Didn't get a whole bunch of time over there tonight, so I'll try to tackle a bunch tomorrow. I'm planning to get a new battery in there [Deka ETX30L] and finish/paint the rails. Also need to fill the coolant, bleed the rear brakes and hook up the parking brake. Not too much left.
[This message has been edited by 1986 Fiero GT (edited 10-02-2021).]
Well, now that I've sorted out that Photobucket cluster, I can get back to posting.
Here's what I've done for the past few days. Basically, I replaced the battery and finished the fuel rails.
Regulator beautifully tucks in. Almost like I planned it.
I also drained the tank of ~4 gallons of year-old fuel and poured in a bunch of fresh fuel.
I just need to fill the coolant, put the painted rails on and fire in the hole. Rear brakes need to be bled and I need to set up a clutch pedal stop to prevent overextending the Tilton as well. Those aren't necessary to fire it, though.
[This message has been edited by 1986 Fiero GT (edited 10-02-2021).]
Why are you making those fuel rails? Just for something to do?
I assume that's a fuel pressure transducer on your regulator? What engine management are you using?
Hah. Yea. I suppose. I bought one of those aluminum fuel cells from joesfiero when they were available. I had the fabricator add 3/8NPT bungs so I could run -8AN lines from the tank up. I'm using a Bosch 044 external pump. I may have gone overboard with my fuel system. The fabbed rails just made it easier to run the FueLab regulator and -AN lines.
Correct, that's a pressure transducer for a gauge I put in the rally pod, right next to Oil Pressure and AFR.
I'm using the Shelby computer.
Oh, and it works now.
Except for that pesky clamp on the coolant hose that I forgot to tighten. My bad.
Pops came to the rescue with a half gallon of 50/50 and a flathead to tighten the clamp. Runs better than last year. Idle is still a bit erratic, so I'll have to spend some time on that, but I'm happy. Clutch effort isn't much higher than previously, though pedal travel is obviously much shorter. It's still pretty forgiving for a twin disc though. Nice and smooth once rolling. Getting going just takes a bit of finesse.
[This message has been edited by 1986 Fiero GT (edited 10-02-2021).]
I'm in the same boat with photobucket, not sure what I'll do quite yet, not paying $400 per year for them to host my stuff though, I imagine I could host them myself for the kind of cash...
I've owned a domain for several years that I use for various purposes. I decided to set up an extremely basic Apache webserver in a fresh Unix virtual machine for the sole intention of hosting photos. Basically, I take a photo with my phone and I upload it via FTP over SSH into the appropriate folder, whether it's a Fiero or Triumph picture. Those are my only two folders as of now, but obviously the installation is extremely flexible. Then it's just a matter of posting the link in [IMG] tags. I end up resizing the photos to 853x480 for smooth, coherent forum viewing. It also cuts down on their size by a pretty significant amount.
The cost is free other than some hardware box to have powered on all the time storing the photos and your bandwidth. The vast majority of high-speed service providers such as Verizon FiOS or Spectrum offer enough upload bandwidth such that you'd be able to host some images without anybody being the wiser. Typically, residential agreements do not allow web servers. At least not publicly accessible ones.
I'll see how it goes for now and consider alternatives should the need arise.
[This message has been edited by 1986 Fiero GT (edited 07-03-2017).]
Hah. Yea. I suppose. I bought one of those aluminum fuel cells from joesfiero when they were available. I had the fabricator add 3/8NPT bungs so I could run -8AN lines from the tank up. I'm using a Bosch 044 external pump. I may have gone overboard with my fuel system. The fabbed rails just made it easier to run the FueLab regulator and -AN lines.
Correct, that's a pressure transducer for a gauge I put in the rally pod, right next to Oil Pressure and AFR.
I'm using the Shelby computer.
Oh, and it works now.
