rxse7en

Does anyone know if there were ANY cars that came stock with high-impedence, 720cc injectors, be it domestic or import and I don't mean RX7s. I guess they can only be bought new in the aftermarket? Would be nice to go to the junkyard and grab some on the cheap! But, with that being said, I just got myself wondering if there were any cars that came with them.

Thanks all,
Brian

Ryde _Or_Die

I don't think so. Rx7s have larger than normal injectors I've found. Like my friend is going to upgrade his 300zx TT to like 420s or something like that, maybe even smaller. I doubt theres any that are larger than FDs were(I am sure there are some stock at some point). And those aren't the same style I don't believe.

RX7withNitrous

y do other car's use such low injectors and rx7's use huge ones. My piston's don't understand when i start talking about 720s or 850's they are wanting to upgrade to like 550 and ****. Crazy piston stuff.

Ryde _Or_Die

First off, if you haven't noticed Rx7s aren't gas sippers. Secondly, V6s have 6 injectors(which is what a rotary is usually compared to).

6x350=2100
4x550=2200

Not so big of a difference now is there?

RX7withNitrous

it's usually the guys with the 4cyl turbo's though eclipse, mr2, wrx ( i think that might be a 6 cyl. )

Ryde _Or_Die

No your right, all those are 4 cylinders. But just remember the rotary compares to a v6, not a 4 cylinder.

V8kilr

what about graben some out of a 1st gen, those could be had cheap at the right junk yard.

and some of them flow some pretty nice rates.

Ryde _Or_Die

I bought a pair from someone on here from a gsl-se(680cc). Sent them to rc to be cleaned and one was totally fucked. Meant both had to be completely rebuilt($350+). So I just let them keep them and I bought some brand new 720s for $220.

RX7withNitrous

where did you get your 720's from? What's this about first gens? I have two first gens in my back yard rusting away.......they have 720's?

Ryde _Or_Die

I got mine from rx7store.net. Not all first gens have the big injectors. Just the 12A turbos from overseas and the GSL-SE's.

BlackRx7

you can run 720 low imp....you just gotta run resitors like me...my 720s run fine..though if your on the stock turbo/intercooler/ports I'd just get a walbro... I ran a 14.7 with my 720's and my safc set to -12% above 4K rpms, with the stock injectors I ran a 13.8...

sonic7

iTrader: (1)

does anyone know in what scenario someone would run 1500cc secondaries

RX7withNitrous

Well i think i have a gsl-se would i be able to just put those in my TII do they just plug right up.....I'm getting excited haha.

RX7withNitrous

wait wait what do third gens have..........

TonyTurboII

550s and 850s. Dont bother though, the 850s are side feed.

RX7withNitrous

awwwwwwwwww that would have worked out great.

TonyTurboII

Yeah, great for you, and great for the third gen guys who have to buy new fuel rails if they want bigger injectors.

Ryde _Or_Die

Well they are going to be low impedence from the GSL-SE. Check at mazdatrix to check your VIN to see when your car was built. I know my car has low impedence, but halfway through 87 they switched to high impedence.

West TX RX-7

I just got back from Marvelspeed in Rowlett to drop my car off and we visited about that specific subject.
It seems with larger primaries the car doesn't idle or run as smooth on everyday driving. So they (Don and his brother( both recommended staying with stock primaries (better idle and in town drivability) and going with 1600 secondaries. That is plenty of fuel when your on the gas. This is for running a 62-1 with a haltech and FMIC. His brother ran the same deal though on his 600 rwhp T66 setup. He said with the stock primaries it was perfectly streetable with those HP numbers and lag was not a concern.

They believe in efficiency though and he was only running 14psi to make that 600 rwhp. He said the motor was built to handle 25-30 psi but they never needed to turn it up because at 600 he couldn't keep the tires under the car.

RETed

Nothing runs stock top-feed 720cc, high-impedence fuel injectors.


-Ted

HeffBoost

Yes sir, on a LI anyway, +resistors for HI.

ForsakenRX7

At what point do you guys feel that the secondaries should go to 680s or 720s?

RETed

If you got the fomulas, you can do the math.
Stock 4x550's @ 85% pulsewidths can barely support 250bhp at the flywheel.&nbsp If you're shooting for more power, then you need bigger fuel injectors.


-Ted

ForsakenRX7

Good enough answer for me.

chuck8313BTSDS

Ted
How much hp will 4-680cc injectors at 100% pulsewidth produce? Stock turboII fuel pressure reg, Air temp in the low 60 deg and timing at 25 deg at 4000rpm and above, 19psi of boost. I dynoed the car at 416rwhp.

chuck