I posted it again so you can read it again dr z. I was speaking solely on modifying the exhaust side with cat and muffler. And you agreed with it. Obviously if your going to mod the exhaust side you should do the same for the intake side.Which most end up doing because performance suffers from just modding the exhaust. Plus having to remap the timing. So if you reread my original post you will see what i was talking about. I think alot of people think that just by plunking on some free flowing cat and muffler that they will get a jump in performance. They dont realize that there is alot more to it. If you disturb the balance on the exhaust side you have to make up for it on the intake side which is what you did. Not to mention timing.
Toyota spends millions on research and developement to get the optimum performance and FUEL EFFICIENCY out of the motor that comes from the factory. Its tuned as a package. (power, torque,fuel efficiency,emissions,noise level) You disturb one side, you have to disturb the other side to gain optimum results. Which was my point.

Dr. Zhivago

Hey Ranc,

Welcome to the forums!

Headers, intake and exhaust would probably net you around 15HP on that engine. Maybe a tad more, maybe a tad less. You would definitely gain torque too, which would be more useful. I'd go with that plan. You seem to have a good grasp on what you want to do.

Good luck and let us know how it turns out!
Dr. Z

Joe

Here's a site that might help some people get a little better perspective of what's all involved. http://www.ssheaders.com/header.htm

Bumpin' Yota

How do I advance the timing on my 3.slow? Since I have the FIPK and soon a hiflow cat with stock everything else, should I do it with my engine having 218400 miles? Right now Im running Cheveron 89 octane to keep from pinging....

GREAT link on the headers, VERY informative

Bumpin' Yota

Like Dr. Z said, welcome to the forum!

On the list of mods, I'd like to add do the ISR mod and perhaps the electric fan mod unless you get in LOTS of mud....then I'd scratch the electric fan mod.

Manual hubs up front I dont think would hurt anything either on power or mpg but would definately save wear and tear on the front end axles.

Ranc-0

Thanks for your replys. << Full o' Guinness

A few more questions.

What does using an electric fan do for power? I am assuming that since it is not run from a pulley you may get a few extra hp.
I never thought about this one before.

Does installing the FIPK do away with the intake silencer?
How does the deckplate mod compare to the FIPK. Spending a few hundred for this does not really concern me, as much as which is better for power/driveability.

Also I am wondering if replacing the entire exhaust system from header to tip might reap the best gains. This is assuming that I get a good tuned header, freeflow cat, and muffler with stock diameter tubing in between. This is with some kind of good intake upgrade, of course.

My goal is still the same, I would really like to add around 25 hp without too much risk of losing low end. Whether I spend 500 or 1500 is not much of a consequence. Also I do not care about fancy looking - I know that shiny new exhaust systems and fancy intakes look cool- this does not concern me. Hey, I was considering the S/C until I heard how hit and miss this thing can be!



Thanks,
Ranc....

CTB

I don't think the supercharger's are really hit or miss. Ya, true, Casey did not have good luck with the supercharger on this 4Cyl, but I don't think you will hear many, if any, complaints from the guys who put them on the 3.4's.

Granted, to run optimally, there needs to be a couple fuel delivery upgrades, but like I said, I don't think the increased performance outcomes are hit or miss.