That is a bit of overkill. I have a '95 or '96 factory Corvette pump with '85 Fiero fuel lines that go up the left side of the engine bay and the factory SS fuel rail that puts both supply and return connections to the rear of the throttle body. With 19# Ford Motorsport orange top injectors and ~315 rwhp it works just fine... also with the Shelby computer.
I am thinking about seeing if an outfit like EFI Live can assemble a custom OS based on the Shelby which would run a drive by wire throttle. I think the fuel pressure is better off in the data stream than a gauge. If anything, I'd put oil temperature in an extra gauge. The C5+ Corvette oil level switch includes a temperature sensor. I'm not sure if it fits the Caddy oil level switch fitting, but I'll find out.
That is a bit of overkill. I have a '95 or '96 factory Corvette pump with '85 Fiero fuel lines that go up the left side of the engine bay and the factory SS fuel rail that puts both supply and return connections to the rear of the throttle body. With 19# Ford Motorsport orange top injectors and ~315 rwhp it works just fine... also with the Shelby computer.
I am thinking about seeing if an outfit like EFI Live can assemble a custom OS based on the Shelby which would run a drive by wire throttle. I think the fuel pressure is better off in the data stream than a gauge. If anything, I'd put oil temperature in an extra gauge. The C5+ Corvette oil level switch includes a temperature sensor. I'm not sure if it fits the Caddy oil level switch fitting, but I'll find out.
I suppose I just didn't want to ever have an inadequate fuel system. Ever. I'm planning a turbo within a year, and I think I'll be all set there. I've got no complaints on the Shelby computer. Last season the IAT input pin was shorted to the case, so the temp read all the way up. I also discovered that the MAP 5V pin was pushed into the case, so it wasn't sending voltage to the MAP - no pressure signal. It ran, but absolutely horked down fuel.
Those problems are fixed:
I dig the pressure gauge in the rally pod. I don't do anything with the data stream live while driving the car, so a gauge is better for me. I agree on the oil temp gauge, though. I had already spent so much on gauges; one had to go. Plus, I wasn't sure exactly where to plumb it. I'll definitely do one along with a boost/vac gauge with I put the turbo on. I love these Speedhut gauges.
I want to get some more seat time breaking in the clutch and shaking out any bugs. Next few days. I just discovered that the horn doesn't work and I need a front passenger side marker. NYS inspection is good for another month.
[This message has been edited by 1986 Fiero GT (edited 10-02-2021).]
Getting some clutch time in. I went and snagged the car on my lunch break. I love it.
Getting a bit of afterburn at the onset of some hard acceleration. Not sure what it's all about. I think I should replace the plugs and wires to be at optimal spark. Seem to run okay for now though.
Out of curiosity, what would you say a good idle oil pressure should be with 15w40? I'm getting 15-20psi cold and as low as 10-15psi hot, depending on idle speed. It jumps a bit at idle.
10-15 psi hot should be fine. The engine has similar main journal sizes to a Chevy.
Good deal. That's kind of what I thought. Here's how it sounds.
I think I want to get a Borla or something for it, especially after I get the turbo on there. It's a bit 'loud'.
Clutch seems to work fine. I've got a bout 150 miles on it now. Still a bit squeaky, but I've read that can continue for a bit. Grabs like a SOB, though. It's all I can do to not chirp the tires or peel out from a stoplight.
the car sounds awesome, easy way to fix the chirp, more tire! lol.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
Thanks! Yea, right now it's just straight 2.5" exhaust into a resonator. That's it. It's pretty loud and I bet it echoes off of things like hell. Still haven't gotten a noise ticket, but I bet it's just a matter of time. I mostly behave when the sun goes down, though.
EDIT: I plan on going with ~265-280 rubber when I finally do my hub/brake/wheel swap. We'll see what fits.
[This message has been edited by 1986 Fiero GT (edited 07-07-2017).]
If the tire chirp is a short-lived phenomenon (as in a second or less) that happens when releasing the clutch carelessly (on transients), maybe you could dial that out with some anti-squat.
