Orr89RocZ

iTrader: (20)

15 years of experience but you dont understand that the question you pose in item 1 about manifold pressure is called a map sensor which most engines have, or at the very least a maf sensor which some can automatically adjust for changing atmosphere....or that closed loop o2 thing....wow

QwkTrip

iTrader: (22)

Next time I see a 2.0L Nissan Primera I'm going to wax the poor bastard.

mk1431

just what i thought..... a class of my own

skinny z

My point exactly. What's more, with the car already in motion, the effect of weight transfer is diminished (simple physics). Combine that with the reduced coefficient of friction between the tire and the unprepped asphalt, and there you have it. Tire spin. Traction control in our era of vehicles is provided solely by modulating the right pedal.
Hell, even with my measly rear wheel output, I can still burn up my ET Streets to the top of 2nd gear (700R4).

Kingtal0n

What are your questions regarding these things, manifold pressure, maf sensors, O2 sensors, closed loop. I am familiar with all of these terms; where does it show that I am not? I have written an auto tuner on this very forum for an ECU 15 years ago in fact, and it used a closed loop operation algorithm for which an array of stored air/fuel ratios are logged and compared to the users throttle/map input for auto-correction. Do not throw dirt I have been nothing but helpful.

1986Z28OWNER

iTrader: (1)

"Helpful"

Kingtal0n

What you take away from a book of information, could be quite different than what someone else can take away from the same book. Just because you cannot make heads or tails of something alien information or new, (hey guise, look through my telescope and see the stars... Whats that? You want to stone me because you know the earth is flat and I am spouting heresy? Oh dear...)

heres a TPI engine, the first one I ever 'tuned' (over 15 years ago) although it arguable tuned itself

http://vid9.photobucket.com/albums/a...psbj6zzsfl.mp4

this was my car and eventually twin turbo. After a blower, of course. And this, coming from carb as well. I have made many mistakes... only trying to help others to avoid them.

dbrochard

iTrader: (3)

That's an interesting perspective...


I guess I see what you mean because pressure changes depending on alititude, but not really
I get that you feel you have a lot of knowledge that could help the original poster, but I think you are sharing a bit too much info that isn't too helpful to him. I'm sure that he just has a bunch of little kinks to work out

Kingtal0n

what I "mean" is simple: control the atmosphere, with a dial, from within the vehicle. Even if a vehicle doesn't have a turbo, you should think of it like it WILL have a turbo soon (because you are going to add one). Turbocharging is "next on the list" so think of your plans as if the vehicle is turbo. Hold that dear unless there is a significant block to doing so. It is both contradictory and connected in many interpretations, and the reason it exists is to get you thinking about how similar atmospheric "turbocharging" and actual turbocharging really is. An atmospheric engine can be thought of as having an imaginary wastegate which is stuck to one particular boost pressure. It is "turbo" by the atmosphere, and the gate controller is stuck to one setting and the dial is missing. We want to re-connect the dial, add it back to the engine for control.

That is the basic meaning. All engines get "pushed on" by the column of air molecules extending some distance above Earth, and without a dial you are at the whim of the environment. The year is late enough that every engine where practically applicable should have a turbocharger, with non-turbocharged engines being simple "stuck wastegate" situations "on paper" in between a full vacuum and however much pressure you think you desire. Think of an infinite range of pressure scalar quantity, and then pick one exact number as "atmospheric" and call it a "naturally aspirated engine scalar pressure quantity" which, ironically is not actually a constant either. It the same as a turbocharged situation which is fixed at that same single pressure number (and models every other infinite pressure quantity as a possibility if we can un-stick the imaginary wastegate). Another point to consider is that pressure is not constant on a running engine, even when atmospherically aspirated, exhaust gas pressure rises and falls, pulsing with the engines rotating nature, whether there is a turbo in place or not. The only time the pressure is sitting strictly at atmospheric is when the engine is off, and even then it is still being "pushed on" by the atmospheric column of air molecules, like a giant air compressor as gravity exerts its influence.

