Datsun Deron Posted July 2, 2012 Share Posted July 2, 2012 (edited) Hi all, I thought I'd post my findings on tuning my car for the archives. I've been running flat top pistons, a stock turbo from an 84 300zx (same size as a 280zx turbo), 7 psi and a P90 head for a couple years now and decided it was time to start turning up the boost. I purchased a manual boost controller from ebay and installed it last weekend. I think it cost around $20 dollars. The hardest part of the tuning was getting the boost set properly on the manual boost controller. Mine was pretty sensitive. 1/2 a turn made a difference of 3-4 psi. For the first few full turns until you find the sweet spot it made no difference at all. After some very brief 15 PSI spikes I was able to get the thing set to 10 PSI (where i wanted it). Once we started tuning with higher boost the flat top and p90 combo becomes a detonation machine. The most timing I could run at 10 PSI (165 KPA) was 14 degrees. The one other restriction that might affect my tuning is the fact that my air filter is located behind my radiator. I'm hoping to relocate this in the near future and will post again later if this allows me to advance the timing any further. As for a power difference it was hard to tell on the butt dyno since we were tuning while driving uphill (where I drive its primarily flat) but I do believe that the car is faster despite having to pull so much timing out. I think I will likely leave the car at 10 psi for now until I can get my hands on a meth injection kit. But then again that little knob is just waiting to be turned . Edit - I should note I'm also running 94 octane fuel Here's my ignition table to date: Edited July 2, 2012 by Datsun Deron Quote Link to comment Share on other sites More sharing options...
ozzzzz Posted July 2, 2012 Share Posted July 2, 2012 Do you have an intercooler? Intercooling makes a big difference with how much boost you can run without detonation. Quote Link to comment Share on other sites More sharing options...
Datsun Deron Posted July 2, 2012 Author Share Posted July 2, 2012 Sorry I should have mentioned in the post incase it got missed in my signature. I'm currently running a Spearco intercooler with MS-2 and EDIS Ignition. Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted July 2, 2012 Share Posted July 2, 2012 I have found with mine (I don't recall if I have flat tops or not, need to check again), that at around 6 PSIG, up to around 9 PSIG I get some detonation at anything less than ridiculously rich (fatter than my WBO2 reads), but once past that the detonation goes away rapidly. It seems to be related to intake temps, more than actual boost pressure. When the car is not fully warmed up, I get no, or next to no detonation, I have noticed that my intake temps are also cooler. Just some food for thought. Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted July 2, 2012 Share Posted July 2, 2012 What is your a/f ratio?It will ping if it is lean.Have all of your injectors been flow tested? Quote Link to comment Share on other sites More sharing options...
Gollum Posted July 3, 2012 Share Posted July 3, 2012 (edited) Yea this is weird results if you ask me. I'd be looking very closely for something else going on. First thing first I'd do a long full throttle run and shut the engine off and check the plugs. Considering how many people have run 10psi+ on 91 and less octane with NO intercooler on the STOCK ecu with no extra timing being pulled... I'd say there's something else going on here. But that's just my hunch. Thank you for the data though. It's always helpful. Edited July 3, 2012 by Gollum Quote Link to comment Share on other sites More sharing options...
letitsnow Posted July 3, 2012 Share Posted July 3, 2012 How are you detecting detonation? Det cans? Quote Link to comment Share on other sites More sharing options...
