Tony @ Mamo Motorsports

Guys,

I've got alot to say here and will try to do so in as reasonable amount of space possible but I have alot to cover so buckle in. In fact this post is over the 10,000 character allotment and it will be broken into two posts as there is nothing here I want to remove.

Hollow stem valves.....I would venture a guess that no other shop has used as many as I have in the last 20 years. Im actually fairly confident that's a factual statement.

Since 2003, 85 - 90% of the heads I have shipped have hollow stem intake valves (some even have hollow stem exhaust valves as well).....the other 15% a mix of titanium and solid stem.

The first company I dealt with on the hollow stems was REV and I purchased these valves from them steadily from 2003 till late 2017.....call it 15 years. It started out small while I was heading up the R&D Dept at AFR helping folks looking for heads that were a little more custom in nature offering more flow and power potential than the out of the box stuff I designed at AFR. My point is maybe between 2003 and 2010 I probably shipped on average only 40 sets a year. Between 2010 and 2015 things picked up and that grew to 50 - 60 sets a year. And since doing this full time in late 2014 when I launched Mamo Motorsports, 100+ sets a year comfortably.

Lets do the math on the 15 year run of REV valves....7 years at 40 sets.....5 years going on the low side at 50 sets.....then 2+ years of larger volume (100 sets annually) when I did this full time. That's 730 sets of heads since 2003 and we will use the lower 85% figure for the number of hollow stems multiplied by 8 valves per pair of heads just counting the intake valves (a much lower percentage had hollow exhaust). That means I shipped almost 5000 REV hollow stem valves over that 15 year period.....(the math came to 4964 pieces). In that large span of time I went 15 years without a single failure that I could clearly point to as being a manufacturing defect. Others that broke had clear signs of P to V issues, the infamous #7 piston grenading and taking out a bunch of parts with its break up, etc. Then in 2017 I experienced a few failures much like what Troy (Big Daddy) experienced here. A stem completely broken clean in the middle where its actually protected and supported by the valve guide. This was a very different type of failure and it become clear to me looking at the half still in perfect shape (the top portion of the stem), that this failure happened due to a bad friction weld. I don't want to get into this too heavily but cliff note version is these valves are made in two pieces....the top half of the stem and the valve head and lower stem portion. This way your not drilling from the top four plus inches giving the drill alot more travel to walk and create a thinner and thicker wall. Having to cover only half the distance starting with two pieces reduces the amount of "drill walk" which creates the hollow center portion by a large margin. Then the two pieces are "friction welded" together which is a process that is pretty much what it's name implies. The lower and upper portion of the hollow stem valve (after its gun drilled to remove the weight) are spun at very high speeds and while spinning pushed into one another with alot of machine generated force. The "friction" and the heat that is created by this process ultimately fuses and welds the two pieces together without requiring any type of filler rod to do so. Done properly, the weld is actually stronger than the parent material because its thicker there creating a "donut" of fused stainless steel that is then carefully machined on a CNC lathe to set the final finished diameter of the valve stem (Note that prior to and during the welding process the stem is left purposely larger than the final dimensions call out). You normally can not see any signs of this weld after the final machining as for all intensive purposes its one and the same metal....not even filler rod to discolor or show anything different in the area of the weld. However, in a friction weld gone bad, these valves will break cleanly at the weld and you can still see the inside showing some signs of the donut or fusing of the metal because its not machined like the outside is with the final manufacturing processes. I haven't seen Troy's valve in person so I cant say for sure that's the situation here but from the handful of pictures I have already seen it certainly looks to be the case. I'm also fairly certain that his last failure was related to other causes and I say that because my experience with the few hollows that have failed like this (at the friction weld), happened almost immediately (very little run time) much like Troy's did.

So getting back to my hollow stem purchase history....why did I move my business to Ferrea after having such a long proven track record with REV. It became obvious the REV situation was not an isolated event. I had three similar failures inside of 6 weeks and REV wouldn't accept any responsibility at all, offer any help whatsoever and ultimately stopped responding to and began ditching my phone calls. Fifteen years and six figures worth of business was apparently not worth much to these guys and that was the deciding factor that pushed me to look into working with Ferrea with the added benefit to that of working with a company that has a much better reputation in the industry any way. That said, looking at things at pure face value, it was hard to argue with the proven results and track record I had with REV hollow stems for that long period of time. Also, their valves were lighter than the competition and I had a 15 year run of zero "manufacturer induced" failures. But their handling of things when we had our first run of problems was a complete turn off not to mention a nightmare for me barely two years into running my own business. I had to track down all my customers that were running valves from that batch (luckily a fairly new delivery so maybe 20 customers) and I contacted all of them and ultimately replaced them with Ferrea valves helping them with the labor required to swap out the valves and paying for the replacement Ferrea hollow stems as well).

