PREDATOR-Z

Don't know where to post this so here goes.

11.8 CR and 98 octane premium.
Is that enough octane to run daily on the steet without being plagued by detonation?

PREDATOR-Z

Planning on getting MTI 5.3 stage 2E (58cc).
Which will net me a 11.8 CR.

Now I need feedback as to whether 98 Octane premium is enough to run normally on the street and be safe from detonation

Here Regular is 95 Octane and Premium 98.

Slowhawk

iTrader: (12)

I use to run 11.4-1 on 93 octain and 30 degree's of timing..The Cam overlap also plays a role on compression.

Fireball

iTrader: (21)

are you sure you'll be at 11.8:1? How much are they going to mill off the 5.3L heads? I had .040 which I was told was 11.8:1...but I haven't CC'ed to verify.

I run 93 octane without any pinging

steve2001sh

Well, you can't go wrong with posting it here. I've heard of guys running 11:1 on 93 premium. You will be cutting it close. It also depends on your timing, the quality of your heads, and a million other things. I'm really not sure, but until somebody more qualified answers you, I'll say that it will be cutting it close.

steve2001sh

Your premium is 98?! Dang it! Tennessee sucks!

PREDATOR-Z

Well I e-mailed Jayson at MTI to find out for sure. It is the 5.3 Stage 2E (High CR) that they have on special for 1795 outright (No exchange)

He said they are 58cc which will be around 11.7>11.8:1 with graphite gaskets.

PREDATOR-Z

Cam is going to be X1 230/227 112lsa which has +4.5 degree of overlap

PREDATOR-Z

Heads: MTI 5.3 Stage 2E (58cc)
Cam X1 230/227 112lsa with +4.5 degree overlap

JZ'sTA

iTrader: (23)

You can run even more compression then that if you have the tune done correctly and timing pulled out. However I am sure you are asking the question because you want to run 28-30 degrees of timing (where most guys make best power) and at the same time have no knock.
You typed 98 octane. I have never seen this but if 98 is the correct number then you should be just fine.
If you ment 93 octand I wouldn't go much higher then 11.3 CR.

WILWAXU

iTrader: (6)

I have no problems with 93 octane. I don't think my compression ratio is that high.. and those heads should be close to the same as mine.

Give MTI a call.

badls1

iTrader: (1)

It aint fair you get 98 from the pump. Out here we get crappy 91. 95-96 would be fine.

PREDATOR-Z

According to the sticky table in this forum

58.27cc will yield 11.6:1 so I figured that a flat 58cc would be around 11.7>11.8:1

Was I wrong in my assumption?

You are running 5.7 stage 2E's and mine would be 5.3's (58cc).

What is your CC on your heads??

jrp

iTrader: (16)

from what i've learned dynamic compression will be a better determinant. FWIW im going to be around 11.6 for my new setup, will probably have to run a mix of race if im going to be able to run high timing with 91

PREDATOR-Z

I do not live in the US. Here gas is 95 Octane regular and 98 octane premium.
Wish it was like that in back home in TX.

WILWAXU

iTrader: (6)

I didn't CC my heads before install. Like I said above. Give the guys at MTI a call. I'm sure they can tell you right away what's best for your combo.

6.0vette

Just make sure you run colder plugs and close the gap to
.35-.40 and youll be fine.