Ok, so instead of one pinpointed problem, I would be willing to guess that it might be a combination of all the things listed, such as... possible cooling issues, a crappy intake manifold, and an insufficient tune all on an engine that is not made for boost. I say this just because everyone is coming up with different reactions to the problem.

I would rather not run too cold of a thermostat because I am in places where it gets to around 0* at times during the winter. Would it be wise to go with a 180?

As far as the tune goes, with a mail order such as Nelson, I have no way of making sure that I have #7 tuned good except to tell him to make it a little fat. Therefore, I have to go to a local dynotune, which I just found btw, and hope he knows whats going on.

Ok, next question, I was poking around on summit and I couldn't find the Vic Jr. Can someone point me in the right direction of one of those. Would it be worth my time to use that insead of the stock intake manifold?

I'm glad I started this thread I hope everyone is learning as much as I am because this problem doesn't seem to be addressed enough.

 

Richard@WCCH has some Vic Jr.'s. I'm not sure but you might have hood clearance issues. I did but I also have a 90mm TB, luckily I had the cowl and with a little work it fit underneath. If your not sure about your tune guy I would think to just print this thread out and give it to him to read over. Also even though your in buffalo I'd head down to Mass and get some of the members on here to tune you up. There seem to be a lot of brain genuises over there and at least that way you have peace of mind. Glad a few of the rocket scientist chimed in on this thread, it's been really helpful.

 

The 99 and 2000 trucks (there may be more) had the four vent style coolant tubes. I had one on my 5.3, which broke number 5 & 7 ring lands due to kr.

And I am a believer that the intake is a huge contributor in most FI failures, just because Radixes see very few, but then again how many of those guys are running 14 psi?? What I don't get is WHY do just 5 & 7 fail, why not 6 & 8? Technically 8 is the rear most cylinder so it "SHOULD" be the first to go.. (With the intake theory of course) hmmm, maybe I just talked myself out of the intake theory.......

As far as running 14 psi, I can't really comment on that until I see what is causing my high crank case pressures lol. It isn't how much psi you are shoving into the cylinders, it is when you start your "burn". I bet you could run 30 psi of boost with a stock engine as long as you retarded the timing enough to keep the cylinder pressures in check.... Right?

If you are one of those people that feel the intakes are at fault, there are options other than a carb style intake, you could spray a ton of fuel (meth) down the intake to help feed the lean cylinders....

 

OK, so GM got it right. So, then there is nothing wrong with any truck or LSx GENIII/IV intake manifold, right?

You say the motors aren't made for boost then you turn around and say its normal (around "here") for 12-14psi on a stock motor... which is it?

Bill

 

Maybe both,(?) We all know they are not made for boost, but properly tuned they "could" handle 12-14 psi.
I don't really agree that there is nothing wrong with the intake manifold though...

 

Since you love to fight about it. Yes GM got it right.They make excellent power in stock form.Do you wish to fight that point too?

12-14lbs is no problem if you know how to tune and have enough fuel to support it.About 90% of the people here under fuel cars/trucks or do the typical 1/2 *** dyno tune which leans out on the street. My personal car runs 14lbs and has been doing so for almost 3 years,50 track passes, no knock sensors hooked up and a stock motor with springs.
To me it doesn't matter if no one believes it.We just keep doing our thing while rookie's keep disbelieving and blowing engines up.

Quote by Bill -You say the motors aren't made for boost then you turn around and say its normal (around "here") for 12-14psi on a stock motor... which is it?

It's simple,figure it out by yourself .I'm not here to argue.

 

The intake is crap for FI. But you can work around it by tuning off the rear cylinders and it will last a very long time.Most people look for the highest "Dyno" # they can find then get mad when there vehicle blows a piston.It's ussually inexperience with FI on the tuners side.

Of course a Carb style intake works alot better with evening out the air. Or another way is to spray Meth with follows the heavy air to the rear cylinders.

 

Oh come on Slow... not picking a fight Your statements are contridictory to, at least, me though. But thats nothing you or I will lose any sleep over. It all good You are apparantly one of few, the only one I know of, that can get away with 12-14psi on a stock motor for any length of time. I may not know much about tuning... but I do know a thing or 2 about fueling and putting motors together using stock intake manifolds... regarding fueling... you are spot on there. More often than not a truckload of money is spent on a motor and/or forced induction and little to nothing spent on fueling... let alone the rest of the drivetrain. I have seen it too many times and how it aggravates tuners...

Generally I am an inquisitive person. I like asking questions... and I like sharing ideas. Some are good and some aren't... and the ratio is probably no different than anyone elses that shares the experience. When I speculate I say so... when I voice an opinion I state thats all it is... an opinion.

This is an open forum man... we share ideas here... share problems here... ask alot of questions. Telling someone its "simple... figure it out yourself" is also telling everyone else creepin' in this thread to do the same. Its OK though...I don't take personally... after all this is the internet

Hopefully we can get this thread back on track so others are inclined to share their experiences here as well. I apologize to Slowhawk and everyone else if it appears I was picking a fight.

Bill

 

Well put. until we know...I run low boost, low timing, and a RICH tune.

If the intake leans certain cylinders , couldn't you have the injectors bench flow tested and fatten up those cylinders. I have heard of flow matching so some adjustments are possible.

SLOHAWK??? are you tuning off an o2 on one cylinder?


Yes ...I am looking for 1000hp on a 400 hp budget

 

Just curious on everyone who popped the #7, what kind of headders they were running? How about indexing the spark plugs?

I have a laser thermometer that I have shot on my headders after a dyno run and the #7 and #8 were always a little warmer (like 50-75* if I remember correctly). What does that mean?...could be alot of things but I never was too concerned. (running the 112 @ 9psi)

When I change plugs, I always look at # 7 a little closer than the rest