Micra Group A Rally Car

Low Rider

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I see 👍

Have people tried different design exhaust manifolds other than janspeed. ?
Matt Humphris has.

There are several manifold variants he offers. His Janspeed manifolds, which are essentially what Maniflow made back in the day, have much bigger ports which pushes peak torque and horsepower up the rev range. He also does a longer primary version to help boost torque. I believe he's done some dyno work on them and may have some info on benefits.

Eden from Gizfab does a few variants also but I don't know if anyone has had one on a serious motor on the dyno yet.

I'm also wondering what AP Race Engines may use as they seem to get good results out of CG13/CGA3 engines.
 
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Matt Humphris has.

There are several manifold variants he offers. His Janspeed manifolds, which are essentially what Maniflow made back in the day, have much bigger ports which pushes peak torque and horsepower up the rev range. He also does a longer primary version to help boost torque. I believe he's done some dyno work on them and may have some info on benefits.

Eden from Gizfab does a few variants also but I don't know if anyone has had one on a serious motor on the dyno yet.

I'm also wondering what AP Race Engines may use as they seem to get good results out of CG13/CGA3 engines.
Do you have any dimensions from the jenvey throttle bodies that people use on the micra ?

spacing between the bodies , what the size is the bore on the manifold side , is it the taper sf bodies most people use ???
 

Low Rider

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Do you have any dimensions from the jenvey throttle bodies that people use on the micra ?

spacing between the bodies , what the size is the bore on the manifold side , is it the taper sf bodies most people use ???
Yes, I have a set on my desk as it happens :)

Bore spacing is 79mm, bodies are SF taperbore 42-45mm. The manifolds are finished bored to 42.5mm from Jenvey but they end up 42.75mm to fully match the SF body units, at least they do on my set. Mine are however ex NME units with a different setup than they make now, as they have bespoke inlet trumpets with injector mounts for 4 stand-off injectors.
 
Yes, I have a set on my desk as it happens :)

Bore spacing is 79mm, bodies are SF taperbore 42-45mm. The manifolds are finished bored to 42.5mm from Jenvey but they end up 42.75mm to fully match the SF body units, at least they do on my set. Mine are however ex NME units with a different setup than they make now, as they have bespoke inlet trumpets with injector mounts for 4 stand-off injectors.
cheers do you have pictures please , how is the linkage on those ?

thanks
 

Low Rider

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this is the figures for the exhaust port , it made 152 bhp on the dyno ??? and i think there is a little more to come , as the janspeed manifold really isnt very nice
Well, if you really are flowing 114cfm @20" at 9.5mm valve lift, could you please put me in touch with whoever did your head work? :cool:
 
I did all head work myself , loads of time spent
I’m doing a new head with bigger valves at the moment between other things , will be going on the flow bench again
 

Low Rider

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I did all head work myself , loads of time spent
I’m doing a new head with bigger valves at the moment between other things , will be going on the flow bench again
Cool, home brew :)

The reason for asking was because I flowed a stock CG head at 10" and the exhaust peaked out at 45.3CFM at 0.400" valve lift (63.9CFM at 20").

So, flowing 114CFM shows a 78% increase if that's the case, which makes me wonder if I've misread the notes in the photo. Even at a full 28" those are impressive numbers for a stock set of valves. Given I'm running a turbo, exhaust gains make my life a lot easier :)
 
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