Engine Upgrade and Vortec questions....
Thread Starter
Racer
Joined: Feb 2006
Posts: 480
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From: Springfield MO
Engine Upgrade and Vortec questions....
Ok, im planning on buying the vortec head kit from Scoggin-Dickey but i have a few questions.
1980 l82 with Hooker SC side pipes and q-jet
1: what kit should i buy? http://www.sdparts.com/categories/en...dHeadKits.aspx
Im keeping my stock l82 low end, im just changing the heads and intake?
2: with my stock low end, any guesses on how much power i will be making?
3: I want to keep my q-jet but is that a bad idea? (i have had no problems with the Q at all) Im pretty sure it will fit under stock hood with the rpm air gap and a drop base but i might upgrade to the l88 hood.
1980 l82 with Hooker SC side pipes and q-jet
1: what kit should i buy? http://www.sdparts.com/categories/en...dHeadKits.aspx
Im keeping my stock l82 low end, im just changing the heads and intake?
2: with my stock low end, any guesses on how much power i will be making?
3: I want to keep my q-jet but is that a bad idea? (i have had no problems with the Q at all) Im pretty sure it will fit under stock hood with the rpm air gap and a drop base but i might upgrade to the l88 hood.
Drifting
Joined: Nov 2005
Posts: 1,601
Likes: 4
From: Texas
the Stock L31 350 in '96 up Silverado's put out 330hp... with a pretty
lame .420 lift cam.. a testament to the good design of the heads.
I'd re-cam the L82 and strap on a C&S or Race Demon carb...
Stock Comp Ratio on the L31 was 9.6:1...headers if you don't have'em..
lame .420 lift cam.. a testament to the good design of the heads.
I'd re-cam the L82 and strap on a C&S or Race Demon carb...
Stock Comp Ratio on the L31 was 9.6:1...headers if you don't have'em..
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
There's no reason to change the heads and intake without changing the cam. Note that flow on the stock Vortecs goes flat right around .450 lift...so there's no reason to go any further on the cam.
I'm traveling and so don't have my manuals in front of me - but if you're changing from a 76cc to head to the Vortec at 64cc this is an increase of 1 pt in compression.
The RPM intake is really only needed if you're turning REGULARLY over 5500 RPM. I'd go with the stock Vortecs and the Performer intake - along with High Energy-type cam in the .450 lift range.
I'd estimate power at about 330 - 350HP at the flywheel depdending on the cam selected.
I'm traveling and so don't have my manuals in front of me - but if you're changing from a 76cc to head to the Vortec at 64cc this is an increase of 1 pt in compression.
The RPM intake is really only needed if you're turning REGULARLY over 5500 RPM. I'd go with the stock Vortecs and the Performer intake - along with High Energy-type cam in the .450 lift range.
I'd estimate power at about 330 - 350HP at the flywheel depdending on the cam selected.
Drifting
Joined: Nov 2005
Posts: 1,601
Likes: 4
From: Texas
Vortec L31 Flow Data
.100 lift..70/49
.200 lift..139/105
.300 lift..190/137
.400 lift..227/151
.500 lift..239/160
.600 lift..229/162
Perhaps you're thinking about Double Humps falling flat..flow wise at
.450.... I'd lift from .525 to .560... At a theoretic average of 2 horsepower for every 1cfm of flow you'd be giving away 24hp if you stopped at .450 lift..
Reher/Morrison Racing suggest when chosing a cyclinder head
that you concern yourself with CFM/flow of Peak lift and .100 below
peak lift as this is where your valves will spend a majority of their
time. To position the valves near the heads peak flow in a maximum
effort engine you spec your cam's peak lift slightly above peak flow.
Stock Double Humps do have a limited CFM flow...there's just not
any appreciable increase in CFM at .500 & .600 in stock configuration.
.100 lift..70/49
.200 lift..139/105
.300 lift..190/137
.400 lift..227/151
.500 lift..239/160
.600 lift..229/162
Perhaps you're thinking about Double Humps falling flat..flow wise at
.450.... I'd lift from .525 to .560... At a theoretic average of 2 horsepower for every 1cfm of flow you'd be giving away 24hp if you stopped at .450 lift..
