Gearing and All Motor... finding the perfect combination?
I have been struggling with finding the right gearing for my car.
My best passes a couple months ago were 11.2xx @ 123+. I was making 282whp @ 7800RPM at the time. I made two changes to the car. One was a cam change that put me over 303whp @ 8200RPM. The other change was going to a 25" slick.
Before the changes were made, I was passing through the traps at about 8600RPM which is where my peak power was dropping fast. Besides making more power as a solution, I chose to try a slightly taller slick. I thought this would help, but I think it actually hurt me.
Comparing the difference in tire size on the gear calculators I noticed that I had a higher top speed in each gear. I expected this. What I wasn't expecting was the length of time spent in those gears to increase as much as it did.
On the track, I seem to be stuck at 11.2xx, but I increased 1 MPH. I was also going through the traps at just about 8000RPM, which is now just below my peak HP. Watching my video playback of the passes and listening to the car, you can actually hear it bog into 4th.
My solution is to drop back down in tire size to the 24.5" slicks.
My question, is to those running 10's... do these finings seem on track? I don't know how much of a difference it makes, but all these passes are at 3100ft elevation, Last night was very hot and humid as well.
My best passes a couple months ago were 11.2xx @ 123+. I was making 282whp @ 7800RPM at the time. I made two changes to the car. One was a cam change that put me over 303whp @ 8200RPM. The other change was going to a 25" slick.
Before the changes were made, I was passing through the traps at about 8600RPM which is where my peak power was dropping fast. Besides making more power as a solution, I chose to try a slightly taller slick. I thought this would help, but I think it actually hurt me.
Comparing the difference in tire size on the gear calculators I noticed that I had a higher top speed in each gear. I expected this. What I wasn't expecting was the length of time spent in those gears to increase as much as it did.
On the track, I seem to be stuck at 11.2xx, but I increased 1 MPH. I was also going through the traps at just about 8000RPM, which is now just below my peak HP. Watching my video playback of the passes and listening to the car, you can actually hear it bog into 4th.
My solution is to drop back down in tire size to the 24.5" slicks.
My question, is to those running 10's... do these finings seem on track? I don't know how much of a difference it makes, but all these passes are at 3100ft elevation, Last night was very hot and humid as well.
You need to be shifting approx 500 rpm higher than your peak hp rpm. You made peak power at 8200 so you should be shifting at approx 8700. Simple.
Same stuff goes for finish line rpm. When you were going through the traps at 8600, you were doing great. Keep the crossing rpm at 8600 and above.
Also, stay with the shortest/lightest tire combo you can capably run.
This is my opinion.
Same stuff goes for finish line rpm. When you were going through the traps at 8600, you were doing great. Keep the crossing rpm at 8600 and above.
Also, stay with the shortest/lightest tire combo you can capably run.
This is my opinion.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by integrawow »</TD></TR><TR><TD CLASS="quote">You need to be shifting approx 500 rpm higher than your peak hp rpm. You made peak power at 8200 so you should be shifting at approx 8700. Simple.
Same stuff goes for finish line rpm. When you were going through the traps at 8600, you were doing great. Keep the crossing rpm at 8600 and above.
Also, stay with the shortest/lightest tire combo you can capably run.
This is my opinion.</TD></TR></TABLE>
Thankyou.
So since I now streched out my RPM range (peak power at 8200RPM), I might need to run an even smaller slick according to this theory?
Same stuff goes for finish line rpm. When you were going through the traps at 8600, you were doing great. Keep the crossing rpm at 8600 and above.
Also, stay with the shortest/lightest tire combo you can capably run.
This is my opinion.</TD></TR></TABLE>
Thankyou.
So since I now streched out my RPM range (peak power at 8200RPM), I might need to run an even smaller slick according to this theory?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2point6 »</TD></TR><TR><TD CLASS="quote">
Thankyou.
So since I now streched out my RPM range (peak power at 8200RPM), i might need to run an even smaller slick according to this theory?</TD></TR></TABLE>
The fact that you've raised your power band is quite interesting. My opinion is that not only will you want to go through the traps at 8600 or higher rpm, but since you've got a higher rpm power band engine combo, you'll need the extra gear (which is given by going with a shorter tire) down low to get you to your power band a little sooner, but hopefully without a loss of traction.
