Pyro

One 76 turbo Z One 78 Z (just cam and compression upgrade) One 71 V8 Z that I haven't run in awhile due to the other cars needing work. But here are the V8 performance specs 60 ft: 1.5 seconds 1/8 mile: 6.9 at 110 mph with 175 hp shot n20 1/4 mile: 10.7 at 135 mph with 175 hp shot n20 1/4 mile 11.7 at 120 mph all motor ENGINE 11.0:1 cr, 362 cid sbc (+0.030 bore, +0.070 stroke) Dart iron eagles, stock 200cc full length headers with 2.5 inch exhaust CompCam 292H Edelbrock performer rpm intake with 750 holley vac sec Drivetrain T5 GM 5 spd with 10.5" 6 puck sintered iron clutch on 153 tooth flywheel Hays scatter shield bell housing stock R200 diff, stock 1/2 stafts and axles (short lived parts) centerline wheels, 15x6 fronts, 15x8 rears with MT drag slicks brake line lock Other stuff 10 gallon fuel cell Mallory fuel pumps msd hei conversion stock Gm radiator with black magic fan frame rail re-enforced lowered 2 inches with heavy rear springs and light fronts autometer white faced gages (5" speedo and tach) Need a 9 inch rear axle and roll cage very badly!

I never had an angle plugged head but I hear they have a lot more problems when it comes to header fitment. Most headers for sbc's are designed for straight plugs. I would get a straight plug head just for that reason.

JTR manual says mid 14's at 95 mph with a 185hp 350 (4bl, stock manifolds, single exhaust, stock cam). That is an engine similar to a goodwrench 350 replacement engine. It will drop time quickly with a cam, headers, intake, carb, and aftermarket heads.

15 degrees initial titming sounds about right. But maybe a little more total advance, 34 total. Yes, adjust that carb. But one of these days plan on getting a regular old Holley. The Holley 3310 750cfm vac. sec. carb is the best bang for the buck carb ever made. For better performance, consider a cam change. And get a cam with 108 to 110 lobe seperation (good for a carb) and look for a cam with steeper ramps. The CompCam hydraulic rollers XR282HR or XR276HR look like much better performers than what you have now (10 to 15 degrees more duration at 0.050" with the same advertised duration). However, your current cam should give decent power with a good idle, good mpg, and a long service life which is nice. Plus it is already paided for, right! I tried a 700R in my Z and didn't like it. I ended up using a GM T5. It will hold the power as long as you shift a little slower. I ran 10's with a regular T5! Good luck with the engine tune!

It is funny how these cars get faster and faster. I didn't intend on making a 10 second 130+ Zcar from the start of the project. It just kind of developed into one over the years with small improvements each time. I have been down the track a 100 times over a 3 year period while making small gains every time. Started out just running high 12's at 110 mph then it got out of hand. That is why I never got around to a roll cage or a straight axle. It is time to detune the engine or install a cage and a proper diff. At this point, detuning sounds much easier. I guess I'm getting too old. hahaha

Those are wierd cam specs. 275/280 with only 208/212 duration at 0.050". Normally a cam with that much advertised duration would have at least 230 degrees at 0.050". I guess that is a factory GM grind with very slow ramps. Is that the cam that came in the ZZ4 block? The 112 degree lobe center is also hurting throttle response a little since you have a carb. But, that cam is pretty small when considering the at 0.050" duration. So, I think your timing is about right. You could try 15 initial timing to see if that helps the low rpm torque. 20 maybe be too much from that cam. But on the other hand, the advertised duration (275/280) normally would run well with 20 degrees initial. The low duration at 0.050 is throwing me off. Where are you getting those timing recommendations from? I limit the total advance in HEI's by placing some weld in one of the advance slots to shorten the travel. You will need to disassemble the distributor to get to the advance slots to weld them. I weld a little in one slot then grind it smooth and flat. The vacuum advance can also be reduced with the kit that you have already found. That vaccum advance kit uses a stop plate and a controlled vacuum leak to make a custom vacuum advance profile but it doesn't limit the advance from the mechanical portion of the distributor. Newer head designs (fast burn and vortecs) don't require as much total timing as the older style heads. So, in most cases there is too much total advance when older style hei's are used on newer style engines. That is why the length of the advance slots should be reduced.

