speeder Posted December 31, 2003 Share Posted December 31, 2003 I couldn't find the previous post where I promised to give results of my moving the cam timing from one hole advanced (2 on the sprocket) to straight up (Hole 1).- so here it is. I had hoped that EGTs would go down as a result of the theoretically reduced clinder pressure. They did, but not as much as I had expected - only about 50* at 18 psi boost. I did gain a noticable increase in power, both by the butt dyno and by cutting about 1/2 second off the time to wind out 3rd gear, as measured by my datalogger. So here's the story: I had advanced the cam in hopes of improving spoolup and getting some extra bottom end, and it was counterproductive. I may try retarding the cam slightly with my Nissan Motorsports sprocket to see what happens, but that's for later. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 31, 2003 Share Posted December 31, 2003 wow... so it really makes a big difference with top end pull huh? I think mine is on the #2... The reduced cylinder pressure should also mean less chance of detonation right? Sounds like a good deal... too bad I wont be getting back to the dyno soon, I'd like to see what this one trick alone yields. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted December 31, 2003 Share Posted December 31, 2003 I figured that th ecylinder pressure increase as the cam timing advance. I really need to check up on that. How high is your EGT anyway? Quote Link to comment Share on other sites More sharing options...
speeder Posted December 31, 2003 Author Share Posted December 31, 2003 Since I've had the EGT gauge, I've been alarmed with how high the temps have been with this setup. 1640* at 18psi makes a real concern for the stock bottom end. Also, it has been interesting to watch EGT at cruise - at 1450* on 5th gear 80MPH cruise I began to worry. Those who have been entertained by my previous destruction of pistons will understand this concern. So far , my freshened up stock ZXT engine has taken a lot of abuse - but I really am impatient to get the new forged piston stroker on -line. I've just refined my E-motive tuning so that I have a flat 11.8 : 1 AFR under boost as measured on the wideband, have advanced timing about as much as I dare (24* on boost with no detonation, running 20% toluene) and now EGT is peaking just under 1600* this is with the new cam timing. I'm starting to feel good about tuning now. Quote Link to comment Share on other sites More sharing options...
speeder Posted December 31, 2003 Author Share Posted December 31, 2003 Bastaad, Top-end pull definitely improved by retarding the cam. Interesting to note that the old rule of thumb about gaining some low end by advancing the cam didn't apply to my setup. I think that the turbo actually spools faster with the cam retaded to straight up! Of course no two of our cars are the same - And, I do believe that detonation resistance is improved with the lower EGTs. Quote Link to comment Share on other sites More sharing options...
Guest ZmeFly Posted December 31, 2003 Share Posted December 31, 2003 That was my post your referring to about retarding the cam to get more out of the car ie because of the theoretical cylinder pressure decrease. I found and thought about that in dealing with NA's. So top end was better and how was or did over all driveability or low end power change any? Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted January 2, 2004 Share Posted January 2, 2004 Your temp while at 80 MPH sounds alittle high to me. I'm running about 1300 to 1350 at the same MPH. Isn't toluene fun. I can run 17 psi on the 93 octane we get here but, with a 30% toluene ratio added I can run well over 20 PSI. I raced a very hot LT1 Trans-Am one night on the way home from the track and I held over 20psi (gauge only goes to 20) and who knows how much EGT long enough to show the the LT1 guy who was boss and had no proublems. I pulled 5700 RPM's in 5th gear so I was at full load on the engine as well. Needless to say it was because of the higher octane octane of the fuel. Quote Link to comment Share on other sites More sharing options...
jgkurz Posted January 2, 2004 Share Posted January 2, 2004 After reading this post I think I'll try adjusting my cam timing for some improved power. If I remember correctly there are two types of adjustable timing sprockets for the L series Datsuns. The NISMO type p/n 13024-E4621 and the HKS type that doesn't require the chain to be removed. I'd prefer to buy the HKS type if possible. Does anyone have a recommended source? Thanks Quote Link to comment Share on other sites More sharing options...
yo2001 Posted January 2, 2004 Share Posted January 2, 2004 Your temp while at 80 MPH sounds alittle high to me. I'm running about 1300 to 1350 at the same MPH. . I was going to say that. Mine cruise 80mph, 3600rpm at 1350-1400 or so. Quote Link to comment Share on other sites More sharing options...
