LS7 - Anyone know what the EGT is?
Thread Starter
Teching In
Joined: Dec 2005
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From: Alaska
LS7 - Anyone know what the EGT is? 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.
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.
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.
Thread Starter
Teching In
Joined: Dec 2005
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From: Alaska
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.
Thread Starter
Teching In
Joined: Dec 2005
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From: Alaska
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.
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.
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?!?
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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.
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Teching In
Joined: Dec 2005
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From: Alaska
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.
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.
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.
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.
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?
