BSFC & power

[Arthur]

I received a pair of Cleveland iron heads & Holley Strip Dominator int. which is heavily modified for a look see. This is a vintage road race combination & he is asking for 600+ at say 7,500 ish. These boys will race from several hours to 7 hours the same day.

I asked the customer to send a dyno sheet. (SF902T).

Actual cu.in. is 351. 12:1 max. comp.

Intake ports were scratched all over but unchanged. The int. throats were bored straight down to 94% & 45 seats. No fill.

No finish work at all to the ST, just a straight sharp 90* edge full width.

Exhaust are brazed at the floor & pretty much follow the shape of the AMC 360-390. ST rolled to limit. 1-3/4 header, limited choice.

2.19 x 1.71 stainless. Common air flow peak @340 & upper 50% ratio exhaust.

Solid roller 262/272/106@102. - (a bit long winded.)

Dambest 950, w/BSFC of .844@ 4,000 - .822@ 4,500 - .708@ 5,000 - .628@ 5,500 - .595@ 6,000

.567@ 6,500 - .570@ 7,000 - .564@ 7,500 - .559@ 8,000 (Not a popular carburetor))

4,000 = 271-355
4,500 = 302-351
5,000 = 372-389
5,500 = 443-423
6,000 = 484-423
6,500 = 516-417
7,000 = 541-405
7,500 = 555-388
8,000 = 557-364

Intake had been extremely widened at the center divider with welded exterior from breakthrough. The spread bore flange had been cut off & a 4150 flange welded in it's place. This reduced plenum volume significantly.



Not to good results but, my question is, I don't have a clue about is how the rich fuel curve hurt's the average HP in this case vs. Is a BSFC formula available to say, moving from .650 to .450.

Looks like a few liberties have been exercised -
Carb has a serial # - easy to check original specs
Nothing to fear but fear itself

[John Haskell]

I would bet somewhere along the conversation with Robert Yates, the topic got changed to AFR from BSFC & I wasn't sharp enough to catch it.

So, it sounds like those little tid bits I picked up many years ago were the wrong thing to look at when scanning the sheet for exhaust side efficiency or anything else.

That's a good thing however I do not get into Dyno work at all. But I thought I could tell a little about what is going on with this gentlemen's engine however, there wasn't CFM, BSAC, vacuum, exhaust temp. It may be a small shop without the funding to complete it. (it is in Germany).

I look into this site when I wind down at night. It is a fun thing to do & outside of the but-heads it's a good learning tool. Just have to sort it out.

Can you boys lead me to a site that I can pick up on what discusses dyno operation techniques for some learning ?

[DaveMcLain]

I would bet somewhere along the conversation with Robert Yates, the topic got changed to AFR from BSFC & I wasn't sharp enough to catch it.

So, it sounds like those little tid bits I picked up many years ago were the wrong thing to look at when scanning the sheet for exhaust side efficiency or anything else.

That's a good thing however I do not get into Dyno work at all. But I thought I could tell a little about what is going on with this gentlemen's engine however, there wasn't CFM, BSAC, vacuum, exhaust temp. It may be a small shop without the funding to complete it. (it is in Germany).

I look into this site when I wind down at night. It is a fun thing to do & outside of the but-heads it's a good learning tool. Just have to sort it out.

Can you boys lead me to a site that I can pick up on what discusses dyno operation techniques for some learning ?

Try this link to the Land and Sea dyno website. They have a lot of good technical information which will help you learn how dyno testing works.

https://www.dynomitedynamometer.com/dyn ... h-talk.htm