Muskrat Posted August 28, 2003 Share Posted August 28, 2003 Hi guys, as you can see, this is my first post, but I have taken the time to read around a bit to prevent myself from asking a question that has been butchered before *I HOPE*. By the way, really excellent site. I was using the Sydney Z club Engine Builder yesterday to figure out the largest bore/stroke combination i could possibly run on the street, on pump gas, using the L24 block and the E88 head that I already have in my possession. Please understand, this is all rather new to me, and is an excercise in learning. If the combination turns out to be relatively free from catastrophic flaws, I have the funds to actually make this setup happen. Now, from what I understand from a bit of research, the L24 uses the same main journal size of the L28, and the blocks are essentially the same except for the 3mm difference in bores. The combination that I ended up with after a bit of tweaking and changing parts to get the numbers i wanted was: - L24 block (stock deck height) bored out 3mm, yielding 86mm - unmilled E88 heads with 44.7cc - HKS 2mm gasket - LD28 diesel crank (83mm stroke) - L26/L28 connecting rods (130.3mm rod length) - L28 style flat top pistons, fly cut 1mm The important final numbers I came up with were: - 2893cc with 10.47:1 static compression - 83mm stoke and 86mm bore, yielding .97 stroke/bore and 1.57 rod/stroke ratios The only number that bothered me was: - 1.030 deck height (I assume this means the piston is sticking out of the hole) The questions that I have come down to what are basically reality checks: - will there be valve interferance with the -1mm deck height? - will there be problems with the top piston ring actually coming out of the bore? - can the L24 block even be overbored .120"? - will the L24 block have any internal clearance issues with the larger stroke? Almost forgot... I do realize that this would be greatly simplified by using a L28 block, as it will also yield a larger displacement, and can apparently be bored to 89mm. I would just really appreciate knowing if this would work, and I'm having fun learning. Thanks. If I happened to leave out any critical information I’m sure someone will let me know. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted August 28, 2003 Share Posted August 28, 2003 Mike, For as cheaply as you can find blocks in the JY, rather get a 2.8 block and go with a 3.1 liter. As they say, there's no replacement for dispacement (except for boost as many will argue). The 3.1 conversion has been well documented, and you should be able find lots of info here. Tim Quote Link to comment Share on other sites More sharing options...
Muskrat Posted August 28, 2003 Author Share Posted August 28, 2003 You are correct of course, a junked L28 would be a better overall deal in this situation. I have read several threads on 3.1liter stroker buildups, which is what sparked my curiousity and led to my previous post. My questions, however, are concerned with possibility, not cost efficiency. Quote Link to comment Share on other sites More sharing options...
johnc Posted August 28, 2003 Share Posted August 28, 2003 > - will there be valve interferance with the -1mm deck height? Most likely but it depends in which cam you're going to run. > - will there be problems with the top piston ring actually > coming out of the bore? The top piston ring coming out of the bore is ALWAYS a problem! I don't think that's the case here but you'll have to measure you're specific assembly. > - can the L24 block even be overbored .120"? The most I've ever heard of is .060. > - will the L24 block have any internal clearance issues with > the larger stroke? Sometimes the bottom of the cylinders need notching to clear the crank counterweights. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 28, 2003 Share Posted August 28, 2003 Boring an L24 that far would leave very little cylinder wall. Get an F54 "turbo" block and do the stroker buildup. It has a brace in the water jacket about 1/2 way up the cylinder wall to prevent the cylinders expanding under pressure. I haven't heard anyone talk about this here, but I know of a guy who built a stroker out of a 280Z block (not braced) and he got about 5K miles before it started smoking really badly. Turns out the high compression and thin cyl wall actually warped the cylinders so badly that he had to replace the block. I think he had actually damaged the pistons by the time he got to fixing it. Jon Quote Link to comment Share on other sites More sharing options...
Muskrat Posted August 28, 2003 Author Share Posted August 28, 2003 Thanks john, and jon. I'll do some research on that F54 block. Quote Link to comment Share on other sites More sharing options...
Guest eric-z Posted August 28, 2003 Share Posted August 28, 2003 I think many people will tell you that the rod/stroke ratio is to low ... just thought I would throw that out there... Quote Link to comment Share on other sites More sharing options...
TimZ Posted August 28, 2003 Share Posted August 28, 2003 > - will there be valve interferance with the -1mm deck height? Most likely but it depends in which cam you're going to run. > - will there be problems with the top piston ring actually > coming out of the bore? The top piston ring coming out of the bore is ALWAYS a problem! I don't think that's the case here but you'll have to measure you're specific assembly. On the valve interference issue, remember that he is specifying a 2mm head gasket - shouldn't this be the same as zero deck height and a standard 1mm head gasket? You do still need to check on the top ring, though. Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted August 29, 2003 Share Posted August 29, 2003 My daily driver is getting a similar treatment to what you are contemplating. I am however using the 280 block, .40 overbore, LD28, L28 rods and dished pistons shaved 1mm, 2mm gasket. The problem you will find is that the L26/L28 rods are very short for this set-up. I had to have a bunch of material taken off of the crankshaft counterweights and the piston skirts.... and then rebalancing the rotating assembly... if you are dead set on the L24 block LD28 crank, you may also run into connecting rod, piston bore clearance issues... I'd probably recommend buying custom pistons and using your L24 rods. You'll be close to the same price, maybe further ahead. I only wish I would have done that now... Oh well, another experiment in L-engine_ering Quote Link to comment Share on other sites More sharing options...
Muskrat Posted August 29, 2003 Author Share Posted August 29, 2003 Z-Gad, it looks like I didn't give enough consideration to why people use the KA24 piston with L24 rods on thier stroker buildups. All of the L24-28 pistons use the same overall piston height and use a pin height of 38.10mm. The KA24 pistons use a pin height of 34mm, which essentially puts less piston above the pin. The shorter piston allows the use of the longer L24 rod. The thing that I have noticed is that regardless of whether you use the L24 rod/KA24 combination or the L28 rod/L28 piston setup, you end up with a positive deck height. Both will require milling the piston and/or the use of a 2mm headgasket. Even after milling the piston on the L28 rod setup, you still have a 1.030mm positive deck height. It makes a bit more sense now that I've had some more time to look at it. Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted August 29, 2003 Share Posted August 29, 2003 Hey Muskrat, you can mill the pistons by hand .015" and then use two stock headgaskets sprayed with copper sealant on both sides for the right clearance. You end up with a 2.9L with the stock L28 rods and pistons. I have run this combo on the street and raced at the track for over 4 years now. It's cheap and effective. later Quote Link to comment Share on other sites More sharing options...
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