ST184 headers/extractors...?

[Bahnugget]

as it's written up there ^^ the economy heads are built in such a way as to restrict the engines flow at high revs.. if the engines not geting as much air, it uses less fuel.. toyota was pretty smart when they did this.... as for modding it, it also says up there that cams and stuff arent really worth doing.. the 5S is a torquey car, its never going to be a high reving power machine, so extractors probably arent worth it unless you're looking for bling, or planning on altering the head..

[Nim]

Ha ha ha...people on here really do know what they're talking about huh...? =)

Some do, some don't.

Thanks for all that...

No probs. Click my rep thing if you found it helpfull. I want an avitar.

ummm...my next question was actually if extractors would be beneficial or not...now that I can assume they fit on the 5S-FE yeah...? Would they help with the 'lumpier' cams? (I'm not familiar with that terminology...does that mean higher lift or something...?) or would they just be a waste of time all together...?

Well this is what I'd like to know. Would extractors help at all? I don't know enough specificaly about the 5S-FE, and haven't modded one so can't say for sure. My GUESS would be that you'd actualy lose power, but it's just an educated guess, not fact.
As for lumpier cams, yes, it means they would have higher lift and duration. Although as said, the whole head is designed for low revs, so even if you overcome the lift and duration, then you have valve sized (which can be changed to an extent), and port shape and angle (which are impossible to change), and if you do put lumpy cams in, it might hit the piston and cause exploded engine.

Also, on a side note...so many people say it's such a waste of time modding the FE engines because of the 'economy' head...does any other manufacturer make engines this way...? I haven't heard anything like this for other engines, and I've heard of a fair few SOHC lancers and civics producing a decent amount of power...? I dunno...I just fully don't know much about all this, so if anyone could help...=)

I know the SR20DET engine is a CLOSE angle head. But close angle doesn't = bad, it just makes it harder to make a sports engine out of one due to the port angle, and valve size. A turbocharged engine isn't going to have as much trouble with flow in the head, as it's having air forced into it, rather than having to suck air in. So if you're talking about Turbo SOHC Lancer and Civics, then yeah, that'd be why. Once you start talking about turbos though, it comes down to boost and all gets a bit silly what with tuning and how long the engine will last, etc etc.

Anyway, the real issue is, to get the 5S-FE to be any good at all would cost FAR more than just dropping a 3S-GE in there, or even a 3S-GTE. and in the end, the 5S-FE isn't going to perform as well.

[RWDboy]

*sigh*

A Toyota economy head (or FE head) is a close angle head to provide a nicer combustion chamber shape (better compression and easier to get good squish areas), but has the downside of needing to up the angle that the ports enter the combustion chamber, which is fine for low RPM, but an issue for flow at high RPM. It also has the downside of not having nice spacing for cam gears and timing belts, usually requiring some kinda crazy cam gear design, or lash adjusters (ala the SR20DET).

Also, if I'm not mistaken, most 'FE' heads have smaller valves and port sizes than ‘GE’ heads, which is great for low end flow, but sucky once the revs get high. Oh, and the cams have smaller lift and duration, making for better low end torque, but worse high end. This can be fixed by lumpier cams, and larger ports + valves, but then you might have issues with the valve hitting the piston, so you might need new cut-outs (seen it happen on Honda engines with bigger VTEC lobes and a shaved block - BAM, right into the piston). Anyway, that means engine rebuild time. And a 3S-GE or 3S-GTE engine swap is a much better option.

So now everyone knows what an FE head is, can we answer my question?
Are the limitations of the flow in the head itself going to be improved at all by a better exhaust manifold? Will the power be made worse by putting extractors that are designed for higher revs on a low revving engine? I’ve heard that the exhaust manifold on a 4A-GE are good and don’t need replacing before you get lumpier cams, so why woulda 5S-FE need upgrading?

Unless the extractors are just for the sound. Then go for it, but before you do consider that you might actualy lose power, rather than gain any.

Okay - lets answer the question first.

Do Toyota design their extractors with tuned length and flow in mind? Yes - but they also have to consider packaging, manufacture, noise/vibration/harshness (hence the weight of the things) durability (hence the cast iron), emissions, heat management (what temperature do they want the gases to be at when they get near a catalytic convertor or a EGO etc?) and of course, heat dissipation.

So any set of Toyota headers are going to be a compromise.

If you fit extractors on, you will *probably* get a hp increase (however small) unless there is some kind of side effect that will effect your catalytic convertor, the radiator (remember the exhaust is right next to it) or the EGO.

Next thing let's dispel some 'myths' here.

