Ls2 408 stroker
06-05-2019, 01:06 AM
#61
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Larger motors are going to generate a surplus of low and mid range torque/power compared to smaller motors. If you are going big, it is best to focus big. Otherwise, max out something smaller and more sensible.
The formula for strokers that seems to work best is to aim for the f!ck!ng stars! You end up with beautiful 700hp 400ci engines on off the shelf heads, just have to follow the right recipe for success.
The formula for strokers that seems to work best is to aim for the f!ck!ng stars! You end up with beautiful 700hp 400ci engines on off the shelf heads, just have to follow the right recipe for success.
At least I am now
06-05-2019, 01:11 AM
#62
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For the street with an auto** I agree about runner length I suppose, but then I wouldn't let yourself be disappointed by the peak numbers. I have a 402 in my rx7 that everyone critiques when I post a dyno sheet, but I've been 130 in the quarter with it which I'm quite happy with. You should never really be doing a pull at 3000 rpm, but with a stalled auto that flashes to ~3200 rpm it'll happen pretty often. You're building to your application instead of trying to hit a dyno number which is the right way to go. With a manual you can change how you drive to utilize the higher rpm powerband. With an auto you're kinda stuck with the long ratios.
Your engine is going to be a beast regardless of what the peak numbers on the dyno say. Your butt dyno should be very happy. The 415 we built feels like an animal compared to the stock bottom end ls3. We were able to tighten the converter which improved efficiency on the finish line and increased mph without having to take rear gear ratio out of it.
Without a 6000 stall converter I wouldn't put the short runners in it. Torque the thing down the road. Ideally you want the stall speed of the converter to be high enough for the RPM to fall into the converter when you shift. You can get torque multiplication benefit off the shift that can be stronger than the gear ratio benefits that Darth mentioned above. I'd consider in the future maybe creeping up on stall speed to ~4500 rpm which shouldn't be too far off your torque peak. I've driven cars that are faster down the dragstrip actually shifting BEFORE peak power to utilize the converter on the gear recovery.
Your engine is going to be a beast regardless of what the peak numbers on the dyno say. Your butt dyno should be very happy. The 415 we built feels like an animal compared to the stock bottom end ls3. We were able to tighten the converter which improved efficiency on the finish line and increased mph without having to take rear gear ratio out of it.
Without a 6000 stall converter I wouldn't put the short runners in it. Torque the thing down the road. Ideally you want the stall speed of the converter to be high enough for the RPM to fall into the converter when you shift. You can get torque multiplication benefit off the shift that can be stronger than the gear ratio benefits that Darth mentioned above. I'd consider in the future maybe creeping up on stall speed to ~4500 rpm which shouldn't be too far off your torque peak. I've driven cars that are faster down the dragstrip actually shifting BEFORE peak power to utilize the converter on the gear recovery.
My stall speed will need to be higher or else my car will be a turd off the line.
For a street car it's not worth it and losing a lot of torque off idle to 6000rpm.
Won't be good to drive. You will need to really rev the car to get it moving.
I want an effortless drive.
06-05-2019, 01:12 AM
#63
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06-05-2019, 07:49 AM
#64
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I thought to give you all another update on my build.
I received a phone call from my engine builder today in regards to the stall.
He spoke to TCE converters about my vehicle and what camshaft was in it etc.
They said to him that there is a very high chance that the converter will need to be modified as it will most certainly be flashing at a higher rpm with such a cam specification and with double the overlap
So to save time and labour while the engine is out of the vehicle, its best to take it out and send the current converter so it can be modified.
It will most likely end up being a 3600rpm stall at a guess by my tuner and I but I was very specific in wanting it to drive really good on the street like it does now especially in the low end.
It is a lock up converter too.
I can recall one time when I had a 223/231 111LSA camshaft in my stroker engine (yes I know this camshaft was not suitable but didn't have much choice till i could get another one)
I had a 2200rpm stall. This worked fine. Cam had 5 degrees of overlap. When i fitted the 236/244 114 LSA camshaft a few weeks later this stall ended up turning into a 4600rpm stall and it was pushing like crazy on the brakes at 850rpm idle.
And that was with double the overlap of the 223/231 cam
I have a feeling the same thing would happen with the current converter although it may be less dramatic.
Who knows.
I received a phone call from my engine builder today in regards to the stall.
He spoke to TCE converters about my vehicle and what camshaft was in it etc.
They said to him that there is a very high chance that the converter will need to be modified as it will most certainly be flashing at a higher rpm with such a cam specification and with double the overlap
So to save time and labour while the engine is out of the vehicle, its best to take it out and send the current converter so it can be modified.
It will most likely end up being a 3600rpm stall at a guess by my tuner and I but I was very specific in wanting it to drive really good on the street like it does now especially in the low end.
It is a lock up converter too.
