wheelman

A short update. I took the car to a local speed shop for a dyno day event, figured I'd get a baseline before the rebuild. The shop has a Dyno Dynamics unit, not sure how this compares to other brands but thought I'd add it so people know. The car put down 295 hp @ ~5000 rpm and 360 ft/lbs @ ~3300 rpm and was still making 250 hp and 200 ft/lbs at the rev limiter (6300 rpm). The engine is an LT1 from a retired 1995 Caprice cop car. I replaced the cam with an LT4 Hot Cam and the stock MAF with a larger one from a Camaro, it has a mail order tune on the stock PCM but I've "adjusted" it a little to accomodate the MAF. The fuel was nasty 87 octane pump gas. Based on these results I may go a different direction with the rebuild. Rather than attempting to increase the rpms I may just do a good quality build keeping the basic power curve as it is and learn to shift to 3rd gear on the higher speed auto-x courses.

Have you looked at the Corvette brackets? Using the Camaro or Caprice brackets with AC is impossible, the compressor wants to occupy the same space as the Datsun motor mount tower. Initially I fabbed up a bracket that replaced the PS and AC with pulleys that routed the belt correctly. Later I installed power steering so I modified the bracket to work as an AC delete.

That looks very nice Jon!!! It's gonna be fun getting the CV boot on those larger shafts but they certainly won't leak once in place. Xnke, I'd still like to see some pictures if you have them, all my information says that shafts from 90-95 Pathfinders are the same.

rsicard, I guess I shouldn't have said anything about 383 in the subject line of the thread, it implies thats what I'm building. I plan to use the stock crank (3.48" stroke), with a piston compression height of 1.26" the deck clearance is .025" if I don't mill the deck or I can take .020 off and have a .005" clearance. Does that sound right to you? I'm planning to stick with the heads I have (Iron LT1) and am currently running an LT4 hot cam with stock stamped rockers. The hp peaks at ~330 @5800rpm but hardly drops above that all the way to redline. I'm thinking its still above 300hp @6300rpm as it is and I plan to add 1.6:1 roller rockers.

I'd like to see how you set things up as I used a 92 Pathfinder front axle center section to assemble my drivers side axle and only needed a spacer about .6" thick, 1.6" doesn't seem right.

No, don't want to go to larger tires, the price for race tires rises pretty quickly as they get larger, besides I like the rims I currently run.

Michael, You're correct, my math is wrong, it turns out I have to use pistons with a compression height of 1.25" or 1.26". They're easily available so I'm thinking I'll go this route. I'm going to replace the stock powered metal rods anyway and go over size on the bore so might as well get a better rod/stroke ratio while I have it apart. ZFan1, This is not a 383 build and will never see "juice", strictly NA, so I'm not worried about the piston strength. I'm shooting more for higher rpm reliability than anything. With my curent gearing setup redline (6300 rpm) is at ~68mph in 2nd gear. I want to be able to run a little over 70mph without requiring a shift to 3rd, so redline needs to be >6500rpm. I already have high rev valve springs but don't trust the stock rods to handle 6500+ rpm very often. This is an auto-x car, thats why I'm trying to optimize the redline for 2nd gear operations. I normally shift to 2nd shortly after launch and stay in that gear for an entire run. Going to 3rd is an option but costs time and I'm not good at downshifts so reliably increasing the redline a bit is the goal.

I'm planning the rebuild my LT1 this winter and have an idea I want to bounce off you guys. I started looking for new rods as I want to build a bottom end that can handle higher rpm than the stock 95 LT1 and got to thinking it may be possible to build a long rod setup. Here is what I'm thinking: Get a set of "stroker" pistons meant to be used to build a 383, 3.75" stroke. Get a set of 6" connecting rods Run these parts with the stock crank that has a 3.48" stroke. My calculations are as follows: Stock stroke and rod length are 3.48" and 5.7" respectively, this gives a total length of 9.18" 383 stroke is 3.75 and rod length is 5.7", this gives a total length of 9.45" Stock stroke of 3.48" and a rod length of 6" gives 9.48" The combination I want to try is .030" longer than the 383 setup The stock parts provide a deck clearance of .017 which means this setup is .013 above the deck. A normal head gasket is .049" thick giving a piston to head clearance of .036" A set of 5.875" rods could be used and give a total length of 9.355" Using the 383 stroker pistons provides a deck clearance of .095" So, what do you guys think of these numbers and this idea?

