So I'm replacing the OEM headers on my Sequoia (4.7L V8) because they have the typical cracked flanges. This is a pretty involved job thanks to 15 years of rust and tight working conditions to get to some of this (and having to cut off rusty exhaust as well). Anyhow, I'm going to tackle it tomorrow but may or may not have enough time to do both of them before dark. I need to tow with the truck this weekend about an hour away.
- the headers are "shorties" so while they supposedly flow better than the OEM ones, they are generally similar in design (no cats eliminated or anything like that).
So the oddball question: What if I only have time to do one and need to drive the truck before I can do the second one? Will it hurt anything to do so?
This is all theoretical, and I hope to take care of both before the weekend, but figured I'd ask. More curious than anything else.
Mr_Asa
UberDork
4/27/21 11:18 p.m.
Probably try and throw a code. Once side might be a little bit more efficient than the other, so it might try to do some weirdness with the fuel-spark map to try and compensate. Long term that might mess with your cats, but if you're looking at just a weekend I don't think it would hurt anything.
bgkast
PowerDork
4/27/21 11:26 p.m.
I bet you won't be able to notice.
We took a stock manifold from a Toyota 3.4 and welded a turbo flange on it with a T3. Left the other side stock. Ran that way for years and years - we may have put 100k on it before we sold it. Next owner drove it until it was wiped out by a drunk.
There is a zero chance if that causing an issue.
There is a reason I asked this question. I did the "one" today (the cracked driver's side one). It was hellacious. I'd rather do a dozen engine swaps on the e30 than do the passenger side header on this thing. But, maybe next week...
Keith Tanner said:
We took a stock manifold from a Toyota 3.4 and welded a turbo flange on it with a T3. Left the other side stock. Ran that way for years and years - we may have put 100k on it before we sold it. Next owner drove it until it was wiped out by a drunk.
Just out of curiosity, what was the rationale for only doing one or not doing it downstream after the merge? Not sure I've ever heard of anyone putting a turbo on only one bank of a V-engine, but can't say I really pay attention to that stuff.
Definitely interested in the answer to this!
I'm surprised that no one pointed out that you'll just end up driving in circles since one side of the engine will be making more power than the other.
I think you'll be fine. I doubt it will throw a code, but it could.
The O2 sensor on the new header should simply adjust that bank for whatever flow changes you just made. Unless you reach a rich/lean limit you shouldn't get a code.
Put it this way... the manifolds on Ford Mod motors always cracks on the passenger side. It will get bad enough that it dilutes the exhaust to the point where it will trip a light for rich limit, but I doubt it will cause any issues. If one new header causes a CEL for bank 2 with just one, it would cause two CELs for both banks once you install the other one. Hence my prediction that it won't matter a hill of beans.
Curtis73 (Forum Supporter) said:
I think you'll be fine. I doubt it will throw a code, but it could.
The O2 sensor on the new header should simply adjust that bank for whatever flow changes you just made. Unless you reach a rich/lean limit you shouldn't get a code.
Put it this way... the manifolds on Ford Mod motors always cracks on the passenger side. It will get bad enough that it dilutes the exhaust to the point where it will trip a light for rich limit, but I doubt it will cause any issues. If one new header causes a CEL for bank 2 with just one, it would cause two CELs for both banks once you install the other one. Hence my prediction that it won't matter a hill of beans.
yeah, and I've already had a crack in the header that was replaced, so the 02 was likely already adjusting fuel trim on that bank. I'd be more concerned if these were long-tube headers with cat delete or something, but they're just shorties with similar diameter to stock.
irish44j (Forum Supporter) said:
Not sure I've ever heard of anyone putting a turbo on only one bank of a V-engine, but can't say I really pay attention to that stuff.
GM-era Saab thought it was a great idea!
I'll put in a vote for "it'll be fine."
In reply to obsolete :
interesting. Figures Saab did it. Bunch of weirdos that also put the clutch in front of the engine :)
irish44j (Forum Supporter) said:
Keith Tanner said:
We took a stock manifold from a Toyota 3.4 and welded a turbo flange on it with a T3. Left the other side stock. Ran that way for years and years - we may have put 100k on it before we sold it. Next owner drove it until it was wiped out by a drunk.
Just out of curiosity, what was the rationale for only doing one or not doing it downstream after the merge? Not sure I've ever heard of anyone putting a turbo on only one bank of a V-engine, but can't say I really pay attention to that stuff.
Done before my time at FM. I don't know what Bill's plan was, but it was probably the easiest packaging solution :)
If you think the turbo install was sketchy, you don't want to know about the fuel...
irish44j (Forum Supporter) said:
Keith Tanner said:
We took a stock manifold from a Toyota 3.4 and welded a turbo flange on it with a T3. Left the other side stock. Ran that way for years and years - we may have put 100k on it before we sold it. Next owner drove it until it was wiped out by a drunk.
Just out of curiosity, what was the rationale for only doing one or not doing it downstream after the merge? Not sure I've ever heard of anyone putting a turbo on only one bank of a V-engine, but can't say I really pay attention to that stuff.
Irish, not a production car engine but in 2001-2002 we used a "single sided turbo" setup on the Toyota Cart/Champ cars. They were not building a ton of boost due to regulations, but the sound was quite different (louder) than the Hondas and Fords(Cosworths) we ran against. Originally we only used the system on oval tracks but later used it for for road coarse as well. The thinking was since we we only running a few inches boost, the turbo could be driven from one side and the other left open for less restriction/losses. Boost tuning was more difficult, but we figured it out. Those engine spun to 17k+ with only 2.65L displacement.
