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There was a mobile dyno in town last Saturday (4/20/13) at the Pepboys Car Show so I put my car on. The car's only performance changes are: Mac longtubes, Mac ProChamber, Bassani Race mufflers, and 4.10 gears.
The car was dynoed with just 4.10 gears and 87 octane last year (4/21/12) to get a baseline. Stock numbers were 270 RWHP and 292 RWTQ. Dyno below:
It was then dyno'ed with the above mentioned parts installed and 87 octane again. With exhaust, numbers were 283 RWHP and 296 RWTQ. Dyno below:
Below is a table of the changes in performance. I made a mistake in the most recent dyno in not having them start at the same RPM so the data is not as accurate as it could be below 3000rpms but, the basic story is yes, I lost some low end torque but were the runs to start at the same time, I would expect it to be single or low double digit losses (not 30% as pictured).
I picked up peak gains of 13rwhp and 4rwtq. Non-peak max gains were 14.51rwhp and 14.41rwtq. The average was 3.4% gain in power across the rpm band from 2,700 to 6,100 rpms.
Here are both runs plotted together:
I knew that most of us knew that a full exhaust isn't going to post major gains by itself but it is a building block for a stronger car. Before now, I never could find a dyno on just these parts (mostly because it just isn't very cost efficient to do a dyno after each round of mods) but here is the proof I was waiting for. So for all of you in the future, you should be able to better determine where to spend money and what to expect from it. Using a 91-93 octane tune would have likely netted me another 5rwhp and 5rwtq but I just remembered that I didn't even think to switch it (although not sure how great a canned 93 tune would have been).
The next round will be Steeda Charge Motion Delete Plates, Steeda Under Drive Pulleys, WMS High Velocity Intake, and an 87 and 93 octane tune.
Ricardo, the Mac longtubes I have are more mid-length but no one calls them that. There was an article done years ago on a blown 05 GT and the Macs came out with the best gains. They provide a solid platform for any future mods. I also had mine ceramic coated.
Updated the first post. Finally got the dyno runs from the shop for the baseline. Picked up an average of 3.4% based on the new more accurate dyno run (vs my old plotting of 3% gains from 2600-6100 rpms). Also significant is there wa no mid range loss which was previously plotted and resulted in a 1rwhp/tq loss for about 300 rpms in the mid range.
All runs were on 87 octane. The next round of mods will be done on 93 octane. Because I don't want to drop $150+ on more dyno runs, I am going to do the intake/pulleys/CMDP's all at one time then actually get it tuned.
I was told by my tuners that a 4.10 will suck-up some of your RWHP? A stock GT 4.6 is around 270 RWHP, so with the mods you should have been higher without the 4.10.
What was the stock rear on a 05 GT?
A Reduction Pulley may damage other components by not providing enough cooling.
My difference with 87 and 92 is 10 hp but that's in the new Coyote.
The rear is the 8.8". I've also been told that 4.10's lower dyno numbers but my base line was 270rwhp and by baseline I mean just the gears. I was concerned with the under drive pullies but there has never been a reported accessory problem with the Steeda pulleys so I feel confident. My car doesn't get even close to running hot so I think I'll be fine but I will also keep track of it.
What CAI are you running? The FRPP has a wide pipe and a tub for the filter. No hot air in the intake, also has a moulding on top, which seals the tub with the hood. A lip over the radiator funnels cold air from the grill. Requires tuning.
I can't see top performance on a CAI with the filter having any access to the engine bay and hot air. On the previous question I asked what gear ration was your stock rear?
All GT's have been 8.8 except maybe an R. As far as ceramics I understand the coating traps heat and sends it out. No radiating into the engine bay and heating intake air.
IAT's are at or below ambient in all of my data logging. Gets cold air from the grille and is sealed and separated from the rest of the engine bay. I ran it for a month with a canned tune but it had idle issues on that so I removed it and am waiting to get the other parts in then have it tuned for all that stuff.
Stock gears were 3.55 but the entire time I have owned the car it's had 4.10's. yeah all S197 GT's are 8.8".
FWIW, I have a JLT Series II which is the short ram with a plastic partition that isn't completely sealed from the engine and when the car is moving the intake temp never goes above 10 degrees difference from outside ambient temp. So there's more cool air coming up in that driver side corner than you would think.
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