AydinZ71

If you are going for "easy" vs. "cost-effective", then you could just ask Hussein (Protuners owner) for everything he is willing to supply you. I know he sells injectors, ECU, etc. don't know about the rest. For pistons, you don't have to specifically ask for "recessed rings". That is a specific observation between the OEM L28et pistons vs. the OEM L24/L28 pistons. It is what Nissan did, and it made a difference on ring life. Just make sure they are clear on your displacement vs. power goals and that its a turbo application. They should have the experience to make the right piston for you. Most of the custom design work will be your electronics and fuel system. So, you should should sketch it out on paper until it all makes sense to you first. That way you don't buy parts you don't need and don't have missing parts. Here is an example of a robust fuel system design that will ensure high confidence you will not experience fuel starvation, regardless of HP (as long as the individual components are rated appropriately): Tank (modified for EFI, or brand new fuel cell) -> low pressure fuel pump -> fuel filter -> new 3/8" fuel line (OEM is pretty narrow and no return) to engine bay -> empty into surge tank -> HP fuel pump picks up from bottom of surge tank -> fuel rail/injectors -> FPR with return -> surge tank again -> surge tank overflow into OEM fuel line used as a "return" back to tank. You should confirm ALL of your driveline components will meet the 300ft-lbs flywheel torque. That includes the new CV shafts, driveshaft, trans, etc. Hubs i believe are OK to at least 400 ft-lbs, and Nissan 4/5spd should be OK to 350 ft-lbs as long as you are not "launching" at a drag strip. Do you own research though, plenty of posts and experience on this forum. Just run your CF clutch for now and maybe it will hold up? Not a catastrophic failure point, the clutch will just slip if its too much torque. You will need to convert to a top-mount or solid bottom-mount for your R200. The OEM rubber mount on the nose of the diff "pulls up" violently with lots of torque. Best-case your driveshaft U-joints will wear out pre-maturely. Worst-case, your diff mount will fail and the driveshaft will bind catastrophically, assuming your OEM diff over-strap is worn too (do 260z's have these?). do some research on a quality intercooler. You can piece together your own plumbing with pre-made mandrel bent 2.5" AL tube, straight lengths, and silicone of V-band joints. I prefer silicone of IC plumbing and V-band for exhaust. You need a BOV too, but get a "real" one. One that actually dumps some decent volume, not those little squeaky ricer ones. On turbo sizing, if you are going for garrett than use their online sizing calculator. Its free, and shows you precisely where your airflow demand is relative to the curve. The goal is to stay in the highest efficiency zone for as much of the airflow/RPM curve as possible. I think the best way to go from here is to prepare a complete and comprehensive list of parts, upgrades, tasks etc. We can review and fill-you-in on what we see is missing. Unless you are paying someone bookoo money to build it for you, you will need to understand as much of this as possible. You will have troubleshooting to deal with when its all put together and you will want to solve it yourself, if for nothing more than convenience. I don't have direct experience on a before-after on the cooling system mod, but the idea is to get the coolest water back to the last two cylinders. When done correctly, it can not hurt and will only help. the cooler the water jacket, the cooler the cylinder walls, the longer your rings will last, and the higher your detonation threshold will be.

sorry friend. I don’t know anything about troubleshooting factory EFI electrical/electronics 🤷🏽‍♂️. My experience is with carbs and independent, tunable EFI.

Absolutely agree Isocyanurate is toxic, but it is in almost every 2-component epoxy and urethane I have ever worked with. Spray Max is just 2-component in a can, and a plunger to release the hardener. 3M respirator with the right carbon scrubber canisters should do just fine with these chemicals. These respirators aren’t very expensive. I don’t spray any sort of paint or coating without wearing a respirator though, and I encourage everyone else to do the same. Even spray-on enamel has chemicals that will cause long-term harm if breathed in often. Isocyanurate is also toxic to the skin and eyes, so I only brush it on inside my garage. I do any spraying in my driveway.

