JMortensen

Many newer strut suspensions use dual ball joints. I know BMW uses them on some of their vehicles, new Mustangs, etc. Not sure about Porsche. You still have to take into account that the Z was designed for a 175mm tire and when you put wide enough rubber on it to compete with today's cars they have issues with scrub radius and the more modern cars aren't running the same caster, ackerman, camber gain, etc that you'd find on a 1970 Datsun. Grafting on a SLA setup that has better geometry should actually produce gains in performance. Not sure why you would argue to the contrary.

Agree with Ben. Struts can be fast, but it's harder to get them there. The other issue with struts is the dearth of racing quality struts. Race quality shocks are readily available and much cheaper if you compare like for like to struts. I wouldn't do a Miata front end. The suspension geometry is great, but they have weak bearings and racers have to replace them a lot. Maybe a RX8 or something bigger. Mazda really does build awesome handling and painfully underpowered cars... If you're going to fab it up, I'd suggest looking at circle track parts. They have everything you need from prebuilt control arms, hubs, uprights, all the way down to weld on bosses for shock mounts. The problem is that the angles of the arms and length of the tie rods and all the particulars have an effect, and just because it's SLA suspension doesn't mean it's done right with camber gain and bumpsteer that is better than what you started with. Takes more math and geometry skill than I have to figure all that out, which is why I'm still on struts. I'd avoid the Mustang II prebuilt subframes that you see on drag racer sites. My understanding is that they usually have terrible geometry.

Fair enough, I can see how just a peak flow wouldn't be sufficient. I think something that is fairly instructive though is zredbaron's first stroker build which IIRC has had a small cam and no porting and made something pitiful like 160 whp vs his current one with the ported head and very particular cam profile that puts out 270 whp. He's a details guy, might PM him and see if he still has the rest of the specs you need on those flow numbers.

From: i just got my e31 head from sunbelt, am putting it on tomorrow. the printout i received showed the following data: stock (head before any work) port flow: .......................intake.................exhaust .425" lift...........158.9 cfm...........110.2 cfm .525" lift...........163.5 cfm...........118.4 cfm (.525" lift never reached with the cam i had in it) final port flow: .......................intake.................exhaust .425" lift...........180.6 cfm...........129.3 cfm .525" lift...........201.6 cfm...........145.1 cfm according to sunbelt, 200cfm by their flowbench (flow pro) is 225cfm by anybody else's (super flow). the cam jim set me up with has a lift of .520, and powers from 3500 - 7200. i think the duration is around 280. this is the max lift (valve-piston clearance) you can put in a 3.1 stroker without cutting valve reliefs into the pistons (using a 2mm gasket). the stroker kit produces a positive deck height of .025". hopefully i can dyno the car this week and let you know what this puts to the ground with a 3.1 LD28. i have pics, but won't post until i have guidelines since i remember john coffey saying something about sunbelt not liking that. john coffey, my 3,4 exhaust ports do look "funny" (but why do that only to cyl 3 and 4?)and i have single springs. all in all, i'd say ~225cfm per cyl is pretty damn good for an e31...i cant wait to hear and feel it!

What are these graphs supposed to show? HP and torque with the .480 vs .540 cams on stock and ported heads? If that's what it's supposed to be, I have to say I don't think they're very accurate at all. My takeaway from these graphs would be that porting is a waste of money, but my personal experience and the experience of a lot of the people on this and other forums is that the L heads benefit A LOT from porting. Put in a couple grand on porting and looks like you're estimating 7 hp and 7 lb ft return. Same on the camshaft itself. If going with .060" more lift nets you 7 hp, I think the larger cam profile is leaving something to be desired. As to the original question of which cam to use, I think .480 is right in that zone where you have to do the work anyway (needs different valve springs and retainers and stem seals to prevent coil bind and prevent the retainer hitting the seal). If you're going that far, I'd spring for the bigger cam. And if those cams only have 5 hp peak difference between them, find a better larger cam.

Man, I feel bad for you Mark. Every dyno session, with the latest iteration of the motor anyway, has been a clusterfuck. I hope you get it sorted. I am pretty sure you're running the Porsche style CVs. I've heard of the bolts coming loose on quite a few different Datsuns. Might be a good idea to safety wire them. Could do the same with the driveshaft bolts too if you want.

We should have a betting pool. I can't remember if you have an air filter. If you do, I'd put my $5 on the stack second from the right making the most power by 2 hp.

I'm rubbing nickels together but should be able to get mine up and running again in a month or two. Have a bad master and need to replace the tires just due to age. Was carb tuning last time I ran it, too. Big problem for me is that I was way over the dB limit last time. I put Supertrapp tips on my mufflers, so hopefully I can just adjust it until it passes, but that might affect the carb tuning and all the rest. If I do get there, don't expect a lot is what I'm trying to say...

This looks like a question for ls1tech.com. From some quick reading, shorties are worth next to nothing compared to stock manifolds, big increases possible with long tubes.

