Hi guys,
I've recently completed a rebuild of a Smallport 4age. All is good with the engine except i've had to retard the base timing back to b/w 0 and 5 degrees to stop detonation.
Just to give you some background
Stock Bigport cams
Compression ratio is ~12-12.2:1
running on a stock bigport ecu with no error codes.
the cam timing is correct.
running BP ultimate with nulon octane booster to try and help.
currently setting up a water injection system to prevent knock.
Now i'm running the stock ecu only for the short term to run in the engine before running bigger cams and aftermarket ECU.
I feel the issue is too much compression with these cam in the bottom end as it can detonate when free revved from idle in neutral when running 10 degrees base.
I need some thoughts, would altering the cam timing to bleed off some compression in the low end to enable the timing to be increased back to stock and then use the water injection under higher loads.
thanks in advance to any help.
Thats what i've now realised.
whats a good DCR to be running on a 16V?
from using a online calculator its currently 10.9:1 would say 9.6:1 be reasonable
CR needs to match everything else. First step - get a decent cam, then get an aftermarket ECU.
The above opinion is just that - my opinion. It is not shared by any business that I am currently or have previously been involved with, nor any of their employee's.
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