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To make this post sensible, I am organizing into several sections, Overview/history, Block/Internal info, Head/Cam info, and finally, some additional reading that is related to the RN engine.
Overview and history
Over the last couple weeks, I have been scouring the internet for everything I can find on the Revision N whiteblocks, or RN for short. A quick background for those who aren't familiar with RN, when Volvo originally introduced the modular whiteblock engines, they were also known as the "N series".
Over the years, Volvo made lots of incremental changes, adding then removing EGR and SAS, changing the Motronic version, switching timing belt tensioners, going to a dual mass flywheel, along with a few other things. However, the basic internals of the engine stayed the same until around the turn of the millennium
In 1999, the first of the RN engines made their appearance. According to this PR piece from Volvo, which I believe to be from '99, states that "They are now also available in the naturally-aspirated engines in the Volvo S40, Volvo V40, Volvo S70, Volvo V70 and Volvo C70 Coupe and, within the space of the next one to two years, these engines will also be introduced in most of the turbocharged models." From this, arises some confusion. The '99 and up T5 engines have VVT on the exhaust, which implies that they are RN engines, but some differences, such as modified coolant paths in the cylinder head don't arrive until '00. Simply put, my understanding on when the the different engine models changed to the RN series is unclear, but I do know that by 2001, all 5 and 6 cylinder engines are the Revised version.Engine Block and Interals
Now we can get down to the nitty gritty stuff that I wish there was better documentation on, but the people who know the answers tend to keep it to themselves
On the inside, there were a lot of changes. RN engines got longer rods in 2002, with a few exceptions, increasing the length from 139.5 mm to 147mm. The engines that went into the S60R and V70R got thicker rods that are 143mm long. To match the change in rod length, the pistons got a shorter compression height and shorter skirts. To balance the change in reciprocating weight, they also got a lighter crank and smaller gudgeon pins for less weight and friction, for a total weight savings of 3.5-4.5kg (7.7-10lbs). The increased rod length improves the atrocious rod/stroke ratio, helping the engine develop a bit more torque, and allowing it to rev a little higher before destroying the pistons. Combined with the shorter skirts, the friction is reduced.
To improve windage in the crankcase, windows were added (See images in post #19).
All RN blocks have oil squirters to help cool the pistons, not just turbos.
There have been rumors of issues with harmonics at high power levels due to the lighter crank, although I cannot find good evidence or reports of this, and it may only apply to the 2.5L blocks. Take with a grain of salt until I can confirm or deny this
According to Jan at Wurthrline, the turbo engines got new (stronger) rods and pistons in 2002, which seems redundant, given the changes that were just made a few years prior. My suspicion is that it is similar to what happened in the late model redblocks, when the rod size changed from 9mm to 13mm, but the length of the hardware remained the same.
It is unclear if the '01-04 engines use the same rods as the '05+ engines. The stroke increases from 90 to 93.2mm when going from the B5234T3 to the B5254T3, bore changes from 81mm to 83mm. Both connecting rods are 143mm in length, center to center. For reference, the rods from the 05+ B5254T3 weigh 644 grams each
Cylinder Head and Cams
Possibly the most important changes were made to the head. In the late '99 time frame, Volvo started changing the heads over from hydraulic to solid valve lifters. The heads with solid lifters have approximately 20% larger intake ports, modified coolant and oil passages, and should bolt up to the previous revision blocks. The base circle on the cam increased 2mm. In addition the valve stem diameter changed from 7mm to 6mm. Intake and exhaust valves remained constant at 31mm and 27mm diameters, respectively.
Over the years, VVT was introduced in varying configurations. For single VVT setups, turbos got VVT on the exhaust, N/A got VVT on the intake. A rough breakdown for the turbo 5cyls:
1999-2000
99 2.3 T5 Single VVT 99 2.4 LPT Single VVT 00 2.4 R Single VVT
2001-2004
2001-2004 2.3 T5 Single VVT 2001-2004 2.4 LPT Single VVT 2005-2009 2.4 T5 Dual VVT 2003-2009 2.5 LPT Dual VVT 2004-2009 2.5 R Dual VVT
Other things besides VVT also changed:
Valve length and lift from Hydro to Solid lifter heads If anyone has duration numbers, I'd love to complete this chart!!
