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718 Cayman GT4 is here – at long last.!

MannyLon said:
Oh how I would love an exhaust shoot out. All manufacturers turn up at a neutral testing center and before and after claims can be settled:p
Click to expand...

JCR put out an open challenge to the market for exactly this.... guess what.... Crickets....

Like you and everyone else - in the case of all modifications and 'upgrades' - I just want to see what that best really is, with all the facts laid out - full transparency, no BS, because is it really can be a complete minefield, and then, everyone can make their own choices based upon their requirements and budget.

 
Did you guys watch the video attached to the link ?

Good points regarding the claimed power gains. Ideally ,I would want to see and hear a GT4 with the back box fitted. Have mine fitted and dyno tested before and after hopefully with a decent power gain (20 bhp would be awesome)

and improved sound with less drone .

I will keep dreaming and hopefully get the car out later today if the frost clears 😁👍

 
In case you missed it this is the before and after comparison for the Litchfield exhaust. As said, the blog shows a few experimental systems and although implied it’s not absolutely clear that the claimed 20hp gain is for the advertised system, although there’s no reason to believe that it’s not.

Jeff

Edit: See next post for correct graph

 
I think you've uploaded the wrong file there, Jeff...

EDIT: cross posted!

There are also pics of various exhaust configurations on the Litchfield page and the exhaust tips are not fitted to the car shown on the dyno. I'm not saying they're lying by the way, to anyone who thinks that's what I'm implying, I'm just saying the way they've presented their information potentially disputes the message they're portraying. A website tidyup would solve it though [:)]

 
Here’s Litchfield’s MAHA dyno running in 4WD configuration on their latest offering; a GR Yaris … impressive!

Jeff

 
I remember going round Cosworth when they were for sale and their dyno room had 3 engine dynos, with just one running it was quite noisy.

 
Coincidence that Jeff, I`ve been following their Yaris programme since driving one recently - definitely impressive [:)]

Was around dyno / rolling roads back in the day ... tuning Golfs and Escorts, even had a few passenger `laps`- surreal [:-]

 
Morning all [:D]

My car is returning to 9m next week to have the exhaust removed and the standard silencer put back on. We're working on v2 of the 9m silencer and mine is heading off to the fabricators for a couple of tweaks. It'll be interesting to switch back to standard again to compare the difference between them but going the other way this time.

As an aside, I'll be able to evaluate the LWFW as a mod in isolation which I haven't done before now. I'm curious to see how that alone affects the feel of the car so if anyone's interested I'll report back...

 
Dave,

Do you know what mods 9M are incorporating in the Mk2 version? Sound and/or efficiency?

As you say, it will be an opportunity to evaluate the LWF in isolation. Maybe you can persuade them to put the car on the dyno FOC to add to their literature. [;)]

Keep us posted.

Jeff

 
Hi Jeff,

The mods are going to be an attempt to reduce drone in the 2-3k rev range, and I've asked them to see if they can add a bit more silencing to the "valves closed" route if possible to give more of a difference between PSE on/off which at the moment is pretty minimal! It's all part of the development and feedback loop process and me trying to help them to produce a product with broad appeal. I suspect at the moment that fussy buyers would find the drone a little too intrusive. JCR seemed to have the same problem with their initial design - their current one is a v2 with added resonator tubes/j-pipes.

I did think about doing a dyno run on the car as almost standard, but I can't be bothered trekking it to the dyno place! If 9m ask for one I'll consider letting them take it, or I may pop along myself for the ride, but at the moment there are no plans to do so.

 
Understood Dave. Reducing droning is a worthwhile ambition, especially if it coincides with typical cruising revs, although a 2-3k rev range is quite wide - maybe 50Hz? - so a narrow-band device like a Helmholtz resonator could be of limited value, but I guess that any attenuation will be beneficial.

Mistakenly, I assumed that 9M had an in-house dyno so I can understand your reluctance to make a journey elsewhere.

Jeff

 
The dyno they use is an independent place and is around an hour away from their site, so it's a bit of a faff to get there.

It'll be interesting to see what they can do re. the drone. I've been doing a lot of reading around, especially on Rennlist, and it seems to be a very common result of changing exhaust components on the 4.0 engine Cayster cars. It's not a simple case of swapping stuff over these days unfortunately, the GPFs seem to create a "blowing over a bottle" drone effect that's hard to dial out unless you just reduce overall volume. This is the solution Porsche appears to have gone with which works for them as the EU legislative dB limits have also been reduced too, but it's a pain in the backside for the aftermarket guys trying to uncork the bottle...

 
All very interesting on the exhaust and sound difference along with the drone which is noticeable but I try to ignore it 🤔

I have noticed my car sounds different now its run in and over 5500M

Its certainly louder with the sport button on. I also saw this back box option on you tube which looks cool. https://youtu.be/q52Y1dnBJAI

 
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