11.0:1 comp with very small cam ???
Thread Starter
TECH Regular
Joined: Jul 2019
Posts: 421
Likes: 71
From: Tasmania Australia
11.0:1 comp with very small cam ??? Hi Could someone tell me if 11.0:1 SCR compression ok to run in my LS1 with my cam?
Its 216/228, 2.7 overlap .590 lift, 853 heads, currently it will be 10.34:1 SCR but I'd like to run a thinner head gasket to bump it up, I'll run on 98 ron octane which is same as your 93 aki in USA.
If 11.0:1 isn't any good for this cam I'll get a bigger one that is.
Its 216/228, 2.7 overlap .590 lift, 853 heads, currently it will be 10.34:1 SCR but I'd like to run a thinner head gasket to bump it up, I'll run on 98 ron octane which is same as your 93 aki in USA.
If 11.0:1 isn't any good for this cam I'll get a bigger one that is.
TECH Apprentice
Joined: Jan 2017
Posts: 333
Likes: 75
From: Sydney, Australia
I ran Higgins ported 241 with 11:1 compression with a comp 214/217 .600/.587 112+4 cam for 10 years. This is on Aussie pump 98. Made just under 400 rwhp through a restrictive exhaust on a few Aussie dyno which read a lot lower than US dynos. So no issues.
Last edited by Pulse Red; Feb 26, 2020 at 03:39 PM.
LS1Tech Sponsor
Joined: Jan 2008
Posts: 2,237
Likes: 1,527
From: Ohio, Georgia, Nevada, Texas
I understand what you're asking, smaller cams usually have higher dynamic compression. But there's so much more to it
To answer your question in a simple way, you have the same compression as an LS2 and an LS2 ran a much smaller cam
It comes down the valve events of that cam. And even then, you can manipulate those through the cam's timing to get it where you want it.
You need to run that specific cam in a dynamic compression calculator... or you can set it to where you have 180-200 ish degrees of cranking compression and should be good.
For the way you're thinking, you could go to a bigger cam, and have more problems than you would with that cam. It isn't the cam size, it's the intake valve closing point really.
To answer your question in a simple way, you have the same compression as an LS2 and an LS2 ran a much smaller cam
It comes down the valve events of that cam. And even then, you can manipulate those through the cam's timing to get it where you want it.
You need to run that specific cam in a dynamic compression calculator... or you can set it to where you have 180-200 ish degrees of cranking compression and should be good.
For the way you're thinking, you could go to a bigger cam, and have more problems than you would with that cam. It isn't the cam size, it's the intake valve closing point really.
Trending Topics
Thread Starter
TECH Regular
Joined: Jul 2019
Posts: 421
Likes: 71
From: Tasmania Australia
Thanks for that, it has +2 degrees advance, although it was a custom ground to my specs and they said they would grind it with no advance so it's an oddity to me, I checked and rechecked lots times and phoned them but +2 measures up most accurately with the specs on cam sheet.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?
Pouria Savadkouei
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
It's because the dyno's turn backwards down there...
Thread Starter
TECH Regular
Joined: Jul 2019
Posts: 421
Likes: 71
From: Tasmania Australia
Thanks, It shows IVC to be 38.5 ??? I measured it at 37.5 ?
Quote
"I ran Higgins ported 241 with 11:1 compression with a comp 214/217 .600/.587 112+4 cam for 10 years. This is on Aussie pump 98. Made just under 400 rwhp through a restrictive exhaust on a few Aussie dyno which read a lot lower than US dynos. So no issues."
Did you mean to say you verified this on a "few Aussie dynos", that's a lot of power for that duration, I have bit more duration and I am only expecting around 360 to 370 rwhp, in my freshly built LS1 with mildly ported heads in M6. It must be your Higgins heads helping out a lot.
Quote
"I ran Higgins ported 241 with 11:1 compression with a comp 214/217 .600/.587 112+4 cam for 10 years. This is on Aussie pump 98. Made just under 400 rwhp through a restrictive exhaust on a few Aussie dyno which read a lot lower than US dynos. So no issues."
Did you mean to say you verified this on a "few Aussie dynos", that's a lot of power for that duration, I have bit more duration and I am only expecting around 360 to 370 rwhp, in my freshly built LS1 with mildly ported heads in M6. It must be your Higgins heads helping out a lot.
Last edited by TimsLS1; Feb 27, 2020 at 02:17 PM.
