# Converting to drive by wire. What throttle size?



## Egnaro (Jul 27, 2014)

My 32 currently has a single 100mm throttle (endless plenum) and I'm converting to a Link ecu and want to go drive by wire. I'm wanting a more progressive throttle so what would you recommend? 
Also what is the max power/flow on
A, Bosch 82mm, B, 90mm and C 102mm throttles?


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## ben_harmer32 (Feb 16, 2012)

Just out of interest, what are the benefits of drive by wire?


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## Egnaro (Jul 27, 2014)

ben_harmer32 said:


> Just out of interest, what are the benefits of drive by wire?


Better driveability, emissions, response and fuel economy


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## mambastu (Feb 13, 2002)

and Anti-lag, throttle blipping on gear changes, non-linear throttle calibration.


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## joshuaho96 (Jul 14, 2016)

Drive by wire allows you to delete the IACV, all idle control can be controlled by the throttle body, improves reliability and makes for a more compact intake system. You can also do traction control more easily. As others have mentioned you can also have automatic rev matching on downshifts/upshifts and a non-linear throttle curve (artificially increase throttle to spool the turbos and then close it back down to avoid a big torque surge) to achieve a linear acceleration on the pedal. You can also do stuff like cruise control for free, just some software in the ECU to implement a feedback controller. Implementing anti-lag mechanisms is also easy, just ignore the accelerator input during gear changes and keep the engine running at some minimum level with highly retarded timing to spool the turbos, the ECU can also turn this feature off dynamically if it detects that you're not in a situation where anti-lag is needed. BMW does this in their current turbo cars, if you aren't in sport/sport plus mode and keeping the engine in high load/rpm situations then anti-lag automatically shuts off.

Electronic throttle body also means improved control of things like fuel injection. The ECU can basically limit how fast the throttle opens/closes to ensure that the mixture remains consistent and therefore emissions control works properly and you don't get rich/lean spikes. It's harder to nail transient fueling in engines where the ECU is basically at the mercy of the driver and it can't know 100% for sure what's really going in the cylinders.


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## truupR (May 30, 2016)

mini thread revive.

I've never even considered a drive-by-wire setup but I was watching haltech heroes video on a 1100bhp street R32 which drove smooth as butter on the street. Admittedly it uses an auto box, but the drive-by-wire _*sounds*_ like it'd transform the drive-ability to another level. Is this the case?

I'm running a Link currently - how much would all this guff cost to get up and running? not even mildly clued up on what I'd need parts-wise


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## Egnaro (Jul 27, 2014)

I'm using an LS 102mm throttle and modified the flange on my endless plenum. Total cost (excluding mapping) just over £600.


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## Egnaro (Jul 27, 2014)

Forgot to mention I'm using a corvette pedal bought s/h from a US salvage yard


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## joshuaho96 (Jul 14, 2016)

truupR said:


> mini thread revive.
> 
> I've never even considered a drive-by-wire setup but I was watching haltech heroes video on a 1100bhp street R32 which drove smooth as butter on the street. Admittedly it uses an auto box, but the drive-by-wire _*sounds*_ like it'd transform the drive-ability to another level. Is this the case?
> 
> I'm running a Link currently - how much would all this guff cost to get up and running? not even mildly clued up on what I'd need parts-wise


What kinds of drivability issues are you running into? Keep in mind that drive by wire is just an actuator, your ECU needs the logic/software to actually make anything of it. At the most basic level it's not much to talk about compared to a conventional cable throttle body. It's only if the ECU supports more sophisticated features that it really becomes interesting.


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## truupR (May 30, 2016)

joshuaho96 said:


> What kinds of drivability issues are you running into? Keep in mind that drive by wire is just an actuator, your ECU needs the logic/software to actually make anything of it. At the most basic level it's not much to talk about compared to a conventional cable throttle body. It's only if the ECU supports more sophisticated features that it really becomes interesting.


Not having any issues at all to be honest - it just seems like something that'd be beneficial to have assuming it isn't going to cost a few grand to get all up and going. I've never really looked into it, but heard it talked about in the past. Some of the features sound really awesome. 

Would I be right in thinking the Link G4 supports DBW?


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## Egnaro (Jul 27, 2014)

joshuaho96 said:


> truupR said:
> 
> 
> > mini thread revive.
> ...


I bought a G4+ extreme ecu to go dbw as the 100mm cable throttle was fierce and having driven a similar spec 2.8 dbw to mine the difference in driveability was incredible. Perfect idle and auto blip are also what I want.


