First off thanks for directing me to this page. Ok I have a 99 model L31 block that will be bored 30 over to clean up.I already have the heads 906 vortec reworked completly stock but like brand new.I have a new 750 Eldebrock carb. The intake is GM #12486570 alum high rise dual plane.I have a standard 350 crank in a 92 LT motor I could use, the L31 spun a rod bearing. I am planning on putting this motor in a 90 camaro,with th400 trans, 342 posi rear,it most likely wont have ac but power brakes and steering. But if I can put ac in without using to much vac I will. I would like at least 400hp to wheels.Can you suggest cam,rockers,springs,pistons, and anything I left out. I see you know about getting most for your buck and keeping min. expense down.Can I make any of the parts I have work? And should I go 355 or 388? Oh yea Grumpy this will be a street car, strip maybe once in a while. And really would like to keep rpm to 6500 max but maybe I am dreaming, but I would like to smoke that T/A and hes running 11.70. Thanks for your advice. Dusty
355 or 388
- Thread starter Dustytrix
- Start date
http://detroit.craigslist.org/okl/pts/1386037300.html
for those that don,t know heres a picture of that dual plane vortec intake (LINK ABOVE)
ok back to the problem,IM not directing this answer just at your engine but more as a teaching aid for ANYONE reading this, hopefully getting them to use the links and calculators on the site, and thinking about what their choices in components do for the combo they build...keep in mind its fairly RARE for a complete engine to exceed 90% of the parts combos potential based on several factors like flow rates and piston speeds so always build something with a bit more potential power than you need, as a general rule its consistently more difficult to exceed 1.1 horse power per cubic inch of displacement in an engine designed for street use, as you push the upper power potential limits.
400 REAR WHEEL HORSEPOWER will require about 480-500 flywheel horsepower , so lets look at a few factors
, in most cases a well laid out STREET engine combo will produce roughly similar torque and hp numbers, IE it will produce its peak hp and torque in the 4700-5800rpm band, so that you don,t need to spin the engine to 6500rpm 7500rpm to get peak power, which is a really good thing with a dual plane intake and vortec heads, as both are designed for max hp at well below 5000 rpm, UNDER IDEAL CONDITIONS, YOU'LL REACH SOME OF THESE NUMBERS, but the intake must flow as well or better than the heads and it REQUIRES a TUNED low restriction exhaust with headers that scavenge the cylinders efficiently, the correct cam timing, and not getting into detonation, etc, ans almost NO ONE, manages to build a combo that reaches 100% of the combined potential of all the components, and youll need to match the cars drive train, gearing, and stall speed to the engines power band.keep in mind the 383-388 will ALWAYS have an advantage because of its larger displacement, that advantage is generally in the 35-40 ft lbs range over a similar 350 displacement, over most of the mid rpm range, but keep in mind piston speeds and valve train control issues really limit the 3.75" stroke 383 style with hydraulic lifter combos to about 6300rpm
the formula for horse power is engine torque x rpm divided bye 5252
example
if you have 500 ft lbs of torque at 3900rpm....
500 ft lbs x 3900rpm /5252=371 hp
read these,THREADS AND SUB LIKED INFO and think thru your choices
viewtopic.php?f=52&t=796
viewtopic.php?f=52&t=333
viewtopic.php?f=53&t=2733&p=7098#p7098
viewtopic.php?f=38&t=1099&p=2152&hilit=volumetric#p2152
viewtopic.php?f=50&t=1652&p=3987&hilit=volumetric#p3987
viewtopic.php?f=56&t=185
http://www.blueprintengines.com/popular ... s&pc_id=67
one major factor will be limited air flow rates, and volumetric efficiency as rpms increase
ok what we find is that a stock small port vortec heads has a port cross section of 1.66 sq inches
with standard small port vortec heads peak flow and torque ,will vary some, with the compression ratio and cam duration selected, but with a cam designed for street rpm ranges will be reached at just over 3100-3600rpm on a 383, and at about 3400-4200rpm with a 350, and that torque level at least in an ideal combo will roughly be maintained or slightly increased until port stall becomes a restriction to volumetric efficiency
http://www.rbracing-rsr.com/runnertorquecalc.html
you MIGHT be able to make 1.25 ft lbs of tq at peak torque at the max port flow per cubic inch of displacement limited to pump gas octane fuel
