SleeperZ Posted August 10, 2011 Share Posted August 10, 2011 Got the head off just now. No damage to pistons or any of the valves. Hopefully I can have it together tonight with new chain, tensioner, and guides. Time to find another boost controller and hit the dyno again. Are you sure there is no valve damage? It would really suck to have a valve drop off its stem because it mushroomed on contact with the piston and wasn't replaced. Quote Link to comment Share on other sites More sharing options...
itzgoten Posted August 12, 2011 Share Posted August 12, 2011 itzgoten, you ever take your car to the drag strip? Mr JDM, I don't drag only take it to the track (road race). I was out there and spun a bearing after the build so now I'm back at square one. I'll probably take it to the drag one day just to see what kind of numbers I run. Quote Link to comment Share on other sites More sharing options...
itzgoten Posted August 12, 2011 Share Posted August 12, 2011 Got the head off just now. No damage to pistons or any of the valves. Hopefully I can have it together tonight with new chain, tensioner, and guides. Time to find another boost controller and hit the dyno again. Are you sure there is no valve damage? It would really suck to have a valve drop off its stem because it mushroomed on contact with the piston and wasn't replaced. I'm surprised.. Kind of agree with SleeperZ.. Sounds too good to be true. I would just say take any precautions you can to make sure you're 100% sure. If that is the case though.. you're one luck guy. Quote Link to comment Share on other sites More sharing options...
mr jdm Posted August 12, 2011 Author Share Posted August 12, 2011 I was a little bit shocked too, I will have the car together tonight and do a compression test before I try to crank it over. There isn't a single mark on any piston and no marks on any of the valves. I dont feel like taking the valves out to check them, I will only do that if my compression numbers aren't good. Quote Link to comment Share on other sites More sharing options...
itzgoten Posted August 13, 2011 Share Posted August 13, 2011 I was a little bit shocked too, I will have the car together tonight and do a compression test before I try to crank it over. There isn't a single mark on any piston and no marks on any of the valves. I dont feel like taking the valves out to check them, I will only do that if my compression numbers aren't good. Which is completely logical to me. Let me know how it goes! Quote Link to comment Share on other sites More sharing options...
mr jdm Posted August 14, 2011 Author Share Posted August 14, 2011 I worked on it for a little yesterday but ran out of time. The car will be running within the next 7 days. Today I found what caused my chain to snap. If you are fimiliar with KA or SR motors, then you know most people remove the upper timing chain guide, I did that. But I have a habbit of putting bolts into the threaded holes they came out of, bad idea! I both bolts threaded where the guide was after it was removed, turns out one bolt backed out and fell, this bolt fell between the chain and crank sprocket. That has to be why it snapped, and it explains the beat up bolt that was at the bottom of my pan. Quote Link to comment Share on other sites More sharing options...
Gollum Posted August 15, 2011 Share Posted August 15, 2011 I'll back Pyro's pressure ratio power calculations. Yes they're "just calculations" that might not be 100% accurate all the time, but Corky Bell and others who've written reliable books give out the same numbers for HP per PSI gain. The ONLY reason one turbo might make LESS or MORE HP at a given PSI on identical engines than a different turbo, is because of EFFICIENCY which directly relates to TEMPERATURE. You can also calculate how much temp increase you'll get per PSI to help the calculations stay accurate. Obviously if you're adding water/meth injection then this further skews the math estimates, or you can view it simply as another factor that needs to have it's variable calculated. As to our example here, I've seen NA SR's make a heck of a lot more than 150whp on a stock motor with nothing but an experienced tuner who knows what they're doing. With how well the SR head flows, being a 2 liter I'd EXPECT it to be able to reach 170 wheel HP if it's optimized for premium, which you're normally doing when you're tuning a turbo'ed motor. All I'm getting to is that yes it's just a calculated guess, but the more dyno data you have at given PSI's the more you can predict where you'll be when you up the boost, and some tuners will actually use MATH (oh my, really?) to setup tables ahead of time to best guess how much extra fuel will be needed at elevated PSI levels. They don't just throw up numbers and hope it's right. They calculate it based on previous data. And if you DO know how much power a motor made at 1.5 pressure ratio, and then again at 2.0, you can make a crude graph to predict what will happen all the way up to 3.0 pressure ratio, then you just need adjustment factors for your setup, like what turbo you're running. Quote Link to comment Share on other sites More sharing options...
mr jdm Posted August 15, 2011 Author Share Posted August 15, 2011 (edited) If you think a good tuner will predict how much fuel to add, instead of tuning 2 psi increments on the dyno, then your tuner is somebody I would rather not bring my car too. Edited August 15, 2011 by mr jdm Quote Link to comment Share on other sites More sharing options...
mr jdm Posted August 15, 2011 Author Share Posted August 15, 2011 (edited) I think next time I hit the dyno I will do an all motor pull to show how accurate this calculator is. Edited August 15, 2011 by mr jdm Quote Link to comment Share on other sites More sharing options...
