McDuck's Cobb AccessPort review, before/after dynos inside... delivers as advertised!!! Options

[mcduck]

Well, I held off on this mod as long as I could. At first, I wanted to make sure the maps were tweaked and no one installing would have any ECU/engine/trans issues from a reflash like this. Now that we are seeing GT-Rs running well over 500rwhp and not breaking stuff, I felt much better about adding the Cobb.

The goods...
I purchased the Cobb AP from Forged Performance in Marietta, GA. This shop has a great reputation and has supported our regional event, ZDayZ, for several years. In addition to purchasing the Cobb AP from them, I made the drive down Saturday to have the install done at their facility to ensure we could capture some same day before / after dynos.

Thank you's...
Before going further, thank you to Sharif and the guys at Forged Performance for taking great care with my car during my visit and walking me through the Cobb AP reflash process. This was the first GT-R they have had at Forged Performance, but I know it won't be the last. Also, special thanks to underpressure (Will) for some quick technical assistance regarding proper removal of undercarriage covers. We chatted with him by phone and, as I understand it, my stock dyno numbers are nearly exactly what he has seen for GT-Rs on this kind of dyno.

About the dyno...
Forged has a Dyno Dynamics 4-wheel dyno. It's a slick setup and allows a lot of corrections and ways to view the data. It is also known to pull lower lower numbers than similar dyno-jets when not using correction factors as we were yesterday. Regardless, we were not looking for through the roof numbers here. The goal was a safe install and to measure the actual gains.

Conditions...
Great day, low humidity, temps in the mid-30s. Last before dyno and first after dyno were separated by a time of approximately 75mins, most of which was taken up by downloading stock settings and uploading the 1.08 flash.

The Car...
My GT-R is pretty much stock with over 9000 miles on it. The only other mod I have are K&N drop-in filters, but I doubt they add much if any HP. Regardless, the baseline dyno and after were done with these installed already, so the relative change shown is all due to the Cobb tune. We installed the 1.08 tune for 93-octane gas.

Pics and details to follow...

This post has been edited by mcduck: Nov 23 2008, 11:23 AM

[mcduck]

PICTURES...

Apparently when you drive 4hrs for dyno runs and bring the first GT-R to visit the shop, you get a free car wash! Here, I step back and let Sharif get frostbite fingers cleaning the car while Sandy looks on. Wanted to make sure the redhead looked her best for the dyno and some publicity shots...


There we go. All clean and ready for an upgrade!


After putting the car on a lift to remove some of the undercarriage panels (to expose strapdown anchor points), the redhead is wheeled up onto the dyno and allowed to warm up for some baseline runs...


After approximately 2hrs on the dyno (including warmup, baseline pulls, reflash, warm up again, and final pulls), the end results looked like this (more detailed commentary in following post)...

[eclou]

You may want to consider changing the exhaust to something less restrictive. It seems that heat is something the std GTR already generates too much of, and taking some backpressure out should help drop the EGT's to a safer level - especially now since you will be elevating them with more boost and timing. That might also allow more significant gains to be achieved as well. The torque gains in the midrange look very nice.

[mcduck]

So, lets talk about the gains...

first, for those looking at the absolute numbers, keep in mind this kind of dyno reads lower. Sharif says it is not uncommon for a Dyno Dynamics unit to read 8-10% lower than a dynojet under same conditions. He felt the 406rwhp number we hit for stock config was very comparable to the 425-435 numbers we have seen from other GT-R owners' base runs. Also, underpressure confirmed via phone he has seen 406rwhp from another stock GT-R on a different Dyno Dynamics dyno. So we felt pretty good about the base.

The after dynos only revealed a gain of 28rwhp at peak. This hardly stacks up with Cobb's claims of +60hp/+70tq. Even if you figure that is at the motor and take into account 10% for the kind of dyno and 15% drivetrain loss, this would only translate to around 40hp at the crank. What gives?!?!?!?

The answer is simple as you can see from the detailed graphs below. The gains are there, they just are not at peak HP. I have highlighted the **area under the curve** in yellow in both graphs below. Whenever you mod, this is what you really want to know. Peak power is far less meaningful than getting a nice, fat expansion of your powerband.

As you can see from the HP/air fuel graph, the peak HP gain is only 28hp, but the maximum gains (almost throughout midrange RPMs) appears to be right at 60rwhp... exactly as Cobb claims in their advertising for 1.08 / 93 octane / stock tune. More importantly, there is a 40-60hp gain across the power band from 4500 to 6000rpm or so...




