# 1 fuck given

3/12/2012 9:59:01 PM

for page 5

Quote :

"noone gives a fuck"

3/12/2012 10:04:58 PM

3/12/2012 10:59:41 PM

golbasi984 = 69 exposed????

3/13/2012 8:14:19 AM

Control systems for automatic transmissions have changed significantly over the years, resulting in closer integration of a bunch of subsystems. Originally, everything was mechanical, based only on pressure differences among hydraulic circuits in the valve body. Electronically controlled transmissions came in during the late 1980s.

So the old way of electronically controlling a transmission (late 80s through 90s) was that you fed some signals to the transmission control unit and it reacted to rpm, TPS, and temperature inputs for the most part. Then electronic throttle was introduced in the late 90s, and you get an architecture like this:



You've got an accelerator pedal position sensor signal feeding into two control paths, and then compensation algorithms for shifting, traction/stability control, vibration concerns, etc. Well that gets really complicated, especially as you add more control modules. Integrated control provides a more elegant solution:



That's Toyota's implementation of integrated powertrain control. You utilize models and have the integrated controller coordinate the transmission and engine to achieve the target wheel torque/power. That also feeds into the engine dynamics control (stabilty control etc). The integrated engine controls help reduce vibration and fix the torque drop off between shifts if that's what the calibration calls for. You have to have a model to transfer target drive power into a torque request, and then a model to execute the torque request through actuator commands.



This system was implemented on the AA80E transmission used in the Lexus LS and IS-F and has probably trickled down to most vehicles Toyota makes for this market by now.

3/17/2012 8:31:05 AM

The GM "Turbo-Jet" engine family, including the 396 and 427 cubic inch variations, replaced the venerable 409 V8. This engine family improved intake airflow through a better combustion chamber design and valve arrangement:



You can see that the Turbo-Jet engines (above, and left) used a wedge-shaped combustion chamber with a more gradual transition from the intake runner to the valve and port itself.

3/19/2012 9:03:43 PM

The Mazda 6 uses an Aisin 6 speed automatic (FWD/transverse) transaxle that has similarities with many other 6 speed transmissions in the industry.



Modern 6 speed (or greater) transmissions utilize a Ravigneaux gearset . A Ravigneux gearset has a front and rear sungear, a shared set of pinion gears and an additional set of pinion gears used only for the rear sun gear. A diagram illustrates better:



You will see clutches and brakes utilized to engage or hold stationary different elements of the gear system. This transmission uses a brake band/servo (B2) to hold the rear pinion carrier but many competing designs don't use bands at all anymore. These diagrams show powerflow for 1st gear, 4th gear, and reverse:







As you can see, it's pretty damn complicated.

[Edited on March 25, 2012 at 11:17 PM. Reason : .]

3/25/2012 11:16:42 PM

On page 2 I mentioned hot-wire mass airflow meters. There are two types of these meters: one in which the sensing wire samples directly in the main stream of intake air, and another where the air is routed into a bypass passageway. Both have their own set of tradeoffs in terms of flow restriction, power consumption, and sensitivity to flow and pulsation effects.

For a MAF sensor sampling directly from the main air stream, a mesh of some sort will be found in front of the wire. The mesh is intended to condition the airflow in front of the wire in order to have a more accurate signal. The chart from an old Bosch study shows the sensitivity of this type of MAF sensor to not having a mesh. At low airflow levels (solid line), the sensor reading can deviate greatly.



The design of the sensing wire and MAF housing affect this sensitivity.

3/27/2012 8:34:02 PM

The Bugatti Veyron Grand Sport and Audi R8 are both Volkswagen supercars in a way but I find their choices of suppliers interesting:





There are a few random Japanese and American companies thrown into the mix. I wonder how many of those parts were actually made in Europe?

4/1/2012 12:18:50 PM

HALP!!!


the new gt500 is making 650 whp on 15psi out of a 5.8 liter

The new ford racing supercharged 5.0 makes 624 hp on 9psi .


what did they fuck up on the gt500 to make it have more displacement and need 6psi more to reach +26 hp over the supercharged gt.

Do the heads suck? Do the cams suck? wtf?

4/6/2012 9:02:30 AM

need more info on this 5.0. Also, the GT500 should be actually SAE certified at this power level. I am curious about how they arrived at the 5.0's numbers and under what conditions they were using to get those numbers. I'd also like to see the power and torque bands for both, with more specs on all the differences between the exhaust systems, emissions levels, NVH levels, and durability testing.

