bornagain280 Posted December 28, 2014 Share Posted December 28, 2014 I was looking at buying a master rebuild kit (pn 15403008) through zcar source. Kit looks like an overall complete kit, which I like, and also available in a standard bore (as long as my block checks out), or as close to it, without overboring. I know I'll be limited by the cast pistons, but I'm being mindful of my wallet. Im looking for 300-350 hp, I'm going to call zcar source and get some information from the particulars of this kit first hand(closed today), and see how far I can take the head gasket in their kit. I haven't had much luck finding a standard bore "mls" headgasket, which seems to be the best option, I'm trying to keep machining cost down by not punching the bore out, and not let the monster grow too big and put money in other areas. SDS, turbo, after-cooler So, guess I'm asking for head gasket options, opinions on durability, or sources that are as close to standard bore , but are mls gaskets. I'm wanting to buy the right part the first time.... thanks Chase. Quote Link to comment Share on other sites More sharing options...
chaos Posted December 29, 2014 Share Posted December 29, 2014 I just had a MLS done by cometic, took a week to make and ship to me so not bad. Looks great quality stuff, one down side is it being 240$. But I know to many guys that blew the HG from boosting too much. Another option if your looking for a normal thickness HG ( I wasn't got a 1.6mm) you van look into the rd site guess they are cheaper then they use to be and it's a great MLS. Quote Link to comment Share on other sites More sharing options...
TimZ Posted December 29, 2014 Share Posted December 29, 2014 But I know to many guys that blew the HG from boosting too much. You sure it was from "boosting too much"? More likely detonating too much, or just plain poor assembly practices. I've seen too many people that don't understand how to properly torque/re-torque a head, or even why you might need to. That said, I think maybe you guys are looking at this wrong. First off, a properly installed and properly torqued stock head gasket should not have problems in a properly fueled and tuned 350hp L-series. Second, the factory cast pistons can support 350hp, but they aren't very mistake-tolerant. At all. And guess what - they are mostly intolerant to the same kind of mistakes that cause blown head gaskets. So when you put that "blow proof" head gasket in there and make the inevitable mistake, you are likely to just end up with a bunch of broken ring lands. Yay. As big of a pain in the ass it is to change out a head gasket, it's still cheaper and easier than broken pistons. Quote Link to comment Share on other sites More sharing options...
bornagain280 Posted December 29, 2014 Author Share Posted December 29, 2014 This is the information I was wanting to figure out, and opinions are always good! I wasn't too crazy about $250-$400 HGs, and a lot of the MLS ones were 89mm that I saw and would require more machine work=more cash. I'm not building on a shoe string budget, but being cost effective and doing it right the first time. I don't see overboring to a 89mm really boosting my power numbers significantly in the money to additional power ratio, as long as an efficient turbo/aftercooler/engine management is used. Maybe I'm wrong? I follow what you're saying too Timz, there are guys that I work with that look at me crazy when rechecking torques after completing the initial torque sequence, and a lot of the time the first several in the sequence do require a little more torque after completion. Also when building and beefing up crane parts at work, I sometimes have to remind the higher ups that once one part is strengthened, the part next to it now becomes the weak link. So the cast pistons will be a variable in the equation, and is why I'll be happy with a good streetable 300-350 hp. I fully understand detonation is not a friend and want the fuel to "burn", not "explode". One of the reasons I did pick up a sds and plan on taking it to a local shop for dyno tuning. It has maps in it already, that made around 400 hp, 400 tq on another l28et that I bought from nelsonian here. I'm pretty sure that's a bit more than what my build would tolerate, so I need to be careful and most likely remap. I talked