Zafar Posted August 2, 2007 Share Posted August 2, 2007 What is the highest compression ratio you can run on a 1st gen 4e-fe/5e-fe engine without causing detonation or damage on normal pump gas?How can you check your normal unleaded gas octane level? Quote Link to post Share on other sites
Zafar Posted August 3, 2007 Author Share Posted August 3, 2007 Would 10.0:1 be too high? Quote Link to post Share on other sites
riko666 Posted August 3, 2007 Share Posted August 3, 2007 i ran about 10:1 on my 5efhe with no issue, just make sure you have some fuelling modifications to match "incase" Quote Link to post Share on other sites
Zafar Posted August 7, 2007 Author Share Posted August 7, 2007 I am planning on making a hybrid engine from a 5e-fe dis bottom end and a 4e-fe head(1st gen 5e-fe very rare). I have found the difference in compression between the engines is the amount of crown on the pistons. roughly 2mm crown=9.8:1, 1.5mm=9.6:1 and 1mm=9.4:1 I want to use the normal head gasket(TRD difficult to import). I will be using the 4e-fe pistons as the crown is 3.5mm which i can then shave to get the desired compression. If running the 4e-fe ecu which is mapped for 9.6:1 can i run this compression without any fuelling mods? Quote Link to post Share on other sites
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