Roller12

Hi Bill Mitchell. I know it is 7800 rpm... but how could we explain that graph?

SBARacing

Thank you @DC021!!!
I just received my silenced valved JCR for my Spyder yesterday.
Installed it last night along with the Dummy GPF Delete OAP DIY as posted here by @DC021. The sound is perfect!!! Just the right levels of noise inside, and an unbelievable amazing sound outside (had the wife drive it down the road so that i can hear it unrecorded).
Couldn't be happier with the outcome.

For me it's: JCR silenced valved with the Dummy GPF Delete OAP DIY, at least for now.

DC021

Awesome! Glad it worked out for ya, out of curiosity are you getting the slight drone that other users of the JCR Silenced Valved rear section are experiencing? Wondering if the gutted GPF works as a resonator of sorts.

GT4_trip

I think it does. I was perhaps the first one on the forum to try this combo and was nervous. But I think with this set up I get less drone that with the stock set up and valves open all the time. At least to my ears

SBARacing

Took it for a long 1H drive today. I drone in any gear, RPM or seed. Highway and non highway, roof up or down. As said, perfect sound!
I would agree that the gutted may be helping here.

xstnte

dyno results from JCR exhaust manifold, JCR OPF delete + stock exhaust coming soon

JCviggen

I've seen a lot of dynojet graphs where the GT4/Spyder hits the limiter at 7800. It just seems slightly off on the RPM pickup/calc. as there are other types of dyno which do show the correct 8K max. So the GTS 4.0 stopping at 7600 appears correct if the dynojet is about 200 rpm off.

Roller12

Thank you JCviggen! What do you think of the différences between 3 and 4k?

Alpha Ice

I'm anxious to see how this performs, I'm hoping to go this route, just debating on if and when to pickup the OPF. Did you do the silenced or non silenced OPF? My end goal would be to run a valved JCR exhaust...but I'd prefer to have the silenced OPF and non silenced exhaust as I want a good bit of noise, but not having angry neighbors level of noise (maybe they are angry at me now and they don't say anything haha).

Bill Mitchell

I'm a bit confused(seems like I stay that way) about exactly what your JCR exhaust manifold is. Is this it? https://www.jcr-developments.com/por...el-rolled-tips)

JCR-Porsche

JCR INCONEL RACE MANIFOLDS

JC

khooni

goes to show how optimised the car is. even with the OPF, there wasn't much power loss. apparent that exhaust mods are mainly for sound. i wonder with full race setup how much hp can be gained.

Alpha Ice

It's only about 60ish hp and about 55ish torque with a proper race setup. There are quite some gains to be had, look at some of the JCR stuff.

khooni

really ? 60 Hp is a lot. I thought 15-20 is what you get for a full manifold to exhaust tip full race setup.

Alpha Ice

Most are getting 10, 15 or 20 from the manifold. JCR has a few pages here that show quite a bit more.
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