TimZ Posted December 14, 2005 Share Posted December 14, 2005 It should be lower since he is running slightly higher compression ratio then me so not exactly comparing apples to apples but close. Well, not so much. The increased efficiency of the higher cr means that more heat is converted to work in the power stroke, so the exhaust temp should be lower, all else equal. This will result in less expansion at the exhaust, and higher spool. Quote Link to comment Share on other sites More sharing options...
Thumper Posted December 14, 2005 Author Share Posted December 14, 2005 Well, not so much. The increased efficiency of the higher cr means that more heat is converted to work in the power stroke, so the exhaust temp should be lower, all else equal. This will result in less expansion at the exhaust, and higher spool. Your right that the temps will be lower so there will be less volume. But since he has a higher compression ratio it will compress the air more increasing its velocity when the valves open. So I think the higher velocity will overcome the neglible decrease in egt's especially at lower rpms. This line of debate would not be off topic if I had asked what can I do for less turbo lag or what causes turbo lag, but I asked how can I TUNE for less turbo lag. And in my first post I clearly described my question as tune as in timing and fuel settings. Thanks for your input though I have learned alittle more about turbos but I felt the topic was becoming more of a debate than an answer to my question. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted December 14, 2005 Share Posted December 14, 2005 ted, IM me that link about the alternator when you get a chance, the one i have doesn't cover wiring on the 73's alternator/vr plug, didn't even mention anything about a diode or resistor, so i probally have the wrong link saved... gonna see if i can get my headlights wired up real quick and go for a spin. Quote Link to comment Share on other sites More sharing options...
260DET Posted December 15, 2005 Share Posted December 15, 2005 Tried adjusting the amount of fuel on over run Thumper? That and a capable BOV have a lot to do with not loosing spool between gearshifts. BB turbo of course, a modern one like the Garrett GT-R series which have improved aerodynamics as well. Is the Holset as good? Correctly sized, goes without saying. Don't know about special tweeks but with a good setup including a capable, properly tuned ECU you should pretty well be there. Quote Link to comment Share on other sites More sharing options...
TimZ Posted December 15, 2005 Share Posted December 15, 2005 Your right that the temps will be lower so there will be less volume. But since he has a higher compression ratio it will compress the air more increasing its velocity when the valves open. So I think the higher velocity will overcome the neglible decrease in egt's especially at lower rpms. Sorry to keep going "off topic" but I don't think this is right - the exhaust valve opens well before bottom dead center, so there should be no appreciable difference in the exhaust velocity on the exhaust stroke on the higher cr motor, unless the cam profile is radically different. This line of debate would not be off topic if I had asked what can I do for less turbo lag or what causes turbo lag, but I asked how can I TUNE for less turbo lag. And in my first post I clearly described my question as tune as in timing and fuel settings. Thanks for your input though I have learned alittle more about turbos but I felt the topic was becoming more of a debate than an answer to my question. Yes, it did turn into a bit of a debate, but the debate still centered around what is effective and what is not regarding changing the turbo spool, and what trade-offs you might be making to acheive the change. This knowlege is key to understanding how to tune for the effect you were looking for. The most reasonable advice that I saw was to tune for maximum power in the boost transition region, rather than trying to change where the turbo spools. This way you will get through the transition region sooner, and it will feel like less lag. Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 15, 2005 Share Posted December 15, 2005 How much of an change do you suppose coating the piston, chamber, valves would help? From a stationary powerplant standpoint, I can answer that question, Moby. I had a wild hair and spent a bunch of money ceramic coating the exhaust elbows, exhaust port, combustion chamber of the head, including valve faces, and piston crown. The difference in wastegate position was ASTOUNDING! We ended up overspeeding the turbo past 24,000rpms using the stock 3" diameter wastegate, and had to upsize the unit to 4" to be able to control the turbocharger at the requsite 17,000 rpms to give us our 24psi in the intake manifold. Our gas consumption on the engine decreased by nearly 20,000 CF/Day---meaning to me, more heat was available to drive the turbine with less BTU's input. I forget the actual heat rate on the engine, but it was CONSIDERABLY lower than the other two units that were not treated to the ceramic coating treatment. Our exhaust temperatures usually ran in the 1100F range, and the cylinder to cylinder variation also was lower. So from that testing, I was sold on the benefits of the treatments. How this relates to mobile powerplants may not seem applicable, but you can see there was a decrease on fuel consumption, and that means more efficiency (or probably more aptly less loss!) Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted December 15, 2005 Share Posted December 15, 2005 I can chime in on the coatings aspect and provide some usefull info, not to hijack the thread. On my 400 cummins I have thermal coated pistons, ported heads, Series 4 Holset mapwidth enhanced turbo and a turbo boot which is an insulated boot that covers the exhaust housing. With the coated pistons alone I didn't notice much of a change, but I had turned up the fuel pressure from 170psi to 190psi and added bigger injectors, so EGT's stayed about the same. But when I added the turbo boot, I gained 3psi boost up to 30psi from 27psi, mind you stock boost for a 400 cummins is 24psi and the bigger turbo upped it to 27psi. EGT's plummeted from 800 deg down to 700 range during a hard pull with the turbo upgrade and dropped to 650 with the addition of the turbo boot. Mind you my EGT's are read directly after the turbo in the 90degree 5 inch downpipe. My exhaust splits after the downpipe and I run dual 5 inch exhausts through mufflers. Also with the addition of the turbo boot the boost doesn't fall off as much during shifts. Used to be that when I shifted the boost went to zero, now it hangs at 4psi and the turbo spools alot more rapidly and I don't have the black smoke rolling out of the exhaust when I shift. Fuel consumption went down. My mileage went up from 4.5 mpg to 4.8 mpg average. Simply amazing how much more HP and boost you make and how much better and more efficient it is retaining heat in the exhaust side. My Gale Banks twin turbo system has turbo boots for both turbo's and heat shields for the exhaust and turbo's themselves. I'm going to send the manifolds off and have them thermal barrier coated, as well as the downpipe too. The banks manual says the turbo boots enhance spool, maintains spool during shifts and increases boost. I'd like to play with that in a before and after comparison, so I'll try it without the boots and with when I get mine going. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted December 15, 2005 Share Posted December 15, 2005 So what you just said is that heat does make the turbo spool after all. Not quite. Well, yes and no. The energy is in the form of the heat but the turbo spooling is all mechanical. Meaning that it's the mechanical force of the gasses against the blades that cause it to spin. Quote Link to comment Share on other sites More sharing options...
zguy36 Posted December 16, 2005 Share Posted December 16, 2005 Whoa, it has been a while since I have taken a look at this forum. This post has some serious mud slinging going on! Lots of stuff that I want to address, but isn't valid for this post, so I will bite my tounge! I will make on comment on whoever called me a textbook engineer though. I have done most of my learning by experiementing on my Z, not through my textbooks. The textbooks provide supplement and support to what I have learned through practical experience. Back to topic at hand, or close to it. If you are concerned with building boost sooner, there are ways other than tuning as well. I am currently building a divided T4 flange with a dual scroll actuator. I haven't yet decided which turbo I am going to upgrade to, but that will come when my manifold is finished. My idea (nothing new and taken from many factory applications) is to build an actuated dual scroll setup. Using a dual entry turbo, shut off one side under low boost and open under full boost. I should have numbers for differences in spoolup in about six months. This should allow for a larger turbo to be used without as much increased lag time. It could also be used with a small turbo and have nearly zero lag time. I'll post some pics if you are interested. -jeremy- Quote Link to comment Share on other sites More sharing options...
zguy36 Posted December 16, 2005 Share Posted December 16, 2005 http://album.hybridz.org/showphoto.php?photo=5186&cat=500&page=1 Quote Link to comment Share on other sites More sharing options...
TimZ Posted December 16, 2005 Share Posted December 16, 2005 Hmmm - looks familiar... Quote Link to comment Share on other sites More sharing options...
zguy36 Posted December 16, 2005 Share Posted December 16, 2005 I actually found that picture searching this forum to see if anyone else had done this mod. I can't really tell what actuates the flap though. I can see that it is cable operated, but is it actuated at a certain boost level or at a certain throttle opening? I plan to open mine with a boost operated diaphram that opens the flap 2-3 psi before the wastegate opens. Is that setup on your engine, or did you just find the picture? I am interested in how much sooner the turbo gets to full boost and with what turbo. -jeremy- Quote Link to comment Share on other sites More sharing options...
