Converter Quandary
Converter Quandary Hello gents,
So I'm in a bit of pickle here and trying to figure out which direction to go or what my options are.
Car is a 1999 Camaro SS, H-Beam Rod/ Forged Piston 5.7, ported 317's, cam, Billet S484, TH475, Ford 9" w/ 3.50 gear and 275/60/15 tire.
I bought the car with a Circle D Pro Series 245mm converter which is rated to upwards of 800hp, the guys at Circle D said they regularly see this converter work with combinations over 800hp.
My current combination has the rpm drop between shifts dropping as I've added boost and based on this, I will have reached the limits of this converter by 16lbs. of boost as my shifts will be in the 600-700rpm drop range.
This was shifting at 6,600rpm, I've been targeting 7,000rpm but have the habit of being early lol.
Circle D is telling me they can restall the converter to accommodate more boost but at the lower boost levels (14-16lbs.) the spool will be slower, and the shift drop could bring the rpm band back down into peak torque taxing the rods.
Trying to figure out what to do here, the car is a streetcar and will spend the majority of its life in pump gas mode at 14-16lbs. and see higher boost for hero track/dyno days.
Is there a converter that will bridge this gap?
Should I raise my shift points higher?
Will the spool really be affected that much? (It spools really quickly now)
Could I just dump some timing at peak torque to protect the rods?
Would love some input from guys who have been here and what their solution was.
Thanks!
So I'm in a bit of pickle here and trying to figure out which direction to go or what my options are.
Car is a 1999 Camaro SS, H-Beam Rod/ Forged Piston 5.7, ported 317's, cam, Billet S484, TH475, Ford 9" w/ 3.50 gear and 275/60/15 tire.
I bought the car with a Circle D Pro Series 245mm converter which is rated to upwards of 800hp, the guys at Circle D said they regularly see this converter work with combinations over 800hp.
My current combination has the rpm drop between shifts dropping as I've added boost and based on this, I will have reached the limits of this converter by 16lbs. of boost as my shifts will be in the 600-700rpm drop range.
This was shifting at 6,600rpm, I've been targeting 7,000rpm but have the habit of being early lol.
Circle D is telling me they can restall the converter to accommodate more boost but at the lower boost levels (14-16lbs.) the spool will be slower, and the shift drop could bring the rpm band back down into peak torque taxing the rods.
Trying to figure out what to do here, the car is a streetcar and will spend the majority of its life in pump gas mode at 14-16lbs. and see higher boost for hero track/dyno days.
Is there a converter that will bridge this gap?
Should I raise my shift points higher?
Will the spool really be affected that much? (It spools really quickly now)
Could I just dump some timing at peak torque to protect the rods?
Would love some input from guys who have been here and what their solution was.
Thanks!
You're using a good rod/piston combo so I wouldn't really be worried about taxing the rods. But if you run that 14-16 psi range most of the time, I don't know if Id go through the effort to restall or changes converters. Just raise the shift points and leave it be unless you have a certain goal in mind that exceeds those limits.
You're using a good rod/piston combo so I wouldn't really be worried about taxing the rods. But if you run that 14-16 psi range most of the time, I don't know if Id go through the effort to restall or changes converters. Just raise the shift points and leave it be unless you have a certain goal in mind that exceeds those limits.
I was thinking with my EBC, setting it up so I can pour more boost on in high gear.
First gear won't handle 16 lbs, maybe 10lbs, second gear will be struggling at 16 lbs. as its already struggling for traction at 13lbs. and then roll out on 16-20+lbs. in third gear.
I'd probably have to have some kind of strategy like this anyways even at the track.
I’d leave it! Even if you turn it up and the drops only 400 rpms it’ll more than likely still be quicker. There’s a lot of fast stuff out there that sounds like a snow mobile goin down the track.
^Yeah and for drag race applications, most friends would rather have it drop 800-1000 on the shift vs 1500 and more.
I think I'd leave it alone.Out of curiousity, where does your combo make peak HP, what cam and what intake?
I think I'd leave it alone.Out of curiousity, where does your combo make peak HP, what cam and what intake?
