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PostPosted: July 10, 2016, 3:02 pm 
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Ford did the same sort of thing a number of years back when they tried to market a Zetec crate motor to the midget car drivers in Circle track. The Zetec was an attractive package but Ford priced a relatively unknown engine well above the price of a fully sorted "Whatever-the-hot-set-up-was-at-the-time" engine.

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PostPosted: July 10, 2016, 5:16 pm 
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That's still true of every single one of GM's crate engines.


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PostPosted: July 10, 2016, 5:24 pm 
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horizenjob wrote:
I think if you get these motors on a scale ( and their transmissions ) you're going to find they are quite heavy. Much worse though they are very bulky, tall and so very complicated. I think what do is make better mileage possible by being able to run at slow speeds and lower power without the issues of a large displacement engine at high intake manifold vacuum.

These engines have 4 cylinders, but they are nothing like the old 4's in these cars from years ago in terms of size or weight. If anyone wants to get out a tape measure, I think my Ford 302 is smaller than these engines and not much different in weight - maybe lighter with the T5....

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To me the transmission is the car. It's what you have contact with the most and what gives you grief if the ratios or effort is wrong.


There is a lot of truth in what Carguy is saying here. The thing I remember most about driving my formula ford is how much fun it was to shift and how when you were getting it right you really felt you were with the program so to speak. Why is it so hard to get these parts for car transmissions? :BH: Every motorcycle has a dog clutch transmission.

On my FF after the first year I never used the clutch, just the quickest lift possible - you apply pressure to the shifter, the lift happens and it just jumps to the next gear. You can feel the weight come off one tooth and feel the next tooth grab hold. They sell some of these parts for T5's but I think they are set up for drag racing and might not stay in gear in normal use...

My experience with dog clutch transmissions is very minimal, but I prefer a stock WC T5 with a Steeda TriAx shifter, nothing ever gave a better feeling shift. And if you baby a T5, they'll take 500 horses, but then they're no fun to drive if you are being gentle enough.


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PostPosted: July 10, 2016, 5:33 pm 
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[quote] To me the transmission is the car. It's what you have contact with the most and what gives you grief if the ratios or effort is wrong.

Probably a whole nuther great thread. I've read build logs for people who tell me that the first couple of gears on their build are totally useless, which makes me wonder why they didn't change the rear end ratio or the trans ratios?

Ability to shred tires through the first couple years is fun, but for best acceleration with any given tires on any given car, the idea is to have a parking lot ratio, then more importantly have a taller first acceleration gear that lets you keep the torque at the limit of what the tires can hold to as high a road speed as possible. Suppose you have a 4:1 axle and the tires will hook 3600 foot-pounds. Then you use a 3:1 first with an engine making 300 ft-lbs. Then if second is 2:1, about 7 psi of boost from a turbo should result in around 450 ft-lbs to the trans, keeping it at 3600 to the treads. This is the idea behind multi-stage nitrous kits, too.


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PostPosted: July 10, 2016, 6:51 pm 
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Dave1976 wrote:
My experience with dog clutch transmissions is very minimal, but I prefer a stock WC T5 with a Steeda TriAx shifter, nothing ever gave a better feeling shift. And if you baby a T5, they'll take 500 horses, but then they're no fun to drive if you are being gentle enough.


Bookmarking that shifter for later use. Thank you.

And I have to wonder if the 500 horses (presumably 500 ft/lbs?) is the same when you have a 1400 pound car as when you have a Mustang or Camaro? Either the wheels break loose, or the engine finds it tough to stay at peak torque for as long when the car's mass is a lot less?

Disclaimer -- liberal arts degree, not an engineer, etc....

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PostPosted: July 10, 2016, 7:47 pm 
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In my mind, if you half the load, you double how much power it can take. GM's 7.5" axle is marginal at 500 horses in a street Camaro, but the Bonneville guys put 1500 horses through them out on the salt flats. But powershifting hurts T5s, so I still wish for a TKO600.


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PostPosted: July 10, 2016, 8:16 pm 
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Dave1976 wrote:
But powershifting hurts T5s, so I still wish for a TKO600.


I recall a web page where they strengthen the shift stops or something, which supposedly addresses some of the issues? I recall that the GM people put in a restriction in the hydraulic clutch hose that supposedly prevented clutch engagement shock to some extent?

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PostPosted: July 10, 2016, 9:33 pm 
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Most of the aftermarket shifters for T5s have stops, and those are a good addition, but re-engaging the clutch abruptly at full power is a separate problem. If you want a T5, get the Astro Performance case, it goes for around $300, and use it with the Ford-spec 2.95:1 gearset.


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PostPosted: July 11, 2016, 12:17 am 
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In my mind, if you half the load, you double how much power it can take. GM's 7.5" axle is marginal at 500 horses in a street Camaro, but the Bonneville guys put 1500 horses through them out on the salt flats. But powershifting hurts T5s, so I still wish for a TKO600.


These cars are potentially a lot lighter than Camaro, Mustangs etc.. So I'm hoping a T5 works fine. Most of these cars have well under 800 lbs. total on the rear wheels, so they won't take a lot of torque. They'll swap ends quickly too, a rough shift to third on one of these cars with real power is maybe a fatal accident. You used to be able to see this happen on Indy cars when they did starts or restarts, for them it was just the turbo spooling up.