Reher/Morrison Racing suggest when chosing a cyclinder head
that you concern yourself with CFM/flow of Peak lift and .100 below
peak lift as this is where your valves will spend a majority of their
time. To position the valves near the heads peak flow in a maximum
effort engine you spec your cam's peak lift slightly above peak flow.
Stock Double Humps do have a limited CFM flow...there's just not
any appreciable increase in CFM at .500 & .600 in stock configuration.
Race Director
Joined: Jan 2003
Posts: 15,176
Likes: 88
From: State of Confusion
Ok, im planning on buying the vortec head kit from Scoggin-Dickey but i have a few questions.
1980 l82 with Hooker SC side pipes and q-jet
1: what kit should i buy? http://www.sdparts.com/categories/en...dHeadKits.aspx
Im keeping my stock l82 low end, im just changing the heads and intake?
2: with my stock low end, any guesses on how much power i will be making?
3: I want to keep my q-jet but is that a bad idea? (i have had no problems with the Q at all) Im pretty sure it will fit under stock hood with the rpm air gap and a drop base but i might upgrade to the l88 hood.
1980 l82 with Hooker SC side pipes and q-jet
1: what kit should i buy? http://www.sdparts.com/categories/en...dHeadKits.aspx
Im keeping my stock l82 low end, im just changing the heads and intake?
2: with my stock low end, any guesses on how much power i will be making?
3: I want to keep my q-jet but is that a bad idea? (i have had no problems with the Q at all) Im pretty sure it will fit under stock hood with the rpm air gap and a drop base but i might upgrade to the l88 hood.
you might want to ask-around the Forum to see how-wrong I am.....
As-stated above, heads without a better cam won't provide nearly as-much power as is possible, just-as a cam-swap w/o switching heads isn't optimal:
vortec-heads with a decent mid-range cam (something-like CompCams' 268H ? ) would make good power & torque below 5500 RPM, return better'n-average MPG, and have civil road-manners, too.
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
Keep the Q-jet if its in good shape it will flow plenty of air for a hydraulic cam 350, edelbrocks rpm airgap manifold that fits
vortec heads is a square flange manifold # EDL-7516, to use your Q-jet you would have to use the low rise performer vortec # EDL-2116 or
look for another manifold brand. I would agree with the rest if your
going to pull your engine down far enough to change heads buy
a more modern high lift cam, and go with the highlift version of
scoggins vortech heads. This lunati Cam/Lifters would give you the right amount of duration with good lift LUN-60103LK. it would require the high lift vortech
heads. the standard head is only good to around .480 lift
www.summitracing.com
vortec heads is a square flange manifold # EDL-7516, to use your Q-jet you would have to use the low rise performer vortec # EDL-2116 or
look for another manifold brand. I would agree with the rest if your
going to pull your engine down far enough to change heads buy
a more modern high lift cam, and go with the highlift version of
scoggins vortech heads. This lunati Cam/Lifters would give you the right amount of duration with good lift LUN-60103LK. it would require the high lift vortech
heads. the standard head is only good to around .480 lift
www.summitracing.com
Last edited by Little Mouse; Sep 18, 2007 at 10:13 PM.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Not sure where those numbers came from; mine were from the Car Craft Cylinder Head Database before it went TU and were clear that there wasn't much left after about .450-.475. Always debateable 
Very interesting note regarding cam selection - I'll have to think about that for a bit.
Completely agree regarding the camel humps unless huge investments are made in porting.
Very interesting note regarding cam selection - I'll have to think about that for a bit.
Completely agree regarding the camel humps unless huge investments are made in porting.
Drifting
Joined: Nov 2005
Posts: 1,601
Likes: 4
From: Texas
http://purplesagetradingpost.com/sum...Brodix%20IK180
or
http://users.erols.com/srweiss/tablehdc.htm#Chevy
2 sites are listing similar flow data for the Vortec L31's...
or
http://users.erols.com/srweiss/tablehdc.htm#Chevy
2 sites are listing similar flow data for the Vortec L31's...