Datsun Deron Posted July 3, 2012 Author Share Posted July 3, 2012 Randy - my air fuel ratios are 11.5-11.7. The injectors have not been flow tested. Gollum - ill check the plugs when I get a chance Letitsnow - I could hear the ping by ear driving the car. Then we pulled the timing back 2-3 degrees for a safety margin I'm honestly surprised to see much concern regarding my results. From what I've read regarding my configuration I thought my results are pretty standard. Keep in mind I'm running non turbo flat tops and a p90 head. This setup brings my compression ratio way up around the 9:1 mark instead of the low factory compression at 7.4:1. Should I be able to pull more timing? I thought most people shy'd away from this setup for that very problem. Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted July 3, 2012 Share Posted July 3, 2012 I'm actually just about to try this using the factory parts. I have a p90 head with forged flattops, and I bought all the stuff to convert to a stock turbo setup, just got my exhaust manifold back from coating. Need to send my injectors off to get cleaned then I can start putting everything together. If you say it lived happily at 7psi for a few years then that gives me hope. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted July 3, 2012 Share Posted July 3, 2012 I'm surprised because with 7.4:1 I needed to be around 25-27 deg at peak tq, almost 40 near peak power, to get audible detonation(the dizzy walked on me once). Thinking about it, 14 at peak tq doesn't sound that far off, I bet you can add significant timing after peak tq and pick up some upper end power. Quote Link to comment Share on other sites More sharing options...
Datsun Deron Posted July 3, 2012 Author Share Posted July 3, 2012 @ BluDestiny - The engine pulls great with flat tops and turbo. I've been really happy with my setup. I originally did a non turbo build, then converted to MS, then wanted to turbo but was too cheap to pay and have another bottom end rebuilt. I figured I'd run her and see what happens, so far so good. If I did another turbo L28 build I'd still likely shoot for either a stock compression ratio or closer to 8:1 maybe. Good luck with the build! If you need to steal any timing or fuel maps just let me know and I can send it your way. @ letitsnow - That sounds about right from what I saw on the tuning/map sharing post on hybridz. The stock turbo motor is a completely different animal from this configuration. Quote Link to comment Share on other sites More sharing options...
Gollum Posted July 3, 2012 Share Posted July 3, 2012 (edited) This setup brings my compression ratio way up around the 9:1 mark instead of the low factory compression at 7.4:1 Really now? Because by all accounts with a OEM gasket you'd be at 8.3:1 compression, just a .9 jump from 7.4, not the 1.6 jump you're saying your motor is. Are you running an ultra thin HG? The stock turbo motor is a completely different animal from this configuration. This is certainly true. I'm sorry if I seemed rude at all previously. It's just that timing info for various setups is surprisingly hard to come by for hard facts. I know the flat top P90 combo will REQUIRE less timing, which is different than WITHSTANDING less timing. What troubles me isn't that you could only run 14 degrees at 10 psi, it's that you had detonation with 94 octane which I don't believe should really have been the case. What I'd LOVE, is for you to get some 110 in there and play with the map to see where peak power really shows up when detonation isn't on the table. The danger I see with this setup is that people don't realize how much less timing they'll NEED with the extra quench the flat tops provide and just assume they'll back a few degrees off using the stock dizzy. I've always maintained that to do this setup right you need programmable fuel and spark, and it makes me quite happy that's what you're doing and sharing info with us. Edited July 3, 2012 by Gollum Quote Link to comment Share on other sites More sharing options...
Pyro Posted July 3, 2012 Share Posted July 3, 2012 Seems about the same as we got when I helped a friend install a turbo on a 81-83 flat top L28 engine. Took only 17 degrees of timing with 8 psi of boost and 93 octane. Quote Link to comment Share on other sites More sharing options...
dexter72 Posted July 3, 2012 Share Posted July 3, 2012 (edited) Seems similar to mine as well, I can get a couple of more degrees of timing though. You can run timing in the 40's in your lower KPA RPM Bins. My next thought is your Kpa scale looks low to me, Maybe try increasing the scale into the 200 kpa range. It won't read high enough for a larger turbo upgrade. Have you closed up the spark plug gaps yet?. I did that and it helped my earlier pinging issue out greatly. I would also think about going to the next colder range spark plug. 10 psi on a stock t3 turbo is about the max it will work at efficiently, you may need to upgrade the turbo if you want more power. I have t3/t4 turbo and am running 15 psi of boost. Its a blast. I have a 89 Supra turbo intercooler on my car and placed the air filter in front of the intercooler. I don't know if it helps with the pinging or not. I am just a believer in having the air filter outside of engine compartment heat and in a fresh air stream. My intake air temp sensor is placed as close to the intercooler as I could put it. It was in the intake manifold and the temp difference read 70 degrees cooler, just by moving it out of the intake manifold. Try those things and see if it helps. I live in Phoenix so our high temps are going to be way different this time of year then yours are. It was 112 here 2 days ago. But I normally drive my car 3-4 days a week up to about 95 degrees outside temps, then I drive my other car with a/c. lol Edited July 3, 2012 by dexter72 Quote Link to comment Share on other sites More sharing options...
