The Rod Discussion
11-08-2003, 02:55 PM
#1
Rennlist Member
Thread Starter
The Rod Discussion
My engine is apart. It has been for a while. I have almost everything planned out for the reassembly of my new and improved beast-to-be.
A few issues that I wanted to sound off at this board about, but I will not sully and confuse this thread with more then one.
Connecting Rods:
Here is a place that sells very nice rods that would probably survive 7000rpm easily. Many times there are power ratings used for connecting rods, especially in places like summit racing Such as you see in that link. 7000rpm, 12.5 compression, and 600hp. Well, obviously that means they are strong.
The issue is that the RPM that a rod is operated at really is the determining issue with whether or not it will survive. Engines chuck rods, usually, because of a reving situation, not because of the power pushing on them. Its the pulling that breaks them.
Ah, but what about this? That spagetti on the left is not fron stretching. That thing was pushed into that shape. (BTW, if you can see the darker rod, that is what the 944 turbo rods are like, as well as the 87 and 88 rods on the 928. FWIW, a 1984 944's rods are FORGED, as well as the 86 turbos.
Sure, it woul dbe nice to find 8 944 turbo rods for my engine and be done with it. Unfortunatly, it looks as though everybody else is looking for them to, and the market is charging what it will bear.
The solution? I have two, and that is what I wanted to speak with you all about. I am already spending probably 6k on the engine before I put it back in, with the sleeving, the crank work, and pistons, and maybe head work (some smoothing/cam change/springs, etc).
So while this may sound "cheap", this is what I have found. If I had the extra cash, I would just drive down to Chula Vista, CA (south of San Diego), and buy a nice set of these for 1800 dollars. Cash and carry, no special sizes for the crank diamter, and the JE pistons being made aren't an issue either way.
.....or I could possibly save (several hundred?) by doing something crazy and getting a set of these. for 500 bucks, or similar.
Questions:
Can the big end of a forged rod be resized? The BE bore of a 944/928 rod is 2.165 inches. Many Chevy rods are around 2.10. Is there a readily available bearing that would be oversized enough to being the ID with bearing back to the required measurement of the crank journal? Or as I said, can the big end of the rod be resized to 2.165, and then I could use the stock bearings! Ah, but the rub is the cost. Resizing may bring me back up to the price, or close to the price, of the $1800 pauters. And what of strength? Are these mass produced chevy rods THAT strong? They sure as hell are cheap!
A few issues that I wanted to sound off at this board about, but I will not sully and confuse this thread with more then one.
Connecting Rods:
Here is a place that sells very nice rods that would probably survive 7000rpm easily. Many times there are power ratings used for connecting rods, especially in places like summit racing Such as you see in that link. 7000rpm, 12.5 compression, and 600hp. Well, obviously that means they are strong.
The issue is that the RPM that a rod is operated at really is the determining issue with whether or not it will survive. Engines chuck rods, usually, because of a reving situation, not because of the power pushing on them. Its the pulling that breaks them.
Ah, but what about this? That spagetti on the left is not fron stretching. That thing was pushed into that shape. (BTW, if you can see the darker rod, that is what the 944 turbo rods are like, as well as the 87 and 88 rods on the 928. FWIW, a 1984 944's rods are FORGED, as well as the 86 turbos.
Sure, it woul dbe nice to find 8 944 turbo rods for my engine and be done with it. Unfortunatly, it looks as though everybody else is looking for them to, and the market is charging what it will bear.
The solution? I have two, and that is what I wanted to speak with you all about. I am already spending probably 6k on the engine before I put it back in, with the sleeving, the crank work, and pistons, and maybe head work (some smoothing/cam change/springs, etc).
So while this may sound "cheap", this is what I have found. If I had the extra cash, I would just drive down to Chula Vista, CA (south of San Diego), and buy a nice set of these for 1800 dollars. Cash and carry, no special sizes for the crank diamter, and the JE pistons being made aren't an issue either way.
.....or I could possibly save (several hundred?) by doing something crazy and getting a set of these. for 500 bucks, or similar.
