Brad-ManQ45

A 7" wheel with 0 offset will have a 4" backspacing - there is ~.5" added to the advertised width for the bead of the tire. Z Service Unlimited in Marietta and later Smyrna GA had a 600+ dyno'd 280ZXT and rand 8" custom rims (HRE) all around with 245/50/16 tires. They had to cut and roll in the fenderwells.

Do what several others have done and go w/a 3" from downpipe back to a 3" in Magnaflow with dual outs. I myself have a 3" cat (I have inspections) and a 3" straight thru DynoMax Ultraflow oval canister muffler that is not quiet at idle but doesn't get real loud either. Sounds like a V8 at idle....

Just as on a naturally aspirated engine, making a change to the exhaust system can sometimes mean making a change to the camshaft to take advantage of the change. No-one in racing is in the habit of giving away specifics, but I could give you 3 scenarios: The exhaust was flowing a lot better, so they changed the amount of duration on the exhuast side (shortened it), or they got to change the duration on the intake side, or BOTH. The book did not mention specifics, just that that is what got them more power. They had already maxed the power with the log type of manifold and settled on the best cam for it. You have to look at everything in/on the engine working as a WHOLE, not just a collection of good parts. I can guarantee you that a Victor Jr. Intake and 780 cfm carb, 1.5" headers and a mild cam will run for crap. The same intake with 1.75" headers and a cam that makes peak power in the 6K range will be quite nice. Or change the intake and keep the small headers and cam and go with a Performer intake and 600 cfm carb and you would have a very nice running package for a daily driven sedan.

I think my 7th edition of the JTR manual says that you can raise the spring perch on the rear 2", and use 280ZX 2+2 springs with 3 1/4 coils or so cut out, and be able to run a 245/50/16 tire on an 8" wheel w/5.5" backspacing w/no modifications to the wheelwells. I believe they said that the spring rate would be around 200 lb/in. I don't think that's too far off the Tociko spring rates.... The nice thing about this would be that you could run a 26" tire You could get a nice drag slick on an 8" rim in a 14" size with a high sidewall that would be great for drags under there. Or lose a little sidewall and go with a 15" heel AND 8" rim. If you're looking at DOT leagal tires, then stick with a 15" rim and drag radials. You haven't said what your use for the car will be, which we need to know in order to help you better. If you are going to autox or roadrace, we need to know that. By the way, for autox, you really don't want a 17" or larger wheel. Smaller whee/tire combos tend to be more predictable on the ragged edge. That, and they weigh less too! (Same for drag wheel/tire combos). Remember, you get a 1.5X hit because you're talking about rotational weight here. It takes less horsepower to accelerate the smaller in diameter wheels with the same overall wheel/tire diameter (the proviso being that you arte comparing the same wheels in different sizes - same rim width). The taller wheel HAS to weigh more.

A log type manifold will limit power. Check out Hugh MacInnes TURBOCHARGING. They talked about a 2 liter BMW that was making 540 HP w/a log manifold, then went to a tuned header and picked up 60 HP. Changing the cam to take advantage of the tuned header got another 40 HP. THey then went on to using a divided turbine housing with a split collector (still tuned). They didn't pick up any power, but spool was nearly instantaneous. What I got from the example: Tuned (equal length) headers will produce the most power. For drag racing, you don't need to go with a divided turbine housing and associated split collector design, but for autox and road racing, it would be a GOOD thing.

Stock block and rear gear, T3/T4OE 50 trim compressor and .63 Stage3 or 5 exhaust, intercooled. What would be a good stall speed if running ~18 lbs boost? I figure it'll be all there by ~3000 to 3200 rpm, but how do you pick a converter for a turbo?

It took me a year, but I convinced my brother-in-law to lose the 22" wheels that came on his Navigator via the previous owner. I think the $280 a tire had more to do with it, but I kept telling him that he'd get better city mileage and much better ride, brake better and lose a bit of quick steering response and only have to pay 1/2 for good Michelins (the only tire made in the size he needed was Nitto). I found 4 take-offs with 18K on the Michelins for $485 shipped and he just put them on yesterday and took a trip today out of town. He was very pleased. He sold the stuff he took off for $3000, which put him in a good mood too.