What I suspect is that the GT500 is quieter, cleaner (in terms of emissions), much more durable and thoroughly tested, and probably has a broader torque band.

[Edited on April 8, 2012 at 9:25 AM. Reason : .]

4/8/2012 9:17:14 AM

http://www.autoblog.com/2012/04/07/ford-racing-reveals-its-latest-mustang-project/


http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=12402


more durable? yes probably it's lower compression and larger displacement.

cleaner ? Maybe that's really up to the tune the coyote hasa very efficient combustion chambers and the best flowing heads ever made for a small block ford.

Quieter? Doubtful, a twin screw at 9 psi vs a roots at 15psi. I don't see how the engine could possibly be quieter.



[Edited on April 8, 2012 at 12:19 PM. Reason : .]

4/8/2012 12:13:03 PM

http://www.mustang50magazine.com/techarticles/m5lp_1105_ford_mustang_kenne_bell_supercharger_5_0_coyote_vs_5_4_condor/viewall.html

Interesting article. Pretty much compares the 5.0 withy the 5.4 with the same blower. My favorite part is at the end where they say they never ran the 5.0 on the dyno with over 15 psi because it blew up........... The oil pump because the new lower pulley/harmonic balancer didn't agree with it.

I would have thought with 11:1 compression at 15psi that the motor would actually just blow up all together not just the oil pump. This thing must be a friggin tank of an engine.

4/9/2012 6:55:08 AM

bump by request from Air, who wanted to talk about ABS systems in the context of an ABS retrofit.

Please provide as many details as possible...

10/20/2012 4:25:56 PM

Well, hoping for some more theory from someone who understands better than me how the electronic signals work, but here is what I understand so far:

My goal is to retrofit ABS of some sort onto my 93 240sx.

Here is the fluid diagram of the braking system with and without ABS


Notice the rear brakes are controlled as a unit. This is to prevent adding yaw to the car by unevenly braking the rear wheels individually. Even a 4 channel ABS system will brake the rear wheels together, the 4th channel is utilized for traction control and not ABS.

Here is the Hydraulic circuit inside the ABS Actuator unit (commonly referred to as the "Pump")


Fluid comes in already pressurized and biased (rear gets less pressure than the front)

The Actuator operation is described here:


During normal operation, the Inlet valve is open and the outlet valve is closed. This allows direct master cylinder pressure to reach the caliper.
When the Inlet valve is switched "ON", the circuit between the caliper and the actuator is cut off from the rest of the system. Whatever pressure is in the caliper at the time will remain in the caliper while this valve is in the "ON" position.
When a large deceleration is seen (wheel rotational speed decrease) the pressure to the caliper is reduced to prevent the wheel from stopping (car moving but wheel not rotating). This is accomplished by switching the inlet valve and outlet valve to the "ON" position. Even though the drivers foot is still on the brake pedal, the pressure is reduced by the pump pushing fluid back into the master cylinder (hence why the pedal pushes back against the drivers foot)
When the resulting acceleration in wheel speed is seen, the pressure to the caliper is increased again by closing both valves (the normal position). This allows master cylinder pressure to reach the caliper.

The important thing to notice here is that the hydraulic pressure used to squeeze the pads into the caliper is always generated mechanically by the drivers foot. The "pump" actually FIGHTS against the drivers foot in order to reduce braking pressure. When you mash the pedal in your car hard enough to engage ABS, the vibration you feel in the pedal is the pump forcing your foot away from the firewall. In this system, a ABS system failure will only result in ABS not working, not the entire braking system failing.

The valves switching from off-on-off-on ect is the noise that is heard. THe frequency of the on-off-on-off cycle is important, as the faster it can react the more closely it will approximate a driver who is "threshold braking".



The wheel speed is determined by a reluctor ring and a sensor. The sensor consists of a magnet wrapped with copper wire. As the reluctor ring passes by the sensor, it generates a sine-waveform. As the speed of the wheel increases, the frequency of the waveform also increases. This is the part of the system that I do not fully understand.

I am not sure how the computer accounts for the rapid change in wheel rotation. Does it convert waveform frequency into "rotations per second"? The reasoning behind my inquiry is that finding 240sx ABS is difficult, but finding Q45 or J30 ABS is easy. I am not sure about the number of teeth on Q45 reluctor rings vs 240sx reluctor rings. Would this matter to the final system?