so for a 350 thats 437 ft lbs at 3400rpm=283hp
so for a 383 thats 478 ft lbs at 3100rpm=283hp
but thats not where the port flow stalls
http://www.slowgt.com/Calc2.htm#MinCross
http://www.wallaceracing.com/max-rpm2.php
on a vortec head on a 350 thats at 5600rpm=465hp
on a vortec head on a 383 thats at 5200rpm=473hp
so your going to be just a bit restricted even in an ideal combo from your goal using the stock small port vortec heads in stock condition under those conditions
Potential HP based on Airflow (Hot Rod, Jun '99, p74):
Airflow at 28" of water x 0.257 x number of cylinders = potential HP
or required airflow based on HP:
HP / 0.257 / cylinders = required airflow
vortec heads flow about 230cfm peak=470hp peak, which matches the other calculation
btw the stock small port vortec heads don,t benefit significantly from effective cam lifts over about 0.550 or duration of over about 234 on the intake timing, simply because as the rpms increase the time available to allow the cylinders to fill decreases and port flow is limited
and in stock form the springs limit you to about a .470 lift, by about 5200rpm on a 383 its beginning to be almost hopeless
READ THESE THREE, ENGINE BUILD UPs and notice the common factors, in required head flow, etc,
http://airflowresearch.com/articles/article085/A-P1.htm
http://airflowresearch.com/articles/article031/A-P1.htm
viewtopic.php?f=69&t=1040&p=1943&hilit=206cc#p1943
play with the calculators, think thru the info,
and you'll find
the LARGE PORT VORTEC HEADS MEET YOUR GOAL EASILY IF MATCHED TO A 10.5:1 CPR 383 sbc combo and a CAM like this, add 1.6:1 roller rockers, provided the intake and exhaust also don,t provide a restriction, and you use a 3000rpm stall converter on that th400 with that 3.42 rear gear ratio, and realize the power curve with the larger heads will be about 3000rpm-6200rpm with that cam, but you'll get to the 400 rear wheel hp goal if everything's done correctly
Large-Port Vortec Cylinder Head Flow
INTAKE
EXHAUST
Lift Volume Lift Volume
0.200 128.6 0.200 100.8
0.300 188.4 0.300 138.6
0.400 234.8 0.400 154.4
0.500 257.2 0.500 152.5
0.600 263.2 0.600 163.8
0.700 269.1 0.700 167.0
http://www.crower.com/misc/cam_spec/cam ... 1&x=51&y=9
http://www.rpmmachine.com/383-chevy-for ... r-sb.shtml
http://www.adperformance.com/index.php? ... th=277_278
QUESTIONS?< DISCUSSION?
for those that don,t know heres a picture of that dual plane vortec intake (LINK ABOVE)
ok back to the problem,IM not directing this answer just at your engine but more as a teaching aid for ANYONE reading this, hopefully getting them to use the links and calculators on the site, and thinking about what their choices in components do for the combo they build...keep in mind its fairly RARE for a complete engine to exceed 90% of the parts combos potential based on several factors like flow rates and piston speeds so always build something with a bit more potential power than you need, as a general rule its consistently more difficult to exceed 1.1 horse power per cubic inch of displacement in an engine designed for street use, as you push the upper power potential limits.
, in most cases a well laid out STREET engine combo will produce roughly similar torque and hp numbers, IE it will produce its peak hp and torque in the 4700-5800rpm band, so that you don,t need to spin the engine to 6500rpm 7500rpm to get peak power, which is a really good thing with a dual plane intake and vortec heads, as both are designed for max hp at well below 5000 rpm, UNDER IDEAL CONDITIONS, YOU'LL REACH SOME OF THESE NUMBERS, but the intake must flow as well or better than the heads and it REQUIRES a TUNED low restriction exhaust with headers that scavenge the cylinders efficiently, the correct cam timing, and not getting into detonation, etc, ans almost NO ONE, manages to build a combo that reaches 100% of the combined potential of all the components, and youll need to match the cars drive train, gearing, and stall speed to the engines power band.keep in mind the 383-388 will ALWAYS have an advantage because of its larger displacement, that advantage is generally in the 35-40 ft lbs range over a similar 350 displacement, over most of the mid rpm range, but keep in mind piston speeds and valve train control issues really limit the 3.75" stroke 383 style with hydraulic lifter combos to about 6300rpm
the formula for horse power is engine torque x rpm divided bye 5252
example
if you have 500 ft lbs of torque at 3900rpm....
