Blobber Posted October 11, 2007 Share Posted October 11, 2007 I have wondering if anybody here has build a L26 turbo engine with p90 head. I looked from ozdat.com that it would be possible. Compression ratio would drop a bit and I think that just would give me more reliability. Has anyone done this? Also I'm considering to use the stock manifolds from 280zx turbo to build-up a turbo conversion to the engine. How does this sound? Am I going to face huge troubles with building this conversion? I aiming eventually to +300hp(not aiming to get these powers right away). How would the l26 rods, pistons and crank last the stress in the beginning(around 250hp)? I thing I have to go for forged pistons later on, when aiming 300hp, but would the l26 crank and rods last this kind of stress? I found something with search but nothing with p90 head. Quote Link to comment Share on other sites More sharing options...
Gareth Posted October 11, 2007 Share Posted October 11, 2007 A entirely stock L26 engine with a P90 head should have a compression ratio of 7,3:1. I think that's too low for you, and 8-8,5:1 should be quite safe with your 98 octane petrol. I'd get a set of forged pistons even before you drop the turbo in, just for safety. For the power you're aiming for, stock manifolds should be OK. I'm not sure about the strength of the L26 internals, but if I were you, I'd upgrade everything that's within your financial capabilities. Good luck! Tony Quote Link to comment Share on other sites More sharing options...
X64v Posted October 11, 2007 Share Posted October 11, 2007 I'm running 8.8:1 compression on my bonestock '73 l24 longblock, running 7psi on 91 octane. No intercooler, even pulled hot air from the engine compartment while it was 110 outside here in the desert, no detonation, no problems. '73 E88 head btw. The rods and crank in that l26 shouldn't be any weaker than in an l28. Some info is floating around that says that l28et rods were shot peened from the factory, but other than that they're they same as the other rods. People have used l24 rods successfully, as well as l28e rods and cranks. Quote Link to comment Share on other sites More sharing options...
Blobber Posted October 11, 2007 Author Share Posted October 11, 2007 But isn't lower compression ratio better for reliable engine? Also doesn't L28ET compression ratio around 7? Also I have read that better to have little bit lower compression so you can add more boost to the engine. What would better EFI head for my engine than p90? n47? Quote Link to comment Share on other sites More sharing options...
Shuyun Posted October 11, 2007 Share Posted October 11, 2007 Stock Compression on an L28et is 7.41 to 1 as you lower compression ration you can add more bost so you have more power on the top end but you loose power on the low end. Compression ratios of 10 to 1 can run on pump gas NA and as high as 12 to 14 to 1 with acholol or propane I cant really remember the limit. Quote Link to comment Share on other sites More sharing options...
stprasinz Posted October 11, 2007 Share Posted October 11, 2007 Stock Compression on an L28et is 7.41 to 1 as you lower compression ration you can add more bost so you have more power on the top end but you loose power on the low end. Compression ratios of 10 to 1 can run on pump gas NA and as high as 12 to 14 to 1 with acholol or propane I cant really remember the limit. Actually 93 octane doesn't begin "uncontrollable" detonation until 15 to 1. As in when 93 octane reaches 15 to 1 it detonates.... I don't know how true this is.. I was running 93 octane on a turbo... the comp. was close to 7.5 to 1 But at 24 psi of boost the final compression ratio is way past 15 to 1... Which makes my fcr almost 20 to 1..... (19.4861xxxxxxxxx)......... And thats with stock type pistons no meth injection.. just an intercooler...... Just food for thought.. And I have a friend with a 15 to 1 compression 6 cyl that runs 118 leaded...... Alcohol is more resistant to detonation isn't it..... Ok I'm rambling and babling....... Probably no sence to half of what I say any way... Quote Link to comment Share on other sites More sharing options...
Blobber Posted October 12, 2007 Author Share Posted October 12, 2007 But when people are converting l28 n/a to turbo, people are suggesting to find pistons and rods to lower the compression ratio(l28 n/a close to L26 compression) and get a stronger setup. shouldn't this be done with L26 turbo conversion? Quote Link to comment Share on other sites More sharing options...
TravRMK Posted October 12, 2007 Share Posted October 12, 2007 That is mostly for the flattop pistons used in the later NA F54 block L28 (81-83) The earlier L28's have esentially the same pistons as the turbo motors with the 81-83 turbo's having slightly larger ring lands than the early l28 dished pistons. Quote Link to comment Share on other sites More sharing options...
TravRMK Posted October 12, 2007 Share Posted October 12, 2007 Also the L26 has the same crank and rods that the L28 does. Quote Link to comment Share on other sites More sharing options...
Blobber Posted October 12, 2007 Author Share Posted October 12, 2007 The earlier L28's have esentially the same pistons as the turbo motors with the 81-83 turbo's having slightly larger ring lands than the early l28 dished pistons. You mean the 280z l28 or the 280zx l28e? Or are those the same engine? What else do you gain with flattop pistons than the lower compression ratio? Quote Link to comment Share on other sites More sharing options...
boardkid280z Posted October 12, 2007 Share Posted October 12, 2007 Does this data look correct to everyone? I had a P90 head +Turbo on my L28 flattop shortblock before I threw a rod bearing. Then I swapped it all onto a L26 flattop block, been running 8psi boost for a while now no problems. Quote Link to comment Share on other sites More sharing options...
