Spool and Lag
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From: Where Geos Go Fast, 95355
Re: Spool and Lag (Bailhatch)
as long as the car has enough power naturally aspirated for cruising at 70-80 MPH, i dont care when the turbo spools, just as long as when you shift in redline you can keep full boost (dont drop out of powerband)
i think you get best gas mileage this way, and when you have all wheel drive, like i do in my personal car, traction problems are virtually non-existant.
i think you get best gas mileage this way, and when you have all wheel drive, like i do in my personal car, traction problems are virtually non-existant.
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Re: Spool and Lag (0x64)
Lag
1. To fail to keep up a pace; straggle.
2. To proceed or develop with comparative slowness
3. To cause to hang back or fall behind
4. A condition of slowness or retardation.
Drag Race
1. A race between two cars to determine which can accelerate faster from a standstill
Why would u want lag, a condition of slowness, something that causes you to hang back or fall behind, and not allow you to keep up a pace in a Drag Race, where you are trying to accelerate faster then another car?
This whole idea of Lag aiding in traction is complete nonsense. Lag is when you are accelerating slow. Period. You have traction because you are not accelerating fast. When boost comes on whether it be at 3k rpm or at 6k rpm, if it is too much torque for your tires to handle; they will loose traction...
Another pet peave I see in this post is the idea that a flat torque curve to redline is an optimal powerband. Like Art said earlier, all this means is that you are shifting your car too early! You have to understand how gearing/torque accelerate your car. <U>If your torque has not fallen off and ur HP has not kneeled over then you are still accelerating</U>! If you shift to the next gear you are missing out on alot of acceleration that you still had left in the previous gear.
I think alot of people on this site underestimate the benifit's of a <U>properly</U> sized turbo. People are so infactuated with making great #'s per pound of boost and having "future potential," that they forget what they started out to do; which i think is to win races. Picking a turbo is not that complicated. Big horsepower is only part of the equation, boost response and area under the curve are just as important.
1. To fail to keep up a pace; straggle.
2. To proceed or develop with comparative slowness
3. To cause to hang back or fall behind
4. A condition of slowness or retardation.
Drag Race
1. A race between two cars to determine which can accelerate faster from a standstill
Why would u want lag, a condition of slowness, something that causes you to hang back or fall behind, and not allow you to keep up a pace in a Drag Race, where you are trying to accelerate faster then another car?
This whole idea of Lag aiding in traction is complete nonsense. Lag is when you are accelerating slow. Period. You have traction because you are not accelerating fast. When boost comes on whether it be at 3k rpm or at 6k rpm, if it is too much torque for your tires to handle; they will loose traction...
Another pet peave I see in this post is the idea that a flat torque curve to redline is an optimal powerband. Like Art said earlier, all this means is that you are shifting your car too early! You have to understand how gearing/torque accelerate your car. <U>If your torque has not fallen off and ur HP has not kneeled over then you are still accelerating</U>! If you shift to the next gear you are missing out on alot of acceleration that you still had left in the previous gear.
I think alot of people on this site underestimate the benifit's of a <U>properly</U> sized turbo. People are so infactuated with making great #'s per pound of boost and having "future potential," that they forget what they started out to do; which i think is to win races. Picking a turbo is not that complicated. Big horsepower is only part of the equation, boost response and area under the curve are just as important.
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Re: Spool and Lag (Bailhatch)
I remember having a conversation with tony1 awhile back and I remember saying something about having a larger turbo partially for traction issues . . . then he showed me the light to the gear dependant boost controllers. What I run into problems with is that I want something to spool quickly so I can have a usable powerband, BUT I dont want waste all that for a bunch of wheelspin. I guess a G.D.B.C. could solve this but I dont know.
<--------- a guy that cant make up his mind between a SC34 and SC61
<--------- a guy that cant make up his mind between a SC34 and SC61
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From: Planet BOOOST
Re: Spool and Lag (integra_gsr98)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by integra_gsr98 »</TD></TR><TR><TD CLASS="quote">I am also wondering if anyone that wants "lag" to aid in traction has ever driven a high HP FWD car. Whether full boost hits at 5k rpm or 3k rpm you still have traction problems.
