Afshin

So no one else has an opinion on this ? Do you agree with Nathan that practically speaking length doesn't matter (the consensus always seems to be girth as the most important) I figured that it will be easier to have a long air filter to AFM intake that to have a long intercooler pipe which is harder to make because o f need to sustain pressure without any leaks. Don't want to blow out to early now, no debate regarding this issue, you got keep it up man (i'm refering to the boost off course) No seriously, does anyone else have any experience with this ? If not I may just take Nathan's educated guess and go ahead with the long pre-AFM intake.

OK, I think I may have figured out the confusion here. First to be clear, MPFI is superior to SPFI. It is more efficient and produces more power. This is fact, even the 5.7 l chevy motors output jumped significantly when they switched from SPFI to MPFI. Read any technical article and you will see it clearly described. Also when I was referring to racecars using MPFI, I was referring to formula 1 and Le Mans type of multimillion-dollar cars. Ferrari Enzo (redline 8500), Honda S2000 (redline 9000), Porsche carrera GT (rival to Enzo) redline 8000, Modena, new ford GT40…..all use MPFI because it is better, provides more power and sustains high RPM’s reliably. As Jon mentioned, the only benefit of SPFI is lower cost. The problem you guys are referring to relates to chevy’s factory TPI (tuned port injection) or even Fords factory set up where they used long narrow intakes runners and set up the cars for high low end torque. This was to make the factory heavy automatic car fun to drive. This worked well but the cars did not breathe well over 4500 RPM. The long narrow intakes they used increased low end torque (high velocity and high momentum creating high pressure at the intake valve), however they minimize flow because they are long and narrow, which limits high rpm performance. As such people with moded cars/engine have to switch the intakes for better flowing ones and then EFI for further gain (still MPFI as long as you were not broke). Also post 1990 EFI setups using MAP sensors can not accommodate much customization since they can’t account for differences in vacuum or anything that affects factory-assumed relationship between manifold pressure, engine speed and engine air flow like MAS/AFM can (to a certain point off course), hence they perform poorly when you change cams, intake manifolds.. if the PROM is not remapped. Again, none of this has anything to do with MPFI vs SPFI. I hope this helps.

Hi Nic. I went back and dusted off my F.I. book by Jeff Hartman and he clearly states what I already wrote earlier that the fuel has the tendency to collect on the intake walls causing droplets (otherwise the increase distance would make for better atomization). Also he said that since that designing the intake for equal airflow does not make for equal air/fuel delivery. The reason is that the dynamics for the fluid and air are different (heavier fuel tends to gravitate to the outside of the manifold bend) and hence you get uneven air fuel mixture in the different cylinders. Also Edelbrock's co. claims 30hp and 40 ftlb torque gain on a 5.7 liter chevy motor when switching to MPFI. Also Holley pro injection on their tech info page clearly say the MPFI provides better performance and economy over SPFI and that direct injection is the best. Again, all the cheap penny pinching manufacturers spend a lot more money using MPFI over SPFI because it is more efficient. There is no question about that. No professional race car, ferrari... or any car that I'm aware of use SPFI. As far as I can remember they were used early on when the companies were too cheap to switch from carburetion to MFPI, so they went with a hybrid which is the SPFI. I don't know what the LS1 drivers are talking about, I can certainly be missing an important point. However I can't see the MPFI which is used by all race cars running out of breath at high RPM compare to the SPFI.

36 at my last birthday, 36 at my next birthday....

From my understanding, this is incorrect. The reason that manufacturers spends the extra money to make MPFI over SPFI is that by atomizing the fuel into the air stream closer to the combustion chamber the fuel stays atomized. The primary problem with SPFI is that the fuel is atomized far away and they collects against the intake manifold walls causing droplets. This then leads to inconsistent air fuel mixture.. With the high fuel pressure you don't need that much distance to get full atomization and as distance increases you get droplets forming = less atomization and less consistency, efficiency, power and mileage.... The next wave is direct injection into the combustion chamber(used mostly in diesel for now). Also you can control the injector pulse to match the intake valve opening (not that the stock system does that) allowing for atomization at the right time for each cylinder as opposed to spraying during all cycles which would again maintain better atomiztion. Can't achieve that with SPFI I would expect the opposite for the reasons mentioned above

Does anyone know how far or long can the tubing between the air filter and the AFM be? Can I use a long 3-3.5" tube from the AFM (keeping the AFM in it's original location) to run across the radiator and have the air filter on the right side? The reason would be to make room for the intercooler piping(shorter pipe and less bends = less lag). My initial thought is that it should not be done and that the pressure/flow across the distance would be too much and impede air flow. Is this assumption correct ? Does anyone have any experience with this? Thanks