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## bladerider (Jun 29, 2002)

Yes G4 Extreme and Fury have DBW specific inputs for TB and TP


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## joshuaho96 (Jul 14, 2016)

Egnaro said:


> I bought a G4+ extreme ecu to go dbw as the 100mm cable throttle was fierce and having driven a similar spec 2.8 dbw to mine the difference in driveability was incredible. Perfect idle and auto blip are also what I want.


Makes sense. Link makes mention of an anti-lag function related to DBW. I assume you can force the throttle open and either inject fuel with highly retarded timing or just keep it WOT with fuel cut off to slow down the rate with which the turbo spools down this way as well.

It would be interesting to know if there's some kind of torque management feature in these ECUs where they attempt to linearize the response of the engine i.e. initially going WOT on throttle tip-in to get the turbos spooled then dial back the throttle as the car approaches the acceleration target commanded by the pedal.


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## Simonh (May 24, 2002)

throttle size is generally driven by power requirements - IIRC when I last looked at it a 70mm TB was good for around 700bhp, 80mm over 900 I think.

The bigger the TB plate the less progressive the throttle is so depending on your desired application you may want to go with the smallest TB for your desired power goal possible.

for drag you want to go big obviously


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## Simonh (May 24, 2002)

High Performance Math

High Performance Math

a couple of useful links on the subject


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## joshuaho96 (Jul 14, 2016)

Simonh said:


> throttle size is generally driven by power requirements - IIRC when I last looked at it a 70mm TB was good for around 700bhp, 80mm over 900 I think.
> 
> The bigger the TB plate the less progressive the throttle is so depending on your desired application you may want to go with the smallest TB for your desired power goal possible.
> 
> for drag you want to go big obviously


Is it possible to linearize the behavior of the throttle body somewhat? Something that would start off with relatively large cable pulls to crack the throttle body open and then progressively require less cable. DBW would make this simple, just change the pedal vs throttle curve.


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## Simonh (May 24, 2002)

It is an interesting proposition, not one I have thought about tbh


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## Egnaro (Jul 27, 2014)

joshuaho96 said:


> Simonh said:
> 
> 
> > throttle size is generally driven by power requirements - IIRC when I last looked at it a 70mm TB was good for around 700bhp, 80mm over 900 I think.
> ...


I was advised to stick with a 100mm dbw (102mm actually) as my concerns about wanting to lose the fierce cable throttled 100mm can be removed by mapping strategies. I've driven a 2.8/to4z/280 cammed dbw coverted (cheers Clive) 32 and it was a different league to mine. Stock quality idle, lovely progressive throttle, auto blip, full throttle changes etc.
Can't wait to get mine mapped in November.


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## GTRNICK (Apr 29, 2005)

Egnaro said:


> I was advised to stick with a 100mm dbw (102mm actually) as my concerns about wanting to lose the fierce cable throttled 100mm can be removed by mapping strategies. I've driven a 2.8/to4z/280 cammed dbw coverted (cheers Clive) 32 and it was a different league to mine. Stock quality idle, lovely progressive throttle, auto blip, full throttle changes etc.
> Can't wait to get mine mapped in November.


If I end up building my billet engine I will be going this route myself. It’s the way forward.


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## tarmac terror (Jul 16, 2003)

DBW has been on my spec list for quite some time now. As said above it offers a whole range of cool features. My intention is to use it alongside a paddle-shift converted sequential box which should be a great package...


TT


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## bladerider (Jun 29, 2002)

joshuaho96 said:


> Is it possible to linearize the behavior of the throttle body somewhat? Something that would start off with relatively large cable pulls to crack the throttle body open and then progressively require less cable. DBW would make this simple, just change the pedal vs throttle curve.


Yes

You can buy eccentric throttle cable guides - I have one on my SR20 by GKtech


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## bladerider (Jun 29, 2002)

Yep

DBW throttle mapping is awesome and will become the standard.

My RS4 is like two different cars with the friendly map in regular mode using first 30% travel for only 10% throttle opening its lovely and easy to drive in traffic etc.

Switch to sports mode and linear throttle and youd swear it was a different (fairly horrible) car !! lol

The 2JZ will have a couple of different maps I can switch between depending on what its being used for - drift/track - and the requirements of the course etc or you can just plug in and dial up throttle as required if necessary.

J.


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