4.5 engine mods / rebuild.
4.5 engine mods / rebuild.
Author
Discussion

a1rak

Original Poster:

556 posts

212 months

Tuesday 31st August 2010
quotequote all
just about to take out my engine for a thorough overhaull due to bad oil leaks and a lot of breather blowby. Whilst its out apart from the usual reconditioning process what else extra is worth doing. I would like to optimise the engines performance so any suggestions on improved parts or machining would be really appreciated. Dont want to spend a fortune on this so no really expensive ideas.


high52kojak

505 posts

226 months

Wednesday 1st September 2010
quotequote all
Dynamically balance the bottom end, crank to flywheel, match weight pistons etc. It is well worth having done in my opinion for a better quality build and hopefully a longer life.
Also raising compression by skimming the heads although you will ideally need to have the wire inserts machined into the liners to prevent the head gaskets going too soon.
Three angle valve seats, maybe some head work, get rid of those aweful casting defects.
Balance the combustion chambers.
Port the exhaust manifolds, (this gave me 5hp more),the mismatch as standard is shocking. Or fit the better quality ACT ones.
Re-map is probably the biggest thing for more hp on a 4.5 and go with short induction if thats your thing.
A good quality exhaust system with linked decats.
You can also make the butterfly spindles thinner to chase a couple more hp.
On mine I had some Bosch motorsport injectors fitted also, this gave me a few more horses but my old injectors were all different part numbers so not sure how much difference it would of made if it had the correct standard ones in from the start.

a1rak

Original Poster:

556 posts

212 months

Wednesday 1st September 2010
quotequote all
Thanks for the info, just out of interest what power is you engie producing. Anyone else got some more suggestions.

itiejim

1,822 posts

234 months

Wednesday 1st September 2010
quotequote all
I think most of the good suggestions have been made! I would definitely reinforce the fact that a full engine balance is worthwhile; I had mine done by Vibration Free who commented on how poorly balanced it was out of the factory. Money well spent.

stuthemong

2,532 posts

246 months

Wednesday 1st September 2010
quotequote all
what did the balancing cost, Jim?

Stu

itiejim

1,822 posts

234 months

Wednesday 1st September 2010
quotequote all
stuthemong said:
what did the balancing cost, Jim?

Stu
£405 which included crank, rods, pistons, clutch, flywheel and front pulley.

Edited by itiejim on Wednesday 1st September 23:24