Dear_Riah

Hello everyone, asking around to see what size I should run on my '88?

Specs:
'88 rx7 13b half bridge port
NA
550 Haltech ECU with Haltech coil pack
MAF deleted
Stock upper intake
Racing beat headers and exhaust

Current debate, the ECU can handle any size injectors we throw into it, but what would be a good size for primary and secondary? The car is primarily a auto-x and short course track car. With stock upper intake I don't want to over flood the engine with high CCs injectors at the same time I don't want to limit my power.

750cc all the way around.
750cc primary. 1000cc secondary.
Other?

Thank you in advance.

Dear_Riah

Mazdarian

iTrader: (1)

In before '6 port half bridges suck, ditch that and get a real engine'.. we know, OP already has the bridges cut so he's probably wanting to stick with them

750 primaries and 1000 secondaries on a stock intake half bridge n/a is a bit much, heck even 750 all around might be too much. Going off of other builds around here we've yet to see 200hp reliably on a similar setup, and for those numbers your injector sizes provide a LOT of fuel.. I'd size your injectors down to 550 al around, running out of fuel isn't going to be your main concern unless you plan on boosting in the future. 6-port port geometry, stock intake size and shape, it's all pretty detrimental to high n/a horsepower.

An off-the-shelf RB header is a decent part, but because it's not a road car you could look into a long-primaries header instead (or chop the RB one up before the collector, lengthen the primaries and reweld the thing), those headers will net you more over a short header. There's tons of information on long primary rotary headers on here, along with measurements etc.

Do you plan on running the 5/6-port actuators? Keeping them operational might preserve some torque below 3k rpm.

Do you plan on bridging the aux ports?

Edit; Darn, welcome to the forums btw!