Terrorist attack in cylinder 1
09-29-2012, 04:57 PM
#41
Boost Pope
iTrader: (8)
Join Date: Sep 2005
Location: Chicago. (The less-murder part.)
Posts: 33,050
Total Cats: 6,608
It's at the top, under "Spark".
FWIW, upload the whole MSQ file. There are other potential gotchas, such as spark table switching which could be at play.
Verifying the base timing rather thoroughly with a timing light is also absolutely necessary, in order to ensure that the timing in the table is actually what you're getting.
FWIW, upload the whole MSQ file. There are other potential gotchas, such as spark table switching which could be at play.
Verifying the base timing rather thoroughly with a timing light is also absolutely necessary, in order to ensure that the timing in the table is actually what you're getting.
Reply
0
0
10-04-2012, 03:33 PM
#42
Senior Member
iTrader: (1)
Join Date: Sep 2011
Location: Lambertville, NJ
Posts: 1,215
Total Cats: 74
https://www.miataturbo.net/meet-gree...15/#post873698
'99 with link piggyback. Conservative spark. No signs of severe det on the pistons I could find. All rods bent. And after the piston collided with the valves, I had bent valves too. The previous owner is a very good friend and a somewhat careful guy. He's never over-revved and neither did I. But we did run 14psi on stock rods.
Reply
0
0
10-05-2012, 09:47 AM
#44
Moderator
iTrader: (12)
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 20,664
Total Cats: 3,013
Bending rods can also be indicative of overly high cylinder pressures being caused by timing being too advanced. If the charge in the combustion chamber reaches too great a pressure as the piston is still rising toward top dead center the rods may bend under the load. There are situations where the fuel octane and other related parameters are adequate to prevent detonation at a particular cylinder pressure and spark timing but the cylinder pressure may still overcome the strength of the rods. Tuning to prevent detonation is important but should not be the only consideration.
Good luck.
Reply
1
1
10-07-2012, 03:21 PM
#47
Senior Member
Join Date: Apr 2011
Location: Martin, Slovakia
Posts: 507
Total Cats: 74
Bending rods can also be indicative of overly high cylinder pressures being caused by timing being too advanced. If the charge in the combustion chamber reaches too great a pressure as the piston is still rising toward top dead center the rods may bend under the load. There are situations where the fuel octane and other related parameters are adequate to prevent detonation at a particular cylinder pressure and spark timing but the cylinder pressure may still overcome the strength of the rods. Tuning to prevent detonation is important but should not be the only consideration.
I run 98 ron and now that the weather is cooler it is difficult to induce ping even with advanced timing. I will proceed with caution.
14psi on one turbo = 10psi on another turbo with regard to cylinder pressure so be careful with generalizations about psi. Intake manifold pressure is directly related to exhaust flow restrictions and is not a direct measure of cylinder inlet volume, but rather the flow limitations of the system.
I guess the hot side on a smaller turbo would create more exhaust back pressure and therefore limit power if the turbo/wastegate is the bottleneck in the exhaust.
As for cold side, I imagined that a given air pressure and temperature downstream of the throttle for a given engine/exhaust would result in the same power irregardless of what was producing the air flow.
But are there some additional effects due to things like more turbulent air or shock waves going on that limit power when producing boost with a smaller turbo?
Any further insight would be appreciated.
Reply
0
0
10-07-2012, 03:35 PM
#48
Boost Pope
iTrader: (8)
Join Date: Sep 2005
Location: Chicago. (The less-murder part.)
Posts: 33,050
Total Cats: 6,608
The turbine-side is a big part of it, especially during the ramp-in where the wastegate is still fully closed.
A smaller / more restrictive turbine will cause back-pressure to be greater, specifically in the area just outside the exhaust valve in the head. The practical effect of this is that cylinder scavenging in the exhaust phase is less complete- more exhaust gas remains inside the cylinder at the end of the exhaust cycle. Thus, the amount of fresh air / fuel which is drawn into the cylinder during the intake cycle (by mass) is less for a given manifold pressure. Or, it takes more manifold pressure to force the same amount of air/fuel into the cylinder during the intake cycle.
A smaller / more restrictive turbine will cause back-pressure to be greater, specifically in the area just outside the exhaust valve in the head. The practical effect of this is that cylinder scavenging in the exhaust phase is less complete- more exhaust gas remains inside the cylinder at the end of the exhaust cycle. Thus, the amount of fresh air / fuel which is drawn into the cylinder during the intake cycle (by mass) is less for a given manifold pressure. Or, it takes more manifold pressure to force the same amount of air/fuel into the cylinder during the intake cycle.
Reply
1
1
10-07-2012, 03:44 PM
#49
Senior Member
Join Date: Apr 2011
Location: Martin, Slovakia
Posts: 507
Total Cats: 74
Joe, I'm intimidated by your knowledge as displayed in your reply to this and countless other posts scattered throughout the forum.
In short, you are far too clever to be posting here
In short, you are far too clever to be posting here
Reply
0
0
10-07-2012, 08:13 PM
#59
Junior Member
Thread Starter
iTrader: (1)
Join Date: Aug 2011
Location: Queens, NYC
Posts: 150
Total Cats: 6
Did that msq file work?
FRT, thanks but again, a friend of mine came up with that on the night of.
czubaka, sorry to hear about your unimpressive engine failure. Just do a burn out and im sure something will poke its head out. lol so whats next for you?
FRT, thanks but again, a friend of mine came up with that on the night of.
czubaka, sorry to hear about your unimpressive engine failure. Just do a burn out and im sure something will poke its head out. lol so whats next for you?
Reply
0
0
10-07-2012, 09:43 PM
#60
Haha! I wish, car won't start. Pulled the plugs today, #3 is smashed. Looking down in the hole showed a piston broke in half.
Plans depend on what's borked. Base plan is just to get a salvage motor and drop it in. If anything is still serviceable in the motor, I may put in stouter pistons/rods. With all the coolant in the oil pan, the block is probably toast. Now seeing the plug electrode smashed, that doesn't bode well for the head.
This would all be much easier to pay for if I had a job right now. :(
Plans depend on what's borked. Base plan is just to get a salvage motor and drop it in. If anything is still serviceable in the motor, I may put in stouter pistons/rods. With all the coolant in the oil pan, the block is probably toast. Now seeing the plug electrode smashed, that doesn't bode well for the head.
This would all be much easier to pay for if I had a job right now. :(
Reply
0
0
