Death wish? 4.8 turbo build
06-02-2017, 07:42 AM
#42
Issue is you are running a 4.8. They need to be in a higher RPM range to work well and not hurt parts. At your weight with 800hp you should be around 117-120mph in the 1/8th. a 3.70 and 28” tire you’ll be at 5300-5400ish RPM. Which is not where the 4.8 is happy. Even with a 4.60 gear you’ll be at 120-125 depending on slip @ 7k.
06-03-2017, 04:30 AM
#43
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Issue is you are running a 4.8. They need to be in a higher RPM range to work well and not hurt parts. At your weight with 800hp you should be around 117-120mph in the 1/8th. a 3.70 and 28” tire you’ll be at 5300-5400ish RPM. Which is not where the 4.8 is happy. Even with a 4.60 gear you’ll be at 120-125 depending on slip @ 7k.
I apologize now if it seems like im going in circles, work has been wild crazy and dealing with the humidity all week drains my brain capacity. Wish these airplanes would stop breaking LOL
06-03-2017, 11:00 AM
#44
Add 10% to rpm
06-03-2017, 05:53 PM
#45
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06-03-2017, 08:50 PM
#46
shouldnt i add a 10 mph to desired trap speed to account for slip? that would put me at a 4.30 gear?
I apologize now if it seems like im going in circles, work has been wild crazy and dealing with the humidity all week drains my brain capacity. Wish these airplanes would stop breaking LOL
I apologize now if it seems like im going in circles, work has been wild crazy and dealing with the humidity all week drains my brain capacity. Wish these airplanes would stop breaking LOL
06-03-2017, 10:38 PM
#47
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If the cars only gonna trap 117-120 ish a 4.30 would do 136 @ 7k plus the slip. If the converters spec'd right you shouldn't slip more than 5-8% Even 10% would put you at 123ish. Turbos do like load to an extent, but the converter will couple better at higher RPM as well. I'd want alot of gear in an 1/8th mile car if I wanted to be competitive with a 4.8. 7k is also nowhere near the redline capability of a 4.8 depending on your parts combo. But you will need decent suspension to hook it. Could run a really loose converter and taller gear, some guys make that work as well.
06-04-2017, 10:21 PM
#48
The intake and valve train mainly. Which truck intake do you have? You can buzz the factory intakes to 7200, but none of them are happy there. Might be worth it for the low and mid range if you have the TBSS style truck intake. Just need to decide where you are going to rev it and try to match the parts to the RPM range as closely as you can.
I'd gear it to make use of that 7200 RPM with an aftermarket intake if the budget allows for it. You can always dumb the power way down on the launch and ramp it back in. With the right converter, a 4.30 would be fine IMO. Esp if you can rev it out to 7200ish. But you need to know how much the converter will slip. I'd call PTC and ask what they would suggest with your part combo in an 1/8th mile car.
I'd gear it to make use of that 7200 RPM with an aftermarket intake if the budget allows for it. You can always dumb the power way down on the launch and ramp it back in. With the right converter, a 4.30 would be fine IMO. Esp if you can rev it out to 7200ish. But you need to know how much the converter will slip. I'd call PTC and ask what they would suggest with your part combo in an 1/8th mile car.
06-05-2017, 09:20 AM
#49
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The intake and valve train mainly. Which truck intake do you have? You can buzz the factory intakes to 7200, but none of them are happy there. Might be worth it for the low and mid range if you have the TBSS style truck intake. Just need to decide where you are going to rev it and try to match the parts to the RPM range as closely as you can.
I'd gear it to make use of that 7200 RPM with an aftermarket intake if the budget allows for it. You can always dumb the power way down on the launch and ramp it back in. With the right converter, a 4.30 would be fine IMO. Esp if you can rev it out to 7200ish. But you need to know how much the converter will slip. I'd call PTC and ask what they would suggest with your part combo in an 1/8th mile car.
I'd gear it to make use of that 7200 RPM with an aftermarket intake if the budget allows for it. You can always dumb the power way down on the launch and ramp it back in. With the right converter, a 4.30 would be fine IMO. Esp if you can rev it out to 7200ish. But you need to know how much the converter will slip. I'd call PTC and ask what they would suggest with your part combo in an 1/8th mile car.