with zcar source, and the HG in this kit is a OEM comparable....so nothing special. I don't think I'm going to require a bullet proof $400 top of the line HG, but wanted to see what the next step up from stock would be. Another guy I know local recommended "cometic" also. Might be an option and Ill continue shopping around. Any more opinions are welcome, and experiences with particular brands....I guess a good question now is, are there any benefits to a MLS HG when running cast pistons? Would the head gasket supplied with the z car source master kit be acceptable when tuned correctly and achieve 350 hp?? Which is pretty much comparable to a stock composite. Chase Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 31, 2014 Share Posted December 31, 2014 (edited) I will agree with TimZ on this, I've run a stock Cherry Head Gasket on my L28 since 1985, set between 325-350 HP. You aren't "getting" the source of blown gaskets is detonation, not BMEP. Jeff P is running 475+ on his stock L28ET, with a standard FelPro head gasket...which I insisted he try because he's half deaf and driving a fully sound isolated S130, the only way he knows it's detonating is when the HG blows. Head gaskets don't blow from boost, they blow from detonation. Get your fuel and timing right and a stock Nissan L28ET or Fel Pro will be just fine as long as you aren't detonating. Jeff went through three head gaskets and one set of pistons before he got fueling correct. He conceded finally I was right: "run the stock bottom end because forged is just more expensive when it breaks." Get your tuning done to 350-400HP on stock stuff. By then you will know the fueling characteristics of the engine. As Jeff P found out it IS important to make a full rpm pass at "only" 8 psi. You need to determine power and torque peak. From that curve you can extrapolate fueling needs and potential as you raise the boost. The curve won't change, it will just move higher on the chart. First thing Jeff will do with his forged bottom end THIS TIME is make that pass at 8 psi first. Optimize it. Then calculate it out to see if everything is up to snuff before even trying higher HP runs. He's running to 7,400 now on cast pistons and hasn't found the power peak yet... But 475 at 7,200 at 17psi ain't bad on a stock L28ET bottom end with a FelPro head gasket, no? The power is in your head porting, cam, and turbo selection. Fueling properly prevents detonation and blown/broken things. You run an MLS on cast pistons, you just break them instead of blowing the head gasket when you detonate tuning the engine, and you WILL detonate. At 300 or even 350 HP, there is positively, absolutely no reason to piss money away on a piston breaking "seal all that pressure when you detonate" MLS head gasket! Edited December 31, 2014 by Tony D Quote Link to comment Share on other sites More sharing options...
z-ya Posted December 31, 2014 Share Posted December 31, 2014 (edited) I would just get the Felpro gasket kit. They have the best oil pan and cam cover gaskets, and their head gaskets are excellent too. I just ordered two from Advance Autoparts for the engines I am building this winter. I think they were around $60 each. Comes with all the seals too. Really good quality. For cast pistons, I've had good luck with ITM. Clevite bearings. You can get both 85 and 89mm bore Cometic gaskets, but I agree with Tony and Tim, stick with either stock OEM or Felpro head gaskets. FYI, I measured the hole size in the fresh Fepro gaskets I just received, and it's pretty darn close to 89mm. In an ideal world, you would want the head gasket hole size to be exactly the same as the bore. I've run 89mm gaskets on race engines with an 87mm bore without sealing or detonation issues. I use the MLS gaskets on race engines mainly because once the valves are unshrouded, you need a larger gasket hole so that the gasket has a sealing surface in the valve area. The only other reason to use MLS is if you need a gasket thicker than the stock 1.25mm size. Felpros are 1mm. Now that I know that the hole size on the Felpro gaskets are 89mm, I will setup the next NA race engine I build to use Felpro. I use a Felpro on my A12 race engine with 13.5:1 CR without issue. Edited December 31, 2014 by z-ya Quote Link to comment Share on other sites More sharing options...
