RB25 (250) - Pictures & Spec....

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tha83
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Fri Jan 16, 2009 5:53 pm

Dan, I must agree that your photos are excellent. Great job on the write up. The only thing lacking would be a list of upgrades and a cost analysis. good work! thanks for the link from the BBS to here. The guys on the LCUSA would like it as well.

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RinB
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Fri Jan 16, 2009 11:00 pm

Nice Photo's Dan :D You beat me to it !! "Bast@rd" I got hold of the one Im playing with tonight :lol:

We've now got the port maps so we can get time area's, and port timings which is brill, and I will fill in a few more details.....

Well with reference to the RB22, I’ve been playing a lot with them as shown on here, and it looks like AF have put right a few things on the RB25 which I don’t think a lot of people will know about.

First one, which I have mentioned a few times, they have now made the secondary transfer ports symmetrical ;) They're sat about 80deg. The primary trans are sat the same as before at around the 55 deg mark.

Right the second update, is when you look down at the barrel with exhaust at top and the inlet bottom, the left side of the piston gudgeon pin cut out is narrower than the right side on the RB25 piston....which is good! On the RB22 piston, basically the asso type, the gudgeon pin cut outs are the same width. n each side.

So what am I going on about you ask?!!!!

Well the RB22 piston on the left side passes the transfer gas straight out the secondary exhaust port, because of the left side cutout being to wide around the piston.

see pics below.....

The piston area i'm talking about seen on the RB25 on left RB22 on right

Image

See the two black lines on RB piston this is the area of cut out see how it overlaps transfer and exhaust port

Image

And here on the RB25 the black line sits nicely between trans & exh

Image

Right something to watch out for....the RB25 piston crown is flatter then the Asso RB22 crown, so if you use a standard 225 head and think....Ill open it out for a 250........don't forget the crown and squish profile!

The RB25 piston does not have the bridge cooling holes drilled into the piston to help cool the exhaust bridges? I would have thought this would have been done as they are doing them on the RB22.

Right lets talk now the Vertical angles of the transfers and Boost.

Well as Dan discribed the third finger is acting like a tranfer and its Va is sat the same as the transfers at about 0-2 deg.

Which I think could be better @ a Va of 15deg with the horizontal angles of the main sat around the 55deg.

The Boost Va is at 50 deg which is reasonable but may do better being a bit more.

How ever these ports are alot better then the RB22 ports, and hey I dont have access to the flow equipment airseal have! :( As always it is a fine line to get new gas in to cool the piston head with out loosing it out the exhaust.

The great thing about these barrels is that AF have given us more great toys to play with. :twisted: with a lot of potential. 8-)

Smiffy
If its made of Metal Fettle it !!

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saigonmark
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Wed Feb 25, 2009 4:26 am

Rayspeed's advert for the RB25 says that this kit will fit on a machined 200 casing; what exactly needs to be done here? I'd like to get one and bring it over here but I need this info first.

Cheers

Mark

AndyS
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Wed Feb 25, 2009 12:57 pm

Mark the casing is machined out to accept the larger spigot on the barrell. I took mine in and they did it while I waited, took about 20 mins. Best to warn them before you go though.

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drunkmunkey6969
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Wed Feb 25, 2009 1:03 pm

AndyS wrote:Mark the casing is machined out to accept the larger spigot on the barrell. I took mine in and they did it while I waited, took about 20 mins. Best to warn them before you go though.
Don't think he'll be visiting AF Rayspeed from Vietnam!! :lol: :lol: :lol:

;)

Lamaddict
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Thu Feb 26, 2009 2:21 am

Hats off to Ray and Ben. Literally leaving other tunning shops in their wake :)

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saigonmark
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Thu Feb 26, 2009 4:05 am

AndyS wrote:Mark the casing is machined out to accept the larger spigot on the barrell. I took mine in and they did it while I waited, took about 20 mins. Best to warn them before you go though.
Maybe the RB20 will be enough for me then so no need to buy new casings...I was just dreaming..as you do :mrgreen:
drunkmunkey6969 wrote:
AndyS wrote:Mark the casing is machined out to accept the larger spigot on the barrell. I took mine in and they did it while I waited, took about 20 mins. Best to warn them before you go though.
Don't think he'll be visiting AF Rayspeed from Vietnam!! :lol: :lol: :lol:

;)
I'll be home in April so look out for me at Scarborough....I'll be wearing that world famous tee shirt ...under a thick woolly jumper and two coats as it currently 30 degrees C over here :!:

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