Trying to figure the early drop-off in torque. 383 sbc, gen 1. 8.3 scr, Edelbrock Vic. Jr. heads and intake. Modded 750 dp'er Holley. Boost-referenced fuel system (A-1000). Cam is 242/248 solid roller on a 110* lsa. Running > 12 lbs. boost @ 6k rpm's. 34* advance all in by 2800 rpm. a/f ratio is around 11.5 'till shut-down. TIA.
http://i19.photobucket.com/albums/b156/big_G1/dynorun7.jpg

It could be a couple things.

First thought is belt slip on the procharger. That's generally what the graph looks like when the belt slips.

Another thought is valve float but the graph doesn't support that as well.

Do you have AFR recorded anywhere? If so that might give us another clue.

BTW: Have you considered the Edelbrock RPM Air Gap intake for this application? It will make the same HP as the Victor Jr. and improve the low end torque (as if you need more right? :lol:) a lot. And it doesn't hurt the top end but a couple HP compared to the Super Victor in an NA application. A blower makes the HP difference even less significant.

Check out the intake manifold article in Chevy Hi Performance this month. (http://www.chevyhiperformance.com/toc/thismonth/index.html) Good read!

It could be a couple things.

First thought is belt slip on the procharger. That's generally what the graph looks like when the belt slips.

Another thought is valve float but the graph doesn't support that as well.

Do you have AFR recorded anywhere? If so that might give us another clue.

BTW: Have you considered the Edelbrock RPM Air Gap intake for this application? It will make the same HP as the Victor Jr. and improve the low end torque (as if you need more right? :lol:) a lot. And it doesn't hurt the top end but a couple HP compared to the Super Victor in an NA application. A blower makes the HP difference even less significant.

Check out the intake manifold article in Chevy Hi Performance this month. (http://www.chevyhiperformance.com/toc/thismonth/index.html) Good read!

The 'charger has a 12 rib belt, and seems pretty tight. I need to log boost at my next dyno session. I am not sure about the timing...don't see or hear any detonation. The Vic Jr'. heads are set for a 1206 gasket, so the Vic. Jr. intake was a better match. Also, I've heard that dual plane intakes are a no-no on F/I...maybe fuel distribution problems? If I wasn't so cheap and lazy...egt sensors on all 8 would be cool. AFR is at 11.5 to 12.0 thru-out the run. The valves are set at 200 lbs on the seat. That should prevent valve float, especially under 6,500. Thanks, Gary.

Nice numbers, would like to see what final numbers are after tuning. :drool5:

One other thought since I don't have a pic of your engine compartment/ blower intlet to look at.

Could it be collapsing and getting sucked shut at the high end? If it's metal tubing - no way, something else.

One other thought since I don't have a pic of your engine compartment/ blower intlet to look at.

Could it be collapsing and getting sucked shut at the high end? If it's metal tubing - no way, something else.

Inlet is metal tubing. Just got my PLX 3-bar module yesterday and tonight I configured my LM-1. I will play this week-end.:party:
http://i19.photobucket.com/albums/b156/big_G1/PDRM0307.jpg?t=1217641763

Definitely NOT the blower inlet plumbing. Filter-Blower :lol:

Blower exit plumbing looks awesome too!
Wondering if there was a boost leak at one of the joints? That's about the only other thing that stands out as a possibility.

great numbers

I like the numbers!

It could be a couple things.

First thought is belt slip on the procharger. That's generally what the graph looks like when the belt slips.

Another thought is valve float but the graph doesn't support that as well.

Do you have AFR recorded anywhere? If so that might give us another clue.

BTW: Have you considered the Edelbrock RPM Air Gap intake for this application? It will make the same HP as the Victor Jr. and improve the low end torque (as if you need more right? :lol:) a lot. And it doesn't hurt the top end but a couple HP compared to the Super Victor in an NA application. A blower makes the HP difference even less significant.

Check out the intake manifold article in Chevy Hi Performance this month. (http://www.chevyhiperformance.com/toc/thismonth/index.html) Good read!

went to the site yup good!