Vortecs,10:1CR,and 89 pump gas - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum

Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
lost password?   |   register now

LinkBack Thread Tools
  #1 (permalink)  
Old 02-03-2011, 07:10 PM
GMC boogie's Avatar
Last photo:
Join Date: Nov 2004
Location: Louisiana
Age: 51
Posts: 774
Wiki Edits: 0

Thanks: 5
Thanked 47 Times in 42 Posts
Vortecs,10:1CR,and 89 pump gas

Is anyone successfully running flat top pistons,good quench,Vortec heads,355 cubes,87-89 pump gas,and a 218-220ish duration at .050 cam with 108 LCA?

Without having to retard the timing?

Would like to run flat tops for the better compression but may have to go with a 12cc D dish for 9.4:1

Reply With Quote Quick reply to this message
Sponsored Links
  #2 (permalink)  
Old 02-04-2011, 05:57 AM
octanejunkie's Avatar
Registered Looser

Last journal entry: Background: why I am here
Last photo:
Join Date: Dec 2009
Location: Los Angeles, CA
Posts: 146
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The impossible dream perhaps?

I am running a very similar combo but am down in the 9.25:1 area with a 214/224 cam on a 112 LC, no quench to speak of. I have to run 91 octane. My initial timing is around 12 degrees, 10 if I want it not to ping, and my vac adv is limited to 10 degrees. I'm also running 2 steps colder plugs gapped to .045.

My engine was built with 10cc flat top pistons with a .020 taller pin height, putting them .020 deeper in the hole - wasn't my choice but it's done - quench distance is around .065 right now. Average measured deck height is .0276 and I'm running a .040-ish gasket with 64cc vortec 906 heads.

I am contemplating a head gasket swap to get me down to .040 quench which will also bump my static CR to 9.8 - not sure if this is going to help or hurt and may prove to be a lot of effort wasted if it doesn't net me any benefit from improving the quench.

From my experience tuning my build, you need to control your timing and temperature to keep it from pinging, and from what I have surmised, the only way to run lower octane fuel will be with EFI and electronic ignition/timing control. I can't put more than 32 degrees of timing into it without detonation on 91 octane at 9.25:1, and that's in normal driving conditions in So Cal, perhaps you could get away with what you are looking for in a much colder climate...

Hope this helps
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 02-04-2011, 09:17 AM
curtis73's Avatar
Hates: Liver. Loves: Diesel
Last wiki edit: How to find cheap parts
Last journal entry: Found an LQ9 today
Last photo:
Join Date: Dec 2005
Location: Carlisle, PA
Age: 43
Posts: 5,472
Wiki Edits: 16

Thanks: 31
Thanked 52 Times in 44 Posts
There might be something that needs a bit more tuning...

I'm running 906 heads with a 190 stat in my boat with a 196/206 cam, 9.55:1, and I run 87 octane all day with heavy loads. Of course, I don't have a vacuum advance, but its set up for 12 initial and 34-35 total. Never a single ping.

I find that with my vortec builds I can get away with almost one full point of compression with the same cam on low octane, and just over one full point with more cam (more duration AND overlap).

For instance - on a mild-cammed 8.5:1 350 (76cc heads) I was able to swap to vortecs (about 9.25:1) and keep the 87 octane.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 02-05-2011, 07:05 AM
Custom10's Avatar
my KARMA ran over my DOGMA

Last journal entry: SS
Last photo:
Join Date: May 2009
Posts: 1,137
Wiki Edits: 0

Thanks: 27
Thanked 58 Times in 51 Posts
The are most likely many guys running a flat top 355 with 64cc heads on the street with 87 octane but there overall setup may be allowing this, gears, cam and vehicle weight etc will factor in.

There seems to be a consensus that -12 or -18cc d dish pistons are the ones of choice for a 64cc headed street type motor with approx 9.5 final SCR. Keeping a good quench in the range of 0.035-0.045 with these set ups is also a common practice.

Your question leads me to believe that you may be in the same boat as I was last spring when I put together my 383 with -18cc hypers to keep things around that 9.5:1 with my vortec heads. At the time the machinist/builder who put together the short block asked me a very important question. He wanted to know what the motor will be installed in and what are the intentions for the truck in my case.

What it boiled down to was that going to dish pistons is the way to go for my daily driver and occasional tow rig. Thing is after all that I wished I would have went flat top and a bigger cam since I put limited mileage on the truck this summer anyhow. I could have lived with paying for premium and building the rest of the truck to suit since I put in a new 700R4 and a posi with new gears. Thats when I would could have moved into a higher stall, bigger cam and 4:11 gears.

IMO Making the move to flat tops has allot to do with the rest of the setup and what you will be using the mill for.

Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 02-05-2011, 09:05 AM
octanejunkie's Avatar
Registered Looser

Last journal entry: Background: why I am here
Last photo:
Join Date: Dec 2009
Location: Los Angeles, CA
Posts: 146
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Similar situation Custom10, my builder asked me a few questions and put 10cc pistons in knowing I would run 64cc vortecs, cam was my choice.

I opted for 3.42 gears as my original trans was a T350 w stock converter, but I sprung for a 700R4 last christmas with a 2300 rpm converter and have never been happier - I just wish I had 3.73 or 4.11s out back.

I think I can tune the ping out of my setup, and the few extra pennies at the pump to run premium has not been a huge issue - just not sure if going to 9.8:1 SC is going to be a good thing or not to get to an .040 quench
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 02-05-2011, 09:08 AM
The mobile view is crap
Last photo:
Join Date: Feb 2009
Location: Middle of the Mitten
Age: 32
Posts: 1,876
Wiki Edits: 0

Thanks: 194
Thanked 107 Times in 95 Posts
kb makes a piston that is a dish piston with a d shape cup. The design of the piston puts the dish on one side of the piston so you still get the flat top burn benefit, in a perfect world the fuel should be burnt before it leaves the flat part of the d shaped cup piston
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Please select your insurance company (Optional)


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Vortecs on 305 then to 350 American Muscle Engine 3 12-25-2009 08:09 AM
vortecs on a 400? 694X4 Introduce Yourself 1 10-02-2007 07:38 PM
350 L79 cam & vortecs? VEGA 3503508.5 Engine 11 05-22-2006 07:11 PM
When did they come out with the 350 Vortecs Ace_Spades307 Engine 4 11-26-2005 09:28 PM
Vortecs SBC-S-15 Hotrodding Basics 13 10-04-2004 12:34 PM

All times are GMT -6. The time now is 12:14 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.