S13 NA Update

Ive been pretty excited about this build lately, the S13 has always been that car that i favour, so much so that the last 2 years its barely moved. Im pretty happy with everything ive already done on the car but going NA means a few things must change, i have always loved Quad Throttles but never used them, i picked up a set of 52mm throttles and the cut up an old inlet manifold to join them together. Its all just tacked up for now but its getting there.

On the other side of the engine ill be building some long 1.75″ runners all merging into a nice 4 into 1 collector and then a 2.5″ pipe all the way to the rear.

I want this car to be clean and free of anything that isnt needed, i deemed PS to be not needed so i pulled apart the rack and investigated what i need to convert it to manual.

All that needs doing is drilling the internal piston to allow air travel from left to right, plugging all the holes, then giving everything a good grease and refitting everything back together.

Ive built a Jig to emulate the crossmember with a few important geometry changes. Ill be remaking the crossmember from tube and raising the LCA mount point 50mm, the rack will be moved 50mm further forward and 10mm up to combat bind with short knuckles, ive also built a jig to remake the caster arm with a few cool changes to it aswell.

In the long run i want to be able to remake everything that bolts to an S13 chassis out of tube.

Its going to be super clean, im excited to see what the engine bay turns out like.

  1. soooo cool! N/A is best!

  2. From memory the best header design is.. 21-22 inches to collector. collector tapering down to 2 1/4 inches then tapering back out to 3 inch exhaust..
    From the header back the exhaust should be as free flowing as possable..
    “experts” who say you need back preasure don’t know what they’re talking about..

    • Thanks mate, ive been reading heaps of NA stuff lately, thats similar to what ive heard, theres heaps of people that have heaps of different ideas, i have an engine dyno at my disposal so maybe i can slipfit everything and try different lengths?

    • 21-22 inches seems awefully short, even with short duration cams that will put peak torque at 8000+rpm, and 3″ is awefully big, that is big enough to support 220+rwkw, far too big
      . How big are the cams your running Nigel?
      I would suggest a well designed 4-2-1 header, sizing and length depending on the rest of your build, Obviously you’ll need to play around with it on the dyno to get it perfect. I can give you the recipe off mine and the formulas used to get it if you’re interested. Think you have my number, cheers, Warren

  3. Runner lengths is ultimately dependate on the rest of the engine.. But if you have an engine dyno then the ultimate would be to design a temporary set off pipes that you can play with the lengths.. I also found that they like a long runner intake.. I ended up going as long as I could befor I ran out of room..

  4. Loving the throttles… Thats going to sound AWESOME!

  5. wicked man… gonna be so good!

  6. Nigel, if I were you I would go with 3” exhaust. Generally speaking 2.5” is great for NA as long the engine is somewhat small and has some bolt on’s. If you’re going with high comp. pistons and ITB’s your SR will benefit from 3” exhaust, trust me.
    There’s a lot of info on Burn’s:

  7. I would love to see new front crossmember

  8. Nigel, once you have pulled the steering rack out of the housing, simply cut the disc off (carefully so you don’t nick the rack) instead of drilling holes in it, it will help reduce the effort of the rack. I’ve just done this on another TRW Nissan rack not too long ago.


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