Blownolds

Hello all, I guess I'm new to the board.

I thought I'd poll you offshore powerboat endurance racers about titanium connecting rods. I'm hearing totally conflicting things about them, such as they break, or they don't break, back and forth and so on. I'd sure like to be able to figure out if they are suitable or not for an endurance engine that is supercharged, with the rods capable of handling 1000HP (I expect 800-850 in reality, but prefer rods that will live with no undue fears). I'm guessing that perhaps titanium rod technology has advanced over the old days, just like aluminum rods, with better alloys, better manufacturing processes, and better heat-treat processes. But before spending a wad on ti-rods, I really need to hear from those who are using or have tried them.

So, anyone here successfully (or unsuccessfully) using titanium rods? If so, what engine application exactly? How long have you been using the same set? RPM they see? Other specs of the engine? Type fuel? Manufacturer of the rods? How about bearing wear or bearing life? Any other things that should be discussed?


Thanks.

mcollinstn

Let me preface this to say that I have NO EXPERIENCE with titanium rods.

What I do know, however, is that pound for pound, titanium is hard to beat for strength. With that said, it is notable to recognize that a lot of popular titanium alloys do not have as good of a fatigue life as high-chrome steel alloys such as those used in hi-perf steel rods.

For a sprint motor, titanium can offer a lot in terms of balancing strength against reciprocating weight and its associated loading cycles. For an endurance motor, I am not sure of whether a connecting rod is the best application.

Remember, I have ZERO experience with Ti rods, so I am only offering something for you to discuss with your builder/parts suppliers.

** Hopefully, this thread can bring positive information to us all.

PatriYacht

With a boat motor the weak link is in the valvetrain. Bottom ends built with good components are good for 7500 rpms for hours on end. However the big roller cams required to feed a big engine at these rs will kill lifters and springs. Why spend all that money on something you won't get any benefit from?

Blownolds

Application I'm considering them for is a supercharged engine that will not be taken apart all the time, hence aluminum rods are out of the question. Being supercharged, lift will be no more than .650-.670 maximum, and is a shaft-mount setup, so valvetrain probelms should not be an issue.

Keep the input coming, thanks.

Dave F

You can exceed a 1000 hp easily on quality "of the shelf" 4340 rods all day long from someone like Oliver, Lunati etc.

That being said, I agree with partiyacht

DAVE

GeeterB

How about Titanium Valves??? Would they be suitable for the marine environment??? Will they last???

Blownolds

The strength of the steel rods wasn't the question, those are obviously stronger than aluminum rods. The problem with the steel rods is the weight that is being slung around being very hard on the bottom end of the engine at 7000 RPM (which is one main reason why drag engines use aluminum rods).

Since aluminum rods will not be a good choice in an engine that is not torn apart regularly, and because of the weight of stel rods being a negative factor in a blown engine at 7000 RPM, this is why I am investigating the titanium rods.

I just need to determine what people's experiences have been with titanium rods. I've heard conflicting things, and I suspect there are differences in alloys, manufacturing processes, and heat treats, just as with any steel and aluminum rod. Not all rods are equal in steel and aluminum, so I suspect titanium won't be much different. But I have heard of a few reports of cracked ti-rods, which makes me nervous about investing in them until I can get some input from those who use them successfully.

Anyone have experience with Oliver's forged titanium rods which are of a different alloy than the typical 6-4 and are forged instead of billet? Anyone know of any endurance marine racing engines using titanium rods, or have any references I can contact?

Mbam

How many hours do you anticipate between teardowns?

puder

oh lord here we go. Marc biult a air fo 1000 and ran for godknows how many hours...

wasn't it somehting ridiculous like 500 before a rebiuld?

Blownolds

I personally would like an engine to last 1000 hours between tear-downs if possible. I certainly would hate to have to replace a $3800 set of rods every 1000 hours, or even 500 hours. But will still easily consider titanium over steel if they will hold up for 1000+ hours.

I spoke with a tech person at Sonny's Racing Engines today and he told me they have been using Crower Ti-rods exclusively for 10-11 years with no reports of any failures at all. He said Sonny's uses the Ti-rods exclusively in their 800+CID IHRA Pro Stock mountain motors. These engines have 5-1/2 to 5-3/4 strokes, run 800-8300 RPM, and produce 1700 HP. He said those engines run 80-90 passes per year, and several have had the same set of rods for 4-5 years. They only use the best high-priced rod bolt option, and they do change out the rod bolts at about the 3 year mark. He also stated there were no problems whatsoever with bearing wear and bearing life. So that makes me think they would definitely be suitable for a blown gas engine running a 4" stroke, 7200 RPM and 1000 HP.

Except for two things:

1)Those IHRA pro stock engines are still drag engines, and the actual number of cycles on the rods are still low in comparison to an engine that is run for long periods of time such as in an endurance application, street application, or other non-drag applications.

2)He also stated that Sonny's does not use Ti-rods in NOS drag motors because of the severe shockload the rods receive on the launch of a NOS-assisted drag car. They use aluminum rods for those engines. Even still, he said there was a man in KY running a Sonny's ex-pro stock Ti-rod engine on NOS with no problems reported. Sonny's had no first-hand experience with supercharged engines, but did say that blown engines are easier on the bottom end at the launchpad in a drag car than NOS-assist since the RPM is not at max RPM and the blower is not yet being driven to its potential until a little later.

So, I'm still trying to nail it all down as to whether a high-quality Ti-rod will be suitable for a 1000HP blown gas engine that will be run for hours before being torn down, unlike drag-only engines. Any further input as to experiences of Ti-rods is still greatly appreciated, thanks.