Based on data amassed in the test, 205's are probably about as small as you want to go, and 7" is usually the spec'd rim width for them. Remember, the lower the aspect ratio of the tire, the narrower the rim width range that will work with it. On the other hand, there isn't as great a degree of difference between using the narrowest or widest width. I would think that the 205/45/17 would be ideal for you - you keep a good width on the front controlled well by the rim and you get some rake because they are shorter , then tune the suspension some. I really don't know what you have for power and your intended goals, so it's kinda hard to say. I am assuming daily driver/weekend warrior. Just like the 'vettes have done, a large difference in width front and rear helps in rainy weather the front tires start clearing the path for the rears and don't hydroplane as much as wider tires, they also are lighter for acceleration than wider tires. If you were going to tell me you were going to autox, then I'd say go with 16" wheels and have a bit taller sidewall - much more predictable at the edge. They also weigh less, so acceleration would be better. Personally, 16" is as big as I will go on the street or track (and I KNOW I'm missing out on some good tires) and when at a drag strip, will run 14's all around - drag fronts and slicks in back. I don't like the looks of rubber bands for tires, and they sure don't do anything for acceleration or traction (drag racing) with those short sidewalls. I look at the trend to bigger wheels like the automakers creation of the SUV market - style and image over function and ride. Too many people are willing to override common sense because the masses have been brainwashed by marketing. Sorry for the rant, but SUV's and big wheels and tires are a big gripe for me - I had a resaurant in the 'hood here in Atlanta and saw people with little money buying SUV's and putting on (expensive/stupid) big wheels and tires and not be able to afford gas for them, or to feed their kids.

You can go to www.tirerack.com, do a search for a tire size, choose a manufacturer/type of tire and then once you select a certain tire you may be interested in, look at the specs page. The specs page has all kinds of info like overall diameter, tread width, load ratings, measured rim width and suggested rim widths.

I will agree that tuned headers are not important for peak power, however, they DO effect spool response, and you won't have to take my work for it, I will quote a few lines from "Turbocharging" by Hugh MacInnes: Withoust arguing semantics with anyone, it is apparent that equal length IS important to maximize throttle response, and certainly will increase horsepower. Whether used with a divided turbo or not. Will this manifold produce more power than stock? Undoubtedly. Will this manifold lower spool response? Hard to answer, though if cross section area of runners is same as port then I doubt it. Would it be better if all runners were the same length? Undoubtedly. Would it be better if it had a split collector to take advantage of a split turbine housing? Undoubtedly. Would it be better if it had some SS accordion fitting betwwn the center part and the outboard runners ala tje euro ZXT manifold? I believe so, but jet hot coating will probably minimize the expansion that can break the tubes. Would it be better if it had provision for a wastegate? Depends on what you want to do. There is now a much improved internal WG housing for the GTR turbos that eliminate the need for an external WG with them and will fit most 5-bolt (Ford) T3 turbine housings. I laud the manufacturer for his efforts, it does look like a nice manifold. If the runner area is no larger than the port area and the quality of construction is good, then I believe it is a reasonable price. I however, agree with jgkurz, when I am going to start shelling out this kind of money, I want all the bells and whistles, and am willing to pay for it. Either that or have to make it myself. I have too much other stuff to do, so I'd rather pay for it. If someone would step up to the plate with a product with all the bells and whistles, there WILL be a market. Perhaps this manufacturer may look at what we are saying as a very good/astute/cheap marketing survey and determine that he can provide a product that the more cogniscenti want. I certainly would look forward to it.

The air may be a little low, but you have a smaller tire holding up marginally more weight, so the bottom would flatten more. I took care to look at the sidewalls in the front and rear of the tire itself to avoid the possibility of this factor skewing my observation. That said, I think that if you think the fronts look too tall now, that 225's won't do it for you, because they are only .1" less in overall diameter. The 215's would be .4" shorter, and would also be a better match for the wheel for handling purposes. 7" is the minimum and usually spec'd rim width for this size/aspect ratio. I'm not sure everyone is aware of this, I may have mentioned it in the past, but will reiterate if I have: In the early 90's, Turbo Magazine was building a Mistubishi Eclipse. They had upgraded the suspension to the max and were looking at tires for the wheels they could fit. I remember vividly my surprise when on the wheels they had that the tires that the wheel was the widest spec for out-cornered the next wider size tire on the same wheel. They even did pyrometer testing across the tread width to verify the amount of traction and how much of the tread was being used, varying the air pressures for each corner as they tested. They were using 205/55/16's and 225/50/16's in the test. The smaller width tire had a more even temperature across the tread than the wider tire, which indicated that there was a lot of "squirming" going on which did not let all the rubber stay in contact with the tarmac. To get the best handling out of a tire, go with the widest rim that falls within the manufacturers' specs for the tire. You can reverse that a bit and say that given a certain size rim, what is my best choice in tire width. In a nutshell, if you are after the best traction (and you DO want to minimize push, as you stated), then the 215's would be closer to the ideal than 225's on your 7" rims. It would appear though, if one were to learn from the above real case scenario, that a 205/45/17 would provide a more stable tread and be a total of .7" shorter in overall diameter than the tires you have on the front now, giving you that bit of rake that you are also looking for. The shorter sidewalls should help controll the tread more. A few more things that you can look at, not knowing what you have done for bushings and anti-sway bars, is a little tuning in this area. Some people, in order to achieve the correct "feel" will tune the suspension by utilizing urethane bushings on the end of the car that needs to be stiffer and regular rubber bushings at the other end in order to get that last degree of "feel". If the amount of push you are experiencing is more than a bushing swap can take care of, then possibly a slightly larger rear bar... Don't forget that tire pressures are a tuning tool also.

