383 Question
Le Mans Master
Joined: Feb 1999
Posts: 5,877
Likes: 1
From: Park Ridge IL
Re: 383 Question (M2001)
The advantages of using a 6.0" rod over a 5.7" rod is the better rod/stroke ratio. The 6.0" rod yields a 1.6 rod/stroke ratio, while the 5.7" rod yields a 1.52 rod/stroke ratio. Neither rod/stroke ratio is optimum, but the higher ratio is preferred. The higher the rod/stroke ratio, the less side thrust loading that is uncurred. Side thrust loading increases internal friction costing power, and increasing cylinder wall/piston/ring wear. It also diminishes the engines ability to rev quickly.
There are arguments that a longer rod has a small effect on overall power production due to the piston dwell time, but in most cases the difference is very small.
Another benefit of running a longer rod is that the piston pin is moved higher up in the piston. The allows you to run a shorted, lighter piston, and the higher piston pin location reduces piston rock.
There are arguments that a longer rod has a small effect on overall power production due to the piston dwell time, but in most cases the difference is very small.
Another benefit of running a longer rod is that the piston pin is moved higher up in the piston. The allows you to run a shorted, lighter piston, and the higher piston pin location reduces piston rock.
Drifting
Joined: Dec 1999
Posts: 1,462
Likes: 1
From: Reno nevada
Re: 383 Question (M2001)
I can't verify why. So it could be the rod type. not just the angle/rod ratio/pin height. But I've seen a few stroker motors being put together. It seemed to me that the short rod motors even required grinding on the cylinder hole bases near the center line. The long rod versions were only ground on the passenger side pan rail and the first hole or two on the drivers front.
I've also seen magazine testing data that seems to indicate that longer rods have better anti-detonation properties. I have never heard proof one way or the other on any power gains. What the other poster said about thrust and piston rock are correct.
I've also seen magazine testing data that seems to indicate that longer rods have better anti-detonation properties. I have never heard proof one way or the other on any power gains. What the other poster said about thrust and piston rock are correct.
Thread Starter
Burning Brakes
Joined: Apr 2000
Posts: 900
Likes: 0
From: New Jersey
Re: 383 Question (Lt1er)
Another question, with the longer rods (6.0 inch), will I have to notch the block? Or, is notching block dependant? The reason why I'm asking these questions is because at one time, I was going to sell my car for a new ride. Now I'm thinking that I should hold onto my car a little while longer however, I'm sizing up the idea of building a 383. I know that GM sells a crate 383 motor but it has 5.7 inch rods. It does however carry a 12 month/12K mile warrantee. I also saw a crate 383 with fast burn heads for about $5550 from GM. I know that Lunati makes a nice stroker kit and Summit Racing sells it for about $1700. The kit has a steel crank and forged flat top pistons and pretty decent rods too. The kit is good for up to 450 hp and it sounds like a nice complete package. I'm just trying to figure what path to take.
Thanks again for any input.
Thanks again for any input.
Melting Slicks
Joined: Jun 2000
Posts: 3,215
Likes: 6
From: Tampa Florida
Re: 383 Question (M2001)
The thing I don't like about the 5.85 or 6.0 inch rods is they require a support for the oil scrapper rings due to the piston pin intersecting the land.
This seems to be proven in short term, but I wonder about long term-like 20,000 miles does you oil consumption go sky high?
I like to do the stuff myself, so simplicity is preferred-I would go with the short rod everytime.
Obviously my opinion...
Good Luck!
This seems to be proven in short term, but I wonder about long term-like 20,000 miles does you oil consumption go sky high?
I like to do the stuff myself, so simplicity is preferred-I would go with the short rod everytime.
Obviously my opinion...
Good Luck!
Le Mans Master
Joined: Feb 1999
Posts: 5,877
Likes: 1
From: Park Ridge IL
Re: 383 Question (No Go)
I was a little concerned about that too - the oil ring being over the piston pin, but I found out that there are several production engines that are designed this way. I felt that if a manufacturer feels confident enough to warranty a car for 50-60K miles with this design, it should be good enough for me. I'm runnign 6.125" rods, and I haven't detected any problems with the pin in the oil ring. JE said it's not a problem as well, and besides the OEM applications, there are plenty of guys out there with pistons like this, and Ive never heard any complaints from them either.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: 383 Question (No Go)
I use 6 inch rods 383. I thought it to be funny that a guy with his car covered with race stickers was concerned about oil consumption and the motor lasting 20K miles! :lol:
stroker motors just seem to run better than just the small % of additional cubic inches. I would do it all over again - but with 3.875 stroke.
