Hey all I need some help figuring out my car, I'm making all kinds of power but just cant get it moving.
Since switching to the new 305/45/17 from the 315/35/17 I have lost ET and Trap speed the tire is about 2" taller which is a no brainer on the times loses. I really like these tires so I need to figure out which gear to run and where to restall to.
current gear 327
Current Stall breaks lose at 2900RPM and 5HG still in Vacuum its supposed to be a 4 k stall but surely don't reflect it. I cannot build and boost off my current stall and I want to stear clear of the T brake.
Any help figuring out the right gear and stall will be great.
I think you need it restalled. A converter will make or break a turbo setup. Get a set of 15s if you want better 60s. As far as what gear, not sure what you are planning on trapping or what you rev to. Gear it appropriately to be just under your rev limiter in 3rd right when you are crossing the line. Since i went to 28s, i might actually get some shorter gears and go from 3.55 to 3.73 or 3.90. Im not even close to the top of my limiter at 135 mph with the 3.55s so i could only imagine what you are with 3.27s
The restall point is what I am trying to calculate as well as the gear ratio. 327 suck ass on a turbo car, I am about at 6350 at the 1/4 miles mark with my gears and my car is built so I can go to 7K.
I am on the Verge of 410's and a restall unless someone can offer a reason why not to.
305/45/17s are 8.2% bigger than 315/35/17s. To get back to where you were with the smaller tires you will need a gear that is 8.2% lower. 3.55/3.27 = 1.085 - 1.000 = .085 or 8.5% lower. https://tiresize.com/comparison/
I don't know anything about stalls but it sounds to me like you might want to go to a 3.55 gear.
You need a "Transbrake" and keep the gears and tires.
My quickest pass ever was with 28" tires and 3.27 gears.
Your slow because you cant launch.
My tires break loose before 2900rpm without the transbrake.
You can hear my tires spin in this video before I hit transbrake button.
My car leaves like a snail all the time ive got to find some sort of common ground here. Something just isn't right with my gears and converter. info I gathered today was
I have never seen any conclusive data on why turbo cars need a numerically lower gear than a PD car, but the best theory I have heard is that the extra load on the engine makes it go through the RPM range slower, giving the turbo time to spool and stay up to speed.
If you had a PD blower, then your rotor pack RPM would be a fixed ratio of your engine RPM speed and the equation would have 2 variables like you originally mentioned: gearing and stall speed.
However, because turbos are gas driven and take a certain amount of gas flow to turn the turbine up to speed, another one is added: time. When you get a car up on the brake, it holds a certain RPM and exhaust gas flow for an extended time, forcing the turbine up to a speed that it normally would not achieve until a higher RPM when you are relying on the engine RPM rise through the gears alone.
So with that said, it's true that you might have a less than ideal gear ratio or stall speed, but you are not going to get that big single to launch like you want without a transbrake. Your exhaust just can't move enough air to get the turbine going. I've seen your work and I'm confident that you can swap out that valve body and wire up a brake in no time. I'd just go for it. I know this issue has been bothering you for quite some time.
Most of us call a "numerically lower gear" a higher gear. I don't have a turbo but after economic turbos came our a few years ago the turbo drivers started talking about their cars needing a higher gear. We have enough turbo drivers on the forum now that there should be some evidence as to whether that is true or not.
This is what gets me a bit confused. I thought turbos made full boost around 3500 rpm. It would seem that if you could hold it at 3500 rpm a little before launch you would be at or near full boost. And if you are driving an automatic then you would need a stall that allows this. I suppose the thing that would stop this is if turbos will not spin up without a load, but I've not heard people say that before.
P.S. I have never been interested in turbos so I've not done a lot of reading on them.
Cruising rpm doesnt matter. You have a lockup converter now. Your converter would need to be super loose to build boost on the footbrake. Where does your converter flash to?
We all have goals and want to reach them in a certain manner but the T brake is not an option for me.
I want to get around 5PSI at launch so I need to figure out which gear and how loose the stall needs to be to get me there. I want to do this with stall and gears. I'm not trying to launch at 10PSI 5PSI will be enough to get a good launch.
I suppose I could just settle this with a 100 shot of No2 at take off and call it a day and enjoy cooler AIT;s.
Pate, are you running an auto valve body? If so and you wanna keep the autoshift, there isn't a reliable transbrake out there for autos hint anyways. There are guys footbraking 1.2/1.3 60s without a problem. It's the converter. Get a hold of Darren birch and talk to him.
If a stall isn't an option, then a really loose converter is going to be your best bet on building boost at the line. I don't know if you will be happy with the converter slip you are going to see, though. Maybe if you lock it at the top of 2nd gear and keep it locked it would work, not sure.
All jokes aside, if you are dead set on having a footbrake only street car, a PD blower would perform much better than a turbo. You would probably have money left over after selling your turbo kit as well.
Transmission is my kryptonite I have pulled over 100 transmissions which is why I absolutely hate it Lol the smell of transmission fluid just pisses me off for some reason.
Much easier pulling the transmission than the engine.
Should've sent the converter out when you had the engine out.
I thought you had already had it restalled once.
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