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rb24det questions


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So I got my hands on a RB20det courtesy of SuperDan. Thanks again. Had one of these in my first Skyline. GTS-4 2dr. Fun car. Did all the bolt on stuff to make a mini GTR before I got the big boy. Anyway I have been reading a bit about stroking this thing to a 2.4 using RB26 crank and rods and toping it off with 4agze pistons. Curious to see if anybody here has done something similar or knows someone who has. Curious to hear how happy they are with it. If not then will simply build a strong 2.0 out of it. Got GTR cams and injectors on the way and thinking of a trick turbo header set up that is on Yahoo auctions...

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Now this is only from what I have read on another nissan page...Nicocar or something like that. Using the 2.6 crank and rods gives it a larger stroke. Obviously. The bore of 82 is convienent for the 4agze piston. Which happens to be a turbo piston from toyota with ideal pin height. No big deal. According to numerous goggle searches the 2.4 has more torque and higher revs than the 2.5...Higher torque I figure is from the larger crank/rod combination and higher revs again from the 2.6 geometry. The engine was free. 4agze pistons used from japan less than $200. RB26 crank / rods no more than $500. Turbine setup with Rb25 turbo around $250...Small odds and ends and that's about the price of your average Rb20det to begin with...Rb25det are even more. Throw in costs of bearing, seals and gaskets a little machining. No real loss because that's just a good idea to do to a used engine before installing it...Just curious to find someone else here or perhaps AUS that has this or attempted for their feedback....

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very cool, im also looking into doing this. it would serve you well to look at forums such as skylinesaustralia.com of skylinesdownunder.com and take a look there. i think a few guys are running rb24s in their r30s. i think one guy was pushing 650rwhp.keep us posted on ur progress as id love to see how it turns out.

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When in the Philippines last year I discovered a factory built RB24. Nissan put this SOHC carburated motor in the export model Cefiro.

 

The info below was retrieved from Wikipedia

 

RB24s - single-cam

This is a relatively unknown engine, as it was not produced for the Japanese domestic market. These were fitted to some left hand drive Nissan Cefiros exported from Japan new. Mechanicly it is made from an RB30e head, RB25de/det block and RB20de/det crank with 34 mm heigh pistons. This engine used carberators instead of the Nissan ECCS fuel injection system. This has the outcome of it being able to rev harder than the RB25de/det (as it has the same stroke as the RB20de/det) as well as being almost the same displacment as the RB25de/det. A common modification is to fit a twin cam head from other RB series motors while retaining the carberated set-up. In standard single cam form it produced 141 PS @ 5000 rpm and 20.1 kgf·m of torque @ 4,400 rpm

 

This might be an interesting RB24DET variant to build.

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Curious to see if a RB25det headgasket would work on a Rb20det bored to 82mm. I am pretty sure the stock bore on the 25det in 85mm. Is 3 mm too much gap? Probably going to have to use a custom job. Anyway got the bottom end of the Rb20 dissassembled. Dan was right. The timing gear was not wanting to be removed easily. Had to drill and tap it to get a steering whell puller attached. Still was a bastard to crank off. Monday I have an appoitment at a machine shop to hot tank the block. Only going to set me back $35. So far this is going pretty smoothly...

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good luck with the RB24 project. from what i have seen, you will need to recess the block so the rod bolts on the bigend clear. should need to maching a 5mm deep 25mm wide semi circle

 

there are aftermarket head gaskets made for over-bored RB20s

 

i was going to build an RB24, but i will be going with a much more simple RB22, using standard preped rods and crank. I have never heard of a RB20 bottom end bending unless something stupid was done, so it should be strong enough for me.

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Z Cars Rule. I have never heard of the rob bolts interferring. Tuesday I should have the crank and rods in. I will attach the rb20 pistons and do a quick spin of the assy to see how much and where it hits. Good info...You are right about the Rb strength. I started looking into the Rb24 only because I have had pretty good luck so far getting what I need for reasonable prices...Let me know who you go thru for your overbore headgasket...

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There is one for sale in new zealand, saw it while browsing for gtr parts

http://www.trademe.co.nz/Trade-Me-Motors/Car-parts-accessories/Nissan/Engines-drive-trains/auction-62980639.htm

 

I dont think you can boe a rb20 out much, like rb25/26/30 bore as the water jacet around the bores is closer on the rb20 than the other rb's, BUT, that is only from what i have seen looking at various rb20 and 30 motors at the wreckers

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my source for the rod bolt clearancing is the tommei RB20 manual. A performace magazine over here has made the motor and went by the original instructions using the tommei pistons.

 

I am not 100% sure if they do actually hit, but if it is close, it would be better to be safe than sorry.

 

also when using the tommei pistons you need to machine a small section on top of the rod, only a couple mm though.

 

i will try to find the magazine and post more info for you.

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Z Cars Rule is correct, the block will need to be clearenced a little.

I was quoted $175 to hot tank, bore/hone and notch the bottom of the piston bores from my local machine shop.

 

These guys have the correct 83mm head gasket and can get you the CP pistons made, they quoted me $700 -> http://www.jgycustoms.com/RB20DETparts.htm

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Z Cars Rule is correct' date=' the block will need to be clearenced a little.

I was quoted $175 to hot tank, bore/hone and notch the bottom of the piston bores from my local machine shop.

 

These guys have the correct 83mm head gasket and can get you the CP pistons made, they quoted me $700 -> http://www.jgycustoms.com/RB20DETparts.htm

yah notching the underside of the block shouldnt be too much of a deal. but i wouldnt do it with an angle grinder like some custom hobby shops do.

 

i know someone personally, with a 400 crank in a 350 SBC. the thing hauls ass, but now he's suffering from some major problems, relating to probably the rotating assembly being balanced for a 400 instead of a 350, and it's thrashing the block really bad. and if it is cracked, it's probably cracked where most of his webbing was grinded off so that the rods would clear the 400 rotating circle.

 

 

 

correct me if im wrong guys.. but wouldnt you have to hone the cylinders really well to get this to actually work, as the stroke is increased, BDC is now further down the cylinder, and the cylinder walls are of unscored metal further down into the engine, so wouldn't that cause for some overly worn rings as it travels further in it's rotation!? so if and when it comes up back to TDC, the rings would then be scored to the point where they're tightly fit at the bottom, and loose at the top.

 

or do you just get by this with a tiny little bore and oversized rings

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Using the 2.6 crank and rods gives it a larger stroke...
According to numerous goggle searches the 2.4 has more torque and higher revs than the 2.5...Higher torque I figure is from the larger crank/rod combination and higher revs again from the 2.6 geometry.

 

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 18,000 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.

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