500 ft lbs x 3900rpm /5252=371 hp
read these,THREADS AND SUB LIKED INFO and think thru your choices
viewtopic.php?f=52&t=796
viewtopic.php?f=52&t=333
viewtopic.php?f=53&t=2733&p=7098#p7098
viewtopic.php?f=38&t=1099&p=2152&hilit=volumetric#p2152
viewtopic.php?f=50&t=1652&p=3987&hilit=volumetric#p3987
viewtopic.php?f=56&t=185
http://www.blueprintengines.com/popular ... s&pc_id=67
one major factor will be limited air flow rates, and volumetric efficiency as rpms increase
ok what we find is that a stock small port vortec heads has a port cross section of 1.66 sq inches
with standard small port vortec heads peak flow and torque ,will vary some, with the compression ratio and cam duration selected, but with a cam designed for street rpm ranges will be reached at just over 3100-3600rpm on a 383, and at about 3400-4200rpm with a 350, and that torque level at least in an ideal combo will roughly be maintained or slightly increased until port stall becomes a restriction to volumetric efficiency
http://www.rbracing-rsr.com/runnertorquecalc.html
you MIGHT be able to make 1.25 ft lbs of tq at peak torque at the max port flow per cubic inch of displacement limited to pump gas octane fuel
so for a 350 thats 437 ft lbs at 3400rpm=283hp
so for a 383 thats 478 ft lbs at 3100rpm=283hp
but thats not where the port flow stalls
http://www.slowgt.com/Calc2.htm#MinCross
http://www.wallaceracing.com/max-rpm2.php
on a vortec head on a 350 thats at 5600rpm=465hp
on a vortec head on a 383 thats at 5200rpm=473hp
so your going to be just a bit restricted even in an ideal combo from your goal using the stock small port vortec heads in stock condition under those conditions
Potential HP based on Airflow (Hot Rod, Jun '99, p74):
Airflow at 28" of water x 0.257 x number of cylinders = potential HP
or required airflow based on HP:
HP / 0.257 / cylinders = required airflow
vortec heads flow about 230cfm peak=470hp peak, which matches the other calculation
btw the stock small port vortec heads don,t benefit significantly from effective cam lifts over about 0.550 or duration of over about 234 on the intake timing, simply because as the rpms increase the time available to allow the cylinders to fill decreases and port flow is limited
and in stock form the springs limit you to about a .470 lift, by about 5200rpm on a 383 its beginning to be almost hopeless
READ THESE THREE, ENGINE BUILD UPs and notice the common factors, in required head flow, etc,
http://airflowresearch.com/articles/article085/A-P1.htm
http://airflowresearch.com/articles/article031/A-P1.htm
viewtopic.php?f=69&t=1040&p=1943&hilit=206cc#p1943
play with the calculators, think thru the info,
and you'll find
the LARGE PORT VORTEC HEADS MEET YOUR GOAL EASILY IF MATCHED TO A 10.5:1 CPR 383 sbc combo and a CAM like this, add 1.6:1 roller rockers, provided the intake and exhaust also don,t provide a restriction, and you use a 3000rpm stall converter on that th400 with that 3.42 rear gear ratio, and realize the power curve with the larger heads will be about 3000rpm-6200rpm with that cam, but you'll get to the 400 rear wheel hp goal if everything's done correctly
Large-Port Vortec Cylinder Head Flow
INTAKE
EXHAUST
Lift Volume Lift Volume
0.200 128.6 0.200 100.8
0.300 188.4 0.300 138.6
0.400 234.8 0.400 154.4
0.500 257.2 0.500 152.5
0.600 263.2 0.600 163.8
0.700 269.1 0.700 167.0
http://www.crower.com/misc/cam_spec/cam ... 1&x=51&y=9
http://www.rpmmachine.com/383-chevy-for ... r-sb.shtml
http://www.adperformance.com/index.php? ... th=277_278
QUESTIONS?< DISCUSSION?
Last edited by a moderator:
Thanks for replying, lots of reading to do, but I didnt see if this intake would match good with the 906 heads,also I am going to get the bosses cut down for roller rockers, and better springs. Looks like I wont be able to reach 400hp at wheels but I would like to get as close as I can with the parts I have if I can make them match. I will keep researching. Dusty 
the intake is not a bad choice for mid rpm torque on a street car engine but its certainly restrictive if you want to exceed 450 flywheel hp compared to some other choices, but keep in mind displacement, cam timing and compression ratio play a big part in determining the engines potential
example
http://www.summitracing.com/parts/EDL-2913/
example
http://www.summitracing.com/parts/EDL-2913/
just an option I should post so you know its available
http://www.dougherbert.com/383chevysbst ... 14_615_748
383 Chevy SB "Stroker" High Output
485 hp, Hydraulic roller cam
DHP383HO $5,699.99
383 Chevy SB "Stroker" High Output
Click to enlarge
This Doug Herbert stroked Chevrolet Small-Block Engine produces over 485 horsepower and is assembled using the highest quality components at a reasonable price.
