Horsepower Estimate

[fixitman]

My early 1974 260Z was recently run on a chassis dyno to tune the Mikuni 40PHH carbs.  The tuning is not complete.  But, so far, 139 bHP and 143 ft lbs have been measured at the rear wheels.  Based on the following drive train description, what are realistic performance expectations?

Thanks

Drive Train Description

Production date:              April 1974

Air box:                                K&N Lamborghini 3-carb filter in Jim Wolf Racing aluminum housing with Mikuni air horns

Alternator:                          60 amp

Camshaft:                           Racer Brown SS-54-110 – 236 degree duration at 0.025” lift with 0 lash, 110 degree lobe centers, and 0.480” lift net, and valve spring/retainer package

Carburetion:                      Mikuni triple side draft, 40PHH with 32mm chokes

Cylinder head:                      Decked 0.020”

        Bronze valve guides

                                                280Z intake valves, 0.173” dia.

                                                280Z exhaust valves

                                                Valves and seats grinded

                                                Built by Floyd Link, Torrance, CA

 Exhaust:                               Custom fabricated with flanged connections

Header:                Euro Car Anti-Reversionary, 1 ½” dia. tubing, 3 into 2, 2 ¼” dia. collector outlet

System Dia.:       2 ¼”

Resonator:          Borla resonator

Muffler:               Borla turbo muffler

 

Fuel rail:                               Custom fabricated to duplicate functions of the original system using original brackets

Ignition:                               New stock coil

                                                New stock distributor

                                                Taylor 8mm Spiro-Pro

                                                NGK Iridium spark plugs

Oil pump:                            ZX-Turbo unit

Pistons:                               Datsun 0.040” over, flat top        

Differential:                        R180 limited slip, 3.545 R&P set, Bob Sharp Racing spare

Transmission:                    New 1978 280Z 5-speed

[gnosez]

Size of the air horns (length)?

Spark plug # (5-6-7) and gap

Head work (port & polish)?

CR?

Distributor?

Timing set at?

No MSD or similar box?

Picture of header (seems to be too small)

R180 LSD in a 3:54 diff? And coupled to an "A" tranny - big gap between 2nd & 3rd as opposed to a "B" ZX tranny and a higher ratio diff.

[fixitman]

These are all the answers I have at hand.  I would appreciate any suggestions. 

Thanks

 

Size of the air horns (length)?  Standard short horns, 25 mm

Spark plug # (5-6-7) and gap  NGK 6637 BPR6EIX / 0.036

Head work (port & polish)?  Yes

CR?  Don't know.

Distributor?  Stock

Timing set at?  Don't know.

No MSD or similar box?  None

Picture of header (seems to be too small)  Dimensions are as noted.  See attached photo.

R180 LSD in a 3:54 diff? And coupled to an "A" tranny - big gap between 2nd & 3rd as opposed to a "B" ZX tranny and a higher ratio diff.  Gearing is stock 280Z.

[Patcon]

I like the air cleaner and the fuel lines look good. You have quite a few lines running around the front of the valve cover. what are they? Sorry for thread jack...

FWI I spent some time looking at 0-60 calculators but couldn't find one that gave good results; need to be able to input more detail but couldn't find one like that...

[fixitman]

The lines are fuel supply, fuel return to gas tank, carbon canister vacuum and canister purge.  The lines can be tracked in this photo.

[gnosez]

That is one very nice engine and engine bay!!!

[Patcon]

1 hour ago, gnosez said:

That is one very nice engine and engine bay!!!

Yes, looks great!

[NVZEE]

Built by Floyd Link -- from BRE? Based on that, it should run as good as it looks! But for quickie comparison, there's at least one other 260 dyno thread around here:

 

 

[fixitman]

Thanks for the link.  Based on this dyno test, my tune seems pretty good.  Floyd Link rebuilt the head in 1983.  This project is finally coming to an end.

Edited February 3, 2016 by fixitman

[gnosez]

I would think that with some carb tuning, advancing the timing, and a better dizzy you should see another 10-20 hp. I base that on our L24 street/track engine with triple 44mm and a similar build as yours. We got 210@crank running 110 octane at 34 degrees advance with a CR of 12:1. The L28 and 3.2L engines in full race mode make 294 and 345@crank respectively. Those run between 13.1 to 13.7:1 CRs. We use a 75 dizzy (vintage rules), an MSD box, 8.5 Magnacor wires and NGK non-Iridium plugs (race fine wire instead).

Where may I ask did you get your R180 LSD? I would suggest a 3:70 or 3:90 ratio diff to improve the driving experience.

Edited February 3, 2016 by gnosez

[fixitman]

Is there a dizzy that you would recommend?

Thanks

[Kurbycar32]

Rebello recommended the 280zx dizzy with the matchbox IC.  He said he liked that unit more than the aftermarket distributors.  I installed one on my Rebello 3.0 and it made a massive difference over my worn out 260z electronic distributor.