uk-maxie
Well-Known Member
Hi all, looking for a bit of help to understand what stall speed we need for our application.
I've read thru many threads on here which have given conflicting info, so still none the wiser to be honest!
It's a 69 Sport Satellite that we recently fitted a 493 stroker from a well known and well-regarded (as far as i know) engine builder. We asked them to source a compatible converter and ship it over to us in the UK with the engine, which they did.
Once the engine was built and dyno'd they gave TCI the info and shipped the lot as arranged.
As soon as we had it all up and running we noticed a big difference in how the trans worked compared to how our old set up was, which we knew was never quite right. What we used to find was that the engine revs would drop a few hundred when going from neutral to drive, so consequently we had to have the idle speed set quite high in neutral so it didnt drop too low when put in gear. It seemed a bit more sluggish than it should have too. So from what I understand now i guess we had a converter with too low a stall speed.
With the new combo we noticed that we didnt have this problem and that the engine revved freely and felt really lively. So all seemed fine and dandy!
But we soon realised that the firmness of the shifts had all but disappeared (the shift kit in the trans used to give firm shifts) and it felt like it was always slipping when driving at slower speeds. So we started to look into what converter had been supplied.
We found that it's a Super Streetfighter which i've just been told by TCI after emailing them has a stall speed of 3500.We were thinking it was around 3000 so it's even worse than we thought!
This maybe fine for a car that spends most of its time on the 1/4 mile but 95% time we'll be using the car for driving to events with the occasional bit of racing. So most of the time we'll be at 50-70 mph, ie 2000-3000 rpm.
The engine spec was always intended to be streetable and be able to cope with traffic and work with power brakes, so it has a 484 purple shaft with 114 lsa and 241 deg duration at 0.050. Rear gears are 3.55 and rear tires are 28" tall.
When I asked the engine builder why we'd been charged over $900 for the converter, they said TCI were worried that 'we would have an issue due to the torque we are making'. The dyno sheet shows 687 lbft @ 4200!
In the next couple of weeks we are hoping to have the car put on a rolling road so we'll see how realistic this number really is (allowing for losses etc) but at it stands, it looks to me that if TCI's sole criteria for selecting a converter for our application, given all the above info, was just the torque it's making, we've paid way more than necessary as it's most likely - according to everyone i've spoken to - that figure is optimistic to say the least! And from a seat-of-the-pants point of view, that stall is way too high also.
The guy at TCI who confirmed the stall is 3500 is convinced it's the right converter for the job.
So, I was hoping to get some second opinions, especially if anyone else here has a 440 with a fairly mild cam. This cam has a range of 2200-6000, so going by a theory I got from a Summit video on Youtube, we need a stall speed 500 rpm greater than the starting range of the cam. Which puts us at 2700.
Any thought, anyone? Thanks in advance
I've read thru many threads on here which have given conflicting info, so still none the wiser to be honest!
It's a 69 Sport Satellite that we recently fitted a 493 stroker from a well known and well-regarded (as far as i know) engine builder. We asked them to source a compatible converter and ship it over to us in the UK with the engine, which they did.
Once the engine was built and dyno'd they gave TCI the info and shipped the lot as arranged.
As soon as we had it all up and running we noticed a big difference in how the trans worked compared to how our old set up was, which we knew was never quite right. What we used to find was that the engine revs would drop a few hundred when going from neutral to drive, so consequently we had to have the idle speed set quite high in neutral so it didnt drop too low when put in gear. It seemed a bit more sluggish than it should have too. So from what I understand now i guess we had a converter with too low a stall speed.
With the new combo we noticed that we didnt have this problem and that the engine revved freely and felt really lively. So all seemed fine and dandy!
But we soon realised that the firmness of the shifts had all but disappeared (the shift kit in the trans used to give firm shifts) and it felt like it was always slipping when driving at slower speeds. So we started to look into what converter had been supplied.
We found that it's a Super Streetfighter which i've just been told by TCI after emailing them has a stall speed of 3500.We were thinking it was around 3000 so it's even worse than we thought!
This maybe fine for a car that spends most of its time on the 1/4 mile but 95% time we'll be using the car for driving to events with the occasional bit of racing. So most of the time we'll be at 50-70 mph, ie 2000-3000 rpm.
The engine spec was always intended to be streetable and be able to cope with traffic and work with power brakes, so it has a 484 purple shaft with 114 lsa and 241 deg duration at 0.050. Rear gears are 3.55 and rear tires are 28" tall.
When I asked the engine builder why we'd been charged over $900 for the converter, they said TCI were worried that 'we would have an issue due to the torque we are making'. The dyno sheet shows 687 lbft @ 4200!
In the next couple of weeks we are hoping to have the car put on a rolling road so we'll see how realistic this number really is (allowing for losses etc) but at it stands, it looks to me that if TCI's sole criteria for selecting a converter for our application, given all the above info, was just the torque it's making, we've paid way more than necessary as it's most likely - according to everyone i've spoken to - that figure is optimistic to say the least! And from a seat-of-the-pants point of view, that stall is way too high also.
The guy at TCI who confirmed the stall is 3500 is convinced it's the right converter for the job.
So, I was hoping to get some second opinions, especially if anyone else here has a 440 with a fairly mild cam. This cam has a range of 2200-6000, so going by a theory I got from a Summit video on Youtube, we need a stall speed 500 rpm greater than the starting range of the cam. Which puts us at 2700.
Any thought, anyone? Thanks in advance
