FI-98X....question
09-21-2011, 12:58 AM
#1
FI-98X....question what cubic inch for fast spool-up....least amount of lag possible....
408ci
416ci
422ci
Says its rated at 1650 HP............like to maybe pound an LSX iron block with it.........
Curious how one gets rid of lag or almost gets rid of it............
.
408ci
416ci
422ci
Says its rated at 1650 HP............like to maybe pound an LSX iron block with it.........
Curious how one gets rid of lag or almost gets rid of it............
.
09-21-2011, 01:03 AM
#2
Lag is there just to give the other guy enough time to think he's winning before you remind him he should of nailed his doors shut as you blow by him.
Turbo lag is enevitable it's how they work, but once the power comes on, beleive you me, the last thing on your mind will be turbo lag.
With that said I'd go smallest C.I. possible as to have the least amount of backpressure possible. Turbo's operate best when backpressure equals boost pressure in a 1:1 ratio. When you get rid of lag completely or close to it, it means your about to reach the max potential of your turbo and it really isn't operating at it's full potential.
After reading that last sentence I wrote that isn't always true as a well matched combo, with the proper converter and gear will spool very quickly while still having a nice top end.
Turbo lag is enevitable it's how they work, but once the power comes on, beleive you me, the last thing on your mind will be turbo lag.
With that said I'd go smallest C.I. possible as to have the least amount of backpressure possible. Turbo's operate best when backpressure equals boost pressure in a 1:1 ratio. When you get rid of lag completely or close to it, it means your about to reach the max potential of your turbo and it really isn't operating at it's full potential.
After reading that last sentence I wrote that isn't always true as a well matched combo, with the proper converter and gear will spool very quickly while still having a nice top end.
09-21-2011, 01:07 AM
#3
Lag is there just to give the other guy enough time to think he's winning before you remind him he should of nailed his doors shut as you blow by him.
Turbo lag is enevitable it's how they work, but once the power comes on, beleive you me, the last thing on your mind will be turbo lag.
With that said I'd go smallest C.I. possible as to have the least amount of backpressure possible. Turbo's operate best when backpressure equals boost pressure in a 1:1 ratio. When you get rid of lag completely or close to it, it means your about to reach the max potential of your turbo and it really isn't operating at it's full potential.
Turbo lag is enevitable it's how they work, but once the power comes on, beleive you me, the last thing on your mind will be turbo lag.
With that said I'd go smallest C.I. possible as to have the least amount of backpressure possible. Turbo's operate best when backpressure equals boost pressure in a 1:1 ratio. When you get rid of lag completely or close to it, it means your about to reach the max potential of your turbo and it really isn't operating at it's full potential.
.
09-21-2011, 01:39 AM
#6
I guess if I'm gonna do a roll race....it'll be spooled up before the start of the run.
.
09-21-2011, 03:43 AM
#7
Fighting lag issues and building boost is something it seems people fight with when running a bigger turbo; sort of one of those compromises for being able to run more boost and make more power; that part is inevitable.
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09-21-2011, 06:08 AM
#8
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oh...and the 98x is rated at 1975hp...
09-21-2011, 08:53 AM
#10
Excuse me if Im wrong here but for someone who wants a bigger turbo and instant response or little lag in the setup, wouldnt a bigger cube motor be more suitable for those needs? It is know that the bigger the cubes of a motor, the more low end torque the engine would produce (everything else being the same internally between the two). So wouldnt this extra low end "kick" help spool the turbo up quicker, or at least get it going good enough to make a difference in how the turbo spools? I understand you want it to be efficient with the setup and near 1:1 but OP is looking for something with little lag which isnt always the combo that is going to make the fastest runs at the track... What Im saying is, sometimes you compromise.
Fighting lag issues and building boost is something it seems people fight with when running a bigger turbo; sort of one of those compromises for being able to run more boost and make more power; that part is inevitable.
Fighting lag issues and building boost is something it seems people fight with when running a bigger turbo; sort of one of those compromises for being able to run more boost and make more power; that part is inevitable.
09-21-2011, 12:29 PM
#12
If someone has a goal of making 1,300 RWHP....how do you choose a turbo given those maximum HP ratings. AND not wanting to run a turbo to its max and have it breathing on the edge of its capabilities?
This was my next question today........you said above in your post, "match the a/r of the turbine housing to engine size."
How is this done so I can choose the proper combo before hand????
Maybe I'm asking for too much.......I want an engine that I can drive around casually if I want to, driving it like any normal car, not having the turbo smacking me in the *** when it his its "so called" sweet spot where it starts making boost..........but when I want to run it from 50-160mph thats where I want it to perform at its best.
.
09-21-2011, 12:45 PM
#13
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either pick a turbo and design the engine around it or pick the engine and design a turbo around it...
you have two indepedant variables and have to fix one to come up with a solution. For example, I would not run a pt88 on anything over 350-360 cubes personally...otherwise you run out of compressor and the back pressure becomes a bitch.
you have two indepedant variables and have to fix one to come up with a solution. For example, I would not run a pt88 on anything over 350-360 cubes personally...otherwise you run out of compressor and the back pressure becomes a bitch.
09-21-2011, 12:48 PM
#15
either pick a turbo and design the engine around it or pick the engine and design a turbo around it...
you have two indepedant variables and have to fix one to come up with a solution. For example, I would not run a pt88 on anything over 350-360 cubes personally...otherwise you run out of compressor and the back pressure becomes a bitch.
you have two indepedant variables and have to fix one to come up with a solution. For example, I would not run a pt88 on anything over 350-360 cubes personally...otherwise you run out of compressor and the back pressure becomes a bitch.
09-21-2011, 01:18 PM
#16
either pick a turbo and design the engine around it or pick the engine and design a turbo around it...
you have two indepedant variables and have to fix one to come up with a solution. For example, I would not run a pt88 on anything over 350-360 cubes personally...otherwise you run out of compressor and the back pressure becomes a bitch.
you have two indepedant variables and have to fix one to come up with a solution. For example, I would not run a pt88 on anything over 350-360 cubes personally...otherwise you run out of compressor and the back pressure becomes a bitch.
I want to reach a goal of 1,300 RWHP through a 4L80E. HP is what makes a roll racer.
FI91X seems like the choice in turbo, given its max rating of 1650 HP. So what cubic inch, heads and cam.
Gonna use the LSX iron block and 6 bolt heads....so I'm good there anyway.....
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Last edited by LS6427; 09-21-2011 at 02:00 PM.
09-21-2011, 02:40 PM
#18
I'm asking about fast spooling because I "assume" the faster an engine can spool its turbo the closer to an N/A feel it will have. I see these twin-turbo engines on the dyno that NRE builds....when they snap the throttle its like an N/A engine, like no lag, yet they're making 1,600 HP 402ci with the LSX iron block, so it doesn't seem they're running out of compressor.
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