JMortensen

I would expect an L28 at 9:1 to make more power than an L24 at 10.5:1, especially on pump gas. If you have to pull back the timing to get it to stop pinging, you're fighting a losing battle. There is some hp in those last few degrees of advance. EDIT- My L28/E31 had about 11:1 compression and needed 95 octane to not ping with mid 30s advance. That was with a bunch of headwork done including grinding off the spark plug threads that stuck out past the plug in the chamber and smoothing out every other sharp edge that might lead to detonation.

Type this into google: "destroker site:forums.hybridz.org" Lots of threads on it. Simple answer is that the stroke of the L28 is not the limiting factor. You can build it to rev as high as you can your destroked motor, but with the destroker you're losing displacement.

Bad idea IMO. As you adjusted caster you'd put major stress on the threads. If you made them to the length where they fit into the TC buckets without loading the threads, maybe that's OK, but the idea looks to be to make everything adjustable. Another possibility would be to get a male clevis that screws into that existing threaded hole, but if there's not a whole bunch of money tied up in it I'd rather have a clevis welded to the arm and a solid heims joint or "rod end eye" as it's sometimes called on the TC rod.

I wonder if you couldn't just put a really big fuel filter on it and use it like a surge tank. Or an actual surge tank would probably cure the symptom if you don't want to dissect the tank.

Don't want pivots at both ends of the TC rod. Rear pivot only. Front attach point needs to be strong, and ideally the TC rod itself would point as closely as possible towards the ball joint pivot. That loads the TC rod straight on. If the rod is offset inwards (like drifters tend to want so they can get more steer angle) then the rod itself and the attach points need to be strong enough to take the side loading involved.

Did corner weights over the weekend. Drivetrain offset 1.5" right. Fuel cell is offset right as far as possible. Rad slightly off to right. Driver's seat 1" right. This is with me in the car and the hood on.

Look at zredbaron's "no shortcuts" thread. I went with him to dyno the motor. The 45s made another 27 hp if I remember correctly, with very little lost on the bottom end.

'70 240, L33 5.3L AL block, carb with (heavy) aluminum intake manifold, flexplate and button clutch, T56, R200, probably too much cage, plywood splitter, super wide body, 15x14 wheels, stripped interior, no pass seat, 2370 lbs.

First, a rear steer device. If you go look, you'll find that Super HICAS delete kits are pretty popular in the racing scene. So yes, they may be there as either a techno sales gimmick or as a way to reduce the turning circle, etc, but they aren't very popular among racers. Even if you subscribe to the idea that they get deleted because of weight, that still means that the weight associated with it, which is maybe 30 lbs isn't worth it, in a race car that might get down to 2500 or so. Secondly, I agree completely that the amount of toe change is the key here. If an out of the box 280ZX had a mm or two toe change over its full range, I certainly wouldn't be complaining about it. But I think it's quite a bit more than that. FWIW, lots of people here, including me, have suggested pretty heavy toe in on the rear of the S30. I think if you look you'll see that I always recommended about 5mm (3/16") total toe in, which isn't a small amount. For what it's worth, I once got a "bad zero" on the alignment rack at the shop I worked at 20 years ago and set the toe at something more than 1/2" total toe in, and I wore the brand new rear tires on my car out in about a week. I did do really well at an autox at that time though... As a static setting, toe in provides the stabilizing effect of the outside tire driving inwards, but the toe angle doesn't change mid-corner with bumps on the track. If you could get a mm or two of toe through the whole range, the effect would be very muted and my complaints about STA rear suspension evaporate, but STA suspension isn't normally anywhere near that good out of the box, and the big squishy bushings aren't helping anything either.

I'm not a suspension guru either, but I think I have a pretty decent handle on this subject: dynamic toe change is bumpsteer. Do you prefer bump steer in the front? I know John Coffey talked about running different spacers left and right on some tracks to get better dynamic toe out of one side for tracks that had a lot more right turns than lefts, etc, but for the most part the consensus amongst racers is that less bumpsteer is better, and if you want to change direction of the wheels, you do that by inputs on the steering wheel. There are some pretty sophisticated link setups out there that feature dynamic toe changes, but the idea for me is that I don't want the toe changing without any input from the driver. What's a bigger sin IMO is using huge squishy bushings that allow toe change. Either way, bumpsteer on either end essentially causes hysteresis: the toe changes due to compression or droop of the suspension, which forces a change in the traction at the contact patch (can't steer the tire around without changing its available traction), the changing toe has an effect on g forces which causes the body to bob back and forth, which changes the compression of the shock, which adds more toe change, wash, rinse, repeat. I had my Z in a pretty bad part of the bumpsteer curve in the front end for a while and I would go through a sweeper and experience this firsthand. The car would roll, steering angle would change to keep the car pointed in a straight line, then it would come back, steering changed again, then it would roll more, etc. One of the most noticeable improvements I found after minimizing bumpsteer in the front was that I wasn't constanty sawing at the wheel on sweepers to keep the car moving in a consistent arc. The more bumpy the turn, the worse the effect. A car with less bumpsteer on either end of the car should tend to be more stable, and I think you can show this tendency in semi-trailing arm setups by watching older 911s spin at track days. I used to go to Porsche HPDEs when I was working for a Porsche shop 20 years ago, and I saw that phenomenon in person more than a few times, exacerbated by the rear weight bias no doubt. Don't get me wrong, as you've said so many times, there are plenty of fast race cars with semi-trailing suspensions, and having dynamic toe change doesn't mean a car can't be fast, but reversing the logic that dynamic toe on a fast car proves that dynamic toe is good or desirable doesn't work IMO.

