Drag gurus, come help my mph.

[lowflyn]

Car setup:
03 Cobra convertible
3.55 stock IRS with diff brace, forward torque brace, and solid diff bushings.
Stage V Eaton 2.76/2# made 490/490 on Dynojet corrected
315/45-16 ET street (27.4" tall) on 16x7 at 15lbs
215 width front tire on 17" wheel
Race weight with me in the car (220lbs) was #3968

TR6 plugs at .032
Gatorback belt replaced last track outing (4080775)

Here's my problem, quarter mile track wasn't open last year so I made several trips to a 1/8th mile track close to here, ended up with a best of 7.67 @ 97.19. 1.68 60', don't have a time slip for the other numbers. That was on the exact same setup around this same time of year.

Quarter mile track opened, and well...I've been disappointed.

Best pass thus far at 1/4 is:
1.859 60'
5.155 330'
7.866 1/8
91.64 MPH
10.155 1000'
12.119 1/4
114.68 MPH

Bad video of the run:
MOV01659.mp4 video by brudge75 - Photobucket

I know my time is low, that's driver error...why is my MPH so low for the HP and setup? What am I missing here to be in the 120 trap zone?

Also, current DR's are about done. Debating moving back down to a 26" tire, what benefits do you see in this change?

 

[fbody83]

Looking at your time slip numbers, a 1.85 60 foot isn't horrible and your shifting was good so I don't see any driver error here. When my car had a stage IV port it made 498/480 on a mustang dyno and I went 11.5 at 125 mph with a 1.8 60 foot.

How many times have you gotten the car dyno'd? Have you been to more than one? Who tuned the car?

 

[03 SeRpEnT]

yea mph is def off. Hell I ran an 11.80 @ 119 on a 2.8/4lb, no port.

 

[Tims97SVT]

39xx? Your car is fat! Loose some weight and it will pick up. Do you have the stock ic tank? Maybe your pulling timing up top.

 

[mustang john]

Are you cooling the car down between runs? I would also check the intercooler pump and see if its flowing, seen a few of those go out and cause a big drop in MPH. Your abour 8-10mph off where you should be.

 

[zeusha]

Are you cooling the car down between runs? I would also check the intercooler pump and see if its flowing, seen a few of those go out and cause a big drop in MPH. Your abour 8-10mph off where you should be.

:rockon: Seems like heat soak in the upper powerband, did you do the PPRV delete? could be getting some hesitation

 

[Red Turtle]

Hmmm, sounded like maybe some belt slip up top..? What was the D/A of the track the night of the run? What rpms were you shifting at?

edit: It also sounded like you crossed the traps at the top of 3rd or while shifting...? Seems as though you should have already been in 4th by the 1000ft mark.

 

[c6zhombre]

Hmmm, sounded like maybe some belt slip up top..? What was the D/A of the track the night of the run? What rpms were you shifting at?

edit: It also sounded like you crossed the traps at the top of 3rd or while shifting...? Seems as though you should have already been in 4th by the 1000ft mark.

+1

definitely sounded funny midway thru 2nd and into the 3rd gear shift. That probably screwed up typical shiftpoints/track position

 

[1320 Junkie]

114mph is = 400hp at your weight...something is off.

 

[lowflyn]

Looking at your time slip numbers, a 1.85 60 foot isn't horrible and your shifting was good so I don't see any driver error here. When my car had a stage IV port it made 498/480 on a mustang dyno and I went 11.5 at 125 mph with a 1.8 60 foot.

How many times have you gotten the car dyno'd? Have you been to more than one? Who tuned the car?

Car was tuned July '09 by Joe at dynospeed when I first put this setup on. Haven't changed anything on the car, and hasn't been back on a dyno since. Car made 404/368 stock pulley stock tune if that makes any difference.

39xx? Your car is fat! Loose some weight and it will pick up. Do you have the stock ic tank? Maybe your pulling timing up top.

Aftermarket IC tank, switch wired to pump and run entire time at track. Plenty of time between runs (30-45 minutes).

Also, that weight was with 3/4 tank of gas and me in the driver seat (215 lbs). Going to pull some weight this week and go from there.

Are you cooling the car down between runs? I would also check the intercooler pump and see if its flowing, seen a few of those go out and cause a big drop in MPH. Your abour 8-10mph off where you should be.

I know the i/c pump is working as it always has, no flow restriction or slow down.

:rockon: Seems like heat soak in the upper powerband, did you do the PPRV delete? could be getting some hesitation

No PPRV delete, stock pumps, upgraded FPDM, 60# injectors

Hmmm, sounded like maybe some belt slip up top..? What was the D/A of the track the night of the run? What rpms were you shifting at?

edit: It also sounded like you crossed the traps at the top of 3rd or while shifting...? Seems as though you should have already been in 4th by the 1000ft mark.

My first though was belt slip as well after thinking about it. Put a brand new belt on last trip out and ran same exact times...I have a non-slip billetflow upper pulley (one with cross hatches) and have never had a slip problem (very very little dust even after a track day).

My thoughts exactly on 3/4 shift, I feel like I'm crossing the line right on the verge of shifting, some passes it's top of 3rd (at fuel cut) other passes I have to hit 4th.

As far as my shift points..honestly I've never looked down to see. What should I be looking to shift at?

+1

definitely sounded funny midway thru 2nd and into the 3rd gear shift. That probably screwed up typical shiftpoints/track position

It sounded funny to me as well in the video, but I just put that to the location of the camera...all of my passes sound exactly the same.

114mph is = 400hp at your weight...something is off.

So please...help! lol

 

[96stanggt]

Did you datalog? Really can't tell you anything without datalog. The car is down 10mph, thats something serious.

 

[Red Turtle]

As far as my shift points..honestly I've never looked down to see. What should I be looking to shift at?

Start there. You are not getting in to 4th becase you are probably holding each gear to long. That may also be the reason for the funny sound on th 2-3 shift. It has been a long time, but I seem to think that I shifted at 6200-6300, and might have got into 4th just after 6000. Remember that 4th is 1:1 so it is ideal to get into that gear, and I don't know too many terminators that are crossing on the limiter in 3rd.

Do you have a dyno graph, and is what is your limiter set at?

 

[lowflyn]

I'm going to try and get the car back on a dyno in the next few weeks just to check. In the mean-time I'll be working on my shift points.

Crappy picture of my dyno sheet from having it tuned.

Not 100% sure on the limiter, will have to pull out the tuner and double check. I know it's north of 6500.

Also probably going to do a compression test for peace of mind before going anywhere in it again.