I see what you might mean about extra info, but a book or link to a book that contains everything is even more "helpful" yet contains more information, I do not see the difference between typing a book worth or part of one as opposed to linking an entire article or series of works. Truly helpful information will make all the vehicles you can possibly drive faster and more economical if possible, a foundation "roots" thinking that will favor the individual. The word 'traction' implies some form of performance output from an engine, and the first step if possible in anything that has to do with power is to install an atmospheric control dial, preferably driven partially from energy in the exhaust system. The dial is now a "traction control device" since lower settings improve traction, it is one form of applicable traction control to mention boost controllers when discussing traction, and I have mentioned drive by wire solutions as similar examples (you don't actually need a real DBW it was just an example to show that limiting throttle body movement = traction control). All of these are features which REDUCE power output to provide reliable street traction with poor tire selection. Affordable available options that could be considered if there are problems in the chassis, for example, at least for the time being while the chassis is getting fixed up. It is supplementary to, not opposed to, what you are saying is necessary in the suspension and minute details, every chassis needs tweaking in the suspension components and billions could be spent against that aspect. I bring the cheapest/easiest solutions first, is all as supplementary, as needed basis info, apply where necessary.

QwkTrip

iTrader: (22)

Bob: Do you know the answer to 2+2 = ?

Kingtal0n: It's 5. Math is used when baking.

Bob: It's 5? That doesn't seem right.

Kingtal0n: Yes, 8-3=5. You need 5 cups of flour to make cupcakes.

Bob: I'm not making cupcakes. I'm doing my math homework and I just need to know what is 2+2 ?

Kingtal0n: Oh, I see your misunderstanding. Cupcakes need flour.

Jim: 2+2=4

Bob: Thanks, Jim.

Kingtal0n: You can't understand 2+2 without first knowing that paper is needed in order to write down the recipe for cupcakes. blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah And that's why you should keep fly strips on the ceiling in the same room as you store the flour. Otherwise, you'll never figure out the solution to 2+2.

Bob: I got the answer, it was 4.

Kingtal0n: I can predict 2+2 because I know cupcakes use flour. I have spreadsheets that are able to take any number you have and convert it to 5, which is the number you need. So even if you're wrong, I can make it right. It's really quite simple if you understand the blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah Spatula random questions: Should you stir cupcake batter with an old fashioned wood spatula, or modern high performance silicone spatula? blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah The Chinese can't make good cupcakes because they have a lot of rice.

Bob: Shut up.

Kingtal0n: I'm an expert and can help you with this. I have 15 years of experience subtracting 3 from 8. blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah

----- 2 YEARS LATER -----

Terry: I'm going to use the search engine at thirdgen.org to find out what is 2+2

*clicks the SEARCH button*

Terry: What the... ????

redneckjoe

"Summed" up perfectly!

Night rider327

iTrader: (13)

Kingtal0n, I can tell you have knowledge but I think you are over doing it and going too far from the question at hand.

I mean no disrespect from this but do you have Asperger's syndrome? I know someone with it and he does that same thing.

MoJoe

iTrader: (5)

We have a winner!

2+2=5, but only for large values of 2.

skinny z

If nothing else, this is all thoroughly entertaining.
PS. I would never turbo an engine. Not my cup of tea.
And considering that this thread have completely swerved off the path of the original question, why is it that the fastest dragsters in the world use superchargers?

Kingtal0n

because at that level it isn't about longevity, its about winning.

If you want to win the race you do anything it takes i.e. build a new engine each race and abuse the ****.

I am all about daily drivers with 500bhp and $800 longblocks that go 150k or so. Completely opposite thinking.

I like how he needed to make something up just to throw dirt. In case you need any math help, I am a math tutor for my college for several years and I Can help you with anything from intermediate algebra to calculus/differentials. I do it on the side as a hobby...

I really don't know, I was never diagnosed with anything because I never see a doctor. If I was, would it make others more understanding? Or just pity. I really dont want pity, I prefer the dirt and filth, the stones. It helps to be stoned amirite
you can think of it as: entertainment. At the end of the day, we laugh at the jokes, we hate on the villain, but we love the actors, and sometimes get some insight out of it.

Street Lethal

iTrader: (16)

Too many variables.

