Welcome to the North American Subaru Impreza Owners Club Thursday November 20, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Built Motor Discussion

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 07-08-2008, 04:08 AM   #1
86ray86
Scooby Newbie
 
Member#: 172069
Join Date: Feb 2008
Default Brian crower 2.71 stroker kit ??

Hey Guys

im from australia and looking for some opinions from you guys that have used this kit and have pushed big hp with it. im looking to push 500-550kw atw with this kit, will the pro rods be able to cope. as there my main concern, any advice and feedback would be great...
* Registered users of the site do not see these ads.
86ray86 is offline   Reply With Quote
Old 07-08-2008, 11:35 AM   #2
WRX 2002
Scooby Specialist
 
Member#: 11211
Join Date: Oct 2001
Chapter/Region: MWSOC
Location: Gurnee IL
Vehicle:
2004 STi
Rally Blue

Default

1 KW is approx. 1.34 HP. So 670HP to 737HP. not bad expectations.
WRX 2002 is offline   Reply With Quote
Old 07-12-2008, 05:19 AM   #3
86ray86
Scooby Newbie
 
Member#: 172069
Join Date: Feb 2008
Default

anyone have any feedback on this kit, im looking at buying very soon as my 2.5 has been sold...
86ray86 is offline   Reply With Quote
Old 07-12-2008, 03:57 PM   #4
Sinister redlines
Scooby Specialist
 
Member#: 120641
Join Date: Jul 2006
Chapter/Region: NWIC
Location: Port Orchard, WA
Vehicle:
05 HTA3586,BB 2.5L
CGM

Default

I have one and its a great setup, just rather expensive to get fully going. The main reason is that not only is it a stroker setup but also a big bore. This requires the darton big sleeves for the 102mm bore. This alone adds about $1600 to the setup on top of the actual stroker kit.
Sinister redlines is offline   Reply With Quote
Old 07-12-2008, 04:04 PM   #5
novacivic
Scooby Specialist
 
Member#: 117980
Join Date: Jun 2006
Chapter/Region: NESIC
Location: Rochester, NH
Vehicle:
2005 sti
wr blue

Default

why not go with and axxis 2.65l stroker
novacivic is offline   Reply With Quote
Old 07-12-2008, 05:50 PM   #6
86ray86
Scooby Newbie
 
Member#: 172069
Join Date: Feb 2008
Default

why? reasons ?
86ray86 is offline   Reply With Quote
Old 07-12-2008, 06:04 PM   #7
86ray86
Scooby Newbie
 
Member#: 172069
Join Date: Feb 2008
Default

Quote:
Originally Posted by Sinister redlines View Post
I have one and its a great setup, just rather expensive to get fully going. The main reason is that not only is it a stroker setup but also a big bore. This requires the darton big sleeves for the 102mm bore. This alone adds about $1600 to the setup on top of the actual stroker kit.
what kind of power you putting through it ? did you use the rings that cam with the kit or sorce your own ?
86ray86 is offline   Reply With Quote
Old 07-12-2008, 11:06 PM   #8
SniperSVD
Scooby Newbie
 
Member#: 168633
Join Date: Jan 2008
Default

i think the problem with stroker kits this big is the piston speed. to me it seems that you are bound to break, i remember seeing titainium rods, cobb i believe,
SniperSVD is offline   Reply With Quote
Old 07-13-2008, 01:55 AM   #9
Sinister redlines
Scooby Specialist
 
Member#: 120641
Join Date: Jul 2006
Chapter/Region: NWIC
Location: Port Orchard, WA
Vehicle:
05 HTA3586,BB 2.5L
CGM

Default

Quote:
Originally Posted by SniperSVD View Post
i think the problem with stroker kits this big is the piston speed. to me it seems that you are bound to break, i remember seeing titainium rods, cobb i believe,

Stroker having piston speed issues? No, in fact they are actually slower. However the main debate is rod ratio not speed. Not to mention the amount of stroke increased is small compared to other applications (79mm - 83mm = 4mm = .157" roughly 5/32")

A small block chev is 3.480" stroke vs a 383 is 3.750" = .270" a little over 1/4" big difference....

