How to Choose the Correct Gear Ratio for a Turbo Car? Tech Tip Tuesday
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- Опубліковано 8 вер 2024
- In this Tech Tip, Doug talks about choosing the correct gear ratio for a turbo car.
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Can you do a video explaining transbrakes? How they work and how to use them. A video on choosing torque converters would be awsome too 👍
X2
I down for a converter video for sure
Your converter builder chooses your converter based off your build. You don’t buy a off the shelf converter if your trying to go fast. Too much into stator blades/pitch size for your average person to spec a proper converter based off a UA-cam video
@@nsboost I'd for sure call the manufacturer to choose the converter but a basic understanding would help alot
Transbrake is stupid simple. It is a solenoid that activates the reverse band. When you activate it, it holds the transmission in reverse and forward gears at the same time, allowing you to build boost and "stall" the converter. When you let off, it simply lets all the energy to go into the forward and deactivates reverse.
The stall on your converter will be based on your car weight, horsepower, torque, and drivetrain setup. There is no magic setup, and all the fast guys have tried several before finding what works, and then they add power and have to change it again. Think of it as a slipper clutch, it can multiply torque, slip up to a certain speed, and it makes a ton of heat while it's slipping!
This was perfectly explained Doug.
This has always been an over sight for so many people.
If you could do a safety check list that you do for a racing season, it would be helpful for a lot of people.
My 1st drag week in 2017 I had 3:73s and it was horrible on highway for the long stretches to checkpoints. I have then switched over to 3:42s. Much more enjoyable on open highway. I didn’t mind dropping 2 tenths on hot days, but still ran deep 10s with the LSA on cooler days. Another awesome tech tip from Doug!
This is a reassuring vid for guys like me who question the "longer is always better" argument with turbo cars. So many variables besides rear end from engine size to number of gears and most importantly, what turbo/turbos are being ran. If you have a 4.8 or 5.3 redlining at 7k and you're running a single +80mm t6 turbo that won't spool until 4-4.5k than yeah you could definitively benefit from longer gears but if you're running a 70mm t4 that hits full boost right away you just gave yourself another 1-1.5k of rpm per gear. It's all about having the proper setup.
Well explained Doug!! Simple and to the point.👏 Hope your Nova comes back better than ever. 💪💪
Doug, can you talk about your suspension geometry, tire setup, or whatever other wizardry you've put into the Nova that keeps it so level launching out of the dig. Like there's no ass end squat, no crazy wheelies like Jackstand etc. Your car really just shoots out so flat like a missile. It's far better than really any of the other cars that I've seen you against in your class. Truly a thing of beauty. Shewwww Buddy
Tuning with c16 in boost. Plenty of info out there on e85. But there’s a ton of benefits of c16. Maybe explain why someone may want to consider gasoline instead of ethanol and then how to tune for that optimally.
thanks Doug, i had been suckered into the lug your turbo car but always doubted it for all the obvious reasons you pointed at. currently running 3.42 will now go with the 3.7 that i had planned to do.
Have you done a video on transmission selection using a powerglide or a 2-3 speed 400
3.55 rear gear in a T5 five speed foxbody mustang (72 mm turbo) with a 26' tall tire lands me at 2300 RPM at 70 mph on the highway but still lets me rip gears and launch great. Not the best roll racing combo for those real highway speed rips but its great for in town and at the track which is 90% of the cars life.
I’d love to get your thoughts on exhaust wrap. Even if it’s a video about why you don’t use it.
Not a tech tip question but I was wondering if y’all could go over what it takes to make a irs GTO full ish interior to run a 5.5 or better in the 8th. Horsepower, suspension etc. a lot of gto owners really didn’t think it was possible tbh.😂😂
I’m not a GTO guy but I also think it is impressive
@@mikemorris4409 I have so many questions lmao
@@mikemorris4409 and it STILL has front sump. Wtf front sump irs gto in the bottom 5s
I love your tech tip tuesdays boys
Thanks Tom!
Very informative! GOOD STUFF!
Looks filmed before race week!!! Glad you're ok man,,, we love you brother!!!! Do a safety tech tip Tuesday....
Great content thanks for sharing, very informative
I’m running 4.10 in my 2015 GMC Sierra single turbo precision 7675 puts down 650whp in low boost 11psi and runs pretty good as i wanna to be I’m not drag race guy only rolling from 60mph now I’m thinking to switch with 3.73 because i will turn up the boost to 17-18psi after i build my 6l80 trans level 4 circle d
I very much Appreciate these videos !
