Nihilanthic

I didnt say they dont make torque, dumbass, I said they have a flat line of torque on a graph, meaning the power curve is accordingly peaky, as opposed to making a peak at midrange that tapers off giving a flat power curve.

Also, yeah, Ive slid geo metros around corners left foot braking like an idiot before. Ive even managed to do the same in an N-Body. But Im not an idiot who mistakes flat torque with no torque

I understand what VTEC does to the movement of the valves and why it does it quite well.

I also know that 2 valve heads dont drop like a rock north of 6500 rpms, youre the one who doesnt understand how everything works.

A lot of STREET CARS with 2 valve heads "drop like a rock" noth of 6500 rpms because its peaked its ability to flow air through those heads, given the displacement of the motor, and/or its out of the cams rpm band, and/or its out of the harmonic range of the intake. Those same heads with a 'wilder cam' and less displacement (such as a destroker crank) would be able to spin higher. Why? The displacement is lower and thus its demand for air is too.

There are "two valve headed" smaller displacement motors that can spin as high as you want and then some, and some four valve headed motors with some SHITTY head flow cant fall on their face at a 'low' rpm as well.

Um, I know pushrods dont have a damn thing to do with the torque curve unless they instigate valve float, or flex at higher rpms meaning it wont open at the right time, or not enough, which can definitely mess up the right side of the graph anyway - that comment was to the ignorant ricers who are fond of saying bullshit about pushrods.

So sorry youre so new to the whole game you didnt pick that up.

Also, the number of valves really doesnt matter all that much. its a matter of how much air you can move, and the ability of that head to flow as much as youre need to make the power you want.

It seems like you'd think a smaller displacment engine with something like VTEC so it made flat torque at all rpms and revs high is better than a bigger motor that doesnt rev as high, but makes the same power AND for a longer time with more torque.

Id rather have the displacement, higher torque, and more area under the power curve, thanks.

rarson

A flat torque curve is the very opposite of a peaky powerband. Obviously you've never driven a car with a flat torque curve. The engine's ability to *hold torque while revs increase* make the car feel as though it's accelerating just as fast. Remember that old saying, torque is what you feel? Yeah, well with a flat torque curve, the car feels just as fast accelerating from, say, 3000-4000 rpm as it does from 4000-5000 rpm.

Edit: That's actually one of the things I love about the RX-8: it pulls almost all the way to redline.

I'm sorry, I meant driving cars, not showing off or acting like a dumbass.

This statement very much proves that fact!

I'm talking about the basics of head design. You know, valve shrouding, airflow, and general fluid dynamics. The fact that the valve covers a much larger area while providing less room for airflow just might have an effect on airflow, no? 2-valve heads are great for flowing at lower rpms, 4-valve heads are better for flowing at high rpms. Even a simple 30-second stint with Desktop Dyno would clue you in to that.

Just because GM designs a good 2-valve head or Kia designs a crappy 4-valve head doesn't mean that they set the standards. Strictly speaking, what I stated about the head with regards to fluid flow is true, forget about the intake manifold.

I might also mention the fact that 2-valve heads require higher seat pressure, which puts more strain on the cam, which also increases the parasitic drivetrain loss, etc. All reasons that 4-valve heads are better suited to high rpms than 2-valve heads (I can't believe you're actually arguing this!).

So am I an ignorant ricer or were you just not talking to me? Before you answer that question, let me remind you that I stated: "There is nothing wrong with pushrods."

LOL... what, new to the benchracing game? Sorry, homey don't play that.

Sure, but the number of valves WILL have an effect on the engines ability to make power in low or high rev ranges, which is what I said before. Man, this is getting tiring!

So now you're telling me what I think? DAMN! EVERYONE, BOW DOWN TO THE ALL-KNOWING NIHILBENCHRACER! HE KNOWS ALL! HE WILL READ YOUR MIND!

