Lil Toni adapter
12-15-2004, 03:06 AM
#1
Lil Toni adapter
I saw that Dub had made an angled adapter to use a Jett-stream muffler for a Jett90 on a GP Lil Toni. would Dub also do one to fit a Webra 120(I'm assuming Dub makes a Jett-stream for the Webra 120)? As aside, what kind of performance would a Webra 120 have with a Jett-stream? I was thinking of using something like an APC 13.5X12.5, or 14X12 prop.
12-15-2004, 11:13 AM
#2
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RE: Lil Toni adapter
Hi Dave........
Let me check on some background with the Webra 120 before I attempt to quote any specific performance info. I do know the webra responds quite well to the jett-stream muffler.
The Jett-Stream 120 muffler is tuned for the 9000-13,000 rpm band. Optimally, you want to prop the engine to run between about 10K and 11K rpm on the ground for best performance (speed application). The muffler will typically boost performance of a 120 size engine by 500-700 rpm above where it runs with a stock muffler (which is pretty substantial HP increase when dealing with a 15-16" prop).
The muffler extension slightly increases the tuning length. Drops the tune point about 300-500 rpm.....but it really shifts the torque curve, which means you can run slightly more pitch or larger diameter.
For reference, the big-block Jett SJ-120 with this muffler turns a 15x8 up just about 11k rpm, and a 16x8 around 9500 rpm.
A simple formula we like to use for compairing prop load on an engine:
dia x dia x dia x pitch = Constant
Compairing props in this way, a 16x8 results in C=32768 A 14x12 results in C=32928 which indicates a little higher load.
So, just off hand, if you can get the Webra/Jett-stream/muffler extension combo to turn a 14x12 (or the 13x12) up just over 9000 rpm peak, on the ground, you will do quite well. It will easily unload up near 10K in the air, and will take off.
Let me double check on the adapter. If I recall, the webra 120 is a bolt-on muffler in the first place (bolts to the case, rather than through the case). It requires the standar adapter to convert it to bolt-through, then would need a bit more of an extension.
Also keep in mind the 120 muffler is a bit longer than the 90 muffler... I'm not sure how that plays into the installation.
Bob
Let me check on some background with the Webra 120 before I attempt to quote any specific performance info. I do know the webra responds quite well to the jett-stream muffler.
The Jett-Stream 120 muffler is tuned for the 9000-13,000 rpm band. Optimally, you want to prop the engine to run between about 10K and 11K rpm on the ground for best performance (speed application). The muffler will typically boost performance of a 120 size engine by 500-700 rpm above where it runs with a stock muffler (which is pretty substantial HP increase when dealing with a 15-16" prop).
The muffler extension slightly increases the tuning length. Drops the tune point about 300-500 rpm.....but it really shifts the torque curve, which means you can run slightly more pitch or larger diameter.
For reference, the big-block Jett SJ-120 with this muffler turns a 15x8 up just about 11k rpm, and a 16x8 around 9500 rpm.
A simple formula we like to use for compairing prop load on an engine:
dia x dia x dia x pitch = Constant
Compairing props in this way, a 16x8 results in C=32768 A 14x12 results in C=32928 which indicates a little higher load.
So, just off hand, if you can get the Webra/Jett-stream/muffler extension combo to turn a 14x12 (or the 13x12) up just over 9000 rpm peak, on the ground, you will do quite well. It will easily unload up near 10K in the air, and will take off.
Let me double check on the adapter. If I recall, the webra 120 is a bolt-on muffler in the first place (bolts to the case, rather than through the case). It requires the standar adapter to convert it to bolt-through, then would need a bit more of an extension.
Also keep in mind the 120 muffler is a bit longer than the 90 muffler... I'm not sure how that plays into the installation.
Bob
12-15-2004, 01:37 PM
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RE: Lil Toni adapter
follow up to earlier post....
Dub can make the extensions to go along with the adapeter. You would have to specify the application and engine when ordering them muffler. Extension assembly should run about $25, but you would want to confirm that.
In speaking with two webra 120 owners, concensus is that a 14x10 might be more what you are looking for in this application.
I trust this is helpful
Bob
Dub can make the extensions to go along with the adapeter. You would have to specify the application and engine when ordering them muffler. Extension assembly should run about $25, but you would want to confirm that.
In speaking with two webra 120 owners, concensus is that a 14x10 might be more what you are looking for in this application.
I trust this is helpful
Bob
12-17-2004, 10:13 AM
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RE: Lil Toni adapter
Definately. The G90 responds nicely to the jettstream. Its a real good engine. Prop selection may take a little work, but ask around in the extream speed forum. A few guys using the G90 on some warbirds for racing and stuff. Id probably suggest starting with a 12x6 and letting the engine turn up a bit.
Infact, the muffler bolt pattern and spacing on the ST90 are identical to the SJ-90L, so what you end up with is exactly the same muffler and extensions shown in the Toni pictures.
Bob
Infact, the muffler bolt pattern and spacing on the ST90 are identical to the SJ-90L, so what you end up with is exactly the same muffler and extensions shown in the Toni pictures.
Bob