ALl these things are hard to compare because I'm not sure they are well specified. The people who make them know these answer but there isn't much need to publish torque ratings for cars that weigh one quarter the normal car or go four times the speed of a normal car. So 500 HP in a Camaro and 1500 Hp in a Bonneville car are probably the same amount of torque. It's just turning faster in the Bonneville car.

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PostPosted: July 11, 2016, 5:23 am 
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I've always felt that a high power/weight ratio, rather than tons of horsepower, should be the desired goal in a 7. I'm aiming for 1200 lbs. all-in for weight, with about 185 hp., giving roughly 6.5 lbs./hp.

To get that ratio in, say, a Camaro, you'd need over 600 hp. Their 2015 6.2 liter V-8 version has only 426 hp., weighs 3908 lbs., giving a ratio of 9.2 lbs./hp. - almost 50% more lbs./hp. than my Locost. Of course, there's always the almost-2-tons of weight to have to hurl around turns, too.

I figure that my 185 hp. will be "sufficient". My buddy (who's building the "sister ship" to my car) wanted to put nitrous on his. I suggested he wait until after seeing what the cars are like on the road first. IMHO, shredding tires, while fun, is not the fastest way around a road course and, without a tire sponsor, rather expensive into the bargain.

Back in the '70's, I used to race my 1965 Austin Cooper Mk. 1 in rallies, autocross, slaloms, etc., and it was almost unbeatable. It only had, probably, about 70 hp., but it was light and agile. The only car that ever beat me consistently in slaloms was...a Super 7. 'Course, it beat everything else that came out to compete, as well. Small wonder why I always wanted one...

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PostPosted: July 11, 2016, 9:16 am 
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Don't need much rear weight to hook big power, I know my S-10's rear weight is right at 1000#, and with just CalTracs bars and drag radials guys are hooking turbo LSx swaps.
I forgot to note earlier that the T56 Camaros did use a restrictor in the clutch release hose, not sure why, but the real world result was that when powershifting up through the first 4 gears, like at a quarter mile dragstrip, missing the 3-4 was common until someone discovered the restrictor and tried drilling it. Now everyone drills it.
Bonneville offers no traction, so full throttle in the lower gears just spins the tires.
Having tried less than 5 pounds per horsepower, I strongly advocate never going past that point in any car, it makes a far quicker-accelerating ride than there's any benefit from, it is challenging to keep under control, and taking your breath away doesn't begin to describe it. Soiling your boxers might.
The way I over-build, my LoCost is likely to end up at 2000# with fuel and no people, I weigh 230-ish, and my goal is 450 controllable horses. I've won many races against more powerful cars mostly by being able to take full advantage of all I do have, and I'd rather back down to 400 than shred drag radials. They aren't cheap, they don't last long anyway, and it will accelerate harder just before breaking traction. But really, I will try a taller axle ratio before trying less boost. Not only reduces torque to the ground, but helps the turbo have more load to spool against.


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PostPosted: July 11, 2016, 12:04 pm 
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Dave1976 wrote:
Having tried less than 5 pounds per horsepower, I strongly advocate never going past that point in any car, it makes a far quicker-accelerating ride than there's any benefit from, it is challenging to keep under control, and taking your breath away doesn't begin to describe it. Soiling your boxers might.


As a comparison, an IndyCar is probably somewhere near 2 pounds per HP in road/street trim under Push to Pass. I figure that F1 is in that ballpark too. IndyCar claims 5500 - 7,000 lbs of down force at 200 mph, which of course, changes everything. The word is that this is more down force than F1 makes.

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PostPosted: July 11, 2016, 12:52 pm 
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Don't need much rear weight to hook big power, I know my S-10's rear weight is right at 1000#, and with just CalTracs bars and drag radials guys are hooking turbo LSx swaps.


As Homer Simpson says, "here in out forum we follow the laws of physics". You're right, but there is a whole combination of things going on here. Drag slicks are especially good at putting down power, they have a very high coefficient of friction - depending on how much money you spend maybe a lot more. With that and the fact that an S10 is a pretty tall vehicle they can shift most or all of their weight onto the rear tires. So they aren't doing that with 1000 lbs.

The formula ford in my avatar is an entry level race car. Mine had 106 HP and even with sticky slicks it can burn rubber, or at least it will spin the tires ( not much burning because of not much weight on them ). It's about 200 lbs. lighter than a locost but has a bit more rear weight distribution.

It will do this even though it is geared for about 70 MPH in 1st gear. It then shifts at 85 and 100 MPH. That's for a slow track. On a fast track I put in a taller 4th and move the other gears down one and take out the 1st.

I think what that means is that a light car like ours wants close and high ratios. It's not hard to get it moving since it doesn't weigh much. It does't seem to me that you can actually change the ratios much on car transmissions, but I am ignorant on this. For instance I don't think you can just swap the gears around like on my race car ( 3rd to 2nd etc. ).

What would be good for us is something like a close ratio motorcycle transmission that could handle our torque...

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PostPosted: July 11, 2016, 4:36 pm 
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For choice of swappable ratios, the Richmond gearboxes are all there is in the longitudinal style. But if you want to build a muddy around fwd car stuff, there are a few good choices of transaxles with too-close ratios and strong enough to hold 300 horses in a 3000# car, but the cruise rpm would be way too high, with final drive ratios around 5:1, which even in sixth gear is still around 4:1, while first gear is somewhere in the mid 2s. Better to go wide-ratio with an engine that makes torque in excess at every rpm.


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