OlderThanMe

Wow! I've been following your progress from the beginning and this is really cool! Hope you can finish the other half soon! OTM

I have been reading for quite a while about L6 heads and then about how more modern engines fight detonation. I believe that with slight work to L6 heads (other than opening and closing the chambers to the desired CC's), that detonation can be quite subdued. So many engines that I have seen in life and on the web just use a flat-top piston and create the entre combustion chamber inside the cylinder head. I believe that the ideal chamber would be MUCH different by far from what is currently being used and would be asking much more in the shape of a piston crown than a flat-top that is just asking for trouble. From my readings: Theoretically the ideal chamber shape would be spherereical, with purely mixed air and fuel mixture that would be swiriling and evenly spread, and ignition could come from the center of the sphere. This post/discussion is mainly for combustion chamber events and not for anything in the runners as of yet. It is partially a learning expericnce that I have setup for myself as I am going for a ME degree... So for this imaginary engine build let's just build a maximum effort 3.0 liter turbo L6 with an L28 crank and linered bores at 90mm. It's be nice if some of the L6 builders out there that know a lot more than me about the L series motors would put in some input into my thoughts. Block: L28 crankshaft L24 rods pistons:90mm bore, 35.4mm pin height, 24cc dish Head: MN47 (or whatever head that floats your boat if you like to weld) head closed down to 35CC's but with lots of modifications/opening up of the chamber. 1.25mm head gasket Pics(they are mine and are free to be modified/photoshopped over by others for ideas on chamber design) Here are my thoughts (I'm throwing out "the book" on detonation somewhat): If the combustion chamber(consisting of cylinder head, head gasket, and piston shape) is as closely mirrored from the head onto the piston as possible, then there should be detonation in less places than on a flat piston to closed chamber head scenario. If a high compression engine was built with the afore mentioned and pictured MN-47, I would fully believe that detonation would occur on the opposite side of the cylinder head from the spark plug, where there is a gentle slope up from the squish pad to the valve seats. If you have very close piston to head clearance for good squish, then there will be a "ring" around the squish pad that will be a "detonation prone area". This is my belief of why an all-or-none squish area should be used. If the squish area has a very sharp 1.5mm+ "shelf" by the squish area and moving toward the top of the cylinder head then the "low squish" area would be less fertile for creating detonation. After looking at manufacturer's own high compression racing cylinder head pictures for their cars (mainly drwings of the VRH35Z in the R90CP) and actual OEM cylinder heads that were at a quite high SCR that utilize this "shelf" as what seems to be an anti-detonation implementation. I was highly influenced that the "archaic" L-gata cylinder heads could be revolutionized with modern prevailing combustion chamber designs that take cues from these high end engines. If you look at an L28ET engine, the P90 cylinder head combustion chamber shape is quite a beautiful design. Then when you take a look at the piston crown, the realization is made that much of the squish(or quench) area on the cylinder head is just wasted and is "hanging in the breeze" not producing any(or very little) squish at all. . I have seen MANY posts of people with low CR L28ET engines running moderate boost experiencing detonation and melting all the pistons at once. Why is it doing this if compression ratio is the major factor in creating detonation? I don't believe that a compression ratio all on it's own is what dictates when an engine experiences detonation. It is poor squish that creates detonation. I believe that higher compression ratios could be employed to make better use of boost if more anti-detonation implementations could be used. I found this document put out by NASA which is a great read. These guys know their junk...and funded quite well by the war department in 1947. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930091978_1993091978.pdf The conclusions at the bottom of the above document: CONCLUSIONS The following conclusions appear justified by the data presented: 1. The knocking reaction has been obtained indeprndcudy of either observed pin-point autoignition or homogenous autoignition. 2. Pin-point autoignition may occur independently of the knocking reaction. 3. The knocking reaction may occur at various stages in the development of homogeneous autoignition, 4. High inlet-air temperature and preasurc are conducive to the occurrence of both pin-point autoignition and homogeneous autoignition. 5. The occurrence of knock, pin-point autoignition, or homogeneous autoignition under given engine conditions varies greatly with fuel type. Since our beloved L6 engines aren't producing very high static compression ratios and are run with quite thick air, detonation should be less prevalent than it is. So in order these thigs are most important for building serious power in an turbo L-series engine 1: Airflow. The ports pretty much stink when compared to modern engines. Even when ported they take sharp bends. There are some things I have heard of things done to L6 heads that would be almost considered disturbing but were quite helpful but haven't seen done recently. 2: Detonation. This is the real killer. Turns a grand of pistons into scrap. 3: Lack of displacement. Plenty of things can be done here to "up the ante". L6 displacements range from 2 liters all the way up to 3.4 liters but some displacements depend on your pocket book a little more than others. 3.1-3.2 liters is the "reasonable" limit for most of us. That extra .3 liters to 3.4 will probably cost 4 grand or more over a 3.1 liter. Any way I've been typing and deleting for a long time now. I'd like to hear the input of people more knowledgable than me of the L series engines. (I'm a sophomore in the school of the L6... there are many PhD's out there...)

