Race Engine Forum UK

Hi
Here is a picture of my supercharged Fiat x1/9 1300

Charlie.

Looks like a tidy installation. What'll she do mister?

Did you have to lower the comp. ratio at all?

thank you James

Hi,
The car will now happily redline in fourth gear , but I am using a knock sensing ignition retard unit with a 6500rpm rev limiter at the moment.
The compression ratio has been reduced to 8:1 by fitting a 1500 cylinder head. I am currently fitting an oil cooler and a freeflow exhaust and I need to change my final drive ratio to make the most of the torque now available. The car is currently running about 7 psi of boost and I don,t want to play about with that side until these mods have been made.

Charlie

Install the 1.5 MPI engine. Has the ratio: 8.8:1.

As a matter of interest which Fiat / Lancia models used the 1.5 MPI engine.
I know that a fuel injected version of the 1500 x1/9 was sold in the USA,
but I have not seen any 1.5 MPI engined cars here in Ireland.
8.8 : 1 compression ratio may be a bit high without intercooling for a roots type blower set up.
Charlie.

Some pictures as requested.

What's with freeze over on the carburettor?

Sorry Acki, what is your question about the carb. ? :?:

Charlie.

Charlie, Acki, hi

I think Acki means 'gauze' /perforated steel thing; and I will simply say - it's the air filter.
Unless he's spotted a intake refrigerant system.

GC

Charlie, hi

could you tell me what the long spindle does that runs along blower to carb please? Is it to run dual throttle plates?

GC

Guy - that is just the throttle linkage unless I've totally misunderstood what you are referring to. The cable running direct to the carburettor is actually the choke. The X1/9 throttle runs up the front of the engine with a linkage transferring the action to the #1 end. There is a bell transferring the motion from fore-aft to side-to-side. The "spindle" is the linkage operating the throttle...

Julian has it all sussed out correctly. Throttle motion is converted to push rod operation from the bell crank to the butterfly spindle. It allowed me to use the existing throttle cable set up. By using a side draught twin choke carb it leaves the option of bolting on a Jenvy throttle body if I want to convert to EFI at a later stage. Guy actually helped me with setting up the carb reguarding choke sizes, jets ect. Its currently using 25mm chokes, 165 main jets with 210 air correctors and no 10 emulsion tubes. 70 Idle jets & 75 pump jets. This set up is very drivable with just a tiny flat spot @ 2,500 rpm . It returns on average about 25 mpg. I had it set up with 28mm chokes initally ,this had great top end power and the induction noise was fantastic
but there was loads of hesitation on part throttle openings. I have plans to convert the side draught carb to progressive operation which may allow the use of the 28mm chokes without effecting drivability. If anyone has carried out such a modification, it would be great to hear from them.
Charlie

I mean Icing of the carb because the vloumex sucks soo much air.
You understand?

Like es gas bottle when you take much gas, the bottle gets on ice.

Aki, yes, same kind of thing, below 12 deg C atmos temperature coupled with the right condition of humidity, latent heat of vapourisation of the gasoline will chill the carb sufficiently to make water vapour from the air condense, and then freeze - on - and in the carb, blocking the air corrector jets.

Not good!

GC

Hi Acki, Guy,
Indeed the inlet manifold temperatures can be quite low and I have often seen the carb and plenum covered in condensation after a drive. Icing has not been a problem yet but it may occur in the colder winter days.