User Login    
 + Register
  • Main navigation


Lost Password?

Register now!
Fast Search
Slow Search
Google Ad

[Datsun 1200 encyclopedia]

Ernie's Twin-Weber Downdraft

(Redirected from Datsa73)

Datsun 1200 encyclopedia | Recent changes | Edit this page | Page history | Switch to MediaWiki mode

Printable version | Disclaimers | Privacy policy
Categories: Featured Cars | Forced Induction

Ernie "datsa73", who lives in the Seattle area, has a nice Datsun 1200 2-dr sedan with a unique custom-built twin-Weber downdraft intake system.




Ernie says:

I have been wanting this car to go faster so I rebuilt the motor years ago. It wasn't fast enough so I put the dual Webers on it. It went faster but not fast enough. So I installed Nitrous. It went faster but not enough. You can see where this is going...I wanted it to still go faster so I supercharged it. Well, it's faster!!

8,000 RPM A15 engine:



  • 1973 Datsun 1200 2-door Sedan
  • Datsun A15 Engine
    • Oversized deep dished forged pistons
    • Balanced
    • Ported A15 head with dual heavy springs (for 8,000 RPM capability)
    • Delta Cam
    • Dual Weber Downdrafts,
    • 50hp Shot of Wet Nitrous Oxide
    • Weekend Warrior: street licensed, but only put 4000 miles on it in the last 8 years

Twin Downdraft Webers

Datsa73 welds up aluminum plate to make the manifolds using the original A14/A15 manifold.

  • 2027.jpg
    • 36/36 Webers
    • This engine runs very well, has a slight lope at idle, but runs smooth at lower rpms. The power comes on harder starting about 3,000 rpm

At the 1/8 mile drags, Evergreen Speedway in Monroe, WA USA:

  • 16222.jpg
    • 1/8th mile track @ 9 second (equivalent to a 15.7 second 1/4)
    • Nitrous oxide, approximately 35 HP boost
    • Stock Datsun 1200 rear axle (H145 differential) -- never broken
      Later upgraded to B210 rear axle assembly (H150 diff) with Lincoln-locker (welded spider gears)
    • Stock 4-speed
    • FIAT tachometer
    • Stock 1/4" fuel line
    • 278 duration camshaft

I run one NOS and one Fuel nozzle right into the intake between the two carbs.

I have only ran the car on an 1/8th mile track at 9 second... I am running a electric fuel pump that pushes 8-10 pounds of pressure which seems to work fine. The blower is a screw type and it does look like an eaton. Not sure if it really is. You can google them on ebay. They run about $450. It is clutch drive so I installed a switch on the dash.

It seems to run fine. I am still able to run my RPM's up to 8000 on full boost with NOS. The A15 motor is really holding out.


  • Weber 36/36 carburetors
    • Jetting: 120 on all bores

Ernie rebuilt the A15 "with only 6k miles on it" during the winter of 2008/2009 "about 10 years since it's last rebuild".

After taking it apart I found out that it really didn't need a rebuild. The head was worn out so I rebuilt that. No new parts on the lower end. I ended up putting all the bearings back in as well as my Total Seal Piston Rings. So really my block was only dunked and dingle balled. That was it. The hatch marks in the cylinders were still there from my original build. The machinest told me to just put the thing back together.


  • A15 going back in

A set of stock wheels and tires (pizza cutters) and I can leave 2 patches of tread for over 60 feet and that's without the Nitrous!

The unlocked H145 survived years. The locked H150 didn't have a chance:

  • 18424.jpg
    Broken axle shaft

Now Supercharged

March 2009. As if a 50-HP Nitrous system is not enough, Ernie has added a Mercedes CLK Kompressor (supercharger) to the A15. The blower is driven off a Ford 5.0 pulley bolted to the crank in front of the existing A15 pulley. With this power boost, Ernie upgraded to an H165 rear axle from Datsun 411.


I finally got this project done and it only took me a couple of weeks.

Discussion: Supercharged 1200

Super B110

  • th_DSC01436.jpg th_DSC01438.jpg



  • Mercedes SLK 2.3 Kompressor (twin-screw design)
  • locked (welded) H165 differential
  • Rear axle from Datsun 411
    • H165 diff
  • Homebuilt traction bars
  • Tires Rear: Yokohama A048 R ADVAN 205/60R13
  • Tires Front: Federal 185/60R13
  • 10 psi blow-through boost
  • No intercooler, no water injection
  • 50 HP Nitrous shot
  • Stock 1/4" fuel line, 5/16" fuel hoses
  • MSD StreetFire Ignition Box and MSD tachometer adapter
    • Weber 36/36 carburetors
      • Jetting: 140 on all bores (up from 120 pre-supercharged)

KA Power

Ernie converted to KA24DE DOHC power! Estimated 390 HP

Super Bee KA24DR Mod

Twin Cam (156hp stock from Nissan S14)

Ernie changed to Twin Carbs, Supercharger and Nitrous


S14 Front Sump oil pan

The motor sits low so the oil pan interferes with the cross member. New motor mounts have to be made.

KA24DE is an inch shorter than the Z24, and uses similar motor mounts. Ernie used modified engine mount brackets so it would fit the A12 crossmember horns. He shortened the S14 engine mount brackets 1".

See L/Z/KA/SR_Crossmember#A-series_Crossmember

Ernie notched the 1200 crossmember so the KA front sump oil pan would fit low-down

24865.jpg 24750.jpg 24749.jpg 24748.jpg 24747.jpg 24746.jpg

Photo Index

Datsa73's Photo Album

1232.jpg 2027.jpg 2030.jpg

16222.jpg 16223.jpg 16224.jpg 16225.jpg 16226.jpg 16227.jpg

17329.jpg 18024.jpg 18025.jpg 18026.jpg 18027.jpg 18028.jpg 18423.jpg 18424.jpg

19278.jpg 19279.jpg 19280.jpg 19281.jpg 19282.jpg 19283.jpg 19284.jpg 19285.jpg 19286.jpg

Retrieved from ""

This page has been accessed 27,389 times. This page was last modified 03:15, 5 May 2016. Content is available under Datsun 1200 Club.