l28 rebuild

[Guest Anonymous]

As a lot of you probably know i've aquired a turbo block for nothing from Genocide (penguin X)...This winter im tearing down the block and stripping the turbo parts off of it to make a n/a 2.8l for my 240z (don't worry i have a plan for the turbo equipment too).

 

This is my plan...

 

-l28 .020 overbore

-l28 flat top pistons

-turbo connecting rods*

-balanced

-redoing the head with a new cam* (E88)

-resurfaced flywheel

-5 speed from the '72 (unfortunatly the turbo was auto)

-new clutch

-1mm head gasket

 

My goal is to obtain about a 10.5:1 compression. I want a high revving engine and am willing to sacrifice low end power and driveability to obtain it. What cam will suit my needs? I was also wondering if i should use the 240 rods instead of the turbo ones...is there any benefit, will i beable to achieve 220 hp at the flywheel?

 

My plans for the turbo are to put them on a 79-83 zx, and supe it up as my daily driver...can you say saweet?

[Cruez]

I did a somewhat similar project... the car is on my site...Still need to put a few more details on it though...

[Guest Anonymous]

need more info, bump

[Lockjaw]

The 240 rods won't work unless you run a different piston, but I have them in my turbo engine.

 

220 NA is going to take some work. You will likely have to go to a larger overbore than .020 over.

 

I would use a P79 or P90 head also, and mill them about 85 thous, and that will get you the compression you need.

 

What are you planning to use to fuel it? I would go with sidedrafts. For a cam, you will need something like the Isky L-490, Nissan L9, or equivalent. Crower makes a nice cam too, but I would have to get the part number of it from a friend. We had them grind it for us, and from 3500 rpms up, it pulls like a frieght train.

 

My friend ran this crower cam on a stock 280zx flat top bottom end with a p79 head milled 110 thous, side drafts, header, and 4.08 gears and he was running 8.40's in the eighth.

[Guest Anonymous]

i have tripple side draft webbers (40 DOCE)and an electric ignition. Im definetly using my E88 head, and i want to increase my redline to around 7400...i don't think i can afford a balance right now though, so is it going to fly?

[fl327]

it will buzz pretty good top end, remember a potent clutch and some 3.90 or 4.11 gears in that combo, and it will be a blast.

[Lockjaw]

Does your e88 head have the combustion chambers like an e31? If so, that will work ok. If it is the big open chamber, you will be down on power compared to the P series head.

 

Been there, done that.

[Guest Anonymous]

im going to have my head (E88) rebuilt this winter, its the exact same as the N series for combustion chamber (so im told), but the valves are smaller. But rumour has it that all zed heads flow about the same...Im not going to polish it, untill i decide if i want to keep it or not. with the combo i desire my compression will be about 10.17:1 sounds good to me.

 

can anyone else think of some issues i may find later on?

 

will i beable to run 13's with this combo?

[Guest Anonymous]

bump more info

[Bob_H]

Alright,

First, if you haven't already, read the thread in this forum about the best head for webers. It has something like 65 posts. Read it all. Then, and only then, come back and ask more questions.

Next, you want high rpm power, up through 7400 rpm. The E88 is an absolute waste of time without EXTENSIVE mods to promote good airflow. The comment,(which I made), about all heads flowing about the same was refering to the N and P series, NOT the E series. They require work, (in some cases not insignificant) to get up to the N and P series flow levels in stock form. I am not going to tell you what is required to get an E-88 to work well in the situation you want. If you are dead set on using it,(a mistake in my opinion), send it to a well known Datsun engine builder and pay them on the order of 1000-1500 US dollars.

Cam choice? You said you will be running 40 mm DCOE webers, a 2.8L block, an E-88 and want max power at high revs. You are starting with a poor combination and your cam choices are limited. See my suggestion at the end.

220 hp at the flywheel is achievable,(~180-190 at the wheels). However, take a really good look around at the types of motors that are putting that kinda power to the ground. Every one I know of save some race motors are strokers. The best 2.8 I have seen was 170 at the wheels, which is about 200-210 hp at the flywheel. Most 2.8L motors put from 140-165 at the wheels, or about 185-200 at the flywheel Yea, I know of a full race 2.8L that put 250 to the wheels, but you can't drive it on the street. It was built for a Bonneville speed record.

And let me address RPM. I cannot count the number of times someone writes me from my webpage and asks: "So how can I get my motor to turn 8-9000 rpm like the honda's?"

It is a fallacy that the L6 produces good power up high,(that kinda rpm), or needs to for that matter. However, in all fairness, you said 7400. There is no reason to rev that high to get the power you want. Above about 7000 rpm in the 2.8 and stroker L6 motors, the ring lands on factory type pistons, (i.e. not forged), start to pit and deteriorate from the beating they are taking. The rings flutter, don't seal as well, etc.. And forged pistons,(which combat the above) are not a good choice for something you will drive everyday.