Maybe more important than rwhp tho, is rwtq. This is the power you feel and what gets you accelerating. In this case, the biggest gain appears to right at peak torque (approx 435rwtq), but like rwhp there are substantial gains over a wide range, from 3500 to 6000 rpm. And again, as Cobb advertises, the max gain appears to be right at +70rwtq!




Other items of note...
- Air Fuel ratio starts at 13.0 and drops to 11.5 from most of the power range now. Very safe, efficient range for a turboed motor

- Boost was 9-11lbs stock and now runs 10-13.5lbs with Cobb tune

This post has been edited by mcduck: Nov 23 2008, 11:24 AM

[mcduck]

I **hope** this works, but may be limited by bandwidth I have available to host. If someone can grab these vids and post somewhere for share, you have my permission to do so.

STOCK DYNO RUN

COBB 1.08 TUNE for 93 OCTANE DYNO RUN

[mcduck]

Finally, with all the work done, it was time to take the redhead out for a spin. So, off the dyno, in the air to have undercarriage covers placed back on, then out into the night...

[mcduck]

Driving Impressions...

OH MY GOD!!!



Prior reports are not exaggerated. This tune really brings the 3.8TT to life. I think the most striking part is the power gains are almost completely in ranges you would use on a regular basis... when you downshift or just need a little extra zip when already rolling.

From a standing launch, the car feels stock.... for a fraction of a second! This is probably good since more power at the bottom end would probably cause traction loss and/or wheel hop, slowing initial acceleration and creating stress on drivetrain. After that initial fraction of a second, tho, the car just pins you to the seat. I mean the GT-R was quick before, but not it is scary fast! It really is like being launched from a cannon now... and mind you, that is without switching the VDC-off... just set everything to R, leave in Auto mode, foot off brake, and hammer the gas. WOW!

From a roll, downshift quick and the car catapults forward. definitely stronger from a roll. For those who remember Space Balls, it is like going from Ludicrous Speed to Plaid.

Nothing I can say here can do the acceleration justice. It's just there, whenever you need, like stock, but now it is amplified. Godzilla really roars with any touch of the right pedal. For the price of the Cobb AP, it is crazy not to buy it. This car continues to astound me. I could not be happier with my purchases (car and Cobb). My GT-R is now at 9500 miles and that number is likely to continue to climb... very quickly.

[zeyd]

do you plan to track it now ? just to know the differences


i like your posts. keep them comin

[mcduck]

do you plan to track it now ? just to know the differences


i like your posts. keep them comin

At some point, I will take it to HPDE again. The most like next may be VIR in February. If it's convenient, I may get to a 1/8th or 1/4 mile, but I didn't buy my car for drag racing. so I'd either be out with a car group or just really bored for that to happen.

[Neoseven]

You did it! Am I going to be one of the last holdout's for tracked cars not running the AP? Nice review.

[Justice]

Nice ride, McDuck!

[MindlessOath]

im uploading them to streetfire
since i wont be around do a search for "mcduck's"

[mcduck]

im uploading them to streetfire
since i wont be around do a search for "mcduck's"

Thanks! just need to drop the links here. My bandwidth is pretty good, but it is limited. Streetfire would be better. I should just start an account there.

[underpressure]

Should have come out today

http://www.nagtroc.org/forums/index.php?sh...c=26625&hl=

[Booooh]

Streetfire: Stock Run...

Streetfire: COBB Run...

Nice results and a great review of the day you had...

Cheers,
Ben

PS Used the links of Mindlessoath's uploaded versions...

This post has been edited by Booooh: Nov 23 2008, 05:01 PM

[rabenoja]

Great review McDuck! The car's looking good!

[gtrcowboy]

Excellent write up McDuck! You nailed the Cobb AP experience to the T.

Cowboy

[GT3240x2]

Great review. Good stuff!

[amfaster]

Your car is between 500 and 520 whp on a good dyno jet.

[trumperZ06]

McDuck, we now have at least three and possibly four GT-R's all showing the same rwhp. ie. 406 hp.

It's beginning to look like the "stock engines" are SAE rated at ~480 hp. at the flywheel.

This indicates more than the touted 10 percent drive train loss reported by Nissan.

Also, another GT-R was dyno'ed in Atlanta

with the Cobb Access Port mod:

438 rwhp.
451 ft/lbs. torque.

Looks like we are starting to get some real data on the GT-R's

that are being delivered to customers !!!



Hhmmm... seems as though it doesn't always agree with Nissan's PR !!!