If the tire chirp is a short-lived phenomenon (as in a second or less) that happens when releasing the clutch carelessly (on transients), maybe you could dial that out with some anti-squat.
It's usually just a quick chirp as the clutch engages. I can draw it out, but I typically don't.
Oh, and I literally just did a thing.
They were dirt cheap. I couldn't resist.
[This message has been edited by 1986 Fiero GT (edited 10-02-2021).]
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
10-15 psi hot should be fine. The engine has similar main journal sizes to a Chevy.
And the Northstar oil pump moves WAY more oil than pretty much any Chevy pump, and volume is the big deal at idle.
quote
Originally posted by 1986 Fiero GT:
I think I want to get a Borla or something for it, especially after I get the turbo on there. It's a bit 'loud'.
Clutch seems to work fine. I've got a bout 150 miles on it now. Still a bit squeaky, but I've read that can continue for a bit. Grabs like a SOB, though. It's all I can do to not chirp the tires or peel out from a stoplight.
Do you have dual cerametallic disks, or one ceramet, one organic?
For exhaust, this works well :
quote
Originally posted by Will:
I am Jack's underutilized sense of accomplishment.
It's usually just a quick chirp as the clutch engages. I can draw it out, but I typically don't.
Oh, and I literally just did a thing.
They were dirt cheap. I couldn't resist.
I already have two sets of, IIRC, '98-'99 GSXR 750 throttles, even spaced out for the Northstar's bore center. Those were the biggest single blade throttles that had integral injector bosses that were around at the time.
[This message has been edited by Will (edited 07-09-2017).]
C5 Corvette wheels fit with 1" thick adapters and 285/30-18's, as long as you have coil overs.
Good to know. I'm planning on a 5 x 4.75" hub swap for the convenience of C5 part availability, and I do have coil overs.
I suppose I didn't fully realize that these TBs have dual throttle blades. What's the benefit there? Is the factory linkage some type of progressive thing? Any way I can reasonably incorporate that? I'm fine with engineering a ridiculously complicated throttle linkage. I did read somewhere that the second set of blades was computer controlled or something. I suppose I could just remove the first set of throttle blades and convert these to single units, if I had to.
EDIT: The secondary throttle blades or STVs as they seem to be called, are for low-speed driveability and overall 'smoothness'. They're commonly removed from the motorcycles on which they're equipped. I don't believe they'll benefit the car in any meaningful way, so I'll likely do the same.
I did notice the second set of injectors. My plan was to plug all of the injector holes in the TBs and keep the factory Northstar style injectors in the same spot, directly outside of the ports in the head. Might even be able to re-use the fuel rails I just made. I don't want to lose all of my low end torque, so I'm thinking upwards of a 14" runner should do okay. I'm guessing there's already a place to plumb a nice MAP reference from each TB into a vacuum canister, so I can get a decent MAP signal. If not, I can make some rail-type vacuum logs to go into the injector ports behind the throttle blade and tie everything together for MAP. I might do that anyway in an attempt to make everything look better, and it could be a great place for an idle air control motor as well. I'll probably want to get an IAC on there so the thing is somewhat streetable. Looks like I might be able to just machine a bung for the factory Northstar IAC on the lathe and weld that into the vacuum canister. I'm thinking with the IAT, I could plumb that into just one of the throttle bodies. Intake temperature shouldn't be vastly different between cylinders, right? Then I just need to find a place for the TPS in the throttle linkage somewhere. No MAF for now, unless I decide to make an air box. Not so much a plenum, just a place for metered air to be stored before induction. I'd need one with a turbo anyhow.
Can't wait to get them physically in my hands and start figuring out the problems.
EDIT: Looks like 1.5" ID tubing runners will give me ~1.77in² runner area, which along with a 244ci V8 gives peak torque around 5,120rpm. Yea. That'll work. Looks like that jives with a 13-14" runner length. That's runner length from the back of the intake valve to tip of the velocity stack.