That's nice, but I never asked you what you'd rather have because frankly I don't care.

digitalsolo

iTrader: (2)

I'm sure you're considering the fact that while the 2 valve heads have a higher seat pressure per spring, the 4 valve heads have 2x as many springs, which equates to a higher gross total spring pressure. I'm sure you're also considering parastic drag on 2-4 cams vs. a single cam, and the associated chain routing and tensioning losses.

While 4 valve heads do have definite advantage in some areas, they are far from an end all.

jimlab

WOW, it must.

Good for you.

Sadly, I haven't had that pleasure... nor have I wanted to.

Nope, never have.



Maybe he couldn't drive that well, no matter how capable the car he was in happened to be. It happens.

That would probably depend largely on who was driving it, wouldn't it?

It's called clarification for the benefit of others. If you hadn't noticed, this thread is full of ignorant people who aren't likely to reach the proper conclusion when you make an open-ended statement like "gearing makes up for torque".

No, horsepower is a measure of the application of torque over time. I thought even the slow ones had finally achieved enlightenment on that subject a few pages ago.

Force moves the car, not "power". F = ma, remember? Refresh my memory on how to calculate force, if you would be so kind...

Uh... if you'd actually said it, I wouldn't have to finish your statements for you.

Torque-wise, yes. Gearing-wise, no.

Funny, because gearing has a direct impact on how the car drives.

If you hadn't noticed, I don't care. Preserving the feelings of some punk from Guam who thinks he's hot **** because he drove an RX-8 once isn't high on my list of priorities, unfortunately.

Ditto, tough guy.

wrxracer55

iTrader: (3)

Lol

Orr89rocz

dont necessarily need shorter stroked motors to rev. any motor will rev as long as its built for it. my friends 496 chevy stroker big block revs to 7600rpms and makes upwards of 750hp n/a or so. he has your standard pushrod motor with 2 valves per cylinder. but teh cam is designed to make power up in that rpm range, and the intake and heads are designed to feed the air requirements for that rpm range and power.
but agreed, most street V8's never seen north of 6000rpms. they dont need to as they can make plenty of power under 6k rpms. my 383 plans should make near 500hp n/a at 5800rpms. LOL

[quote]If you hadn't noticed, this thread is full of ignorant people who aren't likely to reach the proper conclusion when you make an open-ended statement like "gearing makes up for torque".[quote]

with higher rpm peak torques, your not gonna have alot of bottomend torque so you need more gear to help get the motor to spin into its power band. cars with abit less torque than other similar motors need more gear to run as fast. case in point... 305 TPI motor made about the same hp (around 230) as the 350 TPI... although actually difference might be more like 10-15hp. but the torque was difference by about 30-40lb feet. the 305 car with the 5 speed and 3.45-3.70 gears would run nearly the same as the 350 car with the auto trans and 3.27 gear even tho the 305 was down on torque and about the same hp. both cars are near the same weight too. the gearing differences helped alot to make it more even. if that 350 had the 5 speed and 3.45s, it would rape the 305 bad

GtoRx7

iTrader: (5)

Ah, the joy of a P.O.S. microtech computer, it was glitching badly under 2800rpms, and I didnt want it to start ******* with the engine, as pre-ignition was occuring. So yeah, I started the pull at 3000rpms, if I had done it from idle it would have been a nuch better example, but keep in mind this is 3x55mm throttles, and dont have a ton of down low velocity. So does it have no area under the curve? Dont compare it to a 5.7 liter's torque, mine is still a 3.9 liter, remember that.

GtoRx7

iTrader: (5)

Seeing as how my n/a 3-rotor can only get so much torque to a degree, (which is about 220rwtq) I made a new dyno plot making my same engine lossing its torque (or negative jerk, as Nihil has said). Is this ficitional version of my engine faster? According to Nilhilantic it would be a better engine? Because how you explain it, makes it sound like you think so. But I sorta think you dont right?

rarson

Jim, I'm not going to argue with you anymore. We're clearly in agreement on the core of the subject. No sense in debasing each other over semantics.

