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Head shim vs LC pistons (Real life comparison)

kinger said:
Not saying anything for sure but I know that people knife edge and balance a engine for the reason of reducing friction in the oil bath. If your rotating assembly is lighter then stock (is it?) it will rev easier.

More rev = more power is not 100% true but its close. You have 600 rpm difference which is the difference of 3 grams in a clutch which in your case is less then 3% change.

Bottom line I dont think there is a ton of difference.
Click to expand...
True, lighter assemblies will accelerate / respond quicker but that has no affect on HP output at a steady RPM...
 

And it was alot more than 3 grams. And it still only revs 10500 not 10700. I will weight the weights in it tonight. the old ones were 106 G . I belive these the head shim motor is around 94G
 
ok I dont dissagree with you on that point. but when you turn up the boost every psi makes a difference . Im not sure its 100 or 200 rpm but lets say its 200 rpm per psi. its still 30 hp.
 
Someone can correct me if I am wrong but I believe squash is the area in the cylinder that is squashed to the combustion chamber of head/ piston. You should gain power from less weight/rotating mass and balancing. Out of balance and rotating mass take power. I would hope you would get something for the extra cash spent! The low comp piston's will probably have a dish in them making for a beter squash=beter concentration in the combustion chamber and power gain.

The piston, rod and balanced motor SHOULD make more power! I think you said you had a slight higher compression ratio with the head gasket motor and that would explain the better low RPM response.
 
Doesn't MC express use a 60 thou head shim? With the split gasket that would take your compression ratio down to 9.4:1. That would explain some of the power difference.
Thanks
 
I had to take out 7 G of weight to acheve 10500RPM and the built motor would push all that weight to 10700RPM ! This is quite a HP difference. I can feel it also, there is a difference in power now.
Kinger its making much more power, it amounts to over 8% with your therory Thats about 20-25HP
 
It's everything to do with flame propogation due to the change in turbulence in the combustion chamber... Nothing to do with the lighter con rods, because rotating weight doesn't make HP. Maybe if it was carbureted and the lighter con rods changed the balance and effected vibrations and fuel frothing in the bowls changed the fuel delivery, but NOT on an EFI machine.
 
I'm torn between leaving this motor in or building back up my motor that has all the internal goodies . I want to leave this motor because I went to all the trouble putting it in. So if its true and a head shim motor builds the same ammount of power as a lc motor then where did the 7 grams of clutch weight go? From all the info I researched 7 grams of tip and mid weight is quite allot of missing HP. Perhaps its because the head shim has higher compression? Maybe its because it's running so rich( only the motor was swapped and it runs rich compared to my built up motor. Lol I'm just addicted to power ...
 
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