Midrange and low RPM grunt. Discuss please.
#41
Thread Starter
Registered

Joined: Jul 2004
Posts: 11,332
Likes: 73
From: chicago
An oso member "BCK" emailed me his dyno sheet to post up this morning.
A 540CI, Bob M camshaft, AFR 315 heads, Victor JR single plane intake, and my guess is a very mild camshaft, per request by BCK. He said he didnt want to spin more than about 5400RPM. The air fuel ratio looks a bit lean, not sure if thats an accurate reading, but if so, I would expect the power to have been a little higher with a little more fuel. Maybe BCK will chime in on what took place during the tuning on the dyno.
Either way, 660HP, from a very mildly cammed 540, at only 5600RPM, is excellent IMO. Throw some cam in that thing, and 6000RPM, and he probably would easily have exceeded the 700 mark. But that wasnt his goal. Also, IMO, this engine package wasnt leaving anything on the table as far as low rpm torque was concerned, with the rect port heads, single plane intake.
A 540CI, Bob M camshaft, AFR 315 heads, Victor JR single plane intake, and my guess is a very mild camshaft, per request by BCK. He said he didnt want to spin more than about 5400RPM. The air fuel ratio looks a bit lean, not sure if thats an accurate reading, but if so, I would expect the power to have been a little higher with a little more fuel. Maybe BCK will chime in on what took place during the tuning on the dyno.
Either way, 660HP, from a very mildly cammed 540, at only 5600RPM, is excellent IMO. Throw some cam in that thing, and 6000RPM, and he probably would easily have exceeded the 700 mark. But that wasnt his goal. Also, IMO, this engine package wasnt leaving anything on the table as far as low rpm torque was concerned, with the rect port heads, single plane intake.
Last edited by MILD THUNDER; 11-09-2014 at 12:17 PM.
#44
Maybe Bob M will chime in again. I tied Bobs hands on that engine. I told him I wanted a long lasting, low maintenance engine, basically I was looking for stock reliability. I further told him that to avoid drive failures not to shoot for over 700 HP or 5400 RPM and you can see he delivered perfectly. Also Bob was leaning toward the Victor / Dom combination as being potentially a better combo with this engine but the actual builder was more comfortable with the Vic Jr / 4150 combo and I ended up going that route. It's a Pro Systems carb flowing about 1000 CFM with their modified metering blocks etc. The claim was that it had Dominator flow with 4150 driveability.
That pull is with the addition of a 2 inch spacer which helped a lot across the board. We tried open and 4 hole but it made no difference. Apparently it needed more plenum volume than the Vic jr had.
I'm not happy with that Dyno session/ operator. I've been told by someone else that saw the sheet that the AFR is dangerously low for a boat and shouldn't be run like that. Any thoughts?
That pull is with the addition of a 2 inch spacer which helped a lot across the board. We tried open and 4 hole but it made no difference. Apparently it needed more plenum volume than the Vic jr had.
I'm not happy with that Dyno session/ operator. I've been told by someone else that saw the sheet that the AFR is dangerously low for a boat and shouldn't be run like that. Any thoughts?
__________________
Straight bottoms and flat decks
Straight bottoms and flat decks
Last edited by bck; 11-09-2014 at 02:09 PM.
#45
Registered

Joined: Nov 2008
Posts: 595
Likes: 97
From: Hudson, IL
That's not exactly true. I have quite a few 700-800 HP naturally aspirated motors out with 4150 series carbs. More often then not people over carb a motor hurting low RPM performance.
#46
Registered
Joined: Aug 2011
Posts: 2,733
Likes: 8
From: bel air, md
#47
Registered
Joined: Aug 2011
Posts: 2,733
Likes: 8
From: bel air, md
I agree 850 with a 4150 is no problem but you are going to sacrifice some up top to gain down low with the smaller carb. Depends how your gonna run it. That's how I would size a carb.
#48
I didnt say it cannot be done, it is more an issue then not normally thats all, plenty of guys run them with no issues, also plenty of guys ditch them and run 4150 style when you really dont need the dominators...
#49
An oso member "BCK" emailed me his dyno sheet to post up this morning.
A 540CI, Bob M camshaft, AFR 315 heads, Victor JR single plane intake, and my guess is a very mild camshaft, per request by BCK. He said he didnt want to spin more than about 5400RPM. The air fuel ratio looks a bit lean, not sure if thats an accurate reading, but if so, I would expect the power to have been a little higher with a little more fuel. Maybe BCK will chime in on what took place during the tuning on the dyno.
Either way, 660HP, from a very mildly cammed 540, at only 5600RPM, is excellent IMO. Throw some cam in that thing, and 6000RPM, and he probably would easily have exceeded the 700 mark. But that wasnt his goal. Also, IMO, this engine package wasnt leaving anything on the table as far as low rpm torque was concerned, with the rect port heads, single plane intake.
A 540CI, Bob M camshaft, AFR 315 heads, Victor JR single plane intake, and my guess is a very mild camshaft, per request by BCK. He said he didnt want to spin more than about 5400RPM. The air fuel ratio looks a bit lean, not sure if thats an accurate reading, but if so, I would expect the power to have been a little higher with a little more fuel. Maybe BCK will chime in on what took place during the tuning on the dyno.
Either way, 660HP, from a very mildly cammed 540, at only 5600RPM, is excellent IMO. Throw some cam in that thing, and 6000RPM, and he probably would easily have exceeded the 700 mark. But that wasnt his goal. Also, IMO, this engine package wasnt leaving anything on the table as far as low rpm torque was concerned, with the rect port heads, single plane intake.
[ATTACH=CONFIG]532351[/ATTACH][ATTACH=CONFIG]532352[/ATTACH]
#50
Registered
Joined: Aug 2011
Posts: 2,733
Likes: 8
From: bel air, md