The *reason* that port angle may, or may not, lead to a less powerful engine is because the combustion chamber roof is flatter. What does that mean? That the combustion chamber roof has less *area* .... the less *area* you have to play with, means the smaller your valve area must be. Ports that are at a smaller angle between intake and exhaust actually flow *very very* well, often because the path of the air can be made straighter and to follow less curves. This is what leads to 'economy' ... because the head design lends itself towards there being *less* restriction to air flow.

Of course, there is only so large a valve you can fit - but every engine on the planet suffers from this.

The squish area that you talk about is not entirely taken advantage of by the 5S-FE, they have a fairly straight-forward dish-type piston. Meaning there isn't much in the way of dynamic compression near the spark plug. Not saying that this is a bad design or anything, it's reliable - but it doesn't help to make power.

The 5S-FE is perfectly mod-able ... a decent set of extractors will help things just like they do on any other N.A. car.

There is also the fact that the valves move closer to 'perpendicular' to the combustion chamber roof, meaning the more lift you run, the closer the valve runs to the piston (as opposed to a wider angle valve set-up). So to make a 'free-running' engine requires greater clearance/relief between the piston crown and the combustion roof/valve.

So basically any modification will pretty much work the same as it does on any other engine. There is nothing that fundamentally special about a narrow-angle designed head that will suddenly invert the findings on other engines.

[Aust162]

As rwdboy said, the extractors should fit the 5sfe fine. Turbocharging the 5sfe in america is quite popular. they use the 3sgte manifold and it fits straight up to their 5s motors.

Well designed extractors should definately help any standard motor. you usually notice extractors help with mid range power and a bit up top.

[Nim]

RWDboy, from what I've read, the curve on the runners into the head make for the problems with flow, this is a result of the angle on the ports (or the pent roof) as there is only so much room under a bonnet. That, and port size, is why the sports model heads made by toyota are wide angle. That's fine for low revs, but as airflow increases, so does turbulance. Also, while the 5S may not have great squish areas, a flatter roof does make them easier to make (or so i've read).

I've heard of plenty of people chucking extractors on their cars and then making LESS power as the extractors weren't designed for the engine. Happens a LOT with Honda engines. If blah_00 is thinking of chucking extractors on that are designed for a 3S, I'd just caution to double check that they will actualy work with a 5S design at all. You seem to think they will make more power, I have my reservations about that.

Extractors can only be designed to flow best at a certain RPM. If the current manifold is designed for low to mid range, and you replace it with one thats designed for high end then you may lose all low and mid range, and the FE head may not have the flow up high to utelise the extractors, so they may esentialy do nothing except suck all your driveability. I've also heard stuff about problems with back pressure, but I don't really know much about that.

My advice? Ask someone who's dynoed their car before putting 3S extractors on their 5S, then dynoed it right after to see the difference. Don'y just trust what those of us who are 'theorising' say. That includes me. I might be wrong, 3S extractors might work brilliantly. But I doubt it.

Actualy my real advice would be to ditch the whole engine and get a gen 3 3S-GE.. actualy no, too much work... ditch the whole ST184 Celica, and get a ST182 imported from Japan (if you can... actualy I don't think you can, forget it) or buy a Honda Integra VTiR / Type R. Much better cars.

[RWDboy]

Sounds far more like they (the Honda owners) fitted a pair of crap extractors.

3S and 5S engines are similar enough in design that any pair of off-the-shelf extractors will work roughly the same on either engine (in terms of flow increase).

'Back-pressure' is a fallacy, don't buy into it.

If you want to fit a pair of longer, or straighter intake runners, then yes you will have trouble fitting them under the bonnet with the FE head - but that would be quite a serious modification - something that you would worry about *much* further down the line than thinking about fitting extractors.

Extractors designed for particular RPM are basically using harmonics to scavenge extra air out of the combustion chamber during the exhaust stroke. The factory headers aren't even equal length - the flow capability of them will be greatly reduced because of that, and also they are almost *definitely* causing a restriction in the exhaust at higher RPM that will prevent good scavenging of exhaust gases. If you think that a pair of higher flowing, (or furthermore equal length) extractors won't help, then you are off your nut.

Yes - sometimes you have to sacrifice some bottom end - which may reduce street driveability. It depends on where you want your peak torque to be, and over what rpm. If you are fitting extractors to your car, then you are saying that you expect to use higher rpm than a typical street daily application (where you might only go to 4000rpm to get up a hill). You have to use gears and drive to the torque spread of your car ... it's always been like that, always will.

[Nim]

Back pressure a myth huh? Would explain why nobody can really tell me what it is, or how it works.

