johnc

Funny how that works out... Jim Thompson and I talked a long time before we started on my engine build. He wanted to build a cam for the L6 from scratch because, based on his research, all the aftermarket cams he had worked with previously were based on BMW profiles - at least as far as he could determine (at the time he was building the race engines under contract for BMW and Mazda for their World Challenge Touring efforts). A lot of his research effort went into properly modeling the L6 valve train and from that he was able to work with Piper to develop a profile that required less (then OEM) closed spring seat pressure (load) and still be stable to 8,000 rpm. This was after he welded and cut on two different N42 heads and ran them on the flow bench. He actually picked the head that had the lower peak flow numbers but was almost dead on equal for the exhaust ports and dead on equal for the intake ports. This was a two year effort and the engine spent about 20 hours on the engine dyno. from that he made welding and porting templates for the head and had a few cams made. I think all of that is NLA now that Sunbelt is now Kinetic.

Great pics! Thanks for posting. Amazing amount of work done on the front of the car.

The recommended wheel widths listed in all tire advertising in the US is per a DOT rule. The widths are a recommended safe range within normal operation on a street driven car. Per Jeff Speer at Hoosier and Rudy at Kumho, the ideal performance rim width is .5" wider then the actual measured tread width (between the tips of the wear indicating triangles). And the actual tread width has little do do with advertised tread or section width. I used to run Hoosier R6 race tires listed at 275. The actual tread width was 297.

As mentioned above, it will scratcha nd haze easily. The scratch resistant coating helps extend the scratch free life of the lexan by about 50%. So, you'll go from one year to 18 months before it looks like crap, but you'll pay 100% more for the scratch resistance. You do the math.

Cut out the core support as one piece. Don't cut it in half, you'll never get it straight again. If you need to cut the wheel well and the upper frame horns in addition to the lower frame rail, cut it back close to the strut tower. Might as well use the strut tower flange as a guide to cut a straight line.

I made it a point to say that my engine was not a production engine. But even for production engines I think your rule of thumb is way low. For my particular racing 3L I had the builder optimize the engine for torque with as broad a torque curve as possible. Lots of head work including welding up and re-contouring the exhaust and intake ports so they all flowed the same. Development work on three different custom cam profiles, individual ignition timing for each cylinder through the Motec EMS, custom intake manifold, custom header, etc. It made 285 to 294 whp (depending on the chassis dyno used) and a consistent 325 horsepower on the engine dyno. There was a lot of tuning of intake runner length a taper, header primary size and collector merge, and a lot EMS programming to get the numbers my engine developed. The engine builder said it would have been a lot easier to build a horsepower engine. All the components were there to run the engine to 8,500 rpm but my imposed torque goal made that unnecessary. You should also search for a couple of Tony's posts regarding the L6 harmonics in the 7,000 to 8,000 rpm range. L6 engines are happy below and generally happy above that range. Within that range the harmonics require forged pistons, good rods, and outstanding balancing. For my engine the builder took 15 lbs. out of the crank, 25 lbs. out of the clutch and flywheel, and added a ATI Super Damper.

R160s use a 25 spine side shaft. The stock Datsun R180 side shafts will work but you need to determine, as mentioned above, if the diff requires a bolt-in or snap ring style 25 spline side shaft. You Z31 CVs will not fit, they are 29 spline.

No. Way low. My 3L L6 engine made a max of 275 ft. lbs. of torque and had at least 200 ft. lbs. from 4,000 to 7,200 rpms. 13.6 to 1 CR, Motec M48, V07 crank, JE pistons, 65mm TB, 4.5L plenum, 7.5" tapered intake runners, custom cam, lots of head work, etc. It was not a production engine and ran on Sunoco GT Supreme race fuel.

Its purely and alignment/suspension problem.

Oops. My mistake on the turbo engine CR.

That's a very low number. Most likely rings. When you had the head off did you check to see if the rings had stuck or rusted to the cylinder walls due to the engine sitting for a long time?

Powerband was typical high horsepower L6. Nothing below 4,000 rpm and then a whole bunch until 7,500 when it started to fall off. BTW... in all racing classes where the NA engine is essentially unrestricted except for an inlet restrictor, the builders make as large a plenum as possible. I once saw a VG30DE engine make 423hp on an engine dyno through one 35mm restrictor. That engine went on to win the LMP2 class during the ALMS race at Road Atlanta (Petit LeMans).