Gollum Posted August 15, 2011 Share Posted August 15, 2011 If you think a good tuner will predict how much fuel to add, instead of tuning 2 psi increments on the dyno, then your tuner is somebody I would rather not bring my car too. Whoever said that tuners don't CALCULATE for those two psi increments? Professional tuners don't do their job seat of their pants. They do it with careful calculation to get predicted results. ANY quality tuner will be intrigued by an expected result, and will usually have a nagging curiousness to find out what caused it, BECAUSE they know that it's something meaningful when results aren't where they were predicted to be. I've seen tuners pour over engines for days simply because it make 3% more power than expected. I've seen tuners that took a brand new build that's never even been RUN build a base map all the way up to 20psi that was closer to on the dot than many people's street cars they're driving around every day, and yet they still did their first pulls after break in at 5psi, polishing off those cells, then moving on from there in small increments. The point I'm showing is that they CALCULATED the power the engine would create ahead of time, and that got them close enough to not blow up the motor. There's a reason the best tuners are some of the most anal people in the world. Quote Link to comment Share on other sites More sharing options...
Gollum Posted August 15, 2011 Share Posted August 15, 2011 I think next time I hit the dyno I will do an all motor pull to show how accurate this calculator is. I also never said that a NA SR should make 190+HP. You're also assuming I agree that the basic calculation Pyro gave is what I'm talking about when I say tuners CALCULATE things. You can take a predicted volumetric curve based on previous data from similar engines and graph out how your cam(s) will interact with your predicted head flow. Then you can take a given RPM, and with the data on hand you'll know how much airflow there will be at ANY PSI, thus about approximated how much fuel will be needed at THAT point with THAT much PSI. You can then run the numbers slightly rich and retard the timing accordingly for what TEMP you think the air will be at. Air is air, and it's easily calculated when you know the volumetric efficiency of an engine. You can't always calculate a winning tune, but you can get in the ballpark which is a heck of a lot better than guessing. Here's an example: I know a B16 is damn near 95% volumetric efficient at peak torque, which occurs usually just after vtec kicks in, and let's say that's happening at 4500. So I now know that at 4500RPM, this 1.6 liter is pushing roughly 120 CFM of air per minute. So now let's shoot for a 12.5:1 air fuel ratio guesstimate. 1 CFM = .0745 LBS/Min. So we have 8.94 pounds per minute of air. In order to keep the math easy we'll work with the lb rating for inejectors, because we're adding fuel based on WEIGHT, not volume. Injector's weight rating though is lbs per hour. So we take our 8.94lbs per minute and x 60 for our hour rating. 536.4 lbs per hour. So divide that by our target 12.5:1 and we get 42.912. Of course we have four injectors sharing this load so our target is 10.728lbs per hour. So IF we were running a 20lb injector on our B16 a 54% duty cycle would calculate to 10.8 pounds per minute, just over our target and acceptable by my standards for a rough tune. Now again, I feel like I need to emphasis something that rarely seems to get understood by people. Even if one turbo might "flow less" at a given psi doesn't change physics. 20psi will always be 20psi, IF TEMPS ARE EQUAL. The reason the turbos that flow less at a given PSI don't make as much power has to do with AIR TEMPS, NOT some magical turbo factor. It's all basic physics. If you take a given volume of air and create pressure, but then lower the temperature of said air than the pressure will drop WITH the temperature. This is why compressor maps are so important, because they tell you the efficiency and how much heat to expect to be adding into the air charge, thus increasing psi without respective flow. So, IF we know an engine's NA requirements like the B16 above. And we know the turbo on the engine's efficiency is fairly well matched for the air flow and RPM range of the motor, then we can calculate the fuel requirements quite accurately. Another factor that should be mentioned, and I think this comes into play with the SR20 we're talking about in this thread, is that most motors never make it to atmospheric during a dyno, and thus we can't calculate power gains based on 14.7psi being atmospheric. This is probably why the "basic" calculations show this SR should be making 190hp. Doing a slight factor adjustment, assuming NA was only reaching 13.7 psi then @ 18 psi it was actually under a 2.39 pressure ratio, meaning under a full atmospheric 14.7 it should reach 179, which seems in the ballpark because when I calculate that to 13.7 psi it's 166. And IF your dyno was reading just a touch high, couldn't that be correct? I didn't fudge numbers to make it match what you said, I used my logical experience of using math to predict what's happening. But based upon MY eductated guess, I'd say that on that dyno with the turbo bypassed you're probably going to put down 166hp if you optimize your fuel and timing for the same RPM range as you ran before. (7k I think right?) If you want to get into finding out more about how temps will affect your flow at a given PSI, this is a good book to start with and covers a lot of basics that get overlooked by most amateur tuners. http://www.amazon.com/Modify-Management-Systems-Motorbooks-Workshop/dp/0760315825 Quote Link to comment Share on other sites More sharing options...
