hatchsub Posted April 11, 2010 Share Posted April 11, 2010 (edited) I have been thinking of doing this for some time now and i think its getting closer to the time when i will actually dive in. I do have a a few questions though. I had a rough game plan worked out that involved: -Heads done by Jerry Demoss -delta cam (probably hp grind but not sure just yet) -SPFI pistons -Single weber tuned....for now -and possibly new everything like bearings and such-mind u this is going into a EA81 with barely 53k miles on it. Here is the wrench thrown in the mix though from that formula. I have the opportunity to purchase some domed pistons for an EA81 made by an aftermarket company that no longer exists. I dont know what it would do to the compression ratio or the valve clearance because i have seen how high up on the block the SPFI pistons go and there is virtually no clearance with those if i were to deck the heads .030. Here is a picture of the pistons he sent me. Or would it be a matter of...if i were to use these pistons i dont deck the heads at all? Thoughts? Im just worried that it will be too much and i wont be able to run it on pump gas or that the pistons will be the wrong sizes ( i know that there is an A and a B size piston). Let me know. Edited April 11, 2010 by hatchsub Link to comment Share on other sites More sharing options...
Psyko Posted April 11, 2010 Share Posted April 11, 2010 You could always let me test them out and see how they work. Link to comment Share on other sites More sharing options...
Turbone Posted April 11, 2010 Share Posted April 11, 2010 Wow, those look like you would have 0 clearance, even without decking. Might even have to get thicker head gaskets. Need to know how high the dome is, then calculate how much space you have in the head. Link to comment Share on other sites More sharing options...
Txakura Posted April 11, 2010 Share Posted April 11, 2010 Holy Crap Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 11, 2010 Share Posted April 11, 2010 (edited) SPFI pistons would give you 9.5:1....... much higher than that and you'll be running premium if not avgas. Those things look like they might put it up to 11:1 or higher..... I don't think that's what you want since you can't easily get 120 octane fuel...... I mean - they have a cut-out for the plug electrode..... good god man! Looks like something you would see for a deisel conversion GD Edited April 11, 2010 by GeneralDisorder Link to comment Share on other sites More sharing options...
Txakura Posted April 11, 2010 Share Posted April 11, 2010 what about water injection? kind of assuming this isn't a DD... those pistons would be really tempting, but it'd be 92 octane or higher for sure Link to comment Share on other sites More sharing options...
Qman Posted April 11, 2010 Share Posted April 11, 2010 (edited) First, the pistons and head cc's make up the compression. So, SPFI will not guarrantee 9.5/1. The best combination I came up with was; Hydraulic heads(large valve) - blended ports 1600 pistons Decked .020 - any more and you'll have problems installing the intake Port matched intake adapter for the Weber Weber 32/36 with the biggest jets I could find lightened EA82 flywheel XT6 clutch assy. Cam of your choice. I built two of these motors for myself and a couple of them for board members. McBrat has one and so does Edrach. There really is no comparison. Turbone is driving one of them and Breeke is driving the other one. Breekes replaced an EA82 with the one with the torque cam. Turbone is driving my old BRAT with the HP cam. That BRAT constantly set fast times at local rallycross events. It has a few other goodies as well though. I could run down a friends slightly modded turbo wagon with out a problem. He was just slightly disappointed when that happened. The only combination that would be better than these would be a set of RAM heads. But, those cost more than a lot of the vehicles here. Did those pistons come from NSI in Arlington, Washington? You do not have to worry about "zero" clearance on a gear-driven motor. The biggest thing would be the fuel availibilty for such pistons and the compression they would generate.. Since they were designed for gyro and ultra-lights they usually had access to av-gas, do you? Edited April 12, 2010 by Qman Link to comment Share on other sites More sharing options...
