Forced Induction's FI91X report!

[Dusty Bradford]

Don. I think it's as much a power/suspension issue more so than the tires. You've really got to get that TRZ anti-roll on the car and get the suspension ready for the power. Time to dig into instant center, shock and spring settings etc.

 

[Alky V6]

Will you be upgrading your cage to 25.5?
Certainly you have to figure you'll be going faster
than 8.50 or you would have bought a smaller turbo.

The short term plan is to get it to 8.50. After it's there, then I'll make the decision what to do next. I went with the 91 because I felt I could make it work to max out the potential of this stage I and then be adequate if I decided to put together my stage II parts. Of course, if I did that, it would mean major chassis changes. Right now, the economy is not cooperating with that plan.

 

[Alky V6]

Don. I think it's as much a power/suspension issue more so than the tires. You've really got to get that TRZ anti-roll on the car and get the suspension ready for the power. Time to dig into instant center, shock and spring settings etc.

I agree with you Dusty. Time to start studying chassis setups. These tires that are on the car now though are way worn. The wear indicators are practically gone. They've been going away for some time now. The 15ws are supposed to be a stiffer sidewall that works well on the heavier cars. Much more stable from the reports I've heard from others that use the tire. We will see.

 

[Otto J]

I agree with you Dusty. Time to start studying chassis setups. These tires that are on the car now though are way worn. The wear indicators are practically gone. They've been going away for some time now. The 15ws are supposed to be a stiffer sidewall that works well on the heavier cars. Much more stable from the reports I've heard from others that use the tire. We will see.

Don you should be dumping them at 20 or so passes and swapping them every 5 or so.
I would bet if you've been losing your hook its the age of the tires more than the new found power

 

[Alky V6]

Don you should be dumping them at 20 or so passes and swapping them every 5 or so.
I would bet if you've been losing your hook its the age of the tires more than the new found power

I was kind of thinking that too. The traction problem seemed to get worse and worse. Should be exciting getting those new tires on there.

 

[Dusty Bradford]

I was kind of thinking that too. The traction problem seemed to get worse and worse. Should be exciting getting those new tires on there.

Oh man. If the wear indicators are gone they're in bad shape A stiff sidewall will get some more life. At your power level your good for about 30+ passes. I get about 25 passes out of the radials at my power level and 3500#. I'd say your weight and power level a stiff sidewall slick should be good for 30-40 passes.

 

[Otto J]

Oh man. If the wear indicators are gone they're in bad shape A stiff sidewall will get some more life. At your power level your good for about 30+ passes. I get about 25 passes out of the radials at my power level and 3500#. I'd say your weight and power level a stiff sidewall slick should be good for 30-40 passes.

With good controlled burnouts,not overheating them.

 

[Alky V6]

With good controlled burnouts,not overheating them.

I understand. I tend to do conservative burnouts and I get prodded by the other guys all the time for not doing a monster burnout. They feel that my traction problems are because I don't do a good enough burnout. MT states it's not necessary and I tend to believe the fellas that designed the tire.

 

[Otto J]

I understand. I tend to do conservative burnouts and I get prodded by the other guys all the time for not doing a monster burnout. They feel that my traction problems are because I don't do a good enough burnout. MT states it's not necessary and I tend to believe the fellas that designed the tire.

Exactly mu point Don,Watch Guys like Tim Lynch who run in the 6s on 10.5s(a little wide they are) but his burnout is the minimal ive seen and his car hooks very well.

 

[Quint]

I understand. I tend to do conservative burnouts and I get prodded by the other guys all the time for not doing a monster burnout. They feel that my traction problems are because I don't do a good enough burnout. MT states it's not necessary and I tend to believe the fellas that designed the tire.

One thing I have noticed with my PT91.5, is that if the converter is to tight, the power just hits the tires to fast and to hard. Dusty losen'd the converter and that fixed the initial hit. The Drag Radials im running now, along with the converter fix, has gotten me some very nice 1.27-1.35 60fts, with out the aid of Coil overs, adjustable shocks. If course we have the nitrous only on spool up, once i let go of the transbreak, it shuts off. Yes, to big of burnouts, can kill your traction with this power level. The boost controller is a life saver, but make sure its not set with to much lag time between the launch stage and the 2-3 stages. Im telling you, if the converter is perfect, then the power will take care of the rest of the run. You will launch, but nothing to crazy on the tires, you grab 2nd and just hang on. 8.50's isnt hard, if the convrter is right and the shifts are on time with a decent 1.39 and under 60ft, carrying 160+ out the back door

 

[Alky V6]

One thing I have noticed with my PT91.5, is that if the converter is to tight, the power just hits the tires to fast and to hard. Dusty losen'd the converter and that fixed the initial hit. The Drag Radials im running now, along with the converter fix, has gotten me some very nice 1.27-1.35 60fts, with out the aid of Coil overs, adjustable shocks. If course we have the nitrous only on spool up, once i let go of the transbreak, it shuts off. Yes, to big of burnouts, can kill your traction with this power level. The boost controller is a life saver, but make sure its not set with to much lag time between the launch stage and the 2-3 stages. Im telling you, if the converter is perfect, then the power will take care of the rest of the run. You will launch, but nothing to crazy on the tires, you grab 2nd and just hang on. 8.50's isnt hard, if the convrter is right and the shifts are on time with a decent 1.39 and under 60ft, carrying 160+ out the back door

Do you mean the torque multiplication factor was too high with the original T/C? I don't see how a low stall T/C, if it has a tame torque multiplication factor will cause the tires to hit too hard at the launch.

