engine planning

[Chryco Psycho]

Planning an engine
 There are a lot of considerations when looking at building an engine ,
first is the block itself , later castings are rumored to have thinner walls , this IS not
true the block may have less nickle content & be slightly less hard , , any performance build
should be sonic checked to check thickness, I have seen late modle blocks with 3/8 " cylinder
walls & I have seen blocks that left the factory to thin at stock bore
 you want to check the brgs as the crank is removed to check for signs that the bore may not
be straight through the mains  this can be fixed by align boring the block , also studs can be
 used to retain the mains caps in higher output builds, the block will need to be honed if studs
 are used
to equalize compression you should have the block decked square to the crank center line as well
the factory was not overly accurate with this you also need to check the piston to deck clearance
 as most blocks are higher than the spec & any piston may lose .1 -.2 compresson ratio due to
excessive deck height
 in the big block you may want to bore the oil passages in the big blocks to accept the 1/2 Hemi pick up tube to
help oiling, although I have never had a problem with the stock oiling system as long as the oil
pan  is baffled & has adequate capacity , I always use a new oil pump , be careful not use use a
 high volume pump with a stock 5-6 qt oil pan , I also use a windage tray in every engine , it
will free up HP by keeping oil off the crank & helps keep the oil in the pan to prevent starvation

 the next consideration is the crank itself , there are a nuber of choices , the factory offered
Cast or Steel cranks , the cast are plenty strong & will take 500 + HP in a big block but they
require  external balancing in most cases which makes getting correct SFI spec [race] dampers &
flywheels difficult
steel cranks will handle more power & are internally balanced with the exception of the HP 440
in 70-71 which had the heavier 6 pack rod , the oil holes should  be chamfered as well
 the strokers cranks are very popular now , by increasing the distance from the main CL to the
rod throw CL this will push the piston both higher in the bore & pull it lower , this increases
the CI displacement , the pistons are very tall in Mopars so the piston can be made shorter
to help accomadate this , the brgs are important as well , I prefer to use a full groove main brg
these allow more oil to get to the bottom brg where the load is on the crank
 
 Pistons are the next consideration , there are 3 types cast , hyperutectic & forged
almost all Mopars had cast pistons from the factory , these are adequate for most applications
, I will not use Hyperutectic pistons , they are too brittle & are just an expensive cast piston
they can fail & distroy a block & more , generally  doing a rebuild I use forged pistons , they
may be overkill but if you want to swap a cam & heads & make more power at leaast you will not
have to rebuild the bottom end again. strokers require custom pistons generally shorter & lighter
 the pistons are very tall in Mopars so the piston can be made shorter to help accomadate this ,
the popular 451 stroker using the 440 crank in a 400 low deck B block lowers the rotating mass
by almost 7 lbs, you also have top decide exactly how much compression you want , most engines
will perform best on pump gas if the compression is held to just under 10:1 , how ever head &
cam design can affect the actual workable street compression , more compression will increase
power but you generally wiull need to run better fuels to do this , in racing this is no problem
 but on the street it generally becomes a pain

