thoughts on this build - 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
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 11-09-2008, 06:47 PM
this hobby is expensive!
 
Join Date: Aug 2008
Location: south haven
Posts: 105
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
thoughts on this build

check out this build for a 383 and let me know what you think. feel free to criticize i can handle it.


eagle rotating assembly forged steel crank h-beam rods
forges aluminum flat top pistons @5cc
6" rods
11:1 compression with 64cc heads
9.7:1 with 76cc heads


dart iron eagle platinums
200cc intake ports
64cc combustion chamber
2.02" int/1.600" exh valves
.620" max lift


comp cams xtreme energy camshaft
hydrualic roller
lift .510"/.520"
duration 282/288
rpm range 2200 to 5800


edelbrock rpm airgap
750 carb edelbrock or holly

    Advertisement

Last edited by boatanchors; 11-09-2008 at 07:00 PM. Reason: hit post by mistake
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 11-09-2008, 07:02 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,570
Wiki Edits: 0

Thanks: 3
Thanked 336 Times in 333 Posts
No camshaft? 11:1 is a lot for a street motor. Better to concentrate on volumetric efficientcy to get the power and then leave yourself some room for the variations on real work driving conditions and fuel quality variations you are going to encounter. The octane requirement of a motor goesw up with age. ( carbon build up, oil contamination in the combustion chamber). If you build a efficient motor, you don;t need to ride the edge of the compression ratio limit to get the performance you're after.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 11-09-2008, 07:07 PM
this hobby is expensive!
 
Join Date: Aug 2008
Location: south haven
Posts: 105
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
so going with the 72 or 76cc combustion chamber heads would probably be better. that makes sence and it probably wouldnt hurt me power wise either
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 11-09-2008, 07:17 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,570
Wiki Edits: 0

Thanks: 3
Thanked 336 Times in 333 Posts
You picked the compression ratio first. You should pick it last.
No mention of the actual fuel you'll be using, car its going in etc etc etc.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 11-09-2008, 07:26 PM
this hobby is expensive!
 
Join Date: Aug 2008
Location: south haven
Posts: 105
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
1962 chevy truck long bed. 3:73 gear 2000-2200 stall in a 400 turbo
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 11-09-2008, 07:40 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 8,708
Wiki Edits: 0

Thanks: 17
Thanked 286 Times in 266 Posts
I disagree with picking it last, the cam should be picked partly on what compression you'll be running. I pick the engine parameters (bore and stroke) then the heads, then the pistons, pick the gasket for quench, see where the compression falls at and then pick the cam. The reason I pick the pistons and see where the compression falls is because there is a lot more of a restriction on piston dish/dome volumes than there is on cam lobe profiles. If I know I want 4vr flat top pistons with a 64cc chamber on a sbc 355 with .40 quench then I can pick my cam to match.

HOWEVER some initial toughts on cam choice need to be made before piston selection so that we know about what we want (trucks get 9.5:1 rather than 10.5:1 for example due to higher loading and the desire for a smaller camshaft to move the torque band down).
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 11-09-2008, 08:11 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,570
Wiki Edits: 0

Thanks: 3
Thanked 336 Times in 333 Posts
Quote:
Originally Posted by ap72
I disagree with picking it last, the cam should be picked partly on what compression you'll be running. I pick the engine parameters (bore and stroke) then the heads, then the pistons, pick the gasket for quench, see where the compression falls at and then pick the cam. The reason I pick the pistons and see where the compression falls is because there is a lot more of a restriction on piston dish/dome volumes than there is on cam lobe profiles. If I know I want 4vr flat top pistons with a 64cc chamber on a sbc 355 with .40 quench then I can pick my cam to match.

HOWEVER some initial toughts on cam choice need to be made before piston selection so that we know about what we want (trucks get 9.5:1 rather than 10.5:1 for example due to higher loading and the desire for a smaller camshaft to move the torque band down).

Pick the cam based on where you want the motors torque curve to occur.
Not to adjust the cylinder pressure.
That does not work. You just end up with a over cammed, inefficient, less powerfull, fuel hungry, peaky, polluting engine that makes less overall power than it could be. Think about it. If you want to make more power, cam the motor so that the induction and exhaust wave tuning is optimized (volumetric efficientcy) to fill and evac the cylinders as best as possible in the usable rpm range. Over cam it and you're allowing potential air/fuel to pass right thru the motor or get pumped right back into the intake manifold.

