z_cars_rule Posted July 17, 2006 Share Posted July 17, 2006 i dont think you have to bore it that much, you are only gaining .2L from the bore, spread over 6 cyls, i think it is only a 1 or 2 mm overbore. When i was considering doing it i was going to either get the tommei pistons or come CP units. Quote Link to comment Share on other sites More sharing options...
greenmonster80 Posted July 17, 2006 Author Share Posted July 17, 2006 Well to get the 2.2 or 2.4 the bore must be increased to 82mm. Tomei sells the pistons...Big money though. Their website states as well if you want to go to the 2.4 the 2.6 crank and rods are necessary. Leads me to believe that the 2.4 is safe enough. Tomei is about as well respected as they come..But I understand the concern...Got the block stripped down this afternoon. Will be taking it n to be clean tomorrow... Quote Link to comment Share on other sites More sharing options...
cheftrd Posted July 17, 2006 Share Posted July 17, 2006 Also, as the RB piston pin is 21mm and the 4AGZ pin is 20mm, you must have the rods re-bushed with custom fit bushings, or the pistons bored and grooved for the 21mm pin and clips. Custom pistons are looking cheaper and cheaper. Or, you could just go with the RB25, with bigger valves, ports, etc. and make way more power. You could use the RB26 crank and rods you have to make it 2.6 with no mods. I've been in Japan for over 20 years, off and on, and have been working on RB's since about 1989. I've seen a total of two (2) RB24's because: 1. They were both built before the RB25 or 26 (see #2) 2. Once the 25 and 26 came out in the R32, the power output in the 2.4 seemed anemic, especially when you consider the significant cost of building the 2.4 vs. the larger output of the basically stock 25/26. 3. They are (extremely) prone to breaking cylinder walls. Both engines were brought to be for "problems". Both had cracked cylinder walls, bent rods, etc. (catastrophic failure). Not trying to rain on your parade. Just giving you some insight from someone who has actually been down this road. Quote Link to comment Share on other sites More sharing options...
fraz Posted July 17, 2006 Share Posted July 17, 2006 As far for my experience on how high the engine revs goes I think if you simply stroke the engine and leave the bore this would make the engine under square (meaning that the bore is smaller than the stroke). This under square engine will not rev as high as an over square (larger bore than stroke) engine of the same displacement. Formula 1 engines are over square engines and rev to about 18' date='000 rpm, aslo they are only 3.0L of displacement. I dont know of another V-10 so I will use the VG30E for an example... the VG30E only revs to 6500-7200 rpm, the vg30e is under square. I know that if you put enough money into any stroker engine it can rev more than just a plain stroker. But most of the time a daily driver will not do this and will only do this if there is a return to their investment? Someone correct me if I am wrong on this math. This is what I have learned about making an engine scream with RPM's.[/quote'] The powerband of the motor is more determined by the rod ratio than the bore/stroke ratio. The rod ratio is the ratio of rod length to stroke. Have a bit of a google about it, there is a lot of info out there, cant remember any links off the top of my head. A good example is the honda b series, b16/b18/b20 all have same block, just different crank/rods/pistons to change displacement. the b16 will pull 10,000 rpm with good valve springs, but the b20 pistons and rods will start to let go around 7500-8000, this is due to the short rods. hope this helps Quote Link to comment Share on other sites More sharing options...
greenmonster80 Posted July 17, 2006 Author Share Posted July 17, 2006 Cylinder walls cracking are bad. I am pretty sure the bottom end will be ok it will be all GTR parts. Maybe I will look at 81m pistons instead. Speaking of pistons this is frustrating. Ausie webpages talk about the 4agze pistons being 82mm. After ChefTRD's post I look at Hatchi pages. They state pistons are 81mm. WTF..Looks like I will go CP and forget about it... Quote Link to comment Share on other sites More sharing options...
cheftrd Posted July 17, 2006 Share Posted July 17, 2006 4AG standard is 81mm. Toyota sells oversize to 81.5mm. HKS sold the stroker kit for the RB20 "back in the day". Now with the RB25/26 parts available, it has become much more economical. If you are dead-set on this, I would go with the 26 internals if you have them, and custom forged pistons at no more than 81mm. I'll look around for a junk 24 piston that you may be able to use as a sample for pin height/size when ordering custom. Quote Link to comment Share on other sites More sharing options...
jdizzy204 Posted July 17, 2006 Share Posted July 17, 2006 just go with tomei rb20 pistons. Quote Link to comment Share on other sites More sharing options...
