540 bbc and efi?

[altereddoug]

I have two bbc 540 engines. Both are really close to the same builds. One has a longer rod and dart 355 heads. Other Has CFD heads cnc ported out to 355. Both have 2.35 intake valves and stock exh. Both make pretty much same hp and torque. On a chassis dyno they make 707 rwhp and around 560rwtq, not enough variance between the two to list. Both were on c112. Same compression. Just a little different style solid roller camshafts .765 intake/.748 exh and around 286 duration, both were really close to same cams. Both motors were run in the same car, same transmission, convertor, gear, 2 1/4" headers to 4 1/2" collector, holley efi and msd ign, and same intake edel. super victor efi intake with 80 # injectors and 2000 cfm throttle body

Car runs 5.86 @117 to 6.5 112 in the heat @ 3350 lbs with a powerglide, 5800 stall and 4,56 gear and 32" tire

It seems to me that both are leaving about 100 hp somewhere. Trying to figure out what is going on. Not sure if the intake is causing this, which was port matched to the dart 355 cnc heads. I see where other guys are getting 950 hp out of them and around 750ft tq. so that shows I am around 100 off.
Only same parts in engine swap was headers, convertor, which tried another one. no real change. and holley efi tuned by matt bell and mds 7 programmable set at zero, and crank trigger. Both motors seem to run good and no issues. both less than 300 passes.
I did hurt a roller lifter and swapped to a bigger cam. 804/765 with a 29X duration what the guy recommended and it slowed down and lost 60'.

Trying to decide which direction to go. Try a different intake, choke down the collector and or swap out camshaft again. Thanks for any advice

[prairiehotrodder]

what are the compression ratio's ? To me the hp numbers seem about right. I went through this struggle awhile ago of comparing my 540 BBC results on the track to dyno numbers on websites and magazines. Its depressing. Once those guys similar motors end up in cars they run the same speeds as you do.
Brian

[swampbuggy]

Tell us more about the intake and the EFI,(nozzle placement and how much air the intake part of the EFI is "supposed" to flow in CFM . Mark H.

[RevTheory]

Are the guys making more power running carbs?

[Newold1]

Missing to much data here.

Again what is compression ratio?

What piston type and ring package with tensions?

Are you using a vacuum pump?

What is the intake manifold and throttle body?

What are the actual camshaft timing events?

Where is the camshaft installed.

What is your high rpms?

Have you done any data logging on the ECM and and its fuel strategy and timing?

Did you have any ECM timing pull downs?

What temps and altitude are you running the car?

Can you post the chassis dyno printouts?

[Orr89rocz]

For one, 5800 stall and 32” slick or bias ply will not dyno very well at all and the fact you make 700 whp shows its making good power

However trap speed at that weight doesnt seem to be much over 775-800 hp which does seem abit low.

[altereddoug]

Intake is a edel super victor efi intake with a 4500 flange. Ported matched to heads by cfm performance. Holley 2000 cfm throttle body.

Wiseco K243AS pistons. 42.4 popup. 13.5 on the 119 cc head dart head with 2.35 int . Piston I believe was .020 below deck and a .040 cometic head gasket.
Total seal plasma rings

Cam was .765/.740 lift wit a 284/292@.050 duration on 108 cl

hurt roller lifter so went with a recommended howard cam:

.810/.765 int on 285/295 duration on a 108 cl int lobe sep 112
had to pull a lot of fuel out of efi fuel curve and add more timing to get it to perform on dyno like other cam

FYI: static cranking compression went from 220 on 4th stroke to 185 with new camshaft.

It shifts at 6900 and on datalog it shows shifting at 7100.
altitude is 748 and temps are from 65 to 100 degrees. Illinois weather

I will have to get dyno and datalog uploaded. tonight

Started running a vacuum pump and belive it picked up about .03. idle 6 inches, high rpm 14"
Timinng is fixed from 36, new cam wanted 42. never made a full pass cause of weather last october