When is BIG too BIG?

spinwax · Jan 22, 2002

I have mentioned this in other TB threads, but my question has usually been passed over. I dont really know a ton about the air intake needs of a 2.0litre Zetec engine. A alot of people on here have been putting on the Focus Central 65mm throttle body on their cars (I believe its 65mm). This just seems too big to me. Please explain to me why I am wrong or right. I have owned a ton of late model Mustangs as most people on the JET may know. I have put TBs on all of them. My last Mustang was pushing 480RWHP and I only had a 70mm Accufab TB on it. This was more than enough. I know this because I tried both a 75mm Accufab and an 80mm BBK (just for fun) and dynoed the car. I lost not only low end but a few Hp at the top as well with these larger throttle bodies, which was a supprise to me.

Most people believe in the MORE AIR IS BETTER thought.

Im having trouble believing that the Focus engine can really utilize a 65mm TB when Most late model Mustangs are happy and actually run stronger with 65mm up to 350 or so RWHP. Does the design of the Zetec, ect, need this size?? Im sure companies like Focus Central have done some testing and homework. I know that the addition of the TB does add some HP to the Focus, but would a cleaner designed, smaller TB do the same or even better?

People are claiming better throttle response etc, but I think that is just due to the better design, stiffer throttle spring etc and $250.00+ price tag LOL!!!!!!. How about keeping the unit the same size as stock or a few mm larger but with a better design, IE, billet or machined alum, with clean, smooth walls, flow design etc.

Just curious what everyone has to say.

2001 ZTS · Jan 22, 2002

I'll take on the question since it seems quiet here. Believe me I'm no expert though!

How about the air requirement of a 5.0L V8 at say 3000 RPM is about the same as a 2.0L four banger at say 6000RPM. Relevent at all?

spinwax · Jan 22, 2002

<blockquote>quote:<hr>Originally posted by 2001 ZTS:
I'll take on the question since it seems quiet here. Believe me I'm no expert though!

How about the air requirement of a 5.0L V8 at say 3000 RPM is about the same as a 2.0L four banger at say 6000RPM. Relevent at all?<hr></blockquote>

Well right off the bat, a Zetec needs low end more than high end power IMHO. Usually putting on a LARGE TB will kill some low end torque. That is the last thing one would want to do on a little 2.0liter engine. 4.6-5.0 etc have tons of low end, so loosing a little is actually not that big of a deal, especially for road racing, slalom, etc.

When are you running a Zetec at 6000RPM all the time. I would want more power in the RPM Bands that I would normally be in. 99.9% of the driving done with the Focus's on here is on the street. So wouldnt the average person on here want better STREET performance. I think that a 65mm throttle body would only help in RACING applications.

speedy_zx3 · Jan 22, 2002

you are right, but then how many people do you know that shift at 3k rpm in a focus?

protocol706 · Jan 22, 2002

why not bore your stock throttle body for better throttle response...

EazyErikN · Jan 22, 2002

I have the 65mm TB, and I want to buy a 62mm size or something close to that if it ever becomes available. I personally agree with you. It is a little too big, but not really by a whole lot. The negatives of the 65mm unit however, do not outweigh the positives of it.

Jays2000ZX3 · Jan 22, 2002

I think it's cuz a lot of people, when they mod their Focus, it's not for street driving, it's to get the MAX HP, or the BEST 1/4 mile time. So you have to sacrifice a little of street drivability to achieve this.

For me, low end torque, I could not care less since when I will be at the track, I am never below 4000rpm anyways. Except in 1st gear, but with more torque down low, you need to be able to effeciently put it to the ground.

It just depends on what you want I guess.

02InfraZX · Jan 22, 2002

Yeah I don't understand bigger is better theroy either. I know very little about these engines but I do remember reading that the MAF sensor is in a tube that cannot be changed (the dia) because it samples a set amount of air/fuel to control the mixture, so I would think this piece (the MAF tube) would negate the advantages of a larger TB due to its restrictions, unless you replaced it with a Pro Flow Mass Air kit and a custom burned chip, with larger injectors and better cams.

spinwax · Jan 22, 2002

<blockquote>quote:<hr>Originally posted by Jays2000ZX3:
I think it's cuz a lot of people, when they mod their Focus, it's not for street driving, it's to get the MAX HP, or the BEST 1/4 mile time. So you have to sacrifice a little of street drivability to achieve this.

For me, low end torque, I could not care less since when I will be at the track, I am never below 4000rpm anyways. Except in 1st gear, but with more torque down low, you need to be able to effeciently put it to the ground.

It just depends on what you want I guess.<hr></blockquote>

I personally dont think there is more than one or two people on the JET who have enough done to their engine to utilize a 65mm TB. I dont think that a CAI, exhaust and UDP really is considered a lot of engine work. Even with cam swap I think that 65mm is too large. I would like to see the power gains of slightly larger than stock and a ported stock. I think people on here would be pleasantly supprised at the gains.

No one has hard facts that the throttle body makes much of a dif, except for 1-3Hp. Unless I missed it somwhere, and someone can show me. For 250 bucks there has got to be a better way. I would love to see the HP #s on a Tricked out stock TB.

For putting the power down to the ground, there is plenty of good front drag radials that will help with that problem. If you can make the power there will always be a way to put it to the ground.

