Project SRT-4 : Back on the road and tuning with the AFC


Project SRT-4 has been on a long hiatus, and after popping the headgasket late in 2008, we’ve finally gotten back around to getting this monster back on the street. Since it’s been a few weeks since our last update, let’s run through a quick recap.

Staying with the stock bottom end, we’ve chosen to run a Cometic head gasket for the SRT-4 along with ARP head studs to keep the 2 halves together.

Head is assembled, cams and cam caps torqued and assembly lube generously applied. Next, we torque down the head, following the SRT-4 tightening sequence.

Now onto the real challenge, installing and fabricating the downpipe, chargepipe and turbo kit on the back of this motor. What you are looking at is a 50mm Tial wastegate, DNP Turbo manifold and the back of the motor.

Project SRT cracked 350 whp on my Dynojet448x using a slightly upgraded stock turbo and stock fuel. Since then, we’ve stepped up to a 62-1 Garrett T3/T4 turbocharger in hopes of chasing down 440 whp on 91 octane.

Unfortunately, that also means ditching the stock manifold, turbo and downpipe, and if you’ve ever seen the SRT-4 Engine bay, you know how much of a bitch this is going to be.

After quite a bit of cursing and yelling, we’ve mounted and installed the turbo, manifold and wastegate, but our problem is still the dumptube.

Here’s a shot of under the car, looking at the back of the motor between the firewall and subframe. If you see the 2 power steering lines going into the rack there, that is about the only space we have to route a dumptube.

Time to get lucky.

Using a Vibrant V-band flange, we weld a 1.75 inch J pipe and completely hack up the bend to get the radius as tight as humanly possible.

After a lot of cutting and hacking, we’ve got a pipe that allows us to bolt it to the wastegate egress, but the bend is not tight enough to clear the power steering lines or alternator properly. Further, the opening is not large enough for us to cut and reweld, and instead of removing parts again, we’ve opted to heat up the pipe and bend as need be.

Unfortunately, we forget that the dump tube is 304 stainless.

It look a whole lot of heating and bending, but we finally got the screamer pipe to bolt on and clear all the lines properly.

A look at the finished product, note the clearance on the power steering lines as well as the clearance to the charge pipe coming off the turbo.

Now with that out of the way, we go to tune the SRT-4, only to find that the AFC NEO has a blank screen and refuses to turn on. This is a fairly common issue for these piggybacks as people love to yank and pull on the wiring loom, pulling the daughter board out of the AFC PCM.

To fix this issue, simply remove the hex bolts on the back of the AFC NEO and gently pull apart.

After plugging the harnesses back into the daughterboard, we snap the NEO back together and reinstall the hex bolts.

Your NEO may or may not go into DEMO mode, a mode in which the screen flashes and is not responsive to any button inputs. To solve this issue, turn the car off and then turn it back on while holding the UP button on your NEO.

This will force it into a diagnostic mode, where you must select to “reset” the NEO to gain control of it again.

After all the little BS issues are taken care of, we dial in the boost at a very low 10 psi and hit the streets with a datalogger to get some rough tuning out of the way.

Next up?

Dyno time for the SRT-4 as we chase 400hp on 91 octane.

Happy boosting!

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5 thoughts on “Project SRT-4 : Back on the road and tuning with the AFC

    • yep! big time PITA! was a super tight radius turn and there’s not much room to operate! lol.

      yeah the dump pipes are “for offroad use only” thankfully it will only open at WOT, so cops really don’t have much of a justifiable reason.

      • Interesting, I always thought they nab you with the visual inspection thing. There’s this mystique (or I guess more disdain) on the East Coast about CA and their “Smog Police.” Everyone’s always afraid to move there because their cars will get flagged during visual inspections because they check everything – lol

      • yeah CA really sucks for enthusiasts, although we’ve got all the shops and shows here.. odd how that works out.

        The screamer pipe isn’t something that easily seen ( or reached for that matter lol ) so I doubt the authorities will see it. Ive got some old school dump tubes to share with you once i can dig them up lol

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