Proace4

Those of you with 1/2 mile experience. I have a few questions.

How do you calculate your possible mph/rpm for such an event? I am familiar with 1/4 calculators and have data to help me sort through information for that style of race. But given I have info from TI and some old info from 1/4 mile racing, I was hoping to gain some insight for 1/2 mile racing.

I chimed in the other day when a person was asking what they are capable of trapping. Now I am asking the same questions. Do you guys use any calculators or just wing it?

How many guys throw 5th in mn12 cars? I know it's not perferred or ideal, but I can't see it being possible to finish the race in 4th unless I drop to a 3.15 or even 2.73 rear gear.

3150# 1000-1100rwhp c5z current 3.42/28" tire

Thanks in advance!

Quickshift_C5

I don't think there is any way you'll finish in 4th unless you have a supercarged setup with a lot less power. I'm at 638rwhp and hit 5th easy and cross at 164mph, shifting at 7k rpm.

You might be able to use longer gearing to stay in 4th...but I guess I don't understand why you'd really want to. You'll gain a little by not shifting 1 gear, but I can't imagine that's worth the effort in a 1/2 Mile Event.

Proace4

My only reason for wanting to stay in 4th would be for transmission reliability. I would just shift slower and grab 5th if I need to, which I assume I will.

Smoove

You're going to be well into 5th for sure. Especially that power level. Surface/traction will matter on your overall trap speed. Track to track mph will be different unfortunately. Mimicking conditions DA is pretty uncommon. 180-190 mph probably my guess.

youngrigo

I make alittle over 600rwhp and trap 166 mph in the 1/2 mile. Ive done these half mile events 3 times...

I do have to shift into 5th at about 148-150 mph (6600 rpms on 26.4 inch tires) and 5th maxes out at about 179 ish

With a 7k RPM and 28inch tall tires id think you can get to about 170 ish mph in 4th

Cheesecake 07

I did 161mph last weekend at the NFZ in AZ. 27" tire, 4th gear bouncing off the limiter(6800).

I lost MPH every time I tried going into 5th, however I make a lot less power(560rwhp). Like above, I think 170mph is probably the limit in 4th with a 28" tire and a 7k limiter.

Good luck...sounds like a nasty car

LSOHOLIC

29.5"....ftw....

stevieturbo

Nobody in their right mind would still want to be in 4th at 1/2 mile distance.

BLOWNBLUEZ06

Time for a ZR1 transmission.

youngrigo

Im getting rid of my MN12 to build an MN6 and adding ZR1 5th and 6th gears...

Neil B

1/4 mile trap speed + 25 to 30 mph will get you in the ballpark. You'll definitely be in 5th with most rear gear ratios. Although, I hear that some folks are starting to use 2.56 rear gears and running through the traps in 4th.

Smoove

I have been preaching the use 2.73 gears in big power turbo cars for years. Everyone laughed, nobody listened lol. Kinda funny seeing someone else suggest this. Also makes roll racing very easy.... less shifts.

Proace4

I mentioned the possibility of swapping diffs for an event like this in my OP. I would rather stay out of 5th if I can, regardless of what frame of mind someone thinks I am in...

I would definitely consider it. Keeps the tires a lower profile possibly which could potentially help with handling and braking.

xtream1

Joel (JbVend) has done quite a few of them. PM him. IIRC, he's running a supercharged 850RWHP car that traps the 1/4 at 4th gear top of RPM. When he does the 1/2 mile he tops out 5th gear and 6th at the mile (I think he has a shorter 5th and 6th stack). It's just a reference point though.

JoeyG

WTF'ever, I listened. I like jb's setup with custom 5th and 6 gears.

Proace4

Seems to be the popular choice is to just grab 5th for a half mile.

Joey, what kind of mph do you have in a 1/2? and at the mile?

What transmission, rear ratio, and tire size?

Smoove

5th and 6th are sweet. Using the ZR1 6060 now myself. I do miss my stock mn6 and 2.73 gear on the street.

JoeyG

my old 416/125hp shot went 192-195mph in the mile. I only got one 1/2 mile slip and it was 16x-170? I was running an RPM stage 4 m6/3.42's/MT345/35/18. My twin setup went 164@1/2 186@mile on untested first outting. Going to MT 295/45/17 or my Toyo 335/30/18 R888 this may to finally get the 2 club in the mile.

D.Woods

Just posting to validate the rpm/speed reported above. My ~400 hp car will does the exact same. 178 was all it would do

C5 Scully

Subscribed!! I have a race over Easter down in South Africa... 3K stall 402 TF 235 102/102NM RPM level 7 auto 1000hp drivetrain 3.15 gears and 600-650 N/A with 250hp shot this time... cam 243/251 and shift rpm 6800..

It seemed I run out of power with 200 shot in 3rd and just revved... changed to 4 on auto setting early shifts and picked up some but seemed died and slow but speed was up by 10mph only but better...


Any help with shift points for my combo and power levels please and in the end isit just the same as a 1/4mile to you and the launch and just stay in it longer??? and complete the 1/2 mile?

I have done a coulpe but something is missing as I have double the power than before and ran the speed in the 1/4 that I did before on the 1/2 with the lesser power and stuck now...

Nitrous activation and cut-off also locked converter or loss for the 1/2 mile at WOT?

Thank you for the help!