Small port heads.

[Daeron]

/threadjack/

 

my buddy's 92 RS camaro (tbi 302 w/5 spd) blew a transmission one day and the only driver/vehicle combination that was available to rescue him was my dad in his NA 86 300ZX with a receiver hitch which I magically found in a junkyard. Incidentally, I have a tendency to find Z-car tow hitches in junkyards with my shins and kneecaps.... If anyone wants the tow hitch for the Z31 let me know, we still have it and its still wreaking havoc on unguarded shinbones at our shop...

 

To keep this a little more on-topic, does anyone know about any difference between VG30E heads from maxima to Z-car? Obviously radically different manifolds were used since the VG maximas went to FF layout, but I couldn't even tell you if there were casting families like the L-series or what. I am just curious; every time I see a VG SOHC head I am fascinated with it and I think of the old California Coffin and just can't get it out of *my* head that somewhere in THAT head lies lots of vroom.....

 

/threadjack off/

[ozconnection]

Y70 head is back home with me.

Needs a clean, found some random aluminium filings around the ports and it needs the rear welch plug put back in. Otherwise it looks good with the intakes having a lovely short side radius. The injector notches were also welded up by request to reduce port turbulence. New intake guides too. The exhausts were OK apparently. The valve seats look wonderful, I hope they flow as well as they look! The edges of the chambers need a little smoothing to remove the new sharp edge caused by facing the head. Just some small stuff but I wonder what I'd have to pay to get that done. I thought I paid enough in the first place.

 

 

[JMortensen]

Since we're using anecdotal evidence to prove our respective points, there are probably some people who have been around the Z scene for a decade or so who remember a friend of mine Tory who towed his Z to the MSA show, with his other Z. He then sold the towee at the show. The tower was a triple Mikuni'd ported head, cammed L28. The towee was a stockish 240Z. It was pulled on a tow dolly. I thought it was a really stupid thing to do because of the complete lack of brakes and the short wheelbase of the tow vehicle, but he came back telling me how great it worked out, and that he was able to climb the several grades between our city and the MSA show ~150 miles away at 65+ mph.

 

As for knocking that lip off the combustion chamber, looks like about 1/2 hour's work with some emery cloth and your finger, if that.

[kolonelklink87]

Since we're using anecdotal evidence to prove our respective points, there are probably some people who have been around the Z scene for a decade or so who remember a friend of mine Tory who towed his Z to the MSA show, with his other Z. He then sold the towee at the show. The tower was a triple Mikuni'd ported head, cammed L28. The towee was a stockish 240Z. It was pulled on a tow dolly. I thought it was a really stupid thing to do because of the complete lack of brakes and the short wheelbase of the tow vehicle, but he came back telling me how great it worked out, and that he was able to climb the several grades between our city and the MSA show ~150 miles away at 65+ mph.

 

As for knocking that lip off the combustion chamber, looks like about 1/2 hour's work with some emery cloth and your finger, if that.

 

As far as anecdotal evidence goes thats a neat counter-point yes

The truth of the matter is, of course, that we just wont know untill it's on the dyno... All we have untill then is anecdotes, contrast/comparisons and assumptions.

(from the look of that head) Dyno day is getting closer 'though

[ozconnection]

 

As for knocking that lip off the combustion chamber, looks like about 1/2 hour's work with some emery cloth and your finger, if that.

 

Yeah, I thought that too.

 

I might just add that these cars weigh 1450 kgs (about 3200 lbs) each, plus the trailer which I guestimate to be around 500kgs (1100lbs) so that totals almost 3400 kgs (7500 lbs), without driver. Now, how much does a Z weigh?

 

In retrospect, I think that what I did was prety dumb too, the weight of that trailer and car combo would've far exceeded the safe towing capacity of my tow bar arrangement, anything could've happened, fortunately it didn't. (Oh did I mention a flat tyre on the trailer on which I stuffed my original 30 YO jack with! Buggar!! )

 

Does anyone have a material preference for the welsh plug that goes into the back of the head. Mine was removed but not replaced. I heard that a steel one is better than a brass one due to 'sacrificial' issues. Is this true??

[Noddle]

Does anyone have a material preference for the welsh plug that goes into the back of the head. Mine was removed but not replaced. I heard that a steel one is better than a brass one due to 'sacrificial' issues. Is this true??

 

It should matter if you you anti-corrosion/ anti-freeze.

 

Nigel

[ozconnection]

It should matter if you you anti-corrosion/ anti-freeze.

 

Nigel

 

Yes, good point! Thanks.

[ozconnection]

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.

