Close Topic Options

So I got my first taste of changing my corolla's engine for a few more horsies. Granted I was being guided the whole way by the guy who brought me up; but hey, everyone starts somewhere.

Right then. So we removed four of these 90 degree twisting pipes from under the 4-throttle plate. from what I was told, the procedure would grant me slightly more high end power at the cost of lower rpm torque and more noise.
Well, the thing was already growly, so I figured why not?

It revs faster now; but predictably uphill for it becomes a little more annoying.

My question being; what exactly did I just do to the engine, and how is it doing what it's doing?
Forgive me if I come off as an ignoramus; but that's why I'm asking.

Pics and explain what this means: "It revs faster now; but predictably uphill for it becomes a little more annoying." as this sentence is unintelligible.

I think what he's trying to say is that he swapped out his intake manifold.

If that's the case, what you did is you changed the air passages between the throttle body and your intake ports. There's a buttload of science involved in those manifolds. I'll sum it up as well as I can, but car manufactures will spend gobs of money on properly tuned intakes, there's more to it than I can explain.

If you were told it would sacrifice low end torque for top end power, what you probably did was get a manifold with shorter yet larger diameter air channels. But why don't you have that as stock equipment if it's clearly better? Good question. The longer intake runners on the stocker are good for speeding up the intake charge through smaller passages, effectively cooling the charge air and helping fuel atomization. The problem is, it's slightly restrictive when you're on the upper ends of the rev range. The swap you did will allow it to breathe more easily at the top end.

Sounds more like removal of runners. Either way, pics are required or everything talked about is hearsay.

Amen to that.

Side note: This probably belongs in the technical section.

What you did was remove the factory intake runners that normally sit inside the factory intake manifold. You basically altered the air path into the motor. Id do a couple of things depending on what you do mostly with the car. For starters, id put those velocity stacks back on- Id prefer the down low where i am 99% of the time, if you ever want to take them off for whatever your racing needs may be, theyre 2 bolts each. Second, Id find a way to attach some kind of filters to them. I siliconed uni filters to the ends of each of mine- Sucking up unfiltered air into your motor is cool if its a race motor you plan to rebuild all the time, but sooner than later (within a couple years depending on your driving) youll lose compression on that motor and need to rebuild it.

For the record, ive had my set up on the dyno, with the factory stacks+filters on versus off (bare open itb, no stack, no nothing, just straight up butterfly), theres absolutely -no- difference below about 5k'ish rpms. From there the change is pretty sharp, with a peak total of 20 whp less with the stacks/filters. 115 with filters/ factory stacks, 135 without. Just some food for though. Seeing as 99% of my driving is well below 5.5k, i opt for the cleaner dirt and particle free air.

You're talking like he's got a blacktop. Silvertop's are MAF'ed, not MAP'ed, so a central source of air is needed, not four individual sources feeding the throttle-bodies. He wouldn't need filters on stacks because he wouldn't have stacks, all that'd be needed is a filter on the central source.

All of this is why I said that pics are needed to see what he did.

This post has been edited by flohtingPoint on Apr 29 2010, 01:25 PM

He removed the intake runners from inside the factory airbox/collector.

EDIT: And I love having a blacktop rather than a silvertop

EDIT: To the OP, I'd advise putting them back on as well. You probably won't gain very much up top if you're still running the factory intake piping and airbox/collector, and considering it's a silvertop you can't just run the throttles "open" as sideways mentions anyway...

This post has been edited by Mr. Shine on Apr 29 2010, 02:02 PM

Yes, I got that, I said he removed runners in my 2nd post.

Sideways was talking about tossing filters on stacks, which doesn't happen unless the motor is converted to MAP.

I want pictures to make that's all that was done.

Seemed pretty clear-cut to me, because obviously if he'd removed the rest of the intake the car would run like ass.

But of course you already know this.

This post has been edited by Mr. Shine on Apr 29 2010, 02:08 PM

Never underestimate a rookie with a wrench. I assume nothing when it comes to other folks work and expect the worst.

You could also be ultimately wasting your time if the person with the question doesn't have said vehicle/motor/part and is just dicking around.

This post has been edited by flohtingPoint on Apr 29 2010, 02:15 PM

Fair point. I'm pretty sure I've seen pictures from this poster of their car before though, but yes

Out of curiosity, what are you running in your Corolla?

I am moving the topic to the Technical section.

I'm through with 20v's. I have a 11.5:1 small port 16V.

I don't blame you in some ways. I've been keeping an eye out locally for a cheap 16v to build up for fun. Or had been, until my dad sold his light engineering workshop and therefore any chance of space to keep it...

Meh im totally happy with my 20v. About 1k not including the clutch and ive got a reliable 135 whp with a neato' ricer sound and i get 35 mpg.

As for the op, i was udner the impression from the simplicity of his post that it was map based versus the afms maf based, in which case my suggestions would matter for shit at all. Well have to find out what it is.

Man, you guys and your insane number of valves. I've only got 12. I'd gladly swap for a 24 valve BMW motor though, I can't name one bad one.

Hey my Z only has 12

Well, it'd be more "insane" if our engines were 6-cylinder. 24 valves is almost ordinary when you're dealing with 6 cylinders

I got 20 valves.....5cyl =p

pics should come in this weekend once i get access to a pc with net. i'm currently browing with a phone... So yeah.

By rev faster, i mean that the car became a little more responsive; enough for me to notice that the vvti kicks in a sec sooner. The car had crap for torque in the beginning though, so even less torque now means I have to drop it into third or second revving it higher than i'd like, without really going anywhere.

Yeah, the whole point of the removal was to eek out more power from the little thing. Technically I dont own it; it's a plaything of my dad's that stays and is used by me. My little learner track car and daily driver for college.

The only real work that had to be done was searching for bolts that fit the thread holes, since they were attatched. ive got em lying around in the basement as of now.

@shine
Running?

There is no chance you're getting to ~4400 a second faster, this would require a massive change in HP or gear ratio. If anything, you're sending dirty (not dirty as in unclean, dirty as in stirred up) air into your ports due to the added turbulence from the removal of the runners. The intake plenum isn't flow-benched with them out. Any exaggerated after effect you're feeling is psychosomatic.

Finding a second in a car is not as simple as this. If it was, then I'd need an FIA license to drive my Corolla with everything that's been done to it.

I still dont seem to understand. Without the pipes, isnt there less air being limited at higher rpms. And thus I get a quicker rev once that point is passed?
Lower engine speeds I think I get; the pipes help push air in by narrowing the path. But as the engine spins faster, wouldnt the above start to hold true?

My mistake. In hindsight, I probably should have left it at 'more responsive'. All Im sure of is that the car's quicker than it was after 3 months of driving it around.

The intake runners are designed to effectively guide and streamline the air flow into the throttle bodies, in much the same way as a well-designed intake manifold streamlines airflow into the cylinders past the more common single throttle body. As it stands, without them, regardless of engine RPM the air is not streamlined, and therefore does not enter the throttle bodies smoothly.

If you want to truly improve performance, you could try getting some aftermarket intake runners/trumpets to fit inside your factory airbox.


The car will not be quicker. What an ordinary driving experience makes you define as quick is a car's acceleration, which is more directly impacted on by the engine's torque characteristics than its power. You've lost torque, therefore it will accelerate slower. It's purely, as floh alluded to, a placebo effect. You're imagining it.

This post has been edited by Mr. Shine on Apr 30 2010, 08:36 AM