Headers

[Mojofilter]

So what is the current opinion on the Man A Fre full-up headers/exhaust system? Currently $1.5K, and gotta wait for them. I need to make a decision between headers and stock iron manifold soon. Complete desmog and AFI TBI system by the way.
Thanks!!

 

[OSS]

There are those that claim.... once you install headers, you’ll be chasing vacuum leaks/exhaust leaks forever

 

[TanTLC]

I've been running a set of Man A Fre headers going on 10 yrs (think i paid half as much back then) and I would highly recommend them. It is important to take the time to match the flange plate thickness of the headers to the intake manifold so when the bolts are torqued they apply even pressure, I think this is where most people struggle with getting them to seal well. I simply used a caliper to measure the width of each and then ground the flange on the headers (on the bolt side, not the gasket side) to match the corresponding thickness of the intake (on the pair i received the flange for the headers was thicker than the intake by a few thousandths typically). Never have i had an issue with them, I think there great.

 

[Seth S]

You might consider running a set of 3fe exhaust manifolds with a custom y downpipe. Probably give you a nice gain at less than a tenth of the cost.

 

[BurntToast]

I've been running a set of Man A Fre headers going on 10 yrs (think i paid half as much back then) and I would highly recommend them. It is important to take the time to match the flange plate thickness of the headers to the intake manifold so when the bolts are torqued they apply even pressure, I think this is where most people struggle with getting them to seal well. I simply used a caliper to measure the width of each and then ground the flange on the headers (on the bolt side, not the gasket side) to match the corresponding thickness of the intake (on the pair i received the flange for the headers was thicker than the intake by a few thousandths typically). Never have i had an issue with them, I think there great.

Can you expand on this? Torque shouldnt be effected by flange thickness. Hell even axial load applied through a torque wrench can be up to 20% variation with a click wrench

 

[cps432]

Can you expand on this? Torque shouldnt be effected by flange thickness. Hell even axial load applied through a torque wrench can be up to 20% variation with a click wrench

If you have two different thicknesses you will not be putting the same amount of force on the thinner side. If the flange for the intake is lesser than the flange on the exhaust the bolt will rest on the exhaust side leaving the intake side with a bad seal.

 

[1911]

So what is the current opinion on the Man A Fre full-up headers/exhaust system? Currently $1.5K, and gotta wait for them. I need to make a decision between headers and stock iron manifold soon. Complete desmog and AFI TBI system by the way.
Thanks!!

I've run headers on lots of engines over the years, though the only Toyota engine was a 3FE in an FJ80. For that, I did use MAF headers.

In my experience, almost all headers rust out over time, and I've had ceramic coated, chromed, etc. They also radiate tremendous extra heat into the engine bay, firewall, and even under your feet.

The MAF 3FE headers gave me a noticeable seat-of-pants acceleration and gas mileage boost - but the extra heat in the engine bay cooked the fuel injection wiring harness clips brittle, and they broke and let said wire's insulation touch and melt off. They also rusted out; pinhole leaks. Took them off and welded up the pinholes, and they rusted out more pinholes again. Over the course of 4 years or so. After that, I put the stock manifolds back on.

You might consider running a set of 3fe exhaust manifolds with a custom y downpipe. Probably give you a nice gain at less than a tenth of the cost.

This is what I'm going to for the 2F in my 40.

 

[TanTLC]

Can you expand on this? Torque shouldnt be effected by flange thickness. Hell even axial load applied through a torque wrench can be up to 20% variation with a click wrench

On the headers I received the width of the header’s plate steel flange was thicker than the casting of the intake manifold. There are bolts/washer that torque to both the header and the intake. Those flanges need to be the same width so the torque is evenly applied to the sealing surfaces. Failure to rectify that difference in thickness is often a reason for burning gaskets.

 

[TanTLC]

On the headers I received the width of the header’s plate steel flange was thicker than the casting of the intake manifold. There are bolts/washer that torque to both the header and the intake. Those flanges need to be the same width so the torque is evenly applied to the sealing surfaces. Failure to rectify that difference in thickness is often a reason for burning gaskets.

 

[britbike2001]

I recently gave up on the stock exhaust manifold due to the endless leaks at the joints and put in a JT Enterprises header. The first one they sent me was off a bit and impacted the intake manifold. They replaced (promptly) it and the second one was tight but did not touch the intake manifold.

To deal with the different thicknesses, I rounded up a bunch of stainless steel washers, of slightly different thicknesses, cut them in half and test fit for each bolting location. This has solved all of my exhaust leak issues.

Before installation I coated the headers with high temp exhaust paint. Initially smells bad but that goes away. We'll see how long they hold up but I'm happy with the results so far.