I'm also reading that I may want to consider getting the injectors further up as close to the butterfly as possible for better atomization. Makes sense.
[This message has been edited by 1986 Fiero GT (edited 07-09-2017).]
Do you have dual cerametallic disks, or one ceramet, one organic?
Dual cerametallic discs. I can see why the rally guys love them. They're pretty easy to modulate - almost slippable, but when you get your foot off of the clutch; it's locked. And the fact that everything from the flexplate to flywheel bolts and clutch cover nuts weighs 16lb and change, it revs to the moon almost immediately. Like, I can't get my alternator belt tight enough to prevent it squealing when I jam the throttle in neutral. That quickly.
I re-read bloozeberry's thread, and I like his belt setup that incorporates an idler and tensioner.
Might have to copy that sometime pretty soon. It's got a pretty nasty rattle that's I can't seem to track down. I can't tell if it's in the engine or transmission, but I think it's transmission. It's pretty prominent in low-rpm, high load situations; like accelerating in 5th gear.
Looks like that first set of throttle bodies will be here Tuesday, so I can start experimenting. Stoked.
quote
Originally posted by fieroguru:
Keep up the good work! This is one of my favorite threads to check out and see what you are doing!
Wow. That means a bunch, considering the source. Thanks!
I've always wanted a throttle per cylinder setup, but I realized it would be much easier to adapter the Y2K+ manifold to the '99 and older heads. The Y2K+ manifold has approximately the same length runners as the earlier manifold, but with larger cross section and significantly more plenum volume.
The adaptation process looks like it's fussy, but should be straight forwardly accomplished by bolt the heads to a mock up block, then clamping the block down to a mill table. From there profile the EGR flanges on the early heads for runner clearance to the new manifold. Six of the ten manifold bolts line up, so something will have to be done for the remaining four.
For throttle per cylinder, you'll need TWO vacuum collection circuits. One for MAP and one for IAC + vacuum accessories like the brake booster. The flow through the IAC circuit will affect the MAP numbers.
That being said, a guy I know in the Ferrari community built a throttle per cylinder V12. He has 12 MAPs and a circuit that looks at all 12 and pulls whatever reading is the lowest at any given time. This system gives him a stable signal and tremendous resolution. He has big hefty cams and the simulations say the engine should make power above 9000 RPM, but his idle MAP is rock solid at around 40 kPA. Crazy... 18 inches of idle vacuum on a 9000 RPM engine. Of course with his idle MAP that low, he has great resolution on the load table and the system obviates the need to run Alpha-N control.
Dual cerametallic discs. I can see why the rally guys love them. They're pretty easy to modulate - almost slippable, but when you get your foot off of the clutch; it's locked. And the fact that everything from the flexplate to flywheel bolts and clutch cover nuts weighs 16lb and change, it revs to the moon almost immediately. Like, I can't get my alternator belt tight enough to prevent it squealing when I jam the throttle in neutral. That quickly.
I re-read bloozeberry's thread, and I like his belt setup that incorporates an idler and tensioner.
That might work for you weird New Yorkers who ditch air conditioning... But we can't do that in VA. Summers are just too humid. I'm pretty sure that the stock belt routing with the idler in between the A/C comp and alternator would solve the belt squeak problem. I have a part in my head to mount the tensioner about where it is in the photo, but use one that twists to keep the belt drive below the stock battery tray. Thanks for reminding me about that. I'll implement it when I get back from the 'Stan this fall.
[This message has been edited by Will (edited 07-10-2017).]
That might work for you weird New Yorkers who ditch air conditioning... But we can't do that in VA. Summers are just too humid. I'm pretty sure that the stock belt routing with the idler in between the A/C comp and alternator would solve the belt squeak problem.
Don't nobody got time for A/C. Sometimes I wish I had it, but then I put my my foot down and create a nice breeze.