Drive down the interstate in a 350+ whp car in third gear and step on it. As soon as it spools it will light the front tires up instantly. Art has it right... learn to drive the car with the setup that you choose to use.</TD></TR></TABLE>
True but if it fully spools higher up the RPM range the car would have gained more speed and you may well still spin depending on the size of the turbo of course, but it will be less and you will have that bit more traction at a higher speed than you would at a lower speed as the car is already in higher motion.
Drive down the interstate in a 350+ whp car in third gear and step on it. As soon as it spools it will light the front tires up instantly. Art has it right... learn to drive the car with the setup that you choose to use.</TD></TR></TABLE>
True but if it fully spools higher up the RPM range the car would have gained more speed and you may well still spin depending on the size of the turbo of course, but it will be less and you will have that bit more traction at a higher speed than you would at a lower speed as the car is already in higher motion.
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From: A Place in, Florida, USA
Re: Spool and Lag (DIRep972)
Maybe I should of phrased my post another way. Yes I should of. This thread was misconstrued by some people but I guess that's no one's fault but my own. <edit>I really meant that I don't prefer turbochargers where the power starts falling off at 6500RPM when you can safely rev to 8200RPM. People get worried about making full boost at X RPM even if they are making less power at X high RPM than X low RPM. Probably doesn't make sense to some</edit>.
Misconstrued
1. To construe wrongly; to interpret erroneously.
Misconstrued
1. To construe wrongly; to interpret erroneously.
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From: Third Coast, united states
Re: Spool and Lag (0x64)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 0x64 »</TD></TR><TR><TD CLASS="quote">I really meant that I don't prefer turbochargers where the power starts falling off at 6500RPM when you can safely rev to 8200RPM. </TD></TR></TABLE>
Do you understand though that if your power is peaking at 8200rpm there is still acceleration left in it if you keep revving it?
Do you understand though that if your power is peaking at 8200rpm there is still acceleration left in it if you keep revving it?
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From: ME
Re: Spool and Lag (0x64)
Can anyone lay out a comparison of how changing turbine specs changes flow and spool like how would upping the wheel from 50trim to 60 trim compare to upping the A/R ratio from .42 to .63?
I'm under the impression they have similar affects in that increasing either will gain flow at the expense of fast spool. What are the nuances of these changes and which would be more desiarable for what type of needs/wants? ie.
I'm under the impression they have similar affects in that increasing either will gain flow at the expense of fast spool. What are the nuances of these changes and which would be more desiarable for what type of needs/wants? ie.
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From: Third Coast, united states
Re: Spool and Lag (Bailhatch)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bailhatch »</TD></TR><TR><TD CLASS="quote">Can anyone lay out a comparison of how changing turbine specs changes flow and spool like how would upping the wheel from 50trim to 60 trim compare to upping the A/R ratio from .42 to .63?
I'm under the impression they have similar affects in that increasing either will gain flow at the expense of fast spool. What are the nuances of these changes and which would be more desiarable for what type of needs/wants? ie. </TD></TR></TABLE>
As long as you have a properly sized compressor wheel, the turbine side makes a larger difference on where and how the power will be made. I will use an example to show what I mean.(this is not exact or anything but just some educated guesses im making for a basic low boost turbo B series.)
Say ur running this turbo: .48ar housing w/ stage 2 turbine wheel and 50 trim compressor wheel.
-You swap the 50 trim compressor wheel to a 60 trim; you will see a little more peak power and very little gain in lag. (10-20hp, 100rpm's lag)
-Now you swap the turbine wheel to a stage 3; you see an even larger gain in power then you did by swapping the compressor wheels but you also see a larger gain in lag. (20-30hp, 300rpm's lag)
-Then you change the exhaust housing from a .48 to a .63; you see another big gain in peak power, about as large as you did by swapping the turbine wheels, but you also see an even larger gain in lag then you did by swapping the turbine wheel. (20-30hp, 500rpm's lag)
I'm under the impression they have similar affects in that increasing either will gain flow at the expense of fast spool. What are the nuances of these changes and which would be more desiarable for what type of needs/wants? ie. </TD></TR></TABLE>
As long as you have a properly sized compressor wheel, the turbine side makes a larger difference on where and how the power will be made. I will use an example to show what I mean.(this is not exact or anything but just some educated guesses im making for a basic low boost turbo B series.)
