Log in
Search
Latest topics
» How's the weather?by rsv1cox Today at 10:32 am
» Wen Mac .049 - Conditioning.
by MauricioB Today at 9:54 am
» Jim Walker Firebaby
by rsv1cox Today at 8:27 am
» Enya .09 II Questions
by sosam117 Today at 8:24 am
» music vids.. some of your favorites
by crankbndr Today at 8:03 am
» Draco Goes Flying, But Misses the Eclipse
by HalfaDave Yesterday at 9:59 pm
» A prototype Cox Reed-valve marine engine
by davidll1984 Yesterday at 9:15 pm
» Happy 53rd birthday Mauricio!!!
by MauricioB Yesterday at 11:47 am
» Testers Sprite engine swap
by Greenman38633 Yesterday at 10:57 am
» UV Restore of Yellowed Decals
by Levent Suberk Yesterday at 8:59 am
» 22mm 2-blade nylon marine prop and solid-shaft drive
by roddie Yesterday at 6:46 am
» Post edit??
by roddie Yesterday at 5:33 am
Cox Engine of The Month
Comparison between old and new SPI method?
Page 1 of 1
Comparison between old and new SPI method?
Has anyone compared RPM and power output between the old style SPI(low positioned open port/standard piston) and a new style SPI(higher positioned port/shortened lighter piston)? The lighter rotating assembly might develop higher RPM, but at the cost of torque. Any opinions? And what about removing the slit?
Bernie answered this in this other thread: http://coxengineforum.forumakers.com/t142-cox-international-wish-list#1648
The answer is.................................. Yes, the new SPI combo will out-scream a #1 BW cylinder.
So in the words of Rosanne Rosannadana... Nevermind!
Bernie answered this in this other thread: http://coxengineforum.forumakers.com/t142-cox-international-wish-list#1648
The answer is.................................. Yes, the new SPI combo will out-scream a #1 BW cylinder.
So in the words of Rosanne Rosannadana... Nevermind!
_________________
Don't Panic!
...and never Ever think about how good you are at something...
while you're doing it!
My Hot Rock & Blues Playlist
...and never Ever think about how good you are at something...
while you're doing it!
My Hot Rock & Blues Playlist
RknRusty- Rest In Peace
- Posts : 10869
Join date : 2011-08-10
Age : 68
Location : South Carolina, USA
Re: Comparison between old and new SPI method?
According to my information, the "bypass booster port" porting style on the later slit exhaust cylinders had proved to be better than the original single groove dual bypass cylinders.
The original dual bypass cylinders had one big groove in each side. In an attempt to find more power on Non SPI (muffled or throttled) engines with slit exhaust ports, the slit exhaust cylinders added a single boost port to each bypass, which because of the way it extends slightly above the main bypass helps create a swirling effect of the atomised fuel into the cylinder during the intake stroke as well as providing a larger intake port.
This was discovered by Larry Renger and he attempted to enhance and improve this even further when he built this feature into the Venom cylinder. I believe some of these cylinders were also used in late model ie post 1997 Tee Dees. This would have also been a bonus in manufacturing time and cost as it removed a couple of steps in the milling process of the cylinders as the Tee Dee previously had two bypass boosters in each bypass and they discovered one was actually more efficient than two!
So it doesnt surprise me that by lightening the piston even further and adding sub piston induction would increase performance even further. After all, all high performance cox engines had sub piston induction in the past, so it must have been there for a reason. ie it worked!
The original dual bypass cylinders had one big groove in each side. In an attempt to find more power on Non SPI (muffled or throttled) engines with slit exhaust ports, the slit exhaust cylinders added a single boost port to each bypass, which because of the way it extends slightly above the main bypass helps create a swirling effect of the atomised fuel into the cylinder during the intake stroke as well as providing a larger intake port.
This was discovered by Larry Renger and he attempted to enhance and improve this even further when he built this feature into the Venom cylinder. I believe some of these cylinders were also used in late model ie post 1997 Tee Dees. This would have also been a bonus in manufacturing time and cost as it removed a couple of steps in the milling process of the cylinders as the Tee Dee previously had two bypass boosters in each bypass and they discovered one was actually more efficient than two!
So it doesnt surprise me that by lightening the piston even further and adding sub piston induction would increase performance even further. After all, all high performance cox engines had sub piston induction in the past, so it must have been there for a reason. ie it worked!
Re: Comparison between old and new SPI method?
Interesting to note the difference between the old and new SPI's. Several of my older Coxes must have been retro-fitted with multi-slitted cylinders and the shorter pistons my Golden Bee NOT among them.
BTW, scored ZERO Coxes at the HUGE swap meet that I attended over Labor Day weekend. None were even presented which I thought unusual.
SuperDave
BTW, scored ZERO Coxes at the HUGE swap meet that I attended over Labor Day weekend. None were even presented which I thought unusual.
SuperDave
SuperDave- Rest In Peace
- Posts : 3552
Join date : 2011-08-13
Location : Washington (state)
Similar topics
» Older Brothers
» Power Comparison
» Stuck .020 TD
» digital scale comparison
» Engine comparison chart
» Power Comparison
» Stuck .020 TD
» digital scale comparison
» Engine comparison chart
Page 1 of 1
Permissions in this forum:
You cannot reply to topics in this forum