Great runs! I only get about 10 passes with the stock Z stuff and were running about the same times (10.6 at 135). Stub axles shearing, spider gear failures, u-joint breakage, ect. So, don't expect it to last long. With power that, we both need a ford nine inch straight axle conversion and a full cage! Besides I'm tried of replacing broken stuff and feel lucky nothing ever broke at high speeds. I can't go back to the track either without a cage. hahaha

A cam with more than 220 degrees of duration at 0.050" lift really likes a lot more initial timing. Your cam sounds bigger than that. 20 degrees initial is very common setup with bigger cams. However, more initial timing will also add to the total timing which is not a good thing. That is why one of the advance slots in the HEI need to be shortened to limit total timing to 35 or so. You need a timing light with a degree knob on the back or use degree tape on the balancer to determine total timing. Also, big cams with low (stock) timing makes the headers glow red. No, 20 degrees will not hurt anything. I run 20 on my sbc engine with a 242 degrees of duration at 0.050". 20 degrees is recommended in "how to modifiy sbc books". BTW, that is the factory timing for a L28et. Wider lobe separation will make a carbed engine feel sluggish. Cam overlap helps the carb fill the cylinder with fuel. 108 to 110 is about ideal for a carbed street engine, 112 is getting too big, and 114 is weak. EFI does better with wider centers (112 to 114). Where is the vacuum advance connected? It should be on the ported vacuum source on the carb. The ported source has no vacuum on it at idle. You should set the timing without the vacuum advance connected. And little to no change should occure to the timing when the vacuum advance is connected to the ported source. If you have the vacuum advance on manifold vacuum then the timing will retard when the throttle is opened which will reduce off idle torque.

What is the cam duration and lobe separation? Yes, a stock converter can make a big cammed engine a dog at low rpms. What is your initial ignition timing at? Are you using the vacuum advance? What is the total timing? Bigger cams need more initial ignition timing. Try 20 degree initial. Then the vortex heads don't need much total advance because of their fast burn design. The total timing should be about 35 degrees. You may need to weld up some of the advance slot in the HEI to get a curve like that (15 degrees of advance). Then use a medium light springs on the advance weights. Mr. Gasket sales a recurve kit for the hei, but don't use their weights because they get stuck. Use the factory advance weights with the medium Mr. Gasket springs. Edlebrock carbs suck. You should get a Holley or get a Q-jet.

I would guess a regular height team-G would fit. I believe there are three different team-G's for the sbc, all of various heights. The taller the team-G intake, the higher the power band. However, I like the performer rpm better for all around performance. It has good low rpm power and pulls hard to valve float (7200 rpm). There is a Z club in SA, but I have never been to one of their meetings. I hear they meet once a month at a local burger joint (Chesters). Something like the first Tuesday of each month.???? A few friends of mine have Z's and I have three of them myself so we kind of have our own little Z club at my house. I'm too busy just trying to get all my cars into shape, fixing up my old house, helping out with my new baby boy, and other family matters. I'm just lucky to spend a few hours a day out in the garage working on Z's and drinking a few beers. So, no car club for me for awhile.

I have a JTR V8 install on a 240 with a stock hood. And a regular Performer RPM with a 1/8" thick throttle cable plate under a Holley 750 carb (3310) and a drop base air cleaner with 2 inch air clearner, barely fits. I get a little paint clipping under the hood because of the air cleaner stud. That is close! I have the complete JTR install which includes the 0.5" spacers between the body and the front crossmember. This gives a little more carb space. I drilled and tapped 4 holes in the intake (under the carb) for N20 foggers. Then mounted a 1 gallon fuel cell and Mallory comp70 pump by the radiator for the N20. Then ran racing fuel in the 1 gallon tank. 1 gallon of fuel would last 1 30lb bottle of N20 with a 175hp shot. I couldn't use a N20 plate with the RPM intake because there was not enough room. I did try a short team-G intake, single plane and it did fit with a 1" N20 plate.

