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3.1L powah!


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well all..a friend of mine wants me to build him a 3.1L engine. I've read the howtos on the Zhome and feel really comfortable when working on the L6 engines...i got a partsheet that i think i'd like the board to go over..

 

(its my practice to sit with someone who's engine i'm building and set a goal and work out the parts to get there instead of getting parts as you go along)

 

here's what i figure so far

 

F54 block 3mm overbore

LD28 crankshaft

240Z rods out of 1973 240Z

240SX KA24E pistons (89mm)

E31 head w/ 1mm oversize valves & port/polish milled to 40cc combustion chamber

2mm HKS big bore head gasket

HKS flywheel

cam 270/280 w/ .470 lift

??triple weber/mikuni or fuel injections?? * all aluminium linkage if carb chosen*

MSA 6-1 header

2.5inch straight back

 

transmission ZX 5 spd w/ 3.90 LSD R200 diff

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I probably am in no place to give advise on engine combinations, but I believe if you want to use the E31 cylinder head then you will have to use carbs or do some additional head work to have the fuel injectors to fit. guys correct me if I'm wrong...

 

eric

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hmm right...ill have my buddy contact you about the F54 block if he's interested if not i just might =)

 

nice candy watermelon color Brad!! looks really good...even w/ silver engine bay... =P

 

how much would you sell the rods & block for? I want to build a roadrace 3.1 for myself also

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The engine bay is now black. Some day I will paint it green like the rest of the car, I think I would of trash the paint when doing all the fitting and work in there.

 

As for the block and rods I would take 150$ for all of it but, keep in mind that I live in Canada just above North Dakota so shipping could cost a lot, depending on what state you are in.

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shipping will be more than the lot...

 

i live in southern cali...argh

 

whats the condition of the block? and also..where'd you get that beautiful green?

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Hmmm, looks like my motor minus my P-90A! (well, I sold it so I don't have it anymore)

 

First, where are you located?

Second, what are his overall goals for the motor?

Last, you realize the KA24 pistons are not always flat-top and will mostly likely require some milling....been there and done that.

First, the E-31 isn't really suited for the 3.1, esp. not with a 40cc combustion chamber. You realize that is a VERY HIGH compression ratio? Is this race only?

What is his budget?

Those all factor in on a very large scale to what the end result will be.

To do it for the cheapest route, I suggest the N-42 head with a good size cam and decent fuel supply,(carbs or FI).

I'll reserve suggestions till we know more about what this guy wants.

-Bob

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The F54 is the late 280ZX block which is siamesed between cylinders, right? Some builders would prefer to use the early 280Z block (N42?) for it's higher nickel content and unsiamesed cylinders. The siamesed cylinders distort in an "unround" fashion at different temperatures and should at least have the final honing done with torque plate and at operating temperature. This is true for any high performance application, even turbo's.

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The F54 is the late 280ZX block which is siamesed between cylinders, right? Some builders would prefer to use the early 280Z block (N42?) for it's higher nickel content and unsiamesed cylinders. The siamesed cylinders distort in an "unround" fashion at different temperatures and should at least have the final honing done with torque plate and at operating temperature.
Very true. I suggest the F54 for the 3mm overbore solely based on the fairly large amount of material that is being removed. My thought has always been that the siamesed block will have some extra material, at least between the cylinders. The hope is that translates to more material all the way around. To an extent it is wishful thinking. However, I would be surprised if the rigidity of the block is not impacted and the siamesed block helps minimize that impact. Again, only refering to the large 3mm overbore to get the "3.1L"

-Bob

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hey i need someone to clarify if teh N42 head came with fuel injection already setup on it? if so I'd like to set the guy up with a Z31 FI setup with 610cc injectors using a high compression setup N42 head...i realized unless he was going carb 100% E31 wouldnt be good

 

but if he goes carb...E31 is best choice for the application

 

can someone plz clarify?

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90% race? And only a 270/280 .470 lift cam? Why?

Why not go for something like .500 lift, 300 duration? If you are serious about power, I highly suggest calling Sunbelt. They built John C's motor, and put a cam in Dan Baldwin's motor, both strokers, and produced very good results. I think Dan paid on the order of 1000-1500 for his head work,(he had them do some minor port work, setup the cam, etc.. money very well spent in my book).

