G3i Ignition

G3i Ignition

Well Known Member
Dyno pulls are up on the Vetterman Exhaust Systems, The original standard 1-3/4? primary pipes and 2.0? tail pipe crossover exhaust system and also the NEW 1-1/2? primary pipes and 1-3/4? tail pipe crossover exhaust system. To view, go to http://www.g3ignition.com and select Dyno Runs from the menu.
ALSO Larry & Clint have more reading details @ http://www.vettermanexhaust.com/

See you in KOSH
Parked over @ IAC head quarters. Come by chat on engine performance, ignitions, induction, headers, dyno pulls, etc. Like to meet you.
A link on contact info:
http://www.g3ignition.com/images/AirVenture-2013.jpg
 
Interesting!

Being engine interested but knowledge constrained I was surprised to see
the smaller diameter pipes produced higher power at lower RPM and peaked at 2600
rpm at 167.82 hp then dropped off to 167.43 at 2700 rpm and 165.7 at 2800 rpm.
With the larger diameter exhaust pipes the horsepower was less at lower rpm all
the way up to 2700 rpm followed by a performance curve crossover beyond that
point until at 2800 the the larger pipe curve was still in a shallow climb and
showed a small 2.37 horsepower advantage.

I believe I have the standard larger pipe configuration. Several things are of
interest to me in this graph. Initially I misread the graph and thought my exhaust system was the blue line but Brian Carroll pointed out to me in the SARL YAHOO Group site that the standard (what I have) is the red line but the general conclusion is the same First - there is no way I would go to the larger
pipe configuration based on what I see. On the other hand since I have the larger pipe configuration there is no reason to change. [deleted incorect assumption]

What comments do you engine guys have on this.

Bob Axsom
 
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Smaller pipes have greater velocity for a given volume of gas.

Greater velocity gives better scavenging-----up to the point where the gas volume overloads the small pipe ability to move enough gas.

Same thing works for intake systems, low to mid RPM gives better cylinder filling due to velocity.

Lots more to it, but that is the "in-a-nutshell" version.
 
Could we have some torque figures also? I imagine with the smaller pipes there would bo an increase in torque!

We had the larger pipes fitted to our 0-235 and upgraded to the smaller pipes when they were released for the LSA 0-233. By these figures on the 0-360, it lookes like Larry could go even smaller ( 1 3/8" or even1 1/4" primary's perhaps??) for the 0-233 LSA.

It doesn't matter if you loose one or two knots off your top speed but some increase in power for take off and climb out would be hand with these small engines!

Bob
 
Just goes to show

RetiredRacer said:
It doesn't matter if you loose one or two knots off your top speed but some increase in power for take off and climb out would be hand with these small engines!

Bob
Click to expand...

Just goes to show the difference in perspective of different users - It might surprise one how many races are lost by less than two knots.

RV Blue class results two weeks ago in Townsend, Montana:

Race 411 Jeff Barnes RV-6 RV Blue 190.49
Race TF Brent Travis RV-4 RV Blue 189.91
Race 71 Bob Axsom RV-6A RV Blue 187.89
Race 155 Brian Carroll RV-7 RV Blue 183.92

Bob Axsom
 
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Any chance of seeing the same tests on a IO-320? I have the Vetterman 1.5" tubing cross-over with dual exhaust.

Just curious if any data exists between the 1.5 and 1.75 tubing on that engine.
 
Great post. Data is good. Any chance you'll do some pulls on the Vetterman 4 pipe system? That would be the trifecta of exhaust comparisons on the same engine.

Bets on the system I bought? :)
 
bobmarkert said:
Great post. Data is good. Any chance you'll do some pulls on the Vetterman 4 pipe system? That would be the trifecta of exhaust comparisons on the same engine.

Bets on the system I bought? :)
Click to expand...

Bob,
Talked with Larry this morning about doing some more pulls when we get back from KOSH, one of them being the 4-pipe system.
 
When I ordered the system for my O-360. Larry offered me the 1.5" system. I was a little nervous since that wasn't the norm. I asked larry which one he would use. He said he was running the 1.5" system on his rv. That was good enough for me. I have a muffler system, so my performance may differ. I went with that system to make up for some of the weight added by the mufflers.
 
Hey bob i just bought 1.5 with muffs for the 360 rv7, i gotta go back through your rotec notes soon and try.and source the right actuator arms!!! Speed shop right? Any advantage of sourceing them from a US shop? Or are there plenty of good suppliers in OZ?

Im gonna run Larrys 1.5 with muffs, Toms G3i s2 and Pauls Rotec on the 360 and see if i cant make em all play nice!.

Anyone else out there got that combo? With either a rotec or ellison TBI That can comment?
 
1.5 with muffs, G3i S2, Rotec TBI O-360 any chance of doing some pulls on that!?

RetiredRacer said:
Could we have some torque figures also? I imagine with the smaller pipes there would bo an increase in torque!

We had the larger pipes fitted to our 0-235 and upgraded to the smaller pipes when they were released for the LSA 0-233. By these figures on the 0-360, it lookes like Larry could go even smaller ( 1 3/8" or even1 1/4" primary's perhaps??) for the 0-233 LSA.

It doesn't matter if you loose one or two knots off your top speed but some increase in power for take off and climb out would be hand with these small engines!

Bob
Click to expand...

Hey retiredracer - Bob i just bought 1.5 with muffs for the 360 rv7, i gotta go back through your rotec notes soon and try.and source the right actuator arms!!! Speed shop right? Any advantage of sourceing them from a US shop? Or are there plenty of good suppliers in OZ?

Im gonna run Larrys 1.5 with muffs, Toms G3i s2 and Pauls Rotec on the 360 and see if i cant make em all play nice!.:cool:

Anyone else out there got that or similar combo? With either a rotec or ellison TBI That can comment?
 
Rob, The bellcrank in my Rotec TBI mounting photo's can be sourced from any shop that sells Sprintcar raceparts. It is a throttle bellcrank for a dirt track sprintcar! There are shops around Sydney that sell them. If you have trouble getting onto a supplier, get back onto me.

Bob
 
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