No idea where I make peak HP, it's never been on a dyno, so I go by seat of the pants at the moment.
It pulls really hard to 7,000rpm and based on how fast it gets there I could probably go higher, just don't know if it's advisable.
The cam is a Brute Speed FI cam which Bob says peaks at 6,600rpm, intake is a Vic. Jr. w/ an Aaron's sheetmetal elbow and a Holley Dominator 105mm TB.
I'm thinking I'll leave it alone, keep turning it up and see where it leads.
I'm not hip to spending $1,500 on a converter if the return on performance isn't there.
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The more I think about it the more I think I want to leave it and just know that it will most likely be less efficient at higher boost levels that it won't see very often.
Now if I start mixing my own pump and meth that may change since meth is so cheap lol.
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Pro Torque came back to me recommending their U9 bolt together converter which starts at $1,900 with a spragless option.
Really didn't think my car was at that level but every now and then it's nice to be wrong lol.
Teching In
Joined: May 2013
Posts: 13
Likes: 0
I would't consider either one of those two options on a mostly street driven car, a mechanical diode is something that's going to need maintenance and a spragless converter creates more heat, depends how much ''street'' driving is done.
Circle D's option was a spragless unit as well, I don't know what spragless or mechanical diode refers too either.
My spragless PTC 9.5 doesn’t run hot either.
******- https://www.circledspecialties.com/b...nverter-sprags
plenty of info over on yellowbullet too.
******- https://www.circledspecialties.com/b...nverter-sprags
plenty of info over on yellowbullet too.
I wouldn't sweat the shift drop if you like how it drives and its 90% street.
Have you tried shifting it higher? You have good parts... it will couple harder at higher RPM. Maybe its a bit slushy because you are short shifting? Worth a try anyway.
What fluid are you running? Can run lower or higher viscosity trans fluid and it will also give you a few 100rpm in my experience.
Have you tried shifting it higher? You have good parts... it will couple harder at higher RPM. Maybe its a bit slushy because you are short shifting? Worth a try anyway.
What fluid are you running? Can run lower or higher viscosity trans fluid and it will also give you a few 100rpm in my experience.
I wouldn't sweat the shift drop if you like how it drives and its 90% street.
Have you tried shifting it higher? You have good parts... it will couple harder at higher RPM. Maybe its a bit slushy because you are short shifting? Worth a try anyway.
What fluid are you running? Can run lower or higher viscosity trans fluid and it will also give you a few 100rpm in my experience.
Have you tried shifting it higher? You have good parts... it will couple harder at higher RPM. Maybe its a bit slushy because you are short shifting? Worth a try anyway.
What fluid are you running? Can run lower or higher viscosity trans fluid and it will also give you a few 100rpm in my experience.
Fluid is John Deere Hy-Gard oil, I talked to a lot of guys using it who had good things to say and the price was right.
Hygard is great. If you aren't running the low viscosity version your are already tightening up the converter a tad with the standard viscosity Hygard. They make a low viscosity Hygard as well. I wouldn't be afraid of 7300 or so and turning up the boost on that combo. Give it a shot and see how it acts. I'm usually fighting too much drop on the shift...
Good luck!
Good luck!
Good morning gents,
Excited to share this update with everyone.
Went out and made a few hits last night, successfully moved my shifts into the 7,100-7,400 rpm range with boost topping out at 15.4 lbs.
I set the duty cycle up on a progressive ramp since I was fighting traction when too aggressive and with support from Chris at Sirhc Labs I now have a much steadier boost curve plus a 1 lb. boost drop between shifts instead of a 2 lb. spike which is great as I continue to lean harder on pump gas.
First Gear / 20% DC - 12 lbs.
Second Gear / 30% DC - 13.5 lbs.
Third Gear / 35% DC - 15.4 lbs.
Shift drop increased A LOT, it's now back up to where it was when I first started tuning the car which is just wild to me.
The 1-2 shift took place at 7,400 rpm as I was a little late and dropped 1,500 rpm down to 5,800 rpm, the 2-3 shift took place at 7,100 rpm and dropped 1,100 rpm down to 5,907 rpm.