You are debating a boosted 2.0 engine with less weight to a naturally aspirated engine limited by, not only cfm due to the lack of supplemental boost pressure, but RPM. You claim the 5.XL engine as pathetic in comparison, but the 5.XL engine makes more torque down low without the need for the turbo charger compared to the 2.0 engine does with such compensation of air pressure from the factory. For starters, pull the turbo off of the 2.0 engine and suddenly the engine makes nowhere near what the 5.XL engine makes at a higher RPM let alone lower RPM which was never there in the first place with the smaller engine, so this tells you that the larger engine, despite not being boosted from the factory, will make more calculated horsepower. Weight has nothing at all to do with it, the problem with weight is that people have been focusing their efforts over the years on 500 horsepower with an already determined RPM peak, and gear ratio. The benefit of RPM in a naturally aspirated engine is tremendous, it is not uncommon to find high revving 302's running 10's naturally aspirated in a full weight Camaro. Why? It is because of the rate of acceleration, which increases with RPM. Same reason why a Supra shifting at 9000-RPM with less horsepower than say a new Corvette making more horsepower will trap higher. Simple science. The larger engine has the benefit down low, but down low is no longer needed with high stalls and higher RPM. Therein lies the difference between your 2.0 vs 5.XL comparison...

Kingtal0n

Not at all. What I proposed was a cost comparison, not an engine comparison. I typed: we want the largest piston swept volume (displacement) for minimum cost with high reliability at some peak potential for power.



More info;
So if you just throw out random numbers, 450hp and 3800lbs. How much does it cost to get 450hp reliable (or any number) for how many miles you feel like is considered reliable? Then find that cost, and find the engine associated with it where cost is minimum(which engine can support 450hp worth of trap speed at 3800lbs with reliable nature), it is a beginner's calculus problem to find the lowest cost for an investment in dollars. Lets try 450rwhp @ 3800lbs we can either increase power (but power is constant for this attempt) or reduce weight. If I can shave 1000lbs off of that, I can do the same amount of work with 2800 lbs and just 380rwhp ( we will 'gain' probably 80-100hp). Now find me the cheapest engine that fits a random 2800lb chassis reliably at 380rwhp. If we can use our camaro chassis, cut out 1000lbs and use a nearly stock "HCI" engine that would be pretty cheap. And reliable at a mere 420bhp(380rwhp). If I cannot cut 1000lbs out of my camaro then I have to find another chassis. And maybe this next option also has even cheaper options for engine selection, engines which come from the factory (i.e. reliable) already with a turbocharger, the comparison is fair when we are discussion strictly OEM engines since you are putting just as much faith in OEM parts around the table, which might not always be true. Japanese engine parts tend to be more like performance parts, with better controlled clearance and robust nature. GM recently is producing brand new engines with oil consumption issues in vettes, machine work related perhaps. We try to avoid these machine work issue, by using pre-tested engines (engines that already have 50-80k if possible, well maintained with history and track record of performance) it does not matter if 1.0L or 9.0L as all vehicles desire minimum weight if possible and reduced rotating mass for improved economy and low to moderate miles conditioning. Some applications call for reduced power and reduced engine size to maintain economy, it isn't always about peak power or maximum displacement, if a next engine size down has a better track record of reliability and I can still "meet" my performance goals power to weight ratio at a similar cost, that is common sense.

Orr89RocZ

iTrader: (20)

This is the best thread i have read in 10 yrs

Qwktrip you killllled me with the cupcakes

redneckjoe

Rockin in my 2.0 !!!

mw66nova

iTrader: (13)

i'm literally crying here from laughter.

mw66nova

iTrader: (13)

The limit is formally defined as follows:
limx→a
f(x) = L
if for every number  > 0 there is a corresponding number δ > 0 such that
0 < |x − a| < δ =⇒ |f(x) − L| < e 
Intuitively, this means that for any , you can find a δ such that |f(x)−L| < e.
To do the formal  − δ proof, we will first take e as given, and substitute
into the |f(x) − L| < e part of the definition. Then we will try to manipulate
this expression into the form |x − a| < something. We will then let δ be this
“something” and then using that δ, prove that the e − δ condition holds. Some
examples should make this clear.
1. Prove:
limx→4
x = 4
We must first determine what a and L are. In this case, a = 4 (the value
the variable is approaching), and L = 4 (the final value of the limit). The
function is f(x) = x, since that is what we are taking the limit of.
Following the procedure outlined above, we will first take epsilon, as given,
and substitute into |f(x) − L| < e part of the expression:
|f(x) − L| <  =⇒ |x − 4| < e
In this case we are lucky, because the expression has naturally simplified
down to the form |x − a| < δ! Therefore, since we know from the above
that |x − 4| < e, we can let δ = e, and we know that |x − 4| < δ. This last
point is very important.
We can now finish the proof:
Given , let δ = e. Then:
|x − a| < δ =⇒ |x − 4| < e
=⇒ |f(x) − L| < e
QED

skinny z

Psst. Your math degree is showing...

mw66nova

iTrader: (13)

maybe we should get back to the question at hand.

if you're sticking with drag radials, get some that don't suck (nittos suck). mickey thompson likely has a tire that will fit your size requirements.

if max traction is required, put a proper bias tire with a tube for added stability.

skinny z

Since you ask, what's your opinion on the new(ish) MT SS radial? While mine isn't QwkTrip's car, I'm looking for a street/strip tire.
https://www.mickeythompsontires.com/...tem=ETStreetSS

Orr89RocZ

iTrader: (20)

Right!?

