ozconnection

Sorry to hear about your bad news. May I attribute your troubles with a 'cheap' headgasket. Doesn't look like a genuine Nissan item because there are so few steam transfer ports open between the block and head mating surfaces. Just my 2 cents worth. Good luck with it mate. Cheers.

Lack of horsepower doesn't relate to lack of performance as you'd know Jon. Tony D had mentioned this in one of his posts in this thread with a guy in Japan who can smoke 'em at 2.5k in second. Its torque at these engine revs that makes the car feel good to drive. In terms of low horsepower readings with my engine can I suggest; 1) Stock L28S cam, it has only 240 degrees seat to seat duration inlets and 433 inch valve lift both in. and ex. 2) Camshaft advance 8 crankshaft degrees 3) Stock N42 head 4) Stock compression 8.3:1 5) Over 200K kilometres bottom end 6) Automatic trans L4N71B 7) Air/steer 8) Choked down 450 cfm Holley 9) Arizona inlet manifold setup for dual plane induction 10) 2.5k high stall converter Several of thse features will be corrected shortly, so stand by.....

That's solid advice, cheers for that!

I don't think I've been very clear with my last post. The engine is still original, N42 head and all. The testing so far is to baseline what I have at the moment. I have been giving camshaft selection a lot of thought. For this to work and be an exercise that not only convinces me but you guys out there as well, I need to be as scientific about this as I can. (Feels like science class at school all over again.....I may have listened a little!) I will be naturally testing my new Y70 head with the stock cam I have in the engine now. From there, I have already purchased an MSA stage 2 turbo grind camshaft. I won't go through the camshaft specifics, suffice to say that it's designed for an element of low down torque ie off boost with a low compression ratio and with sufficient valve timing and lift to give the engine a reasonable mid and top end. So mated with a NA engine with 10:1 compression and small, high velocity ports but with minimal camshaft overlap, it should be an 'interesting' if somewhat unconventional approach to what I want to achieve. So that's the theory! 'Change one thing at a time' is a reasonable way to go about this project, certainly this is the way I approached my Holley tuning for this combo. I've learn't a LOT about Holley's on L Series engines so if anyone wants to pick my brains on this topic, I will share what I know with you. So there, thats where I'm at and I'm sorry if things got a lttle muddled in my last post.

The idea was to take my car to the dyno to test the engine's output. The biggest trouble I had last time I was there was the rear tyres slipping on the rollers! We even tried strapping the car down with straps but even this failed to stop wheelspin. The open centre differential wasn't helping so we gave up on it for then. Rather, I'm now going to be using a 'G-Tech' an accelerometer. Cleaver little tool and can be used anywhere, anytime and is a hell of a lot cheaper than running the car up on the dyno. I ran it the other day with a mate of mine to see how my car was performing. 0-100km/h is 11.43 seconds 0-400metres is 18.2 with a terminal speed of 126.7 km/h This was up a slight incline with half a tank of petrol and another person in the car (75kgs), so my total weight was around 1650kg's (3633 lbs). To put this into perspective, I looked up the timing figures on the 280ZX non turbo cars, both auto and manual trans and my figures are pretty good compared to that car in standard form. One thing for sure is the ZX is a lot lighter than my car and the heaviest one I could find weighed in at 1307 kgs, nearly 350 kg's lighter than my test weight on the day. But, one thing is that the auto, on full throttle, activates the kickdown solenoid so the engine revs to about 4800 rpm on the one/two shift and around 5200 rpm on the two/three shift. If you can appreciate the fact that I'm tuning my engine for maximum low speed torque, then revving the engine this far isn't exactly conducive to me producing the cars fastest or quickest times. This 'slowing' at higher revs happens twice in a run to 100km/h or a run over 400 metres! What I'm going to do is a run using the 'detent', almost floored but just off the kickdown switch. The car shifts early but drops the engine right back into the torque band, in fact it never actually leaves it when driving like this! Knowing my gearbox and final drive ratios wheel diameters etc, the shift up points become 1st to 2nd at 35 km/h is 3100 rpm to 1800 rpm and 2nd to 3rd at 70 km/h is 3650 rpm to 2450 rpm. At 100km/h in 3rd the rpm's will be 3500 and at 127 km/h it will be the same as before at 4400 rpm. Can you guys see where I'm heading with this?? I can't wait until next weekend when I'll be trying this out. Give me your thoughts, I'd like your input. Cheers. __________________