Say ur running this turbo: .48ar housing w/ stage 2 turbine wheel and 50 trim compressor wheel.
-You swap the 50 trim compressor wheel to a 60 trim; you will see a little more peak power and very little gain in lag. (10-20hp, 100rpm's lag)
-Now you swap the turbine wheel to a stage 3; you see an even larger gain in power then you did by swapping the compressor wheels but you also see a larger gain in lag. (20-30hp, 300rpm's lag)
-Then you change the exhaust housing from a .48 to a .63; you see another big gain in peak power, about as large as you did by swapping the turbine wheels, but you also see an even larger gain in lag then you did by swapping the turbine wheel. (20-30hp, 500rpm's lag)
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Re: Spool and Lag (Bailhatch)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bailhatch »</TD></TR><TR><TD CLASS="quote">Can anyone lay out a comparison of how changing turbine specs changes flow and spool like how would upping the wheel from 50trim to 60 trim compare to upping the A/R ratio from .42 to .63?
I'm under the impression they have similar affects in that increasing either will gain flow at the expense of fast spool. What are the nuances of these changes and which would be more desiarable for what type of needs/wants? ie. </TD></TR></TABLE>
I plan on doing alot of testing on turbos with the new engine dyno that is almost done:
I'm under the impression they have similar affects in that increasing either will gain flow at the expense of fast spool. What are the nuances of these changes and which would be more desiarable for what type of needs/wants? ie. </TD></TR></TABLE>
I plan on doing alot of testing on turbos with the new engine dyno that is almost done:
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From: 648 at 8,500
Re: Spool and Lag (Arturbo)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Arturbo »</TD></TR><TR><TD CLASS="quote">
I plan on doing alot of testing on turbos with the new engine dyno that is almost done:
</TD></TR></TABLE>
Is that Larry's shop? That is awesome! Do I smell a turbo manifold shootout? 
EDIT- I see an Endyn sticker. Question answered.
I plan on doing alot of testing on turbos with the new engine dyno that is almost done:
</TD></TR></TABLE> Is that Larry's shop? That is awesome! Do I smell a turbo manifold shootout? EDIT- I see an Endyn sticker. Question answered.
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From: Where Geos Go Fast, 95355
Re: Spool and Lag (Arturbo)
Better be snapping some vids there, art.. engine dynos rule, but too expensive to pay to have someone do it, that is unless you only do honda motors or something 
That'd be cool to be able to get a "crate" honda engine, with programmed ECU and a dyno sheet, no?
ehh, second thought it would make things to easy!
That'd be cool to be able to get a "crate" honda engine, with programmed ECU and a dyno sheet, no?
ehh, second thought it would make things to easy!
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From: Hot Hot Heat, AZ
smaller turbos like the t25 are great for street cars if you want instant torque. my old t25bb was fun, but imo it felt like i could shift at the redline of the turbo instead of the motor. you can build a very fast street car by using a GT turbo that uses lightweight turbine wheels/shafts with comp wheels that make a little more power. for instance, there is the GT28R. it uses a 62 trim comp wheel with a .60 A/R TO4B(?) housing and a 76 trim GT25 turbine wheel in a .86 A/R. T2 flanged housing. a lot of nissans run this turbo (disco potato turbo) and push close to 300whp with very little lag. i think the tradeoff however is that by using such a small turbine/housing, is that there will be a lot of backpressure when you try and push that much whp.
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From: ME
Re: Spool and Lag (DIRep972)
DIRep- I know that each 'upsizing' of A/R and/or wheel will increase lag and increase top end power. I want to know the individual charistics each type of change. Is this to specific to make general comments about?
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Re: Spool and Lag (Bailhatch)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bailhatch »</TD></TR><TR><TD CLASS="quote">DIRep- I know that each 'upsizing' of A/R and/or wheel will increase lag and increase top end power. I want to know the individual charistics each type of change. Is this to specific to make general comments about?</TD></TR></TABLE>
Oh Ill try my best to explain that. well basically an upsizing in the exhaust a/r will make about 500'rpm's more lag, but it will also move your peak power band about 500rpm's higher in the rev range.. in general of course.... Going to a larger wheel does the same thing, but for the lag to power trade off... a larger wheel in a small housing is more favorable then a small wheel in a big housing.. hope that helps a little.