Trap as much air/fuel in the cylinder and compress it to a point below the point of spark knock and you'll make more power than trying to compress less air/fuel charge by X+1 to get the power. you'll go faster. on less fuel.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 11-09-2008, 11:57 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,599
Wiki Edits: 326

Thanks: 701
Thanked 889 Times in 756 Posts
383
Dart Iron Eagle 200
Performer RPM
750 carb
1 3/4" headers
9.70:1 SCR
CompCams XR270HR 270/276, 218/224, 0.528"/0.535" (1.6 rockers intake and exhaust), 110 LSA, installed retarded 2*

RPM HP TQ
2000 153 403
2500 194 407
3000 248 435
3500 311 467
4000 370 485
4500 419 489
5000 458 482
5500 472 451
6000 461 403

Over 450 ft/lbs 3200-5500

Calculated using the following flow figures for the heads......
.200 129/114
.300 186/145
.400 229/164
.500 261/172
.600 252/174

Tried 7 different cam grinds. More cam will make a little more horsepower, but the bottom end torque goes away. This cam is the best all around choice. Use the 2000-2200 stall converter you mentioned previously. Plan to buy tires often. (This combo makes 360 ft/lbs @ 1500)

Last edited by techinspector1; 11-10-2008 at 12:35 AM.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 11-10-2008, 06:42 AM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 8,708
Wiki Edits: 0

Thanks: 17
Thanked 286 Times in 266 Posts
Quote:
Originally Posted by F-BIRD'88
Pick the cam based on where you want the motors torque curve to occur.
Not to adjust the cylinder pressure.
That does not work. You just end up with a over cammed, inefficient, less powerfull, fuel hungry, peaky, polluting engine that makes less overall power than it could be. Think about it. If you want to make more power, cam the motor so that the induction and exhaust wave tuning is optimized (volumetric efficientcy) to fill and evac the cylinders as best as possible in the usable rpm range. Over cam it and you're allowing potential air/fuel to pass right thru the motor or get pumped right back into the intake manifold.

Trap as much air/fuel in the cylinder and compress it to a point below the point of spark knock and you'll make more power than trying to compress less air/fuel charge by X+1 to get the power. you'll go faster. on less fuel.
I still don't see where you are getting the "overcammed" theory from. It actaully ends up being right on, more efficent, and more powerful. Its how camshafts are designed from the factory. you pick your opening and closing points and let the duration fall where it may. and the "usable RPM range" is not necessarily as low as I think you always assume it to be. A lot of the guys on here build these projects as toys with 4.10 or steeper gearing, 2500 stall convertors, and TH350 trannys. Which really kicks the usable range up quite a bit.

Your method is probably easier for Joe "First time builder" to understand (which a lot of people on here need), but its not the full picture.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 11-10-2008, 07:02 AM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,570
Wiki Edits: 0

Thanks: 3
Thanked 336 Times in 333 Posts
The example above (intended for a truck. Hello, a truck) is a good example.
Make it 10.7:1 as you promote and it will knock at WOT with full timing. Add valve timing duration in an attempt to lower the tendancy to knock (over cam) and the low end torque goes away (right where you drive a truck most of the time), requireing a high stall converter (not in the builders plans) and a potentually higher rear gear ratio. Now you have a "racey truck" that not going to be fast ( its too friggin heavy anyways) and eats gas.

Over camming a motor does not stop or even tame the tendancy to knock on pump gas. It just makes you a junk motor build that is a lot less than it could be in all respects. and won't last long. It does not work.
You're throwing your money out the window.
Thats called "junk engineering" It's a bad, bad idea no matter what spin you try and put on it.
There are other much better proven ways to allow higher compression ratio with pump gas without the unnessessary compromise, that actually work.

There is a big difference between a well designed and executed high performance street motor for a truck and a "racey truck"
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 11-10-2008, 07:15 AM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 8,708
Wiki Edits: 0

Thanks: 17
Thanked 286 Times in 266 Posts
Quote:
Originally Posted by F-BIRD'88
The example above (intended for a truck. Hello, a truck) is a good example.
Make it 10.7:1 as you promote and it will knock at WOT with full timing. Add valve timing duration in an attempt to lower the tendancy to knock (over cam) and the low end torque goes away (right where you drive a truck most of the time), requireing a high stall converter (not in the builders plans) and a potentually higher rear gear ratio. Now you have a "racey truck" that not going to be fast ( its too friggin heavy anyways) and eats gas.

