Does a full exhaust make a difference? You decide.

UNBROKEN · Dec 2, 2020

ZFG 93 tune, Whipple IC and drop in air filter...added SPD downpipes and full 3” exhaust...best 1/4 before was a 12.24 iirc. This was with no adjustment to the tune and launching at 2700 so the 60’ was a bit slower than my best 1.74.
We’re fine tuning the 93 tune now but I’m waiting on dry roads again. I believe this is the quickest 93 tune pass anyone has made to date.

dolsen · Dec 2, 2020

That’s a really good DA too. What was the DA on your previous run?

Is that 60 ft of 1.74 vs 1.78 a big difference? I know that a decrease in 60 ft is supposedly equal to two times the decrease on a 1/4 mile time, but on an unprepped road it would seem .04 seconds is within a standard margin of error.

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UNBROKEN · Dec 2, 2020

The 12.24 was also in good air and negative DA.
Picking up over a 10th with no tuning changes is solid. We’re gunning for an 11.99 on 93 though.

F=MA · Dec 2, 2020

For a 4700 lb car it looks like it makes about 12 hp difference using the 1/10 gain in ET and the following simplistic equations:

https://www.gregraven.org/hotwater/calculators/hp-from-qm.html

UNBROKEN · Dec 2, 2020

F=MA said:

Actual weight on one dressed like mine is right at 5000lbs. That would put it at 16hp...keep in mind that’s the same tune as before the exhaust. We’re working on the post DP/exhaust tuning now trying to crack into the 11’s. An 11.99 would show a 30+ hp gain...we’ll see what happens.

F=MA · Dec 2, 2020

That is true one has to add the driver dead load. In the old days one could shave a tenth for every 100 lbs of weight removed. You need to start removing the seats

So why are you still using a 93 tune instead of an E50 tune?

UNBROKEN · Dec 2, 2020

F=MA said:

I wanted to have the exhaust done before switching to corn...but now we’re curious to see if we can tag an 11 on 93. And I won’t pull anything to do it. It’ll either make the number or it won’t but if it does it’ll be at full weight.

dolsen · Dec 3, 2020

In your opinion, do you believe the gains are from the downpipes, the 3" exhaust, or maybe a combination of the two?

UNBROKEN · Dec 3, 2020

dolsen said:

I personally don’t think the DP’s feeding into a stock sized exhaust has as much potential.

DoingOK · Dec 3, 2020

You gotta duct tape the roof rack rails and missing driver door lock back on for full weight....lol

I know you went with 3" stainless.....do you think the exhaust saved you some weight or was it a wash? On a serious note, that's pretty impressive numbers.

dolsen · Dec 3, 2020

Good job brother, I'm asking questions because I'm curious, I am not trying to take away from the speed/times

UNBROKEN · Dec 3, 2020

DoingOK said:

I think it’s close to a wash on weight. The oem exhaust was surprisingly heavy. I thought I’d be adding weight for sure but now I’m not so sure. It’s all a guess though...I didn’t actually weigh anything.

Kruppa · Dec 3, 2020

Awesome to hear - I'm dropping off the beast soon for custom 3" downpipes all the way back. Same other performance mods as you including 93 ZFG tune. It's hard because the roads are so damn cold and stock tires aren't super grippy but I've been running closer to 2 second 60ft and 12.5 ish 1/4 mile. My launch isn't down yet for sure I need to get better at it. I also get quite a bit of wheel spin going into 2nd and 3rd - some may be tires/temperature but debating turning down torque in 1st gear.

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