Oh Ill try my best to explain that. well basically an upsizing in the exhaust a/r will make about 500'rpm's more lag, but it will also move your peak power band about 500rpm's higher in the rev range.. in general of course.... Going to a larger wheel does the same thing, but for the lag to power trade off... a larger wheel in a small housing is more favorable then a small wheel in a big housing.. hope that helps a little.
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From: ME
Re: Spool and Lag (DIRep972)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DIRep972 »</TD></TR><TR><TD CLASS="quote">
a larger wheel in a small housing is more favorable then a small wheel in a big housing.. hope that helps a little.</TD></TR></TABLE>
This is exactly the relationship I want to know about. Does this apply to both side of the turbo? Can you explian why this is so. I haven't changed enough turbos myself to grasp this from experiance, thanks
a larger wheel in a small housing is more favorable then a small wheel in a big housing.. hope that helps a little.</TD></TR></TABLE>
This is exactly the relationship I want to know about. Does this apply to both side of the turbo? Can you explian why this is so. I haven't changed enough turbos myself to grasp this from experiance, thanks
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Re: Spool and Lag (Bailhatch)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bailhatch »</TD></TR><TR><TD CLASS="quote">
This is exactly the relationship I want to know about. Does this apply to both side of the turbo? Can you explian why this is so. I haven't changed enough turbos myself to grasp this from experiance, thanks</TD></TR></TABLE>
The compressor side is a lil different. When you start changing out wheels and housings you not only change the way it flows but you change where it is efficient too. Its probably best to find a compressor wheel/housing that work well together and/are efficient on ur set up and stick w/ it. If u want to try out new things id change stuff on the exhaust side first. Going to a larger turbine housing will reduce back pressure/increase flow but it won't really change how hard the compressor wheel/turbine wheel are working to produce boost. By keeping the housing small and going to a bigger turbine wheel you can still decrease the back pressure/increase the flow but now you also have more leaverage on the compressor wheel making its job easier too.
An example of how this works would be a stage 5 turbine wheel in a .63ar T3 housing. If you built the same turbo w/ a stage 3 turbine wheel and a .82ar T3 housing you would be increasing the flow but the lag would be worse.. The .63ar housing would have more velocity to spin up the stage 5 wheel. Also, another advantage is w/ the bigger turbine wheel you are able to support a larger compressor wheel which can in turn, help you make even more power.. This only gets you so far though, eventually you will get to the point where you are mismatching stuff; like if you did a stage 5 wheel in a .48ar housing.. The turbine wheel and compressor wheel would have so much potential but the .48ar housing would just choke all of that off.
hope some of that helps.
Modified by DIRep972 at 4:32 PM 12/31/2003
This is exactly the relationship I want to know about. Does this apply to both side of the turbo? Can you explian why this is so. I haven't changed enough turbos myself to grasp this from experiance, thanks</TD></TR></TABLE>
The compressor side is a lil different. When you start changing out wheels and housings you not only change the way it flows but you change where it is efficient too. Its probably best to find a compressor wheel/housing that work well together and/are efficient on ur set up and stick w/ it. If u want to try out new things id change stuff on the exhaust side first. Going to a larger turbine housing will reduce back pressure/increase flow but it won't really change how hard the compressor wheel/turbine wheel are working to produce boost. By keeping the housing small and going to a bigger turbine wheel you can still decrease the back pressure/increase the flow but now you also have more leaverage on the compressor wheel making its job easier too.
An example of how this works would be a stage 5 turbine wheel in a .63ar T3 housing. If you built the same turbo w/ a stage 3 turbine wheel and a .82ar T3 housing you would be increasing the flow but the lag would be worse.. The .63ar housing would have more velocity to spin up the stage 5 wheel. Also, another advantage is w/ the bigger turbine wheel you are able to support a larger compressor wheel which can in turn, help you make even more power.. This only gets you so far though, eventually you will get to the point where you are mismatching stuff; like if you did a stage 5 wheel in a .48ar housing.. The turbine wheel and compressor wheel would have so much potential but the .48ar housing would just choke all of that off.
hope some of that helps.
Modified by DIRep972 at 4:32 PM 12/31/2003
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