10/21/2012 7:05:38 PM

are you wanting the abs for extra safety on the street? I've never wanted it for a track application due to extra chassis input from the pulsing upsetting the suspension

10/21/2012 8:18:04 PM

What you described is almost every late 80s/early 90s ABS system on a front engine, rear-wheel drive car. It's exactly like an FD Rx-7 for example; Nissan and Mazda probably had the same supplier. Here's a nice illustration of these oldschool ABS controls at work:

Quote :

"Notice the rear brakes are controlled as a unit. This is to prevent adding yaw to the car by unevenly braking the rear wheels individually. Even a 4 channel ABS system will brake the rear wheels together, the 4th channel is utilized for traction control and not ABS."

The reason you have a 3 channel system where the rear axle is controlled together, is primarily for cost. It's just cheaper to do it that way. I suppose you can boil almost every engineering decision down to money in some way.

It kind of depends how you are looking at it though. If you are comparing it to other 20 year old systems, then yes. You can get away without a 4 channel. The NSX had a 4 channel system though. Where this whole situation gets murky is, looking at it in the year 2012, ABS, traction control, electronic brakeforce distribution, torque vectoring, and stability control are all kind of integrated concepts. They're part of a bigger picture. But we need to go back in time to the late 80s here for this discussion. So we can get bogged down in semantics and comparisons of literally decades worth of technology differences.

These oldschool systems just control wheel slip ratio within some range using a basic controller. For the most part they don't calculate torque, yaw rate, steering angling, etc. They don't have access to the information they need to do anything more. Modern systems have a bunch of modules talking to each other and integrate much more sophisticated calculations.

Quote :

"The wheel speed is determined by a reluctor ring and a sensor. The sensor consists of a magnet wrapped with copper wire. As the reluctor ring passes by the sensor, it generates a sine-waveform. As the speed of the wheel increases, the frequency of the waveform also increases. This is the part of the system that I do not fully understand. I am not sure how the computer accounts for the rapid change in wheel rotation. Does it convert waveform frequency into "rotations per second"? The reasoning behind my inquiry is that finding 240sx ABS is difficult, but finding Q45 or J30 ABS is easy. I am not sure about the number of teeth on Q45 reluctor rings vs 240sx reluctor rings. Would this matter to the final system?"

Question: Can I swap a 12 tooth crank position sensor pickup in for a 24 tooth crank position sensor?
Answer: it's a bit of a trick question. It depends on the design and how fast it's spinning.

The reason I bring this up is because the 24 tooth crank angle sensor on a 2nd gen Rx-7 produces the same waveform as the 12 tooth crank angle sensor on a 3rd gen Rx-7. The difference is that the 24 tooth sensor is driven at half the speed because it runs off a distributor-style drive gear. So the question for you to think about is, will the waveform be the same?

Let's look at this diagram from the 91 NSX service manual which illustrates an ABS speed signal waveform. It's basically the simplest/cheapest electronic speed sensor you get... it only counts # of revolutions, like an old distributor signal. It doesn't resolve position, like a crank or cam angle sensors.



does that clear things up? Have you tried the obvious--going to NAPA etc and asking for ABS reluctor rings for a 240sx? You're rolling the dice a little bit but if you can't find a used one, you can't find a used one.

10/22/2012 12:01:23 AM

Know anything about roll cages and the ability to build one suitable for an 8.5 sec+ car in NHRA, then meet the typical standards for NASA & SCCA too ?

11/5/2012 8:41:57 AM

^I'd refer to each respective organization's handbook, first, and look for cross-references or similarities as far as design goes. (not to steal ray's thunder)

11/5/2012 10:01:51 AM

What he said. ^

11/6/2012 10:30:59 PM

yeah... i did....

NHRA is over kill for compared to the rest but the tube locations aren't where they want them so i don't know how it would go.

11/7/2012 7:18:30 AM

you talking about lateral bracing?

11/7/2012 8:37:34 AM

yep.... not just the hoops

11/7/2012 12:34:16 PM

ok... so mustang 2 style suspension vs strut-type?

11/19/2012 11:53:37 AM

^ better yet, just go ahead and cover everything! trailing arm, wishbone, multilink, macpherson, cross beam, solid axles w/ leaf springs, w/ coils, w/ watts link, etc.

11/19/2012 2:01:03 PM

^bah

strut like 'drag-car' struts, or 'OEM car' struts?

11/19/2012 2:39:37 PM

Struts like coilovers on a new mustang would be.

Told you, jack of all tracks.

