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JCR // DYNO TEST (Part1) - JCR vs OEM vs XXXXXX Headers

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JCR // DYNO TEST (Part1) - JCR vs OEM vs XXXXXX Headers

Old 03-10-2019, 08:23 AM
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JCR-Porsche when is part 2 going to be shared with us?
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Old 03-14-2019, 11:59 PM
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Here is a video of my car, at the end of the video a launch control is done. I am running JCR silenced bypass center + dundon race headers
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Old 03-15-2019, 01:17 PM
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Originally Posted by GT3 KSA View Post

Here is a video of my car, at the end of the video a launch control is done. I am running JCR silenced bypass center + dundon race headers
So pimp... ;-)
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Old 03-15-2019, 08:56 PM
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Originally Posted by JCR-Porsche View Post
Hey all,

As some of you may have seen we have been at the dyno on and off for the past week testing future products and also conducting a huge amount of comparison tests.

We have so much data to share that I have decided to split the results in to two separate forum posts as to keep things a little more simple and keep each post on message.

In this first post (Part1) we will be exploring the differences in as much detail as possible between the brand new JCR Inconel Race Manifolds / OEM Manifolds / XXXXXX Manifolds in a series of tests as detailed below

We hope you enjoy the read and we welcome your comments and any questions!


~ ~ ~ ~ ~ ~ ~ ~

Dyno Testing Notes

Firstly the factory Porsche PIWIS III tool was used to lock the car into dyno (roll) mode as to prevent any electronic interference due to running the car in 2WD on the Dynapack hub dyno. This is to ensure that the results are not affected in any way. Linked dyno’s will still cause torque inconsistent interference from the ECU when the car is not in ‘Roll Mode’ and with us running the car on a Dynapack hub dyno this meant due to the the stationary front wheels it would be impossible to test without access to this factory tool.

All tests were conducted in 5th gear with AIT monitored with both the dyno's own temperature probe as well as the Porsche PIWIS III tool via OBD logging to ensure the car was not torque limiting due to any unforeseen reasons which again could have an effect on the consistency of the results.

We selected 5th gear as we feel this is the most representative gear for circuit driving, most circuits you peak around the top of 5th gear. Running in 4th gear yields better results of course (and we tested this also) but importantly all runs were completed in 5th for absolute consistency.

The car was ran on Shell V-Power 99RON throughout the day, one tank, no changes. This RON rating of 99 converts to US AKI or (R+M)/2 - 93. So nothing special here. More info below on the fuel used during the dyno test.


For each and every run the position and fan speeds were all consistent. We monitored AIT’s with the Porsche PIWIS III and with the Dyno’s own temp probe, the delta between the two was never more than 2 degrees C and importantly all runs were below the magic 68f / 20c with the ECU kept happy and in its optimum map.

We completed a total of 8 power runs on the dyno per configuration, allowing the car to cool adequately between runs (1min) as to not skew the results. We found that during the first 3 runs the results would settle, with the 4th / 5th / 6th run being very consistent to one another and depending on the set up the 7th & 8th run starting to show the effects of higher AIT (more on that later)

You’ll notice that throughout this test we have our Superlight Titanium Tips installed. This is consistent between all runs during the whole dyno test with the JCR Superlight Titanium Tips being installed. The reason for this is due the material and weight the JCR Titanium Superlight Tips cool so much faster than the OEM tips it allowed for far faster exhaust swaps during the course of the dyno test. In (Part2) of our dyno test results we completed a comparison between OEM and JCR tips to ascertain if there was any performance advantage but importantly for this particular test the tips were consistent across all configurations tested.

Now, onto the testing and results..

~ ~ ~ ~ ~ ~ ~ ~

Manifold Comparison Test Brief

In this section of the dyno test we will be testing our new JCR Inconel Race Manifolds vs OEM Manifolds vs highly regarded and proven alternative set up which we shall refer to as XXXXXX.

The baseline for this test is of course the factory set up (plus JCR Titanium Tips) which we will refer to as Config1, this will be our start point.

~ ~ ~ ~ ~ ~ ~ ~

CONFIG 1 - OEM Manifolds / OEM Side Silencers / OEM Centre Silencer / JCR Titanium Tips

Total Exhaust Weight (35.06kg / 77.30lbs)
Weight saving (-1.08kg / 2.38lbs) vs 100% OEM exhaust


The purpose of this test was to create a solid baseline for the OEM exhaust system to use as the benchmark for the subsequent exhaust configurations tested.


Ambient Air Temperature - 10c
Air Intake Temperature - 11c

Baseline dyno results



The baseline data is as you would expect and in line with figures logged from other 991.1 GT3 RS on similar dyno’s / weather conditions / fuel etc.

~ ~ ~ ~ ~ ~ ~ ~

CONFIG 2 - XXXXXX Manifolds & Valved Side Silencer Bypass / OEM Centre Silencer / JCR Titanium Tips

Total Exhaust Weight (19.36kg / 42.68lbs)
Weight saving (-15.70kg / 34.61lbs) vs Config 1


As above, this test will determine solid data for XXXXXX to be compared to Config 1 & 3.