Hell, we'd all be running around with a 650HP engine if it 'only' cost $6k!! Man, I bought some custom forged rods from PAR and a set of JE forged pistons and that's already $2.5K spent. Engine management and a set of pipes for that twin turbo setup will cost you....well lots! My P90 owes me heaps (lost count) and that's not including all the new valvetrain gear along the way. Then, there's the flywheel/clutch arrangement and the trans, like you've mentioned...maybe a tricked up 3 speed Jatco would be interesting instead of a manual....strip weapon?? I'm using a modified R32 turbo 5 speeder and that was over $1K. Even my Ross harmonic balancer was nearly $500.00, modified for crankfire ignition. I could go on and on but basically what I'm saying is that I've spent over $10K on my L28ET and haven't even started screwing it together yet. I'm predicting a reasonable 350-400HP. Good luck with your project. Oh, and was it for street, track or strip?

How on earth did you manage that?? Did you forget to change over and use the timing marker plate from the L26 on your L20? Weren't you just changing the balancer on a complete and running engine or am I assuming too much? How did cam timing get involved in that exercise??

Good points there. Another question could possibly be 'How healthy is the rest of the ignition system?' and perhaps 'What ignition system are you running?' Can you test 'smoother acceleration' on a dyno? What about fuel consumption? Any differences? Any more variables?

Personally, I like the idea of using a small port head on an L28. I'm about to do just that on my car to improve bottom end torque. I have a street car that weighs in at almost 1500 kgs and bottom end grunt is especially important to me. Many will knock the idea. Enlarging the ports is always seen as the 'right' thing to do. So now that idea is so ingrained in peoples minds, any engine with stock ports isn't really serious about making horsepower. Forget about making the ports smaller then...that's insane! As far as tuning is concerned, the small port head will promote air speed through the cylinder head into the chambers and cylinders. The valves are smaller and less shrouded. The compression ratio will rise due to the smaller chambers but this needs verification as some combinations won't work. Sure, a smaller port may be somewhat restrictive, however some minor bowl work and cleaning up of the valve seat area can improve things considerably. My solution is to put in a bigger camshaft if more top end performance is required. But you have to remember the reason for using this head in the first place. I feel that there is a definite lack of experience out there with this concept and L Series engines. Maybe you could beat me to it and tell us how it works.

Yeh, what he said

With a 5K old engine and with such good compression and the machine running smoothly, what else do you want? I wouldn't take the head off just yet. Have you tried a different oil, perhaps one with a slightly different viscosity or an additive and see if that has any effect. Valve stem seals if the culprit are easy to replace with the right tools and some compressed air. If you really want to port the head, go for it, seems such a shame to pull the head off to do something that perhaps you should've done before screwing it together 5K ago. Just my 2 cents worth.

Put the engine in 5th, put the handbrake on and chock the wheels. Now that should lock the engine! For an auto, use your rachet and hit the end of the rachet with a rubber mallet several times until the bolt loosens. My car is an auto and this is how I've done it in the past. Easier still is to run the car on ramps and drop the splash pan and access the balancer from underneath. Good luck.

Daniel, how much does that blanket cool things down? Any adverse side effects? I was thinking of building an aluminium plate between the carb and manifold but this seems to be better since the intake manifold if isolated from the updraft of heat as well. What is that material? Nice looking engine bay BTW!! Cheers.

That's a lovely looking car you've got there! Why are you changing the fuel pump? Are 12:1 mixtures too lean at 6000rpm and WOT on a stock L28ET? If I may say, you're 10:1 mixtures that I saw are probably a little too rich but that's not your fault, that's the fuel curve plugged into the ECU by Nissan who probably felt that without intercooling that was the number to run... If you could lean it out a little, I'm curious as to how much more torque and power you'd get at those revs. Great car mate, Cheers.

Extrude hone is the process you are referring to. A special medium is forced through the manifold to remove roughness and improve airflow. An EFI manifold like the one you have is an air only design. Fuel is added at the head/manifold junction by the direct port injectors. A wet manifold, such as one that uses a carburettor may benefit somewhat by keeping the manifold interior 'rough'

Found a few pictures of the LY28 crossflow head. The guy who's selling it wants $14K for it. :shock: Can't see a valve cover for it...anyone got one lying around? Not to be too critical, the chambers look huge. Good for a turbo setup maybe? Domed pistons for a NA setup? Thoughts/impressions anyone?

This is of course the theoretical optimal configuration we would all lust after but Xnke doesn't have these parts to play with if that's my understanding of what I read in his first post (F54 block with dished pistons and a 'soon to be milled' N42 cylinder head.)