Questions:
Can the big end of a forged rod be resized? The BE bore of a 944/928 rod is 2.165 inches. Many Chevy rods are around 2.10. Is there a readily available bearing that would be oversized enough to being the ID with bearing back to the required measurement of the crank journal? Or as I said, can the big end of the rod be resized to 2.165, and then I could use the stock bearings! Ah, but the rub is the cost. Resizing may bring me back up to the price, or close to the price, of the $1800 pauters. And what of strength? Are these mass produced chevy rods THAT strong? They sure as hell are cheap!
11-08-2003, 04:42 PM
#2
Pro
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Hey Brendan,
FWIW, here are my observations;
Did you see that the SB cheby rods are .206 shorter in length? These would be a solution, IF you were using a stroker crank, I suppose?
What is your intended use for this engine of yours?
Big ends are resized all the time, even to the point of shaving the rod and cap joint, so the rod can be resized to original.
Have you contacted anybody about Carillo rods?
You may wish to contact Summit, and several other rod manufacturers, telling them your parameters, lengths, widths, etc., to see what they might charge to make a "custom" set for you? Maybe see if they make a set of the SB rods for a 400CI SB engine, and see what it's measurements come to? Those rods are different from the rest of the SB engines.
Not being a ferd man, (although I do own a Dodge van ) you might also look at those, and any other hi-po engine rod builders' assortments of wares. They MIGHT be able to help you out, for a little more than that $499 price tag, being a "one-off" run? Much better than that 1800 price tag, for certain!
From my point of view, you still have a LOT of homework to do; you have raised more questions than you have asked. PM or IM me if you wish, computer is on...
'Nother thought just crossed my mind, how about these rods at Devek? (Ask 'em about your specific application for those rods, as regards to warranty, etc., if any... They have been there for a while....)
http://www.devek.net/index.php?page=..._sale_partsbin
Closer to you, an immediate fit, if you are using those year's of engines. In, out, and done, if you ask me...
You ARE going to use NEW rod bolts, right?
FWIW, here are my observations;
Did you see that the SB cheby rods are .206 shorter in length? These would be a solution, IF you were using a stroker crank, I suppose?
What is your intended use for this engine of yours?
Big ends are resized all the time, even to the point of shaving the rod and cap joint, so the rod can be resized to original.
Have you contacted anybody about Carillo rods?
You may wish to contact Summit, and several other rod manufacturers, telling them your parameters, lengths, widths, etc., to see what they might charge to make a "custom" set for you? Maybe see if they make a set of the SB rods for a 400CI SB engine, and see what it's measurements come to? Those rods are different from the rest of the SB engines.
Not being a ferd man, (although I do own a Dodge van ) you might also look at those, and any other hi-po engine rod builders' assortments of wares. They MIGHT be able to help you out, for a little more than that $499 price tag, being a "one-off" run? Much better than that 1800 price tag, for certain!
From my point of view, you still have a LOT of homework to do; you have raised more questions than you have asked. PM or IM me if you wish, computer is on...
'Nother thought just crossed my mind, how about these rods at Devek? (Ask 'em about your specific application for those rods, as regards to warranty, etc., if any... They have been there for a while....)
http://www.devek.net/index.php?page=..._sale_partsbin
Closer to you, an immediate fit, if you are using those year's of engines. In, out, and done, if you ask me...
You ARE going to use NEW rod bolts, right?
11-08-2003, 06:39 PM
#3
Brendan,
You've left a few variables out of this post, have you considered other "size" matters like width of the rods; they have to paired up within the crank journals. Small end press or floating (bushing in small end)? I believe stock 928 is full-floating and rod/piston selection could dictate pressed pins, but modifying to add bushings could be $$$.
Unless you hit on a rod that just happens to be close enough in all dimensions where only slight mods are needed, you going to end up eating any price advatage in machine work costs.
You've left a few variables out of this post, have you considered other "size" matters like width of the rods; they have to paired up within the crank journals. Small end press or floating (bushing in small end)? I believe stock 928 is full-floating and rod/piston selection could dictate pressed pins, but modifying to add bushings could be $$$.
Unless you hit on a rod that just happens to be close enough in all dimensions where only slight mods are needed, you going to end up eating any price advatage in machine work costs.
11-08-2003, 08:19 PM
#4
Three Wheelin'
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Brendan,
That twisted rod is similar to the one form my boat 650hp 460CI, water ingestion.
My project M28_44 engine has 944 rods #944 467 7171 ARST it looks stronger than 454 stock rods. Full floating pins are recommended for engines that operate under high loads and HP. If you are considering custom rods while using a stock crank have them made to the engines specifications,
That twisted rod is similar to the one form my boat 650hp 460CI, water ingestion.
My project M28_44 engine has 944 rods #944 467 7171 ARST it looks stronger than 454 stock rods. Full floating pins are recommended for engines that operate under high loads and HP. If you are considering custom rods while using a stock crank have them made to the engines specifications,
11-08-2003, 08:59 PM
#5
Rennlist Member
Thread Starter
Great Discourse.
Losing .2 of an inch off the rod is technically possible for me, as the pistons are not made yet, and will be suited to the compression ratio, bore diameter, rod length, yadda, yadda when that is finalized. Moving the wrist pin area down some will help with the fact that the enginewill eventuially be boosted to within an inch of its life.
Maybe a foot.
RE Devek, I didn't see that, and I will call them on monday. Thanks. I wonder what those rods are.
Jim - I DID forget about the Big end width, with relation to fitting correctly on the journal.... I did forget that.... Hmmm. That is a BIG variable, as changing the big end size AND the width could seriously undermine the structure of any forged rod. Thats alot of machine work when you add those two changes together on 8 rods.
Steve - Nice spagetti you had there on the boat engine. The 944 rods are something I need to do more research on.
'Course, I could get off the damn computer and go make the money I need to just buy the custom set and be done with this and on to the next issue!
Losing .2 of an inch off the rod is technically possible for me, as the pistons are not made yet, and will be suited to the compression ratio, bore diameter, rod length, yadda, yadda when that is finalized. Moving the wrist pin area down some will help with the fact that the enginewill eventuially be boosted to within an inch of its life.
Maybe a foot. RE Devek, I didn't see that, and I will call them on monday. Thanks. I wonder what those rods are.
Jim - I DID forget about the Big end width, with relation to fitting correctly on the journal.... I did forget that.... Hmmm. That is a BIG variable, as changing the big end size AND the width could seriously undermine the structure of any forged rod. Thats alot of machine work when you add those two changes together on 8 rods.
Steve - Nice spagetti you had there on the boat engine. The 944 rods are something I need to do more research on.
'Course, I could get off the damn computer and go make the money I need to just buy the custom set and be done with this and on to the next issue!
11-13-2003, 11:38 AM
#6
Rennlist Member
Brendan, have you checked out Sterling Gee's site? I believe it is www.928sq. He has pictures of the rods that he is using. Sorry for the delayed answer. I was interested in his before and after pics and had downloaded them to my computer. It took me a while to figure out where I got the images from. Good luck. John Curry
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11-13-2003, 01:44 PM
#8
Rennlist Member
Thread Starter
I have seen Sterling's engine (upclose at one point) and I do agree that I may have to either find forged rods 944 rods, or just buy a new set of aftermarket.
11-13-2003, 01:47 PM
#9
Rennlist Member
Thread Starter
These rods look a tad beefier then the 88+ rods on the 928:
http://cgi.ebay.com/ebaymotors/ws/eB...ory=33623&rd=1
There is more metal at the small end it seems.
http://cgi.ebay.com/ebaymotors/ws/eB...ory=33623&rd=1
There is more metal at the small end it seems.
11-13-2003, 05:53 PM
#11
Rennlist Member
Thread Starter
Are you going to be using chevy rods with your big crank?
11-13-2003, 05:55 PM
#12
Rennlist Member
Thread Starter
Can you go over to chat realy quick Adam?
Otherwise just PM me. Thanks
Otherwise just PM me. Thanks
11-13-2003, 06:31 PM
#14
Rennlist Member
Thread Starter
And here we have a Forged Rod from the early 944
http://boards.rennlist.com/upload/83rod.jpg
This is the orginal forged rod that the 83 944 NA recieved.
Hmmm.
http://boards.rennlist.com/upload/83rod.jpg
This is the orginal forged rod that the 83 944 NA recieved.
Hmmm.
