mdrew

I'm sending my heads out for overhaul and mild port work.

One consideration is to run Ti exh valves. After speaking with four of the most reputable Ti vlv sources to determine what I might need to do to the heads (seats, coating, finish), I was told to NOT run Ti in the exhaust on a street build if EGT's would be in excess of 1400 deg F where longevity was a primary consideration (and it is). Actually, 1400 was the max and it would be preferable to keep EGT's under 1400.

If I had a baseline from OEM, that would be most helpful as I will not be running an OE cam with the same exh opening point.

87silverbullet

iTrader: (11)

Trust me, you are not going to get to 1400*. Back in my old GN days we used EGT as a tuning reference and getting in the 1200* range was getting to the danger point. This was with a turbo car so I don't see a N/A car getting to that point. 11-1150 is where a GN needed to be if I remember correctly.

mdrew

Well....yes I know it doesn't sound probable, and I didn't give it much thought until I learned this particular engine does run a hotter egt than one might expect. I just haven't had much luck finding out what it actually does run. Closed loop, lower rpm is where it tends to run hottest.

ramairws6

iTrader: (33)

I was thinking about doing the same thing on the last go around but were told by many to not even waste my time!??

87silverbullet

iTrader: (11)

^^^Exactly,



Unless you plan or turning a ridiculous amount of rpm and need to keep your valvetrain light to control it, you will not need a Ti valve.

mdrew

I've been through the mental excersive of the pro's and con's and know them all well.

I like to figure things out on my own, verse following the crowd. Sometimes I end up following, but only after I detirmine they are going where I want to go.

ramairws6

iTrader: (33)

We're not talking about following any crowds here. We're talking about reputable shops and builders doing this all day long, not too mention guys that just do heads for a living. Now if you were running NASCAR style rpm's then i would say all in..... but a street driven car that you'll only rev to 6500-7000 once a year?!?

87silverbullet

iTrader: (11)

Lets put it like this, unless you have some kind of jacked up lean tune you will NEVER see 1400* so that = No Ti valve needed.

Unless you are going to constantly turn this motor past the 7500rpm mark you will not need a Ti valve.

So, in conclusion if your answer is no to the two things I just stated then again, you will NOT need a Ti valve.

Don't take our word for it, Call HKE, AES, LME, KUP, Billy Briggs and see what they say. They will tell just what we said.

If you don't want to take our advice or their's then just do like you said. Figure it out on your own.

mdrew

If I run a SS valve, it will be an additional 30 grams or so heavier than the oe sodium filled valve and about 25 grams heavier than the Ti intake. That is a considerable addition to a motor spinning 7000+ rpm (and yes, I have seen + 7000 revs). If there were an aftermarket hollow stem, or hollow stem sodium filled valve available, that would be preferable. Neither are available with the exception of the OEM valve, unless you go to Ferrea and have them do a batch run of 100 valves or more.

Adding spring pressure and running lighter short travel lifters will enable the valve train to run at oem rpms, but why do that if it can be avoided? A lighter valve train is always preferable to compensating with spring pressure.

I've spoken to WCCH, AI, Linernoise, AFD, RPM Motors, Rehre Morrison, Texas Speed and I have also had conversations with a program manager for one of GM's aftermarket racing department, as well as Ferrea, Trick Ti, Del West and Xceldyne. Each one has there own opinions and recommendations.

I'm just flushing out my options guys.

87silverbullet

iTrader: (11)

Wait, wait, wait, look at what you just posted in your middle paragraph. To run at OEM rpms? OEM rpms are 7000 in an LS7 and putting bigger springs and lighter lifters will take is past the OEM limit. All tose people you mentioned are good people but you need to talk to the engine builders on this site. HKE (Erik Koenig) KUP (Kurt Urban) Billy Briggs. Those guys build this stuff everyday and know what works. They run some of the motors they build on engine dynos and know what it takes to make a valvetrain live in certain applications. I have talked to Erik Koenig of HKE and he stated my setup will be ok and I will see 72-7500 or more on the bottle. I have L92 heads with the stock L92 valve and stock upgraded rockers and .650 lift Precision Rcae Component springs.

Lets start over. It seems you are trying to kill a cockroach with a bazooka here. What kinda car is this and what is the intended usage? Are you road racing some kinda car that will see 8000+ rpms on a roadcourse or is this a street car that will have a H/C pacakge and will see the occasional track romp?