Get flat top pistons or swap motor.

[beandip]

That's what I thought.

I didn't mean SU's were seriously complicated. Compared to normal Holley 4bbr carbs they are amazingly simple. But, in my mind, fuel injection is easier to work with. HOLLEY 4 BBR CARBS HAVE ABSOLUTLY NO BEARING HERE. Mabey for you the injection is easy. How many sensors do you have to depend on to keep the engine runing right ? With the SUs NONE . As for the predetionation with high compression na engines . You have the same problem with a boosted engine. Compression is compression reguardless if the engine is blown or not. Again Carbs are less complicated weather they are tripple Mikuni's or dual SUs. The advantage with injection is that they will make power and pass emissions , not all carberated engines can do that , especially if they are speed tuned. Another thing they will run good at different altitudes with out the need of tuning. The computer adjusts the mixture . Not a factor unless you travel from sea level to 10,000 ft. often. Gary

[Go240Zags]

Thank you all for your replies. I am thinking of getting some flat top pistons for the Turbo motor as I think the block is in good shape. I will sell the fuel injection and related turbo stuff, as well as the Borg-Warner 5 speed to help pay for the engine rebuild. And anything else worth salvaging off a beat body 280ZX 2+2 with poor interior. For my 12/70 240Z I will use my SUs which have Z Therapy rebuild kits, SM needles and N36 (260Z) intakes. I want simple power and it shouldn't take a whole lot of horsepower to get my lightweight Series 1 240Z moving. I am not sure about the P90A (hydrolic lifter head) and how reliable they are, but will try it out with a little milling if it is in good shape. Anyone know the proper part number for the pistons that came in the NA 280ZX. Again, thank you for the replies -- right now I am going for simple and may go the Turbo route in the future.

[thehelix112]

^^ i figured that i was low-balling the guesses... anyway, when i said "relaible" i didn't mean the engine was gonna blow, i meant that NA always has the power on demand... with a turbo, you have to have a properly tuned turbo for the application. there are lag issues, and sometimes one can be without power for some time. sometimes, if a car is course driving, the turbo car may be a complete dog because of the odd areas of the powerband that a turbo car has. for example, a car could be on a course with a lot of twisties and never make it into a proper RPM range to get decent power.

People make such a huge deal out of the lag issue with turbo cars. I personally don't know what the fuss is all about. I've driven a 3.0L SOHC turbo holden commodore (RB30ET) which started to make boost at 4000 and ran out of revs at 5500 and it wasn't that hard to drive quickly around a track. Just peg a lower gear coming into the corner. If you're really keen/talented (which I'm not) you can also hop back on the throttle while leaving the brake on through the apex to spool the turbo.

I'm not sure what you mean by `odd areas of the powerband'. FWIW my L28ET with a garrett GT35R (ie, 640hp capable turbocharger) makes positive manifold pressure at 3000rpm. How often do you see below 3000rpm if you're driving quickly anyway? Obviously a more moderate turbocharger would see boost even earlier.

anyway, i do agree that you can get more HP for the $$ with turbo, but to be honest, in going all out you will pay more with the turbo. my reasoning is: all of the tuning you will be doing to the NA car will have to be done to the turbo car as well, and then you don't have to worry about the cost of the turbo(s)

Interesting way to put it, but I agree anyway. A turbo car will be more expensive simple because there are more bits you need. Intercooler, turbocharger, wastegate being amongst the most expensive.

Go240Zags,

I'm not sure how hard L28ET exhaust manifolds are to chase up up there or what other parts you require for your L28E to run turbocharged but I can't speak highly enough of a turbo L. Your F54/P90 with dished pistons is running a very low compression ratio (7.38:1) which in a 240Z still gives quite reasonable drivability off-boost. I've only driven mine on 5psi thus far (ie, less than stock) and boy its a rush. As I said, makes boost by 3000, 5psi shortly thereafter and just doesn't stop.

However, all the other costs associated with getting the L28E into the zed might be prohibitive, namely, fuel injection issues: lift pump, surge tank, high pressure pump.

So you have to weigh this up against the work involved in raising the compressino of the F54/P90 engine to work in a N/A application. I would happily swap you a high compression L28 for your low compression one. F54/P90 L28s are like hens teeth over here.

Dave

[chickenwafer]

When it comes to street applications, a turbo will be cheaper than an NA, but for a fully built race application the NA will be cheaper. I agree with that.

But the turbo lag nonsense here is pointless. Unless you have some huge turbo that is outregously oversized for you application, you will not experience much lag. Yes, power can be more unpredictable and come in surges, but I kind of enjoy the feeling of thrust and breaking the rear tires lose in 4th gear. I know an NA motor can do that as well.......

This whole thing is starting to snowball into some NA vs. Turbo discussion and we all know those never end well. We will always be divided on the issue until some new technology comes along and renders the other one useless. Who knows, maybe rotary swaps into Z's will be the bext big thing?

And to Go240Zags- you're selling the Borg Warner T5 5-speed manual trans? I would love it, but I only have like 100 bucks to my name. You should be able to get some nice dough to finance the rebuilt out of that. Do you have another transmission to use?

Dave

[thehelix112]

Dave,

I agree this is a debate that will never be solved. Not to worry, different strokes for different folks. I'll stick with my turbo engines I think, though I do appreciate a screamer N/A engine.

Dave

[e_racer1999]

^^ya, definitely not a solveable debate.... but anyway.... i think i'm going to build my NA motor and i KNOW i'm going to build a turbo Z someday, it's just that i like having power when i push the gas.....

on the rotary point: i've actually had this thought in my head about a 3-rotor 240z swap........ i'm just too fond of the L-series, i guess...

[thehelix112]

Jason,

Just ensure you've got some revs when you push the gas and you will have power with a turbo or without.

Long live the L!.

Dave

[chickenwafer]

Jason,

I have toyed with the idea of a Wankel swap for some years now. It would somewhat difficult, but rotary-powered 510's are in creation so I don't think a rotary-powered Z is that far fetched. I used to own a Mazda RX-7 and I loved those rotaries........

Just think, a 13B with single HKS T51R turbo boosting at like 28 psi and sending over 600-hp to the rear wheels. Then you throw in the 3-rotor 20B were talking about and forget about it! Not to mention, if installed on a 240Z, the weight of the car and engine is so low it would be amazing. Ah yes, a project for some day after I win the lottery. Along with that will be a RB26DETT-powered all-wheel drive 280...........

But just as the other Dave here, I do appreciate a good screaming N/A as long as it revs nice and pulls hard. Both engines have advantages and always will, it's just how it is. Bt for my daily-driver, it is just plain cheaper for a turbo to get more power. If I had a race Z, that would be another story.......

Dave

P.S.- I think it's great how we can have a civil, adult discussion. We can have different views and not go at each others throats which you see so much on other forums (mainly Honda/Acura forums with pimple-faced high schoolers). This is a great place.

[e_racer1999]

^^most definitely.... just make sure not to mess with alan or carl..

anyway, a 3-rotor is going to be in the works in the future....

[thehelix112]

Why settle at three? Nick yourself a quad-rotor. 2.6L. Personally I detest the sound of rotaries. I appreciate them from an engineering point of view and am in awe of the power they make, but I know I would get a shock going from the reliable L to a rotary.

`What?! It blew up AGAIN?!'

Dave

[chickenwafer]

Rotaries only become unreliable when you turbocharge them. I had an NA 2nd gen (FC) RX-7 go for over 180,000 miles of hard use without a single rebuild. But, I had a 3rd gen (FD) RX-7 blow an apex seal at 81,200 miles. Mine was a single turbo boosting at 22 psi.

And I also dunno about that reliable L-series comment, Dave. My carbed L26 is as reliable as an American politician. Vapor lock, dieseling, and plain old stubborn-ness plauges my L-series. My FC was more reliable, rotary and all. Oh well, we have all had different experiences.

Dave

[e_racer1999]

^^the l26 is a known dog, but with a decent tune it will purr...

sure the l-series may be a little temperamental at times, but i have yet to see a blown l-series.