Carb to supercharger pipe
Turbo Mini Forums

Hi

In parallel with the Turbo engine I'm finishing working on a SC car. Nothing to fancy, aiming for around 90-100bhp. I bought a second hand SC kit, janspeed or something simular, now fitted to rebuild 1275 with 266 cam and head reworked to get the CR to 8,8:1.

I'm about to fit everything in the engine bay I do however have some concerns about the piping.

no.1 diameter - carb has a 44 throat, pipe inside diamater is 38mm:


I should swap it for something bigger shouldn't I?

no2. connection on the supercharger isn't perfect as well as you can see underneath. I'm thinking about cuting of the pipe (or using large dia. one), making it more flat then round at one end and modifying flange to make it all fit better.




Sorry for poor pictures quality, too much light :)

no.3 I'm considering not using 1 solid pipe and instead going for a silicone 90 degree bend to join 2 more or less straight pieces. That should give me more possibilities to pack it all up under the hood the way I want it. I'm a bit afraid how will the silicone pieces cope with the fuel passing through it constantly.

In theory it all should work fine, but maybe I missing something important here.

Edited by SadamPl on 4th Nov, 2014.

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

Might aswell make a bigger better pipe whilst your at it...

If you want use silicone, because you're running 'suck through' you will need Fluoro Silicone, to withstand the fuel. I looked at this as I needed a 90 bend very close to the injector, but I couldn't find any large enough as they tend to be made for fuel / oil / liquids

It may seem odd that the link pipe is a smaller diameter than the carb, but I'd be tempted to leave it as it is. These long pipes between carb and SC are a bit crap. You need to keep the air speed up in them as they are prone to fuel pooling and poor idle. This may be a restriction at higher rpm, but otherwise your idle will have to be really high.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

I asked stuart gurr about this at vmaxscart, he said the link pipe diameter is correct

Be interesting to see of it made any difference. I doubt it would. Wouldnt bother changing the SC flange end, I don't see any real gain there. If you keep the small pipe just make sure there's a smooth transition between carb and pipe bores and maybe fettle the SC itself to remove the lump that overhangs the pipe if poss.

Edited by slater on 5th Nov, 2014.

You might want to consider heating the pipe, I have read to many stories about carb freezing.
Not sure if this is set-up related though.

Dazed and Confused....

You mentioned all of the things I was thinking about.

If I decide to fit a 2 pieces piping setup I'll be looking for oil/fuel resistant silicone bend. this should reduce the force on the bolts connecting piping to SC. I already have a suitable bracket to hold the carb in places.

To big diameter might be an issue indeed, that's why I asked your opinion but definetly i'm going to work on the flanges to make the transision more smooth. Even if it won't help too much it won't make thing worse and I prefer things to be lined up the best they can.

Maybe I'll fabricate a second set of flanges and I'll test to check it later.

Any other things I should watch out for?

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

I finally decide to do some work on the carb-sc piping, still in progress, but here is what I've got:




Carb flange reworked at enterence to make a smoother transition. SC flange enlarged to fit pipe flattened at one end. I welded it sticking out a bit in to SC so it position it self nicely there. Still need to clean up the welds and prep the mating surface.

While I was at it I started wondering where to put the pick ups for servo, megajolt and boost gauge. Any sugestions? Boost gauge somwhere on the inlet but what about the rest?

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

personally I'd want the carb as close to the supercharger as possible and with a pipe with a slightly rough surface for a few reasons. Long pipe equals loss of velocity and as someone else said there's a risk off fuel puddling due to that plus a smooth pipe. Your other option is replacing the carb with a throttle body and MS system

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I am limited by a few factors here. Space under the bonnet is one of them, there is no way I could squeez the carb closer to SC and at least with this setup it should get some cold air from the grill.

I know that suck through design isn't the best way to go but I'm trying to make it work the best it can.

So any advice on where to plug in vacuum/boost for the servo/MJ/gauge?

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

So the car is running. Pretty nice actually so I'm happy with that. But there are some additional issues. One of them is connected yet again with carb - SC link pipe.

When left idling there is quite a lot of fuel dragged from the carb but it doesn't reach the engine. it stays in the pipe runing upwards. When you rev it a bit the engine is flooded for a few seconds.

Are there any ways to cure this problem? It's not very bad but it may be annoying in the traffic + plus it does leak thru the air filter time to time.

I was thinking it may be connected to the electric fuel pump, but I'm running regulator, all set up properly and checked that again few second ago. With ignition turned on there is no fuel beign pushed through the jet.

Second thing is connected with seting up the mixture. I managed to trim the needle to run good AFR allway round (great guide on the forum BTW), will still monitor it and make some small adjustments, for now I'm only concernd by the fact that when going on constant speed - let's say 2k rpm on 4 gear when I start to accelerate the AFR shoots to 16-18 region. Just for a second or two and then it is ok (still accelerating). Should I be worried about that or is it normal? there was a bit of hesitation earlier and the AFR were even higher for a sec, but I managed to trim the needle to get it reacting and running properly.

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

The only solution I can see is running a smaller diameter pipe to try and keep velocity up and stop the fuel dropping out. Unfortunately this is the downside of these setups. You either need the carb closer to the blower or injection they are very flawed

wrap the pipe in copper pipe and run coolant through it so its nice and toasty and the fuel evaporates

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

That's a good call too actually. Heat the pipe like you would a manifold.

Have a look at grahamxx thread on tmf he made his own kit and used a double walled inlet so he could run a heater manifold the same as mentioned above

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Thanks for the tips. I'll have a look at the car again tomorrow and I'll try to come up with a setup that will be compact enough to squeez it in with a servo.

What about the second issue? It seams like the air is delivered straight away and fuel with a slight delay, hence the AFR reading off for a sec, but cars run fine, no hesitation or det. signs. Is that the way they work or should I be woried?

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

I went for a drive again to check how soon the pipe will absorb the heat from the engine got it to temp. and then cruised around for a few minutes, engine in normal working temp. and pipe still ice cold. It is less than 10 degrees outside today, so I guess it'll be a bit better in the summer but still I need to address that.

Since I'm very tight on space I figured an electric heater might work better and be easier to fit. Also I had an idea to use the same system that operates automatic choke on ol american cars. there is a pipe attached to the exhaust manifold that transfers heat to choke thermostat.

I'll keep you posted about the outcomes.

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

I have a VMAXSCART kit on my mini and it has taken quite a while to get it running well.
The best fix I did was to wrap copper tube around the inlet pipe and run the coolant through it. It does help in stop start traffic but not 100% resolved.
I think fuel injection would be the final fix?

Great pics, thanks.

What diameter copper pipes are you running?

Made in Poland build thread:
http://www.turbominis.co.uk/forums/index.p...tid=570363&fr=0

We had a supercharged Mini in at work a few years back that had the long style that suffered from icing.

We ended up making a new inlet manifold that was only about 8" long and positioned the carb just above the clutch breather. It made the engine a lot more responsive and also solved the icing but wouldn't work on a servo'd car.