how much power????

[260freak]

been doing a bit a thinking!

What sort of power figures would i get out of:

A F54 block bored out to 3.1

running P90 head with new cam (any suggestions?)

tripple webbers (or is their anything better?)

with extractors

5 speed

etc........

so all you hardcore z guys what sort of numbers would i be pushing? and has anyone done this?

[Gav240z]

I know a guy almost making 300HP at the flywheel with SU's. Using this very set up, I can't tell you the specifics but i have a fairly good idea of what's involved.

With tripples it would reach even more power.

Oh by the way i'm looking at building an identical motor to this with some help but not sure when. It mainly depends on me getting the money together.

[260freak]

yeah money its the greatest obsticle!!!

hell i'm still prepearing the body for rust removal and a paint job.....

good thing is i was able to pick up the block and head for free along with the whole car!

[Dan Baldwin]

The devil's in the details. *Some* motors like that make upwards of 300 crank hp. Others I've seen results for in the range of 165rwhp, or less. IOW, it DEPENDS!

Thing one, you'll have to shave the bejeezus off the P90 to get decent CR, or you could just use an N42. What kind of powerband are you looking to have? If it's a track car, you'll want a big cam and headwork to get big hp numbers. For a street car you can get killer torque and great performance with a milder cam and little or no headwork, but the absolute peak hp number won't be as impressive.

For a track motor, triple carbs are the bee's knees. You'll want 44 or 45mm, and headwork and a big cam are a must.

For a street motor you could use the stock SUs, or modified bored SUs, or 2" Jag SUs and you'll be doing fine.

Street motor, I'd aim for ~10.25:1 CR. Track motor, 11:1 (big cam allows for this).

Priorities should be:

maximize displacement

maximize compression ratio (dependent on cam)

maximize rpm (dependent on design usage)

[Gav240z]

Hi Dan i see your motor puts out an impressive 250rwhp can you tell us about the specifications of your motor?:classic:

[260freak]

did we even get the N42 head over here if we did how hard are they to find?

not sure exactly what the cars going to be used for most likely a lot of street use, hopefully a fair fem track days, i think you guys call it autocrossingand the dream would be a few amiture tarmack rallies.

so what sut up should i go for?

[Brett240]

260freak,

if you already have a p90 head stay with it and get it shaved till you have about 48cc combustion chambers, theres no need to use more money on another head if you dont have too.

with the bore size of the 3.1 you wont have a low compression, should be about 10.4:1, use L24 rods.

if you are running it on the street but also on the track crow australia make a stage 3 cam which is a good comprimise, and some porting, especially the exhaust - what dan said-

ive seen a motor built like this using fuel injection make over 200kw at the wheels (285 hp?) on a dyno and its awesome!

(it had an open exhaust however)

[Dan Baldwin]

200rwkW/.7457 = 268rwhp, not too shabby!

N42 heads came on 280Zs over here in the States. If they're not available in Oz, shaving the P90 sound like your best bet.

What setup *should* you go for? I'd say get the full 3.1 displacement (LD28 crank, L24 rods, 3mm overbore, KA pistons) and aim for 10.3:1 with a 2mm gasket. With KA24 pistons with only the raised rim shaved off (.5mm), that means you want ~43cc chambers.

side note: LEngine calculator gives incorrect CR for shaved dished pistons. For .5mm shaved KA pistons, put in 0 (zero) for "fly cut" in LEngine, then subtract 0.1 (more like .075 really) from the CR result.

I think you'll end up shaving a P90 more than .080" to get there, so shimming the cam towers will likely be required.

This setup will allow you to run stock cam on pump gas, but gives you the ability to go as high as 11.6:1 with a 1mm gasket. Or you can make a 1.5mm gasket by removing one of the .5mm layers from a 2mm gasket to get 11:1.

I'd start with a stock or mild cam and SUs, KILLER street setup. Should have you in the 205 rw lb-ft range, with peak power maybe ~195rwhp at maybe 5200rpm?

From there you can cam, carb, and headwork your way up as desired. FWIW, my setup is shite below ~3200rpm. Kick-arse at the track, though! Probably not too good for autocross.