ITS Ford Mustang(s) Build - Stripper Stang Part II

Finally found part of the last lap, the checker with a car length between us.

[ame]http://www.youtube.com/watch?v=14rrb7oXmYc[/ame]

Work still continues with rear axle rebuilding, tri-link re-engineering, chassis setup, and some other odds and ends. I believe we've made significant strides in the rear chassis configuration/setup and will be able to put power down far sooner than we were able to in 2012/2013. That's really the key for us, to be able to capitalize on our good low and mid-range horsepower. At a track like say CMP we can turn in just fine and brake with the best of them, but lose on power application in the carousel, a very important section of the track, as well as T12. CMP doesn't have long straights so the RX7s can't kill us on top like Daytona or CMS, and if we can get that power down early without losing the rear we might do well at that track. And those improvements would help a lot at RRR where the race is to see who can lay down the pedal soonest in T6.
 
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Development heavily continues over in camp stang. The new rear end geometry is working out extremely well and along with our properly re-valved shocks, plus a lot of testing, we’ve really improved our cornering and corner exits. We’re learning that the car is more sensitive to ride height than we initially thought. It is more complicated that stated, but it is sort of where 11-12mm in ride height can make the difference between a properly handling car and one with understeer. When it is spot on though the car handles precisely, with a slight tendency to oversteer, and is a great point and squirt machine.

Over the past couple of months we’ve been working with Burns Stainless and a header builder, Calvin Elston. We knew that our exhaust had some shortcomings and Calvin and Vince have conspired to design a system that would be our final exhaust design. So, after one of our race weekends I dropped the car off at the shop and waited about four weeks for the final product, and wow is that a nice exhaust system he put together. Exhaust V3.0 is really well done from flanges to tail pipe. There are a number of aspects about it that are greatly improved over the earlier headers; water jet flanges that precisely match the ports, lots of upper roof port flow, equal length to within 0.5", three newly sized collectors, newly sized primaries and steps, anti-reversion collector for the final section, and all made out of stainless that might also drop some weight.

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It's hard to see from the pictures, but they are elegantly done although the equal length requirement means it's really tight in the engine bay now. There's a damn good reason why most header systems for vee motors, or long inline six engines, aren't equal length. The pipes just take up too much underhood real estate and are hard to manage.

It'll be dynoed to determine improvements, but out of the box one thing that is very noticeable is the sound. The motor sounds much smoother, crisper, with a higher pitched exhaust note. Greatly diminished is the rumpty rumble low pitch frequency exhaust noise that very much characterized the engine from the get go. It's not the kick ass sound of an inline six Z or BMW, but it closer to that and much more of a smoother wail at RPM.
 
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Besides the handling and exhaust, we’re still doing a lot of ECU tuning, particularly with modeling the mass air flow transfer function to fine tune fueling in all conditions. We’re also starting to play with individual cylinder spark timing for each cylinder, a la this excerpt from a presentation on optimizing engine power.

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In talking with Jeff G. he knows someone with experience in making the pressure measurements needed to figure out what the optimal timing is, and he's got access to the modified spark plug pressure sensors and data collection equipment. So we might try and make some measurements on the cars to see if there are any gains to be hand. Curiously enough the stock Ford EEC-V that we use to control the motor has individual cylinder trim spark timing, -5 to +5, with user definable RPM ranges these would take effect within and modify the commanded spark valve. That Ford built the functions into the ECU in the first place seems to indicate it might be needed for some certain applications, however our trim tables are all set to zero with no modifiers being used.

And in doing this work we've had numerous dyno sessions over the last couple of months. I think we've probably gone four times this year just to test ECU and tuning parameters. Fortunately we've got a great shop to work with where we can show up, strap down, and run the cars at generally $100 / hr. We always have our testing regime and files created ahead of time so we can get five or six tests done in that time. And we'll need to go back for the exhaust and maybe spark studies if we get that portion checked out enough to take a stab at it.

Work continues. There is always something to do.
 
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Been a long while since any updates but development has been continuing heavily over in the Stangwerks. Back in the May time frame we spent a lot of time at the dyno over two separate sessions. What we were trying to do was get the MAF transfer function to precisely fuel the car over the entire RPM range and pick up gains from our new exhausts. With A/F close doesn’t cut it because we do see differences when we’re off by 0.2 A/F ratio, and obviously as the difference becomes greater the power variation is higher.

Here is a plot from logged data in pulls through a couple of gears. As you can see the A/F drops a few tenths of a point over the RPM band. As the mixture gets richer the power tends to drop off and we end up with holes in the power band.

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Here’s a close up example of what I’m refering to, with an original and corrected power curve in a fairly narrow 800 RPM wide window. In this particular section of the curve, down in the 4k region, the original pull was deficient about four horsepower in this section. And, this wasn’t the only area of the curve affected as there were a few other areas that needed attention. When we can get the engine to run consistently at the target A/F of around 12.9 it is noticably sharper and pulls with more authority throughout the RPM band.