 Con rods , you must use new rod bolts & have the the rods machined & checked for straigtness ,
bushing the rods & using full floating pins is overkill & can lead to failures if the retainer
clips work out of the piston & the pin slides over into the cylinder bore , the rods are now
30  + years old often you can buy new I beam rods for as little as 2x the cost of the machining
& new rod bolts definatly worth considering also , the other option are H beam rod which are a
 lot stronger & lighter . Back to strokers any time you increase stroke if you maintain the
same rod length you lose Rod Ratio , no one discusses rod ratio , rod ratio is calculated by
dividing the stroke into the rod length , Mopars generally had good rod ratios in the 1.7-1.8
range , as the rod ratio drops torque output is lost due to reduced dwell time for the piston
at TDC & also durability is reduced, this is due to a higher angle between the con rod & bore
which increases side loading of the piston & cylinder wall
Back to strokers more CI will not nessisarily increase power if rod reatio is lost so you need
 to use a longer rod  as well , the 451 is ideal as it maintains the 440 stroke & rod length
creating the stoke rod ratio of 1.8 , the piston is made much shorter to acommodate this you
can do the same with the 440 block by going to a 4.15 stroker crank & using the Eagle 7.1" long
 con rod this creates a 1.71 rod ratio ,  if you want to go to bigger CI you either need a
higher deck block or the rod ratio will suffer
 it is worth the investment of having the rotating assembly balanced as the factory bablncing was
not great & with differnt parts being used the balancing maybe off off even more , this will free
up HP & extend brg life having the engine balanced properly
this cover most of the short block with the exception of the cam itself , the actual grind needs
to be carefully picked but you do have the choice of hyd  , solid or Roller cam this was covered
 in greater detail  in the earlier cam article but hyd offers maintainence free operation but
sacrifices some power , solid generally will run close to $1000 more & you have to adjust the
valves yearly or less but wil increase power solids & hyd cams are limited to 4000rpm power range
 so you need to decide exactly where you want the 4000 RPM window to be , 1000-5000 or 4000-8000
RPM , lastly roller which offers the maximum power & a wide powerband of closer to 5000 rpm but you
add another $100 or so to the cost over a solid lifter cam . with higher RPM better parts are
needed all through the engine to reduse the possibility of failure so the cost generally rises
as the RPM range is increased
 
 

[Chryco Psycho]

 More suggestions

Engine building Checklist
 there are a Lot of factors to decide when building an engine
 First get a budget together , engines can cost a LOT of money
-
 Second You need to first determine what the realistic use of the engine is , Cruzin , Street fighter ,
 Race .What is the  Rpm Range you need to work best with the intended use , this is the biggest factor in choosing
cams , intakes , heads & torque converters [if automatic ] so everything will work together & make the best
& most effecient power where you want it

Third determine What best suits the needs , Small block , big block, Hemi etc , depending what body you have
some can be difficult or impossible to even fit into the car , so the first choice is the basic engine family ,
Hemi [by far the most costly to build]Big block , small block , 6 , or 4 cylinder , old school with Carbs or
 modern with Computor & EFI

Fourth you need to determine what fuel you will use , using different fuels will affect the compression ratio
that is feasable to use & may affect the systems used with the engine ,Alcohol needs 14:1 compression
race engine often run 12:1 or more , on the other hand a forced induction engine often needs approx 8:1
compression but may still require special fuel

 When building an engine I refuse to cut corners in the bottom end / short block , often after an engine is
 built the owner may get bored with it & want more power from it or it may get transplanted into another car ,
spending a few extra $$ the first time will allow for future up grades to the engine instead of rebuilding
entirely & it cannot hurt durability to over build
 