I guess you just need to re-dyno it without that bad muffler. I bet the torque picks up.

Well after reading you post a little closer it seems your traction is good. Sorry for getting on the subject of tires. I think you need to find your ideal take off rpm. Before you go to the track find a quiet street with no houses near by. Then do a fairly quick clutch and throttle drop at 3000 rpms and see what happens. If it doesn't spin the tires then go up in 200 rpm increments until it blows the tires away. This will get you a range for a take off rpm. A little to moderate wheel spin is ok and the engine should be on boost quickly if you are going to make a good 60 foot time. Then try delaying the throttle drop by 0.5 second after the clutch drop. Try to come up with a simple technique because at the track, simple is best. If the boost just breaks the tires loose real hard then plan on doing some suspension work, installing a lsd, and getting a set of wheels with slicks just for track day. Otherwise just concentrate on getting a high mph. Yes, getting a good MPH is also an important feature of drag racing, especially in a street car that is not good at running quick et's due to bad traction off the line. Make sure to stay out of the water box at the starting line. But do a little burnout to clean off your tires. Radial tires get there best traction at maximum air pressure, so check your air pressure. I was looking at my old time slips and I also had a hard time running good 60 foots in my turbo car: 2.142, 2.387, 2.306, 2.532, 2.371, 2.515, 2.306. The boost would come on and the tires would just spin! My car would run between 13.6' and 13.7s from 106 to 108mph. My 240 V8 zcar with N20 ran 1.5's 60 footers all day long. And all I had to do was side step the clutch at 5000 rpm and push the gas pedal to the floor. It felt like the front tires were lifting! Slicks, no front sway bar, stiff rear and soft front springs was my only real mods. I'm not the best driver off the line either but if the car has traction and torque it doesn't matter. But I can tell you that 1.5 60 footers feel fantastic! That was most of the fun of the entire drag race. However stopping an old Z going 135mph at the end of a short track wasn't. Hahahaha

I wouldn't even go with old hard tires. Nothing more frustating than no traction off the line when at the drags. Wait until you get new rubber on the rear wheels before you go. Fresh rubber, even if it is cheap rubber, will make a huge difference. In the early evening, the traction on the track is worse than on the street! The starting line doesn't get sticky until a bunch of cars lay down fresh rubber which typically takes until 9 or 10 at night. At least wait until then before running it. Try removing the front sway bar for better weight transfer. Good luck.

Legally a turbo counts as one muffler. That is how the new dodge srt4 gets by without a muffler. One turbo and one cat is all it has, but it is loud. Blower cams are different than turbo cams, right? Turbo cams normally have more intake duration than exhaust and blower cams have more exhaust duration than intake. However, both cams should have very wide lobe centers. I use hooker Aero-Chambers on my V8 Z and they are pretty quiet while driving down the road but are kind of loud at idle.

The turbo intake has the pcv port in a position as not to hit the turbo. It can be moved on the NA intake but just simpler to use a turbo intake. I just didn't feel like writting anymore so I didn't go into detail about that. So, yes a NA intake can be used if the pcv port is moved. Sure you can run 550cc injectors if you use an aftermarket efi computer. Yes, a thicker gasket will lower compession. However, 8.3:1 can be turbo charged with an aftermarket efi system with ignition control if low boost is used. I just prefer higher boost and 7.4:1 cr.

