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Discussion Starter · #1 ·
well i finally got my RHP 521 SCJ-A motor to the track to do some shakedown passes. of course since everything is new so i have to learn the car all over again. not to mention a new bronze faced metal to metal clutch.

https://www.facebook.com/?ref=hp#!/...ffset=0&total_comments=24&notif_t=video_reply


on my first pass, i hit the throttle hard for only 2 out of 4 gears and then cruised down the track to get a feel. i am only launching at 3500rpms which is measely what i'm use to the 460 when i launched at 4000-4600rpms.

i then let motor cool down and did another pass with no changes other than 15psi in the tires and i did a 11.4000 pass at 124mph and shifting at 6100rpms. i know the launch is measly cuz it was only a 1.78 60 ft and my old 460 would launch a 1.67 to 1.73 60 ft launching at 4400rpms.

i let motor cool and did a 4000 rpm launch. my clutch for some reason isn't quite fullying disengaging. in the air, the tires will spin slowly when clutch put in. i called moderndriveline and they said its normal for a brand new clutch becaue i can easily stop the tire from moving when its moving. when the car is on the ground, it won't move the car. at a 3500 two step rev and clutch in, car doesn't move. well with a 4000rpm launch, car starts creeping forward. so i starting rolling thru the traps right after the first yellow light came on and my time started. i had a -.550 reaction time of course the rolling start showed on the time slip. i clocked at 11.4990 at 123.8mph.

on the next pass my friend who did my ladder bar suspension called me and told me to try 12psi in the tires. this time i will try to stop the car from rolling by applying the line lock to hold the car. when i did my burn out the car is NOT liking a 1K idle so didn't want to get embarrassed and have the car stall so i tried to lightly hit the brake and hit the gas while activating the line lock. well i two stepped it and i start to roll again and i am staring at a red light and i just take off anyways. that car launched harder than i ever felt it before. the 460 could slightly pull the tires off the ground and i felt i was a little higher this time. i could feel the ladder bar suspension digging those small 10 inch tires i have into the ground. after my first shift though, i started side shimying. the back end felt loose and wanted to sway so i pulled a measly 12.0001 because i was steering and got out of it.

the ladder bar suspension really doesn't like to be "pussy footed" on the launch and i can tell and it wants to be hit super hard. now i'm at the point where i run 14psi and not get swirly but not get good launch or run 12psi get swirly but get a monster launch. i run MT's with no tubes and screws and i'm leaning towards really needing tubes to keep my sidewalls stable.

the 3055s is what i have and requires the smaller tubes and i want to use a cheater 3055w tire next but requires the bigger tubes. i'm at the point where i should just sell my 3055s to somebody who wants to try slicks and i only got about 70 passes on these with light burnouts on them and i know people get close to or more than 200 passes on moder hp cars. so i am thinking about mounting the 28x10.5w - 15s on my 10 wheels even i know those are the min size they need with tubes and screws. people love the W tires cuz they are a softer and better compound. i think the tubes will benefit me alot.

now to what i need to get down to. when i cross the line at 124mph i remember seeing the rpm somewhere between the 5500rpm range to maybe 5700rpm and definitely not a 6000rpms. on wallace racing calc, it says i should of been at 5500rpms. my max HP is at 5300rpms and then the power maxes out again at 6000rpm (the 6000rpm mark actually makes one half more hp), so considering that i should probably shift at 6200-6400rpms. i only shifted at 6100rpms since it was just a TNT and shakedown passes. i know i should be crossing the line at LEAST 6000rpms but probably preferably the 6400rpm range. i set the rev limiter to 6500rpms. to do that i'll have to be in the range of 4.0 to 4.11 gear. going to a 3.89 would be minimal since i got 3.70 now.

on wallace calc, it says if i went with a 4.11 gear, if i crossed the line at 6500rpms i can reach 132.21mph which would be great. but there is also the claim people says on a stickshift car, low gears on a big block stroker is useless. but what if i got the suspension and tires to carry it? i mostly dont use first gear on the street and it'll actually make my OD more useful.

a 4.11 gear would maximize my motor passes and leave no room for improvements when i shoot the nitrous. if i left the gears in there, i'll just be bouncing off of the rev limiter sooner. thats where the 3.89 and 4.0 gears looks better. should i consider having two 3rd members? they are small and the wife won't know i got a extra one. :D i also got to consider when changing gears that i picked up 6mph when i changed from 3.50 to 3.70 gears on the 466 motor. so my 124 can easily grows with a gear change.

all in all, the motor is running strong and i just got to get a handle on the timing with another dizzy and RHP is helping me out already. thinking more along the lines of 14 initial timing and 28 total timing and hooking up manifold vacuum to dizzy. i need to run tubes since running lower pressures launches better but i get swirly and going ahead and going to a larger tire. and figuring out a good overall gear for the motor passes and nitrous. the nitrous won't come for quite sometime so i just need help really deciding on the motor passes. i have alot to think about.

i have ford vs chevy night in two weeks. til then, i have to figure out the clutch disengagement issue, tubes issue and the dizzy. the dizzy by RHP is already in the works. tomorrow i'll start with the clutch issues and start ordering tubes.
 

