260Z Dyno Plot

[Ron Earp]

Well, what the heck. Here is a dyno plot from the 260Z that I race (try to race I should say, maybe next week I won't catch fire). Inline 6, 2.6L, stock carbs, cam, etc. just attention to detail with port work, cam timing, exhaust with headers, and some other tweaks. IT is very restrictive so we can't do much.

Not a lot of power, only about 225 (ignore the bump there) and I don't think it is a real "225", that is just this dyno. I'd estimate only 160 at the wheels or so, but it is still mighty fun in a 2600lb car on a track!

 

Ron, You mention stock everything, What was the HP rating of this motor from Factory. My cousin has the exact same car with FI and it is a dwag.. Did you do anything else besides the porting?!

By the way here is a photo of his 260Z (It is a VR rebody out of Arizona)

 

[Ron Earp]

Nice!!!! Ours doesn't look anything like that, but it is a race car and not for he street. I like those headlights.

We don't think the motor is making that sort of hp in the graph, that is the engine dyno shop that is off I think. The motor has compression bumped 0.5, good port work, great header and open exhaust, along with a lot of pulls with the cam timing at various points. I think the motor is probably putting down a solid 175-180 at the flywheel - no more. Oh, and a lot of custom work to these POS flat top carbs that everyone hates - but they run well. They were rated at 135 from the factory but that was in smog trim from 1974.

It pulls strong and has a nice flat torque curve by feel. It'll hit 132 easy at 6100 RPM and will continue to pull to about 7100 which we have to do at the longer tracks like VIR (next weekend). Definitely not the strongest ITS car in the class but no slouch either.

Ron

 

[Mark Worthington]

One of the most fun cars I've ever owned was a 240Z. That car was just a blast to drive even in stock form.

 

[John]

Hey Ron,

I'm in the planning stage of building a 240 or 260 to be an all-out corner carver. Great little cars.

I'm planning on the V8 swap myself, and shooting for a curb weight of under 2500 pounds. Should be a good time!

 

[Ron Earp]

You'll get under 2500 I think. We just got back from VIR and racing the 260Z over 5 hours there this weekend and in tech it weighed 2645, a sparse race car with the original HEAVY motor!

Race was a lot of fun, I got two completed a 45 minute and a 30 minute, and so I am now done with my novice permit. Man, what a blast! I had only done track day stuff before, but nothing compares against racing on the grid with a start of 75 cars! Timed stuff is fine, but I don't think it compares with the H2H. I've got some track photos and footage I'll put up here as soon as I unwind.

R

 

[Ian K]

Ron, you're 175 - 180 HP guess with all the work you've
done sounds about right. IIRC, my '72 240 was rated 160HP
stock form the factory.

John, under 2500 should be a cinch. The listed curb weight
for my 240 was 2400 lbs, 260's gained a little weight, 280's
a little more, and the ZX's nailed 3000 with the power seats
and power windows. The v8 swap is a dandy, I was thinking
of doing it myself until I got rid of the car (I had a
happily purring 280 block in it, and was also thinking of
punching it to 3 litres). A lot of people do the Chevy 350,
but I think the FoMoCo 289/302 is a better fit. The v8s are
shorter in length than the inline 6, and the FoMoCo dizzy
is up front, so you can get the engine ral close to the
firewall and get 50/50 weight distribution. Also, there
are some good kits out there to replace the rear drums with
discs - highly adviseable.

However, the v8 swap is not simple. A well built 280 block,
bored out to 3 litres, with the right head and exhaust, the
beefier 280 rear diff, and the 280 5 spd, along with some
carb work (the triple set up is pretty cool), and you be amazed
at how well the Zs can perform.

Ian

 

[Ross Nicol]

Hey Ron guess what I raced before the 40? Yep a 240z with L28 block,twin SU carbs,good head and cam to suit.Made 220hp
on dyno.Felt very quick and was a great car, however to put things in perspective.My fastest lap time around Phillip Island was 1min 57secs and currently in the 40 I'm lapping in 1min 48secs, thats nearly 10 secs a lap faster than the Z.
Ross

 

[Ron Earp]

No kidding! Nice power from yours too! I'll need some tips on setting this thing up, especially the front end.

Z's are fun, I just got back from over 5 hours of seat time in it this weekend and it was a ball. I had to wear the rookie stripes this weekend but got them off after the last race. I did better than I expected with upper mid pack finishes. All in all I didn't feel too bad about my first race weekend with a "new" car.

I had a lot of trouble driving the Z but that was because we had no camber in the front, or very little. Front kept washing out and just eating up the tires. In a 45 minute sprint race the tires just turned to glass since you don't try to manage them in that short of a race - you just have to push it and go for it. We'll get new plates made up and move some stuff around to get more camber. What did you usually run on your Z for camber? And, did you use a rear sway bar? I did not use one this weekend because the rear felt so good on this fast track and the car RAN - I didn't want to fix it til it broke. This car is very stable through the high speed esses etc. but low speed sharp corners it needs camber I think. Seems to be set up for high speed stability. I'd trade some of that so that I don't get killed in the slow stuff by every other car on the track.

One thing I am pleased about is that I got the damn flat tops working from 4500-7200 and that is all I care about. It will load up at idle and low RPM but man, on the straight at 6800 with the side exit straight pipe we had built it sounds awesome!

This is me getting ready to get stomped by thta spec Racer Ford taking me on the outside and my friend and business partner with his TR8 on the inside! Rookie drivers have bad lines!

 

[Ron Earp]

And free and clear of traffic - smooth sailing!

