RPM range for a street car

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mshred

mshred

The Green Manalishi
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Hey guys,

I have been looking into what parts i will be getting for my 340 that i am building for my daily driver and was wondering about rpm operating range....There are ranges for parts from idle-8,000 rpm....my question is, if im trying to build a daily driver that will see some quarter mile time, what powerband area would i be looking to make power in? idle- 5,000, 1,500-6,500, etc? I know that all the parts should match eachother in their optimum rpm ranges, but just wondering what range i should be going for if i want to have fun on the street but perform well at the track....basically the most optimum range for a good street/ strip car

thanks
 
Alot depends on your gear ratio and if you will change the stall converter in your tranny. How far you want to take it, or not. Give us a few descriptive words on where you want your car to be at when your done.

The basic idea of a street strip cars RPM range is generaly;

Ave. Performer, 1000/1500 - 55/6000. (In this range you seem to fall.)
Heavier hitters start @ 2500 -6500. Most are here.
Getting serious is 3000 + - 6500/7000 rpm's. Few go here, but there out there!

A daily driver that see little track time would be happier with a cam that start it's power band at about 2,000 rpm or less. It will feel tame and drive like a regular car but really start to pick up @ around the advertised power band.

Let me give you an example or two;

This Crane cam page below has a host of info. On the bottom right, it has a box that has the min. and max as well as valve float rpm range of this cam.
Up top on the right, it gives a general idea of where the cam is at, basic rpm ranmge doesn't math the one below. The one below is the max ends of the cams performance while the box up top is the moderate everyday norm useage.
It has a few descriptive words to help in making a choice.
Mello driver;http://cranecams.com/?show=browsePa...-360 C.I.&partNumber=693901&partType=camshaft
Light performance, D/D.;http://cranecams.com/?show=browsePa...-360 C.I.&partNumber=693941&partType=camshaft
Mild performance D/D; http://cranecams.com/?show=browsePa...-360 C.I.&partNumber=693941&partType=camshaft
Home page; http://cranecams.com/

Heres comp cams catolog page, scroll down a tad and look for the Chrysler 273 - 360 page and click it. I like the comp cams pagesbecause it also recomends a stall converter, carb size and gear that work well.
But it is not a s descriptive as the Crane page;

http://www.compcams.com/Technical/CurrentCatalog/

Heres the Lunati home page. They took the time to make sections based on how the cam is to be used. I like the site. Nice cams, goo d pages, easy to see and understand. Cam timing info is even provided on the lower half of the page.

http://www.lunaticamshafts.com/
 
Nice post Rumble...

I kind of figure a street car to have a hydraulic cam, flat or roller. Low maint.

That in itself sort of limits the RPM range to the ~6500 max. Hard to get a good hyd. cammed engine over that point consistently. 340's like to wind it up because of the shorter stroke. Strokers are a good option, cost more $, gobs of torque. A 360 to build would have more torque, longer stroke than 340 and less expensive to build from the block standpoint.

The higher the RPM, the worse your idle quality becomes. It's another trade off.

If you built something to run in the 1500-6000 range, you'd have a pretty stout little street car capable of low 12's, maybe 11's, if gear/converter/hooking right.
 
for a car that's gonna be driven primarily on the street, you want torque. Lots and lots of torque. build the biggest motor you can (stroker). don't over cam or over port it. Use a RPM intake. Build it so the power drops off at 6000rpm. You'll have so much torque that you can use 3.55 gears instead of 4.30's. Another benefit of the low rpm motor is they last forever. My .02
 
mshred said:
i will take a look at the sites....I plan on atleast 3.73 gears for the rear and a stall converter maybe in the 2800- 3200 range, but i havent totally decided yet....the cam i will be using is the mopar purple shaft at this link

http://store.summitracing.com/partdetail.asp?part=DCC-4120653&autoview=sku

would this cam and the rest of my combo be overkill for the street in this range?
Click to expand...

If you are going to run a mech MP cam, run the .557 lift version. There are better cams IMHO. but that's a stout piece. Not really sure a daily driver is a fit for a mechanical cam, especially an old style loose lash set up.

Here's a link to some 360 builds:
http://www.geocities.com/alwest_83/dyno

The one thing on a SB that will help a BUNCH, is better heads. Either porting a set of irons or OOTB ede's. Some guys with 360's have picked up about 1 second in the 1/4 with nothing but a head swap, mid 13's to mid 12's.
 
Hey guys, i got the cam specs on the motor wrong.....the cam i am using has 284 duration, 0.484 lift and an rpm range of 2600-6000....the reason i am using this cam is because it is what i have and im not going to go change it....you guys are all suggesting strokers, new heads, etc. not happening....I know about all the performance gains from certain mods, but I am young and have limited cash so those things will not be happening for along time....rite now im keeping this cam and going with basic headers, intake and new carb....enough to keep a 19 year old kid happy on the street for a while....All i would like to know is what rpm range is optimal for fun in a street/strip car, not how to build my motor....thats something i can figure out myself

thanks
 
oh forgot to mention the motor has a .40 overbore currently and ported x-heads as well...
 
Looks good. It'll work fine in there.

The fellas were just suggesting a stroker for more torque and lower RPM's that help make a engine last while providing a ton of fun. They ment no harm. Just help.

Anyways, that cam will work great with the basic build up parts. RPM, 750cfm, super comp headers, etc..... The drill you probably know allready. Though I'm not sure of the stall converter to be used. I'm more of a 4spd guy myself. I like to row my own boat. The combo so far looks like it'll be a good street car that is capable.