QwkTrip

iTrader: (22)

Oh wow, 200 level math studies. That's what people in my field call basic prerequisites.

QwkTrip

iTrader: (22)

Ya, I had it down to the NT05R and the Mickey SS. I didn't think the Mickey would last long enough to get me through a summer so I bought the Nitto because I didn't want to buy more than one set of tires per year.

Although, there were some really good reviews on corvetteforum.com for the NT05R and some of those guys were making a butt load of torque with power adders. Although, a n/a stroker like mine is like a light switch when you hit the throttle.

plum92_camaro

Cupcakes!!! I haven't laughed that hard in a long time.

I'm still getting used to my car since the LS1/t56 swap, but I settled on 25 psi for the street with my 315/35R17 Nitto 555R's that are a couple years old. On cooler days (60*-70*) I can scratch them up into second and third. But today I tried a launch out on a back highway and the clutch slipped more than the tires! It was 90* with the sun cooking the concrete, tires were good a warm from driving.

Wider tires require less pressure to support the weight of the car. Don't be afraid to drop the pressure a few PSI.

Street Lethal

iTrader: (16)

Talon, you mean well, but what you're saying is overkill. He doesn't need all of that information, especially the way you are explaining it. An engine with more cylinders utilizes less fuel consumption per cylinder to make the same power, and that is the advantage. It will always make more calculated horsepower. The OP discovered the difference between flywheel horsepower and rear wheel horsepower when he dropped tire pressure and was able to hook, so now it becomes the matter of balancing torque control (spark advance). Try not to be that philosophical with your explanations...

redneckjoe, this had me rolling lol...

mw66nova

iTrader: (13)

the only difference between this tire and the original m/t radials are the amount of sipes on the tire to help with wet traction in the event you get caught in the rain. they work identically at the track and would be an excellent choice for an auto car.

mw66nova

iTrader: (13)

i lol'd at this too.

QwkTrip

iTrader: (22)

I have a mildly modified 3.5L Ecoboost F150 and I'll drive it any day over the 5.0L V8. My one gripe about it is the inconsistency off the line. You never know how much torque is going to hit the rear tires when you're trying to leave in a hurry. You just guess how far to push the throttle.... wait a moment... and then the explosion of torque hits. More than half the time you'll guess wrong and light up the tires. And you don't dare lift throttle or the boost will blow off and you'll have to start all over from the beginning again. Once I reached a certain power level with the Ecooost I just began using 4WD to launch because 2WD is too inconsistent.

What Cupcake doesn't know is that I used to have an HKE 1100 HP twin turbo LS stroker sitting in my garage for the Firebird. Good sense got hold of me and I decided I didn't want to die in a fireball wreck after losing control of the car on the street. The dream doesn't always meet with reality. You know, that s**** is for race cars, not the street. There is a practical limit to power on the street that is fun and after that the car drives like it is on ice.

Orr89RocZ

iTrader: (20)

With power comes great responsibility

xpndbl3

iTrader: (5)

I don'tunderstand.

My car does this.

t-top89

iTrader: (3)

Pm me if you want help. I think your close and my **** hooks pretty good.

QwkTrip

iTrader: (22)

Thanks. You might hear from me later this summer.

QwkTrip

iTrader: (22)

I finally got off my rear and started looking at the setup under the car.

A) Passenger side rear lower control arm is at 0 degree angle, and the driver side lower control arm is at 2 degrees, sloping down toward the axle. It seems an appropriate next step to drop to the next lower hole and see what happens.

B) I measured the rear axle pinion angle and found it to be at +3 degrees. My results were,

Driveshaft angle: 0 degrees
Pinion angle: +3 degrees (sloping upward toward front of car, as measured on the torque arm pad)

Shouldn't the pinion angle be at -2 degrees relative to driveshaft? Or do I need to take into account the angle of the transmission yoke too? I have never dealt with pinion and driveshaft angles so not quite sure what I'm aiming for. I at least do know that pinion angle does have effect on traction, does it not?

