What causes boost to fall off as RPM's rise? (BAD ASSES INSIDE PLEASE!)
01-24-2013, 09:54 AM
#42
since you added another 14gph nozzle(about another 95.2 lbs per hour injector)
you should be able to bump the timing up 2 or 3 degrees and get where you want. I think it may also be possible to bump the pressure of your water/meth pump for even more flow.
that would be easy, and cheap. add a splash of race gas to your pump gas to be even safer.
01-24-2013, 11:00 AM
#43
I am building a similar setup only mine's a 365" aluminum block, ported 317's, same springs, comp 285 off the shelf turbo cam, same turbo only with the race cover, stainless, and inconel valves, trying to get to 1000 crank hp on e85 or methanol with no i/c.
I am wondering how much power you are making? and if you should ditch the i/c, before you change anything else. I would think, that you are nearing the threshold of the compressor with that i/c. with that much meth, you shoud be safe, and your turbo will thank you for opening up the flow.
Ps, I may have missed it, but what is this in? Mines going thru a shorty glide, in my 245" 4link dragster.
I am wondering how much power you are making? and if you should ditch the i/c, before you change anything else. I would think, that you are nearing the threshold of the compressor with that i/c. with that much meth, you shoud be safe, and your turbo will thank you for opening up the flow.
Ps, I may have missed it, but what is this in? Mines going thru a shorty glide, in my 245" 4link dragster.
01-24-2013, 02:01 PM
#45
not that I know of, but i bet you it is not helping. what is your IAT?
since you added another 14gph nozzle(about another 95.2 lbs per hour injector)
you should be able to bump the timing up 2 or 3 degrees and get where you want. I think it may also be possible to bump the pressure of your water/meth pump for even more flow.
that would be easy, and cheap. add a splash of race gas to your pump gas to be even safer.
since you added another 14gph nozzle(about another 95.2 lbs per hour injector)
you should be able to bump the timing up 2 or 3 degrees and get where you want. I think it may also be possible to bump the pressure of your water/meth pump for even more flow.
that would be easy, and cheap. add a splash of race gas to your pump gas to be even safer.
I am building a similar setup only mine's a 365" aluminum block, ported 317's, same springs, comp 285 off the shelf turbo cam, same turbo only with the race cover, stainless, and inconel valves, trying to get to 1000 crank hp on e85 or methanol with no i/c.
I am wondering how much power you are making? and if you should ditch the i/c, before you change anything else. I would think, that you are nearing the threshold of the compressor with that i/c. with that much meth, you shoud be safe, and your turbo will thank you for opening up the flow.
Ps, I may have missed it, but what is this in? Mines going thru a shorty glide, in my 245" 4link dragster.
I am wondering how much power you are making? and if you should ditch the i/c, before you change anything else. I would think, that you are nearing the threshold of the compressor with that i/c. with that much meth, you shoud be safe, and your turbo will thank you for opening up the flow.
Ps, I may have missed it, but what is this in? Mines going thru a shorty glide, in my 245" 4link dragster.
Yup! Don't forget with AC!
01-24-2013, 04:32 PM
#48
I think the only way to do this would be to put another map sensor in before the i/c and make a pid for it. I plan to just add another mechanical boost gauge pre i/c and see the difference compared to my boost guage at the tb. I don't think these cheap ebay i/c's are as good as everyone claims.
01-24-2013, 05:55 PM
#50
9 Second Club
In the UK, that means less than £5 each.
Then get a few cheap nylon push fit fittings and hose, drill/tap them into the IC end tanks or plumbing, then you can easily hook everything up to test.
Place the two gauges side by side on your dash and go for a blast. Yes you could log via sensors, but it will cost more money unless you can source some cheap OEM map sensors that read a suitable pressure range.
As for the boost controller. Surely with CO2, the mechanical spring pressure becomes irrelevant to max/min boost ? SO whether it's a 5lb or 25lb spring, the CO2 should be able to blow it either way ?
ie, can it not blow the gate open for low boost and blow it shut for high boost ? Does it not operate via closed loop where it trys to maintain the target boost pressure ?
