Supercharge your Rancho

[andyowl]

We are just starting a new subject in the Bagheera section on "Supercharging your Matra-Simca". This is specifically about the Series 2 1442cc Bagheera but may also be of interest to owners of the Rancho.

Join us there.

Andy Owler

[andyowl]

Rancho specialists, may I ask your advice please?

I read that the Rancho had a lower compression ratio than the Bagheera with the same 1442cc engine. Someone told me that they achieved the lower compression by the use of a different piston height. Any advice would be very welcome.

I am tempted to fit the ex-Murena engine I already have but I need to do it quickly so as to have the blown car at NEC on November 13th.

Was there also a low comp 1600 engine perhaps on a Simca commercial vehicle?

They have said that the 1600 engine is not as strong as the smaller capacities particularly at high revs, but my Shorrock blower does not need to rev too hard and has a 6500rpm limit.


Andy Owler

[Matra_Hans]

Regarding Rancho engine: Accrding to the specifications only the Gran Raid version had the lower compression.

Regarding the 1.6 Solara engine: It was available in a 70 HP and a 90 HP version, but I do not have any spec. of the compression.

Hans

[suffolkpete]

According to my Haynes manual, all 1592 cc engines have a 9.35:1 compression ratio, but I suppose it's possible that cars produced for non-UK markets may be different.  With other vehicles I've worked on, the compression ratio is varied by altering the volume of the dish inthe piston crown.

[andyowl]

Thanks for the responses. I have made some progress today although I have not yet spoken to a man who might supply Rancho pistons!

I have the contact details of a man who can supply thick cylinder head gaskets. I'll call him tomorrow.

Several members have warned me that the 1600 engine is not very strong partially due to the non-symmetrical cylinder layout and crankshaft.

I am moving to the conclusion that I should stay with the 1442cc engine with Rancho pistons but with the stroke of 78mm reduced by crankshaft grinding to 77.2mm. This will give a reduced capacity of 1427cc and this when multiplied by the "forced induction factor" of x1.4 will give me a nominal capacity of 1995cc. This will satisfy the competition requirement to remain, after fitting the blower, within the original "Class" of 1401-2000cc. The reduced stroke will also reduce the compression ratio and any further reduction can be achieved by the use of a "decompression gasket".

The "decompression gasket" will cost about 120Euro and take 2 weeks to make. Specially made forged competition pistons are about 150Euro each (so Rancho pistons sound a good idea if they can be found!)

The design is coming together!

Keep the suggestions coming please.

Thanks

Andy Owler

[JV]

According to my Haynes manual, all 1592 cc engines have a 9.35:1 compression ratio, but I suppose it's possible that cars produced for non-UK markets may be different. 

Several English and Dutch sites with technical specs give the same info: all 1592 cc Solara engines had the same compression ratio of 9.35:1.