rayaapp2 Posted November 14, 2012 Share Posted November 14, 2012 I have a set of random Arias pistons. I need to measure the dome volume, but my best guestimate is about 12cc's I have one L series 240Z left with 2 engines. The original L24 is out of the car and in storage. Im considering using these pistons in it. Mind you these are not purpose built pistons for my setup. They were designed from a sample piston for some old race car. They are brand new and sitting on a shelf. Bore 3.445" / 87.5mm pin height 35.56mm full floating pins dome approx 12cc's but need to verify 87.5mm bore is pushing the L24 as I understand it. I have L24 9mm rods and a full L28 rotating assembly to work with. I also have an array of cylinder heads to work with. E88, E31, and N42 carb castings. I have been playing around with the engine calculator a bit and Im not sure they will work well with what I have. I cannot for the life of me figure out what these pistons were designed for. Maybe it was a super high compression stroker engine? Im not real sure where Im going with this if anywhere at all since they were obviously designed for some other application, but Im open to ideas that I can pick up and roll with. I figure what else am I going to use them for. Originally I purchased them for an L28 I was building and ended up going a different direction after I realized the pin height wouldnt work out the way I wanted. Ray Quote Link to comment Share on other sites More sharing options...
Xnke Posted November 14, 2012 Share Posted November 14, 2012 (edited) These pistons were designed to be run in an L28 block, with L28 crank, on L24 rods. If you have a shot of the pistons so we can see the dome shape from both the top of the piston and from the bottom side looking up under the wrist pin, we could figure what head they would fit. I would guess they were setup for an N42 cylinder head. I'm running the same compression height in my engine. Edited November 14, 2012 by Xnke Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted November 14, 2012 Author Share Posted November 14, 2012 (edited) That was the best combination I could figure out as well. The N42 and which ever E88 head I have that is similar to the N42 seem to fit the dome the best. The E31 seems to be the worst fit and the P90 I looked at just for fun works, but would not suite me as I want to keep the car with carbs(well at least a triple manifold and some TWM TB's) Pics: Edited November 14, 2012 by rayaapp2 Quote Link to comment Share on other sites More sharing options...
Gollum Posted November 14, 2012 Share Posted November 14, 2012 All things considered, it's probably designed around the N42 head. The question is, what's the compression actually going to come out to? You don't design a radical piston for pump gas compression levels... But maybe it WAS designed for a stroker and you can keep it moderate by using a shorter stroke. Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted November 15, 2012 Author Share Posted November 15, 2012 With a std head gasket 13:1 compression with the L28 crank, L24 rods, and N42 head. 2mm HKS drops the compression to about 11:1 according to the engine calc. I can bet it was not designed for a stock head. So its a matter of which fits best or start playing with combustion chambers. Quote Link to comment Share on other sites More sharing options...
roger280zx Posted November 15, 2012 Share Posted November 15, 2012 It is much easier to put carbs on a P90 than it is to bore an L24 to 87.5mm. Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted November 15, 2012 Author Share Posted November 15, 2012 It is much easier to put carbs on a P90 than it is to bore an L24 to 87.5mm. Well after talking with the locals including Dave @ Robello it seems that 87.5mm is not impossible, but its where the cylinder walls begin to get a little thin. Im not building a stroker or a turbo out of this so I may have usable results. Id honestly be happy with anything near 200hp. Which seems reasonable after seeing all the L28's and a few L24's down at MSA pulling numbers close to and just above 200hp at the wheels. Im not sure just exploring the possiblity at the moment. I do have an n42 block I can play with which would be a better canadate. Quote Link to comment Share on other sites More sharing options...
Xnke Posted November 15, 2012 Share Posted November 15, 2012 (edited) I wouldn't bore a P30 block above 85.5mm. There really isn't a lot of meat in there, any water jacket corrosion is just going to make it thinner. Honestly, I'd rock those pistons with a P90 head, 11:1 with pretty decent quench characteristics, but the piston dome does look like it'd shroud the spark plug somewhat. Hard to say without having them in hand. (plus, if you just have to run racegas, slap the P90 on with those pistons, and add boost. Triple TB's plus a plenum and some positive displacement...Yeee-Ha! Edited November 15, 2012 by Xnke Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted November 15, 2012 Author Share Posted November 15, 2012 I have 3 turbo swaps sitting in my garage to choose from and one of them has potential to be a monster L28et. I did consider using these pistons in one of my turbo builds. I figure Id keep one non-turbo L car though and 200hp at the wheels is all this car needs seeing as I have double that in both my other Z cars. I do have an EDIS 6 crank trigger setup and megasquirt v2.2 set aside for something. I bought those things for a car I no longer have. For an NA Id be worried about port work on the P90 to reach my power goals. Im not sure if it would be needed but Id guess it would. I have a mikuni manifold for the car Im thinking about doing this to. Quote Link to comment Share on other sites More sharing options...
cockerstar Posted November 15, 2012 Share Posted November 15, 2012 Not sure if the pistons will allow it, but have you considered having them milled to drop compression down to a reasonable level? Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted November 16, 2012 Author Share Posted November 16, 2012 Not sure if the pistons will allow it, but have you considered having them milled to drop compression down to a reasonable level? Yeah thats what I started to think. Without a really nice fuel management system Id rather not mess with compression and a turbo like that. I was hoping to find a way to just use these pistons as is. The high compression is really what is stopping me to be honest. Id rather just order a set of custom slugs than modify an existing set for more than one reason. Another issue with FI and 13:1 compression is that Id have to find lead friendly injectors and Im not sure such a thing exists or is reasonable in cost though admittedly I have not done the research there. Quote Link to comment Share on other sites More sharing options...