This is a manual trans car.

t-top89

iTrader: (3)

For best traction, shoot for -3 degrees off the diff. The rear control arms need to be in the lowest hole.

QwkTrip

iTrader: (22)

Thank you, thank you.

Is the torque arm pad considered parallel with the pinion or is it a better idea to take pinion measurement off the face of the yoke with driveshaft removed? (I guess I could call Strange Engineering and get it straight from their mouth)

QwkTrip

iTrader: (22)

Wait, let's back up a minute....

Does pinion angle even have much effect on traction with a torque arm suspension? Granted, I have zero experience with this but it seems that pinion angle is all about joint wear and nothing else.

Normally for a street car you would want equal operating angles (transmission and pinion) to manage vibration. What benefit am I really getting by moving away from that philosophy? I have a chassis mounted torque arm with solid joints so wouldn't that very much limit climbing of the pinion? Correct me if I'm wrong, but it seems like I should just set up good operating angles and call it a day.

mw66nova

iTrader: (13)

pinion angle does almost nothing. we set it to -2* because it's what we've always done, but i've never seen it actually affect anything. torque arm length and height is a critical part of the IC equation though, as is lca angle. we've had best luck with lca angle going about 2-3* upward from rear axle to body mount. this may be in the lowest hole if your car is super low, but it also may be the middle hole. hole position is also dependent on lca relocation bracket manufacturer, as not all are created equal. lca angle is what controls anti-squat. too much angle means too much antisquat. too much antisquat typically is tough to control with typical shelf type shocks. so....2-3* lca angle is all you need. this will keep the fender gap about level during launch, which is what you really want.

why are your rear lca's different angles?! that's weird.....is the car crooked?

i've been 1.33 60' so far with manual trans. my experience with this so far is that whatever you know about tuning suspension with an automatic is almost completely irrelevant for a clutch car. it's been a lot of work coming up with the information i just gave you above. tons of seat time, tons of testing. i'll help where i'm able. wish we were closer and we could go test it together.

skinny z

That is correct. Crankshaft centre line and pinion centre line should be the same for the reasons you describe.
Work on the LCA angles.

MoJoe

iTrader: (5)

No, and I agree. I think the -2* / -x* / down angle at the pinion was to account for leaf spring wrap during launch at the drag strip... Which does not apply with torque arm.

AlkyIROC

Pinion angle is only to reduce driveline vibration. It all depends on how much the diff rotates upwards under hard acceleration. The angle itself has nothing to do with the driveshaft. The angle of the crankshaft centerline is the angle the pinion needs to be set at. You can angle the pinion down 1-2* from there. Depending on the crankshaft centerline angle, a 2* down angle of the pinion may still look like it's pointed upwards.

Granny

Chances are, it's the clutch that's knocking your tires loose. Ideally, the clutch's holding power should be matched to the power you make with very little reserve. Let's assume as an example that the engine makes 500ft/lbs and the clutch's capacity is 700 ft/lbs before it begins to slip. When the car is launched, that clutch is going to draw 700ft/lbs…the 500ft/lbs that the engine is making at wot plus another 200 ft/lbs of stored inertia energy that will cause the rotating assy to lose rpm. That extra 200 ft/lbs makes the launch more violent, but as soon engine rpm is drawn down to the point that engine rpm sync's up with vehicle speed, rpm ceases to drop and that transfer of an additional 200 ft/lbs of inertia energy stops. The downside is that after you have lost the rpm and used that inertia energy, that spent energy then has to be paid back in full before the engine can recover the rpm that it lost. That inertia energy transfer which made the car launch harder initially now slows the car, as it reverses and some of the engine's power must be used to recharge spent inertia energy back into the rotating assy. In the end, that temporary 200 ft/lb boost did not actually net you any performance gain.

Why subject your transmission and drivetrain to that extra 200 ft/lbs if it doesn't net you anything?
What if that extra 200 ft/lbs of holding power gets you a broken transmission?
What if traction is marginal and that 200 ft/lb spike breaks the tires loose?

If you want to stick a manual trans car on the street, do everything you can to smooth out power delivery to minimize the chances of knocking the tires loose. The number 1 thing you need to do before doing anything to the chassis is to match the clutch's capacity to your engine's power. If you don't do this first, all your chassis tuning will be focused on controlling that huge torque spike that occurs when the clutch is first dumped. No matter how hard that torque spike makes your car launch, it does not make your car any quicker. That spike only lasts about 3 tenths of a second, so why tiptoe around it? Why optimize your chassis for that first 3 tenths of a second when you could be optimizing for the entire duration of 1st gear?

