Rotrex Supercharger thread
09-25-2012, 04:02 PM
#76
Rennlist Member
No... I don't think anyone knows for sure what the limit is. Yes the MAF is maxed out at around 400WHP. The single disc clutch also seems to crap out around 400 WHP. Everything else, so far seems to be able to go well beyond that. Does that mean it was designed for that level? Probably not, but who cares.
What is the limit? I think we are still finding out. Todd T is putting 825 HP at the wheels with a stock motor (never opened up) and stock transmission. So far so good.
I am running pretty damn near 500 at the wheels. And my system is probably the most demanding on the drivetrain with the low torque I make. But so far it's holding up. I hope it continues for a very long time too!
I think the rotrex, turbo, or vortech kits are much easier on the drivetrain components because the boost come on more gradually and thus should be able to withstand a lot of abuse for a long time.
What is the limit? I think we are still finding out. Todd T is putting 825 HP at the wheels with a stock motor (never opened up) and stock transmission. So far so good.
I am running pretty damn near 500 at the wheels. And my system is probably the most demanding on the drivetrain with the low torque I make. But so far it's holding up. I hope it continues for a very long time too!
I think the rotrex, turbo, or vortech kits are much easier on the drivetrain components because the boost come on more gradually and thus should be able to withstand a lot of abuse for a long time.
What are the MAF limit workarounds?
09-25-2012, 04:10 PM
#77
I am definitely concerned about the longevity of the transmission, as well as clutch slip, with adding power. Both issues drove me nuts on my Saab 900 turbo project to the point that I moved on to a car that could handle more power... the 928!
What are the MAF limit workarounds?
What are the MAF limit workarounds?
09-25-2012, 04:46 PM
#78
Under the Lift
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Yeah, I think this is wrong. There is not a consistent relationship between the MAF signal % (or MAF voltage) and the MAF signal absolute. So, you need to look at the MAF signal absolute number, not %. You would only estimate 450 CHP if you hit a MAF signal absolute of 516 at 6000 RPM.
09-25-2012, 04:57 PM
#79
Race Car
I can tell you for a fact that a GT transmission, stock dual-disc clutch, unopened GT engine and all stock GT drivetrain bits will last a long long time at 420rwhp. How long? Well, I have over 75k miles on the supercharger on the GT right now and it's still going strong. Good tuning is key for engine longevity. I can also tell you that a stock single-disc clutch, including a GTS clutch, won't take the abuse for long.
Dan
'91 928GT S/C
475hp/460lb.ft
09-25-2012, 06:31 PM
#83
Rennlist Member
The MAF % is the same scale as MAF Signal Absolute. i.e. 100% MAF signal = MAF signal absolute at 516, the bottom row of the fuel map
It is MAF volts on the screen that limits out at Vmaf = 5.2v when in fact there is still some headroom up to 6.1v by some clever tricks we use ..... and this higher volts corresponds to around 450CHP
It is MAF volts on the screen that limits out at Vmaf = 5.2v when in fact there is still some headroom up to 6.1v by some clever tricks we use ..... and this higher volts corresponds to around 450CHP
Yeah, I think this is wrong. There is not a consistent relationship between the MAF signal % (or MAF voltage) and the MAF signal absolute. So, you need to look at the MAF signal absolute number, not %. You would only estimate 450 CHP if you hit a MAF signal absolute of 516 at 6000 RPM.
09-25-2012, 06:32 PM
#84
Rennlist Member
Join Date: Oct 2009
Location: Michigan... Grand Rapids
Posts: 758
Likes: 0
Received 2 Likes
on
1 Post
Yeah, I think this is wrong. There is not a consistent relationship between the MAF signal % (or MAF voltage) and the MAF signal absolute. So, you need to look at the MAF signal absolute number, not %. You would only estimate 450 CHP if you hit a MAF signal absolute of 516 at 6000 RPM.
Here is a data log taken from the shark tuner while I was doing a tuning run with the stock MAF. As you can see the MAF% hits 100% When I am round 5000/5100 rpms and stays flatlined as the rpms continue to climb. Are you saying that the absolute numbers are still going up even though the % is staying at 100??
Oh and btw, for everyone interested the boot level at 100%maf was 6.7lbs
09-25-2012, 06:32 PM
#85
Rennlist Member
09-25-2012, 06:39 PM
#86
Rennlist Member
Join Date: Oct 2009
Location: Michigan... Grand Rapids
Posts: 758
Likes: 0
Received 2 Likes
on
1 Post
The MAF % is the same scale as MAF Signal Absolute. i.e. 100% MAF signal = MAF signal absolute at 512, the bottom row of the fuel map
It is MAF volts on the screen that limits out at Vmaf = 5.2v when in fact there is still some headroom up to 6.1v by some clever tricks we use ..... and this higher volts corresponds to around 450CHP
It is MAF volts on the screen that limits out at Vmaf = 5.2v when in fact there is still some headroom up to 6.1v by some clever tricks we use ..... and this higher volts corresponds to around 450CHP
So John, it sounds like you are saying that 100% or 5.2 volts in not 450chp? and that 6.1 is 450chp??? Hmmm by my calculations the 5.2 would only be about 385chp then
09-25-2012, 06:51 PM
#87
Rennlist Member
Sorry if I was not clear.
"MAF volts" on the screen display will start to hit max and limit at 5.2v (which may be 400HP) although other MAF processing circuits in the LH ECU work up to MAF = 6.1v.
But 100% = 6.1v = MAF signal absolute 512 at about 450HP crank.
The SMAF is good for over 800HP :-)
"MAF volts" on the screen display will start to hit max and limit at 5.2v (which may be 400HP) although other MAF processing circuits in the LH ECU work up to MAF = 6.1v.
But 100% = 6.1v = MAF signal absolute 512 at about 450HP crank.
The SMAF is good for over 800HP :-)
09-25-2012, 07:18 PM
#88
Rennlist Member
Join Date: Oct 2009
Location: Michigan... Grand Rapids
Posts: 758
Likes: 0
Received 2 Likes
on
1 Post
Sorry if I was not clear.
"MAF volts" on the screen display will start to hit max and limit at 5.2v (which may be 400HP) although other MAF processing circuits in the LH ECU work up to MAF = 6.1v.
But 100% = 6.1v = MAF signal absolute 512 at about 450HP crank.
The SMAF is good for over 800HP :-)
"MAF volts" on the screen display will start to hit max and limit at 5.2v (which may be 400HP) although other MAF processing circuits in the LH ECU work up to MAF = 6.1v.
But 100% = 6.1v = MAF signal absolute 512 at about 450HP crank.
The SMAF is good for over 800HP :-)
As you can see from my plot, things go a bit wrong after after the MAF hits 100%, the LH doesnt know what to do, and I got knocks. The fuel % just kinda jumps around not knowing how much fuel to inject without the MAF. Really the only way to correctly handle this is with with one of Johns superMAFs, and click the box in your sharktuner for supermaf. You can also trick the MAF with something like the Murf doughnut.
The only temporary way I have found to handle this and continue to add more fuel is with the WOT map. At that point (100%maf) I started cranking in the fuel with the WOT map and it helped in that later runs with fuel ratio and knocks.
09-25-2012, 07:20 PM
#89
Rennlist Member
Thread Starter
Victor, since I have the 75mm pulley, does that mean I might be pushing 8lbs boost? I've not installed my gauges yet so I have no idea on actual.
09-25-2012, 07:21 PM
#90
Rennlist Member
Thread Starter