Last edited by Sinister redlines; 07-13-2008 at 02:21 AM.
Sinister redlines is offline   Reply With Quote
Old 07-13-2008, 07:02 PM   #10
bcblues
Scooby Specialist
 
Member#: 17256
Join Date: Apr 2002
Chapter/Region: MWSOC
Location: America's Outback
Vehicle:
04 STi
Blue w/ custom bug splat

Default

Long rod kits would really help our subie boxers. Anybody make a long-rod kit? The short search I did came up wanting....
bcblues is offline   Reply With Quote
Old 07-14-2008, 02:09 AM   #11
Sinister redlines
Scooby Specialist
 
Member#: 120641
Join Date: Jul 2006
Chapter/Region: NWIC
Location: Port Orchard, WA
Vehicle:
05 HTA3586,BB 2.5L
CGM

Default

not in a stroker setup due to the assembly process on subies making the rods hang from the crank then after the case is together you install the piston and wrist pin. This makes the fact that the oil ring cannot cover the wristpin and theres no more room to push the pin higher on the skirt.
Sinister redlines is offline   Reply With Quote
Old 07-14-2008, 11:09 AM   #12
Homemade WRX
Scooby Guru
 
Member#: 33782
Join Date: Mar 2003
Chapter/Region: MAIC
Location: 3MI Racing LLC
Vehicle:
96 bastard child
search FIRST, then PM!!!

Default

Quote:
Originally Posted by bcblues View Post
Long rod kits would really help our subie boxers. Anybody make a long-rod kit? The short search I did came up wanting....
yup, someone does...
If I say more than that, I will definately get in trouble.
Homemade WRX is offline   Reply With Quote
Old 07-14-2008, 11:15 AM   #13
Homemade WRX
Scooby Guru
 
Member#: 33782
Join Date: Mar 2003
Chapter/Region: MAIC
Location: 3MI Racing LLC
Vehicle:
96 bastard child
search FIRST, then PM!!!

Default

Quote:
Originally Posted by Sinister redlines View Post
Stroker having piston speed issues? No, in fact they are actually slower. However the main debate is rod ratio not speed. Not to mention the amount of stroke increased is small compared to other applications (79mm - 83mm = 4mm = .157" roughly 5/32")

A small block chev is 3.480" stroke vs a 383 is 3.750" = .270" a little over 1/4" big difference....
a stroker motor at the same RPM as a long rod, will have higher instantaneous accelerations in a subaru because you have to shorten rod ratio to stroke. Might want to rework your "slider crank model" again.
My long rod setup is 1.8:1 and the 2.71 stroker is 1.57:1

You can also assemble the block quite easily with a long rod setup. There is also room to push the ring package up without much sacrifice to the ring lands...
I KNOW this for a fact. I spent a few years designing and modeling my package.

Last edited by Homemade WRX; 07-14-2008 at 12:52 PM.
Homemade WRX is offline   Reply With Quote
Old 07-14-2008, 11:43 AM   #14
MS WRX
Scooby Specialist
 
Member#: 117780
Join Date: Jun 2006
Chapter/Region: South East
Location: Jackson, MS
Vehicle:
2004 WRX
Aspen White

Default

Quote:
Originally Posted by Sinister redlines View Post
Stroker having piston speed issues? No, in fact they are actually slower. However the main debate is rod ratio not speed. Not to mention the amount of stroke increased is small compared to other applications (79mm - 83mm = 4mm = .157" roughly 5/32")

A small block chev is 3.480" stroke vs a 383 is 3.750" = .270" a little over 1/4" big difference....
Yes but MOST small block chevy engines dont rev to 8500rpm. The forces acting on the rod increases geometrically with rpm.
MS WRX is offline   Reply With Quote
Old 07-14-2008, 08:25 PM   #15
Sinister redlines
Scooby Specialist
 
Member#: 120641
Join Date: Jul 2006
Chapter/Region: NWIC
Location: Port Orchard, WA
Vehicle:
05 HTA3586,BB 2.5L
CGM

Default

Quote:
Originally Posted by MS WRX View Post
Yes but MOST small block chevy engines dont rev to 8500rpm. The forces acting on the rod increases geometrically with rpm.

Yes you are correct the forces do climb with rpm, and yes sb can rev to 8500 with lots of work. What you failed to see what I was saying is that the BC stroker doesnt gain all of its displacement from stroke but rather bore/stroke combination. My relation was just to show that there wasnt a huge change in stroke and that was all. So on....
Sinister redlines is offline   Reply With Quote
Old 07-14-2008, 08:32 PM   #16
Sinister redlines
Scooby Specialist
 
Member#: 120641
Join Date: Jul 2006
Chapter/Region: NWIC
Location: Port Orchard, WA
Vehicle:
05 HTA3586,BB 2.5L
CGM

Default

Quote:
Originally Posted by Homemade WRX View Post
a stroker motor at the same RPM as a long rod, will have higher instantaneous accelerations in a subaru because you have to shorten rod ratio to stroke. Might want to rework your "slider crank model" again.
My long rod setup is 1.8:1 and the 2.71 stroker is 1.57:1

You can also assemble the block quite easily with a long rod setup. There is also room to push the ring package up without much sacrifice to the ring lands...
I KNOW this for a fact. I spent a few years designing and modeling my package.

