stock headers diameter

[Assyrian]

hi everyone....

does anyone know what the diameter of the stock header pipe is as it attatches to the cat?

thanks.

[DatSRBoi]

Good luck with finding the answer. I doutb anyone here really knows. We dont get much supports on headers and all so no one really messes with it.

Are you thinking about custom?

[Assyrian]

nope... I'm thinking about a hi flow cat... and I'm trying to research parts but I'll need the stock headers diameter.

oh well lol

[DaveMush]

I did measurements when I used a 2001 1mz-fe from a Solara in my Mr2 a year and a half ago.

Manifold pipes are each 1", downpipes are 1.5" each, the pipe after the y is 2 1/8", the inlet for the stock cat is 2 1/8" and the exit from the car is 2 1/4" as a two bolt flange w/ gasket.

Room for alot of improvement.

[PhreakdOut]

I did measurements when I used a 2001 1mz-fe from a Solara in my Mr2 a year and a half ago.

Manifold pipes are each 1", downpipes are 1.5" each, the pipe after the y is 2 1/8", the inlet for the stock cat is 2 1/8" and the exit from the car is 2 1/4" as a two bolt flange w/ gasket.

Room for alot of improvement.

I believe Toyota uses 42.7mm (1.68") tubing on the front pipes and 54mm (2.13") tubing after the Y-Joint.

The smaller diameter on the header side helps with bottom end power. If you go S/C or turbo, then I recommend you increase the runners to 38.1mm (1.5") , 48.6mm on the downpipes and 60.3mm or 65mm after the Y-joint.

I may have a set of 1MZ manifolds at work. I'll check the pole barn on Tuesday.

EDIT: One other note: When checking pipe diameters: Many times, Toyota will require Airgap pipes. This is where there is and inner pipe and a larger diameter pipe over the inner. A layer of air between the two pipes insulates heat. (Either for faster converter light off performance or protect the engine bay from heat.) An outside measurement on an airgap pipes would be drasticly overstated.

[SleeperSolara]

I did measurements when I used a 2001 1mz-fe from a Solara in my Mr2 a year and a half ago.

Manifold pipes are each 1", downpipes are 1.5" each, the pipe after the y is 2 1/8", the inlet for the stock cat is 2 1/8" and the exit from the car is 2 1/4" as a two bolt flange w/ gasket.

Room for alot of improvement.

Man you have MR2 wit 1MZFE.

Good job on hte diameter explainantion.
Same wit you "PhreakdOut".

[Assyrian]

awesome explanation! thanks for all of the help!

[DaveMush]

One other note: When checking pipe diameters: Many times, Toyota will require Airgap pipes. This is where there is and inner pipe and a larger diameter pipe over the inner. A layer of air between the two pipes insulates heat. (Either for faster converter light off performance or protect the engine bay from heat.) An outside measurement on an airgap pipes would be drasticly overstated.

On my first 1mz-fe engine (from a 2001 manual Solara) the manifolds had simple pressed steel heat shields.
On my newest engine (2001 engine from an automatic Solara) the manifolds are exactly as you described. But the inner diameter of the pipes are the same as on my earlier manual manifolds.

Any of you guys need help with your engine wiring, ECU, or figuring out what the systems are... Let me know. I've had practice.
This time around, I'm rewiring the engine harness to be that of a manual set-up. Really its only a couple changes on the grounding of the ECU & a few sensors, a few nix-ed connections, and the swapping of the A/F sensors with heated O2 sensors. no resistors or tricks needed to get it going.

All of you who have Automatic trannys or have a cali-legal (not Fed-legal) engine, and are talking about o2 sensors... your using the wrong term. Your engines are equipped w/ Air/Fuel sensors.

[Assyrian]

thank you everyone for your help and avice... very encouraging.