4 INTO 1 EXHAUST SYSTEMS

[AWI]

My company now manufactures these systems for many RV's. We took over these products from Aircraft Exhaust Technologies. I am looking for results in performance from builders who converted from the original system to the 4 INTO 1. If you have any info in changes in static RPMs, climb performance, EGT temps, engine sound, etc, I would like to hear from you.
Our web site is being updated to include 4 INTO 1 info, should be up by next Monday.
[email=jhole@awi-ami.com]

[robbieattaway]

When I built my RV6 I installed a 4 into 1 exhaust. I used that exhaust for about 90 hours. I could not shorten it so it extened past the cowl outlet pretty far. I changed to a 4 pipe system and picked up 4 MPH. ECI has done test on different exhaust and found the 4 pipe system puts out more horse power.

[rv969wf]

My -6 had a Vetterman crossover for about 300 hours. I later built my own 4 into 1 exhaust and it is an equal length 36" primary tubes. The noise level did go up. Fuel burn at full power went up about .5gph average. My new system has 165 hours or so of flying time. I did make and change collectors of various sizes and length to get the sound the way I liked it. After making the final collector, noise level has dropped 2 db. Does it make more power??? I think so but I do not have a dyno so I can't say the gain. At 65-75% cruise I could see no difference in speed. At full throttle down low I did see a slight gain in speed. My thoughts are the 4 into 1 is a better design for making maximum power for takeoff and climb. In level cruise flight or high alltitude I don't think it makes a diffference what style or design you have for an exhaust. Just my thoughts. Good luck with the new company.

[13brv3]

Originally Posted by rv969wf

My thoughts are the 4 into 1 is a better design for making maximum power for takeoff and climb. In level cruise flight or high alltitude I don't think it makes a diffference what you have for an exhaust. Just my thoughts.

Maybe not JUST your thoughts It's almost exactly what Aerosport told me when I asked them about 4in1 systems.

Cheers,
Rusty

[gmcjetpilot]

Originally Posted by 13brv3

Maybe not JUST your thoughts It's almost exactly what Aerosport told me when I asked them about 4in1 systems. Cheers, Rusty

I appreciate Alan's opinion but I do think the four into one work better at all power settings. There was extensive research done by the Cafe foundation on this. If you really want to learn more. Other wise I do agree at higher power it makes more difference. Any "Pipes" are good at only ONE RPM and power. So depending on the length and diameter of the primaries and secondary (the little and the big tubes before/after the collector) can tune the pipes for different RPM ranges. So if you want pipes that are more tuned for %55-75% power you can have that. Overall the cross over it OK but the 4in1 is higher performance. The down side is how it fits in the engine compartment or does not fit. If you have a RV "A-model" than forget it. Actually I have seen power flow style systems (commercial 4in1 sys) on a RV. It was home made with mild steel. It was complicated but fit. The pipes went forward to the collector mounted typically where the two pipes cross over, on a cross over system. With some 180 degree bends it was stuffed under the cowl. I have a carb and Vans airbox. I had AET make a custom set up with my pattern, came out nice. As Alan said putting around 4 into 1 is fine and gives you room for carb and fits A-models better.

[AWI]

Thank you to everyone who wrote replies in this Thread.

Regarding the CAFE foundation, AWI is a sponsor and you will find us named in that study in a paragraph on Pages 9 and 10.

We look forward to more replies on this subject.