Need help - gears, stall in FI street car
08-24-2016, 01:29 AM
#1
Pro
Thread Starter
Need help - gears, stall in FI street car
Not getting many replies - one very good one but would like more opinions. Got to be many street cars running the occasional 1/8th. Need assistance with gear and stall. please read - thanks.
I've done the research and read it all. Lots of disagreement about parts as usual. So, I wanted to post here were I can find some FI street car/drag racers who have been through the various combinations.
I'm getting ready to do the standard new to FI build. C5, stock bottom LS1, lightly ported LS6 heads with dual springs, Long tubes, cat-less, built A4, Paxton 1500 limited to max of 10 PSI, meth, small blower cam - no larger than 224/228 - 114 +4. Won't turn the car much past 6200 - 6300 RPM for engine longevity sake.This is a 90% street car with occasional 1/8 mile drag run for grudge or fun. Will run not more sticky than 17" drag radials (26 - 27" tall) - no slicks. I've got most of this ironed out in my mind except for a couple of variables. I will keep the fly wheel horsepower in the 600 - 650 range because I don't want to blow and I don't want to forge bottom end.
1. Rear gear. I currently have a 2.73 rear.I n my early years of small blocks and shoe box Chevy's I found the sweet spot on street rears to be a 3.70. Could still cruse, decent mileage and fairly good get up and go when ambushed on the street. However, now that I'm looking at the above setup in a C5 things may be different. I don't want a gear to take away all the good mileage, good cruse and I don't want to be just changing into third just before the lights in an 1/8th. I think I'm in 3.42 or 3.73 territory??? This rear ratio variable ties in with item #2, below.
2. I need to choose a stall speed. Considering I'm only gonna be on drag radials at best and with a high torque cam I am afraid a high stall speed will result in nothing but blowing off the tires - especially if I should happen to accidentally encounter a city street type surface
. I want to match the stall with the rear and the power level. I read a lot of posts that say you need a 3600 stall but I just can't see that with limited traction and torque cam. Plus I'm in an area with a lot of mountain driving opportunities (went to the Dragon last year where 430 vettes set a record, bumper to bumper on that run - going again this September). Don't want a loose converter screwing up my fun on the twistiest (what limited fun you can have with a A4 on twistiest anyway).
I know there is no perfect combination but you guys with street cars combined with 1/8th mile experience can probably save me from making major and expensive mistakes.
At present I am leaning toward a 3.46 with a 2800 stall. Any advise would be appreciated. Remember - street car with occasional 1/8th mile duty. Sorry to be so long winded but wanted to thoroughly explain.
I've done the research and read it all. Lots of disagreement about parts as usual. So, I wanted to post here were I can find some FI street car/drag racers who have been through the various combinations.
I'm getting ready to do the standard new to FI build. C5, stock bottom LS1, lightly ported LS6 heads with dual springs, Long tubes, cat-less, built A4, Paxton 1500 limited to max of 10 PSI, meth, small blower cam - no larger than 224/228 - 114 +4. Won't turn the car much past 6200 - 6300 RPM for engine longevity sake.This is a 90% street car with occasional 1/8 mile drag run for grudge or fun. Will run not more sticky than 17" drag radials (26 - 27" tall) - no slicks. I've got most of this ironed out in my mind except for a couple of variables. I will keep the fly wheel horsepower in the 600 - 650 range because I don't want to blow and I don't want to forge bottom end.
1. Rear gear. I currently have a 2.73 rear.I n my early years of small blocks and shoe box Chevy's I found the sweet spot on street rears to be a 3.70. Could still cruse, decent mileage and fairly good get up and go when ambushed on the street. However, now that I'm looking at the above setup in a C5 things may be different. I don't want a gear to take away all the good mileage, good cruse and I don't want to be just changing into third just before the lights in an 1/8th. I think I'm in 3.42 or 3.73 territory??? This rear ratio variable ties in with item #2, below.