After hanging out at www.theturboforums.com 900hp seems fairly mild...LOL That is based on a 302 Ford right? I almost went the turbo Ford V8 route.

I'm trying to buy a welder...and buy some other fabrication stuff. That means money for more engines is bad. Plus I have 2 extra L6 blocks and then the L26 that is still in the z which will be coming out soon. Parents are about to take my head off if I bring anything else into our 2 car garage that still holds two cars! (with 3 inches of clearance inbetween the Z and the 944t) LOL Driving the frontier can be frightening... shifted into 5th and smashed my middle broken finger into the dash... ouchie

Dang! That looks like the place to live and drive! Washington? Haven't seen any scenery like that since going to Lake Tahoe!

Turbo headers: Made from 304 stainless tubing .10" thick for durability. Flanges from 1/2" or 3/8" thick 304 stainless. JGS 50mm wastegates I'm going to bottom/side mount the turbos so that they will clear the stock VH starter on the passenger side and the Z steering shaft on the driver's side. That means the passenger side turbo will be shifted forward and the driver's side turbo will be shifted rearward. These pics are taken with a junk Holset H1E for reference Passenger side turbo that will clear the starter: Front shot: Rear shot: Now thankfully the Holset is a little larger than the Mitsubshi turbos that I'm thinking of using so they would have a little more space. I'd engineer the intake tube for the turbo to pass through the engine mounts so that I can use an air cleaner.

Boosted VH45DE(TT) in progress. I wanted to do a maximum effort L30ET but the "could have had a V8" bug was going to bite bad. I figured I'd get a "less-archaic" version of a V8 while I was at it. Why I chose the VH45: 6 bolt mains, forged crank and rods, main cap girdle, hyperetutic alloy block, DOHC, Variable intake cam timing, 32 valves, 6900RPM OE rev limiter but able to go to 7500+ with extra balancing/head work, the sound of a deadly efficient V8, same weight as the stock L6, can be adapted to a Z32 trans, etc... Downsides: Came with auto 4 speed only. bulky small aftermarket (but growing quickly) 1996 model deleted variable cam timing and thus the dual torque peaks which became one peak at ~4000RPMs.

Somebody put that steering wheel in my Z way back when. I have no clue why... its really ugly. Why can't deals like that happen around me? LOL

I have driven my Z in the rain a bit...actually a lot. 225/60R15 cheapo tires on 15X8 rims, 10" 225f/250r coilovers, illuminas 2f/3r, no rear sway bar but stock front one, poly bushings on rear end and steering rack. It was definitely controlable...Go through the corners nice and even and then throttle down and it was a crisp feeling right before started to slide. Better tires would have been nice. Sliding in the rain is too much fun with the nice wide flat torque band of the L6. No swaybar in the back helped when I had the suspension more softly setup in the rear for daily driving. It did roll a little bit though as you can see(all illuminas set to 3 here):

Mario, Well it's slow... Took me 2 days to go from longblock to one head off... LOL. On my own too. I ran 3.2 very hilly miles yesterday and my finger was throbbing by the end pretty bad... I'll probably end up re-surfacing the VH heads and doing some unshrouding of the valves and maybe even some singh grooves. I'll probably get another set of heads ($80 for two heads or $140 for the whole motor...lots of sense there) at the JY and use these ones for my crazy rebuilding work. The car that this motor was from was sort-of maintained. The top end had been pulled apart down to the longblock with the valve covers off. Makes me think the longblock was a replacement one from Nissan or bought as a rebuilt motor. The odometer said 120k miles... Most of these VH45 motors in the yards have 250,000-325,000 miles on them... That is pretty good IMO.

Started cleaning the passenger side head on the chamber side today. Looks like there is some fine FOD on the passenger side cylinder head. Hmm. It's not THAT bad ... Just little pits. It looks as if the pieces of material that caused the FOD may have caused the very slight scarring in the bores as well. I think that I'm just going to wait and buy forged pistons rather than put the $$$ into rebuilding it and just have it blow up from too high of a CR(10.2:1) or some other problem. There may be other problems with the internals but I'm crossing my fingers as it all looks OK. Thankfully I have a work bench now to work on the heads on now. It is made from two pairs of tires stacked 2 high, one bare L6 block on top of each stack of wheels/tires, and a pair of 6x6 logs across the tops of the blocks. In-between the logs I have some fiber-board stuff that was laying around. It's a sight to be seen but it works!

