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Thread: Looper exhaust porting
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08-04-2014, 01:17 AM #376
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10-21-2015, 05:21 AM #377
Time to wake this thread up again...
My 2.7 looper (describen in this thread) has been used successfully for another summer!
New mods this summer was increased compression by cutting the heads(1mm) alongside with the head shave, I had the airbox gutted and carbs rejetted.
By midsummer, I tossed the VRO, and went Holley Blue, which gave me a couple of hundreds up top(clearly a bit sarving before at WOT...)
My motor runs fine, but according to the compression readings, I think its time to renew the cylinder bores beyond honing and rings... Compression right now is 105-107 on all six.
My intention is to get the cylinders bored to 3.685 in order to get the primary and secondary compression up and in the same time continue the hunt for 300hp's
About pistons; I got a fairly good deal on 1993-2000, fingerport looper pistons from Vertex, are they any good? Can I use them in my application?
When I cut my fingerports, I placed them "in the middle", between the main transfers and the boost port, will their location match the f/p holes in the above pistons?
About porting;
I want to make my f/p's a bit deeper before boring the sleeves, how deep can I go, measured from the stock 2.7 sleeve?
//Anders
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10-21-2015, 08:36 AM #378
The last stock 2.7 I had compression was around 115. We run 140 with no issues on 93 I think your going to need to up compression to get near 300.
Match the piston ports to the fingers make them as wide and flow in the same direction.
Do do you plan on removing the bridge in the exhaust port?
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10-21-2015, 08:47 AM #379
If I was to keep the current bore size and further increase the compression by shaving the heads even more, where is the limit? I have already shaved 1mm(0.039")
Since I am not planning to turn more than appx 6500rpms, do I have anything to gain by removing the exhaust bridge?
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10-26-2015, 02:53 AM #380
Started porting today!
Decided to use the other 2.7 block I have in the garage, a really fresh one which has never seen salt water.
I started by adding the fingerports in order to reduce the risk of messing the fresh bore up.
I am trying to cut the fingers a bit deeper and and a bit higher to better fit the increased boresize.
Right now I am trying to figure out weather to widen the exhaust windows (appx .150 at the top, taper down to stock)or to leave them?
I dont plan to turn the motor much passed 6500, I want huge torque in low-midrange, so I can turn bigger wheels.
I have read Racers article on how to reach 300hp's, but perhaps thats out of reach if you don't want to turn higher rpms?
At last I found a shop to bore my cylinders! The shop want the pistons in advance in order to maintain the proper piston to cylinder clearance, now I must find the right pistons for my application.
Can any of you guys point me in the right direction when it comes to pistons?
I want the 3liter pistons with fingerport holes in the skirts, and the ring stops located in the fingerport area. What are these called/numbered?
//Anders
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10-26-2015, 04:00 AM #381Screaming And Flying!
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Dont give your boring guy a piston he has no idea of the piston to bore clearance.
You just tell him what size hole to finish.
Dont cut the finger ports till you have the pistons to ensure the pin is in middle ish of the finger.Last edited by powerabout; 10-26-2015 at 04:39 AM.
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10-26-2015, 05:54 AM #3825000 RPM
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I will check my wiseco pistons when i get home. I thought they had the ring locator pins in the fingers.
Where is the article Racer wrote about achieving 300hp?1975 Hydrostream Ventura II
1987 evinrude 200xp
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10-26-2015, 09:34 AM #383
Attachment 330468Took the old jig out...
30 min later...
After 1hr, first cyl ready
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10-26-2015, 11:23 AM #384
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10-26-2015, 01:05 PM #385"12" Super Lite Tunnel (11') "88" 25 Yammy twin carb "BANANA SPLIT"
"77" Hydrostream Viper "87" 140 Rude heavy modded w/15" mid, Bobs nose and lwp "DANGER ZONE"
"72" Checkmate MX-13 "80" 75 Rude w/15"mid and Nitro Lu (to be restored)
"Too much is never enough" Keith Richards " Dreams become reality via hard work and perseverance" G.A.Carbonneau
"This coming from an old man that strapped two bananas together, hung a motor on it and calls it a boat" XstreamVking
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10-26-2015, 04:57 PM #386I'd rather be competitive w/junk I built in my garage than win w/stuff I bought.
I refuse to allow common sense to interfere w/my boat buying decisions.
Checkmate 16' 140 Johnson
Hydrostream 17' Vector FrankenRude I
Laser 480 (?) 21' w/GT 200
Glastron Carlson Conquest w/XP 2.6
Glastron Carlson CVX 20 w/XP 2.6
24' Sonic w/twin 250 Johnsons
24' Sonic w/twin 250 HO Johnsons
19' STV River Rocket w/FrankenRude II
Allison XR 2002 w/Frankenrude II
Hydrostream 18' V-King w/Frankenrude II
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10-26-2015, 05:21 PM #387
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10-26-2015, 06:28 PM #388
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10-26-2015, 07:19 PM #389"12" Super Lite Tunnel (11') "88" 25 Yammy twin carb "BANANA SPLIT"
"77" Hydrostream Viper "87" 140 Rude heavy modded w/15" mid, Bobs nose and lwp "DANGER ZONE"
"72" Checkmate MX-13 "80" 75 Rude w/15"mid and Nitro Lu (to be restored)
"Too much is never enough" Keith Richards " Dreams become reality via hard work and perseverance" G.A.Carbonneau
"This coming from an old man that strapped two bananas together, hung a motor on it and calls it a boat" XstreamVking
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10-27-2015, 03:46 AM #390