New worst at track

[Grabber Blue 5.0]

No slicks. Car shouldn't need slicks at 380rwhp.

I would agree with this.

 

[555]

Maybe time for slicks? I also agree that the gear swap isn't helping you. You don't have the torque to make the 3.31's work like they should. I know you disagree with that, so I'll let you figure that one out over the next few track outings.

Once you get it to hook again, you're going to find that it's just not accelerating like it did with the 3.73's. The balance between hook and bog is hard to find with tall gears, and an n/a motor.

Thank You!!!!!

 

[2011/5.0]

Before i lowered my 11 i dropped some cj rear springs in and it improved my launch % I run the crappy torque less .331 gear with a 4c 28 rear and 28 skinney i was going 11.8 on that set na. My 373 and 410 are at the bottom of the river

 

[psfracer]

Are you sure the DA was the same?

What is eye opening to me is your previous outing was 115mph. Now its 110, 105, 110, and 108. Thats a serious drop off in mph and power.

 

[2011/5.0]

I believe he never hooked up. I spent a year going through this and theres different answers for different tracks we have very poor prep so thats why im setup the way i am. If we had great prep a boss intake and 410 would be on my list but their not

 

[psfracer]

But usually if you spin, your mph actually increase 1 or 2 (because your wheel speed is up). Often when you cut a really good 60' vs your normal 60', your ET will be quicker, and sometimes your mph will actually be less.

Anyway...just saying to go from 115 to 108, 110, is a lot.

 

[Unreal]

DA was a bit higher, but it was traction issues. It wasn't just spinning off the line, it would spin all through 1st. Then 1/2 the time because of wheel speed it would shift 1st to 3rd (dumb autos) then bog down, figure out it should be in 2nd, and downshift. There wasn't a single clean pass so I wouldn't use trap speed as an indicator of much.

28" tire is on the list, in fact I got some 325 15" et streets that just showed up for the vette. If they don't work on the vette then I can throw them on the mustang. For now the 255 16s will have to work.

The one slow run (14.0@105) I left it in 2nd after the burnout and it rode the limiter until I figured what was going on, so that was embarassing. A new 2014 vette beat me that run only because of that.

I will say, I had the quickest late model mustang at the track. Everyone else was 13.5s and up. Even a new TVS roush stage 3 was only going 13.5s.

 

[psfracer]

Wow that track sounds absolutely horrible.

 

[Unreal]

It was. Everyone was a good 1 second or more off their normal times. Even the GTR that was running was only doing 10.8@140 compared to 9.8@146-147. Lesson learned is maybe only go during the events where they prep it. The test and tune nights are useless unless you are running a 150hp Honda.

 

[07 Boss]

I'm confused, you went from stock gears to the 3.73's, or did you switch back from 3.73's to stock gears (3.31's)? Switching to the higher gear ratio, or lower gear, should allow you to get more of the area under the curve to the ground during the course of the 1/4 mile. It may take a little more throttle control to get it there but the more power you get to the ground will make you faster. Track prep and suspension/tires make a difference too. For the one that said it's an automatic and all you have to do is hold the gas, well that is not really true. I find it rather tricky some days to pull as decent 60' because I have to roll into the throttle. You can't just mash it to the floor and go, doesnt work like that. Too much too soon will cause wheel spin, too little too late makes for poor times.

My times can vary .9 depending on DA, track prep, and how well I can adjust my throttle input. that is going to be key. The 3.73 geears will allow you get more power to the ground if you can harness it. You have to learn how to pedal the car on crappy days to avoid excessive wheel spin. Sounds like you just mash it to the floor by your descrition of going from 1st to 3rd due to wheel spin. My car has never done that. That kind of sounds like a tuning issue.

 

[Unreal]

Went from 3.15 to 3.73 back to 3.31. The 3.73s just add an extra shift and any additional power under the curve is lost in the extra shift. 3.31s go through the traps in 3rd without shifting to 4th at the 1100ft mark.

 

[Grabber Blue 5.0]

The 3.73s just add an extra shift and any additional power under the curve is lost in the extra shift. 3.31s go through the traps in 3rd without shifting to 4th at the 1100ft mark.

Why is it so difficult for people to understand this?

 

[Unreal]

Yah, the last 200ft at 4500 or whatever isn't make the power under the curve better. Finishing mid gear isn't good.