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The way we fix it is by re-mapping the MAF transfer function and shifting the limited number of cells for the curve to the RPM range of interest. As develiered the Ford ECU has most of the resolution of the curve focused in the 0-2500 RPM range and have very few points above that RPM. Furthermore, the Ford ECU V has adaptive learning so it starts to correct these values in the trasnfer function so that the operable RPM range becomes extremely well behaved.However, our operation is entirely different. We are only interested in WOT and the adaptive learning doesn’t not function at WOT, and, we don’t care about low RPM operation. What we do is use more cells/points in the 3000-5500 RPM range, thus allowing higher resolution there and more accuracy for delivered fuel.

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The ECU can still apply modifiers based on intake air temperature, coolant temperature, load, and a few other things that affect the ultimate fueling. And we’ve learned the hard way that these modifier tables themselves need doctoring because they can be too intrusive to the detriment of power, however, they can be completely shut off. Anyhow, the end result of the work was that we had two independent MAF transfer functions, one for each engine, that performed far better than what we had at the outset. At CMP and RA we had dead nuts accurate fueling that resulted in more horsepower area under the curve.

We still haven’t had time to get one of the cars down to the chassis tuning dyno but I hope we have time in September. Our new trilink in the rear is behaving wonderfully and we’d really like to see some hard numbers, measured instead of calculated, to go along with our efforts.
 
And more vibration analysis has been happening. This is from last weekend and fitting the chassis with three sensors as well as an RPM pickup to monitor the chassis, engine, and tranny throughout the RPM range.

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And gotta bust it up into multiple posts due to limit on pics. Anyhow, Jeff is still analyzing the data and looking for resonance effects from various vibrational modes.


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these have to be the two most developed cars in IT history. Truely inspiring, and intimidating, stuff ron and jeff.


unbelievable


what sort of go-faster-ness data come from the vibrational analysis.... Your way over my head!
 
Thanks but I'm sure lots of folks do some of this stuff, it's just people don't post about it. The vibrational analysis is Jeff G's forte. He's an engineer for a large company and that's his daily job, and, his Ph.D. is in vibrational analysis as well. Of course, that makes him extremely sensitive to vibrations but he's not been wrong about that aspect of the development.

Buried back up in the thread is the fact that the red car has a very odd, and sometimes extremely strong, vibration at certain RPMs. The green car does not have this problem, although it has a little vibration but not nearly the magnitude of the red car. We've done many experiments to rid ourselves of the problem: we've changed motor mounts, subframes, transmission mounts, two motors, one motor with a different balance percentage, transmissions, driveshafts, flywheel, pressure plate, pinon angle, u joints, axle shafts, tri-link, and axle housings. Still, the problem persists and the red car has broken three tailshaft housings while the green car has broken none.

We think we have a handle on it now though. We knew from Ford engineering papers that the 3.8 has a primary pitching moment fore-aft. With the measurements we think the moment can be particularly strong and believe the tailshaft became the weak link when the bellhousing would tag the chassis (clearance is extremely tight on the 3.8, about a pinky width at tightest point). So we're resolving some solutions to the problem and the green car will get them for good measure.
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For what it is worth, we now have a third Mustang build on the go and it's detailed on another forum. The car will be built to be IT-legal, but its primary, at least initially, purpose is LeChump so we decided not to build it here. That build thread will be more detailed than this thread since we're building even more items from scratch - panhard, trilink, perches, etc. will all be fabricated from steel by us to keep costs extremely low. On these stangs we paid over $1200 for a rear end setup we ended up only using half of, but with the new build we're spent $16 on steel to make the entire rear suspension, although with many more hours of work. Here is a link to the photo album with build pictures, although for narrative you'll have to go to the other forum.

https://www.facebook.com/Ron.Earp/media_set?set=a.10204370987184500.1073741830.1524789574&type=3
 
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EDIT:
For what it is worth, we now have a third Mustang build on the go and it's detailed on another forum. The car will be built to be IT-legal, but its primary, at least initially, purpose is LeChump so we decided not to build it here. That build thread will be more detailed than this thread since we're building even more items from scratch - panhard, trilink, perches, etc. will all be fabricated from steel by us to keep costs extremely low. On these stangs we paid over $1200 for a rear end setup we ended up only using half of, but with the new build we're spent $16 on steel to make the entire rear suspension, although with many more hours of work. Here is a link to the photo album with build pictures, although for narrative you'll have to go to the other forum


What is the "other forum"

Steve
 
Uh...it's like Fight Club I'm told. I can't link there.

Header piccy. We had the header off the other day for measurements so figure a picture would be worth putting up. Stainless steel, SS collectors as well, all properly sized. Version 3.0 but it was worth it for the midrange and top end gains.

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Steve35 said:

For what it is worth, we now have a third Mustang build on the go and it's detailed on another forum.

What is the "other forum"

Steve
Click to expand...

The third Mustang is very near completion lacking only graphics to be checked off.

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The ITS Mustang team did well this year being first and second in SARRC points, up until a week or so before the SIC where a FL based fellow took the lead. We didn't attend the SIC because we calculated that the chances of finishing enough spots in front of the leader for the series win, given the double points situation, wouldn't be possible.

The 2015 season at VIR kicked off with a bang with Jeff G losing his and me putting myself into the wall at T3 and earning a concussion to boot. We've got a lot of work to do.

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Quarter and wheelhouse OEM NOS search a problem? Doors and fenders should be EZ (maybe consider pre-painting spares).
 
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