@NorthStar IMO, the reason you get a broad spectrum of responses is that they are all partially correct and very few have actually done it themselves to understand or experience the nuance. Then, there is the ego to always need to be “right”. Premature ring wear is a thing, and it gets worse the higher your CR and boost on OEM pistons. Yes, pistons are the weak spot for Modest boost. Forget Robello. That’s for a full engine build or “kit” that is specific to an L-series. You can get the pistons direct from CP carillo, JE, etc. take your pick, but it will most likely be whomever answers your phone call or e-mail. Everyone is busy right now. are you comfortable doing your engine math? You can use an online calculator. I believe your OEM CR is 8.3:1. Personally, I’d dish your piston a bit to get 8:1 or less, or get a P90 head which should drop your CR without changing piston geometry. There are plenty of sites that provide the OEM volume of various L-series heads. n42 is a decent flowing head so you can keep it. One thing you could do is go ahead and run your engine with the OEM 8.3:1 CR long block, do the cooling mod rossman recommended, and do all the other upgrades. Keep your boost modest (8psi) and I’m sure she will be fine. As I said before, if you are not detonating, she will hold together and worst thing you will experience is premature ring wear. Not only will you gain experience on what it’s like to turbo an OEM long block, but it will give you time while your forged pistons are being made. OH, duh… you will need a turbo exhaust manifold and EFI intake manifold. For exhaust, OEM for around 350, or protuners for around a grand. OEM EFI intake manifold is just fine for the power you are looking for.

PS: the one-piece fender nose cones will also be boxed out with AL cladding. So will the headlight orifice. Anything to reduce/eliminate the massive turbulent Eddie currents experienced at speed.

gosh darn… ok that’s two folks now 😂 Greg told me the same thing… he recommended a third, middle pin. I was postponing it, but it clearly seems like an important step. Damn, more tube work LOL. thanks Cary! Il get working on that. You can see from the pic below that the ram air will be forced through my engine intake (right side funnel), the fresh air intakes, most will go through the rad, and the rest will be struggling to go over the rad support or under the lower cross support. I plan to add aluminum cladding on the bottom (restrict airflow from diving under the rad support) and and top (restricting air from going between the upper rad support and hood). as you said, if FG hood bulges in the middle, that aluminum cladding won’t go with it and the air will get by anyways. Once that happens, the hood will bulge even more so no Bueno. One thought would be to pin the cladding to the hood, but I can’t see how that will seal reasonably well, and simultaneously not make removing the hood a PITA.

250 at the wheels, and reliable? Ok, here is what I recommend: 1) Custom forged pistons designed specifically for a turbo application. Rings are typically recessed to reduce overheating and premature wear. I assume you still have the N42 head? Get a piston with a slight dish so you get down to 8:1 or less. The lower the CR on a turbo application, the less off-boost response and power but you will have a wider margin to run higher boost before detonation on pump gas. I have turbo'd an L24 with OEM pistons and ~8.8:1 CR. It worked, but the rings wore-out in about 6-months of daily driving and i started getting considerable blow-by. 2) OEM crank and rods are just fine up to 350 ft-lbs of torque. Some folks have taken it to 400 without breaking them. The rods will give before the crank. 3) Independent EFI and an integrated wideband O2 to help you tune and ward off detonation in real-time. Go ahead and add a knock sensor while your add it, to automatically retard your ignition timing and dump extra fuel in. The forged pistons will give you some piece of mind if you detonate during tuning or a hot day etc. 4) at least 400cc injectors. I still use the old-school Bosch 75' Mercedes 450SL injectors. I believe they are 420cc. 5) convert to EFI fuel system. Consider a high-flow high-pressure fuel pump, quality FPR w/ manifold pressure reference. I have a low pressure pump near my tank, a surge tank in the engine bay, and the high-pressure pump is up-front as well. 6) quality IC and 2.5" plumbing. 7) T3 super 60 trim is plenty big enough to get you the power you want, but consider a modern more efficient small-frame turbo like a G25. 8 ) Weld a turbo oil return nipple onto your oil pan. In addition tot he upgrades you are already considering, you will need a clutch that wont slip at 300ft-lbs of flywheel torque (which is minimum what you need to get your 250 WHP. I am sure I am forgetting some stuff. I can go on, but those are the important items. Just FYI, the ITB's look super cool but they are not enough to give you appreciable power for an NA application. if you want to make over 200hp WHP on an NA L26, you will need a wild cam, up your CR, quality header, so on... The ITB's just "add" to the flow capability of an already heavily modified cylinder head, but they don't do much all by themselves. I assume you mean a weber side-draft type carburetor or EFI ITB's. Either way, they are an upgrade to the SU's and will certainly see more power, but their true potential is when you are flowing a lot more air through that head. ITB's certainly have the "cool" factor, but they are not the "source" for greater engine performance. -Aydin

