Still can't get into the 12s.

[gmantheman]

Went to Fontana for street legal drags. 5 of my passes were P.B but the weather and D/A played a huge roll. I also added an aluminum d/s, replaced the M&H 275/50/17 (28") with M/T 26.5x11.5x17 (25.7") tires and had dyno tune. My previous best with a D/A of 3075' was
60' 1.843
1/8 8.595 at 80.23
1/4 13.376 at 103.99

Today's best with a D/A of 1290 was
60' 1.806
1/8 8.436 at 82.05
1/4 13.185 at 102.87.

I wonder if the shorter tire is hurting my time a little. With the M&H I trap in 3rd at 6500 RPMS. With the M/T I have to shift to fourth and I trap right around 5000 RPMS.
Here is one of my runs against an 2006 Pontiac GTO.


This was my first run of the day.

 

[Boss281]

You have the 60 and a fair trap speed. What rpm are you shifting? Are you speed shifting (gas always to the floor)? Just a guess since you don't have video but I'm wondering if you need to get the shifts quicker and a bit higher in the rpm band...I have the same MTs...

 

[06gtmustang]

wow something is up.I trap at 105-106 with less mods and 5000+ da. When i changed my stock plugs for some ht1's it picked up my mph some plus i have 4.10's and run 275/40/17 bfg's and i trap in fourth gear about 5800 rpm and this is with a 1.8 sixty too. Now i have more weight reduction and a couple more mods so goodbye 13.034 at 105.99.

 

[gmantheman]

You have the 60 and a fair trap speed. What rpm are you shifting? Are you speed shifting (gas always to the floor)? Just a guess since you don't have video but I'm wondering if you need to get the shifts quicker and a bit higher in the rpm band...I have the same MTs...

I am not speed shifting, but I think my shifts are fairly quick, the CHE-K member w/tq limiters helps with the shifting. I am shifting right around 6500.

 

[gmantheman]

wow something is up.I trap at 105-106 with less mods and 5000+ da. When i changed my stock plugs for some ht1's it picked up my mph some plus i have 4.10's and run 275/40/17 bfg's and i trap in fourth gear about 5800 rpm and this is with a 1.8 sixty too. Now i have more weight reduction and a couple more mods so goodbye 13.034 at 105.99.

I am not sure if there is something wrong. I also have 4.10s and I did replace my sparkplugs at 45,000 miles or so. I have 87,000 miles on the car now.

 

[fdjizm]

Hmm you should be trapping higher with those mods for sure even with that DA

 

[gmantheman]

Do you think I should have shifted into 4th sooner than 6500? That way I could have driven in 4th a little longer?

 

[06silverbullet]

Do you think I should have shifted into 4th sooner than 6500? That way I could have driven in 4th a little longer?

do you have a dyno sheet of your car, if you're not making power at over 6k rpms there's no point in going that high. a aftermarket manifold would help make power in the higher rpms so you could rev the piss out of it and still continue to make power.

 

[2006BlackGT]

Do you think I should have shifted into 4th sooner than 6500? That way I could have driven in 4th a little longer?

You need to speed shift.

 

[gmantheman]

do you have a dyno sheet of your car, if you're not making power at over 6k rpms there's no point in going that high. a aftermarket manifold would help make power in the higher rpms so you could rev the piss out of it and still continue to make power.

According to the dyno, my peak hp is just over 6200. I believe the general rule of thumb is to shift right around 500 RPMS above peak hp.

 

[VTXFrank]

According to the dyno, my peak hp is just over 6200. I believe the general rule of thumb is to shift right around 500 RPMS above peak hp.

Hell, I shift right after peak. If peak is 6500, I'm shifting at 6600. Going over more than that isn't doing you any favors unless it's to remove one shift from the 1/4. But even then, if you aren't powershifting the fuck out of it, and I don't want my tranny to shit parts, so I don't power shift either, I would still try shifting at 100 above peak and if it takes you that extra shift, maybe shortshift it at 6400 and see what that does for you.

 

[gmantheman]

Hell, I shift right after peak. If peak is 6500, I'm shifting at 6600. Going over more than that isn't doing you any favors unless it's to remove one shift from the 1/4. But even then, if you aren't powershifting the fuck out of it, and I don't want my tranny to shit parts, so I don't power shift either, I would still try shifting at 100 above peak and if it takes you that extra shift, maybe shortshift it at 6400 and see what that does for you.

Next time out I see what shifting at 6200-6300 does. I was thinking since I had cams and delete plates, I could rev a little higher.

 

[fdjizm]

do you have a dyno sheet of your car, if you're not making power at over 6k rpms there's no point in going that high. a aftermarket manifold would help make power in the higher rpms so you could rev the piss out of it and still continue to make power.

this myth is everywhere.

 

[killr3v]

this myth is everywhere.

Lol I think I have seen you post the chart like 5 times and people still don't get it.

 

[KungFuHamster]

i think youre down on power. i went 103 with just a CAI. and you may need to bang those gears a little harder.

 

[gmantheman]

i think youre down on power. i went 103 with just a CAI. and you may need to bang those gears a little harder.

I think there are few factors there. MPH can be inflated a little if you are spinning as your E.T will decrease but your MPH will increase. Also, bias ply tires which M/T E.T streets are, will give you a little slower MPH, or that is what I was told.

 

[gmantheman]

Video added. Thanks to Zuritausmc (Robbie)

 

[cantdrive55]

I think Fontana just sucks. It seems everyone was running a bit slow, and trapping a bit low.

 

[wbt]

Second vid where you can hear the shifts...they sound a little slow. Do you have a short throw shifter?

 

[Daniel Day]

Second vid where you can hear the shifts...they sound a little slow. Do you have a short throw shifter?

^^^ +1