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I've been reading up on all the Drive by Wire threads but it seems a lot of information is spread out between different threads and I'm still left with questions. I'm not looking for info on the benefit of DBW (Drive by Wire) but I'm more so looking for information on all the parts that are needed and to answer questions that I'm still confused on as someone who is still learning. I'm building this setup for my Single turbo 500hp 13b-rew. (LINK BELOW FOR BENEFITS OF DBW)
Parts needed:
- FFE GM throttle body adapter
- GM DBW Throttle Body (The biggest confusion I had with this is finding which size I needed to go with for a 500hp single turbo setup. I couldn't find much information so I settled on a 90mm throttle body which I personally think is overkill but had trouble finding a smaller one. I remember reading a thread where TeamRX8 stated single turbo RX8s making 500hp were running really well with the 70mm throttle body. Does anyone happen to have a part number for a throttle body or link to one that's compatible with the FFE GM Throttle body adapter?)
- RX8 Pedal/Adapter (I found the RX8 accelerator pedal assembly to be around $80-$120. Where can i find an adapter to mount an Rx8 pedal to a RHD Fd? or does this need to be custom made?)
-I also found the option from Zprecision of a custom adapter they make to run a 5th Gen Camaro pedal with their custom adapter.
-(Please correct me if anything needs to be added to the list/removed)
Questions/Concerns:
-I have a greedy intake elbow. How would I adapt that to the throttle body? or must I get a completely different intake elbow?
-Converting to the DBW setup, do you essentially delete the throttle butterfly valves on the intake manifold?
-I read a thread someone suggesting to run a S54 throttle actuator to keep the existing butterfly intake manifold? Has anyone ran this? Would love to hear their input.
Will be ordering all the parts after I get some input from members and updating this thread once I'm able to test it.
Some of what I've learned. I ended up with a newer 90mm GM tb and Z-precision pedal adapter with GM pedal.
The other obvious thing needed is an ECU that supports dbw. If concerned about size, you could use an Rx8 dbw tb, JDL Mfg makes an adapter for it. When I measured the OEM tb, I came up with combined area equivalent to about 83 or 84 mm. Another thing needed is the wiring connectors, if using the GM stuff you can find mating connectors easily on Racespec Online for the tb and pedal.
Another option you mention but gets more costly is using a remote dbw motor such as from S54 with the OEM throttle body (see HP Academy project Rx7 did it this way). Even used, those BMW motors are pricey compared to a new GM or Rx8 tb then you have to deal with mounting and making the linkage.
The double throttle butterflies in the upper intake could be left in and used to direct air to the primary only at low load. Only seen one person on here doing this and car is not running yet. I've left my double throttle butterflies in, still trying to decide if want to remove or keep. By the nature of the arrangement, you lose some response with the big single blade tb's but it's never been quantified to my knowledge.
With the single plate tb's your Greedy elbow wont' work, you either use a coupling, weld a wiggins style clamp to it, or find a bolt on adapter that converts to wiggins clamp (JDL Mfg has this for Rx8 but I don't know of one for the newer GM tb's).
For an Rx8 pedal adapter, I think JDL Mfg might have one. Otherwise, I think Elite makes one.
I did forget to mention I'm running an Elite 2500 which supports DBW. I know you said the numbers don't exist, but I would be very interested in seeing the response lost due to the big single blade, I'm assuming it effects drivability at low RPMs. The s54 throttle actuator seems a lot more pricey which is pushing me towards the GM throttle body setup. Think I might go FFE adapter and new 90mm GM throttle body. I will be looking into the the JLD MFG or Elite Rx8 pedal adapter and wiggins clamp. Thank you Jack for the information.
I'm running the LS-A 90mm throttle body on an FFE-style adaptor, and the Z-Precision mount with Camaro pedal. The LS-A throttle body is much more compact than the other 90mm throttle bodies, there's lots of clearance for the oil fill. FT550 ECU.
The problem with the FFE adaptor is the manifold itself. You end up with big square bits of metal in the flow path. I cut out the middle vertical part, and I need to grind down the horizontal part for a nice smooth transition.
My application is a bit different, so I can't speak to the pedal adapter, but what I had conceptualized doing when the time comes (ergo not any time soon) was utilizing a bosch 82mm throttle body. They don't seem to be too expensive, and I believe JDL manufacturing offers an adapter that is to be affixed to the upper intake manifold.
I personally wouldn't bother trying to get the GReddy elbow to work with a GM throttle body (unless there is a solution that allows you to keep it as is, then disregard my previous statement), as you'd more than likely need to do some fabrication, and at that point you may run into the issue of having to go through so much trouble to get it to work (fabrication and development time) only to end with a finished product that might not work as well. You could likely have a fabricator make something for you that is designed for what you are trying to do and it might even cost less.