You think just the idler would work, without the tensioner? You're probably right. It's kind of tough to get in there to work with the motor in, so that may be a "this winter" project.
First round of throttle bodies gets delivered today. Hell yea.
[This message has been edited by 1986 Fiero GT (edited 10-02-2021).]
Negative; need the tensioner. I was pointing out that with the OE idler configuration there would be more wrap on the alt belt.
Is this kind of what you're talking about?
That method gives ~60% alternator pulley wrap as opposed to the current <50% and Blooze's ~40%. I'll play with it once I get the spare block/heads assembled for ITB mockup. Maybe I can do that tonight. I can make some bootleg studs on the lathe real quick just to hold the heads on the block.
I developed that tensioner placement. My setup has the A/C compressor, though.
Thanks. I found that picture in ryan.hess's thread and he gave you credit for it. Something like a 52" belt? I don't have either the idler or tensioner. Hopefully eBay pays off.
So here they are after I pulled them out of the box and stripped them of most of the unnecessary stuffs.
The primary [lower] throttle blades - 40mm, which according to popular ITB references, should support 50-56bhp per cylinder at 500cc displacement per cylinder. Perfect!
And the secondary [upper] blades - 45mm, which were removed. They're for low-speed engine stability and prevent choking the engine with too much air at once. They're not necessary on the car, so they're gone.
I had trouble getting the screws holding the butterfly valves to the shaft broken loose on the secondary blades, so I drilled them out instead. Much better. I'll have to plug the holes in the sides with appropriately machined aluminum plugs. Pressed and welded, of course.
So these units are a bit tougher because instead of being four individual units attached together, they're a pair of two, joined in the middle. The bore center offset is approximately .603" at each bore or 1.205" for each pair. Clearly visible.
...and the gap between the pairs required to at least center the TB pairs over their respective ports.
I calculated using various sources that a ~1.5" tube runner will give me a ~5,100RPM torque peak, and a ~14" runner length will allow peak power to be built about 7K. The intake port to back of intake valve is ~4.5", and the TB is 3.5". That gives 8", and with a 2" velocity stack leaves ~4" for transition from head to bottom of TB. Can do. Might have to hand form some custom elbows out of sheet metal, but I'm into it.
Looks like the factory throttle blade shafts are 10mm. I'm going to machine two fittings that attach to the inner end of each TB 'unit' and attach together with a short piece of 10mm shaft. That shaft is the perfect place for a 50T steel spur gear driven by a 15T steel pinion, for a 3.33:1 reduction. This will be further reduced by another 50T/15T combo to a NEMA17 stepper motor, for a total reduction of ~11.11:1. I bought five Matsushita NEMA17 motors that claim 76oz/in holding torque, I'm guessing in a bipolar configuration. Only really need the two, though. Unipolar configurations don't seem to have the same holding power, though the electronic drives necessary are less complex. Interfacing H-bridge motor drivers to Arduinos is a pretty easy task, so I'll go bipolar drive for the speed and torque benefits. That 76oz/in is .537Nm and into an 11.11:1 reduction, becomes 5.996Nm holding torque. Should be plenty to overcome a throttle return spring as well as open the butterflies pretty quickly. I found this overpriced, overgrown servo designed for throttle actuation and it only claims 3.6Nm from a 20:1 reduction on a .18Nm motor. Substantially weaker. That just leaves interfacing a Penny & Giles TPS280DP throttle position sensor for pedal position feedback. It's electrically the same as a standard analog potentiometer/voltage divider based TPS, but features its own little microcontroller and a hall effect sensor for greater resolution and sensor reliability/longevity. Plus, it's got two outputs; one for the ECM and one for the throttle actuator. I've got an el-cheapo Ford TPS which I've just tested with a multimeter and verified compatible with the .5V - 4.5V analog TPS standard. The throttle actuator controller can be as simple as an Arduino running a basic sketch using the MotorKnob library. Connect the TPS output to analog in on the Arduino, program it for .5V or lower as 0% throttle and 4.5V or higher as 100% throttle. The Arduino sketch then positions the stepper motors accordingly. I'll start prototyping that soon. I ordered H-bridges and stepper motors. I'll order the necessary gearing likely this week, after I get the stepper motors spinning.
