Need help with converter

-
Etor

Etor

Well-Known Member
Joined
May 7, 2017
Messages
67
Reaction score
27
Location
Europe
Hi, i want to change my converter as recommended in an other thread. I have a offer by PTC. PTC wrote me this: "We offer a 9.5" street strip converter for this combo. It will flash around 3000 to 3500 rpm's. It is a direct replacement converter. We run 7/16 x 20 holes in our billet front. You may have to drill flexplate holes."
Questions: What flexplate do i have now in my stock car (what holes?)? Is it a good idea to drill holes yourself? What flexplate could i use with the PTC converter without drilling holes?

Here my combo:
72 Dodge Demon, 3350 lbs, Stock 1972 LA 318, A904, Stock heads, Stock 2bbl intake with Carter BBD (i may change to Edelbrock Performer 2176 and Edelbrock 650 AVS), Stock cam, TTI headers to Dual exhaust 2.5“, 8.75 axle with suregrip 3.91 ratio.

I only drive on the streets, no track. With the stock converter i’m not happy. The car is a dog off the line. I want to have a quick acceleration in a optimal torque curve with the new converter.
Thanks, Etor
 
Last edited:
I'm not seeing a question here? Are you asking if this this is good convertor for your application the answers are maybe it will be optimal and yes, you will enjoy the car much more.

If they told you it would stall at 300-3500 behind your combo it's pretty obvious you didn't give them dyno specs. They can narrow it down almost exactly if you give them all of the info on the order form.

That being said a convertor should be sized to stall 500RPM over the engines peak torque RPM. This isn't always the optimal number for the street though. Other factors such as chassis etc also play a roll in convertor selection.

PTC is a great company and I've run their convertors with great success. You'll enjoy this new convertor greatly. Is it optimal to your combo, can't say.
 
Please read again. Questions (about flexplate) are in my first post, after the quote of the PTC answer.
 
2 barrel and headers on a stock cammed 318? You don't need that converter. Way overkill!
 
I have a 9.5 inch PTC converter. I had to buy new bolts and drill bigger holes in my flexplate. The stock bolts are so small in comparison. No issues so far and I don't expect any. This is my first "performance" converter but it's only a 2800 stall. I called PTC and told them what I have and they spec'd it out. It drives like stock on the street but it does take more RPM to power brake it. I'm happy.
20180220_210520.jpg
 
I gave them the same info about my combo like you see here. I dont have dyno test.someone knows about my flexplate?
 
1994redram said:
I had to buy new bolts and drill bigger holes in my flexplate. The stock bolts are so small in comparison. No issues so far and I don't expect any.
View attachment 1715156028
Click to expand...
Could you drill the old holes bigger (open up them)? Or did you have to drill complete new bigger holes? Is that not a matter of precision?
 
Etor said:
I dont understand converters. But PTC should understand their business, should n they?
Click to expand...
I think they just want to sell you something. Common sense tells me that converter is way overkill. Stock 318's don't produce much power after 3500 rpm.
 
I remember an el camino with a 3500 stall convertor. It was easier to push it into the shop than drive it. Not daily driver material thats for sure. Well at least not my cup of tea.
If i had a choice,2500 to 2800.
 
i'm with @toolmanmike . 3500 stall is WAY too much for a STOCK 318. TCI recommends a 1500-1700 RPM stall for that combo...with a max of 2400 stall
 
318's are pretty tough but with a 3500 stall and a 3:91 gear, a stock engine won't last the weekend.
 
Etor said:
Hi, i want to change my converter as recommended in an other thread. I have a offer by PTC. PTC wrote me this: "We offer a 9.5" street strip converter for this combo. It will flash around 3000 to 3500 rpm's. It is a direct replacement converter. We run 7/16 x 20 holes in our billet front. You may have to drill flexplate holes."
Questions: What flexplate do i have now in my stock car (what holes?)? Is it a good idea to drill holes yourself? What flexplate could i use with the PTC converter without drilling holes?

Here my combo:
72 Dodge Demon, 3350 lbs, Stock 1972 LA 318, A904, Stock heads, Stock 2bbl intake with Carter BBD (i may change to Edelbrock Performer 2176 and Edelbrock 650 AVS), Stock cam, TTI headers to Dual exhaust 2.5“, 8.75 axle with suregrip 3.91 ratio.

I only drive on the streets, no track. With the stock converter i’m not happy. The car is a dog off the line. I want to have a quick acceleration in a optimal torque curve with the new converter.
Thanks, Etor
Click to expand...
Like others have said, with what you've got for your engine setup, a converter over 2400 is too much for your engine. From the factory, there were two converters used with the 318/904 combination. Both would be what is called an 11" converter, and will have a 1" wide ring gear. There were two stall speeds, one around a maximum of 2000 the other around 2300. They way to tell the difference is the factory placed a decal on the converter body. One decal is tri-angular in shape and says "lo stall", the other is egg shaped and says "high stall". The addition of a manifold, carb, and exhaust system won't add enough horsepower or torque to justify anything much over 2400.
I don't understand why PTC would say you need a billet cover, 9.5" converter. The converter company I worked for prior to retirement might suggest one of their Pro Street converters with a stall of 2400-2500. The 7/16" mounting holes were only on race converters unless a customer requested them.
I hope this helps.
 