It's been while since this conversation took place, figured I'd update the forum on how things have progressed. Here are the changes I've made in sequence and how the handling changed each time. All adjustments were run at the same track (Tri-City raceway, but different course configurations and weather conditions) Generally the track is a low grip surface, the weather ranged from warm to hot but always dry, Kumho V710 tires. 1. Cranked the shock settings to 2 turns from full soft. (This is almost full hard on these Konis) Handling didn't change significantly but the car did feel skittery and disconnected from the surface. 2. Increased tire pressures to John's recommended levels (26 front, 24 rear) The car was horrible with this setup, very loose, both front and rear. 3. Dropped pressures back to where I normally run them ( 22 front, 20 rear) and softened shocks to 1 turn front 1.5 turns rear Car back to how it handled before, slight understeer on sweepers, have to be careful on turn in of tight corners as it will push pretty bad. 4. Purchased and installed a set of adjustable TC rods from Brian (excellent design and quality, I highly recommend these). Adjusted to produce ~6* caster. (had to trim the front of the wheel wells to clear my tires. Huge difference on turn in of tight corners. Pivot cones are now my friend. Rear of car is a bit loose. 5. Adjusted front camber to as close to -3* as I can get, left is ~3*, right is closer to -2.8*, did not adjust rear camber. Front now sticks very well, understeer is gone but the rear is VERY loose. Spun off track into the dirt 3 times the day after making this change. 6. Adjusted rear camber to -2.5*. The rear is still a little loose but controllable, agressive throttle input will spin the car unless it's pointed straight. Turn in on tight corners is still great, no understeer detectable on sweepers. 7. Loosened rear sway bar. Car is very neutral with slight understeer in sweepers, tight corners are still very good. The car is easy to drive the way it is right now but turn in on all but very tight turns is a bit vague. I think I'll try switching to Hoosiers next year, I've heard they require less heat and I have a big problem getting enough heat into the Kumhos. I believe this is why the lower tire pressures seem to work better for me. I'm also going to continue experimenting with the rear sway bar and build a set of adjustable rear control arms so I can get the car squared up. There are still some lingering effects from when I wrecked it in 2007 that make it impossible to get it aligned exactly right. As Cary suggested I'll also be eliminating all poly bushings except inboard on the rear control arms. Hope this helps someone else get their suspension tuned.

Please don't think I'm saying these aren't a good design, far from it, but to imply they bolt in for every combination is not correct, thats why I posted in this thread.

Konis require the hole to be enlarged to clear the top of the strut, it extends further above the camber plate than the Tokicos and has a blade type adjuster rather than a screw. You could run Konis centered in the hole but then why use camber plates? As for unbolting the strut to make adjustments, at the track that would be a pain in the ass and you do make adjustments more often at the track than on the street.

I have a set of DP plates, you do have to enlarge the hole in the strut tower if you run any type of adjustable damping strut. Initially I ran the Tokico blues and had no problems fitting them without cutting the tower, recently I switched to Koni yellows and had to cut the holes in all 4 strut towers to clear the top of the strut.

The BMW LCA will not bolt up to the stock cross member (look at the diagram John posted on the previous page) but you might be able to use the BMW cross member.

The side view is very reminiscent of a 280ZX.

Never mind, Jon beat me to it.

Is this all 4, just the fronts or the rears? Thanks for the link to those TC rods, I really like the looks of them.

