Stroker Advice

[jules325i]

what ill be using.
885 head
E Crankshaft
ross racing pistons 11:1 85mm (i hope)
"I" rods
schrick 288
vac hd valve springs
HD Rockers
Multi angle valve cut
port and polish.
Megasquirt (if i can find some in Australia that will tune it for me)


Well im going to order the ross racing pistons from IE, my question is if i order 10:8.1 by the time i have the head skimmed and possibly blocked decked, i will be around 11:1 is my thinking right, also with stock head gasket, or do i just order 11:1 Also ordering the schrick 288, is this engine going to ping like hell even once its tuned, ill be using 98 octane fuel at all times.


Does anyone know what the stroke the E crank has in combination with the "I" rods.

[jules325i]

what ill be using.
885 head
E Crankshaft
ross racing pistons 11:1 85mm (i hope)
"I" rods
schrick 288
vac hd valve springs
HD Rockers
Multi angle valve cut
port and polish.
Megasquirt (if i can find some in Australia that will tune it for me)
Not sure what injectors to run is there a 24lb option?


Well im going to order the ross racing pistons from IE, my question is if i order 10:8.1 by the time i have the head skimmed and possibly blocked decked, i will be around 11:1 is my thinking right, also with stock head gasket, or do i just order 11:1 Also ordering the schrick 288, is this engine going to ping like hell even once its tuned, ill be using 98 octane fuel at all times.


Does anyone know what the stroke the E crank has in combination with the "I" rods.

[digger]

what ill be using.
885 head
E Crankshaft
ross racing pistons 11:1 85mm (i hope)
"I" rods
schrick 288
vac hd valve springs
HD Rockers
Multi angle valve cut
port and polish.
Megasquirt (if i can find some in Australia that will tune it for me)


Well im going to order the ross racing pistons from IE, my question is if i order 10:8.1 by the time i have the head skimmed and possibly blocked decked, i will be around 11:1 is my thinking right, also with stock head gasket, or do i just order 11:1 Also ordering the schrick 288, is this engine going to ping like hell even once its tuned, ill be using 98 octane fuel at all times.


Does anyone know what the stroke the E crank has in combination with the "I" rods.

10.8 or 11:1 you wont notice the difference but it wont ping if it is tuned properly people usually use NGK BPR6ES plugs on higher comp m20's which is 1 heat range colder plug.

the eta crank has 81mm stroke no matter what rods you use.....

[Ray Smoodiver]

TIL why my Alpina pistons rattle when cold, probably the 291,000km too :D

I R stupid.

Carry on gents, I'm listening intently (and thinking 288/288 + 42mm throttles for winter project).

[jules325i]

10.8 or 11:1 you wont notice the difference but it wont ping if it is tuned properly people usually use NGK BPR6ES plugs on higher comp m20's which is 1 heat range colder plug.

the eta crank has 81mm stroke no matter what rods you use.....

I have a set of "e" Rods and a set of "I" rods which should I use, also I'm thinking of using the pink tops 21lb injectors they will be enough won't they

[SkiFree]

What Digger is saying is that the crank's stroke is the cranks stroke, irregardless of your rod length.

Perhaps you were asking what your displacement would be?

And as a side note, you might want to simply ask these kinds of questions to your engine builder or who your getting parts from, since its what they do for a living. (not that there's anything wrong with Digger's excellent advice, I just know that sometimes things can be related much easier on the phone or in person rather than a message board where things can easily be missed or misconstrued).

[jules325i]

Yes a very good idea I'll get in contact but you both can tell me which rod will give me greater displacement.

[digger]

Yes a very good idea I'll get in contact but you both can tell me which rod will give me greater displacement.

the rod DOES NOT affect displacement. the longer the rod means you use a smaller compression height on the piston so the piston sits at the correct position at the top of the block.

the piston compression height is the distance from the pin centreline to the deck of the piston.

a smaller compression height is better for stability contrary to what people might think. as long as the compression height is not so small to where you cant fit a decent ring pack in which can affect ring seal and oil control.

just use a 135mm rod and eta crank you have plenty of room to fit a good ring pack. speak to the piston people for specifics on size and type.

[jules325i]

the rod DOES NOT affect displacement. the longer the rod means you use a smaller compression height on the piston so the piston sits at the correct position at the top of the block.

the piston compression height is the distance from the pin centreline to the deck of the piston.

a smaller compression height is better for stability contrary to what people might think. as long as the compression height is not so small to where you cant fit a decent ring pack in which can affect ring seal and oil control.

just use a 135mm rod and eta crank you have plenty of room to fit a good ring pack. speak to the piston people for specifics on size and type.

Thanks mate very informative.

[CrazyJew89]

Oh, cool. An explanation of compression height. I had no idea what dimension that was from my reading in the other stroker threads. Thanks Digger.

[digger]

http://www.lunatipower.com/Tech/Pistons/CompressionHeight.aspx

[Ray Smoodiver]

May as well throw this question in here, what sort of squish is ideal for an M20?

[LJ851]

May as well throw this question in here, what sort of squish is ideal for an M20?

1mm is typically a good safe minimum number on most engines.

[digger]

May as well throw this question in here, what sort of squish is ideal for an M20?

1.00 to 1.25mm is fine, could go a little bit closer on a racenegine but on the angled squish band of the 885 it is more difficult to achieve. you would want good rods and light piston to go smaller. dont forget to allow for some piston rock

By my calculations with a 1.75mm head gasket (I remember hearing that 1.75mm OEM gaskets were NLA a few years back) the piston should be above the deck ~0.7mm. If you use a 2.05mm gasket it would be ~1.0mm above deck to achieve this.
Obviously you would measure deck height and mock it up to get it right as well as paying attention to piston to valve clearance. the more the head has been skimmed the closer everything gets to

[bradnic]

bumping a terrific thread for posterity. so much great info here!
thanks Digger