The general answer to your question is "as far back as you can manage." John's Cars kit puts it at about 4". I moved mine further back, IIRC I'm at about an inch and a half on the pass head. It's not a simple thing. I had to cut the trans tunnel for clearance in front, and the 70 tunnel is narrow so I had to beat it with a BFH to make it fit. If I went further back I would have had to cut the tunnel in the rear too, or just cut the whole thing out and made my own, otherwise the bottom of the trans would have hung below the frame rails.

I think it's likely that the problem is sloppy CVs or splines on the CV shafts, but that said, there are quite a few other causes of diff clunking. I wouldn't count out every other possibility without at least checking the CVs for slop. If there isn't any, then maybe this post will help:

Yeah, that's pretty much it. Stockish Z suspension sucks. The Z was competitive in Street Prepared until the E36 came into that class. Again, I don't keep track of the classes I'm not in, but that seems to have been the end of it. They might have demoted it to a slower class by now but I haven't heard of the good news about its renewed competitiveness and I'm in enough groups that I think I would have heard.

Sounds like FP. You might fit in one of the street mod classes. They came about after I was already committed to Prepared so I never paid much attention.

Street Prepared.

Prepared class allows extensive engine mods. Can't do a stroker, but triple carbs or ITBs, huge cams, crankfire ignition, etc all allowed. L24/26/28s are allowed in SP too IIRC. In all likelihood people won't care if your car is legal for a class unless you're racing with SCCA (people who run events seem to be hall monitor types) or you start winning. Once you start winning they'll look closer.

You'll need interior to run in stock or street prepared. Z's suck in those classes, BTW. With no interior you'll be in Prepared. L6 will go in FP, where the Z is still competitive but not likely to win anytime soon and it takes a lot of money to build a competitive FP car, or with an engine swap you'll be in XP, where you won't be competitive at all. If you want to win, you've probably got the wrong car to start with. I just figure out who I'm close to in times and then run against those people and have fun.

Same. If you need a set of insulators I have some off of a 240 that sat since the mid 80s so should be low miles. PM me if you're interested.

I've got some thoughts about that roll bar design: 1. Don't like the X up high. Too much weight, and you're reinforcing the strut towers with the top of the tube where it isn't very stiff. 2. I would do the backstays to the top of the strut tower. Plate that whole trapezoidal area and weld the stays to the plate. 3. The bars in yellow are great if you are connecting to door bars on the other side of the main hoop. Without door bars I think it's just extra weight to carry around. 4. If you want an X, you can do it low, from the strut towers to the bottom of the hoop. I did this on mine. Would be MUCH easier to install if you cut out the storage cubbies. I didn't. 5. I'd just go with a straight bar across the strut towers EDIT--Also connect the top of the hoop to the map light area of the roof with a shear plate.

Heh. Looks familiar...

IMO you need to consider the usage to choose a ratio. If it's just a street car it probably doesn't matter that much, but for a car that does drag racing you're going to want to be winding out a gear as you cross the line. For my use, autocross, I figured I wanted to be able to do about 80 mph at the top of a gear. 23.5" tire I was using with 4.11 and T56 puts me at 81 mph in 3rd at redline. Just going to start in 2nd and not use first at all.

Searching "chassis stiffening" might get some better hits. Link below. https://www.google.com/search?q=chassis+stiffening+site%3Aforums.hybridz.org&oq=chassis+stiffening+site%3Aforums.hybridz.org&aqs=chrome..69i57.7719j0j4&sourceid=chrome&ie=UTF-8 For my $.02, if you're only doing a roll bar I would weld a shear plate from the top of the hoop to the map light bar on the chassis. Had a friend who built a really simple 4 point bar with an SCCA legal diagonal and shoulder bar on his 240. He said after he welded the plate to the map light area his rear interior plastic pieces stopped squeaking when he went in and out of driveways. Made a very noticeable difference. On my 70 I really thought the front of the car needed a lot of attention. I could jack up the front on the xmember, set jackstands under the TC buckets, and literally see the frame rails drooping when I let the jack down, and hear it all creaking too. The chassis is pretty flexible at the firewall, apparently. If you look at the old Bob Sharp pics (which you can find here) they spent some time reinforcing the area between the door hinges and the firewall, presumably to help that issue. There are also tubes that people run from the rockers to the upper frame rails. I think these kinds of mods are worthwhile if you don't want a full cage. It's what a triangulated strut tower setup is trying to do, but I don't think the triangulated bars are very effective unless you beef up the area of the cowl that you attach to, which almost nobody does (except bjhines). Another one to look at is the cage that Dan, 74_5.0L_Z, did on his. It's basically how you would cage a convertible with no windshield. I really think he did a good job for a streetable car, where you don't have to worry about hitting your head on the A pillar tubes. I did a full cage and my helmet rested on the halo. Had to move the seat towards the center, will also probably have to lower the seat more or use a 20* seat, as I have a 10* in there now.

No, they don't. Please take the information provided in the thread and disregard the rest. If you look you'll see that Alan can be helpful, as in the linked thread about the Bilsteins, when he wants to.