I just popped in the g machine adjustable camber front control bushings. However, looking at them more closely, I'm concerned about potential quick wearing of the delrin bushing (the plastic bushing pivots around an aluminum sleeve, so I'm afraid the platic/delrin will wear quickly). Does anyone know anything about the longevity/reliabilty of these unit? If advisable, I rather buy non adjustable poly bushings and swap them now while the suspension is still apart. I don't have to have adjustable camber, as my current setting is fair. However, it's not perfect and I certainly would like to be able to fine tune it some more. Also my Santa Z parts wish list is already way too long so I can't buy adjustable camber plates Thanks

If your fuel delivery is not maxed out then the EFI will adjust appropriately for the cloder/denser air. And since the cooler air is less prone to detonation, you can actually turn up the boost without any detonation. When I had my old 280z turbo and another 280zxt on the east coast, both non-intercooled, I could turn boost up 1-2 lbs in the winter over the summer time. Only if your fuel delivery is maxed out at your current boost, could you possibly get more detonation because of leaning out. If your car is detonating when it is cooler, it most likely a prbolem with your EFI, such as non functioning temperature sensor causing the problem.

Thanks, I appreciate the diagrams, it will save me much time.

Hey fly327, you still owe me a test drive. Bring the car by this week, I'll be gentle I guess my car is next, I have a 300zx ecu and AMS collecting dust in the garage. It should be quick since you just did yours (beer and pizza on me).

As Jon said there is a kit MSA sells. It allows up to 1.5 degree of rear camber and up to .75 deg of toe adjustment. I just got the kit last week and it looks nice (have not installed it yet). I know the kit works, but you can't always change both the camber and toe fully independent of each other. JeffP use the same kit on his monster 280ZXT and is happy with it, here is a link to his setup including a picture of the kit assembled on the car. http://www.angelfire.com/extreme/280zxt/page17.html This along with new rear poly bushings should do wonders to correct the toe (which is often off in the ZX), specially under load and eliminate the excessive play in the ZX's rear semi-trailing arm set up.

tom sixbey wrote Yup. I already have the G-machine kit, so I will be using it along with the bumpsteer spacers I got on ebay. This should take of the problem. However the set up that Mikelly suggested is still better. I already have the G-machine set up so I will do that instead for now and will switch to a full rod end set up when the g machine platic ball starts to wear. I also got new adjustable control arm bushing (allows for camber adjustment) to replace my old stock ones. Can't wait to get the car back on the road DatsunATX wrote Wow, I'm glad that didn't happen to me. However, I think more likely than the rod digging into the ground, the control arm and wheel moved back hitting the chassis, stopping the wheel and flipping the car over.

Hi Cody. I used to have a l28ET hybrid Z before and another 280zxt , and never had the TC rods fail. That's why I originally started this post to see if it was a freak accident or an actual problem. Considering the amount of other members with broken TC rods, and after looking at the suspension more closely, I now consider it a "real" problem. Off course all TC rods are not going to fail, but even one in 20 is way too many (it seems to happen more with the 280ZX than the Z). Also you were using the G-machine set up which would take care of the problem since you did not have the 2 stiff poly bushings limiting the rods range of motion. I think the shot peening is also a good idea. Thanks for all the info Mike.

Hi Mike, I just found the pictures of your adjustable control arm and TC rod end set up for the Z in the spring 2002 sportZ mag. They look absolutely great. I have a question, the adapter that bolts on the chassis point, did you custom make it ? or can I buy it along with a spherical rod end which I could them customize/thread to the factory TC rod?

Hi Chris and ZR8ED, my experience was the same as yours, I heard a thump under the car, and then when I hit the brakes whoa! it pulled to the left like made. I looked further into the MSA (made by G machine) kit. Interestingly the same part is listed for both the Z and ZX in the VB catalogue (same part number) but in MSA is only listed for the Z. I guess it's working fine on Chris's Zx as well as the 510's. SO my final plan is to order the kit tomorrow, use stock bushing on the other side and put on the bump steer spacer to correct the angle. I think That should take care of the problem. It will greatly reduce any play, provide a pivot point with good range of motion and still have some (not much) vibration/shock dampening from the one bushing. The only down side as Jon mentioned will be shorter life span for the plastic socket, but it's cheap, easy to replace and Jon's looked OK after 30K miles. I could not find anyone making an adjustable rod end bar. But I found a site that sells the rod end, which I guess you could put on the stock rod after shortening it and threading it for the new adjustable rod end to go over (probably what Mike had in mind). http://mdmetric.com/rodend/homepag2.htm However this is much more work and would also involve modifying the chasis mount for inserting the bolt that would hold the rod end in place (actually not hard to do, just drill a hole on the side of hte factory mount plate, there is a nice picture of one on Jeff P's website). http://www.angelfire.com/extreme/280zxt/page20.html