I don't think it the best for daily driver though. It can be done and it is up to your wallet to power it daily. You won't see to good of a mileage aspect from it.

Have you decided on pistons, intake and such? OH, what car and year?
 
hey rumblefish360, i know no one ment any harm, but i just cant tempt myself into thinking of strokers....thats why i just want help with only what people think is the optimal rpm range of a street car....the car is a 71 scamp....the motor hasnt been opened up in 20 years so it will all be a surprise, but there are forged pistons in it and it has a .40 overbore (or .30, cant remember exactly since its been so long its been used)....probably going to go with flowtech headers since its all i can afford for now....what intake do you guys recommend for this setup? Also, how come you dont believe the car will be good on the street? i know its going to eat gas, but is the combo im planning going to be a real pig at the pump? i figured that if i went this route id be decent on mileage if i drove like a civilized person
 
Go out and get a set of Rhoades variable duration lifters. They "bleed down" at idle and take out about .025" lift and 15° duration at idle and pump up with RPM to give you the full lift and duration by 3500 RPM. I have used them for years and never had a problem with them on engines that have gone 250k miles on the build. Other companies make variable duration lifters, but Rhoades work the best. I have them in my 340 Cuda with the .484 284 cam and they work nice. It idles smoother and lower RPM than standard lifters, give you more low end torque, and most important of all BETTER FUEL ECONOMY AT STREET RPM.

I put them in a 318 with 9.2:1 compression 4 bbl and a stock 340 cam (the used one from my brothers Lil Red Express when he changed his cam he gave me his old one). With a stock 68 cast iron dual plane and a Holley 600 vac secondary carb and J heads with 1.88 intakes, I idled at 22.5" mercury ran a 10.5 power valve and got 17.75 miles per gallon with a 2.76 gear on the highway.

Basically, the Rhaodes lifters are like having an adjustable cam. You get your low end torque with out sacrificing top end horsepower.
 
Another issue on the street for most is traction as well. So if you are running your 500ft/lb of torque, you better be able to lay it down or you'll get left about every time...

If i had it my way, with my 3.91 and 3,500stall, i'd like to spin up to 6500-7000 if i had the cam and some port work to do it. As is with a 318 i have to baby it off the line running 295s in the back
 
mshred said:
....thats why i just want help with only what people think is the optimal rpm range of a street car....

....probably going to go with flowtech headers since its all i can afford for now....what intake do you guys recommend for this setup?

Also, how come you dont believe the car will be good on the street?

i know its going to eat gas, but is the combo im planning going to be a real pig at the pump? i figured that if i went this route id be decent on mileage if i drove like a civilized person
Click to expand...

Well, RPM range of what a good street car runs in is an open opinion. I gave mine above. I guess it kind of sets up a list on how one might see themselfs or where they might want to go. Kind of like into a bracket.

I'd look at a street dual plane. The RPM, Weiand Stealth, Sumitt racing has a similar intake, a 6 pak from MoPar.

The 4bbl intakes are easiest to tune and cheaper to purchase.

I believe the car will be a bit tuff on gas due to the cam converter and gear ratio combo.
The cams duration is getting a bit big for good gas mileage. The stall of the converter will waste some more gas until it becomes efficent in it's RPM range. Until it reachs it's operating range, it just wastes energy. Also the 3.73 ratio has the engine spinning more. More spin, more fuel used.

I see alot of fuel being wasted for a daily driver. But that all depends on you and what your OK with.
You could use a smaller cam and do a little better on mileage and still make power.
Also, the purple cams are a single pattern cam. Dual/split pattern cams can eek out a bit more from an engine and remain alittle more effcient in power production.

I say try the cam out and if your unhappy with the mileage, try a smaller split duration cam later.

What type of times are you looking to run?
 
those rhoades lifters sound cool, but i probably wont get into that for now...I was actually thinking of running an intake along the lines of a victor II or m1 single plane, but would that be bad for the street? Im fine with high gas consumption, since either way im gona be at the pump whether its a mild build or pretty serious....I was hoping with a 28-30" tire, 3.73 gears, manual shifted 727 with upgraded converter ( 2800 maybe?) and my 340 with matching intake, cam, carb and headers through a 2.5" exhaust would get me somewhere in the 13's at the least....if i could get low 13's high 12's i would be in heaven, but high 13's it what im hoping for at the very least...is this realistic? thanks so much for the help so far guys
 
Another two cents...

DO NOT run a single plain on a 340. Run an LD340, Performer RPM or an Air Gap. Single plains do not tend to make any torque down low.

Look at the link I posted earlier. It's for 360's but lots of the same general builds cross over.

Hard to go wrong with a XE268H, RPM intake, headers and a 750 holley
 
That Torkler II is a good swap meet part or entry level-ish drag intake that could do OK with a big-ish can and high converter and gears. This why it skips past it's weak point.
Same with the Victor performance wise.

Crackback has the idea.

I've run the Rhodes before. The best economy with them is found on smallish cams to begin with.
 
so i should probably go with a dual plane, like an edelbrock performer rpm? If i run the stock converter in my 727 (not sure what the stock stall is on a small block 727) would my mileage be any better? Im also looking at some proform street series carbs for my setup....has anybody ever used one, and what size do you guys recommend?
 
The RPM, per sai, is a best bet for the street. When I switched from my Torker II, there was no top end difference.

A stock converter would stiffle and cripple the performance of the engine until it reachs the RPM where it all comes in