__________________

[JMortensen]

http://www.060calculator.com/ says 122 hp. That's the only calculator I could find for 0-60, and I would say it's a bit dodgy. You're doing 0-62, so add a few hp to the result. There are a lot more tools for the 1/4 mile, but you did the 400 meter which is just a bit shorter. Using a 1/4 mile calculator here: http://www.dsm.org/tools/calchp.htm it comes up with 119 and 138 hp using two different testing methods of ET and trap speed. These numbers should be at the wheel, but since 400 meters is slightly less than 1/4 mile they'll be a bit high. Let's use another dodgy assumption of 20% drivetrain loss which is probably a little high. 280ZX puts out 182 gross hp, so that would net 145.

 

You could cam it, but I think the results you'll end up with will be rather similar to the stock L28, unless you go really big, and then you'll lose your bottom end power, which was the point of the build as I recall. You could gear it and get a torque converter setup for a diesel and optimize what you have there. Would it be worth it though? I'm thinking not. Especially when you again look at the L24 dyno plot from the ITS car and figure that an L28 with a longer stroke and larger bore and the same size cam should put out about the same torque curve, if not have more torque lower than the L24 (theory borne out by it's lower redline), and a stock engine won't be as tweaked for high rpm performance as the ITS engine.

[ozconnection]

http://www.060calculator.com/ says 122 hp. That's the only calculator I could find for 0-60, and I would say it's a bit dodgy. You're doing 0-62, so add a few hp to the result. There are a lot more tools for the 1/4 mile, but you did the 400 meter which is just a bit shorter. Using a 1/4 mile calculator here: http://www.dsm.org/tools/calchp.htm it comes up with 119 and 138 hp using two different testing methods of ET and trap speed. These numbers should be at the wheel, but since 400 meters is slightly less than 1/4 mile they'll be a bit high. Let's use another dodgy assumption of 20% drivetrain loss which is probably a little high. 280ZX puts out 182 gross hp, so that would net 145.

 

You could cam it, but I think the results you'll end up with will be rather similar to the stock L28, unless you go really big, and then you'll lose your bottom end power, which was the point of the build as I recall. You could gear it and get a torque converter setup for a diesel and optimize what you have there. Would it be worth it though? I'm thinking not. Especially when you again look at the L24 dyno plot from the ITS car and figure that an L28 with a longer stroke and larger bore and the same size cam should put out about the same torque curve, if not have more torque lower than the L24 (theory borne out by it's lower redline), and a stock engine won't be as tweaked for high rpm performance as the ITS engine.

 

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.

[HowlerMonkey]

Unplug the kickdown switch and don't have the straps pulling straight backwards.

 

Better to have the straps pulling almost straight down and let the car run up on the rollers a bit rather than having it cinched down.

 

I'll be running a 1000+hp car on the dyno today and strap angle as well as where you strap the car is very important.

[JMortensen]

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.

What do you attribute it's lack of hp to?

[ozconnection]

Unplug the kickdown switch and don't have the straps pulling straight backwards.

 

Better to have the straps pulling almost straight down and let the car run up on the rollers a bit rather than having it cinched down.

 

I'll be running a 1000+hp car on the dyno today and strap angle as well as where you strap the car is very important.

 

That's solid advice, cheers for that!

[ozconnection]

What do you attribute it's lack of hp to?

 

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.....

[kolonelklink87]

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.....

 

Of was of the impression that these kinds of HP readings mean sqwat if you want to compare to another person, to factory or to boast...

even dyno figures aren't universal, 20hp can be gained or lost anywhere - big weight factor + skinny stock wheels, auto tranny, moisture on the road and air, air temp on the day etc etc...

these kinds of readings are not a science but a "guesstimate". They are however useful for comparing one setup to another when changing a single condition...

 

in science i beleive this is called qualitative data (as opposed to quantitative)

[ozconnection]

these kinds of readings are not a science but a "guesstimate". They are however useful for comparing one setup to another when changing a single condition...

 

in science i beleive this is called qualitative data (as opposed to quantitative)

 

Yeah, this form of vehicle assessment may be considered as crap. The same can be applied to desktop computer simulation programs too if we're looking for a debate. I do however, find some usefulness with both of these tools. I use them to compare and verify changes.

 

Now, at least fairly quickly, cheaply and convieniently I can go out and check out what the computer program has suggested has given me 20 HP on the road nearby with my other 'dodgy' tool, the accelerometer. Scientific, yes, qualitative, yes, to a degree.

 

If you choose not to use these 'tools' then what other options do you have? Seat of your pants maybe? Hell, we can all feel that can't we? But how useful is that in conveying to the next bloke how quicker/faster the car is now?? Not much. (read quantative). "Mate she feels heaps quicker...." Enough said.

[JMortensen]

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.

I think Tony D is talking out of his butt on this one, sorry Tony but that's my opinion. Even if you have a diesel that makes HUGE torque and doesn't rev past 3500 rpm, they also make HUGE hp. Here in the states guys are doing propane injection and changing the fuel curves, and adding big turbos. They're getting 1000 ft/lbs of torque, AND they're getting 7-800 hp to go with it. Since hp is a function of torque over time, you don't really get one without the other. Even a diesel Jetta still has 140 hp. You can have a torquey gas engine built like a diesel, but I don't think you're going to come anywhere near the results you can get with a diesel. Diesel fuel is better than gas at the job of low rpm, high compression, huge torque production.