@mutantZ ah so you have a clutch LSD? My helical unit uses gear-oil. No special clutch LSD oil for me . The high-quality clutch units (like OS Giken) can be tuned but I’m not a good enough driver for that to matter. It may be best to get her on the road and get a feel for when and how aggressive the torque comes on. It would be difficult to take a guess on what the best ratio will be for you without every single variable on the table (torque curve, redline, tire diameter, trans ratios, what RPM you like to shift at during normal driving), and for street cars it often comes down to driver preference. i don’t really want to shift a bunch of times just to get up to 60, so I prefer taller gears and final ratio. If it was a track car, there absolutely is an ideal ratio that would give you the quickest lap time, but for a street car it’s more important to stay “modest” and not go crazy on either extreme. the lower on the rpm band the torque hits (specifically for turbo, since NA has a much flatter torque curve) the less mechanical leverage you will need. What rpm the torque spikes will be dictated largely by the size of your turbo relative to displacement, and more minor considerations like how much intake volume you have in your IC loop (lag).

how much torque are you planning on running, and where in the rpm band is it peaking? Comparing trans and rear ratios with OEM and your own personal experience is a great idea. However, if you are pulling a much higher torque/weight ratio than the car or you may be used to, I would pick a lower number rear ratio. Speaking from personal experience, my 300ft-lb L28et 71’ was almost unusable in first gear. Too much mechanical leverage for the torque. Tires want to break loose, and you don’t stay in gear long enough to make-up for the time lost in shifting to 2nd. I would often short-shift just to get back down into lower rpm’s and run out second gear for longer. This was on a Nissan 5-Spd wide ratio, and a 3.7:1 LN from a Z31. you might want to collect a few rear ratios and dial-it-in to your liking (unless it’s a track car, which would benefit from bench calculation and specific track avg spd..) 3.9:1’s are still floating around out there, but 4.11:1 in an R200 case are hard to find. if you are running less than 250 ft-lbs and are not “launching”, you still want a 4:11, you can find that ratio in an R180. They came in a bunch of Datsun mini trucks. I have one laying around I bought last year for $40. also, you can still find R180 3.9 helical LSD from a subie STI. I believe the yrs are 05-07’

@jhm @clarkspeed thank you both, sincerely. I may be a smidge perfectionist, and I say that equally as a criticism and an asset. I think I have frustrated the heck out of Greg by now LOL. “Dude get that tub on the track” haha I have some serious EP GCR challenges with the tube steel, but if I suck as a driver I doubt the judges/competitors will press the point. I suppose it would be a welcome problem to have. Most of this will be hidden under aluminum cladding. No better feeling than when you take the hood back off, place it back in the car, and hear that sweet “click” noise without the car putting up a fight. you can see what I did with one of pics. Welded the tube into the general “location”, then welded the pin mounting plate directly to the tube with the hood on, all from underneath. That’s how I ensured there was no lateral load on the pin. The hood flexes quite a bit, so I could not rely on dimensions off-car. i plan to put in two rubber bump-stops mid-way back under the hood, as the hood “sits” flatter than the fenders. Need a little encouragement to sit-up.

front hood attachment points for 12lb fiberglass unit. Anyone who has mounted a custom hood with new attachment points for the first time knows how hard this is… like, yell loudly from time-to-time, frustrating. Like… 2hr estimate turning into a week, difficult. Using very thin-wall stainless tube. 4’ of tube is under a pound. Pin is 3/8” quik-latch. Pin mounting surface is 16-gauge CS.