Thanks for the advice John, I'll try running a little higher tire pressures and see what happens. At first I was running pressures closer to those you listed but the grip is better at the lower pressures. The turn in is laggy as you put it but like I said I wanted the tires to roll all the way to the edge of the tread, maybe with the V710s rounded shoulder that shouldn't be as much of a consideration. I was thinking of using adjustable arms to get more camber because I'm using biscuit type plates and am at the max adjustment with them, guess it's time to switch to weld in plates and possibly modify the front strut towers in order to get as much camber as possible. Whats the best way to get caster adjustment? I don't like the Techno Toy adjustable TC arms because they move the pivot point, is that really a big deal, especially if the suspension range is reduced with stiffer springs? I tried running 1/8" toe out and felt like the inner tire was scrubbing real bad in tight turns, maybe I'm suffering from bump steer in the system caused by the power steering swap I did. I really need to measure that and see just how bad it is. Anyway I set the toe back to about 0 and it worked better, something else to play with. Toe in the rear is about what you stated, close to stock. From your comment about the ride height I get the impression there should be a slight rake front to back, ~1/2" higher in the rear. I'm close to 1/4" right now, I'll add another 1/4" before the next event and see if Ican even feel a difference. Any suggestions on how to set the rebound dampening on the Konis? They are at full soft right now. Just an added piece of information, the surface I race on most frequently is relatively low grip. It's an old roundy-round tri-oval that used polished river rock in the asphalt when it was laid. This rock now makes up a large portion of the surface as the tar component has partly worn away. I'll make sure to only change 1 variable at a time when I do adjustments.

This last winter I made major upgrades to the suspension of the Z and now it's developed a mild case of understeer. I want to run some ideas for tweaks past you guys, see what you think. First, here is the current setup. 350lbs/in springs front 325lbs/in springs rear Koni Yellows, at softest rebound dampening front and rear MSA anti-roll bar set 1" front, 7/8" rear. Energy suspension poly bushings every where there is a bushing R200, 3:54 CLSD 1" roll center spacers -2 degrees front camber (have to use adjustable LCAs to get more) -1.5 degrees rear camber +3.5 degrees caster ~0 toe in front and close to stock in the rear. Stock control arms (for now) ride height about 4" at frame rail, basically level front to rear, at least as much I can tell. sectioned strut tubes (not hitting bump stops) New Kumho V710s, 265/45-16, 22psi front, 20psi rear The car's weight distribution is about 52/48. The goal is to get the car to a more neutral/free setup This is for auto-x, not high speed, lots of quick transitions Here are my ideas 1. Move the heavier springs to the rear. 2. Raise the rear ride height (already raised it 1/4" which helped some) 3. Run more rebound dampening in the rear 4. Use adjustable LCAs in the front to get more negative camber 5. Remove camber from the rear 6. Play with tire pressures I don't really want to as the pressures I'm running are to get the tires to roll over all the way to the edge of the tread, big tires on a light car. Tried going lower in the front but turn-in became vague. The understeer is not horrible, this is more of a fine tuning exercise than anything. The car puts power down very well exiting elements but will push if I apply too much mid-corner, I'd rather it rotate a bit instead. This is why I'm thinking the heavier springs may work better in the rear, there's not a lot of difference between them, it would soften the front a little and at the same time stiffen the rear. I also have a set of 250lbs/in and 225lbs/in springs I took off. Feel free to ask questions and make suggestions. Future plans are to add adjustable control arms to the front and rear, a splitter and most likely a wing for higher speed stability.

Jon, I've been thinking about this and one more thing should be made clear. If someone decides to use the drivers side 300ZXT axle on the passenger side they will still need to completely disassemble it in order to use the correct inner CV joint. The "stock" passenger side axle is the one with the longer splined section that inserts into the diff, this CV must stay on the passenger side of the car.