Administrators SuperDan Posted July 18, 2006 Administrators Share Posted July 18, 2006 just go with tomei rb20 pistons. Hmmmm.... ~$1500.00 for Tomei pistons or ~$700.00 for a set of CP's.... tough choice. Quote Link to comment Share on other sites More sharing options...
greenmonster80 Posted July 18, 2006 Author Share Posted July 18, 2006 ChefTRD if you can find a piston to use as a reference much thanks. I have some GTR pistons somewhere. Thinking of using them as a guide only in 81mm size. CP will be where I get the pistons. Price is to good to pass up... Quote Link to comment Share on other sites More sharing options...
jdizzy204 Posted July 18, 2006 Share Posted July 18, 2006 Quote Link to comment Share on other sites More sharing options...
greenmonster80 Posted July 19, 2006 Author Share Posted July 19, 2006 Well I have determined there is a bunch of crap on the internet concerning Hybrid RB builds. Does anybody know of and engine calculator that I could plug RB parts into to get for sure numbers. I am now looking to go no bigger than 81mm for bore size. Also got some N1 cams on the way. When I pick up the block today from being cleaned I will drop off the head to be cleaned. Next bit of business will be measuring the main bearing area on both the crank and block. Any ideas what they should be... Quote Link to comment Share on other sites More sharing options...
jdizzy204 Posted July 20, 2006 Share Posted July 20, 2006 try to get in contact with this guy about that... http://www.meggala.com/main.htm Quote Link to comment Share on other sites More sharing options...
greenmonster80 Posted August 1, 2006 Author Share Posted August 1, 2006 Ok so the Rb26 cams bolt in but I have learned a few more mods are required to make this work. Instead I am thinking of installing the Rb20de cams. If I remember correctly they are just a bit bigger versus the turbo models. Adjust the timing and I should be good. I have almost completed re-assy of the motor to make sure I am not missing anything. I have a pretty good list so far that I will knock out during my upcoming visit to Okinawa. Anybody know someone who has tried the Rb20de cams? Curious to hear if they are worth the trouble. Boosted Rb20's are fun to begin with so I am not looking to spend alot for aftermarket cams. Just something a little bit more with low hassle. The Rb20de cams are easy to get. Quote Link to comment Share on other sites More sharing options...
greenmonster80 Posted August 5, 2006 Author Share Posted August 5, 2006 Well decided against using junkyard parts for the cams. Looking to install some HKS or Tomei might as well get the adjustable sprockets as well. Also I recently purchased a used HKS cast amnifold with a T04 turbine and HKS wastegate. I will have the turbine rebuilt just because it is a used item and better safe then sorry. Manifold has a small crack easy to repair. Got them for under $300. Pretty happy with that. Motor is completely assembled. Looks like I will need a water pump, oil pump, bearings and gaskets and replace 2 water lines that have been cut. Going to dive in the junkyard for a cefiro turbo boot and cross over pipe. This will let me add an atmospheric blowoff valve instead of the recirculating skyline version. Plus it will get rid of some vaccum lines as well. Here is the link for the turbine set up if anyone is interested. Gotta love yahoo Japan... http://page13.auctions.yahoo.co.jp/jp/auction/r28771458 Quote Link to comment Share on other sites More sharing options...
jdizzy204 Posted August 6, 2006 Share Posted August 6, 2006 are u not going to use an aftermarket rb20 intake manifold instead of a stock one with a crossover pipe? Quote Link to comment Share on other sites More sharing options...
greenmonster80 Posted August 6, 2006 Author Share Posted August 6, 2006 From what I have read the stock upper manifold flows about as well as one could need. Just doesn't look as bad ass as forward facing plenum's. I want to motor to still appear as a moderate Rb20. The turbine set up will give it away a bit. However no one will be able to see it as a stroker with cams and injectors. A good tune will really make this a low budget, reliable powerhouse. Quote Link to comment Share on other sites More sharing options...
greenmonster80 Posted August 8, 2006 Author Share Posted August 8, 2006 Came across this site today. Pretty interesting stuff. May purchase the headgasket from them. Possibly a timing belt as well. Just thought I would put it up in case someone else is interested...https://www.rhdjapan.com Quote Link to comment Share on other sites More sharing options...
greenmonster80 Posted September 27, 2006 Author Share Posted September 27, 2006 So While I was on family vacation I was able to get my hands on a few parts for the motor build. Added a N1 oil pump and water pump. New bearings and seals with gaskets. HKS cast manifold with external wastegate and T04 turbine. Turbine has a polished intake housing. Further down the list is going to be the 80.5mm pistons from CP, Metal headgasket and cams. After 4 round trip tickets to Okinawa and other expenses from being there I need to recoup some money.... Quote Link to comment Share on other sites More sharing options...
z_cars_rule Posted September 27, 2006 Share Posted September 27, 2006 good to hear its all coming together, keep us updated through the build Quote Link to comment Share on other sites More sharing options...
Careless Posted September 27, 2006 Share Posted September 27, 2006 Does anybody know of and engine calculator that I could plug RB parts into to get for sure numbers. I feel quite low for having not updated myself in regards to this thread, as I was interested initially, and still am. Here is an engine calculator. If I knew you were still going about this beast, I would have posted it way earlier. I hope you can use it, still: http://www.ozdat.com/ozdatonline/enginedesign/ Quote Link to comment Share on other sites More sharing options...
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