I think forum member @Pete_89T2 may have some experience with the large single plate with respect to dialing in drivability with an electronic throttle. I think it's somewhere in his build thread.
I think forum member @Pete_89T2 may have some experience with the large single plate with respect to dialing in drivability with an electronic throttle. I think it's somewhere in his build thread.
Yup, but a key factor in tuning driveability with a DBW throttle is the aftermarket ECU you're using - some offer better DBW based idle controls than others. I'm running a Link G4+, which has a very good ignition based closed loop idle control in addition to the usual DBW throttle based closed loop idle control. The ignition based idle control loop varies timing in the idle RPM ranges; if your idle drops below target, it advances timing or if it's too high, it retards timing. The benefit is the engine's idle responds & corrects itself much faster to ignition timing changes than it does to variations in throttle position. Long way of saying plan on letting your ECU's ignition based closed loop idle control do the majority of the idle control work, and use its DBW based closed loop idle controls handle the rest (i.e., higher idle during warmup, bump ups for extra loads like the A/C and so on)
To the OP's questions:
Questions/Concerns:
-I have a greedy intake elbow. How would I adapt that to the throttle body? or must I get a completely different intake elbow?
I just have a silicone elbow that adapts from the 4" DBW inlet on my GM 90mm LS3 DBW unit to my 2-3/4" intake piping. Not the prettiest thing, but it works.
-Converting to the DBW setup, do you essentially delete the throttle butterfly valves on the intake manifold?
-I read a thread someone suggesting to run a S54 throttle actuator to keep the existing butterfly intake manifold? Has anyone ran this? Would love to hear their input.
Wouldn't know about the butterfly valves in the intake mani question, as I got my FD from its PO with a Cosmo 13B-RE upper & lower intake manifold. Which essentially avoids the problem of staged air delivery with the REW manifold with a large single plate throttle, since the Cosmo mani is just an open plenum manifold which is better suited for a large single plate TB
I looked more into the adapter from Dorito and ended up ordering that over the FFE and will be ordering the 82mm Bosch throttle body. I like the smaller size and less space consumption in the engine bay. Thank you for the links.
After your explanation I'm probably going to ask my fabricator to make something for me instead of using the greddy elbow. It seems like a lot of extra work to make the greddy elbow work.
If I understand (Please correct me as I'm still learning these concepts) The closed loop ignition based idle is based off the open loop map. So if the open loop is off your closed loop will over compensate by too much which is bad. I'm not sure how good the DBW based idle is on a Haltech elite 2500 but I'm assuming if my base map for idle is good the closed loop won't have to over compensate drastically. So my question here, is something like cold startup tuned into the open loop and the closed loop just adjusts depending on how cold it is or do you just make a base map for DBW idle for the open loop and then the closed loop helps during cold startup?
Just started thinking about this; what systems can be completely removed/blocked off when switching to DBW?
Last edited by spintowinrx7; 05-02-23 at 09:04 PM.
You can remove the idle control valve /ICV that’s on the upper intake manifold next to the firewall, the double throttle, and of course all the throttle body bits. I think that’s it, not a lot to be removed
I'm about to start my DBW project with a Motec M150. I was leaning towards the Dorito adapter and Bosch throttle but the adapter is out of stock and has been for awhile. Wound up going with the latest FFE designed adapter, LSA throttle body, Z-Precision mount with Camaro pedal. Pretty much what @mr2peak did.
Was hoping someone that has done this before could verify the wiring diagram I was going to use. Particularly the petal pinout. I've seen a few different pinouts for this connector and nothing specifically identifying the 5th gen camaro petal.
10379038 - CADILLAC CTS 2004-2015
A APP 2 Low Reference E38 X102 Pin 7 E67 C1-37
B APP 2 Signal E38 X102 Pin 5 E67 C1-49
C APP 2 5 Volt E38 X102 Pin 6 E67 C1-35
D APP 1 Low Reference E38 X102 Pin 4 E67 C1-36
E APP 1 Signal E38 X102 Pin 2 E67 C1-47
F APP 1 5 Volt E38 X102 E67 C1-33
Figured I would share my DBW experiences here as it might help someone out in the future. I am by no means a professional tuner, just a hobbyist who has been tinkering with these cars for a while and has taken a bunch of HPA courses.
This is not on an FD so I do not post in this section much, but seems appropriate. The car is a FB with a S5 T2 engine swap. I wanted to give DBW a try back in 2019/2020 so I got a Franklin Performance S5 LIM to FD UIM adaptor and use the FFE GM TB adaptor to install a 90mm LS TB (jesus that’s a lot of acronyms). This is all being controlled by a Haltech Elite 2500 and a Subaru Throttle pedal that I made a custom bracket to mount to the car.
