Wednesday, 8 October 2014

Chrysler Hellcat: grey iron block

Chrysler's V8 gasoline engine that powers the 2-door Dodge Challeger SRT and the 4-door Charger carries a grey iron cylinder block.

The vee block engine is based on the 6.4-litre naturally aspirated Hemi engine but the stroke has been shortened from 3.72in (94.6mm) to 3.57in (90.9mm). This gives a swept volume of 6.141 litres.

"Of course, we can redesign the engine to run under aluminium alloy but we would have to spread the bore centres and we would have to change a lot of things," Chris Cowland, Chrysler's advanced powertrain director told this week.

However, asked by Auto Industry Newsletter this week if the block was made from compacted graphite iron (CGI), Cowland confirmed the block is "gray iron which was the best option on durability and cost".

The engine, with an aluminium head, develops 707bhp (527kW) and 650lbft (881Nm) of torque. It has a peak firing pressure of 110bar. This power rating is equivalent to 115bhp/litre.

Cowland said that most gasoline engines today are designed in aluminium.

"If we switched from iron to aluminium, we could not get the bulkhead stiffness we need under those firing loads," he said.

Thus the Hellcat engine, which is machined and built in Saltillo, Mexico, requires cast iron. The steel alloy crankshaft has been modified to cope with the additional loads and coolant flow has been increased around the top of the bores to maintain their dimensions. The engine has variable valve timing.


Unknown said...

If they had decided to run for a CGI block it coluld have been interesting for a race trims like the major blocks in the Nascar Racing which are all cast in CGI since decades. They missed this opportunity for "cost reasons" by their stint solution. A CGI-block in´t costly nowadays

Unknown said...

I think it would be more consistent if the named the new engine " Grey Cat"
according the common block material.