Intake Exhaust Length Lift Duration Length Lift Duration -98 B5244 N/A 8.45 250 8.45 252.6 (Note: some '93, and maybe '94, N/A engines got more aggressive cams) 1999 B5244 N/A 104.05 8.65 103.30 8.80 2001 B5244 N/A 104.25 8.65 103.30 8.80 -99 B5234T3 104.05 7.95 242 103.30 7.95 243.5 2001 B5234T3 104.25 8.40 103.30 9.05 2001 B5244T3 104.25 8.45 103.30 9.05
There have been anecdotal reports of the solid lifter heads flowing much better than the hydraulic lifter heads, even after the older heads have been modified:
ajhehr, on 11 January 2010 - 09:27 PM, said:
the later solid lifter head flows more stock then my hydraulic lifter head with full gasket match and port and polish.
If you use a head with VVT with an ECU that doesn't normally control the VVT, Lucky posted up a great tip on how to drive the VVT solenoid. If you don't drive the solenoid, be sure to block off the solenoid port, or the VVT will adjust itself
He also posted some info on using the new style head on an older engine. 
Ipd - Lucky, on 11 January 2010 - 06:20 PM, said:
Here's what I can add.
Latest version R head gasket is MLS (multi layer steel) like a Cometic, this is the stock replacement. I got mine from Victor Reinz.
The cooling ports are different, they are staggered and will provide better cooling. Oil feed and crankcase drain ports are all compatible. If you use a non CVVT head with the MLS gasket you'll have to drill a few ports into the cooling passages in the head to get adequate cooling.
So this means a CVVT head will bolt onto a non CVVT block.
You cannot to my knowledge put a non CVVT cam in place of a cam that was CVVT.
The journals are significantly different, this is true for any potentional non CVVT cam be it earlier 870 style or later P2 style.
Obviously modification could be made to the head but it's not a drop in.
You can run a CVVT system on a car that didn't come equipped with it but you'll need a controller.
To control the CVVT solenoid you only have to vary the duty cycle - on time.
The frequency is fixed at 250 hz.
Acceptable duty cycle ranges from 20% to 95%.
The easiest way to control it is by setting up a 555 timer to trigger a TIP120 power transistor off a boost pressure sensor.
555 fixes the frequency at 250hz and the change in boost pressure (resistance change) will retard/advance the cam as load (boost) is increased.
Basic knowledge of electronics and IC is required to implement.
Setting up a proper advance/retard setting depends on mods but for a free flowing engine with aftermarket exhaust, downpipe, intake, intercooler, etc.. added overlap can be beneficial while stock engine will be better off with less overlap.
Latest version R head gasket is MLS (multi layer steel) like a Cometic, this is the stock replacement. I got mine from Victor Reinz.
The cooling ports are different, they are staggered and will provide better cooling. Oil feed and crankcase drain ports are all compatible. If you use a non CVVT head with the MLS gasket you'll have to drill a few ports into the cooling passages in the head to get adequate cooling.
So this means a CVVT head will bolt onto a non CVVT block.
You cannot to my knowledge put a non CVVT cam in place of a cam that was CVVT.
The journals are significantly different, this is true for any potentional non CVVT cam be it earlier 870 style or later P2 style.
Obviously modification could be made to the head but it's not a drop in.
You can run a CVVT system on a car that didn't come equipped with it but you'll need a controller.
To control the CVVT solenoid you only have to vary the duty cycle - on time.
The frequency is fixed at 250 hz.
Acceptable duty cycle ranges from 20% to 95%.
The easiest way to control it is by setting up a 555 timer to trigger a TIP120 power transistor off a boost pressure sensor.
555 fixes the frequency at 250hz and the change in boost pressure (resistance change) will retard/advance the cam as load (boost) is increased.
Basic knowledge of electronics and IC is required to implement.
Setting up a proper advance/retard setting depends on mods but for a free flowing engine with aftermarket exhaust, downpipe, intake, intercooler, etc.. added overlap can be beneficial while stock engine will be better off with less overlap.
Additional Reading
Why Build?
Cylinder Head Question
What cylinder head to use for best performance with 2.3L block?
Upgrade NA cams, intake only or both?
Exact cam specifications
"2nd Gen" Whiteblock?