Or is it just a basic open loop setup ?
01-24-2013, 10:35 PM
#51
Just buy two cheap pressure gauges and hook them up. Anywhere that sells pneumatic equipment will have them very very cheaply, and in a variety of pressure ranges. I say buy both in 0-60psi, then you can use them to check boost pressure and EGBP
In the UK, that means less than £5 each.
Then get a few cheap nylon push fit fittings and hose, drill/tap them into the IC end tanks or plumbing, then you can easily hook everything up to test.
Place the two gauges side by side on your dash and go for a blast. Yes you could log via sensors, but it will cost more money unless you can source some cheap OEM map sensors that read a suitable pressure range.
As for the boost controller. Surely with CO2, the mechanical spring pressure becomes irrelevant to max/min boost ? SO whether it's a 5lb or 25lb spring, the CO2 should be able to blow it either way ?
ie, can it not blow the gate open for low boost and blow it shut for high boost ? Does it not operate via closed loop where it trys to maintain the target boost pressure ?
Or is it just a basic open loop setup ?
In the UK, that means less than £5 each.
Then get a few cheap nylon push fit fittings and hose, drill/tap them into the IC end tanks or plumbing, then you can easily hook everything up to test.
Place the two gauges side by side on your dash and go for a blast. Yes you could log via sensors, but it will cost more money unless you can source some cheap OEM map sensors that read a suitable pressure range.
As for the boost controller. Surely with CO2, the mechanical spring pressure becomes irrelevant to max/min boost ? SO whether it's a 5lb or 25lb spring, the CO2 should be able to blow it either way ?
ie, can it not blow the gate open for low boost and blow it shut for high boost ? Does it not operate via closed loop where it trys to maintain the target boost pressure ?
Or is it just a basic open loop setup ?
at this point i have 13psi on the gate when i'm on the break, then i have a pretty aggressive ramp that starts as soon as I'm off the brake and goes to 20psi which it holds throughout the run. (this is pressure that is put on top of the gate, not boost pressure).
01-25-2013, 02:58 AM
#52
9 Second Club
So you're applying 20psi CO2 pressure to the top of the gate to create 20psi of boost pressure ?
So what's the point in using CO2 when it's applying exactly the same as manifold pressure ?
I thought the whole idea of using CO2 was you could supply a much higher pressure across the w/g for more accurate, faster and over a wider range of control of boost pressure.
If you're only going to apply the same as manifold pressure, what's the point ?
The problem could simply be your w/g blowing open due to insufficient top port pressure and/or excessive EGBP
It could also be a very restrictive intercooler, so check that too.
Ideally a boost controller would be closed loop, you set your desired target and the controller will adjust top port pressure to try and maintain that target.
You can do it open loop too as long as your controller allows you to alter w/g duty vs rpm or some other parameter.
So what's the point in using CO2 when it's applying exactly the same as manifold pressure ?
I thought the whole idea of using CO2 was you could supply a much higher pressure across the w/g for more accurate, faster and over a wider range of control of boost pressure.
If you're only going to apply the same as manifold pressure, what's the point ?
The problem could simply be your w/g blowing open due to insufficient top port pressure and/or excessive EGBP
It could also be a very restrictive intercooler, so check that too.
Ideally a boost controller would be closed loop, you set your desired target and the controller will adjust top port pressure to try and maintain that target.
You can do it open loop too as long as your controller allows you to alter w/g duty vs rpm or some other parameter.
01-25-2013, 07:53 AM
#53
So you're applying 20psi CO2 pressure to the top of the gate to create 20psi of boost pressure ?
So what's the point in using CO2 when it's applying exactly the same as manifold pressure ?
I thought the whole idea of using CO2 was you could supply a much higher pressure across the w/g for more accurate, faster and over a wider range of control of boost pressure.
If you're only going to apply the same as manifold pressure, what's the point ?
The problem could simply be your w/g blowing open due to insufficient top port pressure and/or excessive EGBP
It could also be a very restrictive intercooler, so check that too.
Ideally a boost controller would be closed loop, you set your desired target and the controller will adjust top port pressure to try and maintain that target.
