Perfect Engine/Head/Carb/Tranny/Rearend Setup

[texasz]

I have been doing a LOT of reading on this website as well as a hand full of others and think that I may have figured out what is considered to be the best overall setup for a Z. Please work with here as I am very new to all of this and am only working off my notes from various people's opinions and tested results. I do welcome all helpful information as I would like to determine the truely best way to build up a Z car.

For starters you need a '70-71 Z car as these were lighter than the later ones.

Now for the rest...

ENGINE: an '81-'83 L28 non-turbo motor (this will have flat top pistons) which will be an F54 block and should have originally had a P79 head

HEAD: an '81-'82 P90 head (Does this head have brass rings?)

CARB: round top SU carbs

TRANNY:

a '77-'79 5-speed with a '77-'78 R200 3.9 rearend from a non-turbo car - this is the performance setup

-or-

an '81-'83 5-speed with a 4.11 rearend from an '85 200SX - this is the speed setup

From everything that I have read so far it seems as though this would give you the best results. However, like I said, I am new to this and am in the process of sorting it all out so any help would be great.

[2ManyZs]

Only thing I tend to disagree with is the rear diff choices. I'd stick with the R-180 rear if at all possible, just for the difference in weight. You should be able to find a 3.90 or 4.11 R-180 without too much trouble, there are a lot of racers out there selling them, and there are ways to get the R-180 with the gears you want out of a 720 4x4 Nissan truck, and a few of the 200SX's had them as well.

The P-90 head doesn't have the bronze valve seats if that is what you meant instead of rings.. They should have the hardened steel seats in the P-79 and P-90 heads as they were used with unleaded.

[Ed]

I must agree with most of your pics also. It definately looks like you did your homework. I lucked out and got a wrecked 81 non turbo. Ended up with the engine & tranny for $100 bucks. The rear end I'd keep a R-180, from what I've heard unless you plan to put some unreal amount of power to the pavement the R-180 can hold up to almost anything. I talked to a guy who builds drag cars out of Z's in Califoria. He puts a chevy big block in there and he said that the R-180 holds up no problem.

[ZmeFly]

if you want to be limited and not have that fast or streetable car, then by all means, stick with the carbed n/a motor.

if you must have an N/A motor then you should go with fuel injection, not carburetion. its a simple plain know fact that injection is better the carburetion any time.

the best engine in my opinion, would be a 83 turbo motor, upgraded turbo with upgraded injectors. more power, reliability, streetability.<~~is that a word.

however i do agree with the tranny selection and rear selection but would also stick with the R180 with a quaife differential.

just my .02

[Dan Baldwin]

I would (did) go with the N42 head, much higher compression without having to shave excessively. I have yet to see any objective info that the P90 is superior, I'd say there's not much between the two, performancewise, at the same compression ratio. It's just harder to GET to a decent compression ratio with the P90. N42 on a flat-top piston bottom end and you're at 9.8:1, vs. 8.5:1 with the P90. Then again, if you have a P90 and not an N42, shaving it .080 and shimming the cam towers would work as well, but I think you'd have to swap in 280Z valves.

My first choice for a stock Z tranny would be the '80 280ZX. First gear is tall, but the ratios are well spaced (though 5th is kinda tall, too). The 280Z/1979 280ZX tranny has a BIG gap between 2nd and 3rd. It does have shorter 1st and 5th gears, though. I have an '81-'83 ZX tranny, same as '80 but with an even taller 5th. Thinking of going to a truck tranny with better ratios. I still prefer my tranny to the earlier 5-speeds. Anyway, go here for ratios: http://www.geocities.com/z_design_studio/

Rear end: The best *reasonably-priced* option is the 3.70 lsd from the 4/87 - 89 non-SS 300ZX turbo. If you're going to be doing any serious track driving or autoX, you NEED a limited slip. You could swap in a 3.90 or 4.10 ring and pinion if you want.

IMO, SU carbs should be just fine up to ~185 or so rear wheel hp. In my experience they did tend to lean out at higher rpm, though. Now I've got 3x2 45mm triples, and shockingly enough, it's easier to start, idles better, and makes a TON more power. Ideally, FI is best. BUT, motorcycle manufacturers have taken YEARS to get their FI setups as good as their carb setups in terms of throttle response, and haven't gotten much (if any) of an increase in power from FI, either (mainly better emissions). And they are WAY smarter than you and I. In my opinion, SU carbs are very simple to set up, and triples aren't the insoluble puzzle they're made out to be (then again maybe I just got lucky w/ mine!).

BTW, if you're going to be doing a bottom end rebuild anyway, you should consider going the bored/stroked 3.1 liter route (L28 block, Maxima diesel crank, '73 240Z rods, 240SX/Hardbody truck pistons). Regardless of what you might hear, displacement RULES. 1) Displacement 2) compression ratio 3) rpm.

Good Luck!

[ZmeFly]

but you can pay as much as 500 dollars for a used one and no warranty at all. clutch packs are expensive, to replace.

with the quaife no worries and better selection.

now speaking of the N42 head i dont know if any of you know of Norm, he has a 71 240Z daily driver, with his engine made of junk yard parts.

its a small 2.9 stroker and with the N42 head and su's and hes turned a best time at the track of 12.92

he balances and hand sands his own pistons and rods and such. hes a true marvel at the track and on the street and in the Z world.

if you ever feel curious about going to the other Z site, you can ususally find him at www.Zcar.com and www.hybridZ.org

[texasz]

What's a quaife?

[Ed]

I believe it is a brand name. Kind of like Holley is to carburators or Good Year is to tires.

[2ManyZs]

A Quaife is a differential that uses gears instead of springs and clutch packs. It is similar to the Torson diff in that is uses helical gears to provide lockup instead of relying on the friction in the clutch type limited slips units. It is more similar to the Detroit Locker in that it provides solid engagement instead of having some amount of slippage, but the Quaife and the Torson are variable lock-up where the Detroit Lockers are either locked or unlocked.

http://www.quaifeusa.com/