But this?:

fuel system: I've brought it down to twin downdraft webers setup for blowthrough design backed by a SDS EFI with 500cc injectors, straight EFI with 500cc, or triple 46mm webers..

Twin downdrafts? Why? The intake charge has to make a 90 degree turn, then a 45 and another 45 before it even hits the regular intake manifold? Not only that, you have the myriad of jets to deal with. If you are going to deal with jetting a carb setup, stick with the sidedrafts is my suggestion. Dan Baldwin can give you a rough ballpark for his cam/head and sidedrafts. I can provide you with a guideline for 40mm's and the cam you are using.

My suggestion? Full EFI with a standalone controler. You have far more control over the motor and its fuel with FI and something like SDS vice carbs. Better idle, likely better response, etc.. And the E-31 being the best for carbs? That is like saying is a Chevy best for towing? It really really depends on how it is set up. The E-31 in "stock" form has smaller valves and a somewhat restrictive design. It is a closed chamber design, but a fair amount of work must be done to realize the horsepower available. The N-42 on the other hand is fairly good right out of the box. It depends on your experience with Datsun heads. By your questions, I would say not very much, so I would suggest leaving that to someone else. Rebello is an option and they most certainly know what they are doing, but I personally prefer Sunbelt. They have their new cam profile and it appears to be working very well. If I wasn't switching to the RB motor, I would have a Sunbelt prepped head on my Z right now. Take a look at Dan B's dyno charts,(posts here as Dan Baldwin). Pretty impressive for a stroker.

With all the above in mind, here is my suggestion.

First, you already have the bottom end taken care of. Cylinder head, get one from Sunbelt. I suggest a N-42 prepped by them to yield the CR you want and the powerband you want. Expect ~$1500 for that cost, but money very well spent in the end.

Next, I would suggest FI with either the stock 280Z/ZX manifold or some custom setup. There are lots of guys here who have monkeyed with the stock FI to get more power, mostly the turbo types so ask on the turbo forum,(or the EFI forum). You can bore out the throttle body to get a bit more aiflow, plus fit larger injectors. That coupled with a speed density or MAF,(a bit more expensive), system will work wonders.

I think you could find 250+ hp with that setup, likely near 300 if done properly.

-Bob

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Originally posted by Bob H:

Hmmm, looks like my motor minus my P-90A! (well, I sold it so I don't have it anymore)

 

First, where are you located?

Second, what are his overall goals for the motor?

Last, you realize the KA24 pistons are not always flat-top and will mostly likely require some milling....been there and done that.

First, the E-31 isn't really suited for the 3.1, esp. not with a 40cc combustion chamber. You realize that is a VERY HIGH compression ratio? Is this race only?

What is his budget?

Those all factor in on a very large scale to what the end result will be.

To do it for the cheapest route, I suggest the N-42 head with a good size cam and decent fuel supply,(carbs or FI).

I'll reserve suggestions till we know more about what this guy wants.

-Bob

Bob, this motor is 90% of the time used to be a race motor and will use 96 octane gas..just a sunday circuit car mostly to show em what a old datsun can do with mostly factory parts..the only non factory parts will be the fuel system and the cam...

 

Im located in the San Fernando Valley (818 area code)

 

I'm more of a private engine builder; as i said before, I sit with whoever I'm going to build an engine for to find out what goals they'll have so there are no surprises...from the beginning to the end I'lluse the parts that will get them to their goal or setup stages if their budget doesnt permit an all at once build...

 

The KA24E (single cam KA24) are all flattops thats why im going to build the engine using those pistons. With the 2mm headgasket the compression should only be around 11.5:1 .. which is still semi streetable w/the cam i've chosen which will be ground to these specs: 270/280 .470 lift 110* LSA

 

I chose the parts I did for this guy because i figure it uses the most ridged stock offered parts there is...

 

fuel system: I've brought it down to twin downdraft webers setup for blowthrough design backed by a SDS EFI with 500cc injectors, straight EFI with 500cc, or triple 46mm webers..

