Death wish? 4.8 turbo build
06-06-2017, 08:01 AM
#61
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So then what Forcefed86 and I were saying about 4.30 gears for my 28 inch tires and crossing at 7200 +/- is actually on track? just gonna need A LOT of trial and error, tuning and right converter
06-06-2017, 08:48 AM
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06-06-2017, 09:03 AM
#63
I am just building mine for the sensation of going fast and making lots of cool noises.
I dug up an old thread from the early-2000s where the Turbo Buick guys got pissy when I put 3.08s in my car (claiming it would slow me down, it didn't). Those engines need lots of load at the low end of the rev range and can make huge torque off the line which tapers off quickly due to a short power window. You are going to see something really different here with an engine that makes power for days toward the much more elevated redline.
I'd be curious to know what the recommended RPM drop on your 1-2 shift is going to be (assuming you stick with the PG).
06-06-2017, 09:47 AM
#64
The main issue I see is 1/8th VS 1/4. Need pick one. If you want to do both you need to set it up for the ¼.
Tell Dusty your weight, WHP, and rev limit. Then ask him what gearing he would suggest for a max effort 4.8 in the 1/8th or ¼ with your specs. The gearing and converter will be setup differently for each.
1/8th mile is all about traction. With a glide you don’t have the short 1st gear like the th400’s, so you can get away with a shorter final gear. But If you aren’t confident you can plant the tire and keep it planted well, don’t put a 4.30 in it.
Tell Dusty your weight, WHP, and rev limit. Then ask him what gearing he would suggest for a max effort 4.8 in the 1/8th or ¼ with your specs. The gearing and converter will be setup differently for each.
1/8th mile is all about traction. With a glide you don’t have the short 1st gear like the th400’s, so you can get away with a shorter final gear. But If you aren’t confident you can plant the tire and keep it planted well, don’t put a 4.30 in it.
Last edited by Forcefed86; 06-06-2017 at 10:10 AM.
06-07-2017, 07:16 PM
#67
Got my setup dynoed today.... While I see this as disappointment, some might see it differently. I made 620 on 15# then I started to lean out. So I just gave the car to my tuner and told him to upgrade my entire fuel system so I can try for 1k the next go around.
06-07-2017, 07:23 PM
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but im loving the update. Let me know what happens. what cam specs are you running? pm me details, not to air out build secrets lol
06-07-2017, 07:31 PM
#69
Yea definetly the pump. The single 450 I have wasn't enough. My tuner said that was the only problem... I needed more pump. The injectors were fine and weren't at its limit yet. I'm running a Btr stage 2 turbo cam. He also aid the cam is pretty big for a 4.8 and that the motor wanted to spin all the way to like 7k but that's not ideal for a gen 3 motor and rods.
06-08-2017, 04:57 PM
#71
Your attempting 1K WHP with Gen 3 rods?
06-08-2017, 06:44 PM
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06-08-2017, 09:52 PM
#76
Select gear based on tire height and rpm minus 8 to 10% for slip. Confirm slip with PTC. With 28" tire and 900whp, 4.8x gear puts you at 7300 before slip rpm added. Push the SBE gen 3 towards your goal. Keep adding boost and optimize the tune to see where the mechanical limits are. Maybe 900whp on gen3 rods is it.
Side note - gearing for 1/4 is night and day difference to 1/8. At your
weight, 900whp and target rpm, 1/4 gear 3.80ish.
06-09-2017, 12:06 AM
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Ox, if this is a dedicated 1/8 mile E85 car and looking for best results. Setup the motor to run 8000-8200rpm. Static 9.5CR not ideal for E85. With cam to run >8000, dynamic CR is going to be lower than optimum for E85. I'd target 10.5 to 11 - 1 for E85. Truck intake should be ok (guys running 6.0 with truck intake to 6400, math says 4.8 to 8000). Gonna need 900ish whp for 5.3 in 1/8 at around 125mph.
Select gear based on tire height and rpm minus 8 to 10% for slip. Confirm slip with PTC. With 28" tire and 900whp, 4.8x gear puts you at 7300 before slip rpm added. Push the SBE gen 3 towards your goal. Keep adding boost and optimize the tune to see where the mechanical limits are. Maybe 900whp on gen3 rods is it.
Side note - gearing for 1/4 is night and day difference to 1/8. At your
weight, 900whp and target rpm, 1/4 gear 3.80ish.
Select gear based on tire height and rpm minus 8 to 10% for slip. Confirm slip with PTC. With 28" tire and 900whp, 4.8x gear puts you at 7300 before slip rpm added. Push the SBE gen 3 towards your goal. Keep adding boost and optimize the tune to see where the mechanical limits are. Maybe 900whp on gen3 rods is it.
Side note - gearing for 1/4 is night and day difference to 1/8. At your
weight, 900whp and target rpm, 1/4 gear 3.80ish.
06-09-2017, 04:46 PM
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Got on the phone today with John from Little John Motorsports and Dusty from PTC and after talking to both of them we have concluded what would be the best torque converter / 8th mile gearing scenario so I will be updating the original post with the Newfound data for everyone to look at