bornagain280 Posted January 1, 2015 Author Share Posted January 1, 2015 (edited) I think you guys are solidifying my decision to run a standard head gasket over a mls, and keep some coin in my pocket. I definitely plan on taking the car to a dyno after I get it running and tune it before I take it out and have fun with it. The shop Im looking at agreed, the pistons are the next breakable part if the head gasket is blow proof, but did agree the stock pistons are pretty tough. He said he could help me get a few parts that I'm looking for, but I'm going to be careful, as I'm sure, I can source some of these parts myself. The whole 89 mm head gasket size is more clear too, since z ya mentioned extra spacing allowing one to unshroud the valves, which I was looking at doing, but waiting till I got my actual head gasket I'd be running, so an exact mark could be made. The soot mark is very defined where the factory head gasket is larger that the bore, but I'm not going to trust that when I start removing material. I've also seen ITM pistons around for sale, its just convenient to get most of the parts in one kit.....I wonder what manufacture supplies the pistons in the Z car source master kit. Don't need any Chinese crap, a lot of that Chinese imitation stuff out there now . I'm going to look around some more at the ITM pistons and see about piecing the rest together and see how I feel about it. I've gotta say too....475 on a stock bottom end has made me feel a lot better about the cast pistons too....sometimes reassurance from someone that has done it before helps. I would love to see his build specs on his engine. I know, I know, "search functions" ...lol. Kidding. Thank you guys a lot on this info., it makes me a lot more confidant that I'm going the right direction and don't need to throw thousands at a engine to get good results when proper built and tuned. Chase. Edited January 1, 2015 by bornagain280 Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 1, 2015 Share Posted January 1, 2015 Jeff used the ITM stock turbo pistons on his blown piston replacement. For their cost hard to beat! A note on sealing.... The diameter really doesn't matter, it will seal just as well at bore size as over sized 5mm, the fire ring effectively causes a super-high pressure clamping area which affects your sealing surface. The flat copper gaskets distribute that clamping force out quite a bit due to them being non compressible. They won't "creep" like a fire ring only clamped by the bolting forces...but that's more a function of how they are constructed. Same for MLS which have a very narrow fire ring backed up with a lot of metal to stop the fire ring from moving at all. O-rings are considered "blowout proof" simply because you machine a hole they fit into...when detonation occurs they move outward slightly in their groove similar to hydraulic o-rings, which then hits the shoulder of the groove, & can move no further. At this point bolt clamping forces are concentrated onto about a 0.040" wide sealing ring area resulting in extreme face pressures compared to conventional gaskets which may spread that clamping force over 0.080" or even 0.120"+ face! resulting in less face pressure....so the head gasket blows....let's combustion gases above face sealing pressure by....bang! The stock FelPro may have "X" face pressure, a wire O-Ring at the same head bolt torque may have 3 to 4X face clamping pressure...it still may move, but once backed by it's groove stops...it's either blow past that face pressure, or sink the rings on your piston! When you pull your head gasket, pay very close attention to, or hold it to a new gasket and look for the fire ring having moved. If it did, and your head/block is flat within spec: YOU ARE DETONATING! You may not hear it, and as I have said for a long time "the detonation you hear isn't breaking your parts, it's all those miles when you were detonating and NEVER HEARD IT! Anybody can lift when you hear that pinging. Everybody just stays in it if they don't hear it. Always check those gaskets during tear downs. JeffP's build with blown #5 cylinder showed similar deformation on 3/4. Going back through his dead gasket bid, he realized EVERY head gasket he had that was blown went on 5/6, or 3/4. This revalation in conjunction with talking to John Knepp of Electramotive and other experienced Datsun a Builders in heavy competition when currently a new model, pushed us towards the coolant-temperature detonation susceptibility realization. Quote Link to comment Share on other sites More sharing options...
bornagain280 Posted January 2, 2015 Author Share Posted January 2, 2015 I've rode 2 stroke dirt bikes for multiple years now and like turbo charging or any high performance engine I guess for that matter, you look out for detonation. I collapsed a ring land on a piston once in a rm 250, and all that I can figure is I mixed 87 with my race fuel instead of 93. Dropping my octane too low and causing detonation.... It was my fault, I got to runnin my mouth with someone at the gas station and grabbed the wrong pump. Luckily I did hear the engine pinging(easy when you're basicly riding it) and pulled it off the track, and saved the engine from blowing up. Never had any other pistons do that, so it had to be the fuel mixture, and that was a forged wiseco piston at that. I can understand the "detonating and not hearing it", with a loud exhaust and not much sound deadening in a s30. Very good information though, and I will do a full run and analysis at 8 psi when