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There has been a lot of people who have had the manifold crack/leak but from those pictures its actually a crack or snap off of the flange section of the header from the tubes. I noticed that one of my flanges on my driver side header was loose from the tubes. My tubes and flanges were still in perfect condition with no signs or cracks when I swapped them out for PPE headers. I decided to compared it to my friend's OEM headers and noticed that it was the same on his.
I found it may be somewhat a weird design as i noticed the top flanges on the driver side header has both holes with gaps and are not welded to the tubes (therefore they're loose from the tubes) (picture #1-4). The holes that do NOT have gaps can be seen to be welded to the tubes. All other flanges (other 3) are connected to the tube because they have at least one hole (without gap) that is welded. From the passenger header (picture #6) you can see that the end tubes holes (top hole and very bottom hole) with no gap are welded to the tubes. The two center tubes holes with gaps are not welded and if i put force on it, they separate (has play) from the tubes. The flanges on passenger header however will not fully separate from tubes because end tube holes (top and bottom holes) are welded so they wont be falling off.
I believe this is normal? My guess is that it was designed like this for some maneuverability during install?
Don't show me those pictures. It makes me want to get aftermarket headers!!!
The horror of the oem header--and yours actually don't look THAT bad comparatively. Although, I guess we should thank Lexus for making this "thing" since you can tell just by looking at it there will be significant gains to be had in the aftermarket.
I believe this is normal? My guess is that it was designed like this for some maneuverability during install?
Yeah i was expecting my 2008 flange to be cracked off too but it wasn't. The installer told me that was the reason why those were detached was for easier installation
Yeah I believe its normal for the top flange to be loose on the driver side top tubes because it's not welded. As long as u don't have cracks in tube
Mine came like that too, no cracks that everyone is talking about...
Not sure why but the headers are the biggest design flaw and a must have for any Isf owner. If I had to do it all over again, headers would always be first mod on this car, again the biggest design flaw in terms of design for this car imo.
Our stock headers are the saddest design on a performance vehicle I have seen in some time lol. Can you imagine how much more factory power the ISF would have been rated at if they had designed a proper header like the E92 M3?
So would that mean the rattle sound is only the flange being loose and needs to be tightened?
no, the flange will clamp the pipes down when it's torqued down. The sound is exhaust gas escaping through a cracked pipe. I imagine as more cars go out of warranty, people will repair their cracked headers by welding. The 100-Series Landcruisers/LX470s have the same issue.
Mine came like that too, no cracks that everyone is talking about...
Not sure why but the headers are the biggest design flaw and a must have for any Isf owner. If I had to do it all over again, headers would always be first mod on this car, again the biggest design flaw in terms of design for this car imo.
Originally Posted by FFM
Our stock headers are the saddest design on a performance vehicle I have seen in some time lol. Can you imagine how much more factory power the ISF would have been rated at if they had designed a proper header like the E92 M3?
yeah I agree with you guys when I saw how the header design was on my old E92 vs the ISF I was like wow no wonder there was so much still left on the table. Cause on the E92 headers are dumb expensive and gain no power but the stock header is a tubular manifold as is, so its hard to design better than that.
But on the ISF I was like yeah they could've done a little better, but then again looking at the RCF stock manifold I guess they did(which doesn't help us at all but still)
yeah I agree with you guys when I saw how the header design was on my old E92 vs the ISF I was like wow no wonder there was so much still left on the table. Cause on the E92 headers are dumb expensive and gain no power but the stock header is a tubular manifold as is, so its hard to design better than that.
Originally Posted by FFM
Our stock headers are the saddest design on a performance vehicle I have seen in some time lol. Can you imagine how much more factory power the ISF would have been rated at if they had designed a proper header like the E92 M3?
Highlighted both statements for truth!
Exactly my sentiment when I saw the factory tubular design of the E9x series M3 and the lengths that they went through to make a proper equal length header for that car
Then you see the log style manifold on the ISF and it dawns on you why you gain so much power from just a header swap on our vehicle!
Normal for OEM header?