I thought that was pretty obvious...

Nihilanthic

No, you're wrong.


Flat torque, peaky power band.


Downslope of torque, broad plateau of a power band.

Also, Im sure that in theory a 4v should be better for high revving high power builds, but guess what? In PRACTICE, in PRACTICAL TERMS, the tuning: the displacement to max airflow of that head ratio, and how the port size relates to the airflow, the cam intake and exhausts rpm bands, decide that.

There are plenty of 4 and 5v heads that are in low rpm motors. Toyotas 1UZ would be an example. Lots of the VW/Audi 5v TDIs come to mind (well, any head on a diesel can only go so high...).

Now, for high rpm 2v heads? Uh, that ford 2.3 comes to mind in ported form, or getting the ARCA head from esslinger engineering... Im sure you know about canted valve heads and the HEMIEH!!!!111one, right? Tons of road racing and dragracing v8 heads live over 4500 rpms and suck below it.

Basically, you made a false generality. I just felt like pointing that out.

Nihilanthic

Youre making less total power and torque. We said from the beginning that 300 hp from a high revving, smaller displacement NA engine isnt as good as 300 hp from a lower revving, higher displacement, highre torque NA engine becuase the latter engine makes it for a longer period of its rev range.

Your example is making less total power completely. If you wanted to see what we meant, youd bump up torque in the mid and low end and have it taper off so it didnt make more than you made in the first place with the 20b, but have a longer duration where it made that power.

The point is the duration (with rpms as the 'time') in which it makes that power. We're saying a long powerband is better than a peaky one. See the VTEC vs v8 examples - and yes I realize the v8 is making more, but the point I was trying to point out is the shape of the POWER Curve.

The v8 has a longer powerband period than the honda. If the honda made the same peak power as that v8 but with the same shape on its power curve, it wouldnt be as fast.

rarson

Yes, I understand what the computation of a flat torque curve looks like when plotted in a graph of horsepower. I think what you fail to realize is what exactly that powerband feels like. If torque is constant, the powerband DOES NOT feel "peaky."

Right, and as torque drops off, so does acceleration. When people talk about "peaky" powerbands, they're talking about dyno queen Supras, for instance, whose powerband is way high up in the rev band, sudden, and short-lasting.

All of which can be altered when building the engine. But you'd still get better results matching the head configuration to the powerband your looking for. Also, I can't help but be confused by what you've stated: "the displacement to max airflow of that head ratio?" "How the port size relates to the airflow?" What the hell are you talking about?

Head porting is all about flow vs. velocity. You port too much, you lose velocity, and no matter how much "flow" you gain (on the bench), you lose power. I don't know what "ratios" and "relations" you're talking about but I've never heard a head porter say those things.

WHAT??? Stop talking about stuff you have no clue about. First of all, the 1UZ is in no way a low rpm motor. It's got an 82.5mm stroke, 149mm rods, 6-bolt mains, and heads that will flow well into 7000 rpm. Secondly, I don't know a whole lot about VW's, but could you enlighten me as to which TDI's had 5 valves per cylinder? Because my research tells me none of them do.

Once again, the discussion is here while you are off in la-la land. I never said a 2-valve engine couldn't rev, or wouldn't make good power up top. I said that 4-valve engines are better suited to that. You can talk all day about aftermarket this and that, but it still doesn't change that. Besides, the Ford 2.3 is getting pretty long in the tooth. There are a lot of better engines to start out with than the 2.3.

What does the Hemi have to do with this? All of Dodge's engines for the past umpteen decades have had hemispherical combustion chambers, that is quite irrelevant.

No actually, I didn't. And if you had been paying attention, you'd notice Orr89rocz already agreed with me. You are the only one arguing this point.

rarson

Sorry, does not compute. Rpm != time. There's a vast difference between airflow in grams per rev, and airflow in grams per second.

Nihilanthic

Did you miss the "'s, genius? I was using an analogy.

