JMortensen

You don't need forged pistons for the kind of rpms you're planning on. If they aren't damaged, I'd reuse the stock pistons. Spend the money on a valve job. Loose bottom end + tight top end = hp. You might want to do a reground cam vs Schneider. I really like their springs, but their cams seem to have a habit of losing a lobe. Might be due to new oil formulations, but the other possibility is the cams are too soft, in which case a reground stock cam is a good option.

I meant to say "check to see if there is a 4th edition" not that there was one. He keeps updating and it's worth it to get the new info.

I think stiffer springs are going to be the ticket.

Evlevo and I have this right. You want the stiffer bushing on the side that takes the braking forces. On a Z or a 280ZX, that's the front bushing. On the Z, the control arm tries to move back under braking, pushing directly on the front bushing. The rear bushing is basically along for the ride. On a ZX the control arm also tries to move back, and the bushing that resists this movement is the front one again. The rear one is still along for the ride.

As Brad says, the limiting factor with the S30 EFI is the analog nature of the FI system. It's set up for stock stuff, so if you put in a cam, it can't adjust. Original S30 FI systems are 40 years old and have issues with bad connectors, etc, that a switch to carbs negates. A perfect running factory EFI unit should compete well with stock 240 SUs on a stock L28 engine. The other issue might be restrictions in the factory intake manifold, but if you compare hopped up engines with cams and headwork, etc and then ran the same intake manifold, say ITB EFI vs Mikunis or something like that where everything else is relatively equalized, you should do better with EFI than with carbs. When you start looking at those options, a motor swap becomes more and more cost effective.

ZX has the same issues as the Z, despite the rods being reversed. If you run poly in front and rubber in back, should be OK, or TTT or any other TC rod with an easy moving pivot will work as well.

There is a little bit on SAE cars, and he mentions the venetian blind rear wing he built for an AP car, but I think that's about it. It has A LOT more info than downforce though. You'll love it.

What is that gauge going to show you? I think it's pretty unlikely that you would have a pressure differential from one side of the caliper to the other. If you had one on the left and the right wheel, or front and back, then you could look for some obstruction in the hard lines. Outside of that I think the pressure to the pistons is going to be the same even if the pistons themselves are frozen.

For anyone interested in the book, Comp Car Downforce morphed into Competition Car Aerodynamics. It's had 3 updates and is quite a bit longer and has more tech info than Downforce did. Here's the latest ISBN, check for a 4th edition if you're ordering, the 3rd has been out for a year or two at this point: ISBN-13: 978-1845847760

Totally agree on all points. MM rear arms had no triangulation and big squishy rubber bushings on the outers IIRC. Bad calibration on that Hunter machine was what led me to run 1/2" toe in and wear out a brand new set of tires in a week. Same thing happened on a customer's car and burned up her rear tires in short order. As to the measuring at home vs laser, I tried to do a string alignment with limited success as well. I think slip plates would really help, particularly with measuring caster. I tried drawing the angle on my shop floor and then measuring camber and it was not repeatable and the car pulled hard left. Can't really do string alignments with the car sliding left to right though. I suppose could set camber and rear toe, then measure caster and set front toe on the slip plates.

You didn't say which bump stops you're running, but if you intend to run really low without sectioning the struts, then a good bump stop will make a big difference. You can get one that engages almost immediately and has a decent spring rate. The ones that Energy Suspension sells are what you typically see on Z cars. They're polyurethane and VERY stiff; they're junk. Many newer cars are on the bumpstops about 1/2 the time you're driving, and essentially any time you turn. You need one that works with a reasonable spring rate if you're going to do the same thing. Here's a great video on bump stops:

Sorry to say, but you have convinced me that your measurements are wrong with this rear toe thing. If they're that far off in the back, I'm guessing that they're similarly erroneous in the front as well. Just take a step back and think geometrically about the rear bumpsteer: the inner pivots are parallel to the chassis centerline. You measured 1/2" toe in (that will wear out a new set of street tires in about a week's driving, I can say from personal experience). Let's assume you had 1/4" toe on each side. Since the inner control arm bushings are parallel and level with the chassis, the difference in length at the spindle would be the difference from taking the length of the control arm inner pivot to the front of the spindle at one angle, and the difference in length at the rear and subtracting. Then do the same at the second angle. You're saying 1" of chassis movement gave you 3/8" toe change. I don't believe this is possible. You have some rake in your car, so it wouldn't be exactly the same amount of change it would be VERY slightly different front to back, but there is no way that you're getting that much change out of 1" of change on the ride height. 20 something years ago I had access to a Hunter alignment rack and I tried my alignment settings at street height and race height--I used to adjust the coilovers to lower the car about 3" when I got to the track--and the rear toe change was negligible.

I can't imagine why this would be the case. When I did mine with stockish stuff I was using a 3/4" spacer and raised the inner pivot 7/16 and that was enough to make my car stop doing a crazy emergency lane change type of maneuver over one particular bump at one track. These cars are old and modified and there will be variations from chassis to chassis, but they should be basically the same if the chassis isn't bent up. This is how Design Products is able to sell a "bumpsteered" steer knuckle for 510s, as an example. The bumpsteer spacer really doesn't affect the bumpsteer, just the part of the curve you're driving in, it's going to be the angle of the LCA relative to the tie rod that will be important, and that should be fairly similar from S30 to S30, barring any front end collisions or mods.

With the compression that high I'm guessing he's using the Maxima N47. Good combustion chamber shape, but smaller valves and I think the ports are smaller too, can't remember for sure. I think this engine would benefit from a whole lot of porting and polishing and some bigger valves. Re: carb size, zredbaron made 270ish whp with his stroker on 40s if I recall. I would go 44s or 45s too, but you can't argue with results. It is at least possible to do a lot better than you're doing with the smaller carbs.