This team is killing the information sharing game and making all of us better and faster !
Thanks again. Any value in a discussion on driveshaft material/size and u joints for various power levels?
I would be interested in hearing your thoughts on how to size rear tires for drag racing. Presumably one would want the smallest tires that would provide the requisite traction. Is there a rule of thumb? Specifically, I am building car that will be ~2000lbs with ~600HP- can I get away with an 8" tire?
stock boosted k in an eg?
@@pullena09 Tesla large drive unit in a MK2 VW GTI
Ya I think the lower numerical gearing is just more fun/easier to drive on the street
Good video. A deeper dive into SLR, weight and 1-2 leave would have tied into this topic well.
What's the best gear for a highway using a two speed power glide
A video explaining starting line ratio and how it affects the car would be nice
Always love your tech tips. You and your guys are awesome and build such high quality parts.
Da, humidity, elevation, weather related tuning for the track.
What is the best cam setup for a daily driver.. Meaning what's the best for getting the most amount of power for racing but won't kill the fuel milage on the highway
Can you do one that discusses the pros and cons and legality of using air suspension in a race car, drag week car and street strip car? There's not a lot of info out there about it but I see guys like Chris Alston pushing air suspension stuff. Thanks
It's a lot harder to setup correctly. Coil-overs are so easy, not many will want to mess with air.
Not to mention leaks, and needing a tank and compressor to keep it optimum throughout the day as temp swings will push the car up and down.
Hey!! Do a tech tip on 2 steps!!! Explain what they are and what you need to put one in a vehicle!!
Rev limiter on a button. Push the button and hold the gas to the floor and it cuts ignition where ever you set it at. They're typically used in conjunction with a transbrake, so you'll hit the brake, hit the 2 step, hold your foot to the floor, and when the light goes green you let off the button releasing the trans brake and 2 step, which lets you launch and build to your full RPM.
A lot can be programmed to turn on with the transbrake, leroy runs a clutch switched one, etc.
It just allows you to launch at a predetermined RPM every single pass, and adjust that launch for track conditions.
Excellent Tech Tip Doug!
I ran 388s in a 63 Dodge Power wagon/318 and it ran 10s all day long. The only issue was top end speed, but 10s in a big ole four door, 4x4, back in the early 80s was unheard of. I am curious to see what you think of the 389s and how that ratio (combo with trans) works out. On my truck, top cruising speed was 75/80 because the RPMs were just too high for long drives (yup, have another set for the road vs the track).
I ran all motor, but the only real difference with turbos is adjusting those shift points according to the peak boost, so you don't free spool and maintain the power push all the way through the run.
Excited to see how the rebuild unfolds on the Nova, if you do try the 389s I think you will definitely exceed 200, maybe even 205, depending on the trans gear combo. Guess we'll see what develops.📀👌🤙
Just in time, looking at them this week
I understand everything you are saying!
👍🏽on point with this video, what's your thought on tapping compressor housing for boost control. AKA Street/strip car
Anyone know if tapping into turbo housing for boost control is good with a controller vs spring pressure.
Thanks, good subject matter.
Maybe times and lingo have changed but you keep saying lower gear when you mean higher unless you mean numerically lower. I’d be curious what you have found with converter efficiency vs a gear ratio change before and after at the same rpm and tire.
Agree. Doug your comments are incorrect regarding lower vs higher. A lower gear ratio is higher. Ask moser. Curry. GM. Ferd. Hell even Toyota!
It can be said both ways lower numerically vs lower gear. Probably more geographical and who you hang with
Big bore short stroke low gears lots of RPM for the win
How Is a welded diff bad compared to a spool for a race only application? I’ve heard, reliably better with spool I’ve heard the obvious tire wear.. please enlighten us on different lockers. Thanks guys I love the show and I look forward to having motion raceworks on my 65 galaxy 2 door sedan drag car!!
Great information thanks so much
Info is definitely 👍
This was a great tec tip. I have been looking for just this information. Thanks
Thanks Kenneth!
Good to hear Dale! Glad we could help out!
How to get a car to launch and how to make adjustments to suit at the track
Great tips. Why use nitrous to spool a turbo up faster?
I'm having fun planing the way to build my daily into a nice driver for when my daughter barrows my truck, and for the way i like to drive combined with what i will be doing with the truck.
Beach driving will be mostly my stomping grounds.