 

[Ross Nicol]

No I never ran a rear bar.To get more camber I made the lower control arms adjustable by fitting a rose joint to the inner end.Caster rods were rose jointed too.Made a difference to the turn in.I think I ended up with 3-4 degrees neg camber and tyre wear was even across tread.I ran bridgstone Potenza tyres.Do the rules allow you to lower the car?
Ross

 

[Ron Earp]

I can go a little lower but no on the heim joints on the ends. However, I do have adjustable camber plates and just need to enlarge the slots to get more camber, which we will do. We run Hoosier and Toyo race tires on the car and they do pretty good. We can lower it some more, maybe about 1" but we have to maintain about a 4" height per rules. Much lower and we'd have a hard time getting it on the trailer.

Our series is Improved Touring and there isn't that much we can do to the motors, although suspension is pretty open using stock components or simple things, which is enough.

 

[John]

The only reason I'm thinking I might tip the scales a little over 2500 is that I plan on building a full space frame chassis for the car. I've been designing the space frame using a program called GRAPE.

It will be mild steel, and I'm guessing that the entire frame will come out at about 300-400 pounds. It should be plenty stiff though, so I'll probably be able to remove a lot of the unibody sheet metal reinforcement... just not sure how much I'll be able to remove.

If I could get it down to around 2000 - 2200 pounds I'd be really excited, but as long as it is under 2500 I'll be satisfied.

The basic plan is this...

Front suspension will be unequal length A-arms. I haven't decided whether I'll fabricate my own or use some off-the-shelf bits and just position them as I want. Coilover shocks, rack and pinion steering, and a tunable sway bar will round out the front.

Rear suspension - I like the look of the Satchell link with a solid live rear axle, but I could be amenable to a three link as well. The frame design I've been building is for a Satchell link though.

Drivetrain - I plan on going with an all aluminum small block Chevy Gen III engine (probably an LS1 or LS6). The engine will be set back as far in the frame as I can manage without having it ride in the passenger's seat! It will probably be about a 12'' setback. The engine will be backed up by a 5 or 6 speed manual tranny and the rear will probably be a Ford 9''.

Brakes - big brakes all around with Hydroboost.

Body - I plan on doing some custom body modifications... forming my own rear quarter panels with fiberglass, etc.

Should be fun! And it will keep me busy until I can afford an RF! = )

 

[Ron Earp]

John,

You might want to just do a really good weld in cage. The Z we race has a full cage with 8 attachment points, petty bar, and lots of cross bracing. It is more than stiff enough for race duty, that is for certain.

Ours is at 2645lbs, but it could easily be lighter. That is just the race weight and there is no point in taking more stuff off the car since it'd be under weight. I think with a GM ally engine in there it'll be light. In fact, if you are really going to build the tube frame and use glass panels, well, you're already on the road do building something like a Prod SCCA car - you should just go ahread and build at least the car to those specs and if you want to go racing you'll be most of the way there.

R

 

[Paul Thompson 'Hooligan']

Build as light as you sensibly can - if the rules specify a minimum weight - at least you can add weight to the car where YOU want it which can often help balance a car's handling. I have seen a car over here with a quarter-inch steel plate across almost its entire underside in order ro come UP to minimum weight. Must have given a low c-of-g though.
/ubbthreads/images/graemlins/smile.gif

 

[Ron Earp]

I agree with you Paul on getting the CG and weight low.
We can't get the weight much lower, maybe 75lbs if we could remove the dash and wiring harness (illegal), although we've got poured lead in the bottom portions of a couple of tubes to balance and add weight.

I've seen some nifty things - 1/2 steel gussets for cages, 1/4" plate 6"x6" to mount the Master ff switch, cast iron section of pipe for exhaust (gets that weight really low down), and sort of like yours - 1/4" steel "floor pan repair" plates!

R

 

[Ross Nicol]

Ron this was the 240z race car before I sold it.A great car.
Ross

 

[Paul Thompson 'Hooligan']

Hi Ron /all

Yep - Retro cars are cool!
We have come across a few on the hills - like these two at Gurston Hill climb. The 'Z-Engineering' car was especially nice, but was unfortunately totalled when driver lost it near the finish and hit a wood pile alongside the track. /ubbthreads/images/graemlins/frown.gif

Flippin quick though and sounded just awesome..

 

[Ron Earp]

Nice looking Z's fellows! I like them!

I've always been a Z car fan, no matter if using the original lump or some V8 power, they are fun cars. They can handle very well with attention and can make decent power. That first one you got there Paul looks like it was modded fairly heavily!

We've got a big side exit exhaust on ours and it sounds awesome! I typically shift it about 6800-7100 and it is really running well then with a nice exhaust note. With the tire/gear/rear that puts us at 141 at 6.9k, we'll have to numerically drop the rear ratio to run Lowes Motorspeedway as we'll need more top end to hang on a 3/4 NASCAR oval we run before diving into the infield for the twisty bits.

 

[John]

Hey Ron,

I do plan on building it to be tech legal for SCCA. I've never done an SCCA event, but I could see getting into it when I build the car. I'll need to consult the rule book for all of the specifics, but as far as the frame goes I'm doing my weight estimates using the required wall thickness for such a frame.

I understand that the full spaceframe isn't necessary by any means and is certainly overkill. I partly want to do it just as a project to help build my skills... partly just to wow people... and because I would have to do a lot of frame modificaitons anyway to get the suspension setup as I want it.

I think I might have a lead on a 240z... will post back here if it materializes.