JJ'sGreyS2 · Jan 22, 2002

This is an interesting topic, but what is the size of the stock TB?

spinwax · Jan 22, 2002

<blockquote>quote:<hr>Originally posted by JJ'sGreyS2:
This is an interesting topic, but what is the size of the stock TB?

<hr></blockquote>

Im not sure.. I think around 53? or somthing like that.

FriendlyFocus · Jan 22, 2002

#1 It's basically the only aftermarket TB around

#2 It makes a huge difference in the way the car drives

#3 Nice and shiny blue

I have absolutely no idea whether it gave or took away any hp or torque at all. But it sure makes the car respond and drive worlds better. That's about it.

SOON2BN-FOCUS · Jan 22, 2002

I thought it gave them better throttle response and pick up. I was considering gitting it. I need alot of pick up for my auto, I got turbo lag with out the turbo.

---Herb---

BLOWNSTANG · Jan 22, 2002

I run a 65mm TB(with 12psi of boost)on my mustang. We have guesstimated 580 crank hp(129mph @3050lbs). To make that hp on motor it would need a larger TB(75 or 80?). A 65mm on a focus seems too big to just throw on a stock motor. If you have your head and intake ported w/larger cams then hell-yah get a bigger TB. 60mm should even be large enough(stock 5.0s' make 225hp with a 60mm)but since they don't make it yet a 65mm will have to do. The stock TB is probably even just fine for forced induction(correct me if anyone has dyno #'s showing gains w/65mm).

teamDFL · Jan 22, 2002

There is an equation that can tell you how big a t/b you need for a given hp level on a naturally aspirated motor. Since hp is a function of airflow, it is not that hard. Difficuly part is the laminar flow part of the equation as that has to do with the whole surface area to volume ratio, squared versus cubed thing.

spinwax · Jan 22, 2002

<blockquote>quote:<hr>Originally posted by BLOWNSTANG:
I run a 65mm TB(with 12psi of boost)on my mustang. We have guesstimated 580 crank hp(129mph @3050lbs). To make that hp on motor it would need a larger TB(75 or 80?). A 65mm on a focus seems too big to just throw on a stock motor. If you have your head and intake ported w/larger cams then hell-yah get a bigger TB. 60mm should even be large enough(stock 5.0s' make 225hp with a 60mm)but since they don't make it yet a 65mm will have to do. The stock TB is probably even just fine for forced induction(correct me if anyone has dyno #'s showing gains w/65mm).<hr></blockquote>

I agree, it tells you somthing when you can make 5-600 in a mustang with a 65mm, you just dont need that on a Focus.

What do you have done to your MUstang? Sounds like you have similar HP to my old car. I had a 347 Coast High Performance stroker, running only 10psi out of a Vortech. It dynoed right at 479 at the wheels with around 515torque. I could have made more power, but wanted a reliable street/open track car..LOL.

[ 01-22-2002: Message edited by: socalfoci ]

BLOWNSTANG · Jan 22, 2002

I'm the one that e-mailed you regarding the C&L meter(still testing). It has a 308(stock crank & rods)w/ported TFS T/W heads, stock lower intake w/box upper and 12psi Vortech. It was built for drag racing and occasional street use. Focaljet needs a magazine that's called "Fast Foci and Muscle Mustangs". E-mail me if you want to talk more(Moderators probably don't like off Focus topics in this forum

).

CasperSE+ · Jan 22, 2002

We measured mine at a shop the other day, the stock throttle body is right at 55mm.

L8r

BJ

spinwax · Jan 22, 2002

Well I think 10mm larger is a big step up. Im really supprised that FC would jump up that much. I would like to hear their reasoning on such a large jump. When TBs came out for mustangs, the first few yrs you could only get 65mm.

<blockquote>quote:<hr>Originally posted by BLOWNSTANG:
I'm the one that e-mailed you regarding the C&L meter(still testing). It has a 308(stock crank & rods)w/ported TFS T/W heads, stock lower intake w/box upper and 12psi Vortech. It was built for drag racing and occasional street use. Focaljet needs a magazine that's called "Fast Foci and Muscle Mustangs". E-mail me if you want to talk more(Moderators probably don't like off Focus topics in this forum

).<hr></blockquote>

Oh yeah,,,sorry I forgot.. I totally remember now. Im actually looking at buying an 89lx coupe right now. Not sure if I can swing it money wise unless I get rid of my current car.

[ 01-22-2002: Message edited by: socalfoci ]

YellowZX3 · Jan 23, 2002

<blockquote>quote:<hr>Originally posted by speedy_zx3:
you are right, but then how many people do you know that shift at 3k rpm in a focus?<hr></blockquote>

I do!! Get 35 mpg, too!

If the aftermarket made a 60mm throttle body, I'd be in heaven. The only reason I haven't gotten the 65mm one is because I think it is too big for a relatively stock motor. But if all the mags are getting all-around improvements, can the larger one really be that bad?

When is BIG too BIG?

spinwax

2001 ZTS

spinwax

speedy_zx3

protocol706

EazyErikN

Jays2000ZX3

02InfraZX

spinwax

JJ'sGreyS2

spinwax

FriendlyFocus

SOON2BN-FOCUS

BLOWNSTANG

teamDFL

spinwax

BLOWNSTANG

CasperSE+

spinwax

YellowZX3

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