11/19/2012 3:00:06 PM

I'd have to dig up some stuff... my knowledge of 70s solid axle passenger car suspensions is not especially deep, and to be honest so far I haven't found the topic interesting enough to make it a high priority-- discussing it is like listening to geezers argue about carburetors.

I've been looking into early mass produced turbocharged engines lately (60s, 70s, and early 80s). It's actually pretty relevant to both production and modded engines today. There's a lot of interesting nuggets to be found. Did you know the first Porsche 911 turbo had a 6.5:1 compression ratio and external wastegate running over 11psi boost?









[Edited on November 19, 2012 at 8:30 PM. Reason : turbonium]

11/19/2012 8:13:19 PM

None of what I mentioned is solid axle.


Basically macpherson strut or ~meh double wishbone.

11/19/2012 11:28:30 PM

Mustang II has a solid rear axle, like every other Mustang except forgettable Cobra independent rear suspension. So that's what I thought you meant.

[Edited on November 20, 2012 at 5:51 AM. Reason : Mustang "2" = 1974-1978 Pinto-based Mustang]

11/20/2012 5:39:50 AM

Sorry I'm talking front :-) rear I'm doing triangulated 4 link with a watts link

11/20/2012 6:28:47 AM

The main reason for the gt500/ vs coyote gt hp discrepancy is simple, it's not a vvti engine and has some boreing cams for emission. Obviously meaning its got a completely different set of heads on it. AAaannnnnddddd it's a spray bore engine which I still don't trust after the Lincoln/jag 4.0 fiasco.

Weisco is making a 5.8 stroker kit for the 5.0 though.

11/27/2012 6:58:48 AM

'splay' bore?

11/27/2012 7:20:24 AM

nope.... spray bore...

http://www.sae.org/mags/aei/7624

last time they did this was the teflon-like shit on the lincoln blocks... it allows them to not have to run sleeves in aluminum.

my feelings are as follows...

great it helps hold piston friction... but is the bore it's -self as rigid as when it was sleeved?

but still this is essentially a welding wire spray gun... which is fucking awesome and i want one waayyy cooler then the old Nikasil-coated cylinder crap.

look mahh... the black shit on your pans.... now... in my engine...

(waiting for our resident porsche-ophile to come in and exclaim how it works fine for them.)

[Edited on November 27, 2012 at 8:11 AM. Reason : .]

11/27/2012 8:01:45 AM

Hey arghx

I would like some lessons in quench!!

4/25/2013 10:16:48 AM

I've been away from Tdub for a while. I'm actually in Raleigh this weekend for a wedding.

What do you mean by quench? I think people use the term "quench" as a positive thing when they are referring more to squish flows. Basically, you've got gas flows that occur near the top of the compression stroke that create turbulence. The turbulence influences combustion efficiency and knock resistance. Typically you'll see it on the edge of a combustion chamber from the shape of the head and the piston, when people talk about the "quench zone." On a diesel, squish flows work with swirl flows for improved mixture distribution.

"Quenching" as I think of it, is when a flame is extinguished, leading to unburned gases. Squish could lead to quench, but quench doesn't always lead to squish. Or at least, that's the way I'd like to think about it. I think they're talking about areas designed to induce squish flow, a side effect of which may be quenching. Generally speaking, quenching a flame isn't a good thing, but the right kind of turbulence (squish, swirl, tumble) is.

A squish-oriented combustion chamber on a gas engine is starting to become an outdated design used mostly for port injected engines. For direct injection, high tumble flow is the trend, at least for DOHC engines. The new direct injected K24W Honda engine (new Accord) is a high tumble concept. The new GM smallblock (Gen V LT1 etc) uses a significant amount of swirl flow but that is a totally different combustion chamber shape.

5/3/2013 9:13:36 AM

squish flows.


Thinking about putting a .080 head gasket on a .030 on a 9.6/1 compression engine down to a 8.6/1 compression to turbo it (both at a later date).... what issues will be cause on a wedge engine...

Its got 88cc heads -17 cc dish on a big block ford.

5/3/2013 10:26:39 AM

dude, in my experience... the things that cause "issues" on custom turbo cars are

1) overboost & lack of overboost protection (boost cut, fuel cut, etc): wastegate hose melts etc
2) insufficient safety margin in ignition timing, see #3.
3) inability for tune to compensate for changes in weather or engine conditions. Summer turns to fall, car feels really fast right before it blows up.

the rest of that shit doesn't matter nearly as much.

5/3/2013 11:06:06 AM

10-4... .

she's stand aloned with boost control and timing control.

5/3/2013 11:09:44 AM