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Nice writeup!

I take it that you are running a close ratio top loader? Or? As you note that you don't use 1st gear on the street. If so,i would think that you would be better off using a wide ratio instead.

At least that is what i intend with my 67'

From your description, it sounds as if the 3055w's are over matched if not slightly. Tubes and screws are required i think, on anything that has a seriously hard launch.

Any sign of tire slip on the rims?
 

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Discussion Starter · #3 ·
Nice writeup!

I take it that you are running a close ratio top loader? Or? As you note that you don't use 1st gear on the street. If so,i would think that you would be better off using a wide ratio instead.

At least that is what i intend with my 67'

From your description, it sounds as if the 3055w's are over matched if not slightly. Tubes and screws are required i think, on anything that has a seriously hard launch.

Any sign of tire slip on the rims?
nah, i am running a tremec tko600 which is holding up to my abuse. it has the upgrades for shifting higher and other little mods to hold up to a lil more power. i wish the tremec was able to change gears like a jericho or doug nash but it ain't other than being able to change the 5th OD only.

i run the 3055s now but i think i need the 3055w for the extra meat on the ground and more section with with only the expense of 2 lbs each tire. i need tubes regardless now i think and i already run 8 screws per side. no sign of slippage since i screwed tires down.
 

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Ah.

I think that the Doug Nash transmission would be a good choice as its gearing allows high gear sets in the differential. Like 2:79:1 or 3:00:1's or at least that's the way they where geared.

Anyway, i tend to just think street fun, not really racing..
 

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Discussion Starter · #5 ·
Ah.

I think that the Doug Nash transmission would be a good choice as its gearing allows high gear sets in the differential. Like 2:79:1 or 3:00:1's or at least that's the way they where geared.

Anyway, i tend to just think street fun, not really racing..
my trans is geared alot like a T5 and i seem to have the suspension to hold the steep 2.87 first gear and 3.70. i need to out if a 4.11 is going to be a good gear to run with my combo or is it going to be better to run a 3.89 or the hard to find 4.0 gear.
 

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You running the 8th now right?

I ran a 4:62 rear and close ratio with my old set up, trap RPMs in qtr were 7200 on 27 inch tires.

My current set up is 4:63 and wide ratio 2:93 first gear, but going with Jerico - 28 inchers, soft lock clutch.

Many folks say this is too much, but I keep reading and researching different combos, one I like the most is a 68 fast back, FE big block, runs Jerico with a 3:00 first gear and 5:13, clocks corrected high 8s in qtr. Runs strong. Not sure what his trap RPM is though. Im gonna start with the current gear, and work back for 8th mile.
 

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Discussion Starter · #7 ·
You running the 8th now right?

I ran a 4:62 rear and close ratio with my old set up, trap RPMs in qtr were 7200 on 27 inch tires.

My current set up is 4:63 and wide ratio 2:93 first gear, but going with Jerico - 28 inchers, soft lock clutch.

Many folks say this is too much, but I keep reading and researching different combos, one I like the most is a 68 fast back, FE big block, runs Jerico with a 3:00 first gear and 5:13, clocks corrected high 8s in qtr. Runs strong. Not sure what his trap RPM is though. Im gonna start with the current gear, and work back for 8th mile.
No, I run 1/4 mile. It looks like if I gain about 3mph with a gear change that with a 4.11 I could trap at 6200rpm at 127mph. My Max HP is at 6000.
 

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I think the 385 based builds, are usually a low to mid 6K RPM motors, guy I am refering too makes 865 at 7000 with an FE, and his is hi comp and stout.

4:60s would be way to steep for you in qtr, maybe for me in the 8th. I am figuring 6500 to 6800 for HP TQ range.

Good stuff though, nice write up. Interesting comments on ladder bars, the articles I read are all ladder bar cars, while I am running narrowed and tubbed, CALTRACs. Totally different concepts for getting them to hook. One car squats, while the other one goes up, extends shocks.