Please call 877-497-2787 if you have any questions or would like to phone in your order.
This engine includes:
# Fully machined GM block
# Dart PRO 1 race ready heads with 215cc intake runner and 2.05/1.60 race valves
# Premium Forged Pistons
# Scat I beam rods 6 inch rods with floating pins
# Herbert Hydraulic Roller Cam - .567/.585 lift .242/.246 duration on 112LC
# Herbert Hydraulic Roller Lifters
# Aluminum roller rocker arms
# Comp cams push rods
# Cloyes double roller chain
# Melling high volume oil pump
# Clevite 77 bearings
# Fel Pro gasket set
# Pro tech 7 quart pan & pick up
# Professional Products Crosswind Intake, satin finish
# Professional Products harmonic balancer
# Moly rings
# ARP head bolts
# ARP oil pump stud
# Pioneer brass freeze plugs
# Internal balanced
# Add a 4-Bolt Main for $250
# Add 230cc Runner Heads for $100.00
# Add Solid Roller & Stud Girdles for no extra charge.
more options
http://ohiocrank.com/enginespage1.html
http://www.dougherbert.com/383chevysbst ... 14_615_748
383 Chevy SB "Stroker" High Output
485 hp, Hydraulic roller cam
DHP383HO $5,699.99
383 Chevy SB "Stroker" High Output
Click to enlarge
This Doug Herbert stroked Chevrolet Small-Block Engine produces over 485 horsepower and is assembled using the highest quality components at a reasonable price.
Please call 877-497-2787 if you have any questions or would like to phone in your order.
This engine includes:
# Fully machined GM block
# Dart PRO 1 race ready heads with 215cc intake runner and 2.05/1.60 race valves
# Premium Forged Pistons
# Scat I beam rods 6 inch rods with floating pins
# Herbert Hydraulic Roller Cam - .567/.585 lift .242/.246 duration on 112LC
# Herbert Hydraulic Roller Lifters
# Aluminum roller rocker arms
# Comp cams push rods
# Cloyes double roller chain
# Melling high volume oil pump
# Clevite 77 bearings
# Fel Pro gasket set
# Pro tech 7 quart pan & pick up
# Professional Products Crosswind Intake, satin finish
# Professional Products harmonic balancer
# Moly rings
# ARP head bolts
# ARP oil pump stud
# Pioneer brass freeze plugs
# Internal balanced
# Add a 4-Bolt Main for $250
# Add 230cc Runner Heads for $100.00
# Add Solid Roller & Stud Girdles for no extra charge.
more options
http://ohiocrank.com/enginespage1.html
I think I will make the most of what I have, that motor is nice but way out of my budget. Maybe after kids get out of college I could buy a motor like that. I saw the 350 budget build in June issue of hot rod, I hope to put together somthing like that except I will use roller lifters, cam, rockers and gain 33 inches on them with the scat crank. Thanks for your help, I will keep studying your post.
viewtopic.php?f=69&t=519
you also might want to read thru the sub linked info on this thread as theres some very useful examples
as you do more engines youll get experience and the process becomes easier, almost second nature as they say.
an AIR DIE GRINDER and a carbide burr and cut off wheels make the process fast and easier than electric drills
viewtopic.php?f=27&t=1831
viewtopic.php?f=50&t=1266
keep in mind cap screw rods (bolts screw into the upper rod from cap)
generally require less block clearance work, have much more cam-to-rod clearance and are usually stronger than O.E.M. rods
when you go to clearance a block and select components read the fine print on what your buying and remember to clearance the block and rods to clear the cam lobes, a clearance of,0.050" is OK, Ive always suggested 0.060" but thats not enough difference in clearance in that application to worry about.