I also looked at the injector ports. Suffice it to say, they wont work as is.
As the last picture shows, there's a bit of interference with the fat injectors and the fuel rail mounting post. I'll likely have the skinny-style injectors for this intake by the time it's ready to go on, so I'm not sure that's relevant. I'll need to make some type of adapter bung to get the injectors to fit properly. Wish I had a mill. Looks like I could just bore the injector ports a bit larger to fit the Bosch automotive units if I could clamp it to a solid table from which to indicate. Would injector spacing from the runner itself have any meaningful effect on the spray pattern? I would have to imagine it does, and I would want the injector to spray as closely to the runner as possible, right?
I want these to be DBW. I don't know why. I just do.
Thinking about anodizing the throttle bodies themselves red and putting gold velocity stacks on them. Everything else black. Thoughts?
This is exciting.
[This message has been edited by 1986 Fiero GT (edited 10-02-2021).]
Couldn't wait. Ordered a gear train. Steel pinions, plastic spurs. If they're good enough for 1/8 scale R/C buggies, they're good enough for throttle body actuation. Overall 12.29:1 reduction, giving me ~6.6Nm holding torque from each 'servo unit'. One servo per bank, with a sturdy return spring, mainly for safety. The TPS voltage dropping when I take my foot off of the throttle should be enough for the steppers to return back to closed, but that's not a chance I'd be betting on.
So I've got my throttle bodies, stepper motors, h-bridges, gear train, Arduino, test TPS and everything else I need to get something together. I'll need to make two hubs on which to combine a 56T/15T idler setup for each side, and two 10mm shafts with integral hubs for 56T spur gears to go in between the separate pairs of TBs and join the butterfly shafts. I'll work on drawing that stuff up in the next couple days and maybe making some of it.
[This message has been edited by 1986 Fiero GT (edited 10-02-2021).]
The spring will take the dead space out of the mechanism.
Are you looking at having the two banks mesh in order to guarantee that they stay synched?
This. The spring is required in my mind.
I started thinking about that after I decided to go with two separate throttle actuator servos. The stepper motors will be driven via parallel-wired, yet independent DRV8825 H-Bridges. Movement should electronically be mirrored between banks, but I should physically link the two banks of throttles via two pushrods and a bell crank on a vertical central pivot. You know, like a straight 180° bellcrank mounted on a horizontal plane parallel to the crancraft and central between both butterfly shafts, all connected via heim-joint'd pushrods and ball bearings everywhere for near zero lash? When the bottom of one butterfly shaft moves in, the bellcrank naturally pulls the other in; especially in the case of servo failure. 6.6Nm is almost double that other servo. Perhaps one of my 'Super Servos' could handle all 8 throttles? I need some type of watchdog in my program to alert me of any kind of servo fault.
This kind of crap gets me pretty excited. I likes mathing.
Got the other set of throttle bodies today and promptly stripped them all the way down.
Drilled out the secondary blade butterfly screws and removed all of that garbage. You can see here how Mikuni swage the tip of the primary butterfly screw in addition to LocTite after installation. I wouldn't worry about these finding their way into the motor. Until I removed them and jacked that up, of course. Hah.
So then I got my temporary threaded rod in the new set there to space the units apart 2.25" to match the others and couldn't resist setting them next to each other at a bore spacing that I thought would look somewhat reasonable.
And then I had to drop them onto an upside-down intake manifold to give me an idea.