 

[Alky V6]

Quint. You may have just had too high a torque multiplication factor with your previous T/C. Taming down the torque multiplication factor alone will make most T/Cs more efficient on the top end. It's one of those trade off deals with a T/C. You can have crazy torque multiplication, if you need it, for the launch, but less efficiency on the top end,... or less torque multiplication, as would be in a case where you have more than enough power from the engine for digging out of the hole, and as a natural result of going with less torque multiplication, better efficiency during coupling.

Torque multiplication and stall speed are treated separately in a torque converter. Although, they do have an effect on each other.

 

[Alky V6]

That's one of the reasons I've stuck with the N/C for so long. It's a low stall with a very tame torque multiplication factor. So much so to a fault. I think getting the right shot size will make up for it though.
What I'm hoping to end up with is a shot size that will yield me a 1.3 or so 60 foot and 8 psi in something less than 2 seconds nitrous hit time. All the changes so far have been working in the right direction. Small steps. Judging by the testing up to this point, I have no doubt I'll reach my goal with this turbo.

 

[Alky V6]

One of the nice things about using nitrous to spool the turbo is I'm not having to go through a bunch of torque converters to get things tuned in the way I want. When I first ordered the T/C, they were told about the use of nitrous to get things going. I tend to think they did pretty good on setting this thing up. All I need to do is simply tune the nitrous system to the requirements of the T/C to make it work.

Imagine having a small cid V6 and going from a T76 to a 91 and using the same T/C. Normally that would be unthinkable. A T/C stall change or some other T/C change would be at the top of the list for most. So far, I've knocked the nitrous hit up by 45 hp and it's moved the tuneup much closer to where it needs to be than I thought possible. Luckily the 60 foot and the target of getting to 8 psi boost within 2 seconds are moving together rather well, relative to each other, with the nitrous hit changes up to this point.

 

[Chevota]

One of the nice things about using nitrous to spool the turbo is I'm not having to go through a bunch of torque converters to get things tuned in the way I want. When I first ordered the T/C, they were told about the use of nitrous to get things going. I tend to think they did pretty good on setting this thing up. All I need to do is simply tune the nitrous system to the requirements of the T/C to make it work.

Imagine having a small cid V6 and going from a T76 to a 91 and using the same T/C. Normally that would be unthinkable.

I agree, but I hope you keep that bottle temp consistent or the spool up tune is gonna get ugly real fast!

 

[Alky V6]

I agree, but I hope you keep that bottle temp consistent or the spool up tune is gonna get ugly real fast!

That's one of the beauties of pairing nitrous with methanol rather than gasoline. With the wide tuning range of alcohol, you just setup the mixture to be safe with the highest anticipated bottle pressure, usually 1050 psi, but it can be higher, and the mixture is still workable at bottle pressures as low as 800 psi. On really cold days it can even get under 800 psi. The lowest bottle pressure that I've run with has been 750 psi. That's another thing on my wish list. A 115V heat blanket for the bottle. The 12V system tied into the car electrical just doesn't do it.
When I tune the nitrous system to the point of rich missing with a cold bottle and then go up one size on the nitrous jets, the rich missing disappears and the mixture will be safe up to and over 1050 psi. When I catch the bottle pressure being over 1050 psi before staging, I'll try to purge the pressure down as close as possible to 1050 psi. Although, it's not disasterous if the pressure is over 1050.

 

[Alky V6]

Here's a tuning tip for anyone wanting to play with nitrous and alcohol.

I target a nitrous/alcohol ratio of 1.7-2.0:1.
Rich missing is encountered under 1.7:1.

 

[Chevota]

Here's a tuning tip for anyone wanting to play with nitrous and alcohol.

I target a nitrous/alcohol ratio of 1.7-2.0:1.
Rich missing is encountered under 1.7:1.

From a gas tuners perspective, I stand corrected.

 

[Quint]

Quint. You may have just had too high a torque multiplication factor with your previous T/C. Taming down the torque multiplication factor alone will make most T/Cs more efficient on the top end. It's one of those trade off deals with a T/C. You can have crazy torque multiplication, if you need it, for the launch, but less efficiency on the top end,... or less torque multiplication, as would be in a case where you have more than enough power from the engine for digging out of the hole, and as a natural result of going with less torque multiplication, better efficiency during coupling.

Torque multiplication and stall speed are treated separately in a torque converter. Although, they do have an effect on each other.

Yes, makes Sense Don. Your right on the button. I have been pondering the idea of going an extra 50shot of nos on the transbreak for a total of 150 shot. This would get me to my 12 pounds a little faster for sure.

 

[Dusty Bradford]

Setting a turbo converter up knowing a customer will use nitrous for spooling makes the process much easier. You can focus less on spooling and more on efficiency.

What Don has stated is why different converters work so differently from various manufacturers. I look at it from another angle. I want the easiest spooling converter that will deliver the best et and mph possible. I really see it as complicating issues if you have a converter that is hard to get on boost vs easier when they deliver the same et and mph.

I try in all cases to get a car on boost without the use of any sort of nitrous or variable stall. It's not always possible though as in Don and Quints cases.