I don't know about the "tuned" part of his statement above. Every article I've read about tuned headers has referred to equal length runners so that the exhaust pulses arrive in timed sequence no matter what rpm you're at. His runners are not all the same length. I have no doubt that they are freer-flowing than the stock manifold though. I would be interested to know what the inside diameter is of the tubing he uses. You definitely don't want it larger than the port area, that would only slow down the exhaust gases and allow for expansion/cooling before hitting the turbo.

Phantom: With the exception of Car Provider, I'm there. Computers, Audio/Video, house wiring, plumbing, sheetrock, building decks, auto repair or finding a good deal on something, I'm the family&friends (even friends of friends) go-to guy. The one area I don't touch (except for my own stuff) is woodworking, my father being the one that people go to. I let him have his area and I'm glad he's there for it, but I do my own because I'm anal , take my time and think it out better (the programmer in me). Between helping everyone and the honey-do's, business and lawn work, I have very little time for my own stuff. Right now everyone is reveling in the fact that I built a blast cabinet (2'x2'x4'). This project drug on and on for the reasons mentioned. The best part of this is that I get to sit on my butt drinking their booze while cleaning up their messes! (I really enjoy making things look good) I wouldn't have it any other way....

Moby: Have you checked out the peak & hold boards that were in the expansion board forum? I got 4 of them (2 projects), hoping to avoid some of those issues even w/MSI_Extra. I will HAVE to have MSII because I need to use a GPIO board for controlling a 4L60E, all I'm waiting on is wasted spark from the Extra code.

If you have a +12mm offset on a 8" wheel, the dish would be LESS than the dish on the rears with a +22mm offset - the rears are .5" wider on each side and the offset difference is only 10mm, which is obviously less than 1/2".

I saved the pic you have and viewed and enlarged and have a question: Are you sure you don't have 255/40/17's on the back? That would make the 205/50/17's sidewalls .05" taller each - total diameter +.1" . That is what it looks like to me - but may be an optical illusion.... 255/50/17's sidewalls would be 1" taller each than the 205/50/17 - total diameter +2", and I'm just not seeing it, once again, this could be an optical illusion. It DOES look to me that you have ~ the same sidewall height front and rear, which is why I am asking. If you DO in fact have 255/40/17 rears, then a 225/45/17 would be exactly the same height, and a 215/45/17 would provide a little rake.

All day, I get the same error in FireFox and Explorer..... Just wondering.

I'm saving the last 1/3 bottle of JW Blue for after I get mine out, one drink, then the rest for when the car is finished - okay - actually fully functioning and painted. (75 ground up, subchassis connectors, floorpans, rear quarter and front fenders. I just bought the last Arizona Z Car Gnose, and will be reinforcing it after I have it bolted up. It's a bottle that was sent to me by a customer that I did some custom programming for in addition to my fee. I made the mistake of inviting my father and brother-in-law over and had to rescue the remainder! I'd only had one...honest! (I keep it hidden now)

Good deal man, congrats!

You can look at how long I've been around - I've got an '83ZXT, and I've never run across this manifold, and believe me, I've searched. That said, 14 guage is nice. If you get one, get it coated! I'm probably gonna build one of my own - I have a MIG that I need to use for more than body/subchassis connector work now that the rotisserie is done....

Boy, I feel great - Clifton and I are sympatico on what you should do! Clifton - I'm gonna MS my '83ZXT, and will be going w/MSII like you! znow: Clifton knows a lot and verifies all the research I've been doing the past 1.5 years, so I feel very confident in my choice. I will say that I intend to have it built for me, but I want to build the stim just so I can check it if I do something bone-headed when I'm wiring it or in cased I ever run into a problem in the future - the soldering practice and reading the schematics will be a much needed refresher for me as the last kits I built were as a scout over 30 years ago. If I can handle the stim, I'll probably want to build the next MS unit for my '75 v8 project.

If you do have a friend that can help, I see no reason NOT to do the MS swap. The only reason to go with MS I at this point is if you HAVE to go wasted spark/COP for ignition, which is more $. MS II will work with the stock ignition and in a short time will be able to support WS. We are talking a bare bones comparison here. MS will let you tune to your hearts desire and change things around (like boost and injectors) and timing, which the MAS 300ZX system will NOT let you do unless you pay someone to do it and have to wait and wait to get it done. If you go PAST bare bones, MS has a heck of a lot more potential. Read the "1 hr MS install" thread. Easy decision for me.....

I have them and Illuminas on my '83 ZXT and love 'em.

Good news! I too will enjoy seeing you run again at SEZ7. Watching you and Dr_Hunt was a real treat that I could reapeat as often as possible.

Try doing a search....