Lower Trap Speed

[99cobraUgotbit]

Last year I went to the track and ran a 11.8 @ 124 mph. NT05R tires. Mods in sig. 623/629 with stock elbow and stock TB. No LCA or brackets or clutch

I have recently added the VMP elbow and 67mm VMP tb. Clutch, BMR LCA with relo brackets. Went to the track last night with Hoosier QTP 28 x 11.5. I had a quarter tank of 101 octane and added 91 shell gas on the way to the drag strip. Not sure if the new crappy gas was a factor. Wasn't thinking.


Anyways. Here are the time slips:

..............6/14/14.........6/26/15
.............Last year.........Last night

60'..........1.849...........1.811
330'........5.231............5.225
1/8..........7.827...........7.995
MPH.........98.30............93.67
1000'.......10.044..........10.115

1/4...........11.877..........12.032

MPH........124.76...........118.45

The entire night I was having to shift into 4th between 10-15ft approximate before the trap. Never went night then 118mph. I can get better 60' with more practice. Regardless losing speed at high end

Any thoughts?

Side note. I did not take any brakes and that pass was my 4th of the night

 

[Mainn]

What was the DA like?

 

[99cobraUgotbit]

It was sundown 7:30ish pm. I didn't do a DA check. But maybe I can look it up

 

[99cobraUgotbit]

Da 2599

 

[heatsoaked12]

Sounds like a heat soak issue to me. Did you monitor any iat2 temps at all? I know that once my iat2 temps go up they will not go back down to a reasonable level unless I hit the highway.
Most people, including me, ice down their chargers between runs.

 

[99SSls1]

Datalog it asap don't run it no more. You have to be pulling gobs of timing.

 

[Blackmax]

Yes you were not thinking, get a tune for whatever gas and stick to it. Mixing gas is not a good idea especially Shell 91/

 

[99cobraUgotbit]

My tune is for 91 octane. Can't you put whatever in as long as it's 91 100% gas and up?

 

[Blackmax]

My tune is for 91 octane. Can't you put whatever in as long as it's 91 100% gas and up?

Nope, its not that simple. If you put in Shell 91 then bump it up with Shell 93 I would say no problem. With a regular street car you could pretty much do what you want as well, but with a supercharged car that has mods and is raced its a different story.

 

[99cobraUgotbit]

Nope, its not that simple. If you put in Shell 91 then bump it up with Shell 93 I would say no problem. With a regular street car you could pretty much do what you want as well, but with a supercharged car that has mods and is raced its a different story.

The 101 octane was pump gas


Hey BJ can you chime in please

 

[biminiLX]

You mentioned shifting into 4th before traps.
Did you cross in 3rd last year?
-J

 

[99SSls1]

Having too much octane can slow some cars down but I don't think it had anything to do with the problem here.

 

[99cobraUgotbit]

I looked at a video last year and shifting into 4th way earlier. 3.55 stock gear

 

[IronTerp]

Combination of high DA and its affect on combustion, and possible heat soak because of the generally high atmospheric temps associated with high DA, could easily cost you 6 to 7 MPH in the 1/4.

Personally, don't see a problem with the gas mixture's affect here.

Typically very difficult to get these cars to perform well when combining hot lapping with high atmospheric temps.

What are your shift points? Plus, Excessive spinning and/or being off the gas for slow shifting or squirreliness can push that shift into 4th way too deep into the run.

 

[99cobraUgotbit]

I assumed the HE would keep the temps in check. Should let it cool off a bit next time in between runs.

Need a gauge to keep tabs on temp, a/f, boost.

 

[builttodrive]

I didn't see if you disclosed this but what size were your nt05r tires? Could you have lost some gearing on the top end with a different size tire? I see you picked up your 60ft time slightly.

 

[builttodrive]

Looks like you had 305/35/19 in your sig. Which would be shorter but I'm guessing that made you shift in to 4th sooner and maybe the 4th gear ratio had you gaining more mph faster.

 

[IronTerp]

I assumed the HE would keep the temps in check. Should let it cool off a bit next time in between runs.

The HE will help, but using 80 degree air to cool down your engine/supercharger is only going to take you so far at the drag strip. Ice and time are your friends.

 

[99cobraUgotbit]

One more thing to ponder on. At times last year I was ranging between 124-126mph through the trap. Now I'm at 118mph. Keep in mind that I also added the Elbow and TB. Wouldn't that have added more HP to bump up the mph? If so, that's close to 10 mph loss due to possible heat soak?

 

[1320 Junkie]

Is your intercooler pump working and/or is the fluid flowing at the correct pressure ?

Reason I say this is because I had a kinked hose way back in 2012 when I was stock and my car was running 13's because of it lol. Fixed the hose and went 11.9