Yeesh. That looks awful. Not symmetrical, super wide bore spacing [9-5/8"] - just looks bad. It doesn't help that I haven't shaved the now unnecessary aluminum bits off of the TBs yet, but I can at least look past that. Instead of using 2" velocity stacks on the outside opening of the TB, I can just add that 2" to the TB - intake port runner, giving me 6" for those. That will precipitate the use of either zero length trumpets or nothing at all on the openings of the TBs. Also, although the intake flanges on the heads are flat horizontal, the port through the head to the valve pocket is, of course, not vertical. It's foolish to simply drop perfectly vertical TBs directly onto the flange without some type of compensation. Instead, I'll align the TBs for symmetry and move each bank a bit closer together; something like ~7-7.5" bore spacing. This will require some gradual sweeping runners bent/rolled at something like 18"-24" CLR. Not too sure yet. I want to get the throttle actuators setup and the TB banks themselves joined before I make an intake manifold for it. I plan on using those threaded rod bosses as anchor points for a ladder frame to hold all four TB 'units' together before attaching the runners.
Another inherent benefit is the ability to run a single common fuel rail for all eight injectors. I discovered that the injectors appear to be positioned at a 45° angle to the vertical TB. Interesting and convenient. I'll measure to verify, but this means that I should be able to use two adjacent sides of a piece of 1" square tubing and eight more injector bungs to make the singular required rail.
You can kind of see what I'm on about here:
I'm going to work on a jig with which to make that ladder frame for the TBs this weekend. I'd like to get them all assembled into one unit first before worrying about placing the fuel rail, both vacuum collection circuits and finally, both servo drives and controller module. Then, finally, get all of on the intake flanges and runners. I'd like to keep them as three separate pieces. The two intake flanges/runners and the TB assembly.
[This message has been edited by 1986 Fiero GT (edited 10-02-2021).]
Instead of using 2" velocity stacks on the outside opening of the TB, I can just add that 2" to the TB - intake port runner, giving me 6" for those. That will precipitate the use of either zero length trumpets or nothing at all on the openings of the TBs. Also, although the intake flanges on the heads are flat horizontal, the port through the head to the valve pocket is, of course, not vertical. It's foolish to simply drop perfectly vertical TBs directly onto the flange without some type of compensation. Instead, I'll align the TBs for symmetry and move each bank a bit closer together; something like ~7-7.5" bore spacing. This will require some gradual sweeping runners bent/rolled at something like 18"-24" CLR. Not too sure yet.
All of this goofiness is why I elected to try the Y2K+ manifold first. -Can't come straight up off the manifold flanges. -If the throttles are in line with the ports, then the runners have to cross and interleave. The bore center and diameter mean they can't be round where they cross and the bank offset requires that they each offset to one side a little bit. -Mounting the throttles vertical over the V requires fabbing EIGHT 45 degree round-to-square transitions WITH injector bungs, AND moves the throttles further from the valves, softening the throttle response that's one big reason to implement throttle per cylinder.
Then you can spend a long time optimizing injector placement and targeting, which can require building several iterations of EIGHT 45 degree round-to-square transitions. Optimum injector placement varies with RPM, so you end up having to pick the RPM range over which you want the best mixture quality and letting other ranges drop a bit.
[This message has been edited by Will (edited 07-14-2017).]
I think I'm going to shelve the 06-07 TBs and focus on others. I just don't think they're ideal for this application.
So, I found these Triumph joints that are pretty clutch. They're from a ~2001 TT600. They don't have a whole bunch of extra junk on the casting, they don't have secondary throttle butterflies and they're individual units. I spent $35 on a set of them to check them out. There are only two small caveats with those TBs, and they're not really a big deal. One is the lack of injector bungs machined into the TBs which probably wouldn't be the right size anyway, and the other thing is the lack of vacuum ports on the TBs. I can add injector bungs and vacuum ports in the runners easily enough.
