helicoil

iTrader: (104)

Just looking for a rough 'guesstimate' on where I will end up on boost with a 7.250" crank pulley and a 4.25" supercharger pulley.

Combo is a 403 with AFR 205 heads and a 1 7/8" tube header pushiong through a catted Y and 3" single pipe to a Magnaflow exhaust. EPP blower cam and FMIC.

I sent my tensioner to SDCE for the spring tensioner mod and have to change to 'their' largest pulley combo which I mentioned above. I initially was going to run the ATI set-up at 7.625" and a 4.75". I wanted to be around 10-12lbs, and might have been close, but now I think I will be higher. Has anyone ran this combo?

Engine speeds around 6200-6500 RPM.

Thanks!

speedracer5532

iTrader: (8)

I am running the 7.625 and 4.75 setup which puts me at 14 lbs at 6700 rpms. What injectors are you planning on running? If you truly don't want to make anymore than 10-12 lbs of boost the 60 lb motrotons will work. I am at 120% duty cycle at 6700 rpms with 60 lb injectors. I am probably going to have to look into some low impedance injectors.

helicoil

iTrader: (104)

The SDCE set-up puts the drive ratio at another 10% over from the 7.625" and 4.75" pulley combo. Can you tell I am an old roots guy?

70% over on the 7.25"/4.25"
60% over on the 7.625"/4.75"

If I run 6200 RPM X 7.250" / 4.25 X 5.4 = 57,112 head unit RPM
or 6200 RPM X 7.625" / 4.75 X 5.4 = 53,744 head unit RPM

doesn't seem to put the F1A in its sweet spot

However, it looks like it will be more than 14lbs, maybe 16lbs? provided all else is equal.

What do you run for an exhaust system? and camshaft?

Yes, I do have the 60#'s, how much power is yours making to eat all that up and what fuel psi is it running at with a 120% duty cycle.

Thanks for the info.

Gold Phoenix

iTrader: (1)

I was told by SDCE that with the same pulley set on my 402/F1R combo I would see 20psi at 6000rpm. But I haven't got it in the car yet.

speedracer5532

iTrader: (8)

I am running Kooks 1 7/8 headers and 3 inch true duals over the axle. I am running a custom cam 23x/24x 113+x.

I haven't dynoed my car yet. I am running the Racetronix dual intank fuel pumps with #8 line to a y block to the fuel rails and Aeromotive boosted reference fuel pressure regulator. My fuel pressure at 120% duty cycle is 72 psi. I have thought about turning my fuel pressure up alittle more. If I limit my rpms to 6500 my a/f is good but at 6700 it has leaned out to about 12.3.

kp

iTrader: (34)

You wont know until you try, I seen 20 psi with a 7.25/4.0 @ 7000rpm with the F1A and a 346. I think you will be fairly close to where you want to be at that low engine rpm.

helicoil

iTrader: (104)

Thanks for the info. Let me know your numbers when you get them. It must be making pretty good power.

helicoil

iTrader: (104)

Thanks. 15-17 is a touch higher than where I wanted to be but I am sure I will be able to get use to it. Boost is addicting! I learned that years ago. I could probably use better exhaust, but not wanting a real loud set-up as of now.

Really wanting to keep this a driveable street car with all the amentities of a stock car. Already have the race car thing covered.