 
     |
| 250 WHP Supernatural 3.4 Build (Page 15/47) |
|
unboundmo
|
DEC 04, 03:27 PM
|
|
| quote | Originally posted by La fiera:
Look closely. |
|
Would this be from a not balanced crank?
|
|
|
|
Daryl M
|
DEC 04, 04:03 PM
|
|
|
|
|
mender
|
DEC 04, 04:09 PM
|
|
| quote | Originally posted by unboundmo:
Am I wrong that when talking about octane ---- 87 - 112.... the higher the number, the more delayed in explosion?... not sure if my Dad was right but he always said the higher, the more junk is in the gas to delay the explosion.... so it would be a timing thing to fine tune a certain octane to a certain timing for maximum efficiency?... higher octane, the less advance the timing?
I run 91 with my built Fiero - set at 10*.. but I use 87 for my stock jEEP.. stock ecm setting.. whatever that is
****Can someone explain this?---- no guessing!****
|
|
Higher octane doesn't change the burn speed, it raises the fuel's auto-ignition point. That means it takes more temp/pressure to light off the mixture without an outside source (spark usually).
Proper timing is set for the engine's characteristics, not the fuel's. Run what the engine wants, both in timing and octane.
|
|
|
|
Blacktree
|
DEC 04, 05:10 PM
|
|
I see SBC rods in your future. 
|
|
|
|
turbo 3800
|
DEC 04, 06:19 PM
|
|
|
Did you blow the motor already? How many miles you get out of it?
|
|
|
|
unboundmo
|
DEC 04, 09:17 PM
|
|
This is great.. thanks Daryl.. and mender
----does anyone know if there is a guide / chart somewhere that shows what compression is for what range of octane?.. sorry La Fiera for interrupting your thread... some good advise though!
Anyway, My Fiero is running 9.25:1 compression -- Ross pistons
Edit to say----- I guess my Dad had it right, in a way.. I was wrong when I started talking about timing..[This message has been edited by unboundmo (edited 12-04-2017).]
|
|
|
|
unboundmo
|
DEC 04, 09:22 PM
|
|
|
|
|
unboundmo
|
DEC 04, 10:23 PM
|
|
So in research I've seen there are Many charts per octane / compression ratio to be optimum.. my stupidness 😜.. but then I ran into this picture and thought it would fit this thread
La Fiera --- talking back regarding that 2.8L.. and the cam.. how is your powerband with your config now.. 10.8:1 and lobe lift.. is the 3.4L have the same .512 lift?
Mine---- 9.25:1 with the 260cam which is 204*.. my powerband feels at 12-1500+/- pretty much - to 53-5500ish..+/- and will go to 6k
http://garage.grumpysperfor...pression-ratio.9074/[This message has been edited by unboundmo (edited 12-04-2017).]
|
|
|
|
unboundmo
|
DEC 04, 10:48 PM
|
|
112 octane with this chart is way up there in compression.. just a little overkill?.. where does one even purchase the additive to make it that octane? ..... >---rocket fuel----->
Per the chart and your compression.. I don't see any less than 100 octane to be safe?.. no knocking.. not sure if 93 will be okay?
 [This message has been edited by unboundmo (edited 12-04-2017).]
|
|
|
|
La fiera
|
DEC 05, 08:15 AM
|
|
| quote | Originally posted by turbo 3800:
Did you blow the motor already? How many miles you get out of it? |
|
No, the first time It bent a rod and I was just driving it normal. I checked the timing table and it was way too advance I made sure I checked everyting and the timing I sincerely forgot!
When I got home I can hear the rod noise! Not even 50 miles 
So I took it out and put new rods and crank. Also re adjusted the timing table and is all good now.
|
|
|