I can recall one time when I had a 223/231 111LSA camshaft in my stroker engine (yes I know this camshaft was not suitable but didn't have much choice till i could get another one)
I had a 2200rpm stall. This worked fine. Cam had 5 degrees of overlap. When i fitted the 236/244 114 LSA camshaft a few weeks later this stall ended up turning into a 4600rpm stall and it was pushing like crazy on the brakes at 850rpm idle.
And that was with double the overlap of the 223/231 cam
I have a feeling the same thing would happen with the current converter although it may be less dramatic.
Who knows.
06-05-2019, 11:03 AM
#66
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I don't the lock up makes any difference to stall speed.
I don't want it to stall too high because it changes the driving manners of the vehicle.
I remember when I put in the 236/244 cam with that stall, I lost torque down low and the car wanted to rev more plus I had pushing on the brakes as mentioned earlier.
When I fitted the 3200rpm stall to the camshaft, voila! Problem fixed and I got my low end manners back along with more torque and it just drove better. And no pushing on the brakes.
It just shoots up to the rpm its meant to smoothly and decisively, unlike the 2200rpm that didn't.
06-05-2019, 12:00 PM
#67
That's a strange experience you had with needing to push the brakes harder on the other engine package. A looser converter is a requirement when you go to a larger cam both to match the powerband, but also to prevent pushing through the brakes. A tighter converter is what is going to try to pull the car during idle, and a larger cam also produces less brake assist at idle.
The lock-up does not impact stall speed - but it is basically your get out of jail free card...you can leave it loose and let the engine flash for better performance, but when you're cruising you simply let it lock up and now you're 1:1. You can also lock it going down track if the clutches are strong enough internally.
A looser converter will also smooth out bucking or surging from a large cam.
I suspect what happened with the other converter is you actually over powered it. You should not have jumped from 2200 rpm to 4600 rpm from a simple cam change. That should take hundreds of ft lbs. There was something physically wrong internally, or you were blowing through it. Same as a clutch...you can go past the efficiency curve of the components in the converter and you basically do nothing but "slip".
Flashing high and multiplying torque is what you want. It is a great idea to have the converter cut open to inspect it, and also dial it in for the new performance of the engine. You can probably expect ~575 ft lb at the flywheel, and a stall speed of 4500 rpm would be a huge performance gain, and anything over 35mph you can probably leave the converter locked up.
The lock-up does not impact stall speed - but it is basically your get out of jail free card...you can leave it loose and let the engine flash for better performance, but when you're cruising you simply let it lock up and now you're 1:1. You can also lock it going down track if the clutches are strong enough internally.
A looser converter will also smooth out bucking or surging from a large cam.
I suspect what happened with the other converter is you actually over powered it. You should not have jumped from 2200 rpm to 4600 rpm from a simple cam change. That should take hundreds of ft lbs. There was something physically wrong internally, or you were blowing through it. Same as a clutch...you can go past the efficiency curve of the components in the converter and you basically do nothing but "slip".
Flashing high and multiplying torque is what you want. It is a great idea to have the converter cut open to inspect it, and also dial it in for the new performance of the engine. You can probably expect ~575 ft lb at the flywheel, and a stall speed of 4500 rpm would be a huge performance gain, and anything over 35mph you can probably leave the converter locked up.
06-05-2019, 12:12 PM
#68
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Thread Starter
That's a strange experience you had with needing to push the brakes harder on the other engine package. A looser converter is a requirement when you go to a larger cam both to match the powerband, but also to prevent pushing through the brakes. A tighter converter is what is going to try to pull the car during idle, and a larger cam also produces less brake assist at idle.
The lock-up does not impact stall speed - but it is basically your get out of jail free card...you can leave it loose and let the engine flash for better performance, but when you're cruising you simply let it lock up and now you're 1:1. You can also lock it going down track if the clutches are strong enough internally.
A looser converter will also smooth out bucking or surging from a large cam.
I suspect what happened with the other converter is you actually over powered it. You should not have jumped from 2200 rpm to 4600 rpm from a simple cam change. That should take hundreds of ft lbs. There was something physically wrong internally, or you were blowing through it. Same as a clutch...you can go past the efficiency curve of the components in the converter and you basically do nothing but "slip".
Flashing high and multiplying torque is what you want. It is a great idea to have the converter cut open to inspect it, and also dial it in for the new performance of the engine. You can probably expect ~575 ft lb at the flywheel, and a stall speed of 4500 rpm would be a huge performance gain, and anything over 35mph you can probably leave the converter locked up.
The lock-up does not impact stall speed - but it is basically your get out of jail free card...you can leave it loose and let the engine flash for better performance, but when you're cruising you simply let it lock up and now you're 1:1. You can also lock it going down track if the clutches are strong enough internally.
A looser converter will also smooth out bucking or surging from a large cam.
I suspect what happened with the other converter is you actually over powered it. You should not have jumped from 2200 rpm to 4600 rpm from a simple cam change. That should take hundreds of ft lbs. There was something physically wrong internally, or you were blowing through it. Same as a clutch...you can go past the efficiency curve of the components in the converter and you basically do nothing but "slip".