Turbone Posted April 11, 2010 Share Posted April 11, 2010 First, the pistons and head cc's make up the compression. So, SPFI will not guarrantee 9.5/1. The best combination I came up with was; Hydraulic heads(large valve) - blended ports 1600 pistons Decked .020 - any more and you'll have problems installing the intake Port matched intake adapter for the Weber Weber 32/36 with the biggest jets I could find lightened EA82 flywheel XT6 clutch assy. Cam of your choice. I built two of these motors for myself and a couple of them for board members. McBrat has one and so does Edrach. There really is no comparison. Turbone is driving one of them and Breeke is driving the other one. Breekes replaced an EA82 with the one with the torque cam. Turbone is driving my old BRAT with the HP cam. That BRAT constantly set fast times at local rallycross events. It has a few other goodies as well though. I could run down a friends slightly modded turbo wagon with out a problem. He was just slightly disappointed when that happened. The only combination that would be better than these would be a set of RAM heads. But, those cost more than a lot of the vehicles here. Did those pistons come from NSI in Arlington, Washington? You do not have to worry about "zero" clearance on a gear-driven motor. The biggest thing would be the fuel availibilty for such pistons and the compression they would generate.. Since they were designed for gyro and ultra-lights the usually had access to av-gas, do you? Yeah, I remember that lol Link to comment Share on other sites More sharing options...
hatchsub Posted April 12, 2010 Author Share Posted April 12, 2010 Ok everyone answered that question. Those are out. Thanks guys. Game plan back on track New question....will a stock 2wd clutch with about 30k miles on it now hold up to the 100 or so hp that i think my motor will make when done? Btw those are on ebay if anyone else wants a go at em Link to comment Share on other sites More sharing options...
Qman Posted April 12, 2010 Share Posted April 12, 2010 Ok everyone answered that question. Those are out. Thanks guys. Game plan back on track New question....will a stock 2wd clutch with about 30k miles on it now hold up to the 100 or so hp that i think my motor will make when done? Btw those are on ebay if anyone else wants a go at em If driven conservatively, yes. Otherwise, no! Link to comment Share on other sites More sharing options...
Durania Posted April 12, 2010 Share Posted April 12, 2010 Wow. Bet that would be fun to go through the gears on. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 12, 2010 Share Posted April 12, 2010 The good news is that you can just use the later 4 speed 225mm flywheel/clutch setup. It will bolt right up and the disc has the same splines as the 2WD disc. You just need to source a 4WD flywheel and have it properly surfaced. GD Link to comment Share on other sites More sharing options...
Qman Posted April 12, 2010 Share Posted April 12, 2010 (edited) I would look at using, at the very least, an EA82 clutch and flywheel. Anything less and you run the risk of slippage. An XT6 assy would be slightly over-kill but would not slip under load. Edited April 12, 2010 by Qman Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 12, 2010 Share Posted April 12, 2010 (edited) I beleive that is also possible if you use the right T/O bearing - I think some older threads have discussed using a T/O for either a Nissan or Isuzu truck of some kind. I've never tried it personally but that is the biggest obstical to using the 5 speed/XT6 pressure plate with the 2WD or 4 speed transmissions. Also - if you have the flywheel cut right - you shouldn't have any slippage problems with the 4 speed 225mm clutch. On my wagon I can easily chirp the 28" tires with a stock EA81/4 speed. I don't think slippage would be a problem if the clutch is new and the flywheel is cut properly. At least that's been my experience. The 200mm clutch would slip like mad just taking off from a light with the 28's - once I put in the 4WD clutch though it became a non-issue. GD Edited April 12, 2010 by GeneralDisorder Link to comment Share on other sites More sharing options...
Qman Posted April 12, 2010 Share Posted April 12, 2010 I beleive that is also possible if you use the right T/O bearing - I think some older threads have discussed using a T/O for either a Nissan or Isuzu truck of some kind. I've never tried it personally but that is the biggest obstical to using the 5 speed/XT6 pressure plate with the 2WD or 4 speed transmissions. GD No, you use the throwout bearing for the transmission you are using. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 12, 2010 Share Posted April 12, 2010 No, you use the throwout bearing for the transmission you are using. Well - I wouldn't be comfortable with the stock 2WD/4 Speed T/O as it doesn't contact the 5 speed/XT6 pressure plate fingers correctly at all. It barely touches them at the outer edge of the T/O. It might work for a time - but with a little wear to the pressure plate fingers it would go right through them. GD Link to comment Share on other sites More sharing options...
