Trying to get higher in the RPM's
 

Hello all, I am trying to help a friend out with his Mustang. He has a 351W, Windsor heads, 700carb and he has the performer rpm intake and cam combo from summit.
The cam spec are 224/234 dur 496/520 lift. He also has 1.6rr which bumps his lift to about 526/550. He has a 5 speed with 373 gears.
The car is simply a beast and has plent of torque but it he is looking to get a little more top end and faster 1/4 times.
We are not sure if he should look into a cam with more duration or drop down to some 355 gears???
Any help is welcome.:D
rocc

A victor jr. will raise the rpm some. I think a carb spacer does to, but ask or get more replys on that.

Two things I'm not quite understanding:

1) 1.60:1 rockers increase the lift? That would mean that the intended rockers are about 1.51:1? Just making sure here.

2) Also say that you want to drop to 3.55's to get the RPM's higher? That will have the exact opposite effect. Going to 3.55's from 3.73's will drop the rpm about 6.1% at the same MPH. I'd go up to a 4.30 gear or even better yet a 4.56 gear for the carbureted combination.

You don't say where he's making power or shifting things now, but just looking at the cam specs, I'd say that he needs to look at a different cam. What's the lobe CL on the cam? I've been shifting my Weiand Stealth / Holley 650 combination at as much as 7400rpm so his carb and intake should breath that high as well even though he's moving more air than my 306ci motor.

Actaully i got a question this as well.

We all knwo the mod motrs come out as reving monsters.

However i was told a long time ago taht actaully pushrods are more stable for high revving applications. Dont knwo how or what i was told but kinda curious about this as i dont see why.

I was highly considering using a 351 and making a reing machine
peaks at right about 7,200-7,500 RPM. Now i realize thats some crazy RPM but i will have everythign forged and balanced along with better valvatrain components.

The question is since its gonan be reving liekc razy how will my gas mileage be whe im normally crusing aroudn at 2,500?

Im sure gas goes to **** when im at 7k but thats expected.

This combo will be FI by the way.

Also im thinking im gonan run into lots of vacuum problems how do i go abotu curing this or do i jsut gotta lsoe power steering and brakes or can i make somethign electric instead and maybe keep power steering? or vice versa?

Thanks

Thanks alot Jeff, Lets see if I understand this
1- Yes that would increase the lift. Are you telling me that if a cam is intended to use 1.5 than you shouldnt move to a 1.6 or any other size than the intended rr? Thats a new one if you are???

2-OK I was under the impression that steeper gears will give you more torque and your powerband will be lower than if you went to a smaller gear. A smaller gear will not have as much on bottom but will be able to get a little higher in the rpm's.

I am not sure where he is shifting at. He is a member on this board I will try to find him and get him in here.

What are the spec on the cam you are using?
Thanks alot and please let me know if I am in the wrong here at all.

Oh Yeah vetteeter, spell check my friend:D Go with the 351. My buddies car is a beast and it wants more....

What I was getting at was that I don't believe the 351 cam that he's running was designed for 1.5:1 rockers. I could be wrong, but its suspicious to me. Therefore, it might not really be giving the lift that you've calculated. The only real way to know is to do a vavle lift check at the retainer, and even then you'll have some valve train deflection that will decrease the effective lift. If he's not getting the lift that he thinks he's getting, then it might be impacting the rest of his combination. The engine won't make the power or sping the RPMs if he's shorting himself on valve lift; it directly affects the volumetric efficiency.

Gears won't effectively change the powerband. You use gears to get you to the powerband that your engine is delivering. They do however provide torque multiplication. So a 4.10 gear is going to give you better leverage than a 3.55 gear. Lower numerical gears will allow you to run more MPH at a given RPM, while higher numerically gears will allow you to run more RPM at a given MPH.

The specs on my cam are different than his....I'll leave it at that.

OK I thought that duration determines where you make your power at not lift. I understand that lift will get mor air into the engine but that wouldnt effect the rpm's where he makes his power at. So moving up to a 1.7 would help him out??