2. I need to choose a stall speed. Considering I'm only gonna be on drag radials at best and with a high torque cam I am afraid a high stall speed will result in nothing but blowing off the tires - especially if I should happen to accidentally encounter a city street type surface
. I want to match the stall with the rear and the power level. I read a lot of posts that say you need a 3600 stall but I just can't see that with limited traction and torque cam. Plus I'm in an area with a lot of mountain driving opportunities (went to the Dragon last year where 430 vettes set a record, bumper to bumper on that run - going again this September). Don't want a loose converter screwing up my fun on the twistiest (what limited fun you can have with a A4 on twistiest anyway).I know there is no perfect combination but you guys with street cars combined with 1/8th mile experience can probably save me from making major and expensive mistakes.
At present I am leaning toward a 3.46 with a 2800 stall. Any advise would be appreciated. Remember - street car with occasional 1/8th mile duty. Sorry to be so long winded but wanted to thoroughly explain.
Last edited by BURL; 08-29-2016 at 04:18 PM. Reason: word omission
08-24-2016, 03:51 AM
#2
Le Mans Master
3.42 & 27-28" tires.
Get a custom converter from any of the good converter vendors, lots of us here use FTI. For more street/roll racing, I'd lean to the tighter side...Mainly for traction purposes and more mph going down the track. At a minimum, I'd get something that flashes to about 3500 ish. (flash speed, not foot brake stall). IF you know you're gonna be roll racing a lot, I'd get a triple disc converter so you can lock it WOT to gain you some mph.
You should have no problem getting into the high 9s, bottom 10s with your current plan(650 rwhp) with the right converter. Make sure to use a good transcooler also... A lot of us use the B&M 70297 with the fan, it works great with loose converters.
Get a custom converter from any of the good converter vendors, lots of us here use FTI. For more street/roll racing, I'd lean to the tighter side...Mainly for traction purposes and more mph going down the track. At a minimum, I'd get something that flashes to about 3500 ish. (flash speed, not foot brake stall). IF you know you're gonna be roll racing a lot, I'd get a triple disc converter so you can lock it WOT to gain you some mph.
You should have no problem getting into the high 9s, bottom 10s with your current plan(650 rwhp) with the right converter. Make sure to use a good transcooler also... A lot of us use the B&M 70297 with the fan, it works great with loose converters.
Last edited by ajrothm; 08-24-2016 at 03:58 AM.
08-24-2016, 11:54 PM
#3
Pro
Thread Starter
Need help - gears, stall in FI street car
3.42 & 27-28" tires.
Get a custom converter from any of the good converter vendors, lots of us here use FTI. For more street/roll racing, I'd lean to the tighter side...Mainly for traction purposes and more mph going down the track. At a minimum, I'd get something that flashes to about 3500 ish. (flash speed, not foot brake stall). IF you know you're gonna be roll racing a lot, I'd get a triple disc converter so you can lock it WOT to gain you some mph.
You should have no problem getting into the high 9s, bottom 10s with your current plan(650 rwhp) with the right converter. Make sure to use a good transcooler also... A lot of us use the B&M 70297 with the fan, it works great with loose converters.
Get a custom converter from any of the good converter vendors, lots of us here use FTI. For more street/roll racing, I'd lean to the tighter side...Mainly for traction purposes and more mph going down the track. At a minimum, I'd get something that flashes to about 3500 ish. (flash speed, not foot brake stall). IF you know you're gonna be roll racing a lot, I'd get a triple disc converter so you can lock it WOT to gain you some mph.
You should have no problem getting into the high 9s, bottom 10s with your current plan(650 rwhp) with the right converter. Make sure to use a good transcooler also... A lot of us use the B&M 70297 with the fan, it works great with loose converters.
08-25-2016, 04:39 AM
#4
Le Mans Master
Ok first off, you don't want too much gear with a blower car and an auto.... So 3.42 max. Preferably at least a 26.5" tire...