If a clutch with only 600 ft/lbs of capacity were used, it would slip roughly twice as long as the 700 ft/lb clutch, which means the car would be traveling faster at the point where rpm and vehicle speed finally sync up...less bog. Not only does the transmission see less abuse, but the engine doesn't lose as many rpm after launch and after the shifts...the engine will be pulling from a higher average rpm where it makes more power over a given time period.

If your clutch has more capacity than the engine needs, the easiest way to reduce capacity is to reduce clamp pressure. You could simply choose a pressure plate with a weaker pressure rating. Some choose to shim their pressure plate away from the flywheel so that the spring has less pre-load. I choose to temporarily hold back some clamp pressure at the throwout bearing, as it's something that is easily externally adjustable without going inside the bellhousing.

Beyond the clutch, it's pretty important to get as much weight as you can onto the back tires during launch. If the front tires have any weight on them at all, you are not maximizing your rwd traction potential.

skinny z

Most definitely pointing upwards in a more or less OEM configuration. The engines in these cars (and most production vehicles) have a crank centre line that's up at the front about 4 degrees. We measured this regularly back at the chassis shop using a digital level. The pinion would then be pointing upwards about the same amount. Keep in mind, that as long as the angles are equal, 4 degrees up at the crank can be matched with 4 degrees down at the pinion although this is seldom seen. As its been pointed out, this is all about driveline function, not traction.

mrestrictrplate

iTrader: (2)

I used drag radials on all my cars. Sometimes they spin alot on the street. One set I bought new was built 2 years before I bought them so i'm guessing they weren't as sticky as they should have been. Sand on the street doesn't help, plus when drag radials are hot they pick up every pebble sand etc on the road which embeds in the tire. Miles ahead of every street radial practically. They do wear out fast though. Very helpful to win on the street instead of spinning and losing though.

cosmick

Because that theory doesn't work on the street. If you're on 33x21.50-15 drag slicks, it might. Apply it on the street, with an OD trans, and even 315/35R17 drag radials, it might have you running 5.13:1 gears, which is going to render first and second gears useless with any trans.
Here's the correct theory:
For any given car, suspension setup, and tire, there's an amount of torque it can put to the ground without breaking traction. The idea is to make the torque with the engine, then gear it tall so you stay near that amount of RWTQ through as many MPH as possible.
Ideally, you'd do it with an auto primarily to reduce the loss of traction on the upshift.
Most engines won't rev high enough so that they're at the same driveshaft after the upshift as they were before it, but that would be best.
If you were running a TH400 or 4L80E, and boost, and had it at the limit of traction in first gear with no boost, then theory says you'd want 1.7 bar in second gear to stay at the limits of traction. Your acceleration will be diminishing because of aero drag, going twice as fast takes more than 4 times the power, but instead of just being at the limit of traction to 60 MPH, you're now at the limit of traction all the way to 100 MPH.
That post would have us going through the HP peak as many times as possible during an acceleration run up to top speed. The theory is higher average HP. But since you can't hook it up in the lower gears, it doesn't work.
You can accelerate only as hard as you have traction for. Maintaining that acceleration beyond just 25 MPH will races against that higher-average-HP theory.

QwkTrip

iTrader: (22)

You know, I just came to the realization that I'm chasing the wrong problem. Nearly everything I don't like about my car pretty much comes down to compromises made to keep that damn UMI torque arm from smashing into the ground. Super stiff springs, the punishing ride, lack of traction, high ride height, almost no ground clearance --- None of this is what I wanted. Heck, I even have the correct springs in my garage but don't dare run them or the car will sled on the ground.


All I have to do is rip out that UMI torque arm and I can solve most everything in one shot.



I need help interpreting this. At first I thought you were saying set to -3 degree operating angle, which seemed arbitrary. But I am now thinking you mean to set operating angles equal on both sides of driveshaft (whatever that number is) and then offset the pinion by -3 degrees?



Yes, I really value your experience. Especially appreciate those LCA angles. Thanks.

redneckjoe

although our cars arent 4-links, you may find some useful information in this link about instant center, anti-squat, etc?
http://www.how-to-build-hotrods.com/tuning-4-link.html