Cam for a 4.5.

SeriesV8 · Post by **SeriesV8** » Tue Sep 10, 2013 6:48 pm

I've got a a 4.5 Rover V8. It has a 3.9 block bored out and with an Iceberg crank. The pistons are HC omega's with valve cut outs, the heads are heavily ported with oversize valves. It currently has a solid crane cam which i think has similar profile to the real steel rs256 profile. And running on quad 48mm dellorto's but I'm going to convert it to fuel injection with quad jenvey 48mm throttle bodies. I'm looking to lower the rpm range to give better low end torque and a range of about 1000rpm - 5000rpm as its to be fitted to a land rover. Piper cams have recommended their v8bp255 or v8bp270i cam for hydraulic lifters, and kent cams have recommended their m238 cam for solid lifters. They seem quite contrasting cams, does anyone have any thoughts?

Thanks!

DaveEFI · Post by **DaveEFI** » Tue Sep 10, 2013 10:32 pm

Don't think you'll get any benefit from throttle bodies at low to normal revs. Quite likely the reverse.

SeriesV8 · Post by **SeriesV8** » Tue Sep 10, 2013 10:44 pm

Thanks for the reply, why would the throttle bodies be disadvantageous over carbs?

Darkspeed · Post by **Darkspeed** » Wed Sep 11, 2013 9:36 pm

A JE 218 is a good compromise will take the edge off improve the torque and give a good wide torque spread.

kokkolanpoika · Post by **kokkolanpoika** » Thu Sep 12, 2013 5:38 am

What compression ratio you have? 10.5:1?

If the money is not a problem, i will go for throttle bodies. They will operate mutch better than any carb setup. And slightly smaller than 48mm for 4.5litre engine. Like 42-45mm

RS M238 cam with throttle bodies and correct compression ratio is quite civilized.
Like mgbloke say: The Idle with the mechanical 238 is surprisingly good.
http://www.v8forum.co.uk/forum/viewtopi ... &start=345

I do not see any reason to go for plenum. Throttle bodies will give mutch wider torque band. Idle quality is better etc..

SeriesV8 · Post by **SeriesV8** » Fri Sep 13, 2013 8:32 pm

The CR is 10.25:1 Thanks for the advice, after speaking to a couple of other companies, think I will go for the M238 and 45mm Jenvey TB's.

kokkolanpoika · Post by **kokkolanpoika** » Sat Sep 14, 2013 7:20 pm

10.25 is quite low with that cam. i have got M238 and i will run ~11.8:1. Dynamic CR is near 8.5-9.. don´t remember. Quench is also quite tight approx 0.8-0.9mm. So detonation risk is low.

Have you ever calculate your dynamic compression ratio?