AGP Back pressure data

[hillshooter]

Anyone have any back pressure data from their AGP kit? I would also look at huron twin kit or something similar. Any size engine or turbos .

I now have a back pressure sensor and will have hard data very soon that I will upload to this thread.

[hillshooter]

LS3 416 on E85. AGP twin 68's with .82 A/R. Holley shorty headers. Holley terminator engine management. custom cold side plumbing.

Back pressure fluctuates between 39 and spikes to 45 in this example and boost maintains a solid 21-22 PSI of manifold pressure.

I would sill love to see other comparisons. Other turbo owners you are flying blind if you don't have this data. Its crazy to me I can post on a forum this size and get zero replies, there has to be countless turbo cars.

Imagine if my back pressure is 2:1, what are the guys running 58MM turbos? or smaller A/R's or stock manifolds. Lets see your data! Lets see a smaller displacement engine with the big AGP kit.

[mrimpala02]

I don't think it is that people are ignoring your thread, but rather we don't have access to the same data. I have a AGP kit on SBE with 62/65. Of course way too much turbo for my engine, but I was planning ahead. I do not have actual back pressure data to report, but I can tell you when was 93 + meth with 3" spintech mufflers I made ~7XX rwhp @ 15 psi. I then did a muffler delete for sound purposes and eventually switched to e85 + meth. Now I am at 906 rwhp @ 14 psi. It really is too many variables changed to give credit to one of them.

[ttshovel]

Apples to oranges here. I don't have a backpressure gauge. I just figure it out by using co2 dome pressure vs boost.

It was 1.5-1.6:1 @ 25psi for me using truck manifolds and the monster single. Getting up to 30-32 it was closer to 2:1. Switching to 1 and 7/8 primary tube turbo headers so will be interesting to see the comparison

[hillshooter]

Originally Posted by mrimpala02

I don't think it is that people are ignoring your thread, but rather we don't have access to the same data. I have a AGP kit on SBE with 62/65. Of course way too much turbo for my engine, but I was planning ahead. I do not have actual back pressure data to report, but I can tell you when was 93 + meth with 3" spintech mufflers I made ~7XX rwhp @ 15 psi. I then did a muffler delete for sound purposes and eventually switched to e85 + meth. Now I am at 906 rwhp @ 14 psi. It really is too many variables changed to give credit to one of them.

Thank you for the response. You say too much turbo for your engine but I would disagree. I would say its probably perfect. This is the type of setup I am really curious about back pressure in.

[mrimpala02]

Originally Posted by hillshooter

Thank you for the response. You say too much turbo for your engine but I would disagree. I would say its probably perfect. This is the type of setup I am really curious about back pressure in.

Agreed it would be interesting data. But I'm hoping to recoup some money from this stock bottom end block, rather then having to scrap it.

[hillshooter]

Originally Posted by ttshovel

Apples to oranges here. I don't have a backpressure gauge. I just figure it out by using co2 dome pressure vs boost.

It was 1.5-1.6:1 @ 25psi for me using truck manifolds and the monster single. Getting up to 30-32 it was closer to 2:1. Switching to 1 and 7/8 primary tube turbo headers so will be interesting to see the comparison

I would love to see what this change does. Keep us informed please

[stevieturbo]

Get a Mityvac, and verify what you are seeing at the ecu is correct.

better still, pump air into both the MAP sensor and the pre-turbine pressure sensor at the same time to verify readings at the ecu.

Because the pressure you're seeing there....seems unusually high unless you've a very small turbine housing or something.

I've a 383 with a pair of 364's ( DIY truck manifold twins ), and until 6500rpm and/or 25psi boost, I'm less than 1:1 pressure ratio.

[hillshooter]

Originally Posted by stevieturbo

Get a Mityvac, and verify what you are seeing at the ecu is correct.

better still, pump air into both the MAP sensor and the pre-turbine pressure sensor at the same time to verify readings at the ecu.

Because the pressure you're seeing there....seems unusually high unless you've a very small turbine housing or something.

I've a 383 with a pair of 364's ( DIY truck manifold twins ), and until 6500rpm and/or 25psi boost, I'm less than 1:1 pressure ratio.

I have used two different sensors plugged into two different inputs of my Holley to verify calibration. so I knows its correct. I also checked at many boost levels, in fact its 1.7:1 at 10 pounds of boost and creeps up to 2:1 as I get higher.

The elephant in the room is not the turbine size or the A/R of the turbine, in my opinion with all of my variables, the issue is the AGP turbine adapter adding the restriction.

Still 2:1 is great at 25 pounds on a 416. Its really making some steam.

[stevieturbo]

And clearly you do not understand what is meant about verifying a calibration !

You could plug a hundred sensors on....that isnt verifying it's calibration within the ecu for that sensor is correct.

Test it properly from a known calibrated pressure source to make sure any readings you see on the ecu, match.

2:1 is terrible on a twin setup and if you are measuring at the turbine inlet, any restriction at the extension is irrelevant. And 1.7:1 at only 10psi is even worse.

If you are measuring prior to the extension, then yes, any restriction there would be visible.

In which case...measure both prior to the extension and at the turbine inlet and see if there is a pressure drop across it.

[hillshooter]

Let me be more clear. I have a fuel pressure sensor that is 0-100, it is calibrated against a mechanical gauge in the fuel rail. That fuel pressure sensor uses the same 3 wire 0-100 sensor as my back pressure gauge does. I calibrated and tested the back pressure sensor using and swapping between the fuel pressure input to verify validity. My data is good and yes I would love to be less than 2:1 but at least its not 3:1. Thats why I am here looking for other opinions so I do value yours.

thats a good point to check at the turbine, I will have to look into that.