In other words, the shorter tire you mentioned should help you all around. Not only will you get the extra gear early in the run, but you'll also increase your finish line rpm. As long as the car is accelerating well down low, and crossing at the right rpm in the traps, you're good to go.
Thankyou.
So since I now streched out my RPM range (peak power at 8200RPM), i might need to run an even smaller slick according to this theory?</TD></TR></TABLE>
The fact that you've raised your power band is quite interesting. My opinion is that not only will you want to go through the traps at 8600 or higher rpm, but since you've got a higher rpm power band engine combo, you'll need the extra gear (which is given by going with a shorter tire) down low to get you to your power band a little sooner, but hopefully without a loss of traction.
In other words, the shorter tire you mentioned should help you all around. Not only will you get the extra gear early in the run, but you'll also increase your finish line rpm. As long as the car is accelerating well down low, and crossing at the right rpm in the traps, you're good to go.
its not so much as to shifting "500" higher. Its to shift at whatever RPM lands you at the best torque and maintains momentum as much as possible while going into the next gear.
Here is my input on the subject.
While gear ratios are important , i believe they are the LAST thing that should be messed with . As long as you are starting with a decent trans ( ie: not an ls, h23, etc).
The 2 major things are tire size and Final drives.
In my opinion You should drop back down to the 24.5. I know all the Higher hp all motor cars around here use that size. Some making 320-340hp and are fine.
What was the reasoning to swap to the 25s? What were your 60fts like ?
There is no magical Number in how many rpms above the rpm in which max power is achieved, that you should shift. You need wheels speed plain and simple.
Even if power is made at 7600 ( for example) you still need to shift close to redline in order to gain enough wheel speed , just because power is falling doesnt mean the car will stay at the same mph. This will also help with rpm drop going into next gear.
Drop back down to the 24.5s and if you feel you need to change the rpm you are crossing the line at , then change the Final drive accordingly. What are you using now for FD ?
While gear ratios are important , i believe they are the LAST thing that should be messed with . As long as you are starting with a decent trans ( ie: not an ls, h23, etc).
The 2 major things are tire size and Final drives.
In my opinion You should drop back down to the 24.5. I know all the Higher hp all motor cars around here use that size. Some making 320-340hp and are fine.
What was the reasoning to swap to the 25s? What were your 60fts like ?
There is no magical Number in how many rpms above the rpm in which max power is achieved, that you should shift. You need wheels speed plain and simple.
Even if power is made at 7600 ( for example) you still need to shift close to redline in order to gain enough wheel speed , just because power is falling doesnt mean the car will stay at the same mph. This will also help with rpm drop going into next gear.
Drop back down to the 24.5s and if you feel you need to change the rpm you are crossing the line at , then change the Final drive accordingly. What are you using now for FD ?
Trending Topics
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2fastGSR »</TD></TR><TR><TD CLASS="quote">Here is my input on the subject.
While gear ratios are important , i believe they are the LAST thing that should be messed with . As long as you are starting with a decent trans ( ie: not an ls, h23, etc).
The 2 major things are tire size and Final drives.
In my opinion You should drop back down to the 24.5. I know all the Higher hp all motor cars around here use that size. Some making 320-340hp and are fine.
What was the reasoning to swap to the 25s? What were your 60fts like ?
There is no magical Number in how many rpms above the rpm in which max power is achieved, that you should shift. You need wheels speed plain and simple.
Even if power is made at 7600 ( for example) you still need to shift close to redline in order to gain enough wheel speed , just because power is falling doesnt mean the car will stay at the same mph. This will also help with rpm drop going into next gear.
Drop back down to the 24.5s and if you feel you need to change the rpm you are crossing the line at , then change the Final drive accordingly. What are you using now for FD ?
</TD></TR></TABLE>
Hey Jake,
My reasoning was that I was dropping way off in power when I went through the traps at 8600RPM. This was when my car was making peak HP at 7800RPM. I was always under the impression that you wanted to get as close to peak HP when hitting the traps. I also was fighting wheelspin off the line, so my thinking was to promote better traction off the line and gain a little more top end to place my RPMs closer to peak HP.
Before the slick change I was pulling consistant 1.51- 1.52 60fts. Video of the car showed lots of wheelspin, so we thought the larger slick would help this.
