unshrouding valves, and polishing combustion chambers

Ok.
Work and try it.

EFI Tends to Super Atomize fuel.
Good for Fuel economy and driveability.
Displaces Oxgen needed for HP And ET 1/4 mile attempts.
Solution is Bigger is better mentality.
Works on BBC.
Pontiac V8 Carb or EFI Air in side.
Both have unique Cylinder head ports and 2 different schools of thought used to make Torque and HP.
 
Let me rephrase that.
It can run leaner than the richest cylinder, by that I mean BBC are notorious for #8 cylinder running lean because it's the farthest from the runner, so your carb will be fat on the other 7 jetting to #8
computers calculates this, this is why they have you put o2 in passenger side pipe
There for allowing you to run the other 7 leaner than with a carb.
At least that's what I was told.
 
Nice thing is it can all be tweaked
With a chassis dyno, it will allow you to move fuel up or down so if it's lean in spots you just dial it up at whatever rpm you want.
 
Hi Tech is great.
Reading spark plugs is still done.
At least I still do.
Oh I still use my cheat sheet to verify

index.php
 

Attachments

  • Spark Plug Reading.jpg
    Spark Plug Reading.jpg
    215.7 KB · Views: 55
Last edited by a moderator:
how to go about getting the desired compression ratio?
matching the piston dish to the vortec combustion chamber and maximizing the quench area,
tends to reduce detonation, improve and speed up the combustion efficiency

26603d1139171792-piston-deck-measurement-clearance-squishband.jpg

attachment.php




if youve read a bunch of the threads on this web site your sure to eventually have considered theres,
more than one route to build any engine to allow it ,
to get to the desired combustion chamber,

or true compression ratio.in an ideal combo you'll want to minimize or avoid,
the use of a large dome as the piston dome tends to retard flame front propagation,
this generally mandates a bit more ignition advance and that might reduce power.
if you have a choice a flat top piston
and a small, open and shallow combustion chamber ,
that does not shroud the valve flow is preferred.
port flow rates are greatly effected by exhaust scavenging so maximizing the scavenging,
through carefully matching the max compression the fuel octane will tolerate,
and cam timing, and header design is critical to maximizing power.


http://garage.grumpysperformance.com/index.php?threads/dynamic-vs-static-compression.727/

https://www.summitracing.com/newsandevents/calcsandtools/compression-calculator

http://www.diamondracing.net/tools/

https://www.rbracing-rsr.com/compstaticcalc.html

most people will start out thinking about a flat top piston that at TDC is about at the block deck height.

but theres hundreds of different piston designs , some domed, some dished,
and theres a huge variation in combustion chamber and intake runner and valve sizes,
and port flow can vary from the restrictive BBC peanut port that just barely out flows the vortec sbc heads,
in stock form to bbc heads that easily flow well over 400 cfm.

deckx.jpg

piston%20down%20in%20hole%20at%20TDC.jpg

seems simple enough! your piston is at BDC and its rotated to TDC, the bore diameter times the stroke is the cylinder volume,
that volume is compressed into the cylinder heads combustion chamber .

lets say were dealing with a 454 BBC your 454 displacement divided by 8 cylinder is approximately, 56.75 cubic inches per cylinder volume
combustion chambers are generally measure in cc's theres
16.3871 cc's in a cubic inch
so 56.75 x 16.3871=roughly 930 cc's being compressed into a combustion chamber volume. which will generally fall in the 96cc-123cc combustion chamber volume
remember open and closed chamber heads on THE BBC.
rectvsoval.jpg


and yes the piston may or may not have valve notches that generally add 5cc-7cc more combustion chamber effective volume, ahh,
but theres a head gasket, between the block and heads, that can be anywhere from about .021-.060,
and the deck height and piston too deck height will be different and must be accurately
measured to do the calculations.
and of course theres DOMED pistons in dozens of configurations.

opench1.jpg

F26595.png

TYPICAL FLAT TOP PISTON WITH ONE VALVE RELIEF NOTCH


opench2.jpg

F26655.png

TYPICAL DISHED PISTON USED TO LOWER EFFECTIVE COMPRESSION


http://garage.grumpysperformance.co...in-height-compression-height.5064/#post-66240
peanutpl2.jpg



definition.jpg



pistonatbdc.jpg

pistonat%20tdc.jpg

http://garage.grumpysperformance.co...in-height-compression-height.5064/#post-66240
 
Last edited:





theres a whole lot of minor tips in these videos that you should know and use to help increase the power potential of any cylinder heads you buy and use.
 

Cylinder Head Tech: Airflow vs Power

Words And Photos: Richard Holdener When talk turns to cylinder heads, the very first thing that comes to mind is airflow. This stands to reason as airflow is a critical element in power production and cylinder heads are one of the key components that determine the airflow into and out …
www.streetmusclemag.com
www.streetmusclemag.com

http://www.lockhartmachine.ca/c-f-m-calculator.html

www.motortrend.com

How Much Power Can A Given Cylinder Head Support? - Hot Rod Magazine

Air Flow Research developed a formula that predicts a normally aspirated, four-stoked gasoline engine's power potential based on intake-system airflow. We found this formula quite accurate to determine how much power that a given cylinder head can support.
www.motortrend.com
www.motortrend.com

www.cartechbooks.com

Cylinder Head Math for Engine Performance

This in-depth guide covers Cylinder Head Math for Engine Performance. When discussing high-performance automotive engines, a specific set of math formulas are used to develop and design power plants to make more power at higher rpm levels and still survive.
www.cartechbooks.com
www.cartechbooks.com

Can cylinder head flow testing be an indicator of potential horsepower? | TorqStorm

By: Ray T. Bohacz: If you are reading this, it means you have progressed from being a person that no longer wants to guess but instead wants to know how to make horsepower in an engine. The title of this primer is the question I asked myself when I had my engine shop. I then
torqstorm.com
torqstorm.com

Stan Weiss' - Cylinder Head Flow Data at 28 Inches of Water -- DFW / FLW Flow Files for use with Engine Simulation Software

Cylinder Head Flow Data @ 28 Inches of Water -- DFW / FLW Flow Files for use with Engine Simulation Software
users.erols.com
 
Last edited:
Back
Top