Qman Posted April 12, 2010 Share Posted April 12, 2010 They touch just fine. The only reason to use the that TO bearing is that it matches the fork. But, if you are comfortable with it you can use a 4wd TO. Mounts up the same. And, if you are really worried about it you can use a 4wd wagon bearing... Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 12, 2010 Share Posted April 12, 2010 From what I understand - the Nissan truck T/O mounts up the same - IE: it will mount to the T/O "holder" for the EA transmission. It's just larger in diameter so provides a more correct PP finger contact. What is the difference between a 4WD and a 4WD wagon T/O? I'm assuming you mean for 4 speed's..... I haven't seen a difference between any of the 4 speed 4WD T/O's..... GD Link to comment Share on other sites More sharing options...
Qman Posted April 12, 2010 Share Posted April 12, 2010 Rick, from what you understand? You haven't done one of these? I have done several. It will be fine. It will hold the power better than a stock clutch. The build will need better holding power. The clutch I recommended will do the job as stated. Subaru calls for two different TO's for 4wd's. Wagons and non-wagons. I would guess for the difference in weight. Otherwise, who knows, it could be superseded by now any way. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 13, 2010 Share Posted April 13, 2010 Rick, from what you understand? You haven't done one of these? No. But I have mocked up the parts and also have had a T/O bearing lock up and wear through the PP fingers even with proper contact.... and I've seen plenty of PP's with wear on the T/O contact surfaces. I'm not saying it won't work - just that I would be concerned about it's longevity with ~1/8" of the OD of the T/O touching the fingers. Seems like it wouldn't last is all I'm saying. I'm sure it would *work* - just not comfortable with what I see looking at how the parts mate up. And if there's a larger diameter T/O availible that will correct this issue - why not investigate the possibility? What's wrong with at least taking the time to check it out? I have done several. It will be fine. It will hold the power better than a stock clutch. The build will need better holding power. The clutch I recommended will do the job as stated. I agree the holding power of the XT6 setup is a good call. Just want to make sure it's going to give years of service for him. Subaru calls for two different TO's for 4wd's. Wagons and non-wagons. I would guess for the difference in weight. Otherwise, who knows, it could be superseded by now any way. Maybe that is the key - I'll see if my dealer can answer as to the physical difference if the part numbers are still different. They are pretty cool about such things. GD Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 13, 2010 Share Posted April 13, 2010 (edited) Ok - some numbers: EA82 4WD 5 speed T/O bearing: OD: 3.15" (but the PP contact "bump" is slightly inboard of the OD due to the stamped steel design) EA81 4WD 4 speed T/O bearing: OD: 2.5039" (Bore: 1.5748" - to mount to T/O bearing holder) 1990 Nissan D21 Pickup (2.4L 4 cylinder) T/O bearing: OD: 2.8898" (PP contact "bump" is right on the OD) (Bore: 1.5748" - same style mount as EA81 - on cast bearing holder) If it's me - I'm useing the XT6 kit like Ken sugests - but with the Nissan T/O. For the extra $25 it's just peice of mind. But.... it's a judgement call I suppose. GD Edited April 13, 2010 by GeneralDisorder Link to comment Share on other sites More sharing options...
GTlegs Posted April 13, 2010 Share Posted April 13, 2010 Dont want to sound like an idiot, but can someone please enlighten me why 1600 pistons are good. Do they give more compression or something? Link to comment Share on other sites More sharing options...
asis Posted April 13, 2010 Share Posted April 13, 2010 And along those lines, since it seems ea71 pistons will fit ea81 block then will an ea81 crank work in a ea71 block. Heads interchange? I didn't find any thing in search that gave much specifics if any info...:-\ Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 13, 2010 Share Posted April 13, 2010 Crank and heads - no they won't interchange. Pistons will interchange across all the 92mm bore engines - EA71/EA81/EA82. The EA71 pistons are taller from the wrist pin to the top of the piston - by around .010" IIRC. It bumps the compression up from 8.7 to around 9.5 GD Link to comment Share on other sites More sharing options...
Txakura Posted April 13, 2010 Share Posted April 13, 2010 Crank and heads - no they won't interchange. Pistons will interchange across all the 92mm bore engines - EA71/EA81/EA82. The EA71 pistons are taller from the wrist pin to the top of the piston - by around .010" IIRC. It bumps the compression up from 8.7 to around 9.5 GD ok I have to ask, what if the EA71 pistons went in an EA82? (which started at 9.5:1?) Link to comment Share on other sites More sharing options...
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now