TravRMK Posted October 13, 2007 Share Posted October 13, 2007 You mean the 280z l28 or the 280zx l28e? Or are those the same engine? What else do you gain with flattop pistons than the lower compression ratio? The 75-80 L28's (N42 block) have dished pistons stock. The 81-83 non turbo (F54 block) have flat top pistons. Quote Link to comment Share on other sites More sharing options...
Blobber Posted October 14, 2007 Author Share Posted October 14, 2007 So your all saying that I should go with like n47 head than the p90. Compression ratio with n47 head is 8,3:1 and p90 with would be around 7,3:1 With which head would I get more reliable setup? which would be better for over 300hp setup? Quote Link to comment Share on other sites More sharing options...
CantZme Posted October 14, 2007 Share Posted October 14, 2007 IMHO, this doesn't really sound like a bad idea at all; however, what are you planning on using for fuel control? I'm not sure if the quench of the p90 head will be ruined with the L26 flattops, but as you read above...it's been done and it was sucessful (I'm assuming with no detonation lol). A stock l28et can take upwards of 300whp on pump gas, so with the stock T3 turbo, p90 head and the l26 block some race fuel, I think your goal, 300hp(not whp) should be attainable, but not without an intercooler and race fuel(just to be safe). If you haven't looked into megasquirt for fuel control, you might want to check it out...but be prepared to learn A LOT. Good luck and keep us updated if you decide to actually do this, this should be interesting. Quote Link to comment Share on other sites More sharing options...
David K Posted October 14, 2007 Share Posted October 14, 2007 So your all saying that I should go with like n47 head than the p90. Compression ratio with n47 head is 8,3:1 and p90 with would be around 7,3:1 With which head would I get more reliable setup? which would be better for over 300hp setup? You need to match the head with the pistons you are using. P head should go with flat pistons, and N heads should go with dished pistons. Quote Link to comment Share on other sites More sharing options...
CantZme Posted October 14, 2007 Share Posted October 14, 2007 So your all saying that I should go with like n47 head than the p90. Compression ratio with n47 head is 8,3:1 and p90 with would be around 7,3:1 With which head would I get more reliable setup? which would be better for over 300hp setup? The p90 head is going to result in lower compression, so detonation would be less of an issue here. More boost = more power and with less compression, you can run more boost. Although you can have a great setup with the n47 head, its easier to tune a low compression motor. That one whole point in compression might not be worth the few extra pounds of boost you can run with a 7.3CR. BTW you can always look at it as traction control, since a lower compression motor will result in longer spool! Quote Link to comment Share on other sites More sharing options...
datman Posted October 14, 2007 Share Posted October 14, 2007 I'm running NA f54 flat top pistons...dropped the CR to 8.35:1 by using a 2mm steel head gasket and p90 head...large intercooler and a Holset turbo is around the 350HP mark. Just keep the inlet charge cool and retard the ignition a little more than the stock turbo you should be fine Quote Link to comment Share on other sites More sharing options...
Blobber Posted October 14, 2007 Author Share Posted October 14, 2007 well, EMS is going to be updated also when building the engine. Megasquirt is most obvious choice, but other options haven't been ruled out. Megaquirts tune-up is the main consider. I going to use just normal gas and car is going to be daily-driven in the summer time. cantZme, are you serious about what you saying that L26 pistons, stock t3 and p90 head need racing fuel? Sounds bit of odd...(well, I new with these things so everybody can trick as much as they like). Also I'm going to put intercooler to the setup. I'm aiming for over 300hp eventually, but not yet. But I want to build everything from the beginning with that in mind. I know that before I going to reach over 300 hp, I should go for forged pistons. So the setup what I have quickly thinked of is that I'll use otherwise stock L26, but with changing head and adding EFi with l28et intake and exhaust manifold I could build a turbo efi setup. Of course I need other parts also, but this would be this winters idea to what I'm going to build. Quote Link to comment Share on other sites More sharing options...
datman Posted October 14, 2007 Share Posted October 14, 2007 No need for forged pistons at that HP..the staock cast ones are good for that if you make sure you have enough fuel and the ignition set right. If you aim for around 8 to 8.5:1 CR then it will drive nicely off boost and respond very well. Fit a turbo oil pump and use ARP crank, rod and head bolts. Quote Link to comment Share on other sites More sharing options...
Blobber Posted October 15, 2007 Author Share Posted October 15, 2007 I'm running NA f54 flat top pistons...dropped the CR to 8.35:1 by using a 2mm steel head gasket and p90 head...large intercooler and a Holset turbo is around the 350HP mark. Just keep the inlet charge cool and retard the ignition a little more than the stock turbo you should be fine But with this setup I counted 6,9:1 compression ratio with ozdat.com or did I understand something wrong? Or is there a mistake in ozdat.com? Quote Link to comment Share on other sites More sharing options...
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