But if you sacrefice some bottom end, what's to say that the top end flow that the 3S has is too high for the 5S... meaning the 5S never reaches the point that the extractors are designed for? Thusly losing power accross the board... Although even i'm thinking that's a bit of a stretch. *shrug* they can't be THAT much different, especialy as the 5S has more capacity.

Anyway, anyone done this and can tell us for sure?

[blah_00]

Thanks guys! I'm learning heaps from this! Just reading all the backward and forward theorising...=) just wondering though...how do I 'check' your rep thing? I wouldn't mind 'checking' both yours and RWDboy's...I just don't know how to do it...=)

[c2888]

page 156 of 21st century performance has some results of a exhaust upgrade on a 5sfe
no dyno graphs unfortunately

4-2-1 extractors and 2 inch cat, the rest stock, gain of 6%
the remaining replaced with 2 inch for a total gain of 11%

heaps of guys on mr2oc forums have 5sfe motors, because in usa they got turbo 3sgtes but NA 5sfes.

Another plus with extractors is loosing the massive lump of cast iron.

dan

[blah_00]

wow...one post between my posts...=) Also, I'd love to get a 3S-GE chucked into my car...or even a 3S-GTE...but I got this car JUST (6000kms?) after the previous had replaced the engine, and therefore don't wanna just waste an engine...? so I'm looking more at modding or possibly even turbo-ing the 5S if that's not too much of a waste of time and money...=)

Also would love to go for an mr2 or VTEC honda...but realistically I'd probably only be able to sell my car for what it's cost me just to get it to it's current shape...so yeah...=) that good enough explaination...? =) THanks again!

[RWDboy]

Well first gen 3S-GE and the 5S-FE put out the same kw - so they pretty much flow the same amount of air (stock), so i can't see why the 5S-FE wouldn't be able to take advantage of the extractors the same way a 3S-GE can.

Another thing you are forgetting is that any *decent* set of extractors will be designed with equal length for all primaries (if 4-1) and equal length secondaries (if 4-2-1). The *theory* is that you don't get two flows from different cylinders interfering with each other. The standard headers aren't equal length, and hence they cause more back pressure and flow less air than a set of extractors. Any time that you create more backpressure - you have to have less overlap (which can make tuning and cam-selection a pain), and you will have more exhaust gases and less fresh charge going into the cylinder. Also, the piston has to do more work in the exhaust stroke.

If the extractors are designed for 'mid-range' then that would relate more to the length/width being tuned for particular revs (and timing the pressure waves so that you get extra low pressure as the intake valve opens) - and not many off-the shelf extractors are that well designed - sorry to say. Running a bigger diameter pipe doesn't necessarily mean the engine will not perform at mid-low rpm.

In some cases the emissions gear will not perform perfectly, and that could lead to the engine de-tuning itself marginally at lower RPM. This is how adding extractors can reduce mid-range performance (compared to stock manifolds) - but it has nothing to do with the flow characteristics of the engine. I think most of these cars have some form of EGR system in order to introduce inert gas to the combustion chamber to absorb heat at the flame front (thus reducing NOx emission i think). But as with ANY modification you make, it's up to the ECU to take full advantage of it - which is why you *want* programmable or piggy-backable ECU's (unlike the ones found on most 3S-GEs and 5S-FEs)

Lastly extractors aren't a big lump of cast iron... they are usually made from tubular steel which is both strong and light - so if nothing else you can save yourself a coupla kilos. Only problem is that they don't damp vibrations as much as the cast manifold.

[Nim]

I like my Integra VTiR... although I kinda wish I'd bitten the bullet and gotten the Type R.

Apparently the 3S-GE in the ST182 121kw : http://english.auto.vl.ru/catalog/to...a/1991_8/5775/
*confused*

So yeah, the 5S-FE makes like, 96kw or so. Even the ST162 3S-GE makes 110kw.

[blah_00]

Sorry...I'm pretty sure that's wrong though...at least I know something...=) He he...umm...yeah...I think the Gen 2 3S-GE makes about 121kw...or 123kw? Something like that...but the 5S-FE makes I think quoted 100kw...and the gen 1 ST162 3S-GE makes...I think 103kw? So yeah...not heaps of difference at all..in terms of pure output that is...=)

[Nim]

Heh heh. Man, I'm so sick of power figures! Every freeking source I look at states different number! ARGH! lol. But you did just say the Gen 2 3S-GE has 121kw, which is exactly what I said. But I think you're right on the ST162, I think it's 103kw.

I have an idea, get your car dynoed, strap the new manifold on, test it again, then come back and tell us what you got!

Personaly though, I'd keep the ST184 stock, have your fun with it, then get something that's a better base for upgrade later. Like a DC2 Type R. Or ST185 GT-Four! Forget turbo FWD... ick... well that's what I think.