Update on my project!
27 November 2003, 01:55 PM
#121
Correct me if i am wrong, but seeing as the max load on the conrod is a function of acceleration (+ve and -ve) combined with a comparativly small amount of load from cylinder pressure, then wouldn't high revs be putting on very high bearing loads also.
You might also be interested in this paper:
http://www.surrealmirage.com/subaru/files/SAE_boxer.pdf
It has some very interesting info that I haven't seen before, paticularly about the bearings.
Paul
You might also be interested in this paper:
http://www.surrealmirage.com/subaru/files/SAE_boxer.pdf
It has some very interesting info that I haven't seen before, paticularly about the bearings.
Paul
27 November 2003, 02:13 PM
#122
Subaru Tuning Specialist
Join Date: Jun 2002
Location: 7.74 @179 mph 1/4 mile - road legal
Posts: 6,654
Likes: 0
Received 1 Like
on
1 Post
Agree Paul, it is a combination of revs and torque. The load on the bearing to produce 500lb-ft torque is an average of 500*304.8/39.5 = 3858lbs. This is an average force over 180 degrees rotation, most of which has a smaller lever arm than the 39.5mm of a 2.5 engine. I'd estimate IRO 10,000 lbs peak loading from combustion alone. To produce decent power, you need to hold on to the torque up the rpm range, I had done the sums for piston/rod acceleration force but forget them.
Andy
Andy
27 November 2003, 02:47 PM
#123
Scooby Regular
Join Date: Aug 1999
Posts: 7,957
Likes: 0
Received 0 Likes
on
0 Posts
bit confused.
paul, which bit are you referring to in that pdf?
Also, there is mention that the increased stiffness of the crank due to its large overlap between main and big end journals reduces friction more than the required increased big end diameter increases friction.
This makes sense except that I would appreciate someone being able to explain why a stiffer crank will decrease friction, and if so, friction between which components? Could there finally be an advantage to me having spent stupid money on a billet crank?
paul, which bit are you referring to in that pdf?
Also, there is mention that the increased stiffness of the crank due to its large overlap between main and big end journals reduces friction more than the required increased big end diameter increases friction.
This makes sense except that I would appreciate someone being able to explain why a stiffer crank will decrease friction, and if so, friction between which components? Could there finally be an advantage to me having spent stupid money on a billet crank?
28 November 2003, 08:31 PM
#124
Scooby Regular
iTrader: (1)
Join Date: Jan 1999
Location: UK
Posts: 15,271
Likes: 0
Received 0 Likes
on
0 Posts
Glad to see you have all been having fun since I was away!
Anyway, back on topic a few comments.
The final build of my engine was carried out by Dave Wild at DTW. This was a much to mitigate the forever lengthening waiting time and to allow SMG to focus on fixing Johns engine.
For the record the configuration of my short engine is identical to JBs and it runs very quietly and has done right from the off.
Regarding comparitive RR runs, there will be a small issue here as I suspect that running my car in 4th will overspeed the rollers as I have very long gearing. It will of course run in third, however this will give some (not a great deal) of difference in results. If anything, slightly short gearing can give better results, however roller grip will be an increased issue with the torque figures.
Finally, which will give up first, my gearbox or my bearings. Not really sure - the main thing is that on road it is very unlikely I will be utilising all that torque - however on the rollers, quarter etc we will have to wait and see.
However, unlike some munters, I will be out there and I will be happy to give it a go
Rannoch
PS If ANYONE would like to discuss issues not relating to my project such as other peoples engines then please start your own thread. Thank you
Anyway, back on topic a few comments.
The final build of my engine was carried out by Dave Wild at DTW. This was a much to mitigate the forever lengthening waiting time and to allow SMG to focus on fixing Johns engine.
For the record the configuration of my short engine is identical to JBs and it runs very quietly and has done right from the off.
Regarding comparitive RR runs, there will be a small issue here as I suspect that running my car in 4th will overspeed the rollers as I have very long gearing. It will of course run in third, however this will give some (not a great deal) of difference in results. If anything, slightly short gearing can give better results, however roller grip will be an increased issue with the torque figures.
