SteveK

For what its worth change them. They may look straight but stick them in a drill and spin them up and check for wobble with a dial gauge If you try and straighten them, you'll spend hours and still wont get them right, (got one of those tee shirts somewhere) then they wont seat properly and consequently wont seal properly, then you run the risk of melting one (or the seat) under load due to gas bypass, bits fall in cylinder and rather than spend what $100 on new ones you'll be building a new bottom end.

Does anyone know if 12 second Norm dude chap is still running his car and does it still make the 12's Someone mentioned that it was a bored and stroked L6 using the diesel crank

Why Give specific empiric engineering information, not just a NO!! On several occasions I have re shelled/re ringed and even done a complete rebuild using fresh components and then driven straight to a drag meet. I am in no way comparing my set up to a race set up but if its a bad thing, how are race engines broken in, do you see top fuel dragsters running around the local Kwik Mart car park with a sign on the back saying "running in please pass" Yeah-ok race engines are designed to be disposable and stripped down after every meet. So what we are talking about is an effect on longevity of the engine, but lets try and dispel the old wives tales and think science here Anyone got any hard cold data to say one-way or the other Plus, It is not unknown to "pamper" an engine and glaze bores or burnishes bearings As far as I am concerned as soon as the cam has bedded in (few minutes) its fair game. If it breaks then you got something else wrong

So I guess putting a completely rebuilt L28 (fresh everything) running it to the local drag strip (50 miles) and running several mid 13's isnt recomended then:stupid:

Why are Fel pro's poor? I built my engine around a 1mm gasket (felpro) a little while later we had to strip the head off (inducted a rivet from the air box into number 6 and bent a valve) I decided to put a 1mm HKS on for a trial and from that moment on had issues of water leaks, poor compression and loss of power. I stripped the head off after a few meets to fit new springs (a set doesn’t last long at 7500 rpm and measured the HKS, using a dial gauge on the valve it was 1.18 mm and using a calliper on the bore yielded 90.5 where as the Felpro was a true 1mm and 88.5 mm bore, all of this equated to about 1.6 cc increase (about .5 of a compression point). Also when we designed the engine, the compression was specified at 11:1 and the squish area was engineered to 48 thou (pistons 8 thou under deck and a gasket of 40 thou or 1mm = 48 thou) altering this with the HKS completely changed the characteristics of the engine. Whilst we had the HKS on we never achieved better that 13.8 on the quarter (20 runs) Now we have a fel pro back on, we are back on form again running 13.4 quarters, 4.72 seconds 0-60 and in excess of 250 at the fly with no leaks, plus they are a damn sight cheaper than a steel which is more suited to forced induction or really big compression blocks engines.

Zsaint this guys had 4 correct answers and 1 rather strange and uncharacturistic reply from JM -- hardly as you would put it "all kinds of answers"

When folks say that the lobes should be straight up, they mean that as a pair they should be as upwards as possible -- think Mickey mouse ears

260DET spot on mate 6 months ago I had my crappy euro damper disintegrate and fall off (split along the keyway) luckily I was only doing 5mph but earlier (5 mins before I was doing 135) …. It was a brand new one. The Euro damper was a cast item designed by Nissan to be mass produced and serve a purpose, the moment you begin to tune a car beyond manufacturers limits then a component level rethink is required. Several companies do good quality dampers ATI (my preferred) is an elastomer damper used on race applications world wide but not cheap !!!! We did comparative dyno runs which showed some of the shortfalls of the euro damper verses ATI-- the results were very revealing, gaining as much as 4 HP in one area and an overall gain right the way along both the torque and power curve to 7000 "How can a crank damper improve power" because it is tuned to dampen out the parasitic harmonic vibrations, letting the engine run smoother and more efficiently, plus with a quality damper you get the most important factor --a degree of security in knowing you have the best, those vibrations can destry a high reving engine in a heartbeat. Don’t forget to plan for a good exhaust system; all of your hard work can be fruitless if you bolt on any old tubular manifold and system. The Nismo chromed steel, inch and 5/8th 6 into 2 unit is good but needs a well thought out collector to work to its optimum, look to converge the pipes somewhere at the back of the gearbox (600mm or so), any less may loose you power/torque. Once again this is based on dyno time and experience, we saw over 20HP gained by the use of a well-designed collector. Carburetion ---huge subject. Some folks run SU’s and make great power .. Guy on here (Norm I think) runs 12 second quarters using SU’s. Most people get a set of triples and slap them on without thinking, air speed, chokes, ram pipes and air boxes – once again we saw huge differences between open ram pipes and cold air induction – like you wouldn’t believe. With a performance cam you will need good quality springs and valve retainers etc, you don’t want valve bounce if you intend to rev the engine. I can also recommend stainless valves with 3 angle seats. Head gasket type and thickness is important, there are various ones around varying in thickness from 1mm to 1.4 mm --- this of course changes your compression ratio (can be a good or a bad thing) I use a 1mm metal Gasket from HKS, as the engine is designed around a specific CR and squish area, this needs to be planned for. Chamber volume and consistency of chamber volume is critical, choice of piston, ring, bore finish, bearings etc all need to be thought of, it’s a long list and a forum is not the ideal place to build a definitive “must do” list. As jmortensen said you could do al lot worse than buy "How to Modify Your Nissan/Datsun OHC Engine" by Frank Honsowetz.