As soon as a gear is selected (which 4.30 seems like it) ill be getting in contact with ptc for converter.
From the reseach ive been doing, i see that launching the 4.8 at low boost works best and ramping up to full boost over a sec or so. Im assuming that all somes down to tuning. Or do i need one of those fancy co2 controllers?
06-05-2017, 09:41 AM
#50
I'd ask PTC what gear they would suggest with your RPM range first. They would know better than I would.
Look here for a max effort 4.8 setup. Holley or similar intakes for power over 6k seems like a common choice. Even the cheezy china intakes with the short runners seem to perform well from 6k and up...
https://ls1tech.com/forums/forced-in...6mm-notch.html
Look here to get a good idea of where each of the intake makes power.
http://www.hotrod.com/articles/20-ls...ifolds-tested/
Don't need C02 boost control with a decent aftermarket ECU like the MS3. But it can implement it if you want it as well. No need for aftermarket controllers. Retarding timing based off time from the trans brake release is the easiest, fastest method IMO. If you need to pull more you can do the same with boost.
Look here for a max effort 4.8 setup. Holley or similar intakes for power over 6k seems like a common choice. Even the cheezy china intakes with the short runners seem to perform well from 6k and up...
https://ls1tech.com/forums/forced-in...6mm-notch.html
Look here to get a good idea of where each of the intake makes power.
http://www.hotrod.com/articles/20-ls...ifolds-tested/
Don't need C02 boost control with a decent aftermarket ECU like the MS3. But it can implement it if you want it as well. No need for aftermarket controllers. Retarding timing based off time from the trans brake release is the easiest, fastest method IMO. If you need to pull more you can do the same with boost.
06-05-2017, 12:04 PM
#51
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well i always wanted a Hi Ram and people keep giving me reasons to get one. looks like it will be added to the build list.
Talked to PTC this morning and threw yet another wrench in my thought process. He couldnt point me in the right direction since to his knowledge of turbo cars hes worked with were running 3.08-3.25 gears for 1/4 mile. Honestly i didnt see that coming
ill be running a Mircosquirt which is basically a MS2. When it comes time to tune this monster, i may trailer it up to KS and have Forcefed86 learn me some tuning
Talked to PTC this morning and threw yet another wrench in my thought process. He couldnt point me in the right direction since to his knowledge of turbo cars hes worked with were running 3.08-3.25 gears for 1/4 mile. Honestly i didnt see that coming
ill be running a Mircosquirt which is basically a MS2. When it comes time to tune this monster, i may trailer it up to KS and have Forcefed86 learn me some tuning
06-05-2017, 04:18 PM
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Called Dusty, waiting for a return call. Thinking maybe i just gear it for 1/4 mile. Its raining and im awaiting parts so ive been trying to read up on combos all day. That 8.29 notch back was runnings 3.55, other turbo 4.8/5.3 reving to 7000+ are all 3.08-3.70... some run 1/8, some run 1/4. Chances are after a few more beers ill get pissed and create another thread asking turbo gearing
06-05-2017, 05:14 PM
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06-05-2017, 06:50 PM
#58
06-06-2017, 07:36 AM
#60
I am planning on running 4.56s and a 29.5" tire (M&H 390s) with my build.
You typically run low-3 series gears with shorter tires and lower revving engines - like a Buick V6 that wheezes out at 5500rpm. Not these 4.8s that are very leggy.
On the converter side you will probably be in the 3800-4400 range depending upon how much boost you can launch with (whether it is programmable or mechanically limited). Nobody likes blowing through the converter on the brake or up the track, same goes for blowing the tires off on the launch.
You typically run low-3 series gears with shorter tires and lower revving engines - like a Buick V6 that wheezes out at 5500rpm. Not these 4.8s that are very leggy.
On the converter side you will probably be in the 3800-4400 range depending upon how much boost you can launch with (whether it is programmable or mechanically limited). Nobody likes blowing through the converter on the brake or up the track, same goes for blowing the tires off on the launch.