Finally, which will give up first, my gearbox or my bearings. Not really sure - the main thing is that on road it is very unlikely I will be utilising all that torque - however on the rollers, quarter etc we will have to wait and see.
However, unlike some munters, I will be out there and I will be happy to give it a go
Rannoch
PS If ANYONE would like to discuss issues not relating to my project such as other peoples engines then please start your own thread. Thank you
28 November 2003, 09:16 PM
#125
Subaru Tuning Specialist
Join Date: Jun 2002
Location: 7.74 @179 mph 1/4 mile - road legal
Posts: 6,654
Likes: 0
Received 1 Like
on
1 Post
PS If ANYONE would like to discuss issues not relating to my project such as other peoples engines then please start your own thread. Thank you
Can't I even say that I had a run in John Banks's 2.5 car last night and it was very impressive for 1 bar boost 
Pulling well from 2500rpm with virtually immediate response 
It's going to be a very nice set up once the boost is raised a bit and the map sharpened up. I must try and get a run in it at Crail dragstrip just to keep the 1/4 mile title in Scotland a 'wee while' longer Andy
01 December 2003, 11:50 PM
#129
Scooby Regular
Join Date: Nov 2001
Location: Leeds - It was 562.4bhp@28psi on Optimax, How much closer to 600 with race fuel and a bigger turbo?
Posts: 15,239
Likes: 0
Received 1 Like
on
1 Post
I went out in Davids car with him tonight.. and OMG, the noise is something else..
David
David
03 December 2003, 02:16 PM
#138
Scooby Regular
Join Date: Nov 2001
Location: Leeds - It was 562.4bhp@28psi on Optimax, How much closer to 600 with race fuel and a bigger turbo?
Posts: 15,239
Likes: 0
Received 1 Like
on
1 Post
<snatches wooden spoon and kicks andy>
<crunchie.. - friday feeling >
<crunchie.. - friday feeling
>
04 December 2003, 12:02 AM
#141
Subaru Tuning Specialist
Join Date: Jun 2002
Location: 7.74 @179 mph 1/4 mile - road legal
Posts: 6,654
Likes: 0
Received 1 Like
on
1 Post
T-uk you may be interested in this snippet from Rannochs website, posted almost one year ago !
Just as well he didn't say which year
Andy
(that spoon's mine wallis)
an engine rebuild is now underway.
All will be revealed early in the New Year!
scoobyonthemoor
24/12/02
All will be revealed early in the New Year!
scoobyonthemoor
24/12/02
Andy
(that spoon's mine wallis
)
04 December 2003, 05:03 PM
#142
Scooby Regular
Join Date: Mar 2001
Location: uk
Posts: 1,998
Likes: 0
Received 0 Likes
on
0 Posts
Rannoch
Scooby Regular
Posts: 1440
From: one car to another and back again!
Registered: 21-01-1999
[ADD TO MY VIP LIST]
posted Saturday, November 22, 2003 12:35
--------------------------------------------------------------------------------
Quick update - engine finished and off to be put back into car
so which engine will we get to read about
hands spoon back to wallis , since it's the only action in this thread
Scooby Regular
Posts: 1440
From: one car to another and back again!
Registered: 21-01-1999
[ADD TO MY VIP LIST]
posted Saturday, November 22, 2003 12:35
--------------------------------------------------------------------------------
Quick update - engine finished and off to be put back into car
so which engine will we get to read about
hands spoon back to wallis , since it's the only action in this thread
09 December 2003, 05:49 PM
#148
Scooby Regular
Join Date: Mar 2001
Location: uk
Posts: 1,998
Likes: 0
Received 0 Likes
on
0 Posts
may-be grown into a 2.36
paul, why the late edit?
you and DW hinted that the engine was a goer , which is what the threads originator wanted
[Edited by T-uk - 12/9/2003 5:51:27 PM]
paul, why the late edit?
you and DW hinted that the engine was a goer , which is what the threads originator wanted [Edited by T-uk - 12/9/2003 5:51:27 PM]