Tooljunkie said:
I remember an el camino with a 3500 stall convertor. It was easier to push it into the shop than drive it. Not daily driver material thats for sure. Well at least not my cup of tea.
If i had a choice,2500 to 2800.
Click to expand...

I run a 3500 convertor in my daily. Drives like normal. Even bumps when put into gear with an 800RPM idle. Sounds like that EL camino had a junk convertor or other issues.
 
roccodart440 said:
I run a 3500 convertor in my daily. Drives like normal. Even bumps when put into gear with an 800RPM idle. Sounds like that EL camino had a junk convertor or other issues.
Click to expand...


My PTC 2800 is the same. I have my idle set at 700 and it bumps when put in gear. It also moves at a pretty decent speed maybe 10 or so MPH in gear idling.

My neighbor has a ~475hp LS swapped C10 with a 3800 stall and it runs and drives like a normal vehicle.
 
FYI....
from jegs.com

1. How Do I choose the converter stall speed that is right for my application?
Answer:� Advertised stall speed will need to be at least 500 RPM higher than the beginning of the powerband of your camshaft. All aftermarket camshafts are supplied with a cam card that states RPM range.� If your camshaft states an RPM range of 1500-6500, for example, you would want to select a torque with a minimum of 2,000 RPM stall� For a street car it is wise to also select a torque converter stall speed that is below the engine RPM at 65 MPH to prevent excessive heat build up.

roccodart440 said:
with a tallish tire it would turn 2600@58mph. That doesn't sound too crazy.
Click to expand...

Which means he needs a converter with a 2100 or less stall.... see above

With his 3.91, assuming a 28 in tall tire, puts his RPMs at 2491~ @ 65 mph... so again, less than that for stall RPM...

A billet converter with that speed is meant for drag racing. Period.
 
A few things to keep in mind.
Flash stall and brake stall rpms will vary with the engine's torque. Just because PTC calls it a 3500 rpm converter, may or may not mean that's what it will actually flash to behind this engine. If its what they call this particular converter, then it won't. It takes a certain amount of torque to attain a given stall number.

Drilling flexplates. Me - I wouldn't do it. I've broken too many flexplates. If you have a self centering bit, feed it so the heat buildup is minimum and its probably OK.

I'd take a look at the Mopar Performance Chassis Book to see what guidance they may provide. Also see what info you can get from Turbo-Action and maybe a third manufacturer as well.
 
Cam card rpm ranges are total BS. If you believe what they say i'll sell you a pet unicorn for a fair price. Even the MPP cams aren't accurate.

Stall speed varies by combo. In other words, many factors figure into where a convertor stalls. Torque being one of them. Ever wonder how guys with OD transmissions run higher stall convertors without issue? I mean jeez driving down the road at rpms 1,000+ rpm less than stall speed. It must be slipping bad, right? No, the engine isn't making as much torque there so the stall speed is lower.

If you are ordering a convertor from a reputable company you should have a dyno sheet and all of the combo information. If you don't there IS some guesswork involved. If you think a 3500+ convertor can't be reliably run on the street (not debating if it is right for his car, which it most likely isn't) I feel sorry for you. Convertor manufacturer companies disagree with you. They can be used.

His combo likely could live with less stall, sure. Would this one wake it up? Yeah, I'm sure of it. Is there a more ideal choice, yup, most likely. Does it leave him room to grow? Yes indeed.

If the stock stall was 2,000-2,300. I wouldn't think 500 over would be out of the question. So 2,500 - 3,1,000.

I'd like to know what the OP engine makes on a dyno and I'd like to know if he plans on upgrading to more HP.
 
Just by installing an X pipe on my 408, it changed the stall. I agree with a cam card stall being BS. Lots of variables. ^^^^ :thumbsup:
 
roccodart440 said:
Cam card rpm ranges are total BS. If you believe what they say i'll sell you a pet unicorn for a fair price. Even the MPP cams aren't accurate.

Stall speed varies by combo. In other words, many factors figure into where a convertor stalls. Torque being one of them. Ever wonder how guys with OD transmissions run higher stall convertors without issue? I mean jeez driving down the road at rpms 1,000+ rpm less than stall speed. It must be slipping bad, right? No, the engine isn't making as much torque there so the stall speed is lower.

If you are ordering a convertor from a reputable company you should have a dyno sheet and all of the combo information. If you don't there IS some guesswork involved. If you think a 3500+ convertor can't be reliably run on the street (not debating if it is right for his car, which it most likely isn't) I feel sorry for you. Convertor manufacturer companies disagree with you. They can be used.

His combo likely could live with less stall, sure. Would this one wake it up? Yeah, I'm sure of it. Is there a more ideal choice, yup, most likely. Does it leave him room to grow? Yes indeed.

If the stock stall was 2,000-2,300. I wouldn't think 500 over would be out of the question. So 2,500 - 3,1,000.

I'd like to know what the OP engine makes on a dyno and I'd like to know if he plans on upgrading to more HP.
Click to expand...
im not talking in general... I'm talking about HIS combo in HIS car. a STOCK 318... that has the stock 2 barrel intake, the stock heads, the stock carb, the stock cam.
 
You must log in or register to reply here.
-

Back
Top