With this I believe I'm now not falling back into the peak torque range so everything should be happier, the car sure seemed happier and man does it pull like a MF'er.
Any feedback is welcomed and thank you gents for you all your input, as always its much appreciated!
Happy to share any data anyone would like to see as well.
Excited to share this update with everyone.
Went out and made a few hits last night, successfully moved my shifts into the 7,100-7,400 rpm range with boost topping out at 15.4 lbs.
I set the duty cycle up on a progressive ramp since I was fighting traction when too aggressive and with support from Chris at Sirhc Labs I now have a much steadier boost curve plus a 1 lb. boost drop between shifts instead of a 2 lb. spike which is great as I continue to lean harder on pump gas.
First Gear / 20% DC - 12 lbs.
Second Gear / 30% DC - 13.5 lbs.
Third Gear / 35% DC - 15.4 lbs.
Shift drop increased A LOT, it's now back up to where it was when I first started tuning the car which is just wild to me.
The 1-2 shift took place at 7,400 rpm as I was a little late and dropped 1,500 rpm down to 5,800 rpm, the 2-3 shift took place at 7,100 rpm and dropped 1,100 rpm down to 5,907 rpm.
With this I believe I'm now not falling back into the peak torque range so everything should be happier, the car sure seemed happier and man does it pull like a MF'er.
Any feedback is welcomed and thank you gents for you all your input, as always its much appreciated!
Happy to share any data anyone would like to see as well.
Teching In
Joined: Dec 2022
Posts: 46
Likes: 9
From: SE Wisconsin
Good morning gents,
Excited to share this update with everyone.
Went out and made a few hits last night, successfully moved my shifts into the 7,100-7,400 rpm range with boost topping out at 15.4 lbs.
I set the duty cycle up on a progressive ramp since I was fighting traction when too aggressive and with support from Chris at Sirhc Labs I now have a much steadier boost curve plus a 1 lb. boost drop between shifts instead of a 2 lb. spike which is great as I continue to lean harder on pump gas.
First Gear / 20% DC - 12 lbs.
Second Gear / 30% DC - 13.5 lbs.
Third Gear / 35% DC - 15.4 lbs.
Shift drop increased A LOT, it's now back up to where it was when I first started tuning the car which is just wild to me.
The 1-2 shift took place at 7,400 rpm as I was a little late and dropped 1,500 rpm down to 5,800 rpm, the 2-3 shift took place at 7,100 rpm and dropped 1,100 rpm down to 5,907 rpm.
With this I believe I'm now not falling back into the peak torque range so everything should be happier, the car sure seemed happier and man does it pull like a MF'er.
Any feedback is welcomed and thank you gents for you all your input, as always its much appreciated!
Happy to share any data anyone would like to see as well.
Excited to share this update with everyone.
Went out and made a few hits last night, successfully moved my shifts into the 7,100-7,400 rpm range with boost topping out at 15.4 lbs.
I set the duty cycle up on a progressive ramp since I was fighting traction when too aggressive and with support from Chris at Sirhc Labs I now have a much steadier boost curve plus a 1 lb. boost drop between shifts instead of a 2 lb. spike which is great as I continue to lean harder on pump gas.
First Gear / 20% DC - 12 lbs.
Second Gear / 30% DC - 13.5 lbs.
Third Gear / 35% DC - 15.4 lbs.
Shift drop increased A LOT, it's now back up to where it was when I first started tuning the car which is just wild to me.
The 1-2 shift took place at 7,400 rpm as I was a little late and dropped 1,500 rpm down to 5,800 rpm, the 2-3 shift took place at 7,100 rpm and dropped 1,100 rpm down to 5,907 rpm.
With this I believe I'm now not falling back into the peak torque range so everything should be happier, the car sure seemed happier and man does it pull like a MF'er.
Any feedback is welcomed and thank you gents for you all your input, as always its much appreciated!
Happy to share any data anyone would like to see as well.
I'm gonna throw another 1-2 lbs. at it and if there's no knock and fuel is good I'll probably leave it for pump gas.
Timing was at 12 degrees in that area according to the data log.
Timing was at 12 degrees in that area according to the data log.