I am a Chevy guy myself and he is Ford through and through(makes it fun) but we are both in the Army stationed in Germany. We have a Autobahn over here, I dont know how familiar you are with the Autobahn but imagine all the freeways in the states with no speed limits....As fast as you can go.
Well when we line em up and go he always gets me good off the line, but I eventually reel him in and pass him. Its like his cars just has no more when we both know it does. I have 3:23 gears and he has 3:73's. I am not talking racing two miles or nothing but just till we run hit about 130mph.
Thanks, rocc

as far as i know i thought 1.6 ratio was the stock ratio

I am the one my buddy has been trying to help. I am trying to get more out of my engine. We have fun running the cars but I would like to get more top end. I have been reading on cams and it seem like that is the way I need to go so far. Tell me vetteeatr why do you think 1.6 are stock rollers? Jeff if you don't mind me asking is your cam a custom grid inwhich steering me in another direction. I am trying to learn more about this so that I can get the best preformance out of my car.

Well i was pretty sure 5.0 come stock with 1.6. Actaully missed it wasnt a 5.0 lol but still it think the same applies to the 351. Ignore me lol

It sounds to me like what you want is more HP not more RPM's. My cobra makes 320 HP @7000RPM's, My friends stang makes 400 HP @ 5400RPMS. He out pulls me from start to finish.

well actually i kinda wanted more RPM so i could run more of a great handling car with 17s or so which we all know isnt gonan be able to take lots of low power down low. So i wanted to keep power lower in teh lower RPMs so i coudl kinda have a car that could fly but not have so much down low all i i do is spin. Its not gonna be a drag car and ill be runnign like 3.08's or something.

More of a top speed road racer but could still tear some stuff up on the drag strip.

Although if i wanted a drag car yeah i woudl go your route and jstu put some 15's wiht some slicks. and in reality i would probally actaulyl have soem cheap 15 inch rims wiht tires to bring to the strip when i wanted.

Maybe i dont understand all the power ranes but i assumed the farther up i moved the powerband the less traction porblem si woudl have down low.

Well crap i had this whole dissertation written out and lost da^^n computer

Okay once again ALL windsor motors (255,260,289,302 and 351w not clevland) com with 1.6 rockers stock for you to have the lift according to your math you would need to be running a 1.7 rocker. EDE rates that cam with the stock 1.6 rockers.

Now from what I have read i would say go to the 3.55 i am not writing all the formulas and math examples i had before the OOPS but with you motor at the same given RPM you will be faster assuming your motor is stong enough to pull with the lower gears

think of your tranny how fast can you go in 1st gear? 30ish? but how fast does it gain that 30mph now in 4th How long does it take you to accelerate from 0 to 30mph? The reason being that when you car is in first the way the gear ratios work out is with a 3.35 first gear with a 3.55 rear gear would be like being in a 1:1 fourth with a 11.8925 gear. Hence the reason that when you go to numerically taller gear you car accelerates faster but would have a slower Top speed and vice cersa for the numerically lower gears. Now that being said if the motor can't provide the need power to pull the same amount of revs then you may actually slow yourself down as in the case of a bone stock fox body they actually pick up about 5mph by going to 3.55's because they don't have the power to pull the numerically lower gears as fast as the 3.55's it is also the reason why alot of T-56 cars fall on there face when they hit 6th becaus the ford spec is the only T-56 to have a .63 od VS the others with there .5 od the gearing is so low for them they can't pull it.

Not even close vette ... there are overhead cam motors in racing applications that they are turning in the neighborhood of 16,000 RPM Try that with pushrods.
Oh and the 1.5 rocker ratio is small block chevy ! Small block Ford is 1.6

OK I am learning. Yes 1.5 is stock for chevy. I did not relize 1.6 was stock for ford.
I think 3:55 gears will get him more top end. But I still think a different cam is in order.
Also could someone explain the difference between dual and single plane intakes? I know how to identify the two but I heard that one will produce more torque while the other will produce more hp.
Thanks, rocc

Shaggy- Do you think moving up to a 1.7 would help him out at all???

It wouldn't hurt but I don't think it would be worth the investment. If you are really looking to get more cam i would recomend either a custom mega $$$'s or a melling 24211 it is a REAL stout on the edge of steetable cam but then your intake will be lagging an open spacer would help some.

My suggestion would to be get the gears and an open carb spacer first and go from there.

Sound good. Thanks for the Help. ;)

Anybody?????:confused: