I keep looking at that second dyno sheet, and when you compare the original dyno sheet of 486-TQ, the second one of only 336-TQ will have a direct impact on where horsepower will peak. If his torque is where it should be at the rear wheels, a tad over 400, I think this would help to peak his horsepower much higher than 4700-RPM (I say 4700 because 73Duster said he let off at 5000-RPM, and Bob told him his RPM gauge in the cluster was about 300-RPM too high). Even if Bob was shooting for 128 BLM's, he might have been very conservative with the timing, and that might be the difference why his numbers are so far off from the original dyno. We really need to see that Precision dyno sheet to be sure. 73Duster, can you post it up....?

I can't make it this week. I'm getting my seats reupholstered. All i have is this sheet. I also know from previous experience that you don't need a lot of cam to make decent power. This combo also shows similar numbers on desktop dyno. I know it's only a simulator, but they are pretty accurate. I'll try to make it to the track soon.

I'm almost convinced now that it's a timing issue, as it sounds way too conservative. That engine makes very good peak numbers, but it's the average numbers that are impressing me even more. I'm still in shock at how the horsepower number peaks at only 4600, but hey, big cubes, small cam, no rev. Now, I would reach out to Bob and ask if he has any datalogs saved (which I'm sure he does, he saves everyone's for future reference). What did he say when you told him the differences in numbers....?

thats a good truck motor!

.... are you sure you can't make it this weekend?

http://www.youtube.com/watch?v=j-3UAv9sgxk

Unless you were there for the initial dyno session I would not believe the numbers at all. They are alot of dyno tricks to give someone a dyno sheet that says this or that. I would believe the chassis guys dyno numbers as he is providing a service and not selling anything. A redyno of a big name crate engine is a humbling experience also. Most crates have vacuum pumps, jacked up brake specifics, and out of the ordinary A/F ratios to get the peak numbers. My engine was a big name motor and it was off by 70hp and 50 ftlbs on the redyno I did when I got it. I didn't care as I couldn't build it for what I bought it for. I have seen Shafiroff and Musi engines dynoed, all were 7-10% off of the dyno sheets sent.

I can't make it this weekend, next weekend maybe? I'd really like to meet you guys when i go. You sound like you know a lot more than i do. As for the car, it's in the upholstery shop and i won't get it back till next week. The car runs pretty good as far as seat of the pants. The only issue i have is the idle sometimes stays high around 1600 rpm or so. It goes down to about 1000 if i stab the throttle lightly. It does'nt always behave that way and it's got me stumped. I've checked the tps sensor and reset the iac and it still does it. Anyway, If next week is good i'll hit the track then.

Yeah, bring it on over when you get the chance, as I'll scan it to see why she's idling so high, as the scanner will tell me what the ECM is commanding as far as RPM, as well as what is fighting it. Could be something as simple as your coolant temp sensor, as this works in conjunction with your IAC, and if it's flawed, the ECM will think the engine is ice cold at all times, thus keeping your idle high even when warmed up. As for the engine making that much less than advertised, that 383 should be making at least one FWHP per every cubic inch displacement, and it's definitely way off (my old 350 w/moderate cam made just as much as that). That cam may be small, but it's no slouch down low. I still say it's the timing though....

Thanks for the input. Maybe we can meet next weekend at the track or wherever. I'm new to chevy and fuel injection in general and could use all the help i can get. If the following saturday( oct. 24) is good for you, I'm off that day. I don't know if the track will be open or not, but i'm open. Thanks.

I'll have to quote Gomer from LS1 Tech on this ocassion... "Dynos and A4's go together like turds and hot dog buns."

My 91' on a dynojet 248c only made 202 RW, it went 13.9 @ full weight. My 2000 when it was just bolt ons went 12.20 @ 112 MPH on a Friday night. Saturday morning I took it to Next Level and it only did 329 RW. I highly doubt you'll run 13.9-14.1 unless you blow the tires off.

Don't lose anymore sleep over it, get it to the track and make some passes. You need a solid baseline to work from. Try to keep a log book with tire pressure, launch RPM, how you stage, calculate the Density Altitude, etc. It will help you validate any changes and help you dial in the car.