 

anyone got any suggestions?

like i said: 80 or 90% circuit spec car and 10/20% streetcar

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Ditto what Bob said regarding having headwork done. Sunbelt rebuilt, ported, did some mild cc shaping, and installed a 302deg/.550" cam for my application, which is pretty similar to what you want. BTW, the KA24E pistons are dished, it's really more like a .019" raised ridge around the edge of the top of the piston. Have it machined off, this will give you more flexibility on head gasket thickness. My unshaved pistons stick up .022", removing the ridge would reduce this to .003" without really affecting compression ratio. You might also have the pistons notched for valve clearance, as with my cam I've only got ~.045" min clearance between the pistons and intake valve, even with the cam timing slightly retarded. I have no experience with downdraft Webers, but have heard from reliable sources that they're not as good as the stock SU carbs. I got a decent boost in high-end power when I switched from stock 1 3/4" SUs to 2" Jag SUs, but nothing like what I got when I went from 2" SUs to 45mm 3X2 carbs. If cost is an object, I'd recommend a used set of triples. Otherwise, FI with triple dual throttles.

 

I guess 11.5:1 might be OK on 96octane race gas, but Norm (resident giant-killing 1/4miler) has had piston ring lands fail (due to detonation?) above 11.2:1 on 93octane pump fuel. You might consider 100+ octane race gas. Or you could find out what flavor VPRacing fuel John Coffey is using in his 13.?:1 3.0 liter race engine, but you might want forged pistons at that CR level. I'm running 10.8:1 CR on 93 pump fuel at the moment, no problems.

 

Here's a link to rear wheel dyno results for my car (I can never seem to get these to appear in my posts): http://www.classiczcars.com/photopost/showphoto.php?photo=2274&papass=&sort=1&thecat=500

The leaning out at higher rpm has been cured with smaller air jets since that dyno run, which netted me 5 more hp (went from 228 to 233 on those dyno runs).

 

It is a lot of fun to outrun Z06s, Viper GTSs, 911 turbos, Cobra replicas and the like in an old Datsun:)

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VP Racing C12 - 108 motor octane leaded.

 

BTW... I questioned Jim about why leaded fuel when I'm running closed loop. Wouldn't my $220 Lambda sensor get fouled up? Jim's reply was that O2 and Lambda sensors get lead fouled only from idle and low speed operation. I can expect to get about 18 to 24 months out of the sensor before it will have to be replaced.

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Hey Dan,

 

you wrote:

I'd recommend a used set of triples. Otherwise, FI with triple dual throttles.
You don't have to go through all the expense of tripple throttle bodies for FI. Get a late 280ZX inatake manifold, and port match it to the head and gasket. Get a 240SX throttle body, and make a 1" spacer for it. Port match the spacer to the intake manifold, and that's it. You can probably do this for less than $100. WAY cheaper than multiple throttle bodies. Not a sexy though. No linkage to mess with either, you can use the stock Nissan linkage. You can also use the stock fuel rail, regulator, and turbo injectors if you need the extra flow. Run all this with a MAP based FI controller, and you will have total control over fuel at all RPMs and manifold pressures. Beats the livin' sh*t out of carbs (IMO)!

 

Pete

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I said dual downdrafts because i was going to convert em to blowthrough / throttle body operation ... but the fuel injection just sounds so much better everyday ... especially a SDS setup with sequential injection & a GM HEI/distributor ignition....the N42 head w/ 2mm oversize valves a .500 lift 292 duration cam would still let the guy street the car occasionally w/o to much trouble but still give good power.

 

Also I'd prob use a GT-R fuelpump w/ 500 cc injectors just incase .. its better to have more fuel and not use it than less and blow something up right?

 

heres a revised parts list

F54 block 3mm overbore

LD28 crankshaft

240Z rods out of 1973 240Z

240SX KA24E pistons (89mm)

N42 head 2mm oversize valves port polish and cc work by sunbelt

2mm HKS big bore head gasket

HKS flywheel

cam 292 w/ .500 lift

SDS Fuel injection

MSA 6-1 header

2.5inch straight back

ported 240SX throttle body w/ a 3/4 inch custom spacer

 

balance and port match everything for best flow possible

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