HomeTechnical ReviewsTurbo Headers, No Exhaust, No Boost, No Go

Turbo Headers, No Exhaust, No Boost, No Go

Turbo Headers, No Exhaust, No Boost, No Go

This year, while tuning my bike on Livengood’s dyno I had the typical reservations I always do whenever I hear my motorcycle screaming in a small enclosed room. It just does not seem right to have a motorcycle hitting 11K rpms spitting out 244hp at 6lbs boost while stationary.

We had just tuned the 6lb boost and had moved to the 10lb. range. Brian had set the A/F at 11.8:1 and the bike was at 288hp when he let off the throttle after the run was complete. As the bike was winding down it started back firing every once in awhile, something it has not done before. Brian made another pull and the HP dropped to 279. The popping was worse than the first time with a couple of fireballs coming out the exhaust about 2 ft in diameter. Brian got off the bike and said, “Check the header for a leak. It is sucking air somewhere.”

I grabbed a flashlight and went searching. I checked the header bolts first as I have had them come loose before. They were all in place. I looked at the header where it had been re-welded by Ken at Velocity Turbo the year before to touch up some hairline cracks it had. They looked good.

I asked Brian to make one more pull so I could watch the header and see if there were any flames coming out where they should not be.





As Brian was making the pull and reached about 8,000 rpms the problem became readily apparent; mainly because the turbo fell off the bike at the header flange right in front of my eyes. As soon as Brian heard the sound change he chopped the throttle and hit the dyno brake, looking at me with a face that says, “WTF.” I told Brian I found the problem, due to my finely honed keen sense of the obvious.

Turbo Headers

In the case of motorcycle turbos, the headers have a large responsibility. Not only are they tasked with making sure all of the exhaust gases spin the impeller, they also have to hold the weight of the turbo. For the most part a majority of the turbo manufacturers for motorcycles use stainless steel to make their headers. With all of the vibration a motorcycle experiences, not to mention the occasional wheel stand and resulting slam landing, this puts a lot of stress on the stainless steel which is not known for its flexibility.

All you have to do is do a quick search for “turbo header crack” on Hayabusa.org and you will come across many threads concerning the hairline cracks found in turbo headers after a few years of hard drag racing use. Many offer suggestions as to where to make and attach brackets to help hold some of the turbo’s weight and give the headers a break.

In my instance I noticed the hairline cracks early last year when I took the motor down. At the time Velocity Turbo was still owned by Barry Henson. I sent it in and Ken had the cracks TIG welded.

New owner of Velocity Turbo

Velocity Turbo was sold to Jason King of RPM Cycle Performance whom I spoke with when I called this year to see if I could get a new turbo header. Jason informed me the headers formerly made by Velocity prior to his taking it over were made of 304 stainless. He now makes them 321 stainless in an effort to give them more strength.

RPM TIG welds the headers by running argon gas through the inside of the headers which allows the weld to take place on the inside and the outside at the same time. This is one of the advantages of TIG welding I am told. RPM also increased the weld area around the flange where mine broke.

They offer the new improved replacement headers to any Velocity Turbo set up prior to his taking over the company for $800.00.

Going forward

I am curious as to how the new header will hold up. It feels heavier than my old one and looks much stronger in the weld areas. But in racing anything can happen, all you can do is build the strongest components possible and hope for the best. As racers we are constantly pushing parts to their extremes on a regular basis. It is good to know there are manufacturers out there willing to extend those extremes by creating new designs so we can push the boundaries further.

Paul Cavanaugh

In this instance I am just glad I found the extreme of this component on the dyno and not on the strip…

See ya at the track!

 

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