Not sure what to make of Dan's earlier comment that all you can do is change the part of the curve you're in. I've adjusted on my car twice. Once with mostly stock suspension by raising the LCA pivot and using a bumpsteer spacer, and once with custom (slightly narrower than stock) power steering by raising the rack and LCA pivot and lowering the tie rod and using a bump steer spacer. In my case I saw a much diminished amount of bumpsteer in a fairly wide range of motion. I hesitate when I think that Dan is wrong and I am right, but you're indirectly backing me up here, so... ???

A few observations: 1. That splitter should generate some pretty good downforce. Your front springs are very soft in terms of controlling any significant amount of downforce. 2. Downforce increases exponentially with speed; the faster you go, the more you need to control that front end so that its attitude with the ground doesn't deviate and change the amount of force you get, literally from second to second. Flat splitters are pitch sensitive. 3. Lack of rear aero. I would think that the last thing you want is hundreds of lbs of downforce in the front and hundreds of lbs of lift in the rear, but I expect that might be what you have. Looking at the wind tunnel results, they had 77 lbs lift with BRE spoiler in back, and 22 lbs downforce with "MSA short spoiler" installed, although the rest of the car wasn't set up like yours, so we're really guessing at what you would have. Regardless, it doesn't look like a whole lot to me. 4. The more suspension movement you have, the more bumpsteer you will experience. You can't get rid of it altogether, but since it the amount of even minimized bumpsteer will depend on the amount of suspension movement, seems like for that particular issue you want to minimize suspension movement. I like your suggested changes, minimizing camber will minimize camber thrust, and maximizing caster will tend to make it want to go straight. Minimizing bumpsteer is a no brainer. I also like Cameron's suggestion of a bit of toe in out back. What I think you're missing, just by looking at it, so more of a WAG on my part, is both rear downforce and the spring rate to handle downforce. I expect your front end makes more downforce than anything tested in the windtunnel, by a long shot. If you want aero balance without a bunch of drag, you might cut the splitter off the front to reduce front downforce. If you want it to be less pitch sensitive, you could raise the center section of the front of the splitter. In the tunnel they generated 110lbs downforce at 100 mph with what I think is a poorly designed front end on the wind tunnel testing (sorry Roddy). Since the course is likely pretty damn flat, unless you have way too much rebound damping and you're packing down along the length of the course, you can assume that you're generating in the neighborhood of 900 lbs of downforce (225 x 2 springs x 2"). Last time you went I was genuinely concerned for your safety. Anyway best of luck and I hope whatever you do it works better than last year.

If you need it again, the way back machine works... https://archive.org/web/

There is no simple answer to your question. The first thing you'll find is that the valve hits the stem seal after about .470 lift. If you use shorter seals you can go higher, but then the duration of the cam will need to be such that it doesn't put piston and valve in the same place at the same time. If that happens, you can flycut the pistons for clearance. There are L engines running .610 lift cams. I think that's the highest I've seen, but you need quite a bit of modification to do it, and the valvetrain won't last very long with those kinds of specs because you need strong valve springs to close the valves and they wear everything faster. I would ***GUESS*** that most .500ish lift cams won't hit on a stock head with stock pistons, but the right way to check is to put clay on the pistons and rotate it around and see how much clearance is there.

Definitely use modifier. I like SWEPCO 201. Any good quality gear oil will work. Even if they say "for limited slip" you still need the modifier. Some of them are labeled Ford, Chevy, Chrysler. Doesn't matter which one you get.

Might want to read this before you go too far down the BMW route: http://thegarage.jalopnik.com/bmw-engines-are-gigantic-pieces-of-shit-1784684330

If it's half assed, probably doesn't have a thermostat either. A thermostat will at least allow the oil to get to operating temps. WIthout one, the oil won't lubricate as well. That stupid JDM trend of the big oil cooler with the too long braided lines hanging out the front is really a problem for me too. The slightest collision is risking an oil fire.

Z's need a cam to make any power, and the stock FI can't deal with a cam. The MN has tiny valves, and the compression with that head is very high. I would suggest an aftermarket FI system or a switch to carbs and a healthy cam in there with some headwork. Do all of that right and you should make mid 200s hp. A 280ZX NA trans from a 80-83 will have better ratios for use with your 3.70 gears. The 280Z 5 speed has wide ratios and a big gap between 2nd and 3rd gear.

I like BluDestiny's suggestion of a regrind. I don't think anyone has really proven it beyond a doubt, but those Schneiders seem to lose lobes more often than regrinds. Their valve springs and retainers are nice though, not too much seat pressure, etc. Need shorter valve stem seals.

It was my Nissan Master Tech former roommate who helped me build my car back in the 90s who sold me the cam, and his warning was: "It's too big, won't have any bottom end" etc. He had been running a high lift low duration cam in his 510 with Mikunis and I had one in my Z too. That thing was a waste of time. Might have given me 5 whp. Maybe. I put the bigger cam in and was really impressed. I would guess I gained 40 hp. No detectable loss on the bottom end, ran out of steam around 6000, but that was the carbs. Later put Mikunis on it and it would slam the rev limiter hard. Then I had the front crank bolt back out and the pulley wobbled and ruined the end of the crank. After that I built a flat top bottom end which was closer to 11:1 and then I thought I needed more cam but it pulled hard. Anyway after I initially installed the cam I took it over to his shop and let him drive it and the next day he ordered a .610" lift cam for his car... LOL. People follow 50 yo SBC cam recommendations for the most part and a whole lot of people go too small on the L cams IMO. I can't stand seeing Schneider .460 lift cam in a build list.

It will be fine. I had a similar motor with a .490/280 cam and was told how terrible it would be. Was a pretty huge improvement over stock with SUs.