Scottie-GNZ

Not a Z but should give you some ideas. I will be doing exactly this to my RX7.

I dont necessarily have a specific answer for you, but here is something to contemplate and maybe seek some further input from experts. While there is a big difference in dispalcement between a 5.7L V-8 and a 3.8L V-6, there is no difference in the volume of air the engine will displace if the V-6 is pushing say 24# boost making 480hp and the V-8 is pushing 13# making the same. The primaries on the V-6 would appear to be extremely small but when aftermarket headers with larger primaries and x-over pipe are added, the performance suffers because of the velocity change. The V-6s making mega HP of course benefits. So, if you are looking to be in that HP range or a little higher, make sure you size the primaries right and get advice from a turbo expert not an N/A Chevy guy. Remember, with a turbo car, it is not necessarily engine displacement that counts but how much air the engine is displacing. Another key factor when building a street turbo with good crisp reponse.

Good advice so far. Here is what I would do for starters: - Check the connector to the O2 to make sure it is not disconnected. - Replace the O2. I believe that engine uses the same 1-wire O2 as the '87 and I pay ~$26 new at Autozone with a lifetime warranty! - You can also check the coilpack with a meter. Set the meter to 20K Ohms and check the resistance between the terminals of a coil and it should be between 11-13. Not uncommon to see one completely dead. - Before you restart the engine you must reset the ECM. It sounds like whatever the problem has caused the ECM to go into limp home mode. This will also clear the 44 code. Simplest way is to disconnect the battery and wait 10 seconds. If the problem persists, DO NOT run the engine if it idles bad and black smoke is pouring out the tailpipes. That is limp home mode and you will eventually wash down the cylinder walls. MOF, that will have an impact on the compression reading. If you did this a lot, I would suggest fresh oil and a filter as cheap insurance.

The car is an n/a automatic. Drop me an email letting me know what you might need. If there are any S30 mad scientists out there, you can have the entire front suspension cheap to experiment with. Would prefer a local pickup since they would probably require a pallet.

I seem to recall some time back that scca (anyone heard from him?) had put Z32 brakes (fronts I think) on his 260Z. Anyone else ever done this or considered it? I just picked up a '90 Z32 that I will be parting out and thought that would be a great swap. Bigger brakes, alum calipers and 5-lug.

You are only looking for 300RWHP, so unless the engine is in bad shape, why bother rebuilding it? Freshen up the head with a 3-angle valve job, do some mild port matching, ditch the Supra I/C and invest in a good I/C and DP and tune, tune, tune. You do not need anything more to reach your goal if you have an SDS, injs, upgraded turbo, good I/C and exhaust.

Here is another way to look at it. How many gallons could you have possibly bought? 12? 13? 12 gallons would have cost you an extra $1.32!! I know its pshycological but if $1.32 is worth the risk of detonation and an engine repair bill, then it's time to start driving a Honda . Kind of makes me chuckle when I hear things like this or the person driving the gas guzzler who will drive some extra distance using another 1/2-gal looking to find gas $.02/gal cheaper

If another turbo with an internal gate is an option, then look into some of the turbos used by the Buick turbo folks. It would require you to mod the turbo mounting on the header with a 3-bolt-unit but that should not be too difficult unless the manifold is made from some kind of "pig" iron that is difficult to weld. No problem finding one on the Buick boards that can support 500-600hp for a reasonable price. Of course, the trick with the internal gate is finding a wastegate cannister with a spring soft enough to keep the boost at 5psi. The GN stock spring is 12psi so that is out. Most that have a spring that soft are for small turbos so you have to mod the cannister bracket to fit a bigger turbo. I have extra brackets if you decide to go that route. If the reason for running such low boost is to avoid detonation, then consider an alcohol injection unit. Again, fairly common in the Buick world and when you consider what you might have to spend for making the external wastegate setup or replacing the turbo, it might be a good option.

This might be what you are looking for. Ignore the dump pipe if you are not using one.

20psi on pump gas blows a head gasket and there is surprise? Repeat after me: "OCTANE", "OCTANE", "OCTANE", "OCTANE", "OCTANE", "OCTANE", "OCTANE", "OCTANE"............