Guest ZmeFly Posted January 2, 2004 Share Posted January 2, 2004 Toluene that is for a LONG while, but when I go to the local paint stores, must be going to the wrong ones they look at me like Im nuts when I ask if the carry toluene. Where do you buy it from and what mix do you use Cody? Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 2, 2004 Share Posted January 2, 2004 Last time I checked, Home Depot had Toluene, it was either $5 or $10 a gallon I forget. You can also try looking for Xylene, which is very similar stuff. I'm kinda confused on toluene though, I understand it raises the octane and all and can deter detonation, but I thought that it would NOT stop detonation caused from just plain high temperatures? I say this because I had asked before if simply adding toluene would allow me to run higher boost safely on my non-intercooled setup, and I was told that though it would richen the octane and allow me to get away with a leaner mixture (caused by more air from the turbo) it would NOT prevent detonation from the heat. Guess I'm not too confused as this makes sense to me now that I read it back... so do I have that right? By the way, all the hod rodders that I chatted with that mentioned toluene to me for this purpose were recommending a 10% solution of the stuff, which works out almost perfectly to one gallon can per one full tank of fuel. This is supposed to be good for about a full three point increase in octane, so for my crappy socal gas, from 91 to 94 octane. I really want to do a before and after dyno using this stuff. Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted January 2, 2004 Share Posted January 2, 2004 Just run a couple gallons of 110 leaded in there. I can run 19 to 20 psi with regular unleaded here, but with 110 leaded mixed in there, who knows. I think we have 112 or 114 out here at the track, I am going to have to try some of that very soon. Oh and you get your egts out of whack and it doesn't matter what kind piston you have, aluminum still melts at the same temp, be it cast or forged. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted January 3, 2004 Share Posted January 3, 2004 I got my Toluene from a friend who owns a paint store. I got the 30% ratio from a web site that I can't remeber. Seemed like it worked good for me. I can't say I would want to just cruise around town all the time with it but, it sure made for a fun ride home. I had a could of gallons of the "the mix" left for a day or two and it made for some quick passes on the highway and some fun on the onramp if you know what I mean. I was just dying for someone to challange me but, ofcourse no one did. As I understand it (please correct me if I'm wrong here) the higher the octane the slower the burn rate of the fuel. Theres really much more to it but, that is the point were talking about here. Specific fuel can be made to benifit a certain engine caracteristics (sp) It's like retarding the timing without any of the side effects. Some of those side effects are lower power and higher EGT's. I'm sure if you had a good air fuel ratio and some time to tune the car with the higher octane fuel in it some real power could be made. You still have to have a correct A/F ratio but, it helps if the tuning it not exact. Like anything you just have to do some experimenting with it and be ready to get off the gas and be man enough to accept it if you stayed in it to long and tore something up. This coming spring I'm going to have some good tires hopefully, when I go to the track. I've never had any real race tire or even good street tires so who knows what the car could do. The toluene is cheaper than race gas for me and seems to work good. I'm going to take my time and see what I can get out of the car with the higher octane. I'd like to be in the range of Lockjaws time slips but, I think that still a ways away for my ZX. If the EGT gauge wraps around to "the other side" is that bad? J/k Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted January 3, 2004 Share Posted January 3, 2004 Oh and you get your egts out of whack and it doesn't matter what kind piston you have' date=' aluminum still melts at the same temp, be it cast or forged.[/quote'] Just curious anybody know what that # is? And for how long it would have to be subjected to that temp. What about valves etc....... Quote Link to comment Share on other sites More sharing options...
yo2001 Posted January 3, 2004 Share Posted January 3, 2004 anything over 1620 coming out of the EGT isn't going to be good I was told. Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted January 4, 2004 Share Posted January 4, 2004 I was thinking aluminum melts at 1200 degree's, but I could be mistaken. I am sure someone can google it and tell us. Either way, get it to hot, and it doesn't matter what it is, its melting. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted January 5, 2004 Share Posted January 5, 2004 Well the piston doesn't take all the heat until you detonate. That's my understanding. As long as EGT stay up, the pistons are staying cooler, when your EGT drives down under WOT, the heat is being transfer to internals like valves and pistons Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted January 5, 2004 Share Posted January 5, 2004 Detonation puts holes in it, like it has been sandblasted, and in worse cases, breaks things. Quote Link to comment Share on other sites More sharing options...
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