Next, 240 rods. No, don't use them. You gain almost nothing and they are not worth the headache w/o a different piston setup.

You want 13 second 1/4 mi times. You won't see it with a L28 unless you put some serious time and money into your motor and everything behind it. First, with the webers, you must have someone who actually KNOWS what they are doing to tune them. Second, you really need at least the power levels you are talking about, which as I said above are hard to achieve.

So, what do I suggest for a 13 sec 1/4 mi car besides buying a newer camaro or firebird?

Go with a turbo L6. It is far eaiser to put the kind power down with a turbo than it is with a NA L6. Lets assume you are thick headed and absolutely have to do it with a NA block. Do yourself a favor and ditch your attachment to the E-88 head. If you don't want to do a lot of mods, the N-42 or N-47 are very hard to beat. If you are willing and know how to reset the valvetrain etc,(see the first thread mentioned), go for the P-79, P-90 or the Maxima N-47,(the last requiring valve work and combustion chamber work, again, mentioned in the big post).

For a cam, you are looking for something on the order of a .500 lift and 300 duration to get what you desire. However, don't try to turn it over 7k for the previously mentioned problems. You'll break your rings or the ring lands with enough time at that elevated rpm.

Next, BUDGET $$ for some tuning by a professional, on a dyno. Someone who knows webers. Otherwise convert it to FI or back to SU's and don't mess with the Webers.

I still say it is cheaper in the long run to switch to a turbo.

-Bob

 

Oh, USE THE SEARCH FUNCTION! Your question has been asked about 1000 times in various forms and answered even better than I have. The reason you had to keep bumping the topic is b/c it comes up about once every week or two, and people get sick and tired of answering the same question over and over again. If you are a "newbie", lurk and figure out how to use the search function. If you can't find it, then say you tired before you ask the question. Tell us what you serched for. Maybe we can serch with you and help you find older posts. I say the above b/c if you had really used the search function, you would have already come to many of the conclusions I put above.

[Guest Anonymous]

so how does norm do it with his 2.9 liter stroker?

 

12.95 i believe was his run, i was asking about 13.9

[Guest Anonymous]

does the 1/4 mile time still apply with the light weight 240z?

[Lockjaw]

My impression that Norm was running more than 10 to 1 compression, but you could hunt for his info and find out. Norm also was running more gear than currently available in stock nissan diff's.

 

Norm also had more displacement than 2.8 liters.

 

Bob put alot of info out there, and he is right about your head. Just because a head can flow doesn't take into account whether or not it has a good combustion chamber design. The P series and that maxima head all have a superior chamber design which inhibits detonation, which is very beneficial when running lots of compression on pump pee water.

 

One final thought. Who cares if you run mid 13's in an NA datsun if it breaks all the time?

 

I have a 2.8 I am putting in my 260 with a P79 and a big cam an su's. After I get it broken in, I will let you know what it runs.

[Guest Anonymous]

okay, so lets say i go to the n series heads, how much machine work am i going to have to do to get the desired 10-10.5 compression that i desire?...and norm is running 10.7:1 compression ratio, last time i checked.

[Drax240z]

None Eddy. The N series with flat top pistons will put you right about 10:1. A thinner head gasket will put you over your 10:1 goal. Mill any, and you'll have a bit higher.

 

Oh yeah, Norm. His times are not really a product of his engine. (I mean, they are, but not totally) He's been playing with suspension, tires, launches, etc. for ever, and I'm sure he has over 1000 trips down the strip. Once you have that type of experience, you can make anything fast.

[Guest Anonymous]

true enough. im planning on using a 1mm head gasket, so that will be about 10.2:1 compression. i might even mill off a milimetere to put me around 10.3-10.4. i think this should help me get to the desired 220 flywheel horsepower i want. Im getting my tripple webers tuned by a german auto repair shop, infact i'll probably have my whole engine tuned there. Im thinking about getting a 3.9 rear end out of a zed x or a 4.11 out of a turbo 200sx (automatic).

 

More info to come once i get more.

[Bob_H]

Not sure what you were asking about Norms car. First, Norm has been drag racing for years. He has changed the internal ratios of his transmission,(mixed and matched to get what he wanted), he runs open headers, high compression,(10.6:1 currently, but has been up over 11:1 before), and EXTENSIVE tuning of his SU's. I said it would require lots of time and money to get into the 13's. He has spent all kinds of time to get his car to that point. To give you an idea, I could go out in Norms car, and likely turn a 13.5-.8 in the exact same configuration he ran the 12.9 in. He knows what he is doing, and that is the extreme end of the spectrum. Did you take a look at what kind of head work he did to his N42? Serious stuff.

Next, stock with no shaving of the N-42. You will cause more problems trying to run that kind of compression. 10.5:1 is really too high for the street. 10:1 is really the practical limit for a street driven car since you can't always count on getting perfect 93 octane gas at each fillup.

Lockjaw put it best:

One final thought. Who cares if you run mid 13's in an NA datsun if it breaks all the time?

You can't put it much better than that. And really, to run the compression you want, the P series are a much better design. However, they require some not insignificant mods/work to work after shaving to get that CR. Are you willing to do that or pay someone to set your valvetrain and cam timing back up? It all gets back to time and money. And for the record, I have only been talking about a 240. To get the heavier 280 into the 13's is the same as trying to get a 280zx into the 13's w/o a turbo. Their weight is very close to each other.

You are dead set on that high compression ratio. Let it go, it will cause more problems than you care to deal with. If you chose to ignore those of us who have done it, expect it to break just like Norm's did. Remember, this is NOT a honda or a toyota. The cylinder head design just does not support that CR w/o race gas. Don't shave the N-42 if you use it. Run it stock with a good aftermarket cam. I recommend somewhere in the neighborhood of .490 lift and 290 duration or larger,(but not larger than the other one I mentioned).

Next, the difference in .1 of C.R. is worth a hp or two at best. I think,(recalling from memory here), that every full point increase in C.R., i.e. 9:1 to 10:1 is worth about 10-15 hp. So you might get 2-3 hp from the .2 point increase.

[Guest norm[T12SDSUD]]

Okay, here's the deal.

 

You really have to be willing to drive the piss out of your car if you are going to hit 12's.And unless you have perfect track conditions you must run slicks or good drag radials to hit 12's.

 

I could write a very long book on all the parts I have broken over 7 years of drag racing.I have WELL over 1300 drag strip passes on my car.

In one night I make more passes than some do in a year's time, so that is one of the reasons for my many blown parts.In fact I made 44 passes in one slow night at Wilkesboro!!

 

The high revs and hard shifts of an N/A car on the strip have ways of shaking things loose and grenading many parts.

 

If you are going to drag race get a VERY GOOD clutch(I run a beefed up Dual Friction Centerforce model) and be sure to Loc tite the Flywheel bolts,torque the harmonic balancer to 150 ft-lbs.and useLoc Tite,Be sure to Loctite the timing chain guide bolts also.I just upgraded my curved timing chain guide bolts from 6mm to 8mm after having them break or come loose for the 3rd time!

I also sheared off the altenator mount bolts at the block two different times so get some strong bolts and loc tite them also.

 

Your tranny will need to have steel shifter forks

installed if it is a later 81-83 model as the aluminum shifter forks will break in two and also install double roll pins on the shifter rods or they will shear constantly. Also make sure and get a steel face plate as the later trannies had aluminum face plates which allow the tranny to fail.

 

Anyway,stay under 11:1 CR on any street engine unless you have forged pistons or can afford to run afew gallons of 100 octane gas.

I had a very reliable 10.6:1 CR setup until I bumped it up to the 11.6:1 CR and it broke piston ringlands three different times.

 

I unknowingly ran 11.3:1 CR for three months this summer before breaking 4 pistons on a 1/4 mile pass in the heat of August.The piston dish was 3 cc's smaller than it was supposed to have been, but thinking that Nissan never offered any thing other than a 10.9 cc dished piston I never bothered cc'ing the piston dish until after it blowed up again last month.It was actually a 7.9 cc piston.When you grab pistons out of junkyard engines it pays never to assume anything.

 

I just finished rebuilding my motor back to 10.6:1 CR last week.

 

The 11.3 CR motor did manage a 13.2 @ 106.6 mph with open headers and regular street tires with a miserable 2.23 60 ft., so it could have managed a 12 sec. street tire run under perfect track conditions.

 

BTW I now run a stock geared 79 5 speed and a stock 3.9 R200.

 

My best run on the 10.6:1 CR 2.9L was a 12.88 @ 105.8 mph with an open header and slicks.

 

You should be able to hit 13.9's, but you will have to beat on your car to acheive this since it is the heavier 280Z model.

 

BTW, years ago I did manage a 13.6 @ 99 mph with a stock block 2.4L with my modified N42 head, so you can see you don't need lots of cubic inches to run really fast.

And finally, don't power shift an inline 6 Datsun motor or you will break the crankshaft in half.Oh yeah, I broke two of those in half when I used to run the 2.8L a few years back.Lift when you shift, the crank you save may be your own.

 

Later,norm

[Guest norm[T12SDSUD]]

Oh , reread yourpost where you were going to run this setup in a 240Z.

In that case you should have zero problems hitting 13.9's.

 

My 9.6:1 CR 2.8L with stock SU's ran a best time of 13.4 @ 101 mph with STREET tires and an open header.

 

Now that was with power shifting so figure 13.6 without the engine destroying power shifts.

 

Build it and shift at 7000 rpm and you should hit high 13's with ease.

 

Later,norm

[randy 77zt]

rebello build a 3.1l street engine with su's bored to 50mm.they have more power than my stock 81 zxt motor.rev good and idle smooth.but anything from rebello is not cheap.i have ran at thunderhill against another z with this setup.