Ok at that you are right at the limit for 93 octane US gasoline at 11.0 compression. If it makes you nervous, a 1 degree retard will get you breathing room and still be very torquey
Thread Starter
TECH Regular
Joined: Jul 2019
Posts: 421
Likes: 71
From: Tasmania Australia
That's good to know, I can only go 2 degree increments on my timing wheel if I retard from my current +2 possition to 0 to 0 my IVC ends up at 40 which seems much better for what I'm wanting but my EVO ends up being 41.5, is this still ok?
If doing this restricts exhaust side a bit I'm not concerned as I have too much on exhaust side anyway with my wide split and more porting on exhaust?
If doing this restricts exhaust side a bit I'm not concerned as I have too much on exhaust side anyway with my wide split and more porting on exhaust?
TECH Apprentice
Joined: Jan 2017
Posts: 333
Likes: 75
From: Sydney, Australia
Thanks, It shows IVC to be 38.5 ??? I measured it at 37.5 ?
Quote
"I ran Higgins ported 241 with 11:1 compression with a comp 214/217 .600/.587 112+4 cam for 10 years. This is on Aussie pump 98. Made just under 400 rwhp through a restrictive exhaust on a few Aussie dyno which read a lot lower than US dynos. So no issues.'
Did you mean to say you verified this one a few Aussie dynos, that's a lot of power for that duration, I have bit more duration and I am only expecting around 360 to 370 rwhp, in my freshly built LS1 with mildly ported heads in M6. It must be your Higgins heads helping out a lot.
Quote
"I ran Higgins ported 241 with 11:1 compression with a comp 214/217 .600/.587 112+4 cam for 10 years. This is on Aussie pump 98. Made just under 400 rwhp through a restrictive exhaust on a few Aussie dyno which read a lot lower than US dynos. So no issues.'
Did you mean to say you verified this one a few Aussie dynos, that's a lot of power for that duration, I have bit more duration and I am only expecting around 360 to 370 rwhp, in my freshly built LS1 with mildly ported heads in M6. It must be your Higgins heads helping out a lot.
One run was at a dyno day. Being so quiet (small exhaust, little overlap) it gave people quite the shock when it was reeled off that number and was higher than nearly all the other big cams that day (majority were around 370-380). No one believed it was a baby cam. Even the shop owner running the dyno.
Even a well known cam manufacturer refused to believe the duration based on the power and time at the track and said to get it measured when I replaced it. I did and it was actually smaller than I originally was told (I bought it as a secret shop cam with a duration of 216/220).
It was a great combo and ran very hard on the street but the combo was built on old lobes and things have changed a lot since those days.
Last edited by Pulse Red; Feb 27, 2020 at 03:00 PM.
Thread Starter
TECH Regular
Joined: Jul 2019
Posts: 421
Likes: 71
From: Tasmania Australia
Really impressive!!! Higgins knows what he's doing, he knows not to port too much and loose low to mid range he ports too 42 mm on intake, and you were still able to make good top end. There are a few on here who have made 400 rwhp with 216 or less cam in LS1 but not many.Do you remember where peak HP was at?
Last edited by TimsLS1; Feb 27, 2020 at 02:51 PM.
TECH Apprentice
Joined: Jan 2017
Posts: 333
Likes: 75
From: Sydney, Australia
I would be one of those on LS1.com.au, I was quite a prolific poster on there. One of the tuners was another who had good results from a 216/220 back in the day.
I believe the Higgins heads are the key. The man knows his stuff. That and a good tune.
Thread Starter
TECH Regular
Joined: Jul 2019
Posts: 421
Likes: 71
From: Tasmania Australia
I'm learning slowly it's best to use valve events, I've been looking at lots of LS1 cams lately with 216 intake duration and the IVCs vary from 37.5 to 40 (approx), your cam might have been bit bigger than you thought.
TECH Apprentice
Joined: Jan 2017
Posts: 333
Likes: 75
From: Sydney, Australia
Nope, it was measured by Cam Tech after it was pulled out to confirm exactly what it was since it was a "secret" shop cam.
Originally Posted by TimsLS1
I'm learning slowly it's best to use valve events, I've been looking at lots of LS1 cams lately with 216 intake duration and the IVCs vary from 37.5 to 40 (approx), your cam might have been bit bigger than you thought.
Your 41.5 evo is late but at 11:1, it is not insanely late. Will just not carry power as well past peak.