Over camming a motor does not stop or even tame the tendancy to knock on pump gas. It just makes you a junk motor build that is a lot less than it could be in all respects. and won't last long. It does not work.
You're throwing your money out the window.
Thats called "junk engineering" It's a bad, bad idea no matter what spin you try and put on it.
There are other much better proven ways to allow higher compression ratio with pump gas without the unnessessary compromise, that actually work.

There is a big difference between a well designed and executed high performance street motor for a truck and a "racey truck"
Its far from "junk engineering" its a way to run into the low 11's on mostly stock parts, NA, on pump gas, and still be streetable. And if you run a higher gear, higher stall, and a more powerful engine it will be quicker- there's no arguing that. I wouldn't put a 11:1 engine in a Chevy 2500 with 3.42 gearing, a OD, and 30" tires. But I also wouldn't hesitate to put one in a stripped down S10 with a 700R4, 28" tires and 4.10 gears. A LOT of people build "race trucks" out of those...

And a 250 cam with 11:1 compression is plenty streetable once you put a 2500 stall on it ang match it to some decent gears. It won't drive like a factory fresh cadillac, but it'l still be easy to handle off a stop light.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 11-10-2008, 07:22 AM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,570
Wiki Edits: 0

Thanks: 3
Thanked 336 Times in 333 Posts
Quote:
Originally Posted by ap72
Its far from "junk engineering" its a way to run into the low 11's on mostly stock parts, NA, on pump gas, and still be streetable. And if you run a higher gear, higher stall, and a more powerful engine it will be quicker- there's no arguing that. I wouldn't put a 11:1 engine in a Chevy 2500 with 3.42 gearing, a OD, and 30" tires. But I also wouldn't hesitate to put one in a stripped down S10 with a 700R4, 28" tires and 4.10 gears. A LOT of people build "race trucks" out of those...

And a 250 cam with 11:1 compression is plenty streetable once you put a 2500 stall on it ang match it to some decent gears. It won't drive like a factory fresh cadillac, but it'l still be easy to handle off a stop light.

who are you trying to kid?
A cam with 250 @.050" won;t idle right in gear with just a 2500 stall.
It will be a real mutt too. It won;t run 11's or even 12's. with a 2500 stall.
and the motor will knock at WOT unless you kill the spark timing.
A motor with a 250 cam needs a 3500 stall minimum.
You obviously have not built to many of these.
Junk science junk engineering. slow truck with a rough idle that knocks unless you run some race gas, is all you end up with.

A 4800# truck will require a 625 to 650hp motor to have any chance of running a 11sec 1/4 mile. Give your head a shake.

Last edited by F-BIRD'88; 11-10-2008 at 07:29 AM.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 11-10-2008, 07:48 AM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 8,708
Wiki Edits: 0

Thanks: 17
Thanked 286 Times in 266 Posts
Quote:
Originally Posted by F-BIRD'88
who are you trying to kid?
A cam with 250 @.050" won;t idle right in gear with just a 2500 stall.
It will be a real mutt too. It won;t run 11's or even 12's. with a 2500 stall.
and the motor will knock at WOT unless you kill the spark timing.
A motor with a 250 cam needs a 3500 stall minimum.
You obviously have not built to many of these.
Junk science junk engineering. slow truck with a rough idle that knocks unless you run some race gas, is all you end up with.

A 4800# truck will require a 625 to 650hp motor to have any chance of running a 11sec 1/4 mile. Give your head a shake.
S10's when stripped down come in around 3000 pounds. I know that because I built a few of them. And they are light. And that idle is more dependant on seat timing than @ .050" I have a cam I'm putting in an engine I'm currently building that is adv 279/282, but 248/251 @.050". and it will idle in gear with a 2500 stall. its adv power range is 2700-6800 which puts it right at boderline streetable.
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

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:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

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
Here's where I'm at with my 383 build Malibu73 Engine 17 12-06-2009 08:56 PM
this is a saver.... GM build codes TooMany2count General Rodding Tech 24 11-23-2009 09:36 AM
build a moter or buy a car first? Tryin2MakeIt Engine 19 12-13-2006 09:43 PM
350 build up opinions? Artemis Entreri Engine 17 08-09-2006 01:48 PM
Build your own frame? Any basic thoughts? Madd Syntst Suspension - Brakes - Steering 9 11-28-2002 09:00 PM


All times are GMT -6. The time now is 05:13 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.