Bogging in deep sand.
Truck is tuned, next week is a dyno run, for documentation on future upgrades.
Next will be gears, my tuner suggested cold air, and intake manifold, 3rd gen, mine is first gen coyote, but i would like more gearing for the sand, so i was thinking 3:89, 20 inch rims, with 275s, that combo should roll me off the stop light with the quickness and be a nice daily.
Then cold air, intake. and maybe that will be 400 Hp, high 13s. No, not really, it turns 200k in 50 miles and i am told it will burst into flame, explode form a black hole and consume the earth at 200k. Going to be interesting.
With modern dual clutches that shift in milliseconds can that type of application be applied to the drag strip? Low to get you out of the hole then over a series of shifts say 4-5, higher gears to keep from running out of gear at the end of the track. Is that possible?
Lets see those IRS Drag tech tips after you guys were so successful with Andy's car
Great video I did all wrong building my 69 Chevelle in the late 90s
I feel like back in the early to mid 90's anyone that had a Chevelle or Nova or Mustang etc. that was street racing the quarter mile, it seemed like it was just a "known thing" that everyone was running 410's or 411's. At least that's how it was here in New England. Nobody had less than 383's and it was never questioned.
It depends on your engine design and displacement. Long high velocity runners will make the power in a lower RPM range than a short lower velocity port. A small displacement engine needs more RPM to make up for its lack of torque compared to a larger displacement engine. Forced induction allows you to run a taller gear than a NA combo, because it is making more torque at a lower RPM. The NA LS engines are running more gear than you are boosted, they have to because they don't have the torque you have, and you are going a lot faster through the traps. 4.88 gears at 170mph means a lot of RPM.
Then you have the issue with traction, you probably don't notice this much since you can limit torque on the bottom by limiting boost, then ramp it in later in the run. Running my torque monster big inch Pontiac engines it becomes apparent quick. I can run within a tenth using a 2.41 gear as a 3.55 gear, and a 4.10 or deeper loses mph and runs a slower ET. A 3.70 loses mph and occasionally runs the same ET, but often is slower. Where the problem lies is that with all that 600ftlbs of NA torque just off idle the wheels want to go a lot faster sooner with the 2 something ratio, the limited mph of the taller gear actually helps it hook better in some cases. With a 2 something gear a full track burnout is simply whacking the throttle from idle and not holding the brakes, because the vehicle never catches up to the wheel speed. With the 3.08 to 3.55 the car catches up to the wheel speed sooner.
Yeah my engines are somewhat of an extreme example. Positive displacement blowers and other forced induction can act like my engines, even with smaller displacements, but making a lot more power because you are throwing more air into them. The thought process behind the boosted engine and a NA Pontiac is very similar though, in that you need less gear because you become RPM limited and have plenty of torque to push the taller gear.
Why does the Pontiac 455 and larger stroked engines need a 3.55 or taller gear? Because they are long runner, high velocity ports, which make all the power below 6500rpm, or under 6000 with iron heads. 550ftlbs at 2000rpm is crazy easy to do, and its just as easy to still be making that much at 5000rpm. If its all over by 6000, then a 5000 stall and 4.56 gear is going to slow the car down, even in the 1/8 mile. That is a NA pump gas engine with garden variety parts, not full race stuff. On E85 you can make even more torque very easily with compression.
In the 90s I was rather broke, so running 11.40s with a 3.08 gear meant I had to put a cage in my bracket car that I could not afford. 11.99 was the cut off then. I only had $5k in the entire car, from buying it, to rebuilding a 455, and buying some tires. So I swapped a 4.10 gear in and that slowed it to 12.1 to 11.8, and rather than running 120mph it was running 110, due to the fact it was out of RPM at the 900ft mark. It did not pick up in the 1/8 going to the 4.10 either, but ran rather consistent 7.70s. That made the tech guys happy even if I was zinging my stock rods at 6000rpm for 400ft of the track.
What happens when you throw 14psi at one of them? 1200ftlbs through the entire RPM range. Contemplate that a bit... do the math. If you are moving the engine too quickly through its RPM range where its making torque like that, you are wasting power that could be utilized to move the vehicle. You don't need 9000rpm when you are making that much torque between idle and 6500. You want to start the run where the engine is making enough power to move it, and let it work in that RPM range, which is true for the tiny 9000rpm engine or the 3000rpm diesels. Throwing more gear and stall at it is not always the answer, you have to match your engine's output, and balance power with traction.
