I don't see how this could be true. It seems to me that a good header would improve power AND fuel economy (reduce emissions).

 

This is entirely untrue. ULEVII has its greatest impact on evaporative emissions. Concessions for ULEVII are the onboard vacuum pump that detects and measures leaks, the charcoal filter on the intake in the airbox, and the CEL when you fail to sufficiently tighten the gas cap. Add to this the WB02 sensor in the exhaust manifold and the intentional rich cold cycle operation to get the cats up to temperature as quickly as possible, and you have just about everything significant for ULEVII. Tailpipe emissions standards haven't changed a lot in a long time because the manufacturers now have a hard time distinguishing between ambient air and engine exhaust - sometimes the exhaust is actually "cleaner" than the air going in the engine. And it has nothing to do with the log style manifold they gave us.

We got the OEM piece because it's easy to fit in the space allowed, and the engine made target power with these manifolds. Sure there's more to be had, but they didn't intentionally dumb down the engine - they let the accountants design the exhaust, not the engineers.

 

Well I certainly appreciate the info and lesson....

I was totally basing it on an opinion I had.. and was posting with out thinking in dept...

The stock manifold(s) design is restrictive yet performs well for the engine design & space..

Joe Z

 

I think there could be 20 - 30 hp in the exhaust manifold if done right. It would be the most significant power mod for the 2GR-FSE to date. The original design is horrid from a pure performance perspective. I'm also not terrifically impressed with the quality of the internal welds on the JUN-TW piece, but I'd bet it will still outperform the stock piece. Almost anything is better than the stock piece in this case.

 

So is it officially a no go on the Header project from LMS? Our only option is JUN-TW?


how about JoeZ puts together something special

 

mazzuri's should be out by year end and he has had some pretty good success with the is300 headers.

 

A few of the things I've noticed about the IS350 manifolds is servicability. I suppose one could build a flange with 1.5" ports sticking out and having the primaries of the header slip onto them and be held with springs like sport bikes and a lot of race cars use. This would make installation a little easier.

The right side seems a lot easier to work with. The left side seems most difficult since you have most of the accessories and the steering column's shaft to deal with.

IMO, if someone were to make headers for the IS350 it would be beneficial to move the cats downwards and make their tubes of a longer length for proper scavenge effect at high RPM. The cats can be located just after the current manifold flange and so the primary A/F sensors can be moved to the location of the secondary sensors are and the secondary sensors can be moved further down stream. The reason why we wouldn't want to place the cats where the current secondary cats are is the warmup of the cats is more than likely monitored for the ULEV II compliance. If the cats take too long the ECU may detect a problem with them. Do it more than once consecutively and the 2-trip detection fail would set off the MIL. Due to this the headers might even require heat wrapping to reduce the possibility of loosing the heat from them.

Since I also favor true dual exhaust I think a full manifold back system would net a substantial gain but it would have to use a convertor of some sort to keep the emissions monitoring of the ECU within its programmed allowable parameters.

-Joe

 

I hope so, Ive seen his piece for the IS300 and its very nice.

 

The problem with moving the cats is it'll fail any strict emissions inspection... aftermarket cats are only legal if they don't change the location.

This may or may not be an issue for some states (that either don't look close or don't care it's not technically legal), but it'd pretty much kill any chance of them being legal in california or ever getting a CARB number... (and ditto for any other states similarly strict).

 

FYI, my header will remove the 2 cats that are on the stock manifold now.

 

i'm happy that i live in florida and emmissions arent tested. i would rather have the Cats removed. please can we just get some good quality headers sooon lol

 

Well, removing the cats is illegal in all 50 states, it's just that in states w/out emissions you're a lot less likely to get caught... I do know one case where a state trooper still ticketed someone in a non-emissions state for it though, but there was enough clearance on the vehicle for the cop to have looked under and seen em not there...

I'm sure you'll still sell a fair number of headers without cats, just given the number of states that check, and how much a pain it'd be to swap stock parts on annually, I suspect you'd sell -a lot- more if you offered hi-flow cats that passed at least a visual.

 

99% of Cops won't even know that there are 4 CATs on the car, if they look under, they will still see 2 more.

 

Count me in if these go production mazzuri!

 

Probably true... but a lot closer to 100% of all inspection stations will know, which means nobody in states that do a visual (most states) can go without cats unless they want to swap their headers/exhaust at least once a year.