astroboy

iTrader: (18)

This will be my muse this winter but until it gets really cold out I am going to plan and accumulate items to achieve my goal. Car will be mainly used for autox but it's possible she'll see other events if she proves durable and reliable.

Currently have: stock 94 block, t3/t4e, tubular mani, 3" turboback exhaust, 11x16x2.75 intercooler, 38mm tial wastegate, ms1, rx7 550's, mbcv, stage 3 spec clutch, fidanza flywheel, 5 speed, 94 driveshaft, 94 open diff, 94 halfshafts.

Supporting mods: koyo 37mm rad, coolant reroute, twin slim fans, mazdaspeed mounts (diff and engine), ppf brace, and some other things that are escaping me.

Planning on getting: forged rods, 750cc injectors, cops, 6 speed, limited slip, honda intake manifold (or similar), boundary engineering oil pump gears, all the other things for a rebuild.

Contemplating: Forged pistons, 99-00 head, headwork (p&p), 99-00 head with headwork (p&p), 3.9 gears, cams, different tb (if I do a honda im I would also give a 60mm honda tb a shot).


So I should probably do the forged pistons but I will not be going over 300whp (if I get there) so I don't feel it is necessity. I was also thinking of my head options to try to achieve my desired power while keeping the pressure lower. Also thinking I may need a beefier fuel pump than the stock one.

Please give some input?! Thanks in advance!

greenday3437

iTrader: (2)

If you're tearing the motor apart and have the money to do so, you'd be a fool not to go with forged pistons.

Savington

iTrader: (31)

Do the forged slugs. No reason not to on a 300whp motor that might see track time. I'd have forged slugs over the BE gears at 300whp.

Do ID1000s over 750s, idle quality will be the same or better than your RC550s and it gives you a bit of headroom later on.

Stock pump is obviously inadequate, Walbro 255HP or Denso Supra/300ZX pump will do the trick. You can make the power through an OE fuel rail/FPR but idle quality is degraded with the 255/stockFPR combo and I'd prefer to see a big-bore rail in the car at that power level. Stock fuel lines are fine.

COPs, LSD, 6-speed all good. Do an OS Giken if your wallet can stomach it, it will make the car significantly faster at those power levels. I think a Giken would be worth a minimum of 1 second at every track I go to at my power level. 3.909 gears are perfect for 300whp.

Honda manifold, good. Best bang-for-the-buck mod out there today. Mine was worth ~30whp with absolutely no loss in the midrange. OE Honda TB will make the power, although I would like to play with a larger one to see if there are any gains to be had.

Use a VVT head, not a 99-00 head. There are significant area-under-curve gains to be had with a VVT head, and they are as cheap if not cheaper than 99-00 heads right now. Your ECU can't control it, so get one that can (AEM, Hydra, Adaptronic) or wait for the MS standalone control box to finally hit the market. I'd suggest switching ECUs, though - the AEM specifically is absurdly cheap for what you get, and it gives you things like real boost control, real RPM-filtering knock detection, higher-resolution fuel mapping, and sequential ignition.

Whatever head you end up with (99 or 01+), don't touch it. 300whp is very obtainable with stock cams and ports, there's no need to dump a bunch of money into the head reworking it. Make sure it's flat, throw a set of Viton valve seals in it, and be done with it. The only thing I would do to a head is a BP5A cam in a '99 head - everything else is too expensive for the benefits.

If you track it at 300whp, the 37mm Koyo radiator isn't going to cut it. Get one of mine.