LS7 Titanium Connecting Rods
Safety Car
Joined: Sep 2001
Posts: 4,157
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From: Glenbeulah Wi
If you have them and want to run them why not? It would require a custom piston to deal with the 6.067 length and .925 pin diameter but it could be done. You could bore the small end to .927 or you could just have the .925 pin used on the custom piston.
Last edited by bjankuski; Feb 18, 2018 at 10:18 PM.
Safety Car
Joined: Apr 2005
Posts: 3,624
Likes: 431
From: Dale City VA
Its not a big job to run them. LS use no offset on the big end and the small diff in pin size compared to the SBC. Length is slightly longer than common SBC aftermarket 6"rods.
This is just the way I would do it:
I would narrow the big ends to about .900 wide and run piston guided rods... requires custom pistons but... I dont think you would have to do it that way... most likely even with no big end offset they will work with normal shelf sbc pistons.. just the pin end will be now be offset on the pin on the piston.
I would hone the factory little end bushings for .927 sbc pins.
I would not worry with the length difference. If you go with custom pistons easy to fix if you want to. Also easily adjusted with block deck height and headgasket if you run shelf SBC pistons.
Will
This is just the way I would do it:
I would narrow the big ends to about .900 wide and run piston guided rods... requires custom pistons but... I dont think you would have to do it that way... most likely even with no big end offset they will work with normal shelf sbc pistons.. just the pin end will be now be offset on the pin on the piston.
I would hone the factory little end bushings for .927 sbc pins.
I would not worry with the length difference. If you go with custom pistons easy to fix if you want to. Also easily adjusted with block deck height and headgasket if you run shelf SBC pistons.
Will
Safety Car
Joined: Apr 2016
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From: N.E. Ohio OH
Finalist 2020 C4 of the Year - Modified
With the less reciprocating mass titanium has, I assume your engine revs pretty quick ? Unless you truly had before and measurements with some pretty sophisticated mechanical means, I would say that your brain is quick enough to know that it revs quicker.
So how much would you guess ? (we all know a 2 cycle 100 cc engine revs quicker than a 4 cycle and we can hear and feel it.
This is an honest question, thanks.
So how much would you guess ? (we all know a 2 cycle 100 cc engine revs quicker than a 4 cycle and we can hear and feel it.
This is an honest question, thanks.
Race Director
Joined: Sep 2001
Posts: 14,680
Likes: 752
From: NEwhere Ohio
With the less reciprocating mass titanium has, I assume your engine revs pretty quick ? Unless you truly had before and measurements with some pretty sophisticated mechanical means, I would say that your brain is quick enough to know that it revs quicker.
So how much would you guess ? (we all know a 2 cycle 100 cc engine revs quicker than a 4 cycle and we can hear and feel it.
This is an honest question, thanks.
So how much would you guess ? (we all know a 2 cycle 100 cc engine revs quicker than a 4 cycle and we can hear and feel it.
This is an honest question, thanks.
Thread Starter
Le Mans Master
Joined: Feb 2005
Posts: 6,482
Likes: 566
From: Clearwater Florida
With the less reciprocating mass titanium has, I assume your engine revs pretty quick ? Unless you truly had before and measurements with some pretty sophisticated mechanical means, I would say that your brain is quick enough to know that it revs quicker.
So how much would you guess ? (we all know a 2 cycle 100 cc engine revs quicker than a 4 cycle and we can hear and feel it.
This is an honest question, thanks.
So how much would you guess ? (we all know a 2 cycle 100 cc engine revs quicker than a 4 cycle and we can hear and feel it.
This is an honest question, thanks.
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Thread Starter
Le Mans Master
Joined: Feb 2005
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From: Clearwater Florida
..... I have less than $1000 in these rods including $220 worth of ARP Bolts and all machine work ... and these are lighter than aluminum rods by 40g with no known or assumed expiration date like aluminum rods ... besides the alloy rods are pretty massive size-wise and would not likely work in a stroker engine due to cam and oil pan rail clearance issues .....
Safety Car
Joined: Apr 2016
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From: N.E. Ohio OH
Finalist 2020 C4 of the Year - Modified
Thanks I was just curious. When I was in my early 20's, I worked in a defense shop doing high precision machining. I made a lot of parts out of titanium for various types of sophisticated weaponry, satellites, etc.
I remember how light it was -vs- the same size piece of steel. I simply wondered if it revved quicker due to the less weight the crank was lugging around with itself.
I remember how light it was -vs- the same size piece of steel. I simply wondered if it revved quicker due to the less weight the crank was lugging around with itself.
Team Owner
Joined: Oct 2004
Posts: 81,241
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From: altered state
St. Jude Donor '05
Never could feel a difference doing lightweight rotators
20 lbs off the FW was slight. Sometimes wtih increased strength comes weight. Kinda like adding a rollcage to stiffen up the chassis. Theres good weight and bad. hard to feel a difference with or wihotu a 100 lb passenger (but life is cheaper w/o)
C409 any clearancing issues with the block?