The FD UIM I got didn’t have the secondary butterflies (or anything attached to it for that matter) so I plugged all unused ports up, and installed it without any issue. Only a bit of fab work to clear the oil filler (this might just be an FC engine issue) and a oddly large silicone elbow to connect to my existing intercooler piping. To my surprise it started and idled with very little tuning in the scheme of things. Cold start, hot start and idle is all very good with DBW.
HOWEVER (and this seems to be most peoples complaint, at least for a street car), I was not happy at all with low/light throttle response – it seemed no matter what I did with the map, it was just getting too much air, at too low of a velocity (which is why the stock throttle body has the small primary port – to keep the velocity high) and caused the car to buck and stumble. The car was most certainly still drivable as I put several thousand miles on this setup trying to get it “right”, but it was still annoying. I tried making adjustments to just about everything I could think of – pedal to TB mapping, transient fueling, the main VE table to try to “fudge” it, but the stumble never really went away.
I eventually thought maybe the GM 90mm TB is just too big for my setup so I got a Rx8 throttle body (70mm roughly) and installed it on my FC UIM using a JDL adaptor. Again, startup and idle was pretty easy to get dialed in, but the stumble still persisted. Tired of playing around with everything I went back to the FC cable throttle body and have basically not looked back. It is super responsive, smooth to drive at all RPM’s and load points and just generally feels “right”. It also proved (to myself) that I actually know enough about tuning to at least make a functional car lol.
Sorry this post got longer than I expected - Again, not a pro tuner what so ever, just my experience. I suspect I will get the bug to try this again so I am curious to see what everyone else here is doing for tuning/setup as I can’t wrap my head around what you would do in the software to mimic the characteristics of the stock TB setup with it’s staged butterflies.
I'm still working out the tune on my 13B-REW FB, but I have the FFE adapter and GM 88mm throttle body (GM Genuine #12679524). RX-8 throttle pedal, and my UIM is completely stripped - no double throttle/etc.
I'm using the Elite 2500 and DBW settings from Skeese's map share. This has actually been one of the least problematic areas for me. Car idles great and seems smooth as butter! I did have to play with the enrich rate a bit to fatten up the lean stumble, but it was a relatively smooth process. Guess I got lucky.
Mazda had a drive by wire throttle on the Rx-8 but had shutter valves to close the secondary port runners. The mechanical throttles opened the secondaries when the throttle linkage moved enough.
now don’t you think if Mazda could have saved a buck they would have? Staging secondary ports was there for a reason, on street cars. I’m not saying DBW is bad, just know what you’re getting into. It depends on setup too.
I'm about to start my DBW project with a Motec M150. I was leaning towards the Dorito adapter and Bosch throttle but the adapter is out of stock and has been for awhile. Wound up going with the latest FFE designed adapter, LSA throttle body, Z-Precision mount with Camaro pedal. Pretty much what @mr2peak did.
Was hoping someone that has done this before could verify the wiring diagram I was going to use. Particularly the petal pinout. I've seen a few different pinouts for this connector and nothing specifically identifying the 5th gen camaro petal.
10379038 - CADILLAC CTS 2004-2015
A APP 2 Low Reference E38 X102 Pin 7 E67 C1-37
B APP 2 Signal E38 X102 Pin 5 E67 C1-49
C APP 2 5 Volt E38 X102 Pin 6 E67 C1-35
D APP 1 Low Reference E38 X102 Pin 4 E67 C1-36
E APP 1 Signal E38 X102 Pin 2 E67 C1-47
F APP 1 5 Volt E38 X102 E67 C1-33
Anyone have any insight on if the pinout information above is correct? Especially looking to confirm the pedal pinout.
I tried a ton of different wiring options until I got it to work. There's a bunch of diagrams out there, wish I could be more helpful. I don't remember what worked in the end.
Surely you're not advocating for putting an RX8 throttle body on a car making twice the power of a Renesis?
LSA throttle body is from an OEM application that makes ~560 crank, in a supercharged engine. Chevy could have used any throttle body they wanted, no matter the "rating".
BMW used a 77mm throttle body on the N54. That's rated at 330hp crank, twin turbos. 330hpx1.5=495hp. 77mm throttle body = 4656mm area. 4656x1.5=6964 = 94mm throttle body. So according to BMW engineers, 90mm is too small for our 500hp crank goals, it should be about 94mm.
LS1 OEM throttle body is 75mm, for 305-345hp. 345x1.5=517. 75mm throttle body = 4417mm area. 4417x1.5= 6625mm area, ~91mm throttle body for 517hp. Once again, just about the same ratio.
