Darth_V8r

iTrader: (4)

USA 93 octane and 8.73 dcr

Mickyinks

I think our 98ron here is the equivalent to usa 93 so ill stick with a .051 head gasket. What is the ideal number for dynamic?
Ill be at 8.76 with a .051 gasket

Darth_V8r

iTrader: (4)

8.73 is ideal for 93. Actually I only worry about it for low rpm operation. At high rpm, SCR takes over and 93 will tolerate 12:1. If you can find PatG thread torque coming out of my ears, read it. It's going to do a better job than I will highlighting how much better the torque curve gets as you approach 8.7. Even starting from 8.5.

Darth_V8r

iTrader: (4)

https://ls1tech.com/forums/generation-iii-internal-engine/481382-torque-coming-out-my-ears-cam-change.html

Call it assigned reading lol

Mickyinks

Thanx ill read it now,

Mickyinks

Good reading.... Im looking forward to the new cam, if ive got my head around it correctly, the last cam had dcr of 8,27. The new cam will be at 8.76, so i should pick up minimum 20rwtq with very very little lost in way of HP. Now where are those lifters lol

Darth_V8r

iTrader: (4)

Yup. Possibly it will reduce the peak rpm a bit. But dcr is the exact reason early in this thread that several people said they liked the smaller cam - the one you are swapping to

rkupon1

iTrader: (3)

Small cam club!!! Im in!

Mickyinks

Can anyone school me on CC volume. In my compression calculations im allowing for -5cc pistons but i dont think that includes anything for valve reliefs.
The pistons are dished 3.62in x .052in deep so volume is 1.81in radius x .052in depth = .54 . I presume tht equals -5.4cc
Then standard valve reliefs in a flat top piston is -4cc So -4cc + -5.4cc = -9.4cc ....... Is this correct?????????

spanks13

iTrader: (5)

The -5 is the volume of your valve reliefs

Mickyinks

So that doesnt include the dish?

Mickyinks

So in a flat top piston the valve reliefs are 5cc the id add 5.4cc dish minus .052in dish depth on valve reliefs ?????? If i said -10cc id be very close.... CORRECT?????
If my figures are rite the engine only had dynamic figures of 7.96
New head gasket figure would have to be .036 instead of .052... and that would give me .088 squish which isnt ideal..... Correct??????

spanks13

iTrader: (5)

Typically what I see is the piston spec gives you a total volume. Flat tops with reliefs are usually around -5cc. If there’s a dish it’ll give you total negative volume, and a dome is total positive volume.

Mickyinks

I have no piston specs!!!!!!
On JE piston web site all the flat top pistons do have -5cc reliefs
What im trying to work out is how many cc is the dish worth.
The dish measures 3.62in diameter x .052in deep.

bortous

What is your combustion chamber size in cc?

Mickyinks

They are 67cc.... Ive worked out the piston cc, they are 9cc so the engine had 11.58:1 static with a dynamic of 8.1
with a .051 head gasket ill have 11.58 static and 8.59 dynamic
With a .045 head gasket ill have 11.74 static and a dynamic of 8.71
With a .040 head gasket ill have 11.89 static and 8.81 dynamic

Darth_V8r

iTrader: (4)

Cool looking application, but you use the .006" lift valve events to calculate DCR, not the .050". That's why your dynamic is calculating such a high number.


Run the .045 head gasket. You want quench as tight as you can get it for detonation resistance.

Mickyinks

The engine builder supplied this pic after i asked what cc the heads were and what cc the pistons were... THOUGHTS????

Mickyinks

Thats what i told him , he said that low dynamic compression wont bleed torque

Mickyinks

Where did tune master post that pic Darth?