I recently installed a 2.6" pulley and have gone back to the OEM cats, now I want to go play. I plan on going to the following and hope some of you are able to join me.


7/10 PTuning Dyno $75 (maybe a group dyno day in the future) CANCELLED, A/F sensor issue
7/11 Cecil Dragway, Test & Tune, $15, Depart 3:30pm, Arrive 5:30pm, Head home 10pm

1. 13.5 @ 103.7
2. 14.1 @ 103.7 (spun at launch)
3. 13.6 @ 102.8
4. 13.6 @ 102.4
5. 13.7 @ 102.3
6. 13.3 @ 105.0 (let car sit for 65 minutes and 84F)
7. 13.4 @ 103.7

7/13 75 80 Dragway Test & Tune, $30, Depart 3:30pm, Arrive 4:30pm, Head home 9:00pm

1. 13.6 @ 102.1
2. 13.4 @ 102.4
3. 13.5 @ 102.9

7/20 MIR, Test & Tune, $20 CANCELLED, rain

EDITS:
I received news from PTuning that their Air/Fuel (A/F) sensor cable was just damaged so I'm waiting until it is replaced before heading to their facility. 7/20/2012 received email, their A/F sensor is working again.

I asked about hosting a Jaguar and friends dyno day and have negotiated the following:
At PTuning, if we bring a group of 6+ cars on a weekday (M-F) the charge will be $60 per car and you get 3 pulls with an A/F tailpipe sniffer sensor. I will begin a new thread later about the dyno day(s).

 

1320, wish I could join u. Any reason for returning to stock cats? Is the 2.6 pulley the Eurotoys 3 lb pulley?

 

bfsgross,

The primary reason I went back to using the OEM cats was both Magnaflows failed. The catalyst broke away from the inner edges of the pipes and my car barely ran.

The second reason was that the exhaust system's sound was awesome for the track but too loud for normal street driving. It was very very loud! There must have been 15+ guys in all makes of cars comment that they really liked the way it sounded. Guys driving Vettes, Mercedese, BMWs, Camaros, Mustangs and even one guy who was driving a Viper on 495 (MD Beltway). MY WIFE HATED TO RIDE IN MY CAR and SHE REFUSED TO DRIVE IT.

Before performance began to suffer drastically, I began having random misfire codes. Soon afterward, over a period of 30-45 days, the engine tone changed a bit and it seemed to loose a lot of power. The cats did not melt down, I have no engine fuel delivery issues. The cats must have been rejects and now I am trying to have them replaced under warranty or money refunded.

Yes, the pulley is a +3 lb. steel unit from Eurotoys and even when the engine is hot, low end TRQ seems to have been a nice gain.

 

Understand the big noise due to hi-flow cats. I've been swapping in/out various muffler combos to deal with this. How do you like that 3 lb pulley's low end torque... when she's not hot? Feels like 500 lb/ft?

 

Since I installed the 2.6" pulley, our Maryland daytime temperatures have been above normal (as high as 108F), so I don't really know how she will run in the 70s/80s/90s yet.

Today, and the rest of the week, temps will be in the mid to upper 80s and my guess is the 2.6" pulley added 25+ foot-pounds to my car keeping in mind I no longer have the Magnaflow high flow cats installed. If I'm correct that may give me ~350ish foot-pounds of torque at the wheels.

I will post dyno results once PTuning has their A/F cable issue resolved:
Dyno Results: Stock*
Stock* except for exhaust due to a pizza guy hitting me before I could dyno stock. I installed Mina rear boxes and they did not have a measurable impact on 1/4 my mile times (estimate -/+5 hp/trq)
337 hp and 318trq

Dyno Results - Mod 1
No thermostat, no resonator, K&N drop-in air filter, Magnaflow hf cats and x-pipe
343 hp 327 trq

Dyno Results - Mod 2
Back to OEM cats and installed 2.6" pulley
3?? hp and 3?? trq

 

Great thread, thanks for keeping it scientific and also going to the track. 12.9's with very minor mods and a solid 107mph is awesome, congrats.

 

Here is an interesting article...
Eurotoys Pulley, PSE Port, Magnaflow Exhaust +71AWHP

 

Leaving now. Drop by if you can...

7/11 Cecil Dragway, Test & Tune, $15
Depart 3:30pm, Arrive 5:30pm, Head home 10pm

 

That's Avos responding to the OP who claims 75 rwhp with port/polish, 3 lb and magnaflow exhaust.

 

Here's an update from hanging out at Cecil County Dragway last night. My best and worst runs are attached.

They had several good running "real" street cars.
One Turbo Corvette (Black C5) in the 9s at 140+mph
A pair of Nissan GTRs (Silver, someone said STAGE 3) running in the 10s at 130+mph

It was a sunny and and nice and warm afternoon and the track's weather was:
Arrival 91F 68%RelHumidity
Depart 84 54%RelHumidity

1. 13.5 @ 103.7
2. 14.1 @ 103.7 (spun at launch)
3. 13.6 @ 102.8
4. 13.6 @ 102.4
5. 13.7 @ 102.3
6. 13.3 @ 105.0 (let car sit for 65 minutes and 84F)
7. 13.4 @ 103.7

 

This is why I don't race in summer! Not bad....

DA was 2200 at 5pm and 1800 at 9pm.

 

We need the "Chiller Killer" and/or methyl alcohol. Can't wait till a cool autumn run when ya pull off a 12.6 sec. 1320 ft. I do believe this'll happen.

 

@1320 racer, I think qwiketz has an intake tube or two left. I noticed a HUGE difference (didnt notice much with the cats), get on that if you dont already have one.

 

Am trying to see how one can get corrected HP figures from the MPH values.

What I am missing for your car would be the actual weight. Have you ever measured it? I have now used a curb weight of 4050, but assume your tank wasn’t fully full, I deducted 50, and add 150 for the driver, so 4150.

So first did the DA calculation, which was 2376 (using 30.1 baro, 88 F and 58 Hum)
DA Calculator - Density Altitude Calculator - DragTimes.com

Then I used your 105 mph figure, and calculated (on the same page) the corrected speed, which would be 106.

Using those figures you get an estimated HP value of 396 using the LRT formulas on this site:
Stealth 316 - Formulas for 1/4 mile ET & mph vs. hp & wgt

Al just for fun, will be more useful for yourself if you want to compare your own runs to see if you have made any improvements in tuning though.

 

I've put mine on the scale with slightly under a half tank of gas with me (~160lbs.) in it and I weighed in at 4210. I was in full street trim with the spare tire. My best run was a 13.9 @ 102 but that's at 6000' in altitude (worse when you factor in humidity and air density).

 

rasputin:
Thanks for the intake tube availability information.

avos and quartzstypeR:
I weigh 225 lbs and the fuel level is at (or under) 1/4 tank when I race. I have weighed my STR but I can't recall the exact number -- 4190 seems to ring a bell but I'm not sure?

all:
From my track and dyno experiences over the last several years, I say with certainty, that my STR benefits the most from cold incoming air, cold intercooler coolant and cool engine coolant more than the mods I've made:

• exhaust system (more hillbilly-type horsepower than anything in my case)
• pulley change (waiting for dyno results but I believe only low rpm torque and horsepower were increased and not peak -- so far my 1/4 mile track times show no improvement when ~80+F).

 

Yes, the mods do wonders with the motor cold. This is the basis for a "Chiller Killer" and/or methy alcohol injection...bringing and keeping "it" all together.