So i'm planning 2 upgrade my savage 25 with a 4.6 engine,still don't know which one, the K OR F.... But anyway to do that what other parts should i upgrade, for that strong engine.................
The F4.6 is an Ofna engine, it is more reliable and runs much cooler than the K4.6. The K4.6 and the K5.9 are manufactured by Axial, one of the worst engine brands IMO. Very poor quality control. Their bearings are complete crap too.
If I were you I would buy a LRP .28 or .30, or a Picco .28. You will not outgrow those mills and they will last a long time. The F4.6 is not a bad choice though, they go cheap on E-Bay.
For upgrades a set of aluminum clutch shoes and 1 mm springs and a new tuned pipe are all you really need. Hit E-Bay and stock up on Dogbones and differential parts. Tuned pipe, I'd run this one with a one piece header designed for the Savage. http://cgi.ebay.com/LOSI-LOSB5059-H...0557868146?pt=Radio_Control_Parts_Accessories
The header pipe you need http://cgi.ebay.com/RD-Logics-Hpi-S...0171444209?pt=Radio_Control_Parts_Accessories
Or this package will work good too http://cgi.ebay.com/HOT-BODIES-6121...0356552798?pt=Radio_Control_Parts_Accessories
Reason I recommend these pipes is HPI's tuned pipe has too big of a stinger which causes performance issues and makes getting a proper tune impossible. It's 10mm's and most BB exhaust pipe's run an 8mm stinger. This causes a loss of backpressure. A good tuned pipe makes all the difference in the world.
Clutch shoes http://www.vp-pro-usa.com/rc-parts-...ypage_images.tpl&product_id=90&category_id=22
I have ran these for a while now, they are quite possible the best clutch shoe on the market. Grab good, last 3 gallons easy, run cool and need little to no maintenace.