With respect to distance of injector from valve, it's my understanding that OEMs typically put the injector as close to the valve as possible for emissions, economy and low-engine speed stability. For high-RPM performance, I've read that injectors placed further from the valve, like at the butterfly or even further past, can allow for a better atomized fuel charge. Part of the reason those crazy Honda dudes use standoff injectors that kick on at like 4,500RPM+.
I also found these which appear to be a popular option for Porsche enthusiasts that desire ITBs. There's a fella selling Porsche kits based on these TBs on eBay. Triumph Sprint 955i throttle bodies. These might be better, especially because of the Triumph stanp in the casting, but seem to be from a British-only 3-cylinder, and I'd need three sets. These are $100-$150 per set from the UK, so it would get spendy. They truly are perfect, though.
The independent TBs will allow me to try to copy this Kinsler setup that I fell in love with yesterday.
[This message has been edited by 1986 Fiero GT (edited 10-02-2021).]
With respect to distance of injector from valve, it's my understanding that OEMs typically put the injector as close to the valve as possible for emissions, economy and low-engine speed stability. For high-RPM performance, I've read that injectors placed further from the valve, like at the butterfly or even further past, can allow for a better atomized fuel charge. Part of the reason those crazy Honda dudes use standoff injectors that kick on at like 4,500RPM+.
Don't duplicate this. Conventional port injectors spray a stream. To correctly use upstream injectors, you need "shower" injectors that are configured for a wide angle spray pattern and small droplets in order to end up with a more homogeneous mixture at the valve.
quote
Originally posted by 1986 Fiero GT:
The independent TBs will allow me to try to copy this Kinsler setup that I fell in love with yesterday.
I've been musing for a while that one could machine a block with 8 throttles on a common shaft and position it over the Northstar V like this where the runners intersect. Due to the bore spacing the throttles would have to be rectangular and the fabbed adapters still have to compensate for the bank offset... and the trumpets would have to transition from rectangular to round.
Don't duplicate this. Conventional port injectors spray a stream. To correctly use upstream injectors, you need "shower" injectors that are configured for a wide angle spray pattern and small droplets in order to end up with a more homogeneous mixture at the valve.
I hadn't planned on it. I was just referring to that extreme type of setup where super high-RPM applications benefit from "as far away as possible" injectors, several inches in front of the butterflies.
I plan on putting the injector bungs right into the runner behind the throttle blade, such that they fire straight down the center of the runner toward the valve. I think that's an ideal type of situation for a 7K torque peak. I did my math wrong and it looks like a 1.75" round runner will give me a 6,9XXRPM torque peak. I kinda like that better. I mostly live at 3K+ anyhow. So, 1.75" OD .125" wall tube is 2" OD and the Northy has pretty damn near 4" bore spacing, so that's pretty perfect. This only thing I have to check now is if I can maintain a perfectly smooth intake tract inside of a 6" intake flange-to-TB runner and have the TBs surpass each other enough such that I can pull one of those beautiful crossrams
Either way; I can sit here and do math all day long, but it may not even necessarily turn out to be representative of what I end up with in real life. That's always the worst. But I think I'm good with 1.75" ID, 13-14" length max runners and these 40-42mm TBs with a lightly curved, straight-as-possible intact tract. I'm not entirely sure what the Triumph units are diameter-wise. Hopefully I'll get those this week.
I feel like I need to call Alan and get cams.
[This message has been edited by 1986 Fiero GT (edited 07-15-2017).]
I dig the pressure gauge in the rally pod. I don't do anything with the data stream live while driving the car, so a gauge is better for me. I agree on the oil temp gauge, though. I had already spent so much on gauges; one had to go. Plus, I wasn't sure exactly where to plumb it. I'll definitely do one along with a boost/vac gauge with I put the turbo on. I love these Speedhut gauges.
My point is that once it's tuned, there's no point in watching mixture or fuel pressure, as EFI is extremely reliable. Oil temp can vary significantly based on use case and you never really know if your cooler is adequate until you abuse the heck out of the car. Of course in the track day scenario logs work as well.
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