Long Tube Header Dyno results & Photo

[richardholdener]

We are doing testignon the ball/socket joint to see if there is enough flex for motor rotation, but if not there will have to be a flex joint. It looks like stainless constructionis important to some so we will investigate pricing for stainless.

Originally Posted by rob323

Richard, is there any provision to allow for the twisting of the motor? Flex joints etc?

[richardholdener]

Multiport fuel injection means there is one fuel injector per cylinder usually located in the head or intake port aimed directly at the back of the intake valve. The sequential or batch fire refers to whether the individual injector is fired or the enitire bank is fire for each cylinder. Sequential is prefered and is usually the choice at lower engine speeds where emissions are lowered, but many sequential systems revert to bacth at higher engine speeds. Regardelss, if you lose an injector in a multiport injection system, the individual cylinder will suffer-which will be registered by the oxygen sensor (usually located in the joined collector of exhaust manifold). Losing an injector can literally ruin a cylinder from detonation. The yaris has individual injectors for each cylinder-they do not spray in any other cylinder. Hope this clears things up.

Originally Posted by WolfWings

Not how it works. Only diesel engines and direct-injection engines have individual fuel injectors 'in' each cylinder. Most have multiple injectors to equalize the air/fuel ratio across the cylinders, but even if you have a single fuel injector fail it should cause a global drop in overall fuel available, with a minor to major additional localized drop on the closest cylinders to the fuel injector that failed. The global drop should still be picked up regardless of which exhaust runner the sensor is in.

And then there's cars that only have SPFI (one injector for the whole engine) instead of MPFI, and even among MPFI there's sequential (one spurt per cylinder timed with the intake stroke to fine-tune the air/fuel ratio beyond just flattening it across all cylinders, what all super-modern engines like our Yaris use, admitedly maximized local effect from a single failed injector), simultaneous (timed spurts from all injectors at the same time, pure air/fuel levelling across all cylinders, least impact from a failed injector), and batched/hybrid that fires injectors more often than needed (more than once per stroke), but vaguely synced with the intake cycle, usually I've seen that only on engines that also have a waste-spark ignition system or V engines to simplify the ECU logic and use a wiring harness that just Y-forks to each bank for the injectors instead of running individual control circuits for each injector.

[jkuchta]

Thanks a lot for looking into the stainless option for us Richard.


Also, ...about that split header flange.....


How are you bolting this thing onto the cylinder head? Are you not using the center bolt (i.e. only using 4 header bolts)?

[WolfWings]

Originally Posted by richardholdener

We are doing testignon the ball/socket joint to see if there is enough flex for motor rotation, but if not there will have to be a flex joint. It looks like stainless constructionis important to some so we will investigate pricing for stainless.

What the other guy said, thanks for looking into the stainless pricing, Richard! If it turns out overly prohibitive, mild will do, but thanks again for checking on the stainless for us.

[richardholdener]

The prototype header employed a split flange to facilitate installation, but production pieces will have a single flange like the stock ex man. The header will be two piece, but the connection will come down on the primary tubing. The header has to be a 2-piece design to allow for installation. On the prototype, we did use the center bolt but with a washer to secure both halves-it worked great.

Originally Posted by jkuchta

Thanks a lot for looking into the stainless option for us Richard.


Also, ...about that split header flange.....


How are you bolting this thing onto the cylinder head? Are you not using the center bolt (i.e. only using 4 header bolts)?

[gboezio]

Originally Posted by jkuchta

Gboezio and WolfWings....you're both about half right.

Stainless and Mild steel both have high melting points, but Stainless conducts heat far less than mild steel, making it much better for exhaust applications. Also, stainless is much less susptable to scaleing and errosion than mild steel, making it even more superior in this application.
As far as embrittlement...while it will happen, the reduced fatigue strength of 304 will still be higher than that of mild steel, making for a stronger header.

My bad, I did not specify coated mild steel. I would not run an uncoated steel header.
Maybe 304 would work fine on non turbo application, someone's got to try