EXAMPLE SCAT,IF your looking to save money theres a good deal of variation in kit components,aftermarket connecting rods with ARP 3/8" bolts are significantly stronger than stock rod bolts, and connecting rods so they are a big improvement, but in the future Id suggest looking at similar 7/16" cap screw rod kits with internally balanced cranks for most builds as the cost is usually only minimally higher.
forged cranks are nice, to brag about, but certainly more expensive and not required for a street/strip 383 that seldom sees 6400rpm,or similar applications
as a general rule you'll find 7/16" rods add about 20% more strength for a minimal cost upgrade.
3/8" rods(Fastener Yield Strength (psi) 160,000 psi)
http://www.summitracing.com/parts/ESP-5700BPLW/
7/16" rods
Fastener Yield Strength (psi)200,000 psi
http://www.summitracing.com/parts/SCA-26000716/
http://www.summitracing.com/parts/SCA-25700716/
you also might want to read thru the sub linked info on this thread as theres some very useful examples
as you do more engines youll get experience and the process becomes easier, almost second nature as they say.
an AIR DIE GRINDER and a carbide burr and cut off wheels make the process fast and easier than electric drills
viewtopic.php?f=27&t=1831
viewtopic.php?f=50&t=1266
keep in mind cap screw rods (bolts screw into the upper rod from cap)
generally require less block clearance work, have much more cam-to-rod clearance and are usually stronger than O.E.M. rods
when you go to clearance a block and select components read the fine print on what your buying and remember to clearance the block and rods to clear the cam lobes, a clearance of,0.050" is OK, Ive always suggested 0.060" but thats not enough difference in clearance in that application to worry about.
EXAMPLE SCAT,IF your looking to save money theres a good deal of variation in kit components,aftermarket connecting rods with ARP 3/8" bolts are significantly stronger than stock rod bolts, and connecting rods so they are a big improvement, but in the future Id suggest looking at similar 7/16" cap screw rod kits with internally balanced cranks for most builds as the cost is usually only minimally higher.
forged cranks are nice, to brag about, but certainly more expensive and not required for a street/strip 383 that seldom sees 6400rpm,or similar applications
as a general rule you'll find 7/16" rods add about 20% more strength for a minimal cost upgrade.
3/8" rods(Fastener Yield Strength (psi) 160,000 psi)
http://www.summitracing.com/parts/ESP-5700BPLW/
7/16" rods
Fastener Yield Strength (psi)200,000 psi
http://www.summitracing.com/parts/SCA-26000716/
http://www.summitracing.com/parts/SCA-25700716/
OK I haven,t read all of the topics yet.But from what I have read it keeps pointing me to the victor jr. intake and I am leaning to the gm hot roller cam. I can,t remember the topic but it was showing the hot cam with different intakes, even one close to mine and just by going with victor jr they got something like 15 or more hp. This site is the best info place I have found. Thanks Dusty
http://www.summitracing.com/parts/HLY-300-110/
every time Ive tested the weiand intake above, on a hot 383 sbc against the edelbrock vic jr the weiand produced better upper mid rpm ( 5000rpm and up) and peak hp
the weiand intake is NOT designed for vortec heads but matched to a decent set of heads from DART,BRODIX,TRICKFLOW,AFR, in the 250 plus CFM flow at .500 lift flow range, and 195cc-230cc port size and a cam in the 245 degrees plus duration range with the matched drive train and compression ETC. its proven superior in my experiences, the edelbrocks designed more with the mid rpm range (3700rpm-5000rpm) and hood clearance as factors
the weiand intake I linked to has got less hood clearance but in my opinion a much better runner design
read thru these
viewtopic.php?f=53&t=2733
viewtopic.php?f=52&t=727
viewtopic.php?f=52&t=796
viewtopic.php?f=52&t=1070
viewtopic.php?f=54&t=615
every time Ive tested the weiand intake above, on a hot 383 sbc against the edelbrock vic jr the weiand produced better upper mid rpm ( 5000rpm and up) and peak hp
the weiand intake is NOT designed for vortec heads but matched to a decent set of heads from DART,BRODIX,TRICKFLOW,AFR, in the 250 plus CFM flow at .500 lift flow range, and 195cc-230cc port size and a cam in the 245 degrees plus duration range with the matched drive train and compression ETC. its proven superior in my experiences, the edelbrocks designed more with the mid rpm range (3700rpm-5000rpm) and hood clearance as factors
the weiand intake I linked to has got less hood clearance but in my opinion a much better runner design
read thru these
viewtopic.php?f=53&t=2733
viewtopic.php?f=52&t=727
viewtopic.php?f=52&t=796
viewtopic.php?f=52&t=1070
viewtopic.php?f=54&t=615