Please drop more throttle body size comparisons, I'm interested to see what else we find.
OEM 90mm LSA throttle body is rated at ~1,100CFM, the aftermarket and ported 90mm ones flow more. There's a bit of a curve on the back of the throttle body just past the throttle plate that gives finer control over the amount of air going past at idle and just-off-idle throttle positions. That might be why it flows a bit less than other 90mm throttle bodies, and that might be why Chevy was able to fit "such a large" throttle body on the stock LSA without sacrificing idle and drivability. I also have a progressive throttle curve I use, all DBW ECUs should allow throttle / pedal mapping. I could see a 90mm mechanical throttle body maybe giving you issues here? Perhaps there's some lag or response I'm giving up? Turbosource is trialing a few throttle body sizes on their new intake manifold, that might yield actual results. I'm guessing if it's tested properly, it will mirror OEM results, because science.
Yes, plenty of people make power on smaller throttle bodies. Would they make more on a larger throttle body? Probably.
FFE and LSA throttle body is an affordable choice comparing new parts. Nobody is wasting money with a 90mm setup with medium single power goals. The Dorito Design 82mm setup was twice the cost. If you have free parts from an rx8 you want to use, have at it I guess, but it's weird you'd advocate that as a better choice.
Yes I am, again there are RX8s with REW turbo engines making 550+ whp without issue using the RX8 TB and adapter on the REW UIM. Including the one I own.
Clearly you didn’t understand how TBs are even rated. If a TB flows 1,000 cfm at 28” vacuum, what do you think it flows with 1+ Bar boost pressure on it? You likely have much larger losses in your system than a 70mm TB would create at 600 whp. Which you likely don’t even have.
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Here's the thing: you had a 70mm throttle body on your RX8. It was free. It works for you. I'm happy for you bro, enjoy it. But that doesn't mean it's efficient or in any way the better choice for most people.
But, let's compare for fun because this is a forum lmao, and it wouldn't be complete without at least a little bench racing!
Closest I can find to your claims in OEM condition is a 997 turbo making 493hp with a 76.5mm throttle body.
Your 600whp FD, at 15% drivetrain loss, call it 690 crank hp, is at ~5.6 square mm/hp. And then multiply by 0.7 for "rotary hp" airflow requirements, it becomes 3.9 square mm/hp.
Throttle Body Area Comparisons:
690hp rotary (600whp) 70mm rx8 throttle body, (5.6 uncorrected) 3.9 square mm/hp
517hp rotary (450whp) 90mm throttle body, (12.3 uncorrected) 8.6 square mm/hp
997t@493 is ~9.3 square mm/hp.
LSA @580 is ~10.7 suare mm/hp
345hp LS1 is ~12.8 square mm/hp
N54@330 is ~14 square mm/hp
That's a pretty serious waffle stomp vs OEM sizing.
Those engineers have Billions in R&D backing, fluid dynamics degrees, etc and they seem to think those sizes are appropriate. Seems a bit obtuse of you to declare that work obsolete, no?
Let's take this one step further because it's fun and I feel like I'm learning!
Your throttle plate is ~2mm thick? Let's say the bar holding the plate is 4mm? So, 4mmx70mm=280 square mm of throttle body volume lost. 3848-280=3568. That is equal to a 67.4mm diameter pipe, just over 2.65" diameter. What size are your charge pipes? Still 2.5"?
Charge pipes, according to Garrett, should flow between 200-300ft/second ideally. OEMs are smaller than Garretts recommendations from what I can tell. Garrett is maybe giving ideal full boost drag scenarios to maximize their turbo power claims? This does seem like an obnoxiously large charge pipe.. let's take this with a grain of sellers salt.
8374 @79lbs/min = ~1150CFM ISO conditions? 3" pipe gives up a max velocity of ~350ft/sec.
Your 70mm throttle is seeing almost 500ft/sec with an 8374 at full boost, that should be a bit under that 600whp number you threw out earlier.
So, a 70mm throttle body is equal to a 2.65" charge pipe volume, but will see almost mach 0.5 near 600whp rotary. That sounds like a street setup that is happy a lot lower power, but can be pushed very hard for that dyno queen moment and occasional full power street pull. Like, it will do it, but not efficiently.
If anyone sees issues with the math, please point it out so we can correct it asap.
But really it all comes down to you arguing that OEM throttle sizing is way too large. I think you're stuck in the past when throttles were mechanical, and small blade movements were a problem. Now that we have DBW, a 10% foot movement can be a 1% blade movement off idle, removing that drivability concern of being "too large"
04-30-23, 08:51 PM