As for the flywheel HP, how the hell are you going to guess-ta-mate that? Stick with the universal language in late model performance and tuning, RWHP.. On even the most mild setup, you'll make 550rwhp thru a locked auto. Enough for high 10s in the 1/4, or high 6.70-6.80s in the 1/8.
For lots of twistie driving, keep the converter tight....once again, call FTI, explain the intended use, estimated HP, and weight. Odds are, you'll end up with something that flashes to about 3200...(not a "3200 stall" like your old school cars use to use, real converters are not rated with a stall rating). Odds are, you'll end up with a tight 9.5". *If you are more concerned with roll racing and twisties, you may as well just stick with the stock converter. You are trying to compromise for multiple scenarios so....gotta pick what's most important. Personally, I'd get a custom converter, tell em to keep it on the tight side.
As for your shifts, you are likely going to finish the 1/8 around 100mph in 2nd, especially if you run on a 28" tire. If you want to force a 2-3 shift before the the 1/8, you could try the 275/40/17 Hoosier DR.. It's short, light and hooks hard.
As for twisties, you won't be using any kind of drag radial for that, period. Your best bet is the Toyo R888. Good all around tire for decent hook and great for twisties. It is a heavy tire tho...and expensive.
As for the flywheel HP, how the hell are you going to guess-ta-mate that? Stick with the universal language in late model performance and tuning, RWHP.. On even the most mild setup, you'll make 550rwhp thru a locked auto. Enough for high 10s in the 1/4, or high 6.70-6.80s in the 1/8.
For lots of twistie driving, keep the converter tight....once again, call FTI, explain the intended use, estimated HP, and weight. Odds are, you'll end up with something that flashes to about 3200...(not a "3200 stall" like your old school cars use to use, real converters are not rated with a stall rating). Odds are, you'll end up with a tight 9.5". *If you are more concerned with roll racing and twisties, you may as well just stick with the stock converter. You are trying to compromise for multiple scenarios so....gotta pick what's most important. Personally, I'd get a custom converter, tell em to keep it on the tight side.
As for your shifts, you are likely going to finish the 1/8 around 100mph in 2nd, especially if you run on a 28" tire. If you want to force a 2-3 shift before the the 1/8, you could try the 275/40/17 Hoosier DR.. It's short, light and hooks hard.
As for twisties, you won't be using any kind of drag radial for that, period. Your best bet is the Toyo R888. Good all around tire for decent hook and great for twisties. It is a heavy tire tho...and expensive.
08-25-2016, 03:32 PM
#5
Pro
Thread Starter
Need a little more help - gears, stall in FI street car
Ok first off, you don't want too much gear with a blower car and an auto.... So 3.42 max. Preferably at least a 26.5" tire...
As for the flywheel HP, how the hell are you going to guess-ta-mate that? Stick with the universal language in late model performance and tuning, RWHP.. On even the most mild setup, you'll make 550rwhp thru a locked auto. Enough for high 10s in the 1/4, or high 6.70-6.80s in the 1/8.
For lots of twistie driving, keep the converter tight....once again, call FTI, explain the intended use, estimated HP, and weight. Odds are, you'll end up with something that flashes to about 3200...(not a "3200 stall" like your old school cars use to use, real converters are not rated with a stall rating). Odds are, you'll end up with a tight 9.5". *If you are more concerned with roll racing and twisties, you may as well just stick with the stock converter. You are trying to compromise for multiple scenarios so....gotta pick what's most important. Personally, I'd get a custom converter, tell em to keep it on the tight side.
As for your shifts, you are likely going to finish the 1/8 around 100mph in 2nd, especially if you run on a 28" tire. If you want to force a 2-3 shift before the the 1/8, you could try the 275/40/17 Hoosier DR.. It's short, light and hooks hard.
As for twisties, you won't be using any kind of drag radial for that, period. Your best bet is the Toyo R888. Good all around tire for decent hook and great for twisties. It is a heavy tire tho...and expensive.
As for the flywheel HP, how the hell are you going to guess-ta-mate that? Stick with the universal language in late model performance and tuning, RWHP.. On even the most mild setup, you'll make 550rwhp thru a locked auto. Enough for high 10s in the 1/4, or high 6.70-6.80s in the 1/8.
For lots of twistie driving, keep the converter tight....once again, call FTI, explain the intended use, estimated HP, and weight. Odds are, you'll end up with something that flashes to about 3200...(not a "3200 stall" like your old school cars use to use, real converters are not rated with a stall rating). Odds are, you'll end up with a tight 9.5". *If you are more concerned with roll racing and twisties, you may as well just stick with the stock converter. You are trying to compromise for multiple scenarios so....gotta pick what's most important. Personally, I'd get a custom converter, tell em to keep it on the tight side.
As for your shifts, you are likely going to finish the 1/8 around 100mph in 2nd, especially if you run on a 28" tire. If you want to force a 2-3 shift before the the 1/8, you could try the 275/40/17 Hoosier DR.. It's short, light and hooks hard.
As for twisties, you won't be using any kind of drag radial for that, period. Your best bet is the Toyo R888. Good all around tire for decent hook and great for twisties. It is a heavy tire tho...and expensive.
Let me follow up by adding a little info about my intentions and confirming that I understand what you are saying.
Additional build info:
1. 17" Drag radials are intended only for strip (or Saturday night
). Will be between 26 - 27 inches. Road and twisty driving will be on high performance street tires 17" front, 18" rear. I live in a twisties opportunity area but only do it occasionally - mostly standard street stuff so twisties performance is somewhat desired but also secondary to standard stuff. Will do limited roll racing and no road course. So, focus will to be on street cruising, 1/8th drag and occasional roll race.2. I'm an old fart so I remember stalled converts performing like when we put Chevy Vega converters behind 454 big blocks! I've read enough
on the modern stuff to realize they are a different animals and as you suggest, I intend to call the converter company for suggestions. But i needed some experienced advise before I talk to them as I called one major company about 2-3 months ago and they suggested a 4000 RPM stall after I sent them my build info and proposed usage
. So when I call this time I needed some experienced advise so I can better talk with them and make good decision. I now have that from you.3. I think I need to nail my rear ratio before calling converter people. I don't think I want to force a second to third shift in the 1/8th. Adding another shift from 2nd to 3rd and dropping RPM just at the line would seem to be less efficient. You say a 3.42 max. Since I am limiting to 6200 RPM does this mean in my power range with A4 tranny and a 17" 26 - 27" tire that a 3.15 is a valid consideration to avoid a 2-3rd gear shift? I'm sure the 3.15 would give better cruising and mileage but don't want to under gear the car. Ideally I would like to cross the line at about 6200 in second.
I would appreciate any additional advise you have. I have seen that you make many replies on the forum and give good advise. I was hoping someone with close to my build that has a lot of experience with 1/8th mile and street driving combo's would chime in. But, guess my posts are too long as I don't get a lot of replies to questions.
Thanks in advance for any additional comments.
08-29-2016, 04:16 PM
#6
Pro
Thread Starter
Need more opinions
Not getting many replies - one very good one but would like more opinions. Got to many street cars running the occasional 1/8th. Need assistance with gear and stall. please read - thanks.
I've done the research and read it all. Lots of disagreement about parts as usual. So, I wanted to post here were I can find some FI street car/drag racers who have been through the various combinations.
I'm getting ready to do the standard new to FI build. C5, stock bottom LS1, lightly ported LS6 heads with dual springs, Long tubes, cat-less, built A4, Paxton 1500 limited to max of 10 PSI, meth, small blower cam - no larger than 224/228 - 114 +4. Won't turn the car much past 6200 - 6300 RPM for engine longevity sake.This is a 90% street car with occasional 1/8 mile drag run for grudge or fun. Will run not more sticky than 17" drag radials (26 - 27" tall) - no slicks. I've got most of this ironed out in my mind except for a couple of variables. I will keep the fly wheel horsepower in the 600 - 650 range because I don't want to blow and I don't want to forge bottom end.