Yes, definitely go for it!! The racing is good and generally close with a little bumping and grinding to keep it interesting. It's not like F1 where it's turned into the Sebastian Vettle show and gimmicks are used to encourage passing. I agree with gogriz91, the GT series is more interesting the the DP series, especially this year with the Ganassi boys winning most of the races.

There isn't a passenger vs driver side length difference in the Pathfinder axles. These are front axles BTW, there is a central diff/axle unit that has an extension to one side, this makes both CV sections the same length. EDIT: Ask for 90-92 V6 4x4 Pathfinder front axles. I asked for 1990 units but ended up getting one from a 92 that had the tripod joint on one end. It will work as the splines on both ends are the same size as those on the 300ZXT shafts. I don't know whether the shafts are the same in following years so if you get a 93 or later axle it may not be what you want. I paid $50.00 for the pair so it's not a big deal that I only used one of them, leaves me a spare.

Which Pathy axle are you asking about, the one I ended up using or the one with the tripod joint? Both of the Pathy axles I bought were the same length, I didn't use the one with the tripod joint because I initially thought the JY had given me a 4-Cyl unit.

Jon, I'm having a hard time making your numbers work. Even in the best case the original passenger side shouldn't have fit at all. 15.875" = length of passenger shaft 1.25" = 1 spline length 1.687" = depth of CV housing. Available length = 12" according to your measurements 15.875" - 1.25" - 1.687" = 12.938" 12.938" - 12" = .938" I used 1 spline length because the outer splines protrude through the cage and it's actually the end of the shaft that contacts the cap on the outer CV housing when the cage is flipped. Based on these numbers the original passenger side shaft should be .938" too long to fit at full bump which according to your numbers is the best case. Doing the same thing with the drivers side shaft yields these results. 15.375" = length of driver shaft 1.25" = 1 spline length 1.687" = depth of CV housing. Available length = 12" according to your measurements 15.375" - 1.25" - 1.687" = 12.438" 12.438" - 12" = .438" This indicates the drivers shaft would be almost 1/2" to long, this is obviously not the case as I was able to install mine and actually move the shaft back and forth at full droop. If you look at the pictures I posted in this thread http://forums.hybridz.org/index.php/topic/72805-using-pathfinder-and-zxt-axles-to-install-30-spline-nismo-lsd-kit-56k/page__st__40 you'll see the outer CV housing is actually closer to 3" in depth. Using that value instead illustrates how much space is available. Here are the numbers for the drivers shaft 15.375" - 1.25" - 3" = 11.125" 11.125" - 12" = -.875" In other words there is actually closer to 7/8" of clearance at full bump and 1/2" at full droop. This would imply the passenger shaft would slightly bind at full droop, have 3/16" clearance at mid point and have 3/8" of clearance at full bump. These numbers fit what I experienced. I run the welded flanges and my passenger axle was slightly bound up at mid-point until I cut 1/8" off the end of it and ran about 0* camber. I looked at your numbers again, think I found the mistake that was confusing me. You used 2.125 instead of 2.5 to account for the spline length. Correcting this makes the following equation: 11.635 + 2.5 + 1.6875 = 15.8125 15.8125 - 15.375 = .4375 So your numbers look very close to mine assuming the outer CV cage is not flipped.

According to the compressor maps I found the CFM for a standard T3 60-trim is ~428. A 50-trim is ~357 and a super 60 is ~464. Here is the site where I found the maps: Turbo and Supercharger maps I'm not 100% sure but I believe the stock T3 was equivalent to the 50-trim so you should gain about 100cfm. What type of power band are you looking for? The T28 exhaust housing might be a bit small if you want a high revving motor, you might be happier with a T3/T4 hybrid of some sort.

It's mostly due to the additional torque the 3.7:1 ratio transmits to the wheels. The shorty headers may have gained you a few HP but not so much that it would be noticeably easier to spin the tires. You might be better off mating that Torsen to the 3.54:1 gears, you'd be back at the ratio you were happier with and have the LSD.