Maybe I showed what I was getting at incorrectly, but I was totally agreeing with the stroker not having the best rod ratio. And yes the blocks can be assembled the other way as I have had to disassemble one this way also. Its just not as easy with setting the rod bolts otherwise it is a other method and yes theres nothing wrong with the wrist pin in the ring lands (I have had different platforms like this in the past).

I have watched your build and you are playing with some neat ideas, but you are not the only one. I too have 12 years playing with built engines (that I have built not bought) so theres no reason to get defensive or agressive. I realize just about anything can be done but I was more getting at the norm as far as assembly and not the exotic. My next big build is going to be a short stroke, long rod, huge bore oddity.

Last edited by Sinister redlines; 07-14-2008 at 08:39 PM.
Sinister redlines is offline   Reply With Quote
Old 07-14-2008, 08:33 PM   #17
MartinSTi05
Scooby Specialist
 
Member#: 145145
Join Date: Apr 2007
Chapter/Region: MWSOC
Location: Rockford, Il
Vehicle:
2006 wrx STi

Default

In the end we are interested in forces applied to the various components in the system. A BC 2.71L stroker kit will yield higher forces than a standad 2.5L engine at any given RPM due primarily to three factors.
1. Extended stroke. A longer stroke means that the average piston speeds (and by definition average loading) will go up at any given RPM. 2. the extra stroke alters your rod stroke ratio, increasing the rate of acceleration the rod/piston see. 3. the 2.71L displacement is arrived at via an 83mm stroke and 102mm bore. Generally going from a 102mm piston from a 99.5mm piston will add some weight, further increasing rod/bearing etc loading at a given RPM.
Quote:
Originally Posted by Sinister redlines View Post
Yes you are correct the forces do climb with rpm, and yes sb can rev to 8500 with lots of work. What you failed to see what I was saying is that the BC stroker doesnt gain all of its displacement from stroke but rather bore/stroke combination. My relation was just to show that there wasnt a huge change in stroke and that was all. So on....
MartinSTi05 is offline   Reply With Quote
Old 07-14-2008, 09:34 PM   #18
Homemade WRX
Scooby Guru
 
Member#: 33782
Join Date: Mar 2003
Chapter/Region: MAIC
Location: 3MI Racing LLC
Vehicle:
96 bastard child
search FIRST, then PM!!!

Default

Quote:
Originally Posted by Sinister redlines View Post
I have watched your build and you are playing with some neat ideas, but you are not the only one. I too have 12 years playing with built engines (that I have built not bought) so theres no reason to get defensive or agressive. I realize just about anything can be done but I was more getting at the norm as far as assembly and not the exotic. My next big build is going to be a short stroke, long rod, huge bore oddity.
Sorry, I did not mean to come off as agressive but rather wanted to straigthen out the facts. Also, my wrist pin is not in my ring lands...I just chose my components wisely
same reason it is easy to assembly my long rod setup...others it would depend on how they did things.

Sounds like you are following in a similar path to mine
Homemade WRX is offline   Reply With Quote
Old 07-14-2008, 09:38 PM   #19
Homemade WRX
Scooby Guru
 
Member#: 33782
Join Date: Mar 2003
Chapter/Region: MAIC
Location: 3MI Racing LLC
Vehicle:
96 bastard child
search FIRST, then PM!!!

Default

Quote:
Originally Posted by MartinSTi05 View Post
3. the 2.71L displacement is arrived at via an 83mm stroke and 102mm bore. Generally going from a 102mm piston from a 99.5mm piston will add some weight, further increasing rod/bearing etc loading at a given RPM.
also might add increased friction and decreased ring life
Homemade WRX is offline   Reply With Quote
Old 07-14-2008, 10:18 PM   #20
Sinister redlines
Scooby Specialist
 
Member#: 120641
Join Date: Jul 2006
Chapter/Region: NWIC
Location: Port Orchard, WA
Vehicle:
05 HTA3586,BB 2.5L
CGM

Default

Quote:
Originally Posted by Homemade WRX View Post
Sorry, I did not mean to come off as agressive but rather wanted to straigthen out the facts. Also, my wrist pin is not in my ring lands...I just chose my components wisely
same reason it is easy to assembly my long rod setup...others it would depend on how they did things.

