Thread: advice on build

I agree with Manny here.

i feel the increasment in compression increaes the motors natual ability to have great mass flow, without the turbo....the turbo wont have great mass flow becuase of this, but i do feel the compression plays a key roal in making up the ''lag'' on a larger turbo setup

You may feel it, but thermodynamics disagree.

ok what im saying is you have 2 motors one with 8:5:1 compression ratio

the other with 10:1 compression ratio

both with the same boost level both with same turbos

you are telling me that there will be no difference in the way the turbo behaves on either motor and both motors will have the exact same power curves.

theres no way. the compression ratio is in direct correlation to the way the turbo is going to behave on the motor.

the compression ratio isnt going to make the turbo flow more cfm. but the compression ratio is going to change the way the turbo acts

Wrong.

Many people do not understand the concept of "spool." Spool is the rate of change aka slope of the power curve. Spool is not when the turbo starts to create positive pressure.

In Lehman's terms, with all the things being the same (except compression ratio), the higher compression motor will make the power early but will still have the same slope as the motor with the lower compression ratio.

Here is my 3 min. Paint attempt to explain graphically.
This is what people think when they relate compression vs. spool. Notice the slope is different. The higher curve represents the higher compression ratio.


This is what is really happening. Notice the slope is the same, just that the higher compression motor is making power earlier but at the same rate as the lower compression motor. The turbo is not acting any differently.


*Forgot to label my axis. But we all know what a dyno sheet looks like

VE head info?

Coatings on pistons?

Why are they sold in 86mm, 86.5, and 87mm? bore is 86.5 right?

stock is 86mm

86.5 is to make sure the bore is straight on a used block

87mm is for slight displacement increase (recomended for sleeves at this bore)

87mm is safe for boost.

I ran 87mm bore on stock sleeves on my 500+ VET

yea solid deck blocks are pretty stable, i just see hks recomends the sleeves for that bore... but obviously they wanna market their sleeves lol

A VE head will fit on a DE block with minior mods.

Coating the pistions will give less friction on the cylinder walls. It is not a bad idea to do it will only help.

Stock is 86mm as said earlier and don't worry about sleeving your block with the amount of power you want to have stock sleeves will hold, just look at what Manny did with his.

Matt