Rear end ratio for boost
Thread Starter
On The Tree
Joined: Feb 2019
Posts: 157
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Rear end ratio for boost Just after opinions on boost at rpms, ive read some posts but a lot are more concerned with results at the track 1/4 or 1/8.
dodge dart 3800lbs
ls 5.3 862 stock heads,
btr stage 2 turbo cam
edelbrock intake , 1250cc injectors
bw s480 turbo , 1.25ar. 2.5"cross over pipe, 3.5" dump
w2a intercooler, turbosmart boost tee.
coan powerglide trans , dana 60 rear 4.10 ratio. 3500converter
terminator x ecu
I realise its a big turbo for the motor, and the rear end is very short ratio. starts building boost at 4200-4500 rpm in first hits 6psi at 5500.
only a street car, I will turn the boost up higher once I am happy with the tune or get my e85 setup.
how much difference will 3.54 ratio make . this is expensive with these diffs, with the gears it will cost about $1000 .
i was planning on turning the boost upto around 20psi , seems like with first i wont have enough rpms
dodge dart 3800lbs
ls 5.3 862 stock heads,
btr stage 2 turbo cam
edelbrock intake , 1250cc injectors
bw s480 turbo , 1.25ar. 2.5"cross over pipe, 3.5" dump
w2a intercooler, turbosmart boost tee.
coan powerglide trans , dana 60 rear 4.10 ratio. 3500converter
terminator x ecu
I realise its a big turbo for the motor, and the rear end is very short ratio. starts building boost at 4200-4500 rpm in first hits 6psi at 5500.
only a street car, I will turn the boost up higher once I am happy with the tune or get my e85 setup.
how much difference will 3.54 ratio make . this is expensive with these diffs, with the gears it will cost about $1000 .
i was planning on turning the boost upto around 20psi , seems like with first i wont have enough rpms
TECH Regular
Joined: Jul 2019
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I have 4.08 in my car and have driven it with 3.69s. The difference is there but not drastic. I’m changing my 4.08 for 3.2x if around 600hp or even 2.9x if make 700+. Mine is a twin turbo 5.3 and spool comes on way quicker than yours. I don’t have dyno or tune yet but my 4.08s are a joke on 3psi.
Your gears with late spool, I don’t think you’ll ever get traction lol. I’d go taller than the 3.5x
Your gears with late spool, I don’t think you’ll ever get traction lol. I’d go taller than the 3.5x
Thread Starter
On The Tree
Joined: Feb 2019
Posts: 157
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3.54 is the tallest they make. I realise lots of people use these and a lot higher but is that primarily for track work. Will there be a big change with street driving. Keeping in mind that the 4.10s make the car a lot more fun to drive around the streets with. (that's from putting them in lots of n/a Cars though)
just don't want to get a Dyno tune done or e85 setup for higher boost until I have the gears correct
just don't want to get a Dyno tune done or e85 setup for higher boost until I have the gears correct
TECH Regular
Joined: Jul 2019
Posts: 460
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I don’t wanna act like there isn’t a difference. It make quite a change when I drove on highways. Just for your late spooling turbo, I didn’t think would be enough. If that’s all you have then for sure do it. Your cars also way heavier so maybe it’ll make a bigger change too. Mine is 3200. You might need shorter to get you moving better.
Thread Starter
On The Tree
Joined: Feb 2019
Posts: 157
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thanks for the response,
I just don't want to spend the coin if I don't have to obviously lol, I get a lot of people sayin put low gears and it will boost a lot quicker, but I also realise the turbo is way oversized for a stock 5.3 with a cam for street driving. so potenitially that late spooling turbo is the result.
I just don't want to spend the coin if I don't have to obviously lol, I get a lot of people sayin put low gears and it will boost a lot quicker, but I also realise the turbo is way oversized for a stock 5.3 with a cam for street driving. so potenitially that late spooling turbo is the result.
TECH Enthusiast
Joined: Mar 2013
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thanks for the response,
I just don't want to spend the coin if I don't have to obviously lol, I get a lot of people sayin put low gears and it will boost a lot quicker, but I also realise the turbo is way oversized for a stock 5.3 with a cam for street driving. so potenitially that late spooling turbo is the result.
I just don't want to spend the coin if I don't have to obviously lol, I get a lot of people sayin put low gears and it will boost a lot quicker, but I also realise the turbo is way oversized for a stock 5.3 with a cam for street driving. so potenitially that late spooling turbo is the result.
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TECH Regular
Joined: Jul 2019
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Yeah idk if would actually hurt you if went to tall. 3800lbs is heavy. Put that 3.5x rear end in and prob make big change. I would assume too tall would feel like starting in 2 gears to high.