Well I took my control arms and TC rods off today and took a nice look at everything. As you can see in the new picture the TC rod does not align with the chassis mount. However, a bump steer spacer by going below the strut housing and on top of the control arm not only corrects the tie rod/steering rack angle but does corrects the TC rod angle. So that problem will be taken care of. I then checked the range of movement for the rod with the poly bushings. It is absolutely terrible. No wonder it broke. I have been thinking about making custom rod ends vs trying the MSA/G machine kit. Considering that the kit works on the 510 and that the Z and ZX use the same bushings, I think the kit should work on the ZX (easier that making my own adjustable rod end bar). Replacing a stiff bushing for a pivot point will greatly improve things, I can then use a stock bushing on the non-load bearing side. I guess everyone should consider using bump steer spacers on lowered Z and ZX’s for both bump steer and correcting TC rod angle. After looking at the ZX set up closer, I strongly recommend against using two poly bushings without further customization/precautions, at least on any 280zx. [/img]

I just added two more pictures. If you look carefully at the bushing washer you can see that it is angled, there is space at the bottom between the washer and the bushing, and it is compressed at the top. Again this shows that with the lowered suspension on the ZX and poly bushings there is continuous load on the side/wrong axis of the TC rod.

I posted some pice in the scary tension rod failur post

Well this is my first picture post, Iguess I need to downsize a little more. As you can see the rod snapped at the end of the metal sleeve that fit over the rod, so that was the pressure point. It's hard to see in the picture, but the angle that the rod is pointing to is a little off from the center of the mount. That placed a steady pressure/deflection stress on the rod which greatly increased the rate at which the rod developed fatigue and hence failure. In other words the hard poly bushing was always placing torque on the rod, not just during suspension compression. Also the amount of torque will only be that much higher during suspension compression than if it were starting from the factory non-lowered angle. If the bushing was softer it would have not applied enough pressure to snap the rod. [/img]

Wow! that's one hell of a event. Nice job with the landing, glad you did not get hurt. The fact that the car also seems moslty OK after such an bad event is icing on the cake. So what color? hummmm on of the nicest Z's i saw was one with a clean stock bodied corvett yellow paint (I saw one two other yellow ones, but there were so so, one yellow had a hint of green in it (blah)and the other had a hint of creamy white). I thought it might look cheesy when my cousin told he would paint it yellow, but man was it nice. What colors are you considering?

The rod broke right where it enters the first bushing. i will take a picture tomorrow and see if I can figure out how to post it. It looks interesting.

Hi JC, I was looking forward to some input from you. In the parallel post you said: Well I’m certainly aware now that putting on poly TC rod bushings on a lowered car is an improper modification. Unfortunately I was unaware of it and never heard of any warnings prior to this. As far as inspection, the TC rods were inspected 10 months ago when I installed the new bushings, the car gets frequent alignment checks and is within specs (except for rear toe being slightly off, I will get adjustable bushings for that). I'm very cautious with my car and always use good quality new components. This failure made me nervous because I thought I was being careful with my mods and frequent inspections and still never saw it coming. What I'm trying to figure out now is how to fully fix this, while maintaining a "tight suspension". I don't like addressing the same problem twice and I definitely don't want to risk the same critical failure twice. I drive the car on mountain twisties all the time. Again the suspension was just inspected so I don't know how to prevent this. I don't know if a lowered 280zx places more deflective force from the bushing on the rod as opposed to Z(?different angle). Also my car has relatively low mileage and was bone stock until two years ago when I bought from a non-aggressive slow driver. So there wasn't much chance for long term suspension abuse and the poly bushings were on for only 10 months.Thanks again for everyone’s useful comments and advice.

OK, I agree with Jon, Pete and Terry the spacer is a bad idea and hence dead. Yes it is. I don't know why the kit is not listed for the 280zx. the Z, ZX and 510 use the exacte same TC rod bushings. The ZX and 510 have very similar set ups, same rear control arms bushings and same bump steer spacers... Does anyone know anything more about this? I will try looking into some more since it would be a nice and simple solution. If memory serves me correctly Jeff P had made custom TC with rod ends for his ZXT, I guess I will try emailing him.

I have a 280ZXT, the TC rod mounts below the control arm. Also I looked under the car and clearly the bushing is compressing on the rod because of the change in angle from lowering the car. So a spacer by correcting the angle will center the TC rod to the mounting point on the chassis and decrease the torque applied by the bushing, which was responsible for the rod failure. It should not increase stress on the rod. However, i agree with jon's concern about bolt failure from the increased stress caused by a spacer. No point in preventing the rod from snapping in two to only come off the control arm. Unfortunately for me, the MSA/G machine kit does not fit the ZX (damn I hate that) and I have not seen any adjustable TC rods with pivot rod ends as opposed to bushings for my car. Also does anyone know of a custom TC rod for the 280ZXT. We can't all be just engine donors I can certainly use more opinions/experiences, ideas.....thanks

Hi Juan and blueovalz. I wrote a new reply in the scary tension rod failure post Take a look if you can, I would appreciate your input.