The only 3 passes I made on the larger slicks were in the mid 1.55+ 60ft. No real conclusion there... but I did feel the car bog into the longer gears and on the video you can hear it as well. I Just don't make the power to turn them.
Currently, I am running a MFactory 4.64 FD with my Euro R Trans. Looking at the gear calcs, it looks like I could change to a Circuitworx 4.71 FD and keep the 25" slicks if I need. The problem is that I havent quite figured out gearing changes vs. FD changes and how they affect the car.
While gear ratios are important , i believe they are the LAST thing that should be messed with . As long as you are starting with a decent trans ( ie: not an ls, h23, etc).
The 2 major things are tire size and Final drives.
In my opinion You should drop back down to the 24.5. I know all the Higher hp all motor cars around here use that size. Some making 320-340hp and are fine.
What was the reasoning to swap to the 25s? What were your 60fts like ?
There is no magical Number in how many rpms above the rpm in which max power is achieved, that you should shift. You need wheels speed plain and simple.
Even if power is made at 7600 ( for example) you still need to shift close to redline in order to gain enough wheel speed , just because power is falling doesnt mean the car will stay at the same mph. This will also help with rpm drop going into next gear.
Drop back down to the 24.5s and if you feel you need to change the rpm you are crossing the line at , then change the Final drive accordingly. What are you using now for FD ?
</TD></TR></TABLE>
Hey Jake,
My reasoning was that I was dropping way off in power when I went through the traps at 8600RPM. This was when my car was making peak HP at 7800RPM. I was always under the impression that you wanted to get as close to peak HP when hitting the traps. I also was fighting wheelspin off the line, so my thinking was to promote better traction off the line and gain a little more top end to place my RPMs closer to peak HP.
Before the slick change I was pulling consistant 1.51- 1.52 60fts. Video of the car showed lots of wheelspin, so we thought the larger slick would help this.
The only 3 passes I made on the larger slicks were in the mid 1.55+ 60ft. No real conclusion there... but I did feel the car bog into the longer gears and on the video you can hear it as well. I Just don't make the power to turn them.
Currently, I am running a MFactory 4.64 FD with my Euro R Trans. Looking at the gear calcs, it looks like I could change to a Circuitworx 4.71 FD and keep the 25" slicks if I need. The problem is that I havent quite figured out gearing changes vs. FD changes and how they affect the car.
now the lower 1.5 60fts were also with less power right?
I still think the 24.5s would be better, just maybe lower the shift point so that you arent crossing the traps so high out of your power range.
If peak power is now 8200 , then crossing the traps @ 86-8700 really isnt that bad. Its actually pretty good.
What EMS are you using? Does it have a feature where you can take timing away until a certain wheelspeed ? basically not launching on full power to avoid wheelspin ? That would allow you to use the smaller tire and not "blow the doors off " the tires.
I would still go back to the 24.5s and change FDs if they dont work to your liking. There should be no reason you cant cut those same low 1.5s again
I still think the 24.5s would be better, just maybe lower the shift point so that you arent crossing the traps so high out of your power range.
If peak power is now 8200 , then crossing the traps @ 86-8700 really isnt that bad. Its actually pretty good.
What EMS are you using? Does it have a feature where you can take timing away until a certain wheelspeed ? basically not launching on full power to avoid wheelspin ? That would allow you to use the smaller tire and not "blow the doors off " the tires.
I would still go back to the 24.5s and change FDs if they dont work to your liking. There should be no reason you cant cut those same low 1.5s again
i was looking at your dyno graph.. your power is still strong at 8800 rpms.
get back on the dyno and pull the car till the power starts to die.
if i had to guess id say shift around 9800 rpms..
if you dont want to get back on the dyno you can do what i did, i increased my shift light by 200 rpms every pass till the car didnt get any faster.
people are going low 9's on a 24.5 inch tire revin to 10000 rpms, you should be able to hook w/that tire as well.
get back on the dyno and pull the car till the power starts to die.
if i had to guess id say shift around 9800 rpms..
if you dont want to get back on the dyno you can do what i did, i increased my shift light by 200 rpms every pass till the car didnt get any faster.
people are going low 9's on a 24.5 inch tire revin to 10000 rpms, you should be able to hook w/that tire as well.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg »</TD></TR><TR><TD CLASS="quote">if you dont want to get back on the dyno you can do what i did, i increased my shift light by 200 rpms every pass till the car didnt get any faster.
