75mm throtle body too big for a custom 2 piece?

[speedfreek500]

I got a 75mm tb from a 2005 f150 5.4L.I did a ford warranty motor swap and keep the TB from the engine.Its a drive by wire but i removed the motor from it and can weld a throttle cam from a stock on to it easy.It has a 4 wire tps,iam i could figure out the wires as need'd to make it work.Back to my concern would it be too big for a custom upper plenum on a lower two piece? 2.5 swap g-head and holset in a glh omni auto.


Thanks for the replys

[rbryant]

I got a 75mm tb from a 2005 f150 5.4L.I did a ford warranty motor swap and keep the TB from the engine.Its a drive by wire but i removed the motor from it and can weld a throttle cam from a stock on to it easy.It has a 4 wire tps,iam i could figure out the wires as need'd to make it work.Back to my concern would it be too big for a custom upper plenum on a lower two piece? 2.5 swap g-head and holset in a glh omni auto.


Thanks for the replys

Yes, 75mm is too big. It is actually too big for even a DOHC 2.4 or 2.5 turbo engine. If you were an NA engine then MAYBE it would help but the turbo cars just don't need it and it hurts fuel economy with no power gains.

Your tip in throttle control will be bad making the power very peaky and the car will be harder to drive without any power gains.

Stick to 60mm or less until you are at 400hp or more.

Most likely 52mm is your best match but if you want to go bigger you can go up to a 58mm 3.8l caravan TB and both of them are bolt on.

The 60mm Jeep 4.0l TB also has a 60mm plate but a 56mm taper on the inlet for better tip in control and uses the same style connectors as our cars.. It can be opened up to 60mm but I doubt it helps much.

The 5.0l mustang also came with a 60mm TB with no taper. I have one of the 60mm Mustang TBs that I can sell you cheap if you want it but the jeep unit is nicer.

There are also lots of larger aftermarket mustang TBs. If you want to mess around with different sizes to see how much it helps or hurts I would setup my intake manifold for the mustang style TB. That way you can do back to back dyno runs with just a quick 5 minute change of TB if you want to go try it and document your results for all of us.

Beware though that ford uses a PWM AIS motor instead of a stepper so you won't have AIS idle control.

-Rich

[speedfreek500]

Thanks for the reply,i guess i will turn into a elec exhaust dump as that was my first thought when i looked at lol.I dont need to waste my time on a tb that wont work for my car's new intake.I'll use a 52 or 58mm.

[puppet]

I got a 75mm tb from a 2005 f150 5.4L.I did a ford warranty motor swap and keep the TB from the engine.Its a drive by wire but i removed the motor from it and can weld a throttle cam from a stock on to it easy.It has a 4 wire tps,iam i could figure out the wires as need'd to make it work.Back to my concern would it be too big for a custom upper plenum on a lower two piece? 2.5 swap g-head and holset in a glh omni auto.


Thanks for the replys

Depends on what you're doing with the car ... drag only? If so, it should be just fine. If not, it becomes a question of fuel curve tuning ... the throttle transients. I've heard it said to run the biggest tb/carb you can correctly tune for if you're after the most power.

[GLHNSLHT2]

the 58mm on my big plenum 2 piece on a 2.5 gave the car instant throttle response. I wouldn't want to go any bigger.

[thedon809]

Seems other people run a lot bigger throttle bodies than us. Hell, my stock sohc neon has a 52mm tb. Most neon guys run 60mm tb's n/a or turbo. All has to work together though.

[shadow88]

Also, there's no advantage power wise to have a throttle body larger than your charge piping.

[turbovanman²]

Seems other people run a lot bigger throttle bodies than us. Hell, my stock sohc neon has a 52mm tb. Most neon guys run 60mm tb's n/a or turbo. All has to work together though.

Yeah, the one Honda thread that Ondonti linked us to, is running a huge one, and its an n/a 2.3, IIRC, he's up to 80mm.

Also, there's no advantage power wise to have a throttle body larger than your charge piping.

I would have to disagree here as the t/b has a throttle blade, which is a restriction. My 2 cent's.

[Juggy]

ive been looking into TB's 2day actually. ive decided to go with a jeep TB. they have 60 mm on them, and for a cheap price can be taken out to 62-63mm with a nice new thin brass blade.

I would not go bigger then a 70mm TB. myself, i am shooting for something in the 65mm range. try to help keep them part throttle tables sane lol

[RoadWarrior222]

I'll have to look into how those DBW TBs work, would be interesting to figure out how to drive them as an electrical slave off a mechanical actuated master in a dual TB setup.

[speedfreek500]

I'll have to look into how those DBW TBs work, would be interesting to figure out how to drive them as an electrical slave off a mechanical actuated master in a dual TB setup.

Try p12v power to one terminal,ground the other and use a rotary switch from the pedal to increase the singal wire ground,all DBW TB's are slower than a cable control so keep that in mmind also too.

[rbryant]

ive been looking into TB's 2day actually. ive decided to go with a jeep TB. they have 60 mm on them, and for a cheap price can be taken out to 62-63mm with a nice new thin brass blade.

