[David.kinter]

Other than compression ratio, how does deck clearance affect an engine?

With a 4.125" bore, 3.4" stroke, .041" compressed gasket size, 70CC combustion chambers and 0.000" deck clearance comes to 10.43:1 compression ratio.

In a boosted application with the above build is it beneficial to be "out of the hole" by a bit or "under the hole"?

Just in case the information is needed the parts I am putting on my list for the build is as follows:

Dart Iron Eagle 363 rotating assembly
-(Includes forged crank, forged H beam connecting rods, and forged flat top pistons)
TFS 225CC Highport heads
TFS Box-R-Series upper/lower intake
Custom grind cam - undecided on what manufacturer

Second set of questions:

Single turbo, parallel turbos of equal sizes, parallel turbos of staggered size(One smaller one larger), hybrid-turbocharger and sequential turbos.

How do each of these setups act as far as turbo lag and boost threshold?

Is e-boosting reliable? If so, how does it compare to other turbo setups?

 

[cindys_sn95]

david someone else will have to help with the turbo stuff, but here we go. besides decking the block to make it completely flat/true you can also use it to control quench or squish as some people call it. quench is where the flat part of the piston comes up to the flat part of the head and pushes the compresed mixture into the chamber for firing. ideal quench is .035 to .045. i normally try to plan out the deck height depending on head gasket thickness. if i am using a .038 gasket i will go for a .000 deck, if i am using a .018-.020 shim i will deck it to + .010 ect, ect..... hope this helps

 

[David.kinter]

Thank you Cindy.

So, with a .041" gasket size I'm fine with a zero deck clearance.

Why would you use a shim at all?

Moving on, I'm reading that a .35-.45 quench is ideal for an NA engine. There are some articles I'm reading that state for boosted applications a slightly higher quench is better. Why? What effect does it have on the engine? Are the tolerances too close for a boosted engine at .035"-.045" quench? I don't understand why boost would make a difference in how much quench is optimal.

 

[cindys_sn95]

yea, with a .041 gasket and .000 deck = perfect. with boost the quench can be opened up some because there is more air and fuel to deal with, and if it is to close you can get into detonation. if you are at those figures, you would just have to be careful with detonation depending on the amount of boost. oh yea, on the shim question.... that mostly relates to small block chebbies! :winks

 

[David.kinter]

Okay, I found my answer.

Now heres another question for you:

Lets say I wanted to run on the ragged edge with twin 80mm's. Would it be wise to open it up a bit?

 

[David.kinter]

And no, this isn't for a street car. I'd like to get serious into competition. It's going to take me 4-5 years to put the entire car together by my calculations and budget.

 

[cindys_sn95]

yes. that is going to open a lot of things!

 

[David.kinter]

Can you be more descriptive on what kind of things I'm going to need to look out for?