clearance issues- Powerflow exhaust and LoPresti cowl

[Hockeybabe39]

purchased my 1979 M20J last November- previous owners completed a lot of mods!

 

So, it appears that the PowerFlow exhaust is not happy with the LoPresti cowl- anyone else with this combo having clearance issues?  The scat tube has rubbed a hole in the middle of the lower cowl, and the #1 header tube has been rubbing against the cowl flap hinge.  We just changed the engine mounts per PowerFlow- so, the header tube is barely clear now, but the scat tube isn't clear.  Neither PowerFlow nor LoPresti seems to be bothered by the clearance issues.

 

So, I may have a use PowerFlow exhaust available, as I'm planning on yanking it if we can't solve these issues.

 

thoughts?

 

thanks

 

Alicia

[N601RX]

I think I remember reading something on powerflows web site that only a certain generation of the muffler would work with the lopresti. Don't remember if it was gen 1 or 2.

[KSMooniac]

I thought the PF wasn't compatible with the LoPresti cowl at all.  STC'd products aren't necessarily guaranteed to be compatible with each other, and it is supposed to be up to the installing IA mechanic to determine this.  I suspect you'll have to go back to the standard exhaust...

[Hockeybabe39]

the exhaust was modified when the cowl was installed.  There is a LoPresti-cowl specific PowerFlow exhaust- gen 1 only.

 

Per the installation instructions for the exhaust.

[testwest]

and we have this combo flying, see the picture! We did get the special PF mod for the Lopresti cowl. IIRC, the difference is in the #2 header. Check with Powerflow, they should be able to help. Have all of the STC paperwork in hand when you call.

[Hockeybabe39]

thanks- I'm going to bug them at OSH.  My mechanic has been sending them pictures for the last 3 weeks and they keep saying that there isn't an issue.  A huge hole in the cowl, and a cowl flap about to fall off seems to be an issue to me!

[Bennett]

I have both the LoPresti cowl and the Power Flow exhaust system. LASAR does all my maintenance work and annuals, and aside from some general mentioning of "tightness" in space, there have been no problems with this setup. There is some annual maintenance on the PoweFlow system that by memory seems to add about $500 to every annual. At least I know that it is well maintained.