I know, this all sounds like bunk to someone who has always raced chevy small blocks. The chevy designs are not known for low end torque, they are RPM engines with big lazy short length ports, and that makes them a high RPM engine. You have to spin the snot out of them to get power from them... until you slap on a 6-71, then it acts like a larger BOP engine, makes torque under 3500rpm, and thus requires less gear to actually move the vehicle.. You might think 400ftlbs at the peak NA is a lot, to me that is part throttle.
When you ditch the factory LS intake manifold and put on one of the intakes like Cleetus uses, you turn it from a long runner engine into a short runner. Even under boost its going to affect where it makes torque. Shove more air into it with a steady boost curve rather than a rising one like a centrifugal blower, and the torque curve will be a higher number but mostly the same shape.
How long your intake port runners are and how fast air flows through them will help dictate what gear you need to run behind it.
What rear end gear do you recommend for a RCSB 4100lb street/strip turbo 5.3 with a 6/700whp goal (Will be going 4l80e)
Don’t mind going 2400-2800ish rpm at 70mph
Have stock 3.42 at the moment
565 blown bbc, 950 hp, 850 lb/ft and that’s @ 3,500 rpm lol.
In a 4,800 lb car, with a 28” tire. Thought I better put some gears in this whale… went with 3.89’s… had the trans built with a 3.47:1 1st gear!
Problem I have with that is, it won’t shift fast enough to stay off the chip at 7K. Even if I’m rolling 35 in 2nd and nail it, straight to the rev limiter in 2nd! So I’m ordering a 3:25 and hoping that’ll help me.
My rule of thumb for any gear ratio, is only go as low as you need to. Too much gear and you’re wasting energy from the engine spinning the driveshaft and not going anywhere. The less rpm the driveshaft spins, and the more rpm the tire spins the further and faster the car moves if you have the power to overcome the gear…
Setting up a basic 4 link and what driveline angles should be?
I second this one for a tech tip tuesday
google Kevin Wilson SBC he has a series on suspension setup including 4 link
Is there an optimal or maximum distance away a dome sensor can be from the gate it is referencing?
For example, if I wanted to use a rife Triple sensor for map, dome, and cylinder pressure...all three of these are currently spread apart in my engine bay. Using the triple sensor and harness would be extremely easy in terms of wiring but would mean that at least one of the sensors ends up needing a much longer hose/reference line. At what point is this too far away? What effects would a longer reference line begin to have on each of these things? Or does pascal tell us that it doesn’t matter since we are only dealing with a few feet of change at most?
I personally think the proper gear ratio, makes it spool faster. Unlike the old advice of running a super low gear ratio to load the engine down. Rolling into a properly geared turbo car on the street should spool super quick.
I think proper gear ratio is the cherry on the top..but honestly how does a spooling turbo know what gear ratio u have? Proper fuel and proper timing in those affected cells of ur fuel/timing map are what’s gonna lite that turbo up
@@bebetekracing2412 because you would be at the proper RPM moving more air and more exhaust to spool it up, instead of loading the motor down at a lower RPM like the old timers say
preach it brother !
wait...so what my 4:56 aren't good for the 1/4 ? 🤣🤔😅
Knowledge is power ……
Good Talk
But doesn't weight also play a big factor in the selection? I was thinking of 3.50 for my 2200lb strip/street car & ik that nova has to be alot heavier than that.
I'd still like to know about that badass rear leaf spring set up on that Nova. :)
Yes! This! I posted a similar comment. The way Doug's car launches so flat like a missile is some serious wizardry. Like the polar opposite of Jackstand doing his wheelies lol. I wanna know what that suspension geometry is all about!
Caltracs bars
Got it! Clear as Mud
Doug, do you use a small pinion street ring and pinion in the Nova?
Guys, will you please start supporting the G3 Hemi platform !
Great information, so my crownvic has a 3 27 gear and my shift point is 5750rpm so what rpm should I be at the 1320 ft. mark? And I have 27.18 overall diameter tires. I plan on getting twin turbos soon
I don't know about you but I'd replace the four speed transmission with a 6R60 six speed transmission if I can shoe it in. There are limitations to top end and acceleration with the AODE, 4R70, 4R75 family of transmissions that I'm not comfortable with.
I know it your car BUTT I wish it still looked that good now! BUTT I know you'll have it back looking as good or not even better! 👍
So, a race car with a turbo is still a race car. This video completely defines the overthinking things that is the bain of my existence.