 

Why am I bringing up the lack of power? Because you stated that it was an "original" engine. When I read that, I read "stock". Based on that I don't think my asking why your engine is down on power is out of line at all. Now that I see what you've done to it, cam timing is an obvious cause for the power loss.

[Tony D]

Then I'm full of crap on that one John. I did the conversion on Jeff Ellis' 1978 Fairlady Z in 1987 before he shipped the car to Florida. Last I heard he was working for an airline down there.

 

I could put that car in second gear and simply lay on the throttle and P195 60-14's would break free and boil. No clutch kicking to spin a donut, and it was all-in at 5500 rpms. The car was very drivable when short-shifted. Sometimes you can tailor a vehicle to a persons driving style, and while it may not be 'the ultimate setup in your mind' --- for the customer they LOVE IT!

 

There are several 'satisfied customers' with similar setups simply because L28 Manifolds used in sedans didn't fit well under the Z Hoods, or line up as needed, so I did several conversions like this. The engines were torquey at the bottom end, moreso than the big runner engines. But over 3500 and to redline the bigger runnered engines pulled harder.

 

Jeff sent me a letter and was very happy once he returned to the USA. The ability to lug the engine at 45mph in fifth gear made for nice mileage and overall he was very impressed with the results. And it still went 120+, so for him that was all that mattered.

 

Sometimes people need to put aside their predetermined thoughts on what is 'acceptable performance' and realize people want what they want, and if it's not what YOU want, then you have to live with it. This is probably one of those situations, John...

 

Feel Free to look up Jeff Ellis, maybe you can get his take on the car.

 

On the same subject, slipping links on the timing chain is a horrible way to kill the top end power, but it does similar things to moving the powerband around. Did that, too. Some guys loved it because they grew up with Hydraulic Liftered V8's that floated the valves at 4500 rpms and shifted religiously at WOT at no more than 4000 rpms. "Getting on it" for them involved a WOT run to 3500 and upshifting on the way to work most of the times.

 

I've said it before elsewhere: For about 85% of the people posting on these forums, you could substitute a Diesel Jetta engine into their Z-Car and they would NEVER know the difference. They take being shifted at 3K very well, and you can run them to 5K at 140KPH in 3rd gear for a hoot. Hell, I videoed it last time I had one in Spain!

[JMortensen]

Sometimes people need to put aside their predetermined thoughts on what is 'acceptable performance' and realize people want what they want, and if it's not what YOU want, then you have to live with it. This is probably one of those situations, John...

True enough. My point throughout has been to provide a counterpoint to the notion that putting a small port head on an L28 is a wonderful idea. As I said earlier:

I get the idea of the thread, I just thought maybe a dissenting opinion was in order. Choking down an L6 is in my estimation counterproductive, and as you point out, there are other ways to change the powerband without having to resort to smaller than usual ports.

I think my point has been made, so I'll duck out of this one.

[kolonelklink87]

Yeah, this form of vehicle assessment may be considered as crap. The same can be applied to desktop computer simulation programs too if we're looking for a debate. I do however, find some usefulness with both of these tools. I use them to compare and verify changes.

 

 

Woah... lots of passionate opinions flying around on this thread ^^ lots of debate is good!

 

I dont want to be taken the wrong way - my point was that almost all HP data is qualitative - that is not a bad thing... sorry i probably jumped too much into the science aspect...

 

This kind of data is VERY useful when comparing a known to an unknown (ie "stock" to "modified")... my point was that even dyno figures aren't reliable on the day but they do give you an idea in terms of percentage over how much power you've lost/gained per modification.

 

Your method is sound. as long as you keep the conditions constant and change one this at a time you will get a good idea of how much power you've gained... i was trying to illuminate that just because your calculations tell you this is ~122hp does not make it so- it is unnessecary to read into these figures too much unless is for comparison between data sets - which is what qualitative data is all about.

 

I'm not bashing this type of aquisition, i spend at least 10 hours a week preparing microscopy slides for a research group which has absolutely not quantitative component at all- that does not mean it is not scientific... engineers love set numbers because they deal with known parameters, when dealing wiht the unknown, often qaulitative data is the best way to go (afterall... if i have a numerical figure by itself and no scale to compare against its pretty darn useless).

 

Back to dynos - dyno competitions are always held on the same dyno due to the variability factor... someone result at one dyno shop is not equivlent to another persons at a different place on another day. in my opinion you are on the right track in terms of data-aquisition, you wouldnt learn anything more from a dyno that you can with the accellerometer(?) I'm pretty keen to get a look at it actually, maybe get one myself... too busy preparing slides atm though

 

(sorry i've been out of contact, heaps busy and in exams atm:evil: catch up soon)