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The best part about me is that I think I am better
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rod,
if you are coming up for the dyno day, we can try it out when you are on the rollers. we'll do your car as one of the last ones that way i can pull the TB and stick on aftermarket unit and you can see with your own eyes what it does.

if you like it, buy it, if you don't we'll stick the stocker back on!
 

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Discussion Starter #7
rod,
if you are coming up for the dyno day, we can try it out when you are on the rollers. we'll do your car as one of the last ones that way i can pull the TB and stick on aftermarket unit and you can see with your own eyes what it does.

if you like it, buy it, if you don't we'll stick the stocker back on!
Damn Mitch, that is quite an offer, thanks. I don't know if I will make the dyno day or not, it is too far out to know yet.

Thanks to you too for the offer Randy. I couldn't ask you to go out of your way like that, but it would be pretty interesting to see back to back tests on something in the 200 - 250 WHP range if the opportunity presented itself.

I think a turbo application would be particularly interesting as since the air travels through so much small tubing when travelling from the compressor to the TB, it is hard to see how there could be much gain there.... but you never know as that tubing flares up to meet the TB inlet and then is necked down again withing the TB.... so who knows?

Troy I look forward to hearing how yours turns out.
 

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Rod, I'd expect there are some substantial gains possible once you get well up over the 200hp mark. The stock TB is pretty nasty looking as you know.

However, much more importantly, the new TB *MUST* be properly designed, and I haven't yet seen one that was (though I haven't looked in years).

If the opening isn't very progressive, your trottle will be like a light switch, and you'd be slower on anything other than a dragstrip.

With a responsive turbo, it MUST have a very progressive opening. This can be done with a huge snail shaped cam, which I haven't seen anybody do yet.
 

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Driver > Car
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23,988 Posts
I saw 0 gains on both my zx3 and svt with the vortech setup.
throttle response is better (especially in the zx3, barely noticable in the SVT).
 

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What a [censored] waste of time! Now I remeber why I hate all the damn TBs out there.
Vik was even grinding away on this cus one of the pieces was machined wrong. Awesome.

Zero gain , TP isn't on the money anymore causing me to have to dial in the MAF table all over again, and [censored] idle and I get to drive around like this for a day. I can't believe some people like these on the Zetec.


Save your money.
 

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1,109 Posts
this is a biased opinion, you hated it to start with. the only way to know rod is to try one. Worst case you turn around and sell it. On the FI cars i have delt with you notice a huge differance in throttle responce over OEM(ported). In my mind on a NA focus the OEM TB is turbo lag, and the 65mm is instant responce. That what it feels like to me.
 

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The best part about me is that I think I am better
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4,481 Posts
deamon,
that's interesting becase we gained 5fwhp and 6lb/ft from a TB on a JRSC'ed SVT.

think about it this way...
if you look at race cars, many are limited by a restrictor to keep the power-weight ratio similar between cars. obviously this has an effect on power or they would not require such things.

P51,
i'm not sure about the light switch comment... with my powerworks kit i have found my FC TB to be very easy to modulate, granted this is not a turbo but i am not having issues.

Rod,
either way the offer is there.
come up on the 6th and we can put this issue to rest once and for all! we'll strap your car down, do a couple of baselines, pull off the stocker and stick on an aftermarket TB and do a couple more pulls. it will either show gains or it wont but atleast we will all have an answer one way or another.

Scott,
I still got it, send me the money and i'll send you the TB!
 

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420 Posts
If it makes a diffrence in power or not, I cant say...
But I like the improved throttle response. Matching revs is alot easier, all it takes is a small blip of the throttle.
Rod you have driven my car with the TB installed havent you?

One thing I have found, (and this could be a by product of a not so good tune im running right now) is that you have to ease into the throttle a little slower than with a stock TB. If the throttle is slammed open, it tends to bog. But with a more progressive roll on of the thottle, rather than slamming it open I dont have a problem. Once again im not sure if this is because of a crappy tune, but I imagine It would still do it with a good tune. I just seems like too much air is introduced into the system to quickly. This is just my observation though.

Rod, next time im up at sarahs parents (should be soon), I can stop by for the day and you can try mine if you like? Its a easy install.

Might help in your decision making.
 

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Driver > Car
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with the JRSC there will be a difference because the throttle body will serve as the largest restriction in the system given the compressor is after the throttle plate.

with all other forms of FI you're not limited by the TB but by the actual diameter of the intake ports in the manifold and head itself. what gain is there if the TB is larger than the intake manifold ports? you only have one piston drawing air at a time, correct?

anyway, the aftermarket TB's are more blingtastic, and i got in on a group buy, so i got one.

maybe it makes more of a difference with turbo'd or non-FI cars, i dont know.

also of note: the TB did not affect my MAFS counts for the tune. at least not much IIRC.
 

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Not Special Enough
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10,540 Posts
what difference could a TB make in power? none. 7psi in the manifold is 7psi regardless of throttle body size. as long as the TB isnt SO small that its limiting boost (and for that matter vacuum) power will not suffer.
 

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Its not just how much psi you make.

Its volumetric flow...
you could have say 30CFM of flow at 7 psi,
OR with bigger ports or TB you could get say 35cfm at 7psi.

DISCLAIMER:These numbers are just for reference, they may not reflect actual numbers that you engine makes


So a TB could make a difference
 

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Not Special Enough
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if you can sustain pressure, what difference can the TB make? Its not a flow issue.
 

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I can definitely see it making a difference on something like a blower that is *sucking on* the throttle body. But on a turbo or centrifical blower that is pushing on it, the air is compressed already, and needs less of an opening.

The problem with a bog when whacking it open, is your "transient fuel correction". I can't remember what it's referred to in the stock ECU or the flashers. Might be "trimpot"?

When you whack the throttle open, the ECU squirts some extra fuel in, similar to "dashpot" on carbs. With a larger TB, the calculation is off, and so you need to increase that fuel enrichment.
 

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Flow IS an issue,
On my SVT when we changed intake manifolds the car picked up about 20whp at the same psi. Since psi didn't increase and IF flow makes no difference where did the extra power come from?? Also this was with out changing the tune.
 
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