420 with what bottom end? I want a straight up comparison to that diesel block 3.35L build. I'm betting yours would be right in the same ballpark. Honda knows a thing or two about valvetrains...

Found it on another forum where they were looking at different suspension setups for an AWD V8 swapped XR4Ti. http://www.corner-carvers.com/forums/showthread.php?t=49547 Definitely a DIY thing, and also won't eliminate the toe change, although there was some back and forth as to exactly what the difference would be.

I had one of the old Mulholland bars at one point. Can't even remember why I had it, was a long time ago, but IIRC it was really very similar to the rear mounted ST bar. One thing not mentioned previously in this thread is rebending the bar. I found that my ST bars bent very easily with my HF press (12 ton I think). You might be able to modify the angle in the arms to get clearance and make it work. Literally just took the bar, laid it across the table part of the press, then jacked the jack into it and bent it that way while holding onto the bar. Surprisingly easy.

Having had a garage ported E31 and .490/280 cam I wouldn't hesitate to run a .500/300 on a similar build. An overcammed engine might be a problem, but so is having an undercammed engine. My friend who built the first engine for my Z was super conservative with his cam picks. He had this grinder who made a very high lift very low duration cam. It might have made 5 or 10 hp over stock, maybe. It was so minimal you could barely tell the difference. He had that .490/280 cam sitting around, had actually gotten it by accident instead of his usual short duration cam. I bought it from him despite his warnings about how much it would suck on the street, and when I put it in I had to have gained 40 hp and the bottom end was as strong as ever. It was a huge increase in power. Brought it back around and let him drive it and he immediately went and ordered a much bigger cam for his L18 race engine. When I later went to triples I felt like I needed more cam again, but instead of putting more work into it I ended up going V8. YMMV, but I managed to get really good results without a flowbench.

Yes. That is absolutely right. But if the frame rails flex towards the firewall more than the rails flex the opposite way... My ***guess*** is that the beam loading of the whole chassis under braking has more effect than the strut towers trying to fold forward under the brake torque.

I don't honestly know. All I can tell you is that if you can watch the frame rails flex, presumably the strut towers are moving too. I guess the question is: what happens when you push really hard on the end of the master? What would be really interesting would be to take some measurements on how far the strut towers move back towards the firewall under heavy braking. I have the feeling that they move quite a bit.

I know more modern cars do this all the time, but the Z chassis is SO flexy that I'm wondering if it's a good idea. When I put jackstands under the TC rod buckets on my Z I could WATCH the front end droop 3/8 or 1/2 inch as I lowered the front end off the jack (jacked up on the xmember). If you don't take care of that weakness first and you just use the strut to the master as a brace, I'm just concerned that the pressure on the master could cause problems. Fabrication looks very nice.

I am running them with a slotted xmember.

John gave specific guidelines for ride heights, etc, that he got from ITS racers and his own experience. I don't really think that's the best idea; I would prefer that the guidelines should be more general. Correct spring rates should be figured out by what is necessary to manage body roll, heat up the tires, prevent the car from bottoming, etc. Stickier tires will necessitate more spring. This fact alone would be an obvious limitation of a specific spring rate suggestion. Even if you don't change the tire size, a Yokohama A008 in 225/50/15 from 1993 will be nowhere near as sticky as an A7 from 2016, but people are running all different sizes these days. Race ride height should be as low as possible before suspension geometry becomes an issue while also being sufficient to prevent the car from bottoming frequently. The more you're willing to modify the car, the more extreme you can go with all of this stuff, eg if you want to run the car really low, you can do that by modifying the suspension pickup points to correct for roll center heights, bumpsteer, etc, and then you can run much stiffer springs to keep off of the bumpstops, etc. If you're just going to bolt parts on, using John's guidelines will get you in the ballpark and you can tune to your preference from there. For my part, there are a lot of guys here who know better than me. I just had a lot of time to post, and when I was building my car I modified just about everything and had long conversations about what should be changed and why. I had some new, original ideas, but a lot was just taken from other people.

I don't have a recommendation for 2+2 rates, but I would think the 250/275 would be fine for a weekend warrior. If you run camber plates, you'll lose about 1.5" on the front height and 2.5" from the rear without doing anything else. Since most people want the car level or raked a bit, you might end up too short in the rear. I've only sectioned 240 struts, so I'm guessing on the 280 stuff, but I've seen numerous threads over the years from people who went too short in the back on the 280 struts. I'd keep searching or find someone who has 280 experience before you cut. I would think you'd want to cut the front and leave the rear. If you didn't have enough height in the rear you might have to add more in to the strut tube instead of removing it. Keep your pieces that you take out of the front struts, maybe you could weld them into the rear if necessary.

Interesting. I was actually considering this and had thought of attaching to the strut. Glad I didn't do it now.

You can use the MR2 shocks, no problem. If you are still using rubber isolators, you can save yourself the hassle of sectioning the rear struts by grabbing some 240 isolators and running them in the rear. That will drop the car 1" without doing anything else, then you just make the spacer to fit the strut insert. When I did this about a decade ago, I found that a 1.5" x .095 tube fits the BZ3099 just right. You can buy that on www.onlinemetals.com by the foot. http://www.onlinemetals.com/merchant.cfm?pid=7562&step=4&showunits=inches&id=283&top_cat=197

VLSDs have 30 spline inners with longer shafts and spline sections. Pic: http://s38.photobucket.com/user/soapsuds43/media/J30VLSD007-1.jpg.html

LSD > welded for autocross, road racing, sporty driving, etc. The tighter you shim an LSD the more push you get, but you can get the traction with a lot less push out of the LSD vs a welded diff.