Micra Group A Rally Car

[Low Rider]

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.

 

[Steve green]

I spoke to Andy at ap about rods before , I think they had over 160 on the last one I believe

 

[Steve green]

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]

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.

 

[Steve green]

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]

 

[Steve green]

View attachment 60184

thanks , can that style of linkage be bought from jenvey ?

 

[Low Rider]

thanks , can that style of linkage be bought from jenvey ?

I don't think so. Jenvey certainly don't list that style online any longer.

Why, are you considering a set?

 

[Huggy444]

I don't think so. Jenvey certainly don't list that style online any longer.

Why, are you considering a set?

I haven't seen any leave the factory with a linkage like that, we moved to a new style a while ago!

Sent from my CLT-L09 using Micra Sports Club mobile app

 

[Huggy444]

I tell a lie, we do make those linkages still

Sent from my CLT-L09 using Micra Sports Club mobile app

 

[Low Rider]

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?

 

[Steve green]

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]

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

 

[Steve green]

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

I found my book and here is what the flow bench read when testing the inlet side. I found that these proof the theory , lifting the valve more than a third of the head diameter doesn’t gain very much , unless you go bigger valves

 

[Low Rider]

That's interesting. 172bhp theoretical potential on the intake. Making 152bhp means there's room for improvement somewhere. Wonder what the port velocities were like, (they suck on a stock head).

All valves tail off but you still need to lift them appropriately to optimise average flow.

The exhaust to intake flow ratio numbers are also interesting as a side note given all the tosh on these forums about them being too small

 

[Rally-mad-harry]

Hey guys
It’s been a good few years since I’ve been on here. But my Micra used to run the maniflow system with the longer group a headers and then the rest of the system was built in 1”3/8” I believe which had a Benefit over a normal 2” upgrade.

Had mine on the standard inlet for rally regs and made 123hp & 116lb/ft

I’ve just bought another standard cga3 for some development work. Looking to put into RWD potentially. Watch this space.

 

[fuzzy-hair-man]

Looking to put into RWD potentially. Watch this space.

A GA block bolts up to micra gearboxes so it makes sense the reverse is true, wouldn't seem to help much but there's a North south ga16 in Serena van thing, we didn't get it here (sr20 only here) so it's a dead end for my purposes but maybe they got sold over there. Thought a CG13DE in a datsun 1200 would be neat.