I go to tune this machine. I definitely don't want to toast any parts weather its a head gasket or piston. Learn to walk before I run so to speak. I think I also read another post that you mentioned coolant-temp detonation in regards to the size of aftercoolers blocking the radiators too much. Or at least higher coolant temperatures due to less airflow as a result of too large of a cooler. I'm not ready to buy a after cooler yet, but was researching optimal sizing. What is the most important variable when selecting one? I'm sure size has some to do with it, but potential flow due to inlet and outlet locations as well and overall construction design? I had a l28et built by sunbelt and I ran the largest spearco aftercooler I could cramp up front and looking back now, it was probably unnecessary and may have even been a issue. I never fully finished that car though to see its full potential. Im not in a race to build this engine, but pacing myself to make sure its sound and done right the first time and want to have fun and learn more while I do it. knowledge is power! As corny as it sounds. I Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 2, 2015 Share Posted January 2, 2015 Heat rejection capability. Look what size JeffP has on his 700+HP S130. During 5-Minute Oil Temperature Testing Runs where we held the engine at peak torque at WOT for five minutes (just add throttle and load till you run out...) the note temperatures on the engine Dyno never exceeded 40C at a 30C Ambient with three small pancake fans sucking air over it. That indicates that for at least that airflow sizing was fine. We noticed the same thing making passes at over 650hp on the chassis Dyno. The "heat soak" most seem to experience baffles us. Look at what air cooled compressors get by with and you realize most of this stuff is either grossly inefficient or blown up to make a statement of some sort. You really need to work backwards from you power goals. Jeff originally sized his for 500 hp, and it's working fine at 650+. Same with his exhaust,, he expected he would see problems over 500, but none yet... He thinks it may be diminishing returns over 700hp, we haven't checked exhaust abc pressure while dynoing so we don't know what part restriction plays in the hp bumpers flattening...but suspect more the turbo is in stonewall than exhaust restriction since the turbo graph seemed to point in that direction as well. You need hp. Hp tells you fuel and air. Air in pounds per hour, combined with turbo compressor map and efficiency will calculate discharge temperature at pressure used... From that you can calculate the required sizing of the core to reject that heat to whatever rise over ambient plus reserve capacity you so desire. It's just math. Math is your friend. Think of it as a "story problem"--except this one is in REAL LIFE like your teacher warned you would happen! Quote Link to comment Share on other sites More sharing options...
bornagain280 Posted January 4, 2015 Author Share Posted January 4, 2015 Okay, I guess its time to do a little reading, research, and math with this equation. I'm going to look around some more on Jeff p and his s130 too, maybe I'm searching the wrong keywords or member searches ? Don't worry, I'm going to do the math work and figure what will work best with my variables, then I'll know what it takes. Not just copying someone else. Thanks for all the information and knowledge from everyone and you tony d. I'm sure to need it again, and corky bells book too. Chase. Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 5, 2015 Share Posted January 5, 2015 (edited) Extreme280ZXT. That should find his Angelfire page I might suggest Bob Tomlinson't book "Turbomania" though it's dated. Corky's method of just throwing boost at an engine makes life complex. Regardless of what he says. Did he mention he has things to sell you? Edited January 5, 2015 by Tony D Quote Link to comment Share on other sites More sharing options...
mildsquare Posted January 12, 2015 Share Posted January 12, 2015 Extreme280ZXT. That should find his Angelfire page I might suggest Bob Tomlinson't book "Turbomania" though it's dated. Corky's method of just throwing boost at an engine makes life complex. Regardless of what he says. Did he mention he has things to sell you? x2 TurboMania is awesome! It Gives you real world results for whats going on and not a bunch of fluff. just Be Careful,it may make you want to buy a set of Dellorto Carbs. Even if you have no use for them. LoL. If it wasn't for my Sk's I think i may have. Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 15, 2015 Share Posted January 15, 2015 It's worse when you find ads for Maserati BiTurbo Carbs on the net and go "well, maybe it would work better with those than with the Mikunis" but then I think "Shift, Ctrl, Arrow Up Up Up..." and go 'NAAAAAAAAW!' Quote Link to comment Share on other sites More sharing options...
mildsquare Posted January 17, 2015 Share Posted January 17, 2015 ^^ I"m gonna make a shirt to explain to my gf that will say "Tony D made me do it!" so I can't get yelled at when I spend money lol. Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 17, 2015 Share Posted January 17, 2015 Yeah, and then I innocently walk through a chance encounter and its "Tony? As in 'Tony D'? THAT WAS MY DIAMOND ENGAGEMENT RING YOU SONOFABITCH!" I shoulda taken Malcolm's advice and been "Tony X" instead... Quote Link to comment Share on other sites More sharing options...
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