3.73 Kill top end!!!!

[GreenMachine]

I just got the lsd and 3.73 installed, broke them in, and I went racing. My best run of the freaken night was a 16.0 :mad: . Here it is in detail

r/t .180
60 2.129
330 6.655
1/8 10.194
1000 13.355
1/4 16.022
mph 83.70

I ran that all night [img]redface.gif[/img]
Here is the comparison to my best run with the open diffy and 3.23s

R/T .309
60' 2.304
1/8 10.122
MPH 68.64
1/4 15.739
MPH 87.58
As we can see after getting the 3.73s, my top end suffered greatly while my 60 foot was pretty good.
Is this common to lose this much mph for the 1/4? I will tell you this, I was shifting into 4th gear. Maybe I should have left it in 3rd gear, but I felt like i was losing power. My CAM goes weak around 5000+ (I do have a small CAM, wish I went bigger).

So their it is, a very sucky night. I gotta get a tune up wait for the weather to drop a few more degrees here in Florida. Maybe then I will get sub 15.5s.

[FbodTrek]

hmmm.....That's interesting. Well, I'll say this much, higher (numeric) gears are almost ALWAYS gonna cost you top end. A 3.4 (even a cammed one usually) makes its power in the midrange, not up high. So 3.73's are just about too much gearing. With a 5 spd especially (they have shorter gearsets than the auto's). A 3.42 would be fairly well matched for a 5spd 3.4 car. It appears that you spuna bit as well, you should be able to get 2.0 60ft's without a problem with those 3.73's (I get 2.08 with my 3.4 3.42's open, Auto). What cam do you have? If it's like mine, you are going to feel the torque drop off high in the rpms anyway, but don't think you aren't making power (you don't feel horsepower). I dunno.

[navyblue2000]

wow, 87 mph is pretty impressive for a 3.4L... what is done to it?

Perhaps yes, a cam to make more top end will help.

you have a manual trans. how's the 3-4 shift for you now?
that might cost you time too.

[Camarorulz]

Switch those out for 3.42s, then you'll see better top end. The 3.8 is not a top end engine at ALL, and the 3.4 is worse, a cam that gives you more top end power would definitely help, because that 3.4 doesn't lack in low end or mid-range.

[OneQuickV6]

Different nights, so it'd be kind of rough for you to say that was just because of the 3.73's! If your trap only suffered, then I could see it, but to lose ET from lower gears.... I would be willing to bet that the dnsity altitude when you ran the 3.73's was worse than when you ran the old times!!

[99v6cam]

Originally posted by Camarorulz:
The 3.8 is not a top end engine at ALL

My car is great (compared to stock at least) on the top end with the loudmouth and is even better now that I have headers and a hi flow cat.

[Timmy]

i went from 14.9 @ 93 to 14.3 @ 95 when i switched from open 3.23s to LSD 3.73s. you just have to keep practicing.

['98 BlackBird]

since I have switched from 3.08 to 3.42 I have seen a drop of 0.63 mph and a gain of .103 in the 1/4 mile and a gain of .074 sec in the 60'.
I did not see a difference in my times at all when I first put my new gears in, but after about 15-20 passes I started seeing a difference in my times and speed.

[MustangEater8251]

Keep practcing... I went 16.0 to 15.9s when I switched to from 3.23s and an open diff to 3.42s lsd, and plateaued at 15.8. Then a few more trips and I worked that down to consistant 15.6s

[WickEdSix9838]

i ran about .3-.5 quicker going from open/3.23 to 3.73/LSD, keep practicing....

[1DangerousV6]

wow...i'll be going from a 3.08 to 3.42 LSD over the winter and im REALLY hoping to see at least a .3 difference..

[GreenMachine]

For those who asked about my mods here is my list...
Dynomax ST muffler, underdrive pulley, k&n fipk, catco cat, paceSetter headers, NGK plat. spark plugs, new spark wires, BMR stb, 180 Thermostat,JetChip stage 2, Baja Beast Cam, 3.73 and Zexel Torsen LSD.

My CAM is 204/214 crower Baja beast cam. Nothing to huge, but it did have a noticable change.

When I did do the 15.7 run, that was in feb. The air was much cooler outside. I will keep on practicing and practicing.

With 145k+ on the engine, I hate to keep on beaten on her like that... oh well.... when this engine goes, then I will be forced to get another engine, but it will be bigger and meaner. [img]graemlins/naughty.gif[/img]

[BLLDOGG]

they made your top end suck??? well duh :rolleyes:

[GreenMachine]

i did not think it would be this bad [img]graemlins/barf.gif[/img]

tell me this, how will by 1/4 mile time drop if I cant hit the speed that I was hitting before with my 3.23s?

[BLLDOGG]

you car doesnt have enough in it to utilize the 3.73s.