I've been running the 65mm throttle body on my focus for a couple of years now. At first it seemed to make the car more fun to drive and once i put the turbo on i never found out whether it allowed for better flow or not. The one problem i have with it is driveability. The car is a lot harder to drive "smooth" with the 65mm tb than with the stocker. I think someone here has tried going back and forth between them and found little difference (Rod?)...can you guys post on what's the best way to go?
Considering going back to oem throttle body
Petik
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I've been running the 65mm throttle body on my focus for a couple of years now. At first it seemed to make the car more fun to drive and once i put the turbo on i never found out whether it allowed for better flow or not. The one problem i have with it is driveability. The car is a lot harder to drive "smooth" with the 65mm tb than with the stocker. I think someone here has tried going back and forth between them and found little difference (Rod?)...can you guys post on what's the best way to go?
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I had issues of driveability when the TB plate would stick but ever since I got that resolved, I have no issues with the TB acceleration being 'jumpy.'
I switched back and forth several times between my stock and 65mm and the 65mm seemed to have more pep off the line than the stocker.
Also, I know for the JRSC, Oscar did a test between the stock and 65mm and found that it increased power.
You can see the resutls HERE.
.
I switched back and forth several times between my stock and 65mm and the 65mm seemed to have more pep off the line than the stocker.
Also, I know for the JRSC, Oscar did a test between the stock and 65mm and found that it increased power.
You can see the resutls HERE.
.
thanks for the input, i should have clarified more...
yes, i had the sticking plate issues, too, but the "jumpiness" is what bothers me - especially with my spec stg3 clutch you really have to match up the rpms right.
i was also looking for an input on a turbo, not supercharger application. these two would be very different from the point of view of using a throttle body since one has to suck air through it and the other one pushes air into it. i can see how a larger tb would help a roots style blower, but i'm not convinced either a centrifugal or a turbo would benefit...
yes, i had the sticking plate issues, too, but the "jumpiness" is what bothers me - especially with my spec stg3 clutch you really have to match up the rpms right.
i was also looking for an input on a turbo, not supercharger application. these two would be very different from the point of view of using a throttle body since one has to suck air through it and the other one pushes air into it. i can see how a larger tb would help a roots style blower, but i'm not convinced either a centrifugal or a turbo would benefit...
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I can't vouch for the FC, but I ditched my very nice BBK for driveability issues.
My theory is the little bit of air the turbo moves upwind of the throttle plate at idle is the reason that, at least in my case, I couldn't get a satisfactory idle. The ISC would be completely closed, with the throttle plate stop screw adjusted to allow the the plate to close as far as possible, but the idle was still too high.... but then I wasn't going to be satisfied to run a 1,100 or 1,200 idle or whatever in order to use an aftermarket part.
In any case, to have any hopes of perfect drivability after doing anything to the TB you must dial in the ISC transfer function. Also with injector and/or MAF changes that are essential with FI, the ISC idle air will also likely need to be retuned. Sidenote: I think this is one of the main reasons mail order tunes seem to routinely be flops - there is no way I can think of a guy could tune for these properly without the car.
My theory is the little bit of air the turbo moves upwind of the throttle plate at idle is the reason that, at least in my case, I couldn't get a satisfactory idle. The ISC would be completely closed, with the throttle plate stop screw adjusted to allow the the plate to close as far as possible, but the idle was still too high.... but then I wasn't going to be satisfied to run a 1,100 or 1,200 idle or whatever in order to use an aftermarket part.
In any case, to have any hopes of perfect drivability after doing anything to the TB you must dial in the ISC transfer function. Also with injector and/or MAF changes that are essential with FI, the ISC idle air will also likely need to be retuned. Sidenote: I think this is one of the main reasons mail order tunes seem to routinely be flops - there is no way I can think of a guy could tune for these properly without the car.
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That's what I did..Petik said:
I had idle issues too when I first installed my FC 65mm TB and I had to flip my TPS 180 degrees to resolve the idle issue.
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I have had nothing but good luck with my FC 65mm TB, drivability it better than stock.
Maybe its in the tune?? You know maybe too aggressive at tip in?
Maybe its in the tune?? You know maybe too aggressive at tip in?
Interesting observation. I just installed the OEM TB back in and went for a ride. I have to say, after driving with the 65mm TB for 2 years now, the change was at least as extreme as it was going up to the 65mm.
OEM
The car feels a lot less like a race car and a lot more like a daily driver again. At least half of the sweep of the gas pedal is very nice part throttle feeling where you practically don't get into boost, but if you really punch it, you still get full boost and I don't think I lost any power. This truly feels like no turbo car when you're just driving around, but like a monster when you hit it.
65mm
With the 65mm, I was in boost practically all the time and that made it a lot harder to rev match. Car "felt" faster, but was also harder to drive as a daily drive. I think my gas mileage suffered a lot because of this as well - time will tell.
OEM
The car feels a lot less like a race car and a lot more like a daily driver again. At least half of the sweep of the gas pedal is very nice part throttle feeling where you practically don't get into boost, but if you really punch it, you still get full boost and I don't think I lost any power. This truly feels like no turbo car when you're just driving around, but like a monster when you hit it.
65mm
With the 65mm, I was in boost practically all the time and that made it a lot harder to rev match. Car "felt" faster, but was also harder to drive as a daily drive. I think my gas mileage suffered a lot because of this as well - time will tell.
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That sounds about right. The second half of your gas pedal is now functional.
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Sorry to jack the thread, but how did you connect your 65mm TB to the airbox or are you using a SRI or CAI on the JRSC? I had the Steeda SRI and FC 65mm TB, but it won't fit after doing the JRSC.
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1,926 Posts
I had the Volant and used the JRSC supplied accordin upper tube to connect it.springbuck said:
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When I had my supercharged Focus, I had the FC 65 mm TB. I think if I were to do it again, I'd just do a ported stock TB.
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