Hi Darkstar You choice of engine needs to be considered in line with the type of driving you are most likely to be doing Fast road, track, drag etc and engine configs may/will differ for all of these Don’t forget that the 2.4, 2.6 and 2.8 are all pretty much the same animal, are all closely related to each other, essentially with different bores and STROKE combinations and some as yet un quantified changes to block design (the absolute benefits of which are yet to be agreed upon). There are varied opinions regarding block strength verses the different blocks but I would say that which ever option you choose, over bores (3.1, 3.2 etc) are not without risk due to instability/porous blocks etc. What’s wrong with the 2.8.... it can be made to rev to reasonable levels reliably, with a little care and attention, and make good power in the right hands, enough to embarrass the occasional BMW and Porche driver :classic: The N42 and P90 heads are crackers and can yield good results with the right valves and chamber set up. Regarding Big Sam’s engine configuration (its a relatively well know car here in the UK) ... this has changed several times over the years (as has big Sam) the current engine config (last I heard) was attributable to one of the best L series engine builders around (now lives in New Zealand) --- Tim Riley. Big Sam utilises a steel billet crank, Cosworth pistons etc and don’t forget (no disrespect), there are cars of equal/greater stature around today, although people sometimes forget where the Z came from. The owner of Big Sam is a member of this forum and occasionally chips in (not often enough Nick) IMHO I wouldn’t necessarily agree with a 270-degree cam, I have seen bigger duration cams (300) work well, with not much more than stock lift. Don’t forget other factors in your quest for speed Brakes, the stock brakes on a Zed (not Zee) are prone to fading under enthusiastic driving. And as you mentioned Big Sam , one of its greatest tricks was the handling advantage it had over its rivals So suspension/handling will need work, as they were not particularly good from the factory let alone after 30 years.

I opted for total seal rings on my build up last year, after serious research I went for the top ring as gapless and the 2nd ring normal --- I was adviced to do this as it has been known that if the gapless is used on the second then even the smallest of leakage past the 1st ring can be stopped dead on the second and then the pressure build up can unseat the top ring causing issues. 1 year down the line -- we are still making 250 HP at the fly with a text book torque and HP curve

Consider using gapless rings (topseal) etc, I have been using them for the past year with excellent results.

Sometimes the product creates the demand friction modifiers Splitfire plugs Fuel vortex units NOS cubes All come under the catagory of "snake oil" no proven benefits but they still sell

Please dont forget that the "proud racing history of the Z car" goes way beyond the shores of America. There were and are significant racing appearances by Z's throughout the years in most areas of motorsport in many countries throughout the world. Check out http://www.zclub.net/forum/showthread.php?t=6109 Posts of note are those especially by Albrect, Legendary5, Ben240Z. Check them out, its my home club and very informative IMHO downdraft multi barrel single carbs are not a performance improvement over well set up SU's or triples --- 90 degree turns and all that

Welcome to the programmable injection club individual throttle body Injection is an excellent performance modification (been running throttle bodies with programmable mapping for a year now:sleep: ) but misunderstood by many. If that time is only a guess then thats hardly empirical evidence, however if it is based on a run then it would be good if you had a copy of the timing slip, as a sub 14 time would put you in line for the worlds quickest NA 2+2, bearing in mind that a Subaru Impreza turbo with 270 Hp only runs mid 13's and the legendary GTR Skyline out of the box runs 13.4 its important just how "sub 14" you are :cheeky:

IMHO To me it depends on whether you are building for power or just because you need a freshen up. If it is the former then first off dump those DGV's they are NOT performance carbs, I know they are expensive but a set of well built SU's will perform much better. Do that and you'll think you have a 3 litre in.

Check that your clutch is disengaging fully before you start stripping anything down. A partially engaged clutch plate will give you problems engaging gear. Check master and slave clutch cylinders, hoses and correct clutch adjustment/pedal travel

Indeed, there is a picture in my gallery that shows the general idea, courtesy of Motormec car prep who used it on one of their rally cars.

The engineers at Nissan must have figured that good handling would be so out of place in the US, that drivers would'nt like it, so they left them off LOL . Joking aside, strange that a componant so crucial to the handling of a car was omitted from a particular market. As far as I am aware, all European S30's had them as stock.

Curtis240Z Why?? I have been running triple throttle bodies with a narrow band for a year now -- car pulls 250 @ the flywheel and a 13.7 quarter. 99% of the time the sensor is out and unplugged, as the ECU holds true to the map then whats going to make your ratio go out? Running your ECU in closed loop will never yeild the results that direct map will, Get it dyno mapped and leave it.

Non stock FI responds well though, I use a cam with in excess of 300 degrees of overlap with throttle bodies and its fairly potent combination.

Thought this thread was dead, unsure as to the validaty of comparing data from such varying sources but well might as well contribute. 2.8 N54 block (no over bore) Custom height Flat tops producing 48thou quench Gapless rings N42 head, ported flow benched specifically for this injection project. Steel 1 mm head gasket Stainless valves 310 degree cam Triple Jenvey 40mm throttle bodies Emerald 32 bit ECU 252 cc injectors Carbon fibre 65 mm air horns Nismo 1 5/8 header and custom collector Electric water pump, fan etc 250 Hp @ the flywheel 205 @ the wheels Produced on a dyno owned by a guy who writes a column in several mainstream performance magazines for what its worth. 13.72 on the 1/4 mile