Sounds like you are following in a similar path to mine

Its all good, just wanted to be clear And I have been mistaken before and will be again for sure. LoL
Sinister redlines is offline   Reply With Quote
Old 07-15-2008, 11:55 AM   #21
MS WRX
Scooby Specialist
 
Member#: 117780
Join Date: Jun 2006
Chapter/Region: South East
Location: Jackson, MS
Vehicle:
2004 WRX
Aspen White

Default

Sinster, i was not flamin ya dude, just made that face to show what a chevy sbc would look like at 8500 LOL
MS WRX is offline   Reply With Quote
Old 07-15-2008, 11:04 PM   #22
MartinSTi05
Scooby Specialist
 
Member#: 145145
Join Date: Apr 2007
Chapter/Region: MWSOC
Location: Rockford, Il
Vehicle:
2006 wrx STi

Default

Another thing to consider regarding high RPM stroker operation.
Harmonics. Considering the fact that the 83mm Stroker crank uses oem bearing journals, by definition you have 1.5mm less overlap of the rod journal/main journal cross section as compared to a standard 79mm ej25/7 crank, and 4mm less overlap than an ej20/7 based setup. Material choices aside, this would make a crank that is less torsionally rigid. Losing rigidity generally accompanies a reduction in resonant frequency. Theoretically this would lower the RPM at which potentially damaging torsional vibrations can manifest themselves.
How much the above is really worth worrying about is still up in the air. I have a 2.71L crower kit now, and hope to get it running soon, i will let you guys know how it fares.

Last edited by MartinSTi05; 07-16-2008 at 08:33 AM. Reason: Homemade WRX caught a screwup;-)
MartinSTi05 is offline   Reply With Quote
Old 07-16-2008, 12:40 AM   #23
Homemade WRX
Scooby Guru
 
Member#: 33782
Join Date: Mar 2003
Chapter/Region: MAIC
Location: 3MI Racing LLC
Vehicle:
96 bastard child
search FIRST, then PM!!!

Default

also to add to the cons of the 2.7L is the clearancing of the block for the kit...so adding more loading on the block, increased harmonics and a weakened block...I'd say they start to run into issues at in the high-7k to low-8k rpm range

also you had a typo martin...the EJ25 is 79mm
Homemade WRX is offline   Reply With Quote
Old 07-16-2008, 08:07 AM   #24
MartinSTi05
Scooby Specialist
 
Member#: 145145
Join Date: Apr 2007
Chapter/Region: MWSOC
Location: Rockford, Il
Vehicle:
2006 wrx STi

Default

Quote:
Originally Posted by Homemade WRX View Post
also to add to the cons of the 2.7L is the clearancing of the block for the kit...so adding more loading on the block, increased harmonics and a weakened block...I'd say they start to run into issues at in the high-7k to low-8k rpm range

also you had a typo martin...the EJ25 is 79mm
Oops, my bad, your right, i was thinking ej20.
MartinSTi05 is offline   Reply With Quote
Old 08-25-2008, 03:18 AM   #25
PENGUIN_JF1BJ_EJ22T
Scooby Newbie
 
Member#: 187550
Join Date: Aug 2008
Default con rod clearance

Is anyone else having clearance issues when they are putting this motor together?
Last week I got back the block and started the rebuild, but when I finished connecting the first 2 pistons I found there was “knock” and an obvious metal on metal drag when I turned the engine over. Aver some careful inspecting and the help of a sharpie I found one of my con rods was hitting the block at BDC.
For this kind cash I thought it should be a no mod’in rebuild,
Going at a re-sleeved sti block with the dremel, That just seems wrong
PENGUIN_JF1BJ_EJ22T is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Brian Crower 83mm billet stroker crankshaft mikeesingh Engine/Power/Exhaust 1 05-31-2010 01:56 PM
injectors for a 2.71 stroker... help! greekmafia Built Motor Discussion 3 09-05-2008 11:32 PM
Brian Crower Cams, Springs, Stroker kits! WE GO THEM! RallySport Direct Engine/Power/Exhaust 1 07-10-2008 04:57 PM
Brian Crower 2.29L Stroker Kit : Subaru WRX EJ20 ElCuRaNdEr Built Motor Discussion 9 10-13-2007 11:12 AM
Brian Crower 2.29L Stroker Kit: Subaru WRX EJ20 ElCuRaNdEr Newbies & FAQs 3 07-24-2007 12:39 PM


All times are GMT -4. The time now is 06:08 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.