I would not go bigger then a 70mm TB. myself, i am shooting for something in the 65mm range. try to help keep them part throttle tables sane lol

I also went with a Jeep TB because it is much nicer than the Mustang TBs and easier to adapt... I have a strange version from a '06 wrangler though that has a PWM idle valve instead of the stepper motor so there are less wires and complication in Megasquirt.



I actually like the fact that it tapers down to 56-57mm. If you watch the blade open slowly you can see that the taper actually makes the opening much more gradual for better throttle control.

I have a spare '96 cherokee TB if you need one.

Nissan SR20/KA24 TBs are also 60mm. Nissan TBs have a water line on them that we don't want but it can be plugged or drilled into the TB to be an air line.

-Rich

[Juggy]

yep it necks down to 55mm rich. the place im getting mine done from increases the plate size to 62mm and bores it straight thru!

http://cgi.ebay.com/ebaymotors/ws/eB...#ht_627wt_1165

id take you up on your spare TB as a core, but i already contacted the seller and they can supply me one for $45 which is $15-25 cheaper then the other places doing it, and they only charge 59 instead of 89!! so unless i could score one cheaper then $20 im not really going to make out much after shipping it around...

so $120 shipped pretty much, for a reman Jeep TB that will bolt on using my existing sensors and should be enuff to support 6-700hp.

i also checked out the nissan ones as well. yeah they r 60-65mm and those guys seem to go with the Q45 (i think thats what its called) throttle body, its 90mm lol..........all this stuff coinsides with the ross racing stuff, but in the end I decided to stick with mopar

[BadAssPerformance]

Yes, 75mm is too big. It is actually too big for even a DOHC 2.4 or 2.5 turbo engine. If you were an NA engine then MAYBE it would help but the turbo cars just don't need it and it hurts fuel economy with no power gains.

So if you had a 2.4L with 3" I/C piping, you would neck it down to what size TB?

Depends on what you're doing with the car ... drag only? If so, it should be just fine. If not, it becomes a question of fuel curve tuning ... the throttle transients. I've heard it said to run the biggest tb/carb you can correctly tune for if you're after the most power.

Correct on the part throttle tuning needing some attention.

The 75mm I run seems to do great in all driving situations, even when the 35R is not spooled. Now I could see someone who drive binarily (cannot modulate the throttle) having issues...

Also, there's no advantage power wise to have a throttle body larger than your charge piping.

I would have to disagree here as the t/b has a throttle blade, which is a restriction. My 2 cent's.

Yes the blade gets in the way to some extent, but thats only at WOT where that would matter right? Or if you have a 4" TB on 2.5" pipe, WOT airflow would be at ~60% throttle? BTW, I think Jamie means bigger differences, like no need for a 75mm when you have I/C 2" pipe...

[shadow88]

So if you had a 2.4L with 3" I/C piping, you would neck it down to what size TB?



Correct on the part throttle tuning needing some attention.

The 75mm I run seems to do great in all driving situations, even when the 35R is not spooled. Now I could see someone who drive binarily (cannot modulate the throttle) having issues...





Yes the blade gets in the way to some extent, but thats only at WOT where that would matter right? Or if you have a 4" TB on 2.5" pipe, WOT airflow would be at ~60% throttle? BTW, I think Jamie means bigger differences, like no need for a 75mm when you have I/C 2" pipe...

Yes, I meant a significant difference in tb size to charge pipe size. My car picked up 2.5 mph changing the charge pipe size from around 2" to 2.5" id .....With that, I feel I'm making better use of my 58mm throttle body.

[turbovanman²]

Yes the blade gets in the way to some extent, but thats only at WOT where that would matter right? Or if you have a 4" TB on 2.5" pipe, WOT airflow would be at ~60% throttle? BTW, I think Jamie means bigger differences, like no need for a 75mm when you have I/C 2" pipe...

True but its still a restriction and that goes without saying, 75mm with 2" piping is kinda dumb, , lol.

Yes, I meant a significant difference in tb size to charge pipe size. My car picked up 2.5 mph changing the charge pipe size from around 2" to 2.5" id .....With that, I feel I'm making better use of my 58mm throttle body.

2.5 mph, now was that repeatable or ? Interesting.

[shadow88]

Yes it was. On every good run, the mph was from 2-2.5 mph faster than before.

[rbryant]

So if you had a 2.4L with 3" I/C piping, you would neck it down to what size TB?

Well no, but I wouldn't run the 75mm with a 3" IC pipe on an 8v engine anyway....

I think the TB should generally be just slightly larger than the IC pipe to account for the blade.

I am not sure that a 3" IC Pipe is really worthwile on a street car but perhaps it would be after everything else was upgraded first.

-Rich

[BadAssPerformance]

Well no, but I wouldn't run the 75mm with a 3" IC pipe on an 8v engine anyway....

I think the TB should generally be just slightly larger than the IC pipe to account for the blade.

I am not sure that a 3" IC Pipe is really worthwile on a street car but perhaps it would be after everything else was upgraded first.

-Rich

If one has enough 8V thent he 3" IC and pipe is needed

Why not on a street car? Well obviously not a stock one but there are high HP street cars too...

[puppet]

^ I agree. At some point it comes down to removing restrictions on both sides of the engine so VE gets better. Every point in pressure differential measured across the intake circuit costs some HP. Can't get around that.