Similar to Pyro. 134.93 in the 1/4-mile @ 5400 RPMs. Buick 3.8L turbo, TH200-4r trans in 3rd with convertor locked, 3.07 final drive, 26.4" tire. Still pulling? Yup, as it only took 3.67 to reach that speed from 100mph. Projected top speed? More than I have the B*LLs to find out or what would be considered safe in Z w/o lots of aero tricks. I have given it some thought and in a what-if scenario, 5700 redline in 3rd would put it at 142.4 in a couple of seconds. Shift to OD (.67) would drop the RPMs to 3820 and given some road it would creep back into the torque curve and maybe see 5000 again. 5000 is 186 Totally meaningless but makes for good water-cooler talk :D

Clifton, you are killing with this generic "bigger turbo means more lag" statement :D I absolutely agree with you and what Alex said. "Most people struggle to make 300-350rwhp because they are using turbos that are too small and will only flow enough air for 300-350 rwhp"....and they are not running enough boost to make the HP, and the insistence on running pump gas, and the engine is not optimally tuned. I know people will look at my setup and dismiss it as not being a good comparison, but it actually is. I am running 26psi boost with a 66mm turbo and my bottom-end is stock except for ARP rod bolts (as per Alex) AND I am running hyperuetectic (sp?) pistons which some would say is a down-grade. My bottom-end was assembled in Dec '99! I run a C-16 mix at the track with no detonation and I could push harder, I just choose not to. Now on the street, I can barely go over 16psi with pump gas. Sure I could get it higher if I tuned it for higher boost on the street but I choose not to. I would say the difference between my pump gas/16psi setup and my race gas/26psi/more timing setup is about 150hp. The beauty of a turbo engine is that you can make it a Jekyll/Hyde and do it safely, unless you just must have full boost on pump gas. I continue to be puzzled why folks spend thou$and$ to build a turbo car then strangle it at the track with pump gas and risk serious detonation on the street.

Scottie never ran the GNZ on a road racing track... Some of the changes necessary to fit it under the Z might have compromised its performance (roll centers especially). Absolutely agree with everything said. Keep in mind though that I knew my Z would never go pass the parking lot of a road race track BUT for a street car running in the twisty hills of Central FL, it could hold its own :D Like John said, there is no best when you are trying to build a multi-purpose car. You have to be honest with yourself and answer the question of whether or not the car will see both a drag strip AND a road course. I think most people are kidding themselves if they say both and chances are the car will see drag strip duty and street cruising. All the R230 and custom axles in the world will not fix the fact that the weak point is still the stubs when launching a 500hp manual tranny monster hard with slicks or ET Streets/QTPs. You are going to break stubs! I am a big advocate of using a stout IRS in this situation but I was running an automatic and DRs with a softer launch mighht hold up for you. OTOH, I snapped a 280ZXT CV with DRs. I would never sway anyone away from the R200 upgrade or R230 swap, but, make sure you understand the complete cost of all the swaps and you might be surprised, especially if cost is a factor. Combine the cost with how you honestly plan to use the car and make your own decision. BTW, when you hit 500hp, you will want more!

I was in the same boat you are in. My little 3.8L makes the power/torque you are referring to, i.e, 500+hp/600+ lb/ft torque and is not a high revver. As for the RPM issue, so what if it only revs to 4400. Take advantage of the power curve, gear accordingly and ignore those who think you have to have RPMs to make power. One thing you might consider to help the RPM issue is a little stiffer valve spring, but not so stiff as to wipe out the cam. This is a known problem in the Buick turbo world and not unusual to see an engine die at 5000 and pick up 100hp with just a fresh set of valve springs. Remember, Caddy was not thinking performance so those springs were probably dead after 10K miles. Tough call on the tranny but w/o OD and LU and a 3.54 gear, you will get poor mileage on the highway and possibly put too much heat in tranny because of converter slip which will probably be 200-300 more RPMs @ 65mph over LU. Thus the tall gearing in that car. The R200 3.36 came in the 79 280ZX 2+2 with a 4-spd. Others have claimed it came in other models but that is unconfirmed. With the automatic your problem will be the axles not the R200 so going to a R230 buys you nothing except it guarantees a LSD. The highest ratio for the R230 is 3.54 anyway. The dilemna I faced was finding a ratio that would allow me to trap at 135+ in 3rd. The NISMO gear, 3.06 if I recall, would have been perfect but at $600 + $400 for a used R200 LSD + $125 for the gear swap and new clutches + $800 for a pair of custom axles to withstand the abuse I would put on them + $800 for a spare pair being they are not even length and the C4 swap just made sense. I know you do not want to do that but I was just trying to make a point that the expense of the tranny option is not to be ignored.