</TD></TR></TABLE>
I like that idea. . .
Although I am not too keen on the idea of shifting the motor at 9800 haha
</TD></TR></TABLE>
I like that idea. . .
Although I am not too keen on the idea of shifting the motor at 9800 haha
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2fastGSR »</TD></TR><TR><TD CLASS="quote">now the lower 1.5 60fts were also with less power right?
I still think the 24.5s would be better, just maybe lower the shift point so that you arent crossing the traps so high out of your power range.
If peak power is now 8200 , then crossing the traps @ 86-8700 really isnt that bad. Its actually pretty good.
What EMS are you using? Does it have a feature where you can take timing away until a certain wheelspeed ? basically not launching on full power to avoid wheelspin ? That would allow you to use the smaller tire and not "blow the doors off " the tires.
I would still go back to the 24.5s and change FDs if they dont work to your liking. There should be no reason you cant cut those same low 1.5s again </TD></TR></TABLE>
Yes, the lower 60ft times were run with less power, however I only made 3 passes on the larger slicks with changes to air pressure only. I was around 8psi when I made my best 60ft of 1.55 for the night. It started raining, so I couldn't drop the slicks to see if that helped out any.
The EMS is Hondata S300, so yes I can remove timing based on gear. once I get where I need through the traps, I plan on dialing the launch in further. We are also going to add a wheelie bar to the mix soon, so we will see what happens then.
Back to the 24.5"... it really amazing what a half inch will get you.
I still think the 24.5s would be better, just maybe lower the shift point so that you arent crossing the traps so high out of your power range.
If peak power is now 8200 , then crossing the traps @ 86-8700 really isnt that bad. Its actually pretty good.
What EMS are you using? Does it have a feature where you can take timing away until a certain wheelspeed ? basically not launching on full power to avoid wheelspin ? That would allow you to use the smaller tire and not "blow the doors off " the tires.
I would still go back to the 24.5s and change FDs if they dont work to your liking. There should be no reason you cant cut those same low 1.5s again </TD></TR></TABLE>
Yes, the lower 60ft times were run with less power, however I only made 3 passes on the larger slicks with changes to air pressure only. I was around 8psi when I made my best 60ft of 1.55 for the night. It started raining, so I couldn't drop the slicks to see if that helped out any.
The EMS is Hondata S300, so yes I can remove timing based on gear. once I get where I need through the traps, I plan on dialing the launch in further. We are also going to add a wheelie bar to the mix soon, so we will see what happens then.
Back to the 24.5"... it really amazing what a half inch will get you.
no need in pulling timing... work on the chassis/suspension. you havent broken any drivetrain parts... that means you arent hooking very well
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg »</TD></TR><TR><TD CLASS="quote">no need in pulling timing... work on the chassis/suspension. you havent broken any drivetrain parts... that means you arent hooking very well
</TD></TR></TABLE>
Unless you are meaning something beyond axles, I have broken a DSS 5.9 passenger side axle twice now.
</TD></TR></TABLE>Unless you are meaning something beyond axles, I have broken a DSS 5.9 passenger side axle twice now.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg »</TD></TR><TR><TD CLASS="quote">i was looking at your dyno graph.. your power is still strong at 8800 rpms.
get back on the dyno and pull the car till the power starts to die.
if i had to guess id say shift around 9800 rpms..
if you dont want to get back on the dyno you can do what i did, i increased my shift light by 200 rpms every pass till the car didnt get any faster.
people are going low 9's on a 24.5 inch tire revin to 10000 rpms, you should be able to hook w/that tire as well.</TD></TR></TABLE>
I am not sure what the spike in power after 8500RPM is, but you can see that power started falling off at 8200RPM. I will have to talk to Joe at Locash about this.
get back on the dyno and pull the car till the power starts to die.
if i had to guess id say shift around 9800 rpms..
if you dont want to get back on the dyno you can do what i did, i increased my shift light by 200 rpms every pass till the car didnt get any faster.
people are going low 9's on a 24.5 inch tire revin to 10000 rpms, you should be able to hook w/that tire as well.</TD></TR></TABLE>
I am not sure what the spike in power after 8500RPM is, but you can see that power started falling off at 8200RPM. I will have to talk to Joe at Locash about this.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2point6 »</TD></TR><TR><TD CLASS="quote">
Unless you are meaning something beyond axles, I have broken a DSS 5.9 passenger side axle twice now.</TD></TR></TABLE>
you must have something not quite right, most of the time the 1/2shaft will break before the dss 5.9 axles will.
check your compliance and lca bushings.
what clutch do you have?