20 lbs off the FW was slight. Sometimes wtih increased strength comes weight. Kinda like adding a rollcage to stiffen up the chassis. Theres good weight and bad. hard to feel a difference with or wihotu a 100 lb passenger (but life is cheaper w/o)
C409 any clearancing issues with the block?
Le Mans Master
Joined: Oct 2002
Posts: 7,098
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From: Las Vegas - Just stop perpetuating myths please.
..... I have less than $1000 in these rods including $220 worth of ARP Bolts and all machine work ... and these are lighter than aluminum rods by 40g with no known or assumed expiration date like aluminum rods ... besides the alloy rods are pretty massive size-wise and would not likely work in a stroker engine due to cam and oil pan rail clearance issues .....
. But there are some reasonably priced Al rods compared to Ti rods so I had to ask.
Le Mans Master
Joined: May 2004
Posts: 5,386
Likes: 534
Sounds like no major worries if you've been running them over 4 years. A set of these and a set of custom pistons will bring you in way under a $8,000 set of sbc Ti rods ready to drop in. I'd be dumb enough to give it a try for the cool factor alone.
Safety Car
Joined: Apr 2016
Posts: 4,648
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From: N.E. Ohio OH
Finalist 2020 C4 of the Year - Modified
I'm very surprised the Ti rods are lighter than Al rods though the Al rods do need more bulk.
Last edited by drcook; Feb 19, 2018 at 10:38 PM.
Thread Starter
Le Mans Master
Joined: Feb 2005
Posts: 6,482
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From: Clearwater Florida
..... Dart Little M Block ... No block clearance problems , but I had to remove a little bit of shoulder on rods 1,2,5,&6 for camshaft clearance ... and that's with a .920 base circle cam ... Having spent some time grinding titanium , I can tell you first hand that its some hard s**t .....
Safety Car
Joined: Apr 2016
Posts: 4,648
Likes: 1,059
From: N.E. Ohio OH
Finalist 2020 C4 of the Year - Modified
Having spent some time grinding titanium , I can tell you first hand that its some hard s**t
Thread Starter
Le Mans Master
Joined: Feb 2005
Posts: 6,482
Likes: 566
From: Clearwater Florida
..... This engine was built around these rods ... I was going to build a 406 until I became aware of the LS7 titaniums ... seems most LS7 builds wind up with steel rods and the Ti rods go under the workbench ... I used a 3.875" crank with Mahle pistons intended for a 4.00" crank (1.000" compression height) ... with a 9.00" deck , the pistons were just barely out of the hole ( .005") so I used an .051" compressed head gasket for a little extra clearance up top ... The new version will have custom flat top pistons with 0.990" CH to get the piston back down in the hole with a lot less compression ... around 12.0:1 vs 13.4:1 with the domes ... also had to accommodate the "meaty" pin end of the rod ... the Ti rods are roughly .250" from the top of the wrist pin to the top of the rod ... most steel rods are about half of that ... another custom option was to go with a smaller ring package using 1mm , 1mm , 3mm instead of 1/16" , 1/16" , 3/16" ... this should help with the reduced compression height ... My intent is to put this on the Stuska engine dyno for break-in and to see what kind of power it will make .....
Le Mans Master
Joined: Aug 2015
Posts: 6,118
Likes: 1,994
From: St. Charles MO
Thanks I was just curious. When I was in my early 20's, I worked in a defense shop doing high precision machining. I made a lot of parts out of titanium for various types of sophisticated weaponry, satellites, etc.
I remember how light it was -vs- the same size piece of steel. I simply wondered if it revved quicker due to the less weight the crank was lugging around with itself.
I remember how light it was -vs- the same size piece of steel. I simply wondered if it revved quicker due to the less weight the crank was lugging around with itself.
The advantage of lowering reciprocating mass (as opposed to lowering rotating mass) is mainly to increase durability and/or the safe redline speed of the engine. Lowering rotational mass does improve "revability," if you will. But spending money and reducing strength of the internal parts to accomplish that is misguided. Remember, rotational inertia is determined not only by mass but also by the radius of the center of that mass. The crank and big ends of the rods are rotational mass, but their radius is very short, so they don't contribute much to rotational inertia. By far the biggest contributor to that is the flywheel or flexplate/TC.
Team Owner
Joined: Aug 2004
Posts: 21,543
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From: Park City Utah
When the Flat plane GT350R came out, everyone just about blew a nut over it's "light weight, fast revving crank". While the crank was slightly lighter than the standard cross plane crank, THE FANCY CRANKSHAFT ACCOUNTS FOR LESS THAN 15 PERCENT OF THE V-8'S ROTATING INERTIA (a little over a 1/3 of the way down)
It's ALL about the flywheel and clutch. Want a fast revving engine? Install a flex plate and a tiny diameter, stock-car style multi-disk clutch. Even with a heavy cast crank, stock rods and heavy stock pistons...this set up would make any V8 seemingly rev like an F1 engine....
.
Last edited by Tom400CFI; Feb 22, 2018 at 01:29 PM.