 

[07 Boss]

Why is it so difficult for people to understand this?

Yah, the last 200ft at 4500 or whatever isn't make the power under the curve better. Finishing mid gear isn't good.

No, I understand, but I would have gone the other way. I would have gone to a shorter gear to be farther along in 4th at the end of 1320. If I were planning to keep my current power level I would switch to 4.56 gears so I could be well past 6K rpms in fourth Currently I cross the line at about 5750 rpms.

A lot has to do with the individual car. I have a really flat torque curve. If you have a power curve that drops off pretty steeply it may be more beneficial to actually shift it before the finish. How much you lose during the shift vs the difference in power at the shift points is what is critical for this decision. For some it will be more beneficial to stay in third and others it may be more beneficial to shift into a higher gear. Especially in an automatic where there is not that much lost in the shift.

Tranny gear ratios make a big difference too. My tranny would top out around 105 in 3rd with 3.31's. My trap speed is about 118 with my 4.10s. So tell me how trapping 10 mph slower is going to be quicker than where I am at currently.

 

[2011/5.0]

My 4v traps at almost 118 in 3rd with .331 but thats a 11.50 et

 

[Five Oh Brian]

Went from 3.15 to 3.73 back to 3.31. The 3.73s just add an extra shift and any additional power under the curve is lost in the extra shift. 3.31s go through the traps in 3rd without shifting to 4th at the 1100ft mark.

And so what if there's an extra shift? It's an automatic transmission, and with a proper tune that shift takes a millisecond and doesn't hurt the car at all. And, with a big stall converter, the rpm's stay right up there in the power curve, so no power is lost.

In a manual transmission, that extra shift would be a problem, but in an automatic, it's negligible. 4.10's and a 28" tall drag radial in my '14 GT auto use nearly all of 4th gear in the 1/4 mile and it upshifts to 5th gear just after the traps - absolutely perfect in my opinion.

 

[2011/5.0]

I would have went 410 if my track would hold that on the launch. I would prefer the 410 for in town 331 is a little boggy in town as the auto seems to upshift early

 

[07 Boss]

And so what if there's an extra shift? It's an automatic transmission, and with a proper tune that shift takes a millisecond and doesn't hurt the car at all. And, with a big stall converter, the rpm's stay right up there in the power curve, so no power is lost.

In a manual transmission, that extra shift would be a problem, but in an automatic, it's negligible. 4.10's and a 28" tall drag radial in my '14 GT auto use nearly all of 4th gear in the 1/4 mile and it upshifts to 5th gear just after the traps - absolutely perfect in my opinion.

Yep, when building cars I have found the fastest times I can get out of them is when your topped out in 4th at the end of the 1/4 mile. I don't see the advantage to topping out in 3rd unless you maybe have a steep and narrow power band or a 3-speed tranny.

And when I meant area under the curve, I mean mathmatically, if you take the area under the curve from lets say 4500-7000 in 1st to 3rd from your dynograph, it covers a certain area. If you add the area from 4500-5000 from 4th gear, it covers a greater area. The area being a representation of the power your motor makes. That is what I mean by area under the curve. The more of the graph you can get in before the finish line, the faster you're gonna be. Granted if you can get that power to the ground.

 

[07 Boss]

I would have went 410 if my track would hold that on the launch. I would prefer the 410 for in town 331 is a little boggy in town as the auto seems to upshift early

Have someone tune it. You can change all your shift points either using RPM's or MPH. Or if they are good they can get it to shift higher based on the tables using torque load and throttle position. My car never shifts below 3000 RPM's and even higher when I'm on the gas. Basically at zero throttle position my car will upshift at 15 mph increments. The shift points go up with the throttle position.

1st - 2nd @ 15 mph
2nd - 3rd @ 30 mph
3rd - 4th @ 45 mph

And I shift into 5th manually at about 65-70 mph.

 

[Unreal]

The extra shift puts it in a crappy part of 4th. If it had 4.10s or something to max out 4th that is great, but being at 4k for a few hundred feet just bogs it down in 4th. Now if it was wrapping 4th out, that is fine, the extra shift isn't a deal, but not accelerating for the last 200ft is.

With traction already an issues, 4.10s would make it worse, plus the 3.73s were bad enough for mileage and hooking on the street. The 3.31s are perfect for trapping 117-119mph at the top of 3rd.