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Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
http://purplesagetradingpost.com/sum...Brodix%20IK180
or
http://users.erols.com/srweiss/tablehdc.htm#Chevy
2 sites are listing similar flow data for the Vortec L31's...
or
http://users.erols.com/srweiss/tablehdc.htm#Chevy
2 sites are listing similar flow data for the Vortec L31's...
BUT - good thoughts and maybe I need to re-examine. I've got a buddy with a set of stock Vortecs that has been dyno'd - I'll see if he's willing to do a cam/spring swap (free machining by me
) and see what we get.
Race Director
Joined: Oct 2000
Posts: 15,048
Likes: 79
From: central FL, near the beach.
i like the stock L82 cam. not the best, but it passes the 100,000 durabilty GM requires. Works with the cheapest vortecs- no mods at all, not even springs!
Donny in C2 is running 13.47 @ 104 w/ similar stock cam.
It will work well with the higher CR of the vortecs.
Still, i'd change the timing chain!
Donny in C2 is running 13.47 @ 104 w/ similar stock cam.
It will work well with the higher CR of the vortecs.
Still, i'd change the timing chain!
Last edited by Matt Gruber; Sep 19, 2007 at 07:33 AM.
Le Mans Master
Joined: Mar 2004
Posts: 7,500
Likes: 1,508
From: Little Rock AR
The Vortecs are good entry level heads and work well with the L-82 cam. You can be at 10.4 C/R with the thinnest steel shim head gasket, 64cc chambers and a stock L-82 bottom end. The engine will idle fairly well and pulls hard at the top end. Very reliable too. GM still sells this cam. I think it is also used in the 290 HP crate engine. You would have more compression than that one has with your combination. Not a lopey big block by any means but good for some applications.
-Mark.
Not a lopey big block by any means but good for some applications. -Mark.
Drifting
Joined: Nov 2005
Posts: 1,601
Likes: 4
From: Texas
Vortecs are on the 350HO... the 290 has 1st Gen heads.. Vortec Heads are on one of the General's Circle Track crate motors for Dirt Track racing..the second and final Circle Track crate motor has the 210cc Fast Burns.
The L31 350 Vortec Engine will make 440hp with a cam change and
minimal preparation. The LT4 Hot Cam.. sold by GM, lifts with reliability
and longevity to .525.... the LT4 Hot Cam springs are std. on the ZZ4
and are very inexpensive... about $40 per set at Pace Performance.
The L31 350 Vortec Engine will make 440hp with a cam change and
minimal preparation. The LT4 Hot Cam.. sold by GM, lifts with reliability
and longevity to .525.... the LT4 Hot Cam springs are std. on the ZZ4
and are very inexpensive... about $40 per set at Pace Performance.
Last edited by KyleDallas; Sep 19, 2007 at 09:56 AM.
Le Mans Master
Joined: Mar 2004
Posts: 7,500
Likes: 1,508
From: Little Rock AR
It is an expensive upgrade to add a roller cam to an old school flat tappet block. I doubt that is in the budget here.
-Mark.
Drifting
Joined: Nov 2005
Posts: 1,601
Likes: 4
From: Texas
Check my quote...Never said the Hot Cam was std. on the ZZ4... said the Hot Cam springs were std...they are GM part #12495494
here's the proof:
http://paceperformance.com/index.asp...D&ProdID=24732
Drifting
Joined: Nov 2005
Posts: 1,601
Likes: 4
From: Texas
Engle Cams part #21046-H is a Hydraulic Flat tappet Cam
230dur @ .050
110 LSA
stock lift is .489
I'd run this cam with 1.6 rockers instead of the stock 1.5's...this would
give you a corrected lift of .522. I'd run this cam with the LT4 Hot Cam springs... on pocket ported Vortec L31's with headers. Shave the L31 heads to bring compression into the 9.4 to 10.00 compression range.
Cheap good flowing heads, cheap good springs, cheap good Hydraulic
Cam...hell of a good upgrade on a budget.
