7 replies to this topic

[Zyx]

Hi to all.  

 

I have a standard 1275cc engine and would like to turn it as a more powerful engine to have fun in the street and sometimes use it in street and rally racing.   I wish to bore the engine to fit +60 pistons.  I already has a standard compression, ported with big valves and with magnesium bronze valve guides cylinder head,  an HIF44 carb and LCB exhaust manifold.

 

Can you suggest, what type of pistons do I have to do, what camshaft (eg SW8, 276 ecc), crank and how much compression related with the setup that you suggests.

 

Thanks in advance for your reply.

[Northernpower]

+60 thou will give you 1330. If you want 1340 you'll need 72.5 pistons. Have a look on Keith Calver's website, I have them set up at 10 to 1 compression.

[carbon]

You can get a much bigger power increase by changing the camshaft than from overboring. And still keep it useable for the road.

 

Worth deciding first if you want to keep using it on the road. A full rally/race unit won't be much fun in traffic.

[Cooperman]

My full rally spec 1310 'S' is really not nice to drive on the roads. It is noisy, very low geared, harsh and lumpy.

[AlexMozza]

I've got a 1330 with a mini speed stage 4 head. Swiftune sw5 cam.
It's running with twin HS4 carbs giving a healthy 92bhp :)

[Spider]

For a street car, I wouldn't recommend boring any more than you need to for a normal reconditioning process.

 

If you do change the Cam and want it to be a fun street car, don't go too wild with it.

[KernowCooper]

276 setup correctly is very usable for the road

[carbon]

As Kernow Cooper says, set up correctly...

 

As well as getting head, inlet, exhaust, and compression specification right this spec will also likely need a custom ignition advance curve to give its best.

 

But get it right and it will be a flyer, and does not need 1340 - a 1275 or 1293 will be just as good for the road.

Edited by carbon, 13 February 2017 - 05:48 PM.