Probably going to do a R200 clsd if I can find one for a decent price. If my local JY gets one I'll jump on it like a kid trying to kill a roach.

It might... but an oven isn't a big deal. Carbon fiber musical instruments have always intrigued me. Light weight, very high rigidity for best sound, and very close similarity for production. Just expensive!

Yeah... I'll create a plug of what I want the INSIDE of the manifold to look like. Then spray the first coat and then add layers of fiber. Then I'd either melt out the wax plug or use some chemical to melt the foam out, depending on what I use.

THIS linked photo doesn't pass HBZ rules soo... It's just linked. LOOK in your own danger... LOL (SFW)

24psi on stock~ish pistons?!?!?! Stock pistons are usually known to be good only to 18-19 PSI for any decent duration of time. Good forged pistons usually go from $550 to $1000+ with fancy coatings etc... They might help in not breaking off the skirts. Also how long do you warm the engine up before hitting any boost? Cold pistons are smaller and have more clearance in the bore than hot pistons. That means that they can "jam" and break off the skirt more easily than if warmed up. Just some of my thoughts...

Haha! I might!! IF this one works with the V8... I'm thinking of using two seperate plenums because of heat expansion across the engine may be enough to crack the manifold in half...which would be bad. Nissan routed things across the engine with some stress relief so I am guessing with the hyperetutic aluminum block there are some expansion things to deal with.

Ron, Thanks for that! Since the price for some decent carbon fiber is about $55 a yard and I may be able to get by with two yards for my motor. Then just put fiberglass over the carbon. I'd need to find a gel coat or at least something to spray down before laying the carbon that is very heat resistant. For some reason I'm thinking of some form of ceramic coating. That sounds brittle though. Maybe if it was suspended in the first layer of gel coat it wouldn't be brittle. TR, You going to help with R&D funding? hehe. J/K!

TurboBricks thread on composite manifolds "Advanced Iduction Research" Honda manifold The Endyn website that sells that manifold also has some great reads about working with engines that have 4 valves per cylinder. They really make power with what they have as a Honda motor...

Geo Metro... 60+MPG. It will take WAYYYYY too much effort to make it fast with the 1.3L 3 cylinder. That way you save your gas money AND insurance money for your Z. Pick one up for $750 and drive it. I'm tempted to do it to save my Frontier from commuting to college 60 miles every day(and spend 1/4 the gas!!!). When your done with it, sell it to the scrap yard for $100. That leaves like 5 grand for your Z car!

So I was thinking... For my VH45DE I could go into Solidworks and design what I'd want the ideal intake tract to look like, then make a mold from wax (or floral foam etc...), spray gel coat, lay a layer or two of fiberglass, then some high tensile strength stainless steel mesh inside the fiberglass and lay more fiber over the mesh. I then have a fiberglass manifold that will most likely be ugly but flow like nothing else. What I'm trying to do is create the ideal shape for the intake runners but not be up to my neck in machining and cost. Obviously an aluminum manifold would be ideal since it is quite strong and light weight... but it can't be molded. I'm also a little on teh poor side to have all of teh equipment to cast such a complex manifold. I've also considered Carbon Fiber for a first layer but it is a bit brittle for the strength. I'd like to hear some discussion on the idea. Thanks guys! OTM

Has anyone thought of using vortex generators in the intake manifold? Since it "works" improving the aero of the Z body shouldn't it work in the intake tract? With the VERY high velocity they may be able to be used to create a counter-rotation that could cancel out the vortecies all-together. Have I injested too much bad cheese or does it make sense? I think the idea of a intake-tract set of vortex generators could create a counter-tornado that could work.

Pulled the passenger side head tonight. I'm going to try to get to the driver's side head as well. For 120k miles I'm impressed. I can see some slight scoring but can't feel it with a fingernail. I'll keep my thoughts on the shortblock to myself until it gets pulled apart because the bearings could possibly be toasted. The head gasket is a Nissan part so that is good. Probably the orginal ones. The top end above the heads had been re-done with that nasty orange goo. I think I'll put the $$$ into a nice Nissan gasket set for the rebuild. I'm considering either getting new sleeves with an overbore to allow for about 5 liters and forged pistons or just leaving it until it blows up. Oh yeah... The timing chain guide on the driver's side of the passenger side was just gone... They were made of plastic until 93... Mine just happens to be a 93 model. I'll get metal guides for a 94-95 model before it goes back together.

Well I would think that doing headers for a VH would be just as hard for a VG series motor... There is a LOT of space under the cylinder banks to route tubes. The valve covers will overhang the framerails but there is some good space at the bottom of the block where it is a little thicker than an L6. One dilemma that I have is that the tranny-engine block bolts are so big that they won't fin in my engine stand! I'll need to drill part of the stand out about 1/8" for the bolts to work. I'll need longer bolts too...