looks like the compression ratio self-correction mechanism is functional.
looks like the compression ratio self-correction mechanism is functional.
1995 Chevrolet Monte Carlo LS 3100 + 4T60E
If he has the 75.5lb/hr injectors 16psi isn't nearly enough with that setup.
Yeah I saw that a long time ago... Supposed to be 80 lb/hr injectors matched set from Westers. He's have been way better off letting westers do the tune too! 80 lb injectors at 16 PSI should handle about 350 HP... problem is the engine is closer to 500 HP...
He's already confirmed the chip said 454 SS so I know it has way to much spark for hauling 12k... and it's always been 150 HP short on fuel.... with 7 plugs running lean and oil on rim and one showing signs of fly turds I think it's to late for a tune? Maybe after a quick rebuild and new pistons?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
What saves most BB guys who overbuild is the peanut port heads. Once those are gone it doesn't take much to get out of the range of a 2bbl TBI. You could play with a 4BBL Holley setup or dual Rochester units but imo 500 HP is looking for a marine or aftermarket intake with a properly sized set of port injectors. Even the L29 intake doesn't really work well at that power level. BTDT.
Last edited by 1project2many; 04-29-2013 at 08:37 AM.
Robert I like that, self control compression mechanisum ,ever one needs one of them.
Just have him get a compression and leakdown test done. If everything passes, crank the fuel pressure up to 26 psi or something and try again. I'd like to see what the IDC is at an idle with that amount of fuel pressure.
give it some time and that's exactly what it will do. at some point, it will either stop detonating(assuming advance doesn't keep getting bumped up) or form a rather large hole through the piston crown, assuming the pistons don't shatter from the detonation first.Originally Posted by ony
1995 Chevrolet Monte Carlo LS 3100 + 4T60E
Keith Black domed 10.5 to 1 compression pistons with the aluminum CCed heads is probably the only reason they are melting slowly and not shattering. That and the guy wanted a massive tow rig not a race car. The engine and cam is designed like an off shore race boat.
It hauls a lot but not very often, it's weekly purpose is hauling wood, farm work, etc...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
IDC is almost the same as it is with 10 lbs, or 12 lbs, or 200 lbs. Self correction has been cut to less than 1/2 of what it should be. Don't play games trying to stretch fuel pressure. It's not the same as having properly sized injectors.Just have him get a compression and leakdown test done. If everything passes, crank the fuel pressure up to 26 psi or something and try again. I'd like to see what the IDC is at an idle with that amount of fuel pressure.
Did I mean PW when I said that?
Isn't the idea to keep it greater than 1.0ms?
This truck needs big injectors (or 4)
Well I wish this bin was only a 454 SS Spark Advance table! Add another 4-6 degrees!
Please explain why anyone would run a spark advance table that is more aggressive then a LT1 engine in a Tow Rig?
The last one we found just caused constant knock retard, but half the knock retard was also removed.
But this truck came from factory with no knock sensor...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
You know, Mark, more timing equals more power. Always. What I want to know is how people can think this, yet when I say "then 100000 degrees must equal 100000 more hp" they don't get it.
Chevmasta, what I'm saying is that without adjusting the tune the ecm won't change the PW / IDC even if the injectors change because the tuner disables part of the self correction mechanism. The scantool reports everything is correct even though it's not.
The BLM in his chip was not raped! TowMaster chip has stock BLM/INT settings. That BLM Rape seems to be a third adjustment after data logs...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
My bad. I thought you said it was disabled.
I had the towmaster chip from him.
As discussed, it appeared to me that what was sent was a spark map from a 454SS BAMY bin. However, in certain areas there's 4-6* more timing and very little fuel added anywhere.
My truck had 140 BLM's with a maxxed out KC at 255 and then it would start back over. And that was just highway cruising.....I never went more than half throttle i'd say......I knew something was wrong.
I still have the chip, but I refuse to even datalog with it as I worry about my engine.
I did like his "tow" settings with how the trans shifted later in the RPM band.
Posting Permissions
Reply With Quote
Bookmarks