That was four or so years ago and I have been much busier since all four of these years have been fulltime as Mamo Motorsports. I figure based on my conservative figures I have about 3200 hollow stem Ferrea valves out in the field since switching over from REV....Troy's very unfortunate situation would be my first failure with one of their hollow stem valves that looks like it could be a manufacture's defect (I would need to see the head of the valve in person to say that with a higher level of confidence). For what its worth in 2013 I built my 2nd Gen 2 CTSV with OEM LSA heads at the time that I fitted both sides (Intake and exhaust) with hollow stem REV valves. It's a mild boosted build that makes about 700 RWHP and I have put 36,000 miles on that car since modding it with those valves installed. Point is I believe in the technology and run the same style valves in my personal vehicles and I believe they are cost effective and not prone to failure having a huge personal data base almost 20 years in the making to confidently say that's true.

CONTINUED IN NEXT POST

Tony @ Mamo Motorsports

Important history and actual supporting data behind us....what happened with Troy and I regarding the falling out of a customer I have worked with numerous times before. He originally hit me with pics of the top of the broken valve in a text. My heart sank when I saw that and I feared his motor was going to be trashed....in fact in my mind it was almost a guarantee. The three failures I had with the REV valves were catastrophic in nature as you would imagine they would be when the entire head of the valve and half the stem attached drop into the cylinder. We got on the phone at one point and he said that they thought there was minor to zero damage and the other half might still be in the valve guide?? I was amazed to hear there wasn't already obvious signs of major trauma and was thinking could he get this lucky to have experienced this type of failure without complete carnage? I followed up a few times via text but it took them a little while to get the head off. When they finally did I was amazed how little damage there actually was and tried to convey that to him but I suspect he wasn't ready to hear that yet (how "lucky" he was) and it likely came off all wrong when I was sincerely feeling like if this same scenario happened fifty times, forty nine times out of the fifty, the complete engine and the heads would mostly be trash and not repairable. I really didnt get into detail yet on what I was willing to do to help because I didnt have the opportunity to do so. We were discussing at first getting me some better pics but then I realized Ferrea is going to want to see the valve and more pics is a waste of time so I offered to send him a label to get the valve pieces to Ferrea as that is the first thing I needed to do to see if Ferrea is or was willing to help us in any way dictating some of what Im able to do also. At the very least I would have helped with the labor on the head repair and provided him with a new replacement valve....given him Ti valves at my cost of he wanted to upgrade, etc., etc....anything reasonable would have been on the table.

Anyway....Troy was upset and rightfully so but he basically told me he was "done with me" in no uncertain terms and was blaming two engine failures on me personally or at least that's how it felt to me. I don't feel either scenario was defective workmanship from myself or Mamo Motorsports. Am I or was I willing to help in this situation.....absolutely had I been given the chance, but part of that is having an understanding that this was not something I could have done anything differently to avoid. I installed parts from a premium manufacturer that I have never had an issue with. The heads were built and machined properly and this engine showed great promise in the brief time it was running. What happened clearly sucks but this is racing and your dealing with mechanical components that no matter who's name is on the box is not going to give you a guarantee it wont break. As a general rule the better the quality and company reputation the more expensive the part and the better your chance of reliability is going to be but lightning can and will always strike. And don't think Ti valves are the magic "unbreakable" lightweight valve option either....spend a little time on the C6Z06 forums.....plenty of engine carnage their to see mystery titanium intake valve failures and destroyed motors.....too many to count in fact.

So here we are.....nothing has changed on my end. Im still willing to help get these heads back in perfect working order if given the chance. Troy if you have had a change of heart and that is something your willing to consider reach out to me and we can discuss this in more detail on the phone. If we do move forward with this I would want to inspect the valve pieces myself and then I can send them to Ferrea for their evaluation.

Sorry this post was so long but there was alot to cover and I wanted to be as thorough as possible considering the gravity of the situation

Regards,
Tony

ddnspider

iTrader: (26)

Interesting back story. Would love to know what Ferrera says. 3 out of 5000 and potentially 1 out of 3000 doesn't sound great as far as failure rate as nobody wants to be the "one", but in terms of percentage it's actually quite good. Usually in these situations, how the vendor chooses to handle the failure and fixing the issue speaks volumes about them. Given the level of detail and cost (these aren't a run of the mill stage 1 ) I would hope the customer would be taken care of.....but they have to give the vendor a chance to make it right.

jasons69chevelle

if the valve failed at the locks/retainers
I’d like to see the area under the locks of the rest of thevalves. Inspect them for deep scratches or nicks.
friction welding is definitely a good process it actually forged the two pieces together. I built driveshafts at Ford for a few years. Weakest area is the HAZ heat affected zone.

BigDaddy97

Again as previously stated, I'm not here to "rag" on Tony. I've spent over $12k with him over the past few years and at this point I've made a firm decision to go elsewhere. I don't wish to pay him additional money for repairs and valves. I ran a custom computer business for 30 years, and the couple of times I did have a return for a failed part, I replaced the part out of my own pocket and then worked with the part manufacturer to get reimbursed. Sometimes they did and sometimes they did not, but I kept the customers future business. Not everyone does it that way but that's how I did it.
Seriously though it's done and over with and I don't wish to keep talking about this. I will purchase another set of heads, rebuild the shortblock, install a CID/4500 setup, put this behind me and move forward. Thank you.