You can do it open loop too as long as your controller allows you to alter w/g duty vs rpm or some other parameter.
So what's the point in using CO2 when it's applying exactly the same as manifold pressure ?
I thought the whole idea of using CO2 was you could supply a much higher pressure across the w/g for more accurate, faster and over a wider range of control of boost pressure.
If you're only going to apply the same as manifold pressure, what's the point ?
The problem could simply be your w/g blowing open due to insufficient top port pressure and/or excessive EGBP
It could also be a very restrictive intercooler, so check that too.
Ideally a boost controller would be closed loop, you set your desired target and the controller will adjust top port pressure to try and maintain that target.
You can do it open loop too as long as your controller allows you to alter w/g duty vs rpm or some other parameter.
The main reason you use Co2 is for consistency and to be able to have the boost you want instantly. As soon as the co2 is applied to the gate, it's going to make whatever you're asking it to. This is especially helpful with transbraked turbo cars that need a set boost level on the transbrake so it doesn't creep past that boost psi and cause them to spin. It will also make bringing power in much easier and much more linear. You can bring it in as fast as the turbo can generate enough drive pressure to make the boost pressure you asking of it.
01-25-2013, 09:39 AM
#54
You also have to take into account that I have a spring in each wastegate that makes ~5psi, so 20psi on top of the gate plus the spring in the gate = 20psi of boost at the manifold.
Like Martin said, this controller is a time based setup that simply allows me to set a launch pressure on the gate then as soon as I launch it beings time based stages of pre-determined co2 pressures. It is up to me to figure out how much boost a certain co2 pressure will make and to stage that accordingly. I fully agree that a system that allows me to dial in actual boost numbers then it scales the co2 accordingly would be fantastic, but it's simply not how this unit works.
Like Martin said, this controller is a time based setup that simply allows me to set a launch pressure on the gate then as soon as I launch it beings time based stages of pre-determined co2 pressures. It is up to me to figure out how much boost a certain co2 pressure will make and to stage that accordingly. I fully agree that a system that allows me to dial in actual boost numbers then it scales the co2 accordingly would be fantastic, but it's simply not how this unit works.
01-25-2013, 11:08 AM
#56
Once you use air or co2 you wouldn't go back
And cant really say if it makes 20 psi boost with 20 psi on top of the gate it is a 1:1 drive ratio either
The diaphragm is usually a decent amount larger than the valve so you have to account for that surface area difference
And cant really say if it makes 20 psi boost with 20 psi on top of the gate it is a 1:1 drive ratio either
The diaphragm is usually a decent amount larger than the valve so you have to account for that surface area difference
09-03-2013, 12:13 PM
#58
Another thing to consider or look at might be the converter. In my setup if I have a converter that is slipping bad in the upper rpms I will loose a couple psi of boost also. But when I have a good converter that couples good and has minimal slip it maintains psi better across the rpm band. Just throwing that out there. Ive been testing a bunch of converters lately. I think I've had 8-9 different ones in the truck since March.
09-11-2013, 04:18 PM
#59
Sounds like a typical case of running out of compressor. Thats a lot of cam to feed. Any backpressure is going to hurt performance with an exhaust duration like that but I'm sure its lower than a lot of other setups with those gates and that 5" downpipe. The compressor is just done. When the compressor starts falling off the end of the map, more exhaust energy is used and wasted as heat rather than creating boost pressure.
09-13-2013, 07:24 AM
#60
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Common issue with gate location or backpressure. The ams2000 pro has 10 control strategies. Whatever you use as your primary the rest become offsets to that primary. In your case you could use the time based curve. Then use the engine rpm input as an offset . Example would be set 0 pressure to be added at 4000 rpm and have 5 added at 6000rpm. It interpolates between the two points. Every time it see's this rpm it will automatically add the pressure programmed keeping boost flat.
The 2k is offered in a base unit and a pro unit. Speed based , time, gear , voltage whatever ...it will do it
The 2k is offered in a base unit and a pro unit. Speed based , time, gear , voltage whatever ...it will do it