Nihilanthic

No, it doesnt feel peaky, but the POWER BAND is the POWER, not torque, POWER, band of the engine. We dont say "torque band", now do we? A BROAD power band will have inverse jerk (acceleration that dies off) becuase if you have a motor that has constant power at all rpms and no transmission the acceleration will be an asymptotic curve as wheel speed goes up. Peaky power can feel 'flat' becuase the torque curve is flat and thus acceleration is flat, but it wont achieve peak power for very long. A v8 that can make constant power for a long time, or a turbo motor that can make constant power for a long time, wont have flat torque - it cant have flat torque and have flat power at the same time.

People say ITRs have peaky powerbands as well but their torque is nebraska flat except for the VTEC surge (cos it kicked in, yo!)


So, you agree that the # of valves doesnt have nearly as much to do with the rpmg range it operates at as the tuning of the system?


Thats what I was talking about regarding airflow demand (displacement x rpms) in a given rpm range vs port size so you dont end up having too little velocity. Thats why you dont have giant ports on a motor that will only hit 5K rpms unless it simply has THAT much displacement. Theres that whole ratio thing again....


Why not go check if Audi has 5v TDI's with the magic of Google?

As far as the 1UZ having strong internals, short stroke, long rods, blah blah blah, all the DYNOS of them I've seen has flat torque from early on and then it starts to taper off around 6-6.5K. Maybe the newer xUZ motors can spin higher, but not the 1UZ dyno graphs I've seen... STOCK, at least.

Now, obviously, you can modify them to your hearts content, but that doesn't have anything to do with my point that its not an exceptionally high revving motor just because it has 4v heads. Its a luxo car motor made for streetability, emissions, MPG, etc. Also, the headflow of a stock 1UZ is nothing to write home about... check the 1UZ info thread in "other swaps"

How is a 4v head better suited if it can be tuned for torque, and a 2V can be designed from the get-go for high flow?

And regarding a starting motor.. its cheap, simple, been around a long time, abundant, and strong. What more would I want?

Hemi heads are canted valve 2V heads that can support insane headflow. It was just a reference to a high flow high rpm 2v head design.

sudseh

...not having to read sillyness about how much power someone got on what superduperported engine with such and such and so-on and so-forth... but it seems even on the 'other engines' side of things, a few people feel the need to verbally **********. oh well...

rarson

I checked numerous sources, including Google. The only 5V engines I could find were gasoline engines. Tell me where these mythical diesels exist please.

Other than that, you are hopeless. There's obviously no use trying to reason with someone who cannot grasp the simple concept of logic.

capn

I hear that lets quit while were ahead; close this thread!

88IntegraLS

Less talk more fabrication, some of you guys really need to get your hands on a project before you go crazy.

sudseh

88: doesn't matter in the slightest... there was this 7.4 liter lamborghini block I was going to put into my hyabusa, but one of my friends said it wouldn't fit so i got an rx7 instead. *nod*

rarson

I actually do have a project right now! My FC has been sitting in the garage for over a year now. I haven't yet finished building the MS-II yet, but I should be done by the end of this week (depends on how much time I get to work on it after work this week).

Originally, I was going to rebuild the S4 N/A motor and turbo it, but I'm really liking the idea of a swap. Only problem is, I already have a ton of rotary parts for it, including the HKS manifold and a GT40 turbo. The A/R is too large to run on just about anything besides an LS1, I'm sure. I think I'll just stick it out and swap if and when the engine lets go later on. It's not a daily driver so it's not a big deal.

Orr89rocz

theres a few really high horsepower STI's running turbos like that, and some decently powered single turbo Grand nationals. thats a big turbo tho lol. LS1 could take it tho.

rarson

Heh... yeah, I was thinking that, but the problem is, I really don't like the idea a whole lot of crossing over and joining two banks for one turbo... but then again, I guess it's not that big a deal. It's divided, so I guess I could run the banks separately.