G Atsma

The way it sounds, you need to at least see what Ferrea, and in turn Tony, will do for you. You're not even giving them a chance. Both Ferrea and Tony have an excellent rep for taking care of their clients. You might have ended up with very little out-of-pocket expense. But now you will never know, and will always bear ill will towards the undeserving.
Too bad, really

BigDaddy97

Sorry but we did talk and he told me what he was willing to do. I'm just not gonna agree to sending him anymore money.

BigDaddy97

Moderators please lock this thread. Thank you

Launch

While the thread is still open, curiosity got me. Why is there 2 different pistons with damage? As i read it, only one intake valve broke?

Launch

Either the valves are faulty or they hit the pistons.

If 2 different pistons are damaged , then i'd say the intake valves hit the pistons from either: valve float, or the valve stems binded in the guides (seems unlikely), or ptv wasn't sufficient but doubt that as you said it was checked.

Just trying to help. It'd be good to know what caused it so it's not repeated.

I'm reving my junk to 8k rpm, titanium valves all 16 of them. Forgot what brand, the heads are ex 24hr daytona nascar. I think they were the xyldynes. I'm using .072 thick lash caps.

There's a chance ferrea quality has gone bad. Ebay has lots of new & used titanium nascar valves cheap. I think also i read that someone also cuts them down to whatever length you need.

You could replace all the intake valves in Tony's heads with titanium and run it. Titanium is lighter has less chance of valve float with same springs. Another reason the nascar engines use 7mm and 6mm valve stems, even less weight and also less friction.

BigDaddy97

Only 1 piston is damaged.

Launch

My bad, i see it now, the 2nd pic is with the head of the valve sitting on the piston. I skimmed over it too quick and thought it was 2 different pistons with damage.

Anyways i hope you have better luck with the next build.

ddnspider

iTrader: (26)

I was not attacking you or saying you didn't do your part. I wasn't even sure you were the customer going elsewhere as I haven't kept up on here much. Best wishes for your rebuild and choice.

JRFed

Sorry to hear this man , I'm not a fan of hallow stem valves epically with a heavy rocker system. #1 reason why I will keep preaching to avoid heavy rockers with hallow stems. Good luck on the rebuild and if you have any valve train questions I'd be happy to help.

ddnspider

iTrader: (26)

Dumb question as I don't live in the high end NA world. Is there really that much power to be gained from a hollow stem valve as opposed to solid, all else being equal? Or will it extend the rpm range that much to make it worth it?

Last 1

iTrader: (2)

I would think that reducing the weight in the valvetrain would help so YES.for street used a titanium valves is just a over kill to ME. But I just have a street car .I’ve been running Ferrea hollow stem valves with no issues Yet.myself I just don’t buy into titanium valves for the street.Imo.(race car different story)

QwkTrip

iTrader: (23)

What's too bad is all the barking from the sidelines. This isn't a matter of right and wrong. It's just a choice of what he wants to do next and he's made his choice.

01CamaroSSTx

iTrader: (3)

The C6 Corvette Z06's come stock with titanium intake valves and the supercharged LS9 also has titanium intake valves. The material is lighter, more heat resistant and stronger which is a plus and the reason for the high price tag. The only upside to all of this is that OP can make it better, stronger and faster.

BigDaddy97

Absolutey right, I've had an incredible run of bad luck, but this hard headed old man will not yield until I'm back in the winner's circle. The engine came out today and is going to the machine shop tomorrow for a replacement piston and sleeve from HPR. I bought a set of much lighter rockers and also purchased a super nice set of heads with titanium valves from a guy who ports for the pro stock guys. The 4500 throttlebody and CID intake will be ordered later this week.

Che70velle

iTrader: (6)

Long baseball weekend and purchasing a crazy low mile Z06 has kept me away for a few days. Glad to see Tony post up and give his input on hollow stem failures, which I’m not sure anybody out there is using very many more hollows than he is. Going by the numbers guys, this is simply a very rare and unfortunate failure for BigDaddy. A positive to take away from this that a piston and a sleeve puts the shortblock back together. I’ve seen C6 Z’s idling at red lights, drop a valve, and the end result is catastrophic failure. Only thing saved is a crank, front and rear covers, valley covers, intake, and valve covers. There’s a a couple of these in-car real time videos on YouTube, look it up. It’s crazy what a valve head can do when it falls into a cylinder idling, much less at 6500 as in BigDaddys situation here. Pretty fortunate really to be able to have “minimal” damage here while drag racing. We had Cup engines come back to us 30 years ago that dropped valves, and it was nothing but shrapnel inside every time. Oil pans look like a 12 gauge shotgun with 00 buckshot hit them from 15-20 feet away. Just freaking carnage, nothing left.
Tonys customer service is second to nobody’s on the industry, and in my opinion I believe that given a chance in this situation, this could have been rectified quickly and as painless as possible. BigDaddy has chosen to take his business elsewhere, and that’s his choice guys, so this case is settled. It is what it is. Troy (BigDaddy) has asked me to close this thread for him.