Xnke Posted July 1, 2008 Share Posted July 1, 2008 Ok, so the block I purchased is not exactly what it was sold as. Not a real big deal, or so I thought. I knew the block had been "freshly" bored to 87mm, no big deal, that's great. Turns out, #1 has a sleeve in it. No problem. after a quick hone to clean the surface rust out, #5 is seriously scored and pitted. Time for new pistons, in 87.5mm bore. Does anyone know a source for these? ITM part number should be (and ITM's catalog says they make them up to 0.060" oversize) RY2701-060. Anyone know another source of oversize pistons? Quote Link to comment Share on other sites More sharing options...
1 fast z Posted July 1, 2008 Share Posted July 1, 2008 Itm does not carry anything over .040 for flat tops. Flat tops are now all sold out of the country in .040". Atleast this is what my supplier is telling me. Quote Link to comment Share on other sites More sharing options...
z-ya Posted July 2, 2008 Share Posted July 2, 2008 As 1 fast z said, they are only available up to 1mm over bore. To be honest, I would look for another block. One that has been sleeved, and has that much bore damage is not worth putting any money into. Blocks are cheap. Get one in good original condition that has not been bored and bore it to 87mm. Quote Link to comment Share on other sites More sharing options...
Xnke Posted July 2, 2008 Author Share Posted July 2, 2008 After getting the block tested today, I have no qualms about it. They pulled the sleeve in #1 out (it was a thin one, for a scored cylinder he thinks) and magnafluxed the whole block. No cracks or weak spots. My machinist told me he'd have absolutely no problems boring it as far as 90mm, although I would have a 0.92" wall thickness (just a hair under 3/32. Too thin for me.) They replaced the sleeve and bored the block to 88mm, all the bores cleaned up fine. Does this sound like it'll be ok for a NA engine? As far as getting another block, I'm stuck with this one. Already bored and cleaned up...After this engine is running, I'll start looking for another block to build...I'm sure I'll find a use for it. I did find pistons to fit, with the help of my machinist. I will look tomarrow and see what they came from. Quote Link to comment Share on other sites More sharing options...
Quin Posted July 3, 2008 Share Posted July 3, 2008 How thin is too thin on these blocks? Is there a particular block you can bore a little farther? I plan on boring out to 89MM (3.2 stroker motor, NA, 100-200 shot possible), would I run into any problems with a specific block vs another? I don't mean to thread jack, seems to be kind of in line with the OPs posts. Quote Link to comment Share on other sites More sharing options...
z-ya Posted July 3, 2008 Share Posted July 3, 2008 If you are shooting for high HP/TQ with NOS or turbo, the extra displacement is not worth the loss of structural rigidity. For you application I would not bore more than 87mm. Quote Link to comment Share on other sites More sharing options...
Xnke Posted July 3, 2008 Author Share Posted July 3, 2008 I don't mind at all, it's a valid question. I think that most bore to 89 because pistons are available, but if a 9.5cc dish is ok, 88mm pistons are available as well, using an L28 crank and L24 rods. Not sure about the LD crank, you'd have to measure carefully. Personally I would not go thinner than 0.93" wall for an engine that won't see much time, and .120" for anything reliable. Quote Link to comment Share on other sites More sharing options...
Quin Posted July 4, 2008 Share Posted July 4, 2008 I'm not shooting for crazy high numbers, looking for between 350 and 400rw with the spray, definitely not sustained. Mainly DD purposes with occasional track/street/strip racing. Maybe it's just because I'm used to the Supra world (meaning mainly 3500lb cars, but also extremely easy power), but that is pretty much normal for me. Hoping to make around 250rw NA (don't mind a high RPM powerband, so an aggressive cam is OK in my book). How thick are the cylinder walls from the factory? I've seen a couple guys running a 3.2l motor, but I thought using the L28D crank only netted you around a 3l with the stock bore of 86mm (could be off on my numbers, I'll definitely be double checking everything before I start spending money on it). By my estimation that means you need a 90mm bore to hit 3.168l, close enough to .2. I used the calculator here - http://www.ozdat.com/ozdatonline/enginedesign/ for my numbers. Btw, after doing some more calculations (okay, so I let that calculator do them for me ) it looks like 7500 RPMs would pretty much be the end of safe powerband, due to very high tensile loads on the rods. I've always heard 3550ft/min was the cutoff for gaurunteed safe and reliable motors, with 4000ft/min being the end of the reasonably-risky zone, and anything after that resulting in very short life. 7500 RPMs yields 1245m/min, which is right around 4000ft/min. Thoughts on this as well? Quote Link to comment Share on other sites More sharing options...
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