Project Update for September 20, 2012: This build thread entry might seem a bit premature since we have two events coming up this weekend that I will have to cover in another update next week (GTA and SCCA). But there have been a lot of things happening with regards to our S197 Project that we felt it was time for another update. Some of you that follow Vorshlag on Facebook already know about a lot of this, but there's new information in here as well.
Getting 4th place in ESP was a great accomplishment considering the many concessions we have made to this car so that it can still be a nice street car, stay emissions legal, and do fairly well on a road course. This car really is a jack-of-all trades, running in all sorts of events, and we even drag race it a little. We ended up with a great street car with all of the creature comforts, but this has led to some weight gain and compromises that don't help the ESP autocross performance one bit. It's also my wife Amy's car and she refuses to let me cut on it. That means no wheel flares allowed, which has led to a lot of work to make the 18x12" wheels and 315s fit out back. There is no way to run any wider tires front or back without cutting the fenders, but I
do feel the car will be faster with more tire (every other tire size increase has always improved performance).
All that said about 4th place is great and all, but as a competitor I would much rather
win in the ESP autocross class. I know now that this is going to take a
dedicated autocross-only effort, like the cars in the first three places at Nationals this year, as well as many places below us in the finishing order. The air conditioning has to come out (weight), as does the radio and speakers (weight), and many cars are (cut and) flared to fit larger tires than we ran (315s are the small tire in grid - many ESP cars had 335mm rears). Others are also using the Update/Backdate rules to maximize performance.
Thinking, Planning, Scheming, Plotting...
What will it take? Like I said in my last post... less weight, more power, more tire. If we can maximize these three aspects and sort the handling, someone with my driving skills (or lack thereof) should be able to place higher than 4th. I can't buy driving talent, but I can build/tune/buy the rest!
After coming back from the 2012 SCCA Solo Nationals and weighing our car right off the trailer, I became fixated on lowering the weight on next year's ESP entry. At 3539 pounds, our red 2011 GT was 300-400 pounds overweight compared to the top 10 or so in the ESP class grid. That much weight is a massive deficit to overcome. JasonM and I stayed late several nights that next week doing research, weighing cars and parts, and just brain storming and bench racing ideas. Both of us have been autocrossing now for 25 years and we kind of knew that winning this class was going to take a serious, serious effort. We have had these discussions for the last 8 months, ever since we moved this car from STX (maximum of 265mm street tires) to ESP (unlimited width R compounds). With several National level events in 2012 under our belts, we had more data to work with and can better understand what we think it will take to win.
First day back from Nationals we borrowed and weighed a bone stock 2006 GT (thanks,
StuartM!) for comparison, and then found accurate weights on the 4.6 3V vs 5.0 4V motors and transmissions.
I posted about this on S197forum this week, and learned even more there. What we found out was the
Ford 4.6L 3V motor weighs almost the same as a new 5.0L 4V motor.
- 5.0 Coyote motor weight - Fully dressed (minus the A/C compressor) and filled with oil, the new engine weighs in at 430 pounds.
- Source: http://www.autoblog.com/2009/12/28/d...ll-new-5-0-v8/
- 5.0 Coyote motor weight - Shipping Weight 430 pounds, includes water pump
- Source: http://www.mustang50magazine.com/tec...ech_specs.html
- 2005 Mustang Spec PDF - 4.6L 3V MOD motor weight - 421lbs dressed engine weight (dry).
- Source: We found this on a Ford PDF, but the link no longer works. The FRPP catalog page for the old 2005 crate motor shows 435lbs dressed (see the S197forum post above for the page).
We will get a picture of the actual weight of the 5.0L from our 2013 GT when we pull it out over the winter.
Uh-oh, Spoiler Alert! Keep reading, heh. The Getrag MT-82 is also shown to be very similar in weight to the Tremec 3450, from what we can find online. Again, we will weigh the 2013's 6-speed Getrag transmission when it is out for a clutch/pressure plate/flywheel combination or out for the engine work.
This S197 drivetrain weight research was to see if we could take an early S197 Mustang (2005-2007 or so), swap in the 5.0L, keep the 5-spd, use the smaller, early brakes, and
maximize the update/backdate allowances of Street Prepared. We were hoping to find a magic 300 pounds somewhere just in the 5.0L motor and 2005 chassis swap, but this doesn't seem to be the case here. The SCCA's "UD/BD" rules are a little complicated if you come from outside the SCCA Solo world, but we understand them well. It allows racers to use "the best of the breed", usually putting engines and transmissions and major components from models within the same generation all together into one car. Nobody has built this "hybrid S197" yet, but it was discussed at length in the ESP grid and at the awards banquet at the 2012 Nationals. It has been on our short list all year for the 2013 ESP effort.
In the SCCA Appendix for ESP, all 2005-2013 Mustangs are "on the same line" for Street Prepared, so we can use some parts from the Mustang V6, GT parts from 2005-2010 or 2011-2013, Boss 302 and Leguna Seca parts (that's why it's legal to use the LS front splitter), and even GT500 parts (not that we would put the heavy, heavy supercharged V8 from that car into a lightweight ESP car; we already make plenty of power at 430 whp). As long as it is swapped as a complete component (like a complete engine - it's all detailed in the rules) and no cutting/drilling/welding is needed, then it is a legal swap in Street Prepared.
This UD/BD rule allows us to potentially make a lighter, more powerful S197 than anyone has done in the E Street Prepared class before. We were competitive in the 3540 pound car, but how would we do in a 3100 pound version making the same power and on the same tires? The first place ESP car is one of these "hybrid" builds with a Corvette-based motor from a 1992 Firehawk, a transmission from a 5.0L 5-speed Firebird, all in a 1988 Firebird shell. There's a bunch of these UD/BD builds in Street Prepared that have all the best parts from one generation, making a car that was "never really offered", but that uses factory drivetrain combinations that are unique.
Stuart's stock 2006 Mustang GT 5-speed with minimal fuel load weighed 3442 lbs. Of course we took the trunk junk out for that weight.
As you can see, this 2006 GT weighs 3442 with no trunk junk and low fuel. That is a 121 pounds lighter than our 2011 GT was when it was bone stock (3563 lbs, no trunk junk, same minimal fuel load) and 97 pounds lighter than our car was in ESP form at the 2012 Nationals (3539 lbs). The questions is - where does this ~100 pound weight difference come from?
Size and weight specs on the three main front disc brakes for the S197 Mustang GT: 12.43" diameter, 13.22" front, and 13.96" (Brembo).
We think this weight differential is from a few sources, including the smaller front brakes (12.4" fronts vs Brembo 14"), 2-piston vs 4-piston calipers, a
theoretically lighter insulation package, and some other bits that we will confirm as we go. After making spread sheets and doing multiple builds on paper with an early car and the late motor, it looked like a total nightmare - and
offered almost no weight or cost savings over starting with a 2011-2013 5.0 GT. JasonM here at Vorshlag said it best, in a discussion on 'carvers...
continued below