Rear hood latch complete. Sounds rediculous, but this was HARD. Needed to get under the car with the hood on, center the hood and weld it in place from underneath. Of course I could have oversized the latch hole considerably and just adjusted to fit, but I didn’t want to weaken it. Now into the front mounts, which are a heavier gauge quick-latch (3/8”). OH, and I got my adjustable cam gear. IMG_7395.MOV

Ah! This was installed by the previous owner, but I kept it. Picture yourself in the drivers seat. There is a roll bar between your seat and the inner rocker panel (SCCA roll-cage spec). Now picture that roll bar continuing through the drivers toe plate (firewall), then bending towards the tie-rod attachment point. All this to say, it’s a single continuous section of roll bar that was “bent” inward, vs. 2-pieces. the roll bar is MUCH thicker than the tubes I used for chassis reinforcement. Nearly 1/8” thick wall, vs. 18-gauge for the stiffening tubes. there is a ton of force on that tie-rod attachment point on a race car (slicks/grip + hard braking), so that bar helps counter the force and reduce body flex and poor response.

Looking great!! here are some pics of mine to give you some ideas. The idea being, there are means of stiffening the towers that don’t need to introduce more bulk to the engine compartment. Looks like you are on the right track! Good luck! these are old pics so the chassis Has progressed since then, but they capture the individual tube supports.

Ah! Greg’s got similar sliding mount on the latest (Orange) CP tribute he is building. What thickness did you choose for the mounting surface? I totally get trying to save a buck! My GC plates (bolt-in for EP) were close to a grand for all four corners IIRC. I was (and still an) a suspension geometry noob so I wanted something that I knew for sure would keep the spring and strut concentric. I don’t have a lathe so I’m limited on fabricating precision components. how do you confirm tower mount consistency? I’m anxious all my rust repair may have warped the structural alignment a bit.

Wow! That’s a lot of work making individual suspension components! Tell us the angle! Saving weight? Money? Adapting to unique shock dimension? I can already see it is lighter than my Ground Control sectioned OEM struts. Just curious what you are going for. Looks great though! Tons of detail in there.

I’ll take that as a compliment! I probably try 5 things before the 6th one qualifies for a “good idea” 😂 me too! I learned about the megajolt (EDIS) crank-fire ignition on here. Greg hadn’t heard or it, but who would when you can afford electromotive 😂 I find it difficult to separate the “marketing” from truly value-add components. In many cases, something hand-fabricated is the only way to add adjustable and still meet class rules.

@tube80z Very helpful Cary! The sprung splitter was great idea! Il give the 10mm birch plywood a shot. I feel the standard 3/4” cross section (sometimes sold as 4/4) is too thick and heavy. The EP rules are quite restrictive. No new openings between fender and engine bay. No non OEM hood or body vents. Splitter must stop at leading edge of wheel well opening. Explains why Greg uses what I’ll describe as a “skimming” skirt since we can’t blind-off the bottom of the car beyond the front. Still… rules help to keep my budget down 😂. Unless you are a magician with a fuel cell there is a ton of Eddy movement behind the rear skirt. I might attempt to block it off with some 0.032 6061 AL, but my gut tells me the officials will notice it. Heck even my new fancy fender nose cones are illegal 😕. Should have assumed Greg’s EP car didn’t have them for a reason! His CP tribute cars all do though. It was just so tempting to shave all that weight off the leaving edge. The 3.5lb setrab oil cooler was a hit in the wrong direction (but we’ll worth it!). even my fancy engine-to-cowl vent relief is likely illegal. At least on that I can simply blind it off with 20-gauge steel.

