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A new bullet
https://slantsix.org/forum/viewtopic.php?t=28649		 Page 15 of 20
Author:  Exner Geek [ Thu Mar 04, 2010 8:11 am ]
Post subject: 
TRW pistons have always had those holes in the center, probably to locate them for machining. They are quite deep but as far as I know have never caused a problem. One thing you do not want to do is machine the inside of the head of the piston to save weight, a friend did that and it burned through quickly in a normally aspirated engine.
Author:  nwstal [ Tue Mar 09, 2010 10:20 am ]
Post subject: 
Your car is sweet... Have you considered running taller tires instead of changing gear ratios, There is a formula to figure out top speed with different gear and tire sizes I can't remember it offhand but the taller the gear the harder it is on components if traction permits that is. Lower gears and bigger tires tend to hook up better than taller gears, because they arent trying to spin the tires so fast. Just a thought.
Author:  Joshie225 [ Tue Mar 09, 2010 12:00 pm ]
Post subject: 
Quote:
Lower gears and bigger tires tend to hook up better than taller gears, because they arent trying to spin the tires so fast. Just a thought.
Larger diameter tires have a longer contact patch, especially slicks. This is the #1 reason for tall tires. If the gearing is changed to accommodate taller tires then the torque applied at the contact patch stays the same.
Author:  nwstal [ Tue Mar 09, 2010 3:31 pm ]
Post subject: 
I was more referring to top speed changes by using taller tires therefore more traction. For instance Redline 5200 RPMs Final Drive 1:1 being constant...
for 130MPH Top speed (11404 Feet/Minute)
3.08 Gears Tire RPM = 1688 26" tire
2.76 Gears Tire RPM = 1884 23" tire

150 MPH (13200 feet/minute)
3.08 = 30" tire
2.76 = 27" tire

The idea in a 1/4 mile car being to hit your rev limit at the traps otherwise your either wasting good power by not or hitting your rev limit sooner and not going as fast as you could be. Traction permitting of course which reducing your tire speed will help. Thats why most run 5.11's with 33's when they can rev to 7200 (top speed 138Mph). Low tire speed off the launch helps keep the tires connected to the pavement and bigger tires make up the speed difference. All of this is purely numbers but for the most part numbers don't lie. :)
Author:  Joshie225 [ Tue Mar 09, 2010 3:42 pm ]
Post subject: 
Larger tires are needed to transfer greater torque to the road surface. Larger tires are able to transmit more torque due to rubber's non-linear coefficient of friction. To offset the longer moment-arm of the larger radius tire a numerically higher gear is needed. The tire's lower rotational speed is a byproduct of putting more rubber on the road by increasing the tire diameter to lengthen the tire contact patch.

I know what you're trying to explain, but what you're explaining does not speak toward the fundamentals at work.
Author:  turbo66valiant [ Tue Mar 09, 2010 5:39 pm ]
Post subject: 
Say, I would run a taller tire but space is limited and 5 on 4" bolt pattern limits rim size. Plus, I like to spank the BB Chevys using 5.11's w/ 33's.

Thanks Seymore for resolving my TRW piston question.
Later
Author:  nwstal [ Wed Mar 10, 2010 11:04 am ]
Post subject: 
Your car seems to be a drag car so doing the math might help, space is always the problem... I liked beating low geared cars, Taller gears would seem to be a faster combination. I got into an argument with one of those chevy guys about how limiting their top speed with gears seemed to be a faulty train of thought. I ran 2.76s in my street car, it would hit 13's all day long ending a 1/4 mile midway through second gear. To me if you limit your speed by running low gears it would seem that you aren't getting all that you can. Physics wise matched gears and tires make sense, but in real world If your car can hit 200mph you just need to add more power/traction to be able to be there in a shorter distance. Plus I like freeways and its way too fun stomping honda's on "their turf" rather than on ours.

Mr. Skinner... Engine speed and Axle speed are constants with any gear therefore big tires spin the same speed as little ones its only the distance they cover per revolution that changes. If you change both tire and gear ratio you end up with the same thing you had in the beggining.

Sorry for starting an argument it was just a thought.
Author:  Shaker223 [ Wed Mar 10, 2010 11:56 am ]
Post subject: 
More gear won't help here as the engine is RPM limited. Shift points for this car are 5200 rpm.

This engine makes a butt load of power down low and runs out of steam up top (like mine). More gear and it will run out of engine before the end of the qtr.
Author:  USAJon [ Wed Mar 10, 2010 11:25 pm ]
Post subject: 
back in th day we ran cool cans..they still legal?
Author:  turbo66valiant [ Fri Mar 12, 2010 5:34 pm ]
Post subject: 
Yes they are.
Later
Ryan
Author:  turbo66valiant [ Sun May 02, 2010 7:56 pm ]
Post subject: 
I went and got motivated today.

Here is a pic of the center two intake runners of the stock Clifford HyperPak. The ports are decent but they neck down at the outlet! All the others were the same. BIG ramp on the floor of the port!
Image

This is the intake afterwards.
Image

Here is the 10.90 head. I may work alittle on this also.
Image

And the intercooler is installed completely and started working on the hoses.
Image

Later.
Ryan
Author:  Shaker223 [ Sun May 02, 2010 8:46 pm ]
Post subject: 
Intakes normally have some taper in them for naturally asperated applications but as you know, boosted apps are totally different animals. Here is what I found with a stock Offy intake (same as you). The carbon witness marks are the stock ports with no mods and the paper cut out is my ported head.

Cool pic with the Dart in the background.


Image[/url]
Author:  turbo66valiant [ Mon May 03, 2010 7:47 pm ]
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Say Tom, what I/Exhaust gasket are you using and do you have any pics of the head ported? Also hows the cut up intake coming? Still deciding on if I'm building a new header or just modifying my original. Later
Ryan
Author:  Shaker223 [ Tue May 04, 2010 5:20 am ]
Post subject: 
I have the Aussie mega gasket (I think that is the name). It is the large port gasket. Kind of looks like the one you have in the above pics.

The intake is on my shelf waiting to be welded. I need to find the time to take it in to a friends shop one weekend.

I have not taken any pics of the ported head.

Tom
Author:  maxracer21 [ Tue May 04, 2010 6:17 am ]
Post subject:  full throttle
I'm working on your delimma..............Have you got a 390 4bbl you can borrow just to try? It would help my research on your engine considerably. It can be fixed and it's something you are just over-looking . I'd say something very ,very simple.
I know you don't know me but I'm a retired drag racer and this is a challenge for me. been racing these things since 1967.
best regards,
digger dave
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