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Topic: 1/4 mile pass advise (Read 2303 times) previous topic - next topic

1/4 mile pass advise

[video]http://s1194.photobucket.com/albums/aa373/tbirdsc/?action=view¤t=qtr_pass.mp4[/video]



1st and 2nd are good............3rd is    :barf:
The 2-3 drops to 3200-3300 rpm  traps 104mph on a 26" tire
5500rpm is peak power so a gear change might not do much.
Adding more boost earlier could help but this aod shifts too inconsistent.  A 5spd or 4r70w would be a better mod.
Thoughts anyone?
[SIGPIC][/SIGPIC]88 t-bird: 5.0ho, gt40y, crane 2031, fms 1.7, paxton@5#, aod wide ratio, tci stall, performer rpm upper, 70mm bbk, pro m 60, 42#s, 3.73 7.5" posi, jba shorties, borla, upr x. 13.4 @ 104mph. cbaza, moates, tuned by decipha

1/4 mile pass advise

Reply #1 –
All I know is that is sure sounds good!
'88 'bird, 10.9:1 306 w/TFS top end, forged rods/pistons, T-5 swap & bunch of other stuff, 1-family owned, had it since ‘98, 5.0tbrd88 on Instagram and YouTube

1/4 mile pass advise

Reply #2 –
Quote from: 50tbrd88;360806
All I know is that is sure sounds good!

Thanks, she's fun to drive as a daily beater, but would also like to go low 13's or upper 12's at the track. She'd be even more fun if the trans shifted as high on the 2-3 like the 1-2. Baumann transmissions said it's pretty much the nature of the beast with an aod. Silverfox trans says one of his valve bodies would help. 3.90's would probably be perfect and there are some 4.10's sitting in my garage. Problem is 4.10's may cause her to trap out of the power band, make 1st gear shorter and the 1-2 even higher?  The supercharger it might over rev. if overdriven and spun too high. More accurate control over the shift points would be ideal.  Just trying to brainstorm out loud and hope it doesn't sound like a rant of any kind.......it just seems like it's never enough powah........... :rollin:
[SIGPIC][/SIGPIC]88 t-bird: 5.0ho, gt40y, crane 2031, fms 1.7, paxton@5#, aod wide ratio, tci stall, performer rpm upper, 70mm bbk, pro m 60, 42#s, 3.73 7.5" posi, jba shorties, borla, upr x. 13.4 @ 104mph. cbaza, moates, tuned by decipha

1/4 mile pass advise

Reply #3 –
Have you thought about a manual valvebody?
Oh, 13.4 with a 7.5! I feel better about doing the HO swap now.
88 Cougar LS 5.0 .030 over, ported E7s with GT40 valves & trickflow springs, Proform roller rockers, HO cam, removed air silencer, K&N filter, smog pump delete, 2.25" dual flowmasters, Pacestter H-pipe & headers, HO computer, 65mm TB, Explorer intake, 19# injecters, 3.45s, rebuilt posi, and TCI shift kit.

1/4 mile pass advise

Reply #4 –
You're concerned with over spinning the blower? 

With a 4.10 and running 104 MPH, the RPM through the traps should only be 5,550 w/a 26" tire.  Running past power peak shouldn't be an issue.  I'd be surprised if the blower was pullied enough to be over spun under 6,000 RPM, but I know little of the old Paxtons...

When drag racing, a rule of thumb on shift points is 400-500 past power peak.  Though power falls off a bit at the upper RPM, it places the engine in it's power band in the next gear.  This allows the car to accelerate quicker.

This assumes the valve train is up to the task.

The power is there for 12.7's-12.8's with a 104 MPH trap speed.  To get there you need to drop the 60's. 

The torque converter locking in third gear hurts E.T.'s too (big RPM drop and no torque multiplication).  A non-locking converter can take care of that, but you loose cruise efficiency.

1/4 mile pass advise

Reply #5 –
Quote from: Bruce M;360829
Have you thought about a manual valvebody?
Oh, 13.4 with a 7.5! I feel better about doing the HO swap now.

yeah, even one with a transbrake, but the cost was pretty high and it's my daily driver. I will try to send my vb to Dan and let him work his aod magic :evilgrin:  :evilgrin:  :evilgrin:
The 4.10's are for an 8.8 rear, but the 7.5 has held up considering. It should be good for some time.
[SIGPIC][/SIGPIC]88 t-bird: 5.0ho, gt40y, crane 2031, fms 1.7, paxton@5#, aod wide ratio, tci stall, performer rpm upper, 70mm bbk, pro m 60, 42#s, 3.73 7.5" posi, jba shorties, borla, upr x. 13.4 @ 104mph. cbaza, moates, tuned by decipha

1/4 mile pass advise

Reply #6 –
Quote from: 86T-bird;360832
You're concerned with over spinning the blower? 

With a 4.10 and running 104 MPH, the RPM through the traps should only be 5,550 w/a 26" tire.  Running past power peak shouldn't be an issue.  I'd be surprised if the blower was pullied enough to be over spun under 6,000 RPM, but I know little of the old Paxtons...

When drag racing, a rule of thumb on shift points is 400-500 past power peak.  Though power falls off a bit at the upper RPM, it places the engine in it's power band in the next gear.  This allows the car to accelerate quicker.

This assumes the valve train is up to the task.

The power is there for 12.7's-12.8's with a 104 MPH trap speed.  To get there you need to drop the 60's. 

The torque converter locking in third gear hurts E.T.'s too (big RPM drop and no torque multiplication).  A non-locking converter can take care of that, but you loose cruise efficiency.

Funny thing you mention assuming the valve train is up to task. The heads have the svo gt40 valve train setup good for any letter cam. On the dyno sheet the peak power curve seems to flatten out and break up some before it drops hard. Some have said this is spark or inconsistent flow through the discharge but my gut feeling is valve springs. The rpm's on the graph are hard to read since the file was saved without rpm's being scaled. The dyno operator said it's not worth spinning her past 5500.  I can post it if you'd like to take a look. Boost actually spiked at the end of the run making look like overdriving the charger might get the boost in earlier. Btw thanks for the help :D
 Mike
[SIGPIC][/SIGPIC]88 t-bird: 5.0ho, gt40y, crane 2031, fms 1.7, paxton@5#, aod wide ratio, tci stall, performer rpm upper, 70mm bbk, pro m 60, 42#s, 3.73 7.5" posi, jba shorties, borla, upr x. 13.4 @ 104mph. cbaza, moates, tuned by decipha