So a 389 is good for a 8th mile no prep car … twin turbo LS combo?
Can you do an investigation into what went wrong with your Nova engine and how to avoid it happening to someone else
They already did. Ball valves were junk
Already have, ball valves were junk causing fuel flow issues making it run super lean. Things got melty very quick and boom, the rest is history.
What ball valves were bad? - I understand vehicles- I just don’t know where they would use a ball valve
@@nicholastaylor1546 ball valves they had on the fuel tanks to swap between race and street fuels.
I'm not really sure anything was disproven because I've only heard people talk about this for H pattern cars on the street and after owning one I agree with that.
As for racing. I don't see this as a myth since this was going around years ago before turbos were being improved through the mid 2000s. So really, technology and development has progressed.
If you wanted to run a glide but still have it a street car, like to do race week, could you switch center chunks at the track or is a over drive unit something you would need. Just thinking about high stall applications and the trans getting hot on drives.
Either switching center sections or running a gear vendors would work. Keep in mind the glide won’t be any diff than a th400 as their high gear are both 1:1 ratio.
I have a 411 in my turbo car I’m going to 355 gear I run 1/4 mile
My car was 380ish horse it was great with 3:73's but now with a whipple supercharger and 700 horse I sort of want my 3:33's back..
What gear ratio Calculator do you recommend .
I use the TCI calculator or checkout Wallace Racing
So how does the HP loss between gear ratios work? 4.11's eat more pwr than a 3.70?
Great tip 🙌 What type of case is good 9 inch rear end
Moser, Strange.
9" actually suck, the offset pinion saps a lot of power. They are quick to change gears if you have spare 3rd members though. If you're just going to set it and leave it, there are plenty of other options out there that will work just as well.
Do you not run a Gear Vendors OD unit in the Nova?
Finally someone agrees
Techtittuesday
Great tips, sad to see the nova whole.
I just keep my foot to the floor tell it doesn’t go any faster
I went from a 4.56 to a 5.14 for 1/8 mile and it didn’t help me at all. I have a NA Big Block and the wives tale is that they don’t like high numerical gears. I have a 3.73 now…
Anyone else get distracted watching the dog !!!!!!!
Martin--I actually lost track of what Doug was saying. That's funny.
How about you show everyone your engine? Was it just the block said F/U, or did something else let go first! Like you said, you put the rear gear ⚙️ in the car that will give you the right RPM for the mile an hour & tire size @ the finish line 🏁! Moroso slide rule always very close! 👍🏻👍🏻👍🏻👍🏻
So you have 3,70 and a 1/4 mile trap speed of 194 . What is you finish line RPM ?
Plugging it into a calculator it says around 8200rpm
Correct
Sweet Clip.. I enjoyed it as always.. But How do we fix Stupid??? 🤣💯👍👏🤘
Does the same ring true for a manual car?
Yes.
No Doug! The internet says to put a 3.08 gear in all turbo cars and trucks 😂😂
So your saying gear is gear, no matter how the power hits it, imagine that 🤣
Support 🇺🇲
Nice appearance DOSIER. Anyone? Mhmm Matt you Liar! LOL
Do a video about adding a burst panel. And then make us a retro fit burst panel, so I don’t have to replace my low pro Holley
I love my 3.08 just because I love street driving it too much, had 3.73 and only would cruise at 63 mph with a 28x10.5
I agree with you! I had 3:73s with my th400 and it was horrible on highway. I now have 3:42s and it works good for me on the track and street. I’ll probably go to even more street friendly gears next time. I also run 28X10.5. I’ll sacrifice a few tenths for a more enjoyable mostly street and limited strip car.
@@brocksutliff8782 I still 60ft and mph decent at the track, consistently doing high 1.30 60fts and high 120’s in the eighth so I’m happy with it
im guessing video is record befor mountain week Crash
The very obvious to me. A shorter diff ratio for 1/8th mile. As well as a shorter first gear so at least a better 60 foot.
SO get rid of bloody 2 speed trannys and go at least 3 speed. And a T400 is stronger to start with.
With a better first gear you can pull a taller diff ratio for the 1/4.
All that slipping the hell out of the powerslide is lost energy. I think Cleetus proves that using 4 gears. On a manual gearbox,, not the girlie autos!!
Unfortunatly the back drop shows the lack of immediacy of these clips. Your poor Nova is at the doctors at the moment