Can be done, especially with lower boost. I had good luck with the stock NA efi system by just locking the ignition timing advance and using a FMU to increase fuel pressure during boost. Runs great but the mpg is poor. 9 to 12 mpg in the city, 16 to 22 on the highway depending how I drive. But the cost of an fmu (200.00) could be applied to the cost of an aftermarket efi which is the better way of doing it. You could also lower engine cr with a head swap since the 75 to 80 Z/Zx engines already have dished pistons. Use a P79 or P90 head to get to the stock turbo cr (7.4:1). Lower compression is safer to use. You will need a turbo oil pan, turbo exhaust and intake manifold, stock turbo with wastegate and down pipe, oil feed line and tee, oil drain line, turbo oil pump, and J-pipe. And as mention already, a complete turbo engine maybe a better way to go. Then the stock clutch is not really up to the task. You should also upgrade to a 2+2 clutch (240mm).

Maybe the material is different on the turbo pistons, but I don't really see a reason why the nissan engineers would go through so much trouble for a 7.4:1 cr engine with only 7 psi of boost. Not exactly a high output situation. I could be wrong but I feel all the factory L28 pistons are made of about the same stuff. If anything, the aftermarket pistons are most likely a cheaper/weaker material as compared to the factory.

The top ring is thinner on the 81 to 83 L28 pistons as compared to the 75 to 80 L28. The lower rings are the same. 81 to 83 pistons (turbo and non-turbo) have the same ring thickness at the top and bottom.

Twin t3's mostly like would be maxed out at 2 x 168cid, or 336 cid. Maybe ok for 390 cid for a low rpm (4500rpm) and low boost (5 to 7 psi) application.

I run between 13 and 15 psi with the stock turbo pistons and P90 head and haven't had any problems. I feel the datsun L28 is prone to detonate as compared to more modern engines. Nissan engineers set the compression ratio to 7.4:1 with 7 psi of boost for a reason and I feel jacking the boost up to 14 or 15 psi is pushing the stock design enough. Using the NA compression ratio with double the factory boost level is asking for trouble. It is like sleeping with both sisters, I'm not saying it can't be done, but needs to be done very carefully. hahaha I would pick one or the other: Stock cr with more boost, or more cr and stock boost.

I vote for a fuel ratio issue or wastegate oppening problem. I had the same problem until I applied some positive boost pressure on the atmosphere pressure side of the wastegate. Not sure what wastegate you have. But on my external delta wastegate, by using a lighter spring then appling a reduced and regulated boost pressure on the vented side of the diaphragm, the boost would come at the same rpms in all gears. So for example, a 9 lb wastgate spring with 4 psi on the atmosphere side of the wastgate will make 13 psi of boost. The 4 psi is made from manifold pressure that is regulated down to 4 psi. You could try a first and second gear run without the boost line to the wastegate to see if this might be the problem. If the boost comes up in first gear like it does in 4th, then you need to do something to that wastgate. But, be careful not to over boost.

Seems like good power to me! Could be the stock cam is done at 4500 or the valve springs are a little weak. Maybe a some 0.020" thick valve springs shims under the outer springs and a tighter lash would give you a few hundred more rpms. Wow! 275hp at 18 psi of boost. Who would have guessed that?

At 15 psi........ 255 hp @ 5000 rpm with stock cam and stock head, 300 hp @ 6000 rpm with MSA stage I turbo cam. 330 hp @ 6500 rpm with MSA stage II turbo cam. rpms make a big difference in power output and a bigger cam is needed for that. up it another 5% with a little head work. 270hp, 315hp, 345hp. try this site to predict hp from a turbo: http://www.turbofast.com.au/tfcalc.html

A 350 will make more power than a 327 if all the same stuff is used. Why give up power? It is harder to build compression with a 327 due to the smaller displacement. Dome pistons must be used to get over 9:1 on a 327 with todays smallest combustion chambered high performance heads. Todays high performance aftermarket is aimed at 350 and larger engines. It is like building a 2.6 liter instead of a 2.8 liter, why would you want to do that for. More cubes, more power My 350 pulls hard to 7,000 rpm.