230dur @ .050
110 LSA
stock lift is .489
I'd run this cam with 1.6 rockers instead of the stock 1.5's...this would
give you a corrected lift of .522. I'd run this cam with the LT4 Hot Cam springs... on pocket ported Vortec L31's with headers. Shave the L31 heads to bring compression into the 9.4 to 10.00 compression range.
Cheap good flowing heads, cheap good springs, cheap good Hydraulic
Cam...hell of a good upgrade on a budget.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
If your position is that at a ~1HP/CID build level that extra lift is worth 24HP, then I'll 
right back 
IMHO I think you're building unrealistic HP expectations based on my experience given a stock L82 lower end, and going the route your offering doesn't make for a very streetable engine.
right back IMHO I think you're building unrealistic HP expectations based on my experience given a stock L82 lower end, and going the route your offering doesn't make for a very streetable engine.
Last edited by billla; Sep 21, 2007 at 12:19 PM.
Drifting
Joined: Nov 2005
Posts: 1,601
Likes: 4
From: Texas
How about 3 dyno sheets instead of one ..three different Vortec L31/350's at 440hp plus.
Number 1-
http://www.carcraft.com/techarticles...ock/index.html
Number 2- http://www.popularhotrodding.com/eng...ock/index.html
Number 3-
http://www.speedomotive.com/ps-414-6...er-engine.aspx
Speed-o-Motive is selling a 450hp L31/350 as a crate motor...
Your machine shop can't figure out how to do that once??
2 different magazine staffs have achieved those levels..with nominal preparation... is this rocket science to you??
Some of the Dirt Cars I've wrenched on started with the L31 based GM Circle Track 350 Crate Engine... and have knocked on the door
of 500hp after mild porting.... with L31 Vortec Heads.
The cam I've suggested above and the one's in the articles above-
all streetable... the 230 dur @ .050 Engle is only a 270 duration total
cam with a slightly more aggressive LSA than Lingenfelter 112 LSA cams they sell for EFI cars that don't like loping.... a 2 points tighter cam.
Stock 5.0 87-93 Mustangs came with 266 duration cams from the
factory.. so I'm having a little trouble with your complaint & "expertise".
Lifting the valves to flow 450hp worth of air/fuel mixture CFM is only
scientific if that's what you are trying to achieve... I don't really
understand what direction you are going but it's not what I would
choose...we're probably going to have to agree to disagree because
Im not going to agree with your suggestions.
Number 1-
http://www.carcraft.com/techarticles...ock/index.html
Number 2- http://www.popularhotrodding.com/eng...ock/index.html
Number 3-
http://www.speedomotive.com/ps-414-6...er-engine.aspx
Speed-o-Motive is selling a 450hp L31/350 as a crate motor...
Your machine shop can't figure out how to do that once??
2 different magazine staffs have achieved those levels..with nominal preparation... is this rocket science to you??
Some of the Dirt Cars I've wrenched on started with the L31 based GM Circle Track 350 Crate Engine... and have knocked on the door
of 500hp after mild porting.... with L31 Vortec Heads.
The cam I've suggested above and the one's in the articles above-
all streetable... the 230 dur @ .050 Engle is only a 270 duration total
cam with a slightly more aggressive LSA than Lingenfelter 112 LSA cams they sell for EFI cars that don't like loping.... a 2 points tighter cam.
Stock 5.0 87-93 Mustangs came with 266 duration cams from the
factory.. so I'm having a little trouble with your complaint & "expertise".
Lifting the valves to flow 450hp worth of air/fuel mixture CFM is only
scientific if that's what you are trying to achieve... I don't really
understand what direction you are going but it's not what I would
choose...we're probably going to have to agree to disagree because
Im not going to agree with your suggestions.
Last edited by KyleDallas; Sep 21, 2007 at 04:10 PM.
Le Mans Master
Joined: Apr 2001
Posts: 5,941
Likes: 281
From: Was New Orleans but swam to Baton Rouge LA
Cruise-In IX Veteran
Make sure you have the base mods first (headers, and a good carb). After the base is done go ahead and swap the cam first. Even with stock heads you will pick up considerable power. If you want to the cam, heads, and intake would net you the best results. Just make sure you match your components.