That first pass has to be something, did you do the frame work your self? I am going to abuse mine for a few 60 ft hops, be sure all my welding holds up
 

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Discussion Starter · #9 ·
I think the 385 based builds, are usually a low to mid 6K RPM motors, guy I am refering too makes 865 at 7000 with an FE, and his is hi comp and stout.

4:60s would be way to steep for you in qtr, maybe for me in the 8th. I am figuring 6500 to 6800 for HP TQ range.

Good stuff though, nice write up. Interesting comments on ladder bars, the articles I read are all ladder bar cars, while I am running narrowed and tubbed, CALTRACs. Totally different concepts for getting them to hook. One car squats, while the other one goes up, extends shocks.

That first pass has to be something, did you do the frame work your self? I am going to abuse mine for a few 60 ft hops, be sure all my welding holds up
my ladder bar was installed by a fellow racer who runs a business too. looks pretty legit and all the welds was triple passed on everything.
 

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Discussion Starter · #10 ·
i improved the ET at a ford vs chevy race. i improved .215 in even worse conditions. it was 107 degrees. Scotty J recurved my dizzy so i could have 15initial timing and 28 total and it made the world of difference trying to stage the car.

i improved to 11.185 and some of its due to using tubes in the slicks now and launching a little harder.
 

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Getting better.....don't know that I would mess with the gears at this point. Get everything working right then see what you have. That 521 doesn't need alot of gear to move the car....you don't want to mess up the launch. A little bit goes a long way.....D
 

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Discussion Starter · #14 ·
Getting better.....don't know that I would mess with the gears at this point. Get everything working right then see what you have. That 521 doesn't need alot of gear to move the car....you don't want to mess up the launch. A little bit goes a long way.....D
so you suggest not moving up from 3.7? i'll work on a few other things like losing some weight on the steel hood and heavy bumper.
 

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tires

I wanna chime in a little, if you stay with the s side walls when you change over to 4.11 gear you will have enough tire growth to get to the stripe @ 5800 to 6000 RPM if you change over to the W's you will not have the same tire growth because of the stiff side walls so your finish linr RPM will be around 6100 to 6200 RPM, so I think you will be ok with the 4.11 gears and the s's, good luck and happy racing!!! :D
 

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The 4.11's look good on paper, and are by no means a wrong or bad choice. I do not know your engine combination......sounds like you are getting your suspension sorted out and may easily handle the increase in gearing, I would just be afraid of hurting your 60'. Don't let my babblings stop you from experimenting. May very well go quicker and you will not know unless you try it with your combo. Does sound like you need to be crossing the stripe at upwards of 6500. So you could even try 4.30's or 4.44's with the tire growth if ya wanted to.....D
 

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Discussion Starter · #17 ·
I wanna chime in a little, if you stay with the s side walls when you change over to 4.11 gear you will have enough tire growth to get to the stripe @ 5800 to 6000 RPM if you change over to the W's you will not have the same tire growth because of the stiff side walls so your finish linr RPM will be around 6100 to 6200 RPM, so I think you will be ok with the 4.11 gears and the s's, good luck and happy racing!!! :D
i already went with the W's with a tube.
 

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Discussion Starter · #18 ·
The 4.11's look good on paper, and are by no means a wrong or bad choice. I do not know your engine combination......sounds like you are getting your suspension sorted out and may easily handle the increase in gearing, I would just be afraid of hurting your 60'. Don't let my babblings stop you from experimenting. May very well go quicker and you will not know unless you try it with your combo. Does sound like you need to be crossing the stripe at upwards of 6500. So you could even try 4.30's or 4.44's with the tire growth if ya wanted to.....D
my max power is at 6000rpms where i made 626 hp. weird thing is, i made 626 at 5300rpms and at 6000rpms. my torker II intake is definitely causing some bottlenecking of some sort.

a 4.0 gear would be perfect but nobody seems to really carry it. i should cross the line at 6000rpms and its either .11 lower than 4.0 or .11 higher. i don't think a 3.89 will be worth it from a 3.70 for a gear swap.
 

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How tall a tire/slick you running. 4:10 with a taller tire, or Vice Versa, get on the computer and play with tire gear combos to get the RPM you want, using your current set up as baseline.
 

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Discussion Starter · #20 ·
How tall a tire/slick you running. 4:10 with a taller tire, or Vice Versa, get on the computer and play with tire gear combos to get the RPM you want, using your current set up as baseline.
i am using a 28 inch tall tire. i'd like to cross the line at 6000rpms but i hope my tires and ladder bar suspension can hold up to a 2.87 first gear and a 4.11 gear.
 
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