HHR SS - The back-up car

[cornfedbill]

So, this will be the second year driving my son's HHR SS in the Sandhills Open Road Challenge because my Nova is till on jackstands.

It is not very sporty looking, but is quite capable. We have a tune in it from ZZ Performance in Grand Rapids. We replaced the MAP sensors and loaded the tune. We have tweaked it a bit and are pretty happy with the performance. It should be putting out about 300 hp and 340 lb-ft of torque at the crank.

It is a rare SS with the performance package, 5-speed, a rear seat and the panel rear windows.

We swapped out the rear sway bar for a 1" bar to reduce the understeer. It is very neutral now.

This year we are adding Firestone Firehawk Indy 500 tires on lighter wheels. We stuck with the factory tire size because we felt larger tires would reduce our acceleration because we are not very traction limited. We should be able to run full power from 3rd gear and up. Cornering with the stock tires was good. It will be better now.

This is us from last year.

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[cornfedbill]

So to bump up to the 105 mph class we need a roll bar. Every driver needs to run the 105 mph class in order to run in a faster class.

We have never built a roll bar before. Both my son and I are engineers by trade and seem to over-think things a bit. We studied the rules of the event, and rules and best practices from many other sources. We watched a lot of YouTube videos on roll bar and roll cage fabrication.

The biggest obstacle was strengthening the floor so the roll bar would not punch through. The need to be able to remove the bar (this is his daily driver and needs a back seat to transport the next generation of Harveys) also increased the level of difficulty.

We used 0.083" plate to cover the floor and to wrap up the vertical sections in the corner by the rocker and back seat. We formed the metal, welded it in and then built rocker boxes on top made of 7 gauge (3/16") steel. We capped it off with 1/4" plate with nuts welded to the underside.

Here are some photos of our work.

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By the time we got past this late Saturday night, we got too tired and focused to get more photos. I will get more tonight as I mount the main loop on top of the boxes and begin the cross braces and harness bar.
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[WallaceMFG]

Looks fun! I have an HHR SS as my daily driver, but it is an automatic so it lacks a few of the fun points that yours has. Mainly non upgraded brakes, no LSD (because of auto), and less power (also because of auto). I've contemplated getting a ZZP tune, but without an LSD I'm worried it won't be able to use the power effectively.

What sway bar did you put on the rear? I'd love less understeer in mine.

[cornfedbill]

The bar we installed is from Turbo Tech Racing. The HHR forums seemed to favor that one.

www.turbotechracing.com part number TTR100-1010. It made a big difference. We felt incredibly stable in the high speed turns.

The ZZP tune makes a big difference. We have it dialed back in first and second gears to limit wheel spin. You could do the same to compensate for a lack of LSD. But it would still be fun in third and fourth gears. Without some torque limiting in the tune while in first gear, we would have way too much wheel spin. The downside is the need to always use premium fuel. But that is a small price to pay for all the fun.

We hope to hit 150 mph in the mile shootout. It's very optimistic. We'll see. We were still accelerating hard at the end of the half mile last year at 116 mph. It's no rocket, but does well for only 2 liter and stock turbo, intercooler and exhaust.

[Bugzilla]

Bill - have you done anything to the oiling system? Different oil pan or Accusump? I dont know if its just my Ecotec or not but I have oil issues on hard right hand turns. The back of the head lacks oil drains big enough to keep the oil out of the head from what I have found. All the oil goes to the back of the head on right handers and just seems to stay there.

[cornfedbill]

Bill - have you done anything to the oiling system? Different oil pan or Accusump? I dont know if its just my Ecotec or not but I have oil issues on hard right hand turns. The back of the head lacks oil drains big enough to keep the oil out of the head from what I have found. All the oil goes to the back of the head on right handers and just seems to stay there.

No, we have not yet. Thanks for the tip.

However, since we are on a public road with a less-than-ideal surface, we try to keep cornering to no more than 0.7g. On a track we could push much harder.

It helps that we are trying to average only 105 mph this year. What we may lose in the corners, we can make up in the straights.

[cornfedbill]

More progress tonight.

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[cornfedbill]

One more photo. This photo is a bit better.

It sits 1/4" from the headliner and nearly touches the rear door panels. It fits pretty well. The B-pillars are hidden by the bar itself. The blue you can see is the open doors.

I need to fabricate the rear supports which will meet the top bar near the intersection of the crossbar. Then I need to add the harness bar. The harness bar will have to sit behind the main loop in order to make room for the seats. The factory seats are a bit fat and take up a lot of room.

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[Motoracer838]

So to bump up to the 105 mph class we need a roll bar. Every driver needs to run the 105 mph class in order to run in a faster class.
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"I've seen your welds, your getting a grinder for Christmas"... The welds that look decent are a bit cold, the others need more heat and less wire, the roll cage is a place where you don't take chances...

Joe

[cornfedbill]

We made it to Arnold, Nebraska, passed tech inspection, and ran the Loup 2 Loup and shootout. We will run the Sandhills Open Road Challenge in the morning.

I have photos and video to add. They will come.

We completed the car at 3:30 am Tuesday and were on the road by 7:30, drove to Nebraska from Michigan, slept, changed tires, registered and passed technical inspection. Then we headed to the road to practice. We have been having a blast here.