Flashing high and multiplying torque is what you want. It is a great idea to have the converter cut open to inspect it, and also dial it in for the new performance of the engine. You can probably expect ~575 ft lb at the flywheel, and a stall speed of 4500 rpm would be a huge performance gain, and anything over 35mph you can probably leave the converter locked up.
That 2200rpm converter was made by another company.
It was originally a 3200rpm which drove absolutely terrible because it was way too tight. The vehicle would not move till the revs hit 2600rpm.
I had to get TCE to modify it back down to a 2500rpm when I changed camshaft and that same stall was modified again to a 2200rpm when I changed camshaft again so it's been through quite a bit,
The 3200rpm unit I have now was a completely new unit from TCE so it's all good.
I would assume the adjustment with this converter with my new cam will be made a little looser.
06-05-2019, 12:37 PM
#70
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06-05-2019, 02:01 PM
#71
Our way of describing how the converter works is a little different.
tight = lower stall
loose = higher stall
Stall torque ratio is independent of how loose or tight the converter is. Stall torque ratio determines the maximum torque multiplication at stall speed.
You generally want to match your stall speed to around torque peak. I think your peak torque is going to be a table top from ~4500 rpm to 5200 rpm.
tight = lower stall
loose = higher stall
Stall torque ratio is independent of how loose or tight the converter is. Stall torque ratio determines the maximum torque multiplication at stall speed.
You generally want to match your stall speed to around torque peak. I think your peak torque is going to be a table top from ~4500 rpm to 5200 rpm.
06-05-2019, 02:05 PM
#72
A tighter stall is just that... it is tighter under part throttle keeping the RPMs lower. This really only matters if you have a wake the dead loud exhaust. Nobody wants to be at 3000 RPM barely moving with 120db exhaust blaring. A looser stall drives worse and needs more RPM to move with part throttle. So it makes the car feel more lethargic with part throttle. But once it flashes... it's much better than a tighter stall. And it provides more shift extension and better coupling at higher RPM. For most LS cars... a 4000-4400 stall is a good match for the engine torque while maintaining streetability.
06-05-2019, 02:25 PM
#73
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Thread Starter
A tighter stall is just that... it is tighter under part throttle keeping the RPMs lower. This really only matters if you have a wake the dead loud exhaust. Nobody wants to be at 3000 RPM barely moving with 120db exhaust blaring. A looser stall drives worse and needs more RPM to move with part throttle. So it makes the car feel more lethargic with part throttle. But once it flashes... it's much better than a tighter stall. And it provides more shift extension and better coupling at higher RPM. For most LS cars... a 4000-4400 stall is a good match for the engine torque while maintaining streetability.
I hated the way the loose stall drove. The car literally would not move till you hit 2600rpm.
It lasted about 2 weeks and I had to get it modified. I remember how pissed off I was.
The guy I was dealing with back then who organised it was a moron.
It was set up incorrectly.
My goal with a stall is to have great driveability.
06-05-2019, 05:29 PM
#76
4l80 with lock up in 4th. Drives very tight as is and still have lock up in 4th so I'll good with looser
06-05-2019, 05:52 PM
#77
4L80 is a different beast... I'm assuming you're getting a 5000 stall out of a 10.5" converter?
Move to a 9.5" or smaller with the 4L60 and it's very easy to push to 5000+ stalls... but they are super loose.
And lockup isn't what the issue is. I don't even care about that... I drive at 2800RPM at 70 now with lockup and overdrive due to gearing. But, what I care about goosing the throttle slightly and nothing happening.
Move to a 9.5" or smaller with the 4L60 and it's very easy to push to 5000+ stalls... but they are super loose.
And lockup isn't what the issue is. I don't even care about that... I drive at 2800RPM at 70 now with lockup and overdrive due to gearing. But, what I care about goosing the throttle slightly and nothing happening.
06-05-2019, 06:49 PM
#79
4L80 is a different beast... I'm assuming you're getting a 5000 stall out of a 10.5" converter?
Move to a 9.5" or smaller with the 4L60 and it's very easy to push to 5000+ stalls... but they are super loose.
And lockup isn't what the issue is. I don't even care about that... I drive at 2800RPM at 70 now with lockup and overdrive due to gearing. But, what I care about goosing the throttle slightly and nothing happening.
Move to a 9.5" or smaller with the 4L60 and it's very easy to push to 5000+ stalls... but they are super loose.
And lockup isn't what the issue is. I don't even care about that... I drive at 2800RPM at 70 now with lockup and overdrive due to gearing. But, what I care about goosing the throttle slightly and nothing happening.
06-06-2019, 01:46 AM
#80
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They will not make much more power after 5500rpm and they do not flow as well at higher lifts like the square ports.
The square ports make more than enough torque in the low and mid range anyway.