Worst case, put it all together and if it’s a slug till very end then get another turbo. Either way the taller rear end if going to be needed.
Im 3200lbs and gears are a joke at 4.08
Worst case, put it all together and if it’s a slug till very end then get another turbo. Either way the taller rear end if going to be needed.
Im 3200lbs and gears are a joke at 4.08
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Is that converter speced for a turbo build? I don't know much about a glide, but that seems like a pretty loose converter. Maybe it's because of the glide, maybe because of the size of the turbo. Generally on a 3600-3800# car with a turbo 400 or a 80e, I like a 3600 converter with 3:55-3:42's and a 26" tire, but that is 1/4 mile. I would certainly gear it differently for a 1/8' car.
Edit, sorry I thought the converter said it was a 4500
Edit, sorry I thought the converter said it was a 4500
Two things that come to mind, You can't really compare someone running a 4-spd overdrive trans to your powerglide, It would be better to compare similar setups since the glide loads the engine differently. You can also add tire diameter into the equation, If you can run a taller tire it changes the effective gear ratio.
This whole topic I kinda battle with myself. I know with a turbo, lower gears load the motor harder and it lights differently/faster than a high gear that multiplied the engine torque more... So both are fun/useful in the street in their own respects
Track car makes all that rhetoric irrelevant... select gear for the power and mph goals in the 1/8 or 1/4 or 1/2 mile that your planning on using the vehicle for
Track car makes all that rhetoric irrelevant... select gear for the power and mph goals in the 1/8 or 1/4 or 1/2 mile that your planning on using the vehicle for
TECH Enthusiast
Joined: Mar 2013
Posts: 502
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This whole topic I kinda battle with myself. I know with a turbo, lower gears load the motor harder and it lights differently/faster than a high gear that multiplied the engine torque more... So both are fun/useful in the street in their own respects
Track car makes all that rhetoric irrelevant... select gear for the power and mph goals in the 1/8 or 1/4 or 1/2 mile that your planning on using the vehicle for
Track car makes all that rhetoric irrelevant... select gear for the power and mph goals in the 1/8 or 1/4 or 1/2 mile that your planning on using the vehicle for
Thread Starter
On The Tree
Joined: Feb 2019
Posts: 157
Likes: 1
After switching to e85 and playing around with the timing and fuel setups, hitting 7-8psi now at 4000rpm , that's from a rolling start. only a street car. I was pretty impressed. must be losing some boost possibly through the cooler or just the pipes too large , has a 7psi spring and I have turned my boost tee up a fair way to get to that.
that 7-8 is measured on the intake manifold with an autometer vacuum/boost gauge.
that 7-8 is measured on the intake manifold with an autometer vacuum/boost gauge.
Thread Starter
On The Tree
Joined: Feb 2019
Posts: 157
Likes: 1
Back on this one again , was on the highway a bit over the last few weeks , and sitting on 3900rpm bit annoying.
how much of a turd around the street would it be with a 3.23 or 3.55 gear ?
ready to make a switchup
how much of a turd around the street would it be with a 3.23 or 3.55 gear ?
ready to make a switchup
I'd go 3.55 and it'll probably be faster. Take a read here. Just made this recently and some good posts in it.
https://ls1tech.com/forums/forced-in...lly-click.html
https://ls1tech.com/forums/forced-in...lly-click.html
Thread Starter
On The Tree
Joined: Feb 2019
Posts: 157
Likes: 1
firstly I would like to say I added another muffler so car is significantly quieter.
So finally after getting a set of 3.55 motive installed
they were pretty loud whining.
got them done somewhere else , significant improvement but still a bit crap. ( could be bcoz of the extra muffler now more noticeable)
bigger problem
car seems much much slower , same eboost2 settings, only makes 6psi by 6300rpm , made more with the 4.1 gear and got there much quicker.
the muffler is a 14272735-78
although seems like wouldn't do much , it sure quietened the car a lot , so could be a big restriction
still needs a dyno tune , but off the terminator x and some street driving sure went good before .
( I will say though that because of the less revs , and less noise could be in my head but I don't really think so )
any advice thanks
So finally after getting a set of 3.55 motive installed
they were pretty loud whining.
got them done somewhere else , significant improvement but still a bit crap. ( could be bcoz of the extra muffler now more noticeable)
bigger problem
car seems much much slower , same eboost2 settings, only makes 6psi by 6300rpm , made more with the 4.1 gear and got there much quicker.
the muffler is a 14272735-78
although seems like wouldn't do much , it sure quietened the car a lot , so could be a big restriction
still needs a dyno tune , but off the terminator x and some street driving sure went good before .
( I will say though that because of the less revs , and less noise could be in my head but I don't really think so )
any advice thanks