I guess that means I had a 19/16ths race cam in my engine.

SCCA ITS 240Zs running 14" wheels and 225/45-15 tires are about the lowest anyone has run with a good handling 240Z. 5" ride height measured at the rockers. Lower just puts everything in a bad part of the camber curve and exacerbates steering kickback and bump steer. That's assuming you're not doing anything to relocate suspension mounting points. If you're relocating the inner mounting points of the front and rear lower control arms I can see being able to run about 1" lower using the same size wheels and tires.

The "short stroke" shocks in question are Tokico HTS 102Fs and their stroke is 1" shorter then the generally accepted 6" stroke for a S30 application. That shock can be run if your overall tire diameter is under 24". With a larger OD tire you need to raise the ride height to get good handling. The car in your picture above is too low for an S30 with the size of wheels and tires pictured. It will be on the bump stops all the time and will be pretty skatey in a corner.

100hp per L is a mild race engine build. 2.4L L6 engines built to ITS rules (stock cam, crank, pistons, SUs, no porting, etc.) make 208hp at the crank. FP 2.4L builds make more then your magic whp number with 12 to 1 CR, .500 lift cam, SUs, header, etc. and spin past 7,500 rpm.

Well, on a no limit NA build I had a custom manifold that was exactly 1.5 times the total displacement of the engine. Engine builder went to a lot of work to make sure that was the volume, even calculating for the loss in volume from the 6 TWM velocity stacks inside the plenum that fed the runners. EDIT: He also included 1/6 of the total runner volume in his calcs.

If you want the rpm then stick with a 2.4L L6. It does a little bit better then the 2.8L at high rpm. You can make 200hp easily with an NA L24 given freedom in head, cam, and piston choice. And the RSX weighs at least 350 lbs more then your 260Z unless its full of junk.

You can use a rivet nut but you'll have to change the bolt thread pitch to 1.5p for that one fastener. http://www.mcmaster.com/#threaded-inserts/=dzkmip

You brake pressure differential switch has been tripped. You need to reset it per the FSM and then your rear brakes should bleed fine.

Nissan made a number of changes throughout the years to the brake line routing on the S30s. Get a model/year specific brake line kit.

I think the OP is confused by the terminology. What he wants to do is seam welding and: 1. It does help the S30 chassis 2. Its a lot of work 3. You can seam weld without having the car sandblasted but you would be a masochist to do that 4. You have to paint/seal the welded areas

Timesert. You need the M10 x 1.25p kit. http://www.timesert.com/html/mtrcsert.html

The closest I have to any empirical data is some FEI analysis done by Bill Savage at T-Mag back when he did some work for me on the rusty old Datsun. The biggest weak areas on the model he and I made of the S30 was the connection of the firewall to the rockers and the floors. That area acted like and hinge. Within the limited rule set I was building to we built a triangulated strut tower brace and I (illegally) added some reinforcement to the upper frame horns and filled in the open box (my car was a 1970) on each side of the firewall connecting the rocker, fire wall, and cowl. Those changes, along with a welded in roll bar, let me run spring rates 350% higher then OEM. It stopped the chassis cracking that had regularly been occurring at the firewall/floorpan junction when I was running 225/50-15 Hoosiers - even after upgrading to 275/45-16 Hoosiers. If I had a full roll cage with braces to the top of the firewall and through the firewall to the strut towers the little analysis we did says we could have gone 600% higher on spring rates. None of the analysis we did showed any strength issues with the rockers. Now, its was a pretty rudimentary analysis done 11 years ago and FEI has been superseded by much more sophisticated tools and techniques. Maybe we screwed up the input parameters and got garbage results. There are a whole host of things that could (and maybe did) have gone wrong with that analysis. Unfortunately that's the best I got and on track results sorta confirmed what the software said. One way to help figure this out is to cut up a 280Z. I've cut a few and the reinforcements are mostly in the roof (for rollover protection), front frame rail/firewall/cowl junction, rear bulkhead/floor pan junction, seat mounting, suspension mounting points, front crossm ember, front frame rails. I honestly don't remember if the rockers were reinforced so hopefully someone who has cut a 280Z up and remembers can chime in here.

"Unverified claims" That's the problem. Verification. Are you volunteering to perform that function for all of the For Sale ads?