For a street engine at this point in time....9.7:1 is just perfect IMO!

Links?

You guys seem to have a low octane rating compared to what we get down under. It makes me wonder if we're using the same values to measure our fuels??! For example, our regular unleaded fuel is 91-93 and our premium fuel is rated at 97-98 octane. Is this engine your going to build used as a daily driver or just a weekend blaster? That fact alone would influence my decision as to how much compression the engine will have. If you build yourself a high comp. motor and can't find the right fuel easily to run it, what a pain and you'll have to carry additives with you just in case. That, of course is not such a big deal if you just take it out on weekends and stuff. I touched on this point in my last post, that timing is often pulled out to stove off pinging. The real problem is too high a compression ratio. Yes, a bigger cam can and often does help this situation. However, the torque you lose at the lower half of the rev range using a bigger camshaft profile may become unacceptable to you. Just something to think about. I'm about to add a head to my L28 which is currently stock with an N42/N42 combination. When the new head goes on, I'll have a verified 9.94 to one compression motor. Even with our high octane fuels, I plan to run a fairly conservative camshaft so I'll need to be aware of potential ping. I don't really want to run a bigger cam since my efforts in this case are to boost low down torque anyway. I want/need to be able to run full ignition advance, hence my fairly 'low' 10:1 compression. I noticed that you've changed the rods in your engine. Obviously that incurs ar rod/stroke ratio variance. That has an effect on the way the piston travels through tdc and bdc. Based on that change, I'm assuming that you'll be running higher revs. Nice one. Another friend of mine built his L28 with even longer rare L14 rods and said the way the engine ran to the redline was very noticable compared to his stock L28 bottom end, with everything else being the same. You should have a nice engine when you're done! Cheers.

I dunno about what is said here, especially the part about valve overlap not playing a part in bleeding off cylinder pressure. My understanding of this situation is when the valves are off their seats, there is a pnenomenon called valve overlap breathing. At low engine speeds, when both the inlet and exhaust valves are open (and this value increases the larger the camshaft profile is, also in reducing lobe separation) the velocity of the air/fuel mix is easily reverted because a) the intake ports are often enlarged and because they are enlarged the air/fuel mix has little momentum and is easily pushed back out of the chamber by the rising piston. Then when its time to compress the mixture at low rpm's, there is less in there than will be found at higher speeds, when intake velocity increases, momentum increases and reversion reduces somewhat. To make up for this low engine speed related deficiency, the static compression is boosted in an effort to regain some low speed torque. Also at low speeds, the throttle may be partially closed, increasing the vacuum in the manifold. This will also reduce the available 'fill' of air/fuel mixture the engine can ingest and alter the volumetric efficiency of the engine. This will effect your dynamic compression ratio to something less than your calculated compression value. I had a friend of mine who built up a nice engine with 11.5 to one compression. The initial camshaft he chose was way too mild and it pinged like crazy regardless of what fuel he used. He began to back off ignition timing and saw huge losses in his power band so he was advised to go and try another bigger camshaft by an engine builder. He did that and found that the engine responded well to the new shaft and he was able to move his timing back to almost stock initial and total settings and the power was right there. He did have to use premium all the time but he was very happy with the end result. I think this is what you might end up doing too. Don't get too bogged down with the 'figures' (duration this, lift that) because its what works on your engine at the end of the day that matters, your 'combination' like it did for my mate and his combo. The rules suggested by others may get you in the ball park and you may be lucky and get it right straight away. Then again, you might not. Like I said, be prepared to try another cam if the first one ain't right. Good luck mate. Cheers.

Hmmmm. Take it easy mate.

Good luck

In my experience, it's the valve that hits the piston, not the piston hitting the head unless........ You need to provide us with more information on your bottom end, head and cam and how you set it all up so we can work out who or what to blame for your "tic tic tic".

No problem Daniel, I'm glad I am of some help to you. Your plugs look good from what I can see. You know your carb is working reasonably well then. I have never used colourtune myself, but I've heard they can be useful. I guess the best place to use one is on the dyno to test various rpm's and loads. However, at the dyno there should be a wideband exhaust sniffer that gets shoved into the tailpipe and that kinda makes the colourtune somewhat redundant. Still, at home setting up the idle, it would be a useful little tool. The best tool I ever bought was my Innovate Wide band. The second best tool was my Innova Equus 5568 Timing light. Within 5 minutes of testing my ignition with that, I found my distributor had advance problems. The degeneration was so gradual, that after I corrected the ignition, the engine response and top end increases were noteable.