(goldfish) Posted August 18, 2011 Share Posted August 18, 2011 It's a wack calculator. PSI itself has not much to do with power levels. All things a side, 14.7 psi on a gt25r compared to 14.7 psi on a gt35r, not the same power. Psi doesn't matter, flow does. Let's keep this discussion in context. We are talking about different boost levels on the same configuration. and it's a quick, dirty, rough calculation to get you in the ballpark. Quote Link to comment Share on other sites More sharing options...
mr jdm Posted August 19, 2011 Author Share Posted August 19, 2011 Got the motor together today, had it comp tested, everything was 150 except cylinder 2 was 0. Back to the drawing board. Quote Link to comment Share on other sites More sharing options...
mr jdm Posted August 19, 2011 Author Share Posted August 19, 2011 Whats even worse, is I'm not entirely sure if its the vales or the piston. Reason is , is about 6 weeks ago I swapped in a new crank, piston, and rod due to my oil pickup cracking and losing pressure while doing a high speed run. I installed those parts and everything worked great, and had comp tested 150 across before I was at the dyno, car made great numbers on the dyno. I still dont know whether to think the valves got fucked up or if that piston/ring I installed went bad, anybody have suggestions besides doing a leakdown test? Quote Link to comment Share on other sites More sharing options...
Gollum Posted August 19, 2011 Share Posted August 19, 2011 I have a hard time imagining that it's a piston ring issue. Reason being is that I've seen compression tests on a few bad motors, some with severe ring land breakage, and not a single one of them compression tested all the way down to zero. Even with bad rings there's very little opening area for compressing air to escape through, while a valve that's not sealing just a mere .010" will have substantially more area for air to get through. So my logic says look at the head first, then the bottom end. Maybe I'm just an optimist. Quote Link to comment Share on other sites More sharing options...
mr jdm Posted August 19, 2011 Author Share Posted August 19, 2011 I am so pissed, tomorrow I will pull the motor put it on the stand and takes thing a little bit slower. hopefully I can have time to pull the valves. I remember an old trick back in highschool that I learned, it was something like putting grease on the valve, and then holding it up and spinning it, if it left a perfect circle it was good, and if it didnt it was bad. Anybody know the exact details to this method, or I have done a lot of engine work before, but I have never really dealt with bad/bent valves. Any suggestions how to inspect them if they arent completely obvious? Quote Link to comment Share on other sites More sharing options...
itzgoten Posted August 20, 2011 Share Posted August 20, 2011 (edited) Bah! Go figure.. I was assuming it was going to be a bent valve. I honestly felt like that was going to happen since the chain broke. I wouldn't have the know-how or balls to take on a job like that on my own. I'd just replace the valves and have the machine shop do the work. Keep us posted man. I really hope your car is back on the road soon. Would be a crime for such a great car to be hidden away in a garage. Edited August 20, 2011 by itzgoten Quote Link to comment Share on other sites More sharing options...
mr jdm Posted August 20, 2011 Author Share Posted August 20, 2011 Well, I am back on being confident that I dont have bent valves. I pulled the motor earlier today and just took it apart (except the head is still on the block) I made such a bad mistake, in the last few weeks I have had the head off the motor about 3 times. None of those 3 times I tightened my arp studs, not the NUT, but the actual hex key on top of the stud.I only tightened them about 2 years ago when I first was assembling the motor. Anyways, today when I was unbolting the nuts to the head studs, cylinder number 2, intake side, the nut came out with the stud! On top of that, when I unbolted my oil pans, I had brand new fresh oil with some slightly mixed coolant. I'm pretty sure 0 compression was due to the head stud, however, tomorrow I will lift my head off and head to a napa machine shop and have them pressurize and vaccuum test my valves anyway! results posted shortly Quote Link to comment Share on other sites More sharing options...
itzgoten Posted August 20, 2011 Share Posted August 20, 2011 AHH! That sounds way better than broken parts. There is always light at the end of the tunnel! Quote Link to comment Share on other sites More sharing options...
mr jdm Posted August 24, 2011 Author Share Posted August 24, 2011 Not that lucky, leakdown test confirms there is a problem on the intake valves Quote Link to comment Share on other sites More sharing options...
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