Generally any rebuild I do includes forged pistons , new rod bolts, Michigan 77 brgs, balanced rotating assy
new oil pump , windage tray , blueprinting of the short block , equalized rod length [as much as possible ]
block decks trued to crank centerline , true roller timing chain , degreed cam CL , machined crank & block
to correct tolerances
 Having said that there are still a lot of decisions to be made
-the crank can be Cast which is generally good to 500 hp in a big block but can cause balancing issues or
flywheel availability porblems or forged cranks which are generally internal balanced except for the 6 pack
 the forged cranks will take more power as well   , or even  billet for maximum strength & much larger strokes of
3/4" or more in a big block  , Cranks can be tailored for stock stroke or a strokers which increase CI displacement
- if a stroker is being built some pistons are readily availble off the shelf other will have to be custom
made to get the exact compression or ci displacement needed
- the next decision is connecting rods , you can use stock rods , they are very strong or aftermarket in a
variety of lengths , designs - stock I beam or performance H beam & materials for use with normal stroke or
stroker combos
- windage trays & crank scrapers can also be added for better oil control widage trays restrict the amount of
effect the spinning crank has on the oil in the oil panas the crank can lift the oil off the bottom of the pan
at high RPM  , & a crank scraper will cut the excess oil off the spinning crank as a crank can suspend over
 1 qt of oil on itself at high rpm , the scraper reduces the weight of the crank & keeps the oil where it is
needed in the bottom of the pan  the oil system should also be addressed with both higher pressure & or volume
 oil pumps available & larger oil pan capacity as well, which is a must with high volume oil pumps 
- If very high valve spring pressures are present it may be worth looking at either gear drives or belt drives
instead of a timing chain
- the Main caps can be replaced with billet , cross drilled in a big block or even use a stud girdle for added
 strength but for most engines stock main caps are just fine , also avaliable are Main stud kits to replace
the factory bolts , main studs should be used for increased strength & stud girdles for the max increase in
strength short of upgrading the block
- The block itself can become an issue as well for high power engines there are a lot of choices available
from R3 & mega blocks from Mopar to full Alum blocks easily capable of 2200+ HP with a reduction in weight
as a bonus 
- next we get into the top end of the engine , the heads are a Huge decision Iron or alum
if Iron -stock or aftermarket ?, the iron head offer a Lot of advantages , cheaper cost , head gaskets are
cheap & easy to get , the heads retain more heat which =s more power , most use stock rocker gear ,
 but the disadvantages include weight & much harder to repair
 alum - offers lighter weight , repair ability , more chioces but generally have to be checked for machining
 quality before bolting them on , because alum expands far faster then iron you will need special Cometic
gaskets to allow the head to expand without tearing the gaskets , most require special head bolts & a lot
require special intakes & rockers to be used , you must also increase compression by close to 1 point to
allow  for extra heat loss to alum in the cylinder , so for example if a 9.8:1 engine will run on 93 octane
fuel without detonation you can increase the compression to approx 10.5:1 or higher with an alum head & still
use 93 octane fuel. Other consideration are the flow of the head , more flow Doesn`t nessisary = more power
a cylinder head with very large ports & high flow May be very sluggish at low - mid RPM so a head must be
carefully chosen to match the engine being built , the same is true with valve sizes , bigger valve do not
nessisarily make more power especially on lower rpm & smaller engines. Generally some careful porting of
virtually  any cylinder head will net gains as well unless the head comes with very large ports or is  CNC
 ported as delivered
- Exhaust is a factor as well , if you want the engine to look stock it is totally possible & still get a
lot more power from it with careful porting & cam selection to make it work , if you are using headers
you have to be careful on selecting the correct the right tube size to maximize velocity & scavanging
at the head & the size & quality of the exhuast pipe i scritical as well
- the intake is equally important it has to be able to match the flow of the heads & exhaust & match the
 powerband of the cam & the  RPM range desired for the engine combination . Dual planes are designed for
lower RPM while single planes are for higher RPM
- Carbs are just as important you have more choices than ever & the quality is getting better too , you
 can get multiple carb intakes with 6 packs or 2-4bbls , inline , crossram etc , you have to choose a carb
with the correct CFM to match the flow of the engine , generally 2x the CI is a good starting point , I have
witness as much as 60+ hp gain just from a carb change
- Next comes the cam choice with cams available in base Hydrualic , solid , Hyd roller & solid roller grinds
each step up costs more $$ though , any cam other than Hyd will require the additional cost of adjustable
rocker arms & pushrods & any roller cam needs expensive lifters as well
-  even Valve covers have to be considered it may seem like a simple choice But the very cool looking Cast
aluminum covers can be a problem , Most Mopar heads do not have a machined surface for the valve cover &
are left as cast , the reason Mopar used steel / tin covers is because they will flex & conform to an uneven
head surface  & are easily sealed , the cast alum covers will not conform & can be a nightmare to get sealed
 up , I have even seen 2or3 gaskets used & or the corners broken off the cover trying to seal them up , a
few weeks ago I spent 4 hours & went trough 5 gaskets trying to seal 1 cover 

[70RAGTOPR/T]

Chryco.....Thanks for writing this post.  Now I have instructions to take to my engine builder.  It also, gives me a checklist that I can printout have work from. 

[Chryco Psycho]

you are welcome 

[mickey]

Hi, i'am a new member and i just wanted to say a big thank you, for providing such a great site, iam having a blast reading all the post and being a mopar nut, i quess you can say iam hooked on this site.
To all involved and to those who post such great info as yourself keep up the good work.

[Chryco Psycho]

Glad We can hELP OUT !!