Unless you are meaning something beyond axles, I have broken a DSS 5.9 passenger side axle twice now.</TD></TR></TABLE>
you must have something not quite right, most of the time the 1/2shaft will break before the dss 5.9 axles will.
check your compliance and lca bushings.
what clutch do you have?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg »</TD></TR><TR><TD CLASS="quote">
you must have something not quite right, most of the time the 1/2shaft will break before the dss 5.9 axles will.
check your compliance and lca bushings.
what clutch do you have?</TD></TR></TABLE>
We have already looked into the LCAs moving. The bushings are good. They are Omnipower LCAs. There is no play with the traction bar either. The clutch we are using is a competition clutch twin disk.
you must have something not quite right, most of the time the 1/2shaft will break before the dss 5.9 axles will.
check your compliance and lca bushings.
what clutch do you have?</TD></TR></TABLE>
We have already looked into the LCAs moving. The bushings are good. They are Omnipower LCAs. There is no play with the traction bar either. The clutch we are using is a competition clutch twin disk.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg »</TD></TR><TR><TD CLASS="quote">no need in pulling timing... work on the chassis/suspension. you havent broken any drivetrain parts... that means you arent hooking very well
</TD></TR></TABLE>
Not necessarily true.
Can most cars get decent 60fts fine tuning chassis/suspension? Yes
However, there are quite a few all motor street cars making higher Hp, ie: 310+ that use the ems to pull timing until a certain wheel speed ( thus not launching on full hp) and it works very well for them . . .
</TD></TR></TABLE>Not necessarily true.
Can most cars get decent 60fts fine tuning chassis/suspension? Yes
However, there are quite a few all motor street cars making higher Hp, ie: 310+ that use the ems to pull timing until a certain wheel speed ( thus not launching on full hp) and it works very well for them . . .
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2fastGSR »</TD></TR><TR><TD CLASS="quote">
Not necessarily true.
Can most cars get decent 60fts fine tuning chassis/suspension? Yes
However, there are quite a few all motor street cars making higher Hp, ie: 310+ that use the ems to pull timing until a certain wheel speed ( thus not launching on full hp) and it works very well for them . . . </TD></TR></TABLE>
this is where data logging is your best friend!
IMO.... track tuning is key.... its not all about power in "real world" situations ie. the drag stip
Not necessarily true.
Can most cars get decent 60fts fine tuning chassis/suspension? Yes
However, there are quite a few all motor street cars making higher Hp, ie: 310+ that use the ems to pull timing until a certain wheel speed ( thus not launching on full hp) and it works very well for them . . . </TD></TR></TABLE>
this is where data logging is your best friend!
IMO.... track tuning is key.... its not all about power in "real world" situations ie. the drag stip
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2point6 »</TD></TR><TR><TD CLASS="quote">
We have already looked into the LCAs moving. The bushings are good. They are Omnipower LCAs. There is no play with the traction bar either. The clutch we are using is a competition clutch twin disk.</TD></TR></TABLE>
try a carbon clutch, the CC twins are very harsh.. the carbon clutches have a little give which helps with breaking stuff as well as traction.
We have already looked into the LCAs moving. The bushings are good. They are Omnipower LCAs. There is no play with the traction bar either. The clutch we are using is a competition clutch twin disk.</TD></TR></TABLE>
try a carbon clutch, the CC twins are very harsh.. the carbon clutches have a little give which helps with breaking stuff as well as traction.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg »</TD></TR><TR><TD CLASS="quote">
try a carbon clutch, the CC twins are very harsh.. the carbon clutches have a little give which helps with breaking stuff as well as traction.
</TD></TR></TABLE>
What manufacturer do you recomend and how much do they run?
try a carbon clutch, the CC twins are very harsh.. the carbon clutches have a little give which helps with breaking stuff as well as traction.
</TD></TR></TABLE>
What manufacturer do you recomend and how much do they run?
i have only delt w/tilton and quartermaster... both are good, easy to get parts for etc... its been so long since i have priced one i have no idea what they cost.