Ah, the old gear ratio post again. Here is how I approach it. Thumper is correct when he says it depends on your setup and power band. You need to look at overall ratio, not just final drive ratio. Never forget that tire diameter has a big effect on overall ratio. You run a 3.70 with 24.5" tires then jump up to 26" 235/60-15 DR and your effective overall ratio is no longer the same. You need to figure out where in your power band you want to go through the traps at. In the stocker, 5700 is about right. You need to do the math to see what effective final drive will get you through the traps at that RPM at the MPH the car is capable of. In the case of a 240Z with a stock L28ET running a fair amount of boost, that should be about 110+. With a 24.8" tire you would go thru the traps at about 5700, just right. If you throw on a bigger turbo and more mods but leave the internals alone, you will be pushing enough power, when tuned to approach even 124+. Lots more power and torque but you will still be going thru the traps at 5700. Remember, this is not a N/A where you need a cam and have to rev the piss out of the engine to make power. WIth the same gearing and tire, you will now be trapping at close to 6400. Drop the ratio to 3.54 and you will be trapping at a little over 6100 and 3.36 will have you trapping at about 5800. 3.54 and a 26" tire will have you trapping at about 5850, so you see what I mean about the effect of the tire diameter. Is the taller gear not going to hurt the acceleration? NO! This is not a N/A, remember. That extra 100hp you added to trap 124mph probably also added more than 100 lb/ft of torque AND give you higher torque down low than you had before. Now let's say you decide to add a little spray or some real race gas and run the boost most here seem to be afraid of, the car is capable of trapping in the high 120s or more but you still need to trap at 5700. On the other hand if you go with a cam and bigger valves and hogged out ports, custom intake, etc, you will now probably need to trap at 6500+ so the gear ratio will be different. The more time the engine spends in 2nd and 3rd building boost in the meat of the torque curve, the quicker the car will be. Just take a look at what 240Z Turbo just did. He runs a 3.70 and went from a 3-spd JATCO with probably a 3.xx 1st gear to a 2-sp P-Glide with a 1.76 1st gear!!!! and now his car is flying with lots more potential to go quicker. That tall gearing should have slowed him down

Thanks all. I spoke with Wilwood yesterday trying to understand the applicability of the residual valve and they said it is not needed here. However, I must bleed the highest point and that will not be so easy since there is no bleeder screw at that point. This confirms what another local expert told me. Find out today.

From the factory, it is 3:36 and it is very rare and treasured. NISMO does have a taller set but bring a jar of vasoline when you go to pay for it. before you consider spending that kind of $$$, look into a tranny with OD and converter lockup as another option.

That DP was designed specifically for the stock T3 and T3/T04 hybrids. With the T3 wastegate having a 2 1/8" id outlet I never gave much thought to exceeding the HP limit you are at now. You have to wonder if a larger diameter pipe would help but you also have to look at how much HP is being extracted from a 3" pipe and wonder if the 2.5" limit has been reached. The most HP I personally know of is a buddy here who ran a 240Z with a j/y L28ET, hybrid turbo, SDS, Spearco and with 22psi on street tires the car went 11.7 @ 119. That factors out to 337RWHP but since that is derived from a 1/4-mile and not peak like on a dyno, we were estimating it would closer to 350+ on a dyno. Based on how the car ran we never gave any thought to the DP being a restriction. I am at 520RWHP based on my 1/4-mile (how much on a dyno???) and plan sometime in the future to up that about 10% and going bigger than the 3" I now run is not even a consideration. If you are just looking for a couple more HP, I say instead of spending $$$ for a 3" mandrel SS DP, do some more tuning to get the A/F from 10.0:1 to around 11.2. You might be amazed what that will gain and of course cost you nothing. I say take it out and spend a couple of $$$ to polish it to a miror finish :D j/k. OTOH, go for it if just must have it. Nothing worse than having a nagging feeling that something isnot right.

Jim, simply awesome! Curious though after what the swap entailed that you did not go all the way and also do the Viper IRS. The Viper diff and batwing is identical to the C4 DANA44 and I cannot imagine the swap would have been any more difficult than my C4 IRS swap. With what it will cost to do a R200/Quaife, beefed-up CVs, CV adaptors, 5-lug conversion, tada yada..... and you will always still be on the brink of snapping those CVs with that monster.

