articfriends

iTrader: (1)

Had to, when this manifold was on540 on dyno last summer i tried to run this TPIS 68 mm TB, it did all kinds of strange stuff ( broke up, lean popped with afrs in 12s), so we matched plenum correctly to it and it works well now

articfriends

iTrader: (1)

Going to finish dyno testing today, pumped the sunoco 93 out thats making 10 less hp, tested alchohol content, negligible. Doing same day, same dyno baseline on shell 89, will see if hp comes back up 10hp, doing timing test w dui module vs mercruiser, found way to test 500 efi FA, then fill in 80/90 map fuel tables call it done. Will post results, Smitty

BenPerfected

How far up have you advanced your timing on the dyno? We can run 38-40 with 9 to 1 CR on pump gas without detonation. Could be another 10+ HP

articfriends

iTrader: (1)

This was a budget build using factory iron heads, and flat top srp's that give about 8.7-1 compression, made its best hp on 89 octane at 36 degree total, at 38 on 89 had KR, at 36 and 38 made less hp even on 93 octane, I really expected to get higher numbers with more timing and octane and was really surprised with such low compression there was KR on 89 at only 36 total.

SB

iTrader: (1)

Domes on BBC's typically need more advance, especially with factory heads. Bigger domes, more advance. My experience.

BTW: 1, assuming fuel used is what engine needs and #2, more old school domes. That's why past 10yrs a lot of power had=sbeen made with better (high compression)dome design and head comb chamber design.

articfriends

iTrader: (1)

Funny thing too talking about detonation vs octane after wasting hours today pissing around with this when I really didnt intend to!!
Emptied out the lower power yielding sunoco 93 this morn, bought 10 gallons of the shell 89 that I have done the majority of my testing with, refilled fuel cell. Earlier in this thread I mentioned losing 20+ hp using a DUI module in the TBI distributer vs the stock mercruiser. So I set timing tables to 30 degrees from 3800 up, 40 to 100 map. Ran motor up to 4000, used a setback timing light, saw 29 degrees on balancer. Installed dui module AGAIN, repeated test, 26 degrees at 4000 up, The DUI module evidently does something different and yields less timing.Added 3 degrees timing thruout all of the timing tables to make up for it, made a pull, hp down to 525 and saw 3-4 dgrees of KR. came to conclusion that I was wasting time with it since timing must be coming back in at some point all though the KR was from tq peak up. Put tune from last week in with normal timing curve, re-installed mercruiser module, made pull, 3-4 degrees of KR, WTF? Put gun on it with set back, was only at 35-36 where timing table is set at during a loaded pull and kits been set at for last 40 pulls!. went back to shell, bought 5 gallons of 87 and 5 gallons of 93, drained out the 89, put in the 87 and pulled, 3-4 dgrees of KR, go figure. Drained fuel, put in the 93, no KR. Tells me their pumps putting out 87 today even when your buying 89! (how many people have blown thier stuff up on mid grade or premium, did they really get what they paid for?). I really want a octane tester but used ones are 4000$ plus! Never got to the HP 500 FA test!

Trash

I think I know the answer to this but have you done any testing on the Merc small blocks with the equivalent intake and throttle body from the same year?

SB

iTrader: (1)

Smitty, what I have found around here, is no one uses 89 octane in their vehicles. When it is boat season (June thru August) more 89 does get pumped.

On top of that, Premium only gets pumped more when it's Harley season and Snowmobile season. Bikes and Sleds don't take a lot of fuel....so I know the Prmium takes a while to get to a level where he station re-fills it. Add a winter like this, no sledding, no Premium being pumped.

If you watch the pumps with cars, you'll see everyone goes for the 87. This trend started when 87 octane gas went over $4.00 a gallon. I would see people with cars that required 91+ and the owner of the vehicle reached right for the 87.

We had a winter where lots of sleds burnt down using the Premium, and I traced it to two gas station, with a high percentage from 1 station. This was during the $4.00 + gallon years. I think Premium was like $4.60 or something like that.

So, maybe your 89 is old ? And/or maybe the 'winter blend' is adding issues ?

Just throwing stuff out there.

Panther

I detonated a brand new engine back in 2010... Upon tear-down there was absolutely NOTHING wrong with the engine... Put it back together and ran it from 2010 to 2014 without any issue. I blamed it on getting bad fuel.

Panther

I wonder what it would have done with the 525EFI cam?