roger280zx Posted November 16, 2012 Share Posted November 16, 2012 The L28 block bored will be more reliable than a 24 at the same bore. That with a p90 head and e85 will be a monster. And a more reliable monster than it would with the 24 block. Yes 87.5 may be acheivable in a 24 block, but you might have to try 3 or 4 before you found one to work. What is the objection to the L28 block? They are a dime a dozen. Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted November 16, 2012 Author Share Posted November 16, 2012 The car has an N42 L28 under the hood right now and I didnt want to pull it to build it since I am driving it. So I was trying to find a way to use the original L24 that I have in storage. Nothing really set in stone, this is still a "what if" kind of idea. Option "B" is the LD28 currently in my maxima so Im kinda tossing ideas all over the place trying to decide where I may go down the road with this car. I really like the idea of a soy powered turbo LD28. The last maxima I had and long ago my LD28 260Z both ran bio. A rod knock ended my 260Z Diesel project though and the RB replaced that. Quote Link to comment Share on other sites More sharing options...
Gollum Posted November 16, 2012 Share Posted November 16, 2012 I think you should just throw it together and add a wild cam that doesn't really come alive till 4,000. If you can spare it, have a good dynamic balance done on the crank so you're not freaking out each time you rev it past 7,500 and just plain out run the detonation. You're not looking to get 300hp from this thing, just 200. It might not do well in an endurance setting but I doubt you'll ever push it that hard. And even if you have to give up %5 of total power due to dialing back the timing, well I don't think that's the end of the world for your goals. The worse that could happen would be that it's SO prone to detonation that you only end up with 150ish at the wheels from pulling timing. Then that just leaves you at a starting point. Then either megajolt it, or re-ramp the dizzy so you can pull timing down low and bring it back up once the wild cam kicks in. Quote Link to comment Share on other sites More sharing options...
Gollum Posted November 16, 2012 Share Posted November 16, 2012 (edited) double post.... browser doesn't like the new forum apparently... Edited November 16, 2012 by Gollum Quote Link to comment Share on other sites More sharing options...
Gollum Posted November 16, 2012 Share Posted November 16, 2012 I'm sure you could also find a AZCAR manifold to run this puppy and fret not about compression: http://www.summitracing.com/parts/qft-ss-650-e85/media/images Just about the perfect CFM for a E85 powered L motor imo. Quote Link to comment Share on other sites More sharing options...
KillerBjt Posted November 16, 2012 Share Posted November 16, 2012 Gollum i think im gonna have to disagree on the 4 barrel idea, while ok for some motors i think for such high compression it wouldn't do well enough giving a even mixture in all cylinders to make sure no detonation happens. But thats just my opinion, however i do agree with the E85 and wild cam! Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted November 16, 2012 Author Share Posted November 16, 2012 Id be afraid of mixture differences between the #1/#6 and #4/#5 cylinders on the BRE manifold I have. It obviously works as a manifold, but equal length runners takes that extra bit of tuning out and allows a more precise afr mixture across the board. 2 cents on the four barrel manifolds. I actually have a BRE manifold for sale. Gollum we spoke about E85 the other day... This would be car number 2. converting almost all my cars to either bio or E85... yikes I have everything for my ignition but the mega jolt box. COP's, EDIS, crank trigger, etc. So I will be able to dial the timing in! Ive got a stack of core cams and I was thinking of sending one off to Isky for a re-grind. I have a set of Schneider valve springs too. Id like to keep the revs below 7500rpm. In honesty Id like to keep the revs down below 7000. A cam thats alive at 3500 and carries to 7000 would be great. Quote Link to comment Share on other sites More sharing options...
Gollum Posted November 16, 2012 Share Posted November 16, 2012 (edited) Gollum i think im gonna have to disagree on the 4 barrel idea, while ok for some motors i think for such high compression it wouldn't do well enough giving a even mixture in all cylinders to make sure no detonation happens. But thats just my opinion, however i do agree with the E85 and wild cam! Have you ever tuned E85? With ethanol it's almost impossible to foul plugs and you don't lose power from being too rich like petroleum. Even though stoichiometric for E85 is around 9.7:1 it's max power windows is HUGE. For example, max power for pump gas is usually a window between 12.5:1 and 13.3:1. That's less than a 1 point window to hit. Anything from one side to the other and you can almost guarantee you're losing power. With E85 (not just straight ethanol) that window is from 6.9:1 and 8.5:1. That's over a point and a half difference and much richer ratios. If you scaled this up to look at the % differences you'll see that ethanol has THREE TIMES the rich/lean happy window for max power. So, in conclusion, though cylinder to cylinder consistency might be crucial with gasoline, it's much less crucial with E85. Just run extra fuel and you'll be okay. Gollum we spoke about E85 the other day... This would be car number 2. converting almost all my cars to either bio or E85... yikes Yea I wasn't actually expecting you to jump on that, just toying with you. Edited November 16, 2012 by Gollum Quote Link to comment Share on other sites More sharing options...
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