track night round 2

[Juanmiguel]

First I want to say that I know that upgrading the exhaust past the cat in these cars is normally not seen as something that will bring much benefit, but in my case it did.

I changed everything from the header outlet to the mufflers with 3" crush bent tubing and a 3" glass pack. 2.5 inch tubes at the stock mufflers inlet.

The gains were noticeable right away and I tested it at the track tonight. I dropped at least 3 tenths of a second on my best run compared to the last time I took it there, all KR is gone and running 20.5* of timing, I will probably drop to a 3.0 pulley soon. All this just by doing the exhaust upgrade.

The problem now is that I've got even less traction now. On the 2 first runs I spun the tires from 0 to 50.

first run:
me vs 2005ish stock mustang GT convertible auto trans.
GTP ET: 14.56
mustang ET: 15.57

second run:
me vs 300C SRT8 unknown mods (not sure if any)
GTP ET: 14.53
SRT8 ET: 14.07

that same srt8 was running 13.60s later on, he also had issues hooking up even though it's RWD.

my best run was a 14.27 when I finally got it to hook a little better, but still has room for improvement, it can probably run 14.00s with good traction. My best previous ETs where in the 14.60's with some KR and less traction issues lol.

Keep in mind this is at 5000ft high and i'm too tired now to make the conversions for you guys lol.

Sorry no trap speeds or 60ft. times are available either =(

 

[AmericanSoldier]

though its sweet you got a new PB but without 60ft, or trap speeds theres no way to tell if your car is faster or if you just drove better (or weather was cooler,better track prep, better gas etc.)


and theres no way you got .3 knocked of your ET with a catback unless you are at 800hp and the 2.25 exhaust w/ubend etc was causing a HUGE restriction:th_thumb-up:

 

[siLversLeigh]

I have a hard time believing any 3 valve mustang ran a 15.5 on a full pass.

 

[blueguy]

Fer teh Stangbanger...15.50 @ 5000 ft Silver would translate to a 14.539~ish, not TOO bad for an Auto 'Vert that was probably stock IMO.

For the Serteight...not stock, no waiz. Probably either a small shot of giggle juice or some serious bolt on love. It took a cammed/full exhaust SRT8 Charger to run mid 12's on slicks here and people were hookin'...so yeah...

14.07 = 13.19
13.6 = 12.75

.9380 seems to be the ET conversion rate to sea level.

If that is the case, your still running mid 13's. You need to make it to Ohio next year somehow...

14.56 = 13.65
14.53 = 13.62
14.27 = 13.38

 

[Juanmiguel]

thanks for the conversion Nick. I also hightlighted the altitude notice since my threads in this section always seem to be headed in the same direction lol.

I'll definitelly be there next year. After I get injectors... these are at 18 IPWs now =(

 

[darkhorizon]

thanks for the conversion Nick. I also hightlighted the altitude notice since my threads in this section always seem to be headed in the same direction lol.

I'll definitelly be there next year. After I get injectors... these are at 18 IPWs now =(

these = stock injectors?

Also, at altitude... turbo cars use a MUCH different conversion formula than anything else... Supercharged cars can typically pulley way down as well... So using altitude as an excuse and usinga typical "my 88 iroc" conversion formula is very deciving.

A turbo car that has a properly sized or slightly too large turbo will only lose 1-4% of its peak power at 5000ft over ~1000ft. The M90 operates in a very similar way when pullied down to compensate... blowers and turbos both are not heavily effected by RPM changes as much as they are effected by pressure ratio changes...

 

[Juanmiguel]

these = stock injectors?

yes.

If what you say is correct, I could perhaps run this setup on a 2.8 pulley? I think I would definitelly run mid 13s on a 2.8.

I can definitely drop to 3.0 now, but I'm not so sure I could run a 2.8. I guess there's only one way to find out, right?

Perhaps I could also get a 2.8 and try out at the track once I get larger injectors. Although I don't think I would daily drive on the 2.8 at all lol. But it would be fun if I could use it for the track and run 13s. Probably would need some drag radials too.

 

[blueguy]

these = stock injectors?

Also, at altitude... turbo cars use a MUCH different conversion formula than anything else... Supercharged cars can typically pulley way down as well... So using altitude as an excuse and usinga typical "my 88 iroc" conversion formula is very deciving.

A turbo car that has a properly sized or slightly too large turbo will only lose 1-4% of its peak power at 5000ft over ~1000ft. The M90 operates in a very similar way when pullied down to compensate... blowers and turbos both are not heavily effected by RPM changes as much as they are effected by pressure ratio changes...

Good thing no one was talking about turbo's...also...the average conversion for "basic" meaning less than 400~whp supercharged cars is around .9750 vs. the .9380 which was based for N/A motors.

So actually, my conversions are pretty spot on, especially for his mods and lack of tracion and nearly static injectors.

 

[darkhorizon]

yes.

If what you say is correct, I could perhaps run this setup on a 2.8 pulley? I think I would definitelly run mid 13s on a 2.8.

I can definitely drop to 3.0 now, but I'm not so sure I could run a 2.8. I guess there's only one way to find out, right?

Perhaps I could also get a 2.8 and try out at the track once I get larger injectors. Although I don't think I would daily drive on the 2.8 at all lol. But it would be fun if I could use it for the track and run 13s. Probably would need some drag radials too.

I dont see why not... I have never had much issues maxing out stock injectors on a VS cam car at 700ft.... Most cars would have 42s running at 80-85%.

Injector duty is your best gauge on how much air you are moving, not boost pressure/pulley size.

So actually, my conversions are pretty spot on,

Not really, 13.6-13.8 is pretty common for a 3.4/downpipe car at sub 700ft. Like I said he could easily run within .2-.3 of what he would run at lower altitudes with a pulley swap on the blower. I was comparing turbos because they operate very similarly to a blower that would allow you to adjust pulley size to compensate. A turbo naturally will spin faster at higher altitudes, a blower can to you just have to "tell it" to.