SCCA STP autocross class power options

[ABQautoxer]

Hey guys,

I've been lurking this forum for awhile but couldn't really do much due to rules classing running in a basically catback only class. However next year the SCCA is running an experimental class called STP, or Street Touring Pony (car). It allows for an intake, header with cats, catback, and tune which includes upping the rev limiter. Emissions still have to pass. The intake cannot require cutting bodywork to install and the cat must be within 6" of the original location. With that in mind, I've tried to sift through the various reviews and thoughts but could use some experienced help on what gives the most. Also with regards to the rev limiter, we aren't raising it to make more power, we realize with those limit the car won't do that but it avoid shifting to third which makes it worth it. Ideally I'd like to do ~67mph in 2nd but with the 3.73 rear end which I'm not allowed to change by rules, that means reviing to 7900rpm so some compromises will be made there. Thanks in advance for the advice.

I prefer my car fairly quiet. I've had lots of very loud cars and I like my neighbors and driving 2000 mile trips without drone or pain these days. Currently I have just a resonator delete and wish it was a touch louder but not much so I am hoping the OE catback is not a restriction and I can just add headers/HFCs and probably get the increase I want.

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[Steid6G]

Subscribed,

Just started lurking myself. Currently running a 350z in STU and will be next year also. But the new STP class looks like it could be fun and the s550 is really giving me Mustang fever. Thanks for starting the STP thread. Hopefully, some good info can be compiled all in one place.

The easy solution in the Z was shorty headers and a high flow cat. Brian Peters and some others ended up having Long tube headers customized with the Cat sitting where the collector is. That did create some ground clearance issues if you drive your car a lot. Haven't seen much on the mustang Cat itself. Would a high flow cat help much? Again looks like a cut and weld only option.

I like your idea of the 3.73 gear and revving high. I guess the oil pump gears are the limiting factory when on that track?

I assume you have the PP on the car?

Scott
STU 196

 

[ABQautoxer]

My car is a PP. Looks like from those I've talked to the headers are low gains for us with the HFC still there. Intake seems to have a mixed bag of reviews. Tune we had to do anyway for the rev limiter. I'll probably do the rest later but in the initial build it doesn't seem a good bang for buck when we still need some good shocks, a rear spring solution, and wheels.

 

[Steid6G]

The rear spring bucket looks similar to the Z. If it's a 5 inch spring in back our solution was to use adapters from BC racing to convert over to a 2.5 spring. The adapters are available separately. Here is a thread with a couple of picks of the adapter. Maybe?

http://my350z.com/forum/autocross-road/600302-my-stu-build.html

 

[ABQautoxer]

I'll see if Dennis knows since he's rigged up stuff for this ESP car. I know Hardy is going to make something specific for the S550. I'm going to get them if I go to STP or not because it would allow for better lowering springs for street use if I go another route for autox and keep the s550 for daily use.

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