10.9 CR with 91 octane? Issues?
Burning Brakes
Joined: Apr 2009
Posts: 946
Likes: 2
Ultimately the answer depends on your tune (and how aggressive the timing is set -- might be too much for 91 and 10.9:1). I plan on running a 10.5 or 11:1 daily driver on pump gas, but do my own tuning and have 93 octane here.
Just get it retuned for the new CR and you should be fine.
Just get it retuned for the new CR and you should be fine.
Thread Starter
Safety Car
Joined: Jun 2004
Posts: 4,983
Likes: 391
From: Stoney Creek Ontario
Kinda thought so, even though I've heard otherwise, I figured it's in the tune... didn't plan on going more than a Z06 head with my cam swap, but came across a pretty good deal on some 61.9 CC ported heads....
we can get 93 octane as well, but sometimes I end up with 91 in a pinch...
we can get 93 octane as well, but sometimes I end up with 91 in a pinch...
Le Mans Master
Joined: Apr 2005
Posts: 8,077
Likes: 4
From: Scarborough ONTARIO
Dan, depends on tune ofcourse, with stock timing why not. my C4 383 has 11.1:1 and use only 91 octane and on top of it i used to use 75-150 shot of nitrous ofcourse pull 1 deg of timing for every 50 shot.
U would not have any problem, call russ k he himself tunes cars and he owns a garage, BTW he is the most senior tuner member on HP tuner forum.
U would not have any problem, call russ k he himself tunes cars and he owns a garage, BTW he is the most senior tuner member on HP tuner forum.
Thread Starter
Safety Car
Joined: Jun 2004
Posts: 4,983
Likes: 391
From: Stoney Creek Ontario
Thanks, Sami, you know the heads I'm thinking of.. 
..... I sent Russ a pm the other day, after we talked, but haven't heard back yet... pm me his phone number if you have it...
We have an '88 Camaro, small block TPI with about the same CR no issues either......
..... I sent Russ a pm the other day, after we talked, but haven't heard back yet... pm me his phone number if you have it...We have an '88 Camaro, small block TPI with about the same CR no issues either......
Burning Brakes
Joined: Nov 2006
Posts: 1,071
Likes: 0
From: Goose Creek SC
Static Compression isn't directly related to the grade of gas you need. It's the Dynamic compression ratio (DCR) that determines that. DCR is based on the compression of your motor, size of your motor, and intake valve closing angle. Typically, larger cams close the intake valve later and thus cause the DCR to lower. So basically, without knowing your cam specs, the answer is not truly known.
Thread Starter
Safety Car
Joined: Jun 2004
Posts: 4,983
Likes: 391
From: Stoney Creek Ontario
Static Compression isn't directly related to the grade of gas you need. It's the Dynamic compression ratio (DCR) that determines that. DCR is based on the compression of your motor, size of your motor, and intake valve closing angle. Typically, larger cams close the intake valve later and thus cause the DCR to lower. So basically, without knowing your cam specs, the answer is not truly known.
Actually, I have a new Z06 cam, pulling the engine down to change some bad lifters, so doing a few minor up-grades at the same time.. don't want to go too wild though.. but I have a set of 61.9CC heads I'd like to use... otherwise, I'll just go stock Z06 heads...
Le Mans Master
Joined: Apr 2005
Posts: 8,077
Likes: 4
From: Scarborough ONTARIO
Dan using stock Z06 cam would be little waste using with CNC ported Lpe 243 heads, i have a nice (BNIB) 228/232 .585/.595 113 LSA cam, i choose this cam because this is still to mild side, not really big, and it perfectly matched with this head.
Notice u have a 2.73 gears, so upgrade those gears with stock 3.42 they sell for 400-700 all day long, u should do this first, gears are biggest bang trust me.
Give me a call or we will meet somewhere half way, reason iam selling, coz would like to beefed up drivetrain, new clutch, 410/3.90 gears and hardened drivetrain parts and suspension, and next year would do again H/C package, money is tight cant do alltogether.
Notice u have a 2.73 gears, so upgrade those gears with stock 3.42 they sell for 400-700 all day long, u should do this first, gears are biggest bang trust me.
Give me a call or we will meet somewhere half way, reason iam selling, coz would like to beefed up drivetrain, new clutch, 410/3.90 gears and hardened drivetrain parts and suspension, and next year would do again H/C package, money is tight cant do alltogether.
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