Blown408

iTrader: (4)

I need some help guys.. I am planning on a 408 with the F1 Procharger. My goal HP is 800 at the wheels. Which injector should I go with? I wanted to go with the RC 75# injectors to give me some room to grow, but I have people telling me that the 60s would flow just as much and would support my goal HP.

I have also been told that the 75# injectors would be very difficult to tune.

Can anyone give any information that can help me out?

Thanks in advance.

cablebandit

iTrader: (37)

mototron 60# is what i recommend. Ask or search posts by Mightymouse ...he has the 60s and is over 800rwhp.

stevieturbo

IF I recall reading correctly, MM was pushing something crazy like 90psi FP to make his power with 60's.
Isnt he using 96lb's now ?

nick y

iTrader: (1)

i am running 60 motrons in my 03 c5 vert w/ptk twins a4 347 and hp2 bar sd.
my datalogger is showing 19.5ms @ 60psi!!!!!!!!!! that over 100%. BTW thats at 14 to 15 psi.
i dont know what to do! i do have pressure ref reg but not using it, is mm using one or is he just set at 90 all the timei

Blown408

iTrader: (4)

So I should go with the 75# injectors? Anyone have anything good or bad to say about the RC injectors?

Full Throttle

A non-boost referenced system is going to have a hard time keeping up with the type of boost and power you guys are making. Seems to me that a return style sytem with a good regulator will help . The 60LB Mototron will easily support 800 flywheel HP and maybe a good bit more with a proper fuel system. A non bost reference system will effectivly reduce fuel pressure by the amount of boost so a 60LB system with 10PSI boost is like having 50 lb of fuel pressure
Mike

2001-WS6

Mike is correct that the proper way to use any injector in a FI application is with a boost referenced regulator. This will keep the Mototron 60s well fed and you'll be fine for your goal.

The 60s are the smoothest and easiest injectors out their to tune and will easily flow in the range of 75lbs with boost reference on a good tune with the boost reference regulator. They are used in offshore boat racing applications which put a whole lot more stress on them than we do a 1/4 mile at a time.

My TTi Race kit car hasn't been on the dyno yet but we've made spinning passes near the 141mph mark in a car that weighs in around 3,650lbs with the driver. We're not out of injector yet. That's the zip code that you are looking for with your goals.

Rick

Pro Stock John

iTrader: (34)

At 800rwhp you will be close to maxed out with the Mototrons, but it might take you a while to hit that rwhp number.

Blown408

iTrader: (4)

Has anyone had a chance to tune the RC 75# injectors? Are they harder to get tuned in?

Blown408

iTrader: (4)

And by the way, I will be running a boost referenced regulator. Still not sure which injector to use though. I am still wanting to lean towards the 75s to give me something to grow into.

MIGHTYMOUSE

iTrader: (59)

it was 846rwhp and was 83psi fuel to do it (60 base + 20 boost) on mototrons.. they were maybe 90% duty or so i dont remember.

http://www.mototron.com/prod_minifuel_long.htm

try this calculator use a .65 bsfc http://www.rceng.com/technical.htm#WORKSHEET

yes now i run 96's at a lower fuel psi and its in a safe 70% range....until the 88mm arrives

Blown408

iTrader: (4)

800 BHP This is crankshaft HP too. (I am shooting for RWHP)

8 injectors

.65 B.S.F.C.

.80 Duty cycle

60 PSIG (Weldon 600 pump)

69.18 LB/HR 727cc/min


So by this calculation, I will need the 75# injectors right? Is there anything I am overlooking.

Thanks!

Full Throttle

The mototron units are rated 60lb/hr at 43.5 psi. Most go about 63 on the flow bench at that pressure. Given that you will likely run them at higher pressure (58?) and that they are completely stable up to about 93% duty cycle (we usually cap them at 90%) I see no reason why they will not work fine. RWHP is not a "percent" of flywheel, the loss does not change much as power goes up. If the driveline uses up 100HP at 400 hp it sure will not use up 200 at 800, more like 110. Those 75's are much more money and very tough to tune, they do not respond well to higher pressure. (75+) If you really want a bigger injector they consider the Siemens 72 lb/hr units and a driver box.
Mike

Full Throttle

http://motownmuscle.com/forums/showthread.php?t=16042

BLOWN408
maybe this will help you I just ran across it
Mike

gametech

iTrader: (1)

I like the mototron 60's. They were very easy to tune. However, with regards to the previous statement, if you do the math rwhp IS most definitely a percentage of flywheel hp.

Full Throttle

but it is not a constant percentage. it may be 20% at one level and it may be 15% at another. The drivetrain loss does not go up with horsepower. A given trans and rear end have about the same loss regardless of input power. Other that small changes in gear and bearing load the loss does not change much.
Mike

gametech

iTrader: (1)

I hate to keep off topic on this thread, but the way rwhp is measured is generally by accelerating the drums on the chassis dyno. Faster acceleration equals more torque equals more hp. Most of the drivetrain loss seen with this measurement is due to the rotational inertia of driveline components. While frictional losses may vary some, the inertial loss of accelerating all of those rotating parts is a fixed percentage of flywheel hp. If I can find one of my old college physics books, I will post up the actual equation involved.

Blown408

iTrader: (4)

Thanks for the link Mike, but I refuse to buy used parts like this. You never know what kind of person you are dealing with.

So far, everything (formulas) is still pointing to the 75# injectors.

DeltaT

iTrader: (5)

I just got my RC 75# (high impedance) injectors and they have been easy to tune so far. Idle, for some reason, is smoother than it's ever been to date.
Serious tuning session tomorrow.

Jim

Blown408

iTrader: (4)

Thanks for posting.. I ended up getting the 75's after all. I guess I will see.