SuperchargedTundra

Are there any downsides of going with Ti exhaust valves from say Katech? I see a lot of people doing Ti intake but not many doing both

Z06_1

Cost is number one reason.

Long-term durability is number two (what works in a race motor that gets refreshed every few thousand miles is not necessarily the best choice for a 100K mile street motor).

Nuclear427

These are a very good option from Katech if you are willing to spend the $1,200. Katech uses Ti/Moly intake valves when customers switch to bronze valve guides because the factory Ti intake valves are not the best material to be rubbing against the bronze at high temps/pressures. The Moly coating on their Ti/Moly valves matches the bronze guides much better.

The reason you will see lots of their customers using the factory LS7 sodium filled exhaust valves in conjunction with the Ti/Moly intake valves is because they are steel and are compatible with the bronze guides.

Katech's combinations have all been thoroughly tested both in their labs and on the racetrack. In fact, I believe they used Ti/Moly valves in either the C5R/C6R ALMS cars and found excellent wear properties with bronze guides(Think thousands of miles of all out ALMS racing).

I would suggest calling Katech as they will be able to answer your questions much better than I can. My car will be going there soon for a cam and some head work.

American Heritage

Not really/sort of... but that depends on a few factors. Coating on the ti valve and seat material. When we do ti valves we either install Beryllium seat or Moldstar90 seats. This helps both the valve seat angles and the valve last longer. This also lead to much higher reworking cost. The ideal application would be for a race oriented vehicle but you can run them on the street if you like. Not sure this would be an ideal longtime fix for a street only vehicle but If done correctly ti should last a good while.

Bad_AX

I've come to understand that materials compatibility is a big issue when rebuilding LS7 heads. The OEM valves, guides and seats and coatings are carefully matched to endure durability, cooling/heat transfer and high performance. Most of us would probably agree that manufacturing quality from the various suppliers, not the engineering and design is the problem with the LS7 heads. The valve seats for example are made from very different materials for compatibility with very different valve materials. The overwhelming majority of LS7 head rebuilds use bronze guides, but I am not convinced they are the best solution when running OEM valves. What is your opinion on the compatibility of refurbished OEM intake valves and bronze guides? When these valves go back to Del West for micro polishing, are they also renewing the CrN coating, or just improving the surface finish of the existing coating?

Josh B.

Katech recommended to me either the Ti/Mo, or the OEM sodium filled.


Read in context, I understand your statement. But I would never arrange the words guides...carefully matched...durability in a sentence when describing the LS7 engine(s) that have been in my car.

Perhaps the materials/wear surfaces are part of the LS7 mystery? All 8 of my intake guides were toast

Bad_AX

Believe me. I understand that nearly everyone on this forum that has had guides properly measured has had some, if not all guides out of specification. I think its important to differentiate between engineering and design, and manufacturing and quality control. That is why I said,

Quote:

. . . . manufacturing quality from the various suppliers, not the engineering and design is the problem with the LS7 heads.

Josh B.

There doesn't appear to be a singular smoking gun, or even a pair of smoking guns, all factors apply, with each of their influence being greater than 0 but less than 100. You seem confident that it's not one dichotomy, but another dichotomy. The truth is that it's likely a sum of errors between engineering and manufacturing.

As I'm sure is common knowledge, Katech doesn't manufacture the Ti/Mo valve, Xceldyne does. It's not clear how Katech/Xceldyne is able to pull off a titanium intake valve feat that GM can't seem to, is it the engineering at Katech and the quality control of Xceldyne that is superior to GM? Is WCCH and their quality control installation of the valve superior? I like that Katech and WCCH will at least have a conversation about it.

I just say that it's hard to be confident what is or is not on the table for discussing LS7 valve issues. I am wrenching on my car today because it was not durable enough, that is why I almost choked on my gummy bear when I read the word "durability" in the description of the design of the LS7.

For pragmatism, until there are 100k mile examples of people running Ti/Mo exhaust valves, I am keeping the OEM exhaust valve. Not to say that it isn't possible, just that I want to go with what works, and what is known to work.

Rock36

One particular difference is that GM uses a CrN coating on the Ti intake valves with PM guides, and Katech uses the Mo coating with the Bronze guides.

Not implying this is any kind of smoking gun, but it is a difference in application.

Michael_D

Hey Kohle,

I'm curious... When you replace the exh seat insert, can you do so without having to replace the int? Or do you end up replacing both?

Personally, I would not run ANY Ti exh, no matter what the coating, without moving to a Moldstar90 seat. For the intake, it doesn't matter as much, but the MS90 seat would be better on the intake side too.

American Heritage

I always replace both the intake and exhaust valve seats on the LS7 heads when wanting to replace the exhaust seat. You could replace just the exhaust side but we replace both.

Michael_D

I figured as much... Seems kinda silly to not, seeing how the head is in the machine and set up for making chips....

Do you have a cost for this? Feel free to shoot me a pm or email if you prefer.

SuperchargedTundra

What makes Ti valves more usable on the intake side vs exhaust?

Michael_D

Heat on the exhaust side. The MS90 alloy provides two things; improved heat transfer, improved dampening.

Bill Dearborn

When I traded messages with Jason he recommended my using the Ti/Mo valves for both intake and exhaust. That recommendation was based on the higher amount of track duty my car sees. He thought the stock valve wouldn't hold up as well under those conditions. It sounds like a good solution but not a cheap one.

Bill

Katech_Zach

Actually in this case it is. The titanium valve with molybdenum-coated stem/bronze guide combo showed almost no valve guide wear after the 24 Hours of Le Mans, which is equivalent to at least 250,000 street miles. The heads out-lasted the life cycle of the other components.


This answers the question very well.

Bill Dearborn

Talked to an LS engine shop in Mooresville, NC today. They have rebuilt/replaced a number of LS engines including LS7s that have failed due to valve head drops. Every engine they have done has failed doing some sort of racing. They currently have an LS7 that dropped a valve head at Road Atlanta. The owner said they haven't seen any failures they considered were due to loose valve guides and in fact the guides were barely worn in several of the engines. I am driving out to see them tomorrow to get their thoughts on how to proceed from here. My impression talking over the phone is that he thinks the worn valve guide issue is blown out of proportion. He said the only way they will check the guides is by removing the heads and using the proper gauge to measure the guides. As for increasing the track durability of the engine he thinks Ti Valves along with Bronze guides would be the way to go if I decide to do anything.

Bill