c20seh engine

[bigstevie]

im going to be stripping this down and doing bit work on this. looking to c if anyone has tuned/did upgrades on this engine. work im looking to do is:

1. bigger valves
2. high lift cam and pulley
3. 4 branch manifold and powerflex system

also trying to find any information as to where i can source these parts. cheers:thumb:

[MK999]

I'd leave the valve/cams sourcing to whoever you get to do the big valve conversion really, no doubt they will manage to get you cheaper prices than anywhere that will sell to you. Manifold wise you'll have to look at modifying a cavalier performance manifold if such a thing is easily available, otherwise custom!

[bigstevie]

cheers. just thought if am gna build an engine a may aswell do it right. got a 3 branch but its not in best of condition but will do for mean time

[MK999]

what kind of intake are you going for? not sure what the standard is like but you may not see the best possible improvement from a big valve head on standard intake, and it's not cheap to big valve a head as it means removing the valve seats, boring them out, replacing them and porting the head to match, a well ported head (without larger valves) may be the better option depending on your budget.

[bigstevie]

was just going to use the standard intake. the option of the well ported head sounds like the better option. just need to find someone that can do that work up here cheers

[Nova_Tek]

Why not go for a custom exhaust/manifold? Some porting and polishing with a set of good cams and a proper quality exhaust system should see some gain. Just depends what you budget is.

[bigstevie]

am doing it in stages just wen i have funds available. i mite yet sort a custom manifold-take my old one and c if they can make a copy.

[swedge]

i have a 20seh

its got a p&p head
272 cam regrind from auto sprint
4-2-1 and a 2" stainles exhaust

mines is running r1 carbs and megajolt so no inlet to worry about

ive always been told that the increase from fitting bigger valves against the price of getting the valve seats cut/removed isnt worth it unless you have money to burn

ive read project threads on other sites where people have fitted bigger valves and its made no difference to the power output

[mowgli]

going back into the 80's, CCC mag tried to budget tune up a 1.8 version of this engine, and did the head with surprisingly, no great gains..

the grA 1.8 rally astras were getting about 185hp but that was with hi comp pistons & modifying the injection.. so mega cost.