Gosh you know, all the L engines are oversquare, so you are right. It’s relative. Even at 86mm stock bore and 83mm V07 crank, I’m sure she revs great. a credible source in the S30 racing scene said he isn’t a fan and feels the longer stroke tended to break things prematurely. Didn’t get into much detail, but he prefers an L24 crank on an L28 block 🤷🏽‍♂️. As always, I’m sure there is some truth, some opinion, and some experience mixed in. I have not had an opportunity to discuss 3.0+L motor longevity in a pure, competitive racing application (many laps at max power band). They are not legal in most classes (except “open” classes), which explains some of it.

Cut off the little unibody appendage forward of the fender. Mocking the “nose cone” mounts, and contemplating the hood mounts. one fender officially fits and gaps look good (so far). going to box the nose cone with AL sheet.

@JMortensen Gosh I have been debating 6061AL sheet or plywood. I’m only allowed from leading edge (air dam) to the front of my wheel well arch’s. Not a whole lot of length, but I’m certain it’s a critical addition. Jon is your plywood a standard 3/4” section? I don’t recall other standard thicknesses, but maybe 3/8” is available? The Russian birch plywood is 10mm and stiff as hell. Was thinking about that… If I do it in AL sheet, it will certainly need some stiffening. I don’t want extra load on the fiberglass dam, so I was thinking of some cantilevered supports (attached to the lower rad mount crossmember) but it will take some thought 🤔 also, do you run a flexible skirt on the leading edge of your dam? Greg uses one (pic attached) but might not be critical for the slower speeds of autoX. This piece is a “consumable”, since it is bound to make contact with the pavement.

gosh, I’d imagine 25 feet would be enough from front-to-back. I bought a 6’ 3/8” galv steel inverted-flare line from auto parts store for fuel. Got me from my pumps to the shifter cut-out. 4’ section got me the rest of the way to my filter/regulator. Mine is mounted on fire wall though, not the wheel-well.

@ozconnection Short-stroke motor’s are great for maximizing HP with limited displacement. I think your limiting component will be the head though 😕 . Custom rods will get you safely past 7500 rpm. I’d pour the rest of my time/money in the head. 2 valves per cylinder and restrictive ports takes a lot of work to maintain torque past 6500rpm. Good luck! PS: Kameari and Tomei still sell parts for the L20A, but they are crazy expensive

At the risk of not reading your thread in detail (thanks ADHD), I do want to suggest chassis stiffening. I have driven a friends race car, and then jumped in my 71’ L28et street car. HUGE difference. You didn’t mention your spring rates, but I will assume they are somewhere between a race car and OEM. High torque and stiff springs is a combination that may put too much stress on the chassis, without stiffening. I see you have a 6-point roll bar. That’s a wonderful launching point to complete the rest of the cars stiffening. If you don’t mind (your chassis is not rare, yet), welding a permanent support between your rear strut towers, with diagonal stiffeners (will look like a “K” turned 90 degrees clockwise. This adds much more rigidity than just a fancy strut bar. Those are design yo keep the top of the towers separated equally, but allows for independent movement up-and-down. I assume your roll bar terminates on your rear towers already. That’s a must. the roll bar does not do much for the front though. Consider adding tube steel from the front strut towers to your firewall at an angle point towards the centerline of the car. Then pick-up from the cab side of the car, and add a tube to your roll cage. Many pictures online of race car S30’s as an example. you can add a vertical stiffener on your strut towers down to your unibody frame rail. Just remember, the high stress applied to your chassis is at all four towers, your engine mounts, and your diff mount. Therefore, no need to stiffen in front of your front towers, or behind your rears. Although stiffening outside of this footprint does still help, you are adding weight that is “cantilevered”. Not supported by 2-sides, but like holding a grocery bag with your arm outstretched. stiffening the chassis will add steering and acceleration response. With engine/turbo/trans/8.8 (unless you have the AL housing from an auto) your car is going to be at least +150lbs heavier than OEM. More weight also contributes to more chassis stress, along with the stiff suspension and extra torque.

Gosh I have one but I’m still months from moving onto the street car (with the L28et). The unit is gorgeous though, and Godzilla’s video instructions were very helpful. Better than a flimsy 8.5X11 sheet of paper if that gorgeous DOHC ever has enough volume to sell for a few grand, I’m all in!