Autocross; so what Mustang is best suited for it?

[TeeLew]

@TeeLew equal prep

Equal prep and driver, Let's say PP1 car vs. an Eco HPP...I'm going to give the V8 it's due. It will be a tick quicker in an AutoX and as the track gets longer, it gets a bigger advantage. Yes, the weight matters for handling, but we call it motor racing for a reason. If I'm giving away 120 HP and 60 lbft of torque. It's hard to discount that. I could crow about beating GT's and Camaros when my engine was still stock, but the honest truth is that I just have a lot more experience than the guys who were in those cars.

For $1500 bucks, I get an intercooler, a custom tune and a few bits and bobs. Now I've picked up 80 HP and 100 lbft over stock. You're still going to outrun me on a long track, but now you're going to have your hands full in a parking lot. If we both have the same tires and suspension and there isn't a massive power discrepancy, then it just comes down to physics.

When the new engine goes in, it's probably going to be another 30# lighter on the nose between a little sportier clutch/flywheel combo (the stock one won't hold the torque) and the countershaft delete. The BMR K-member goes in at the same time, so there's some more.

There are a few variables on a car which are completely fundamental to how the car handles:

1. Wheelbase
2. Track
3. Tires
4. CG height/Weight distribution
5. Aero (if that type of car)

Everything else is decoration.

Sponsored

 

[TeeLew]

Look at the direction change ability this thing has in those slaloms. Being a '12, this car is *really* light, but you just don't get that with a V8 on the nose.

 

[TeeLew]

I think this is a pretty good track comparison of the two. The track is bigger than an autocross, but smaller than a true road course. The guy does a pretty damned good job driving, so I don't think there's much to complain about there either way. He runs a bunch of laps in both cars before actually driving the real lap. With the stock intercooler, he would be running air-frying intake temps, so power would have been well off the advertised numbers. The GT is a hell of a lot more durable in that regard, no question (you overheat the diff quicker, lol!). There was a difference in tires, so maybe that was worth 1/2 second, but regardless, the GT has a clear advantage.

 

[Firsttexan]

I have heard auto crossers are using the F150 Coyote intake for more low end torque. I guess they are using the cams too.

Is this true?

 

[shogun32]

The F150 intake/cams does move the powerband, yes. aka True. Whether or not people are making class-(il)legal mods to their motor, I have no idea.

 

[NightmareMoon]

I have heard auto crossers are using the F150 Coyote intake for more low end torque. I guess they are using the cams too.

Is this true?

I’m not aware of anyone at the top doing that. Its possible theres a guy, but its not a common path, and FWIW my car has a ported 18+ intake and its been the fastest S550 at nationals for the last couple years. I’d say fastest mustang but in ‘22 a kid in a CAMT Fox body had a better raw time.

I get my power on top, like god intended. The car has plenty of torque to come out of a most autocross corners. Thait said, a little more torque and 200 more horsepower would be fun to try to control.

 

[Bluemustang]

The one thats modded for autocross and the class you are driving in.

 

[TeeLew]

I get my power on top, like god intended. The car has plenty of torque to come out of a most autocross corners. That said, a little more torque and 200 more horsepower would be fun to try to control.

You end up doing a lot of big track, stuff, right? A buddy of mine has a Whipple that gives him what you're talking about. It handles real nice down the straights.

 

[mavisky]

When I'm daydreaming about autocross cars and setups, one of the things I look at his "How fast can it go in 2nd gear?" I don't mind shifting in mid-corner once in a while, but there's such a thing as too much.
I've had days when I had to shift up to 3rd gear, and it's only a few seconds before I need 2nd again.

My 2020 GT-PP1 is good for about 78mph in 2nd, which covers the vast majority of autocross courses.

The Mach 1, with Tremec, has shorter gear ratios in the transmission. The numbers look favorable for acceleration but then 2nd gear is only good to 70mph. It depends on your local club and site whether you needed 3rd.

A 2015-2017 GT-PP would have to shift to 3rd by 64mph, and I reckon the car is fast enough to make that shift mandatory for most courses. The car would be geared even shorter if you put 305/30R-19s on it.

This was one of my issues with the 305/30-19's and the Tremec in the GT350. On small courses Im out of the power band by a bit and working into it, but on longer courses I've run out of gear in 2nd before. Actually had the rev limiter raised to 9,000rpm for the few instances where I want to try and avoid a 2-3 shift just to brake and go back to second again.

Ran into that exact scenario at this Porsche event before getting the tune done on the car.

 

[TRDFurgesson]

I autocross my Mach and Im gonna say EcoBoost. Just gotta get past it sounding like a riding lawnmower.

 

[TeeLew]

Just gotta get past it sounding like a riding lawnmower.

It's easier to get rid of herpes.

 

[2morrow]

Autocross encompasses several different classes. I would look at the locations, classes and area of track that you're going to auto-X.

If you are going to CAM-C or something of the like then GT for sure.

However in my experience with private club auto-X and some of the venues around me, the mustang platform was too big. A smaller, more nimble car typically benefitted. If american car was desired, a stripped down corvette would be best and with that being said, 3rd gear was hardly ever used.

 

[WildHorse]

EcoBoost weight distribution : 52/48 front-to-rear
GT weight distribution : 53/47 front-to-rear

Yer giving that 1% advantage too much credit.

460 vs 306 horsepower power to weight ratio heavily favors the GT

It's the driver.

 

[TeeLew]

That GT number is a little optimistic. It's closer to 55% front weight on the GT. The Eco is about 2% less front weight and 175# less overall. It matters quite a bit in terms of handling and balance, but the GT is still faster stock because it's got a lot more power. That's an issue which is not all that difficult to address.

 

[Hack]

I'm not an autocross person, but I have run a couple times. I didn't really like how small a percentage of time is actual driving. The events I've been at were less than 10 minutes of driving in a 6-7 hour long event. Drove me absolutely crazy. HPDE road course events are more expensive, but you get enough driving to wear you out.

I would say if you are thinking about doing autocross, definitely start by just attending some events before you spend any money modifying your car for it.

I have driven really small, light, underpowered cars and Mustangs including my GT350 in autocross. Both are a lot of fun (when you are driving - both suck when you are sitting for hours waiting for another 1.5 minute run). I think if your goal is to win locally, you should find out which local classes have really good drivers in them and avoid that class. If you are just driving for fun it doesn't matter what car you choose. Just run what you brung.

EB/GT/GT350 or 500? I think the best one is the one you enjoy driving the most.

Sponsored