Ambient Air Temperature - 10c
Air Intake Temperature - 11c

Config 2 dyno results

Peak HP & TQ vs Config 1

Peak Delta HP & TQ vs Config 1



Unsurprisingly a solid gain in HP / TQ and delta from base (config 1) and gains are in line with highly documented results when this exhaust configuration is installed on this platform (991.1 RS)

~ ~ ~ ~ ~ ~ ~ ~

CONFIG 3 - JCR Inconel Race Manifolds / JCR Titanium Valved Side Silencer Bypass / OEM Centre Silencer / JCR Titanium Tips

Total Exhaust Weight (14.93kg / 32.92lbs)
Weight saving (-20.13kg / 44.38lbs) vs Config 1
Weight saving (-4.43kg / 9.77lbs) vs Config 2


Swapping out XXXXXX manifolds & valved sides we then install the JCR Inconel Race Manifolds together with our own JCR Titanium Valved Side Silencer Bypass in combination with the factory centre silencer & JCR Titanium Tips in order to achieve a representative set of results based on running a comparable set up.

This test will allow us to compare directly the differences in performance & sound to Config 1 & 2.


Ambient Air Temperature - 10c
Air Intake Temperature - 11c

Config 3 dyno results

Peak HP & TQ vs Config 1

Peak Delta HP & TQ vs Config 1



Interesting results, the peak HP / TQ figures and the shape of the curve. Config 3 showed the highest peak HP & TQ numbers from the best combined with solid gains from 4250rpm to redline vs Config 2.

~ ~ ~ ~ ~ ~ ~ ~

Comparison Summary - XXXXXX (left) vs JCR (right)


An overall reduction in weight of 4.43kg / 9.77lbs comparing Config 3 and Config 2, not insignificant when the weight is all rear of the rear axle.

We can, and will drop 25-30% of our current Inconel Race Manifolds weight with our Superlight version through use of thinner gauge and a lighter weight flange design however we feel where we have settled with the production version gives us a good reduction in weight vs OEM combined with very solid long term reliability. This is what I anticipate the vast majority of customers will opt with.

Modularity & Fitment

One big positive for the JCR Inconel Race Manifolds in this comparison is their modular fitment capabilities. A true direct replacement for the OEM exhaust manifold enabling customers to enjoy a wider range of exhaust configurations from various manufacturers (if they so wish)

We also retain the single piece flange design in order to make fitment a breeze and importantly none of the primaries cover direct access to the head studs again ensuring a simple, quick and perfect fitment every time.


We noticed a distinct change in sound characteristics between Config 2 & Config 3. We were unable to be pick up with true accuracy any noticeable dB meter reading differences however to the ear and on the video the sound is quite noticeably different.

A more crisp & clean ‘exotic’ sound with Config 3 and a deeper more bassy old school tone with Config 2, I expect the specific material choice primary lengths and diameters are all at play. Just an interesting observation and compassion which very few will invest time and money to explore.


Starting from the beginning of the pull, between 3250rpm and 4250rpm the XXXXX develop more power and torque than the JCR Manifolds, however from 4250rpm to redline the JCR manifolds hold the advantage with peak delta in WTQ landing at around 5400rpm of 14.63WTQ and peak delta in WHP of 11.28WHP

Peak Delta HP & TQ - Config 2 (solid) vs Config 3 (dashed)

Comparing peak WTQ for the two set ups yields similar results with both production peak WTQ around 6400rpm but the JCR holding the advantage of almost 5.88WTQ at this point.

Peak WHP is again near redline with the numbers in Peak WHP mirroring peak WHP delta as above of 11.28 WHP.

Peak HP & TQ - Config 2 (solid) vs Config 3 (dashed)


As for a forming a definitive conclusion on this test, we can only present the data as we tested in the fairest possible circumstances. Of course with any test of this nature so many questions can be raised and due to the results we found and have presented I very much expect they will be. We will let you form your own opinion on the results but of course welcome any and all questions.

Its difficult to explain the reasoning for the differences highlighted during this test but some could be attributed to us at JCR developing our Inconel Race Manifolds specifically on the 4.0 rather than the 3.8 991.1 GT3 engine. Its very obvious even just visually the stark differences in the two designs with us opting for smaller diameter and shorter length primaries, doing away with the marginal step in the primary also (most probably going some way to explaining the small torque loss vs XXXXXX between 3250rpm & 4250rpm) in favour of a shorter overall primary length focussing on the performance from 5000rpm to redline where we feel these engines are best enjoyed!

Most importantly overall however is the fact that we feel choice is a wonderful thing and we’re happy to be able to provide a viable alternative which importantly combines the modular nature of all our exhaust systems (direct replacement for OEM Manifolds in this case) in a lightweight durable package which makes great gains in HP and TQ.
What is the weight difference between stock and aftermarket parts used?
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Old 03-16-2019, 12:18 PM
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Anyone running race headers with race pipes? Curious how loud it is.
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Old 03-16-2019, 07:32 PM
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Originally Posted by drdonger View Post
Anyone running race headers with race pipes? Curious how loud it is.
I'll answer this soon

Race pipes going on my car Wednesday, race headers going on in a month or two at most. I'm currently straight piped with fabspeed/soul and it's bassy and not as a screamy as it is throaty, but it is very loud. I have a feeling the full JCR setup will scream and be very high pitched.
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Old Yesterday, 05:04 AM
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Originally Posted by fxz View Post
Valved Silenced Race pipe Vs
Not Valved Silenced Race pipe
are the silencers the same but one with the valves?
or silencers are bigger/smaller ?

How do they compare to
JCR center with silencers ? bigger/smaller silencers here?

They look like motorcycle or r race cars silencers where they are changed frequently, for JCR silencers how many miles before the carbon build will require new silencers?

I would like a table with dB instead of numbers from 1 to 11,
is there any electronic dB measure in the cabin available or is it just the classification table based on opinions?
Worth to ask and to mention that with any exhaust modified system
over 100dB there s a serious risk to become deaf
over 120 dB is certain to become deaf
any chance?
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