drozd_ws6

iTrader: (19)

Like the title says just got my car going finally and It is a 408 from Hpe with there stage 2 heads 244/248 cam on a 115 Fast intake with 90mm tb. Kooks 1 7/8 headers and Ati f1 blower. I got my sdce tensioner in the other day and installed it . Along with a 4.25 in blower pulley and has twin ati i/c setup. It has a rough tune right know so I haven't got on it too much took it to 5000 rpm earlier and only saw 3 lbs.of boost? I'm taking it to b tuned next week. But the boost i'm aiming for is 12-14. I'm lost

mdhmi

iTrader: (1)

Sounds like you have a boost leak. Only 3 #'s of boost at 5000 RPM ... Something is defintiely not right. That isn't a pulley problem..

Mark

SuperSport2000

Yeah you need to check your BOV. Are you running the stock ATI unit (I hope NOt). I run a 408 with a .244duration .620lift cam and with a 3.9" blower pulley (ati f1) and I make 11psi@5500 rpms. I also have a 8 rib SDCE setup. I would also check your preload setting on the belt setup. You should be around 20ft/pd of preload (if memory serves correct.) Also what filter setup are you running on the inlet of the blower? Lastly those stock Ati twin intercoolers are going to restrict a lot of boost so you are going to have to spin that F1 pretty good in order to make 12-14 pounds of boost.

drozd_ws6

iTrader: (19)

Thanks for all your help!! I am still running the stock bypass. My ATI race ready should be here next week! Whould it hurt to take the bypass off and drive it around a bit to see if that is the problem? I have my preload set at 15 is that not enough? I'm also running the regular ati inlet hat and filter.

SuperSport2000

15ft pounds should be good on the preload. I would just wait until you get the Ati unit and then goo from there. Did you already buy the new Ati rave bov? If not mine is up for sale. Also you will want to get a bigger filter on your inlet hat. You'll see about and extra pound of boost if you do that.
-Jasen

drozd_ws6

iTrader: (19)

yeah alreday ordered the bypass valve. do you have the part # for the filter

Bryan Wilkinson

iTrader: (1)

What size is your crank pulley. 4.25 is awefully big, boost would be down with a pulley that large. I run a 7 7/8" crank pulley and a 3.83 blower pulley on a F1-R, but I was running the same combo on a F1 and saw 16psi with the filter off. My cam is a little less agressive then yours but with that LS it should not matter. The split on your duration is a little shorter that what the blower would like to see, The other posibility is that your SDCE tensioner is not aligned properly and you are spinning the belt.

The last think to check is your blowoff valve, if you do not have the vaccum line hooked up correctly, it will not close the valve and you will loose your boost.

SuperSport2000

do a search for "ATI bigh filter setup" and you will find a part number

drozd_ws6

iTrader: (19)

Crank pulley is 7.25. alignment looked pretty good. maybe I'll have to take a closer look.

drozd_ws6

iTrader: (19)

Seems like all is well now! I tweaked the bracket alignment a little and raised the tensioner tension to about 25. Now I"m seeing 12 lbs. of boost at 6300 rpm.

Thanks for all your help!

SuperSport2000

good to hear!!!! That seems like a lot of tension. Just to be safe why don't you give scott a call a SDCE.
-Jasen

BIGBOS

Thats a boat load of tension on that, I was making 15psi with my F1 SDCE setup......

7.25" and 3.4" blower pulley

Single FMIC, 236/242 cam, 370 9:1 motor.....

99.9percenter

iTrader: (2)

How many RPM BIGBOS?