letitsnow Posted July 3, 2012 Share Posted July 3, 2012 Getting on a dyno or to the drag strip is really the only way to determine what's going on. If the combustion chamber with the flat tops is much more efficient, you'll need less timing to make the same power. Who cares if you can only run 14-20 if you're making just as much power as I am at 25-30. Quote Link to comment Share on other sites More sharing options...
roger280zx Posted July 3, 2012 Share Posted July 3, 2012 (edited) Flat top p90 is about 8.8:1 compression with stock head gasket. Judging by the picture you really should move the intercooler back. Like, all the way against the radiatior back. With the intercooler way out front you are creating eddys behind it that keep BOTH the intercooler and radiator hotter. Less turbulence=more airflow. This will have much greater affect on the air temp than the location of the air filter. Edited July 3, 2012 by roger280zx Quote Link to comment Share on other sites More sharing options...
Gollum Posted July 4, 2012 Share Posted July 4, 2012 Roger, do you have definite chamber volume data I'm unaware of? By all accounts the P90 chamber is identical to the P79 and Nissan rated the compression of that motor (flat tops with P79) at 8.3:1. Now, most chamber volume measurements indicate Nissan might have underrated the compression by maybe .1:1, but not much more than that. I've seen plenty of bad info out there and because of that I tend to er on the side of Nissan's claims before what people say on the internet. Quote Link to comment Share on other sites More sharing options...
Pyro Posted July 4, 2012 Share Posted July 4, 2012 FYI, Nissan rated the 75 to 80 L28 as 8.3:1 (N42 block with dished pistons and N42 or N47 head). Then 8.8:1 in 81 to 83 with the F54 block with flat tops and a P79 head. 7.4:1 for the turbo with a F54 block with dished pistons and the P90 head. Yes, the P79 and 90 have the same size chambers. Quote Link to comment Share on other sites More sharing options...
Datsun Deron Posted July 4, 2012 Author Share Posted July 4, 2012 @ Gollum - You didn't come across rude at all. I'd be very curious to see what would happen with 110 octane as well. @ Dexter - Thanks for the heads up on the lower bins. I noticed the stock turbo guys were running in the 40's and made it a little conservative just incase. I'll be sure to adjust those next time im tuning. As for weather here we do get some pretty hot days through July to September ranging anywhere from 86 to 104 degrees (when we get the real heat waves). I haven't tried closing the spark plug gaps yet, and I am currently running NGK plugs (two steps colder). We had some detonation issues when I first did the swap. Would two steps colder be too cold? I could possibly run 1-2 degrees more timing but pulled it back for the added insurance. @ roger280zx - I had originally tilted the intercooler so more of it was being hit by the opening in the air dam. Ideally though straight up and down, further back with some ducting would be the ideal way to go. I've actually been very curious to calculate the efficiency of the intercooler with the way its currently laid out. I should get on that. I might also look at ducting in the near future. @ pyro - Thanks for confirming the 8.8:1. My very scientific calculations came from information from this forum or zar.com. Quote Link to comment Share on other sites More sharing options...
aarang Posted July 4, 2012 Share Posted July 4, 2012 What cam are you running? I have been running my flat top P90 turbo for 5 years now with great results on the stock ZXT EFI. Granted, not much is stock accept for the bottom end, but I think cam selection for the higher comp makes a difference. I have a mild Delta Cams turbo regrind. If you don't have it already, you may want to consider at least the 'A' cam. Aaron Quote Link to comment Share on other sites More sharing options...
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