Bernardd Posted December 16, 2005 Share Posted December 16, 2005 check turbomustangs.com, it's been done on there by someone. Quote Link to comment Share on other sites More sharing options...
Vintage-TechZ Posted December 16, 2005 Share Posted December 16, 2005 Hmmm - looks familiar... James.( Thagard)...if your out there?? DIdn't you build THAT particular "split Tangental" plate for one of your guys a few years ago ?? Seems like we had talked about this some time ago. I'm thinking it was used on the launch manually for 1/4 mile testing.....looking to improve their 0-60 ft. times. I don't recall any data from it though. You'd need some really sticky meats to get traction spooling hard THAT early. .............Vinny Quote Link to comment Share on other sites More sharing options...
Sean 83ZXT Posted December 16, 2005 Share Posted December 16, 2005 http://forums.hybridz.org/showthread.php?t=83566&page=2&pp=25 Scroll to post #42. Quote Link to comment Share on other sites More sharing options...
zguy36 Posted December 16, 2005 Share Posted December 16, 2005 Maybe I just missed it, but I didn't see the results of how the thing worked out. How much sooner did the boost come in? -jeremy- Quote Link to comment Share on other sites More sharing options...
Bernardd Posted December 17, 2005 Share Posted December 17, 2005 links to thread and results http://www.turbomustangs.com/smf/index.php?topic=45148.0 http://www.turbomustangs.com/smf/index.php?action=dlattach;topic=45148.0;attach=5732 http://www.turbomustangs.com/smf/index.php?action=dlattach;topic=45148.0;attach=5733 Quote Link to comment Share on other sites More sharing options...
TimZ Posted December 17, 2005 Share Posted December 17, 2005 Okay, now I'm afraid we really have hijacked this thread - I'll post an update in the thread that was linked above. Sorry about that. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 17, 2005 Share Posted December 17, 2005 Baastard- I had the same problem with my t3 when I ran it on my ghetto beast. It started when I put in the 370cc injectors and modified the afm. After doing lots of research and posting a question on hybridz I think it was timing. Since the afm was opening less the timing was different then if it was with a stock afm. I had an adjustable fpr and I raised it 10psi and lowered it 10psi with no effect on boost threshold or lag. I never played with timing since I was at the max I could with the amount of boost I wanted to run. I have now played alittle with my tuning and it seems that advancing the timing 2 degrees during non-boost and low-boost low-rpms areas have helped my spool time. I am running 39 degrees total timing now. I tried retarding the timing 5 degrees and there was a decrease in turbo response. A/f ratio I have not seen a big difference but I have kept it within 13:1-14:1 will spooling. I might try too give it more fuel or less fuel but as for now i'm happy. Any more input on the topic is greatly appreciated. Yeah I have definatley done a LOT of messing with the fuel mixtures via adjustable RRFPR and I haven't noticed any real change in the spool up speed. As far as timing related to AFM adjustment goes... that's one great upside of the RRFPR, I didn't have to TOUCH the AFM to run it... it only affects air/fuel ratios on boost, off boost it does nothing. I had toyed around with the AFM spring in the past but had marked it's original position and eventually just put it back to stock. I have actually advanced timing two degrees from stock, though I have no idea what its' doing at full boost/wot. I ended up going out of town over my weekend, left at the last minute to San Diego, so didn't get a chance to drive the Z and put that spring on the wastegate actuator as planned. Quote Link to comment Share on other sites More sharing options...
Thumper Posted December 17, 2005 Author Share Posted December 17, 2005 Hmmm and I was so sure it was because of when I adjusted the spring. Well for me the problem started when I upgraded to 370cc injectors. And went to 1g bov. I do know the 1g bov is designed to leak at idle so maybe just maybe right before it closes and holds boost the bov needs to have a certain boost present first like 2psi or so. And in lower gears it takes longer to meet that "threshold". But in higher gears because of more load and longer time in low rpms the threshold is lower. And same effect on lag the first second or to just gets blown out but once the turbo pushes enough at it then closes? I no longer have a 1g bov so i'm not sure if you want you can always just make a metal plate real quick and block the bov off and see if it helps. Quote Link to comment Share on other sites More sharing options...
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