jgscott

iTrader: (1)

Here is another set of headers that I don't think many are aware of. I like these headers by design. They are shorties to but have a much better merge and collector.
Problem is I have never been able to confirm that they will clear the SC400 in the engine bay and side wall. They do fit and match up on the 1uZFE though.

JBrady

None of the designs are optimal so it becomes a question of function, price and practicality.

Do not worry about pairing the wrong ports on either the "Tex" style or S&S. What is most desirable is keeping internal collector volume to a minimum. This is something even the stock manifolds do and the result is surprising performance from such a horrible looking design.

The 4-1 Castle Hill shorties shown above do not fit the Lexus cars and even if they did I do not like the collector or pipe diameter.

The EK Tuning parts are nice looking, fit but will not accomodate cats in the stock locations and has a questionable collector and pipe sizing.

The S&S is like all designs in that they are of course a compromise but for the application a pretty good one. Aftermarket cats could be installed in the stock location if desired. I recommend installing the EGR flange in the exhaust after the header itself.

People tend to look at the exhaust cycle as an on/off switch which requires maximum flow. This thinking creates many of the misconceptions about exhaust such as bigger is better. The SMALLEST pipe size that will support the power required will give the BEST power/torque curve and make the most usable street engine (enjoyable) and that really is the goal, right?

The biggest neglected and or misunderstood dynamic is reverse flow and pressure. Big tubes and collectors make reverse flow easier both from a pathway standpoint and due to slower gas speed which changes direction easier. Small aerodynamic tubes have high gas speed, support surprising power and flow from the engines high pressure exhaust but are less friendly to reverse flow from the relatively low exhaust backpressure environment and are less likely for one pipe to pressurize another at the wrong time. Herein lies much of the reason why lousy stock parts make such good low RPM torque.

JohnEd

iTrader: (1)

JG,

When I went to Rush's site and looked at the TEX headers I thought they looked wierd for some reason. They had cylinders 1 and 3, and 5 and 7 paired together. I remembered the proper pairing as 1 and 7, and 3 and 5. With our firing order, 18436572, their pairing has the firing of 1 and 3 seperated by the firing of 8 and 4. Then the firing of 5 and 7 are in sequence. Timing is everything in a tri Y config and the timing in this header is a jumble. Actually these guys are going to act like 4 into 1's more than tri Y's. They actually look to be well made. though and the price is right. Tex might correct it's eror if enough interest was made in their product. Reconfigured, it would be a good performing street header if a cam were to accompany it.

For the purpose of blunting a law suit: This is only my humble opinion and not a scientific fact.

Now go to headerdesign.com and read the "scientific fact" that supports my conclusion. Everybody NEEDS to read the info at that site. GOLD!

Hope this helps

John

jgscott

iTrader: (1)

I am a bit confused. The header pics I posted above are not the Tex/Rush headers. I did not comment on those.

PS One of the most important things in Header is their ability to Scavenge and draw Exhaust gas exiting from the cylinders.

FYI - Each application is advantageous to the particular direction you are going with your motor. In my case
I will be running a Zex Nitrious application again as my previous 97 SC4 had. I did have and installed the S & S headers as many who comment have not, and experienced the before and after feel. I have no complaints about that Header at all, and my Butt Dyno felt a improvement in low to upper mid range power in Normal mode. With Forced induction changes, and now a different motor, the VVTI version of the 1UZFE my desires are a little different. A 125 shot of Nitrous should have no problem exiting much larger combustion explosion thru a larger exhaust headers and will surely like a larger exiting path.

Also concerning the low to midrange power, it is a proven fact, the the ability of the Unichip to adjust A/F, advance and retard timming that I will tune with. can add, 30-40 ft lbs of TQ in the midrange. This tunning tool will allow access to and the ability to adjust and optimize both the ignition and fuel system. UNICHIP has 17 RPM sites between 500 RPM and 8000 RPM and 13 load sites between zero throttle position and wide-open throttle position. This equates to 221 possible adjustments for fuel and a further 221 adjustments for ignition timing. I have the newest Unichip Q Ver. with also has down loadable real time Data recording capability. Along with the fact that a often over looked if even know fact is, that the VVTI motor has different head exhaust ports, larger Valves, and different cam lobes and lift.

My experience with the S & S Headers was great and as JBrady has stated the advantage of driveabilty and Mid TQ is most desirable on the mostly stock 1UZFE with the S & S headers.

JohnEd

iTrader: (1)

JG,

Great info on the VVTi heads. I was lusting after installing them on my 93 block and was advised that it wouldn't work. Is it true that the 93 engine is mechanically more rugged than the later version? Another thing you mentioned is that the valves have greater lift. How much? A cam grinder friend said that .3 was about all the lift you need with a four valve head. He said .35 was about the max he would recommend. Didn't quite sound right when I heard that. They interfere with the lift at .3, which seems unreasonable, so I guess increasing that would not complicate your life with extra belt changes.

Can you give more information on the Unichip?

Thanks

John

jgscott

iTrader: (1)

Here you go: http://www.dynoperformance.com/artic...?article_id=10

verylost

Even without being reconfigured, they are a good performing street header. There is a dyno out there to prove the gains.