Oil consumption is from the amount of horse pressure and rpm. If you really look at ring and piston design. None of the rings should ever touch the bottom of the piston ring groove. Rings are supported vertically by the piston and by design, expand against the cylinder wall.
stroker motors just seem to run better than just the small % of additional cubic inches. I would do it all over again - but with 3.875 stroke.
Oil consumption is from the amount of horse pressure and rpm. If you really look at ring and piston design. None of the rings should ever touch the bottom of the piston ring groove. Rings are supported vertically by the piston and by design, expand against the cylinder wall.
Thread Starter
Burning Brakes
Joined: Apr 2000
Posts: 900
Likes: 0
From: New Jersey
Re: 383 Question (No Go)
First off, I want to express my gratitude to all those who responded. Your information has enlighten me to the different aspects of building a 383.
I purchased an Accel DFI unit built for a 383. I also saw this 383 on this website, have a look: http://www.goautocenter.com/383_small_blk.htm If I buy this engine, I think I would prefer to use GM's hot cam instead of the cam that comes with this package. I figure if I add a miniram, that should put me in the 400+ hp catagory with decent torque. Add a nice 2800-3000 stall speed converter with lock up, and the trans would be set. I also have a set of nice stainless steel, ceramic coated Callaway shorty headers built for a D port L98 head. I think my headers will hook up to the GM fast burn aluminum heads without much fuss.
I'm wondering, how does this set up sound so far? I welcome any respones to this set up.
Thanks again
I purchased an Accel DFI unit built for a 383. I also saw this 383 on this website, have a look: http://www.goautocenter.com/383_small_blk.htm If I buy this engine, I think I would prefer to use GM's hot cam instead of the cam that comes with this package. I figure if I add a miniram, that should put me in the 400+ hp catagory with decent torque. Add a nice 2800-3000 stall speed converter with lock up, and the trans would be set. I also have a set of nice stainless steel, ceramic coated Callaway shorty headers built for a D port L98 head. I think my headers will hook up to the GM fast burn aluminum heads without much fuss.
I'm wondering, how does this set up sound so far? I welcome any respones to this set up.
Thanks again
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Melting Slicks
Joined: Jun 2000
Posts: 3,215
Likes: 6
From: Tampa Florida
Re: 383 Question (M2001)
You got me there gkull! Honestly the stickers came off after the event and I use it daily (14,000 miles this year!)
I was unaware of OEM using this type of piston. Does make me feel better, but still seems like bit more risk...guess that is from a perspective of self engine builder-"if I CAN screw it up I will!" during engine assembly
M2001: That looks like a cool engine. I believe those are the Vortec cylinder heads they use in the 325 horse motor and they will require new springs (LT4 type work for 40 bucks) and the requisite maching of the spring pockets. The latest Chevy High Performance has an excellent article on build up and dyno test of a 355 with Vortec heads/HOT cam. They pumped out 412 horse and 423 torque with a Performer intake. Adding extra 30 cubes and MR or even new Scoggins Dickens TPI base-would make an interesting combo. Total engine cost for this was under $2500!
I was unaware of OEM using this type of piston. Does make me feel better, but still seems like bit more risk...guess that is from a perspective of self engine builder-"if I CAN screw it up I will!" during engine assembly
M2001: That looks like a cool engine. I believe those are the Vortec cylinder heads they use in the 325 horse motor and they will require new springs (LT4 type work for 40 bucks) and the requisite maching of the spring pockets. The latest Chevy High Performance has an excellent article on build up and dyno test of a 355 with Vortec heads/HOT cam. They pumped out 412 horse and 423 torque with a Performer intake. Adding extra 30 cubes and MR or even new Scoggins Dickens TPI base-would make an interesting combo. Total engine cost for this was under $2500!