1. Rear gear. I currently have a 2.73 rear.I n my early years of small blocks and shoe box Chevy's I found the sweet spot on street rears to be a 3.70. Could still cruse, decent mileage and fairly good get up and go when ambushed on the street. However, now that I'm looking at the above setup in a C5 things may be different. I don't want a gear to take away all the good mileage, good cruse and I don't want to be just changing into third just before the lights in an 1/8th. I think I'm in 3.42 or 3.73 territory??? This rear ratio variable ties in with item #2, below.
2. I need to choose a stall speed. Considering I'm only gonna be on drag radials at best and with a high torque cam I am afraid a high stall speed will result in nothing but blowing off the tires - especially if I should happen to accidentally encounter a city street type surface. I want to match the stall with the rear and the power level. I read a lot of posts that say you need a 3600 stall but I just can't see that with limited traction and torque cam. Plus I'm in an area with a lot of mountain driving opportunities (went to the Dragon last year where 430 vettes set a record, bumper to bumper on that run - going again this September). Don't want a loose converter screwing up my fun on the twistiest (what limited fun you can have with a A4 on twistiest anyway).
I know there is no perfect combination but you guys with street cars combined with 1/8th mile experience can probably save me from making major and expensive mistakes.
At present I am leaning toward a 3.46 with a 2800 stall. Any advise would be appreciated. Remember - street car with occasional 1/8th mile duty. Sorry to be so long winded but wanted to thoroughly explain.
I've done the research and read it all. Lots of disagreement about parts as usual. So, I wanted to post here were I can find some FI street car/drag racers who have been through the various combinations.
I'm getting ready to do the standard new to FI build. C5, stock bottom LS1, lightly ported LS6 heads with dual springs, Long tubes, cat-less, built A4, Paxton 1500 limited to max of 10 PSI, meth, small blower cam - no larger than 224/228 - 114 +4. Won't turn the car much past 6200 - 6300 RPM for engine longevity sake.This is a 90% street car with occasional 1/8 mile drag run for grudge or fun. Will run not more sticky than 17" drag radials (26 - 27" tall) - no slicks. I've got most of this ironed out in my mind except for a couple of variables. I will keep the fly wheel horsepower in the 600 - 650 range because I don't want to blow and I don't want to forge bottom end.
1. Rear gear. I currently have a 2.73 rear.I n my early years of small blocks and shoe box Chevy's I found the sweet spot on street rears to be a 3.70. Could still cruse, decent mileage and fairly good get up and go when ambushed on the street. However, now that I'm looking at the above setup in a C5 things may be different. I don't want a gear to take away all the good mileage, good cruse and I don't want to be just changing into third just before the lights in an 1/8th. I think I'm in 3.42 or 3.73 territory??? This rear ratio variable ties in with item #2, below.
2. I need to choose a stall speed. Considering I'm only gonna be on drag radials at best and with a high torque cam I am afraid a high stall speed will result in nothing but blowing off the tires - especially if I should happen to accidentally encounter a city street type surface
. I want to match the stall with the rear and the power level. I read a lot of posts that say you need a 3600 stall but I just can't see that with limited traction and torque cam. Plus I'm in an area with a lot of mountain driving opportunities (went to the Dragon last year where 430 vettes set a record, bumper to bumper on that run - going again this September). Don't want a loose converter screwing up my fun on the twistiest (what limited fun you can have with a A4 on twistiest anyway).I know there is no perfect combination but you guys with street cars combined with 1/8th mile experience can probably save me from making major and expensive mistakes.
At present I am leaning toward a 3.46 with a 2800 stall. Any advise would be appreciated. Remember - street car with occasional 1/8th mile duty. Sorry to be so long winded but wanted to thoroughly explain.