Please don't get caught up in the hyped-up, over-inflated HP numbers from cars in that era. Those were gross HP numbers mostly derived from the dyno with no accessories or from the heads of marketeers, some of whom did not even have the sense to not round up the numbers. 16.25 @ 83 in 5700lb car (gas and driver) equates to ~255 RWHP or ~ 305 at the flywheel. If someone wants to put one of these in a Z to be unique, that's fine, but to think with some mods you have a 600hp hybridZ is far from real. IMHO, a Z with a well-tuned modern-day LS1 or even LT1 will outperform a Z with one of these stock monster Caddy or Tornado, et al big block lumps.

Thanks for the clarification. Sounds like in my case it would best be located in the new line I added between the RX7 p-valve and the line-loc.

Good advice but one minor correction. Engine displacement is not a factor. It is all about HP and airflow. You need air flowing into the engine to make HP and a 1500hp supercharged 8.0L BBC requires the same amount of air as the old 1.5L F1 turbo engines that made the same HP in qualifying form. That's the best I could come up with to emphasize the point

Mike, thanks for the reply. It seems like a residual valve is another term for a proportioning valve. If so I am still not sure if my concern goes away. What I probably ought to do is fully explain what I am trying to do. ****WARNING: I AM GOING TO RAMBLE A LOT OF TECHNO-BABBLE ***** I am installing a line-loc but the line-loc is being installed in the rear brake line, backwards! the RX7 m/c has separate LF and RF lines coming out of it. The LF goes directly to the caliper but the RF along with the rear, goes into a proportioning valve. There is no way I can install the line-loc in the front brakes and have it work for both sides w/o redoing the front brake lines and possibly throwing off the calibration in the p-valve. By installing the line-loc in the rear, backwwards, I get the same effect using a different burnout technique. In this case I have to engage the line-loc, then hold the brakes and the line-loc duing the burnout. This locks the front brakes but prevents any fluid from getting to the rears leaving them free to spin. Unfortunately, finding a spot for the line-loc forced me to put it above the m/c. My concern is that there is no way I can get fluid into and retained in the line-loc when I fill the m/c. So, when I engage the brakes, the fluid from the m/c will be fronted with a pocket of air in the line-loc and this will happen every time no matter how well I bleed since as soon as I come off the brakes, fluid will run (or at least try) back into the m/c. If the m/c is sealed then I will surely make a mess when I open it. Somewhat related to the problem is the fact that I am also installing a hydraulically-actuated throttle stop that extends to limit the travel of the TB while I am foot-braking at the line. The tee for plumbing in this contraption is right after the line-loc so when I engage the line-loc during burnout it does not activate the throttle-stop and limit TB travel. Because the tee connection is also above the m/c, it could affect the t-stop. Still with me? :D Below you see a pic of the installation not 100% done. You see the p-valve is below the m/c and the RF and rear lines come into it from the bottom. The outlet port next to the m/c is the RF and the other port used to go directly to the rears but now goes into the line-loc. Those familiar with the Biondo line-loc can see it is installed backwards. Coming out of the line-loc is a tee with a plug where the t-stop line will go and then the rear brake line. As Richard Pryor would say, "IS THE BOY CRAZY?" :D So, do I still have a concern?

Stop wasting all that money for passes on dynos. Invest in an LM-1. Find a buddy or 2 who has the same interest and share the cost. Then, take the car to the track and run it and tune it in the process. Eventually you will become one with the car from seat time and learn to tune your car in the process. What good is a peak HP dyno number unless you just want it to brag? A big dyno number is useless if you cannot put that power to the ground. Going quick down the 1/4-mile is more than having lots of HP. Forget about attaining a HP number. Tune it at the track to increase MPH and with seat time, experimentation with tire pressure, burnout and launch technique, quicken the 60' time. Then you can brag about a stunning ET/MPH and just think of the fun you will have doing it. I do not have the biggest HP number here but I have one of the quickest street-driven cars because I focus on more than HP. Tuning, seat time, tuning, suspension, tuning and , oh yeah, tuning. In case you do not get my drift, you tune more than just the engine. The GNZ has been to the dyno once and it was a waste of my time and money.

Stop trying to make sense of dyno numbers and how those numbers compare. The only comparison you should be concerned about is those between your passes on the same dyno, regardless of how the dyno derives its number.