What's up H-T. I have a b20 vtec and I'm using rdx 410's on e85. At one point I was at 58 base fuel pressure and on low cam I was at 89% duty cycle at WOT. High cam was more than 100% at 6-6200 rpms. Anyone else having these issues? What's the max hp made using these injectors on n/a setups?

Oh and sorry for the misspelling of the thread title, I couldn't change it afterwards.

 

Funny but I was asked this sort of question by Rocket thru the week about a H22a we are playing around with and about to convert it to E85 and put some cams in it.

 

E85 uses a lot more fuel than regular pump gas, I went with id 1000 for my high compression 84.5x87 build, simply because it will allow me to run them at a lower max duty cycle, and cover any upgrades down the road if I decide to change something.

 

Are you using 410's as well?

 

Yes sir, you're correct about that. But I figured they'd be enough. But they're good though no doubt about it.

 

Anyone else maxed these out on their n/a setups and or with e85? I also wonder what's max hp with these on n/a motors.

 

Yeah we have RDX with 42psi at the moment,with STD cams and the power we are making on pump fuel its using 52% duty cycle.

 

Ah damn. You've got room while on pump gas . You plan on using e85 later?

 

Yes as soon as we make our mind up on what cams to use,we will also be using 70psi fuel pressure with a new Aeromotive fuel pump (currently a 255 Walbro)and I have a set of Grams 550cc injectors coming just incase the RDX arent upto the job.

 

Play around with the fuel injector calculator on deatshwerks website or contact them directly, FIC will be more than happy to help out as well if you give them a call, they all were a huge help when deciding how big of an injector to go with on my build

 

I changed my rdx for 1600cc's when i went to methanol fuel 240whp

 

Up the pressure! Those injectors like high pressure. I would say 70psi should give you enough flow.

 

Yea that's what i've been hearing. I already ordered bigger ones but I wanted to stay with the rdxes since they're OEM. I may save them for something else and just get bigger fuel pump.

 

Thanks mangggg! I've already ordered some from FID(fuel injector development).

 

What dead timing are you guys using at 70 psi for the rdx injectors?

 

At 45 PSI fuel pressure my RDX injectors are at 84% Duty Cycle at 9000 Rpm. This is on VP race fuel (gas based) and 225 Whp. This is an every day motor though. You can always turn up the fuel pressure, you might gain a little power by doing this as well.

 

Damm that's nice considering you're on higher octane than me. Are you using a aftermarket fuel pump?

 

Somewhere in the neighborhood of 220-240 on pump gas, much less on E85.

 

Ah ok. I've heard of like 240-250 on 93 octane.

 

The RDX injectors are a 410CC, at higher pressure they flow more. I have found that 50-60 psi base pressure will yield the best results, and should flow closer to 500cc, I think NA wise, they'll be fine for a 240-260whp setup. I'm currently using these injectors on my Race car, W/ a big shot of nitrous.

 

Nice. Hey how aren't you maxed out on nitrous? What size fuel pump are you using? Also what dead timing are you using by the way?

 

Im using the recommend battery offsets for the injectors.
my setup currently is wet, last shot was a 100, pills for a 175 are in, I have not yet made a track pass with that pill combo yet.
im on a walbro 255hp, I do plan to upgrade because this pump is rather old.. but its done fine for what I needed it to..

 

Not trying to thread jack, Just curious because my B20 build I'm doing will also be using the RDX's and walbro 255, what is the fuel pressure w/ the stock FPR on that setup? the 50-60psi base you mentioned? Or should I look into an adjustable FPR like the OP did?

 

stock fp is normally 40-42psi base pressure. Thats fine for older injectors, these newer styles require more base pressure.. because thats what they are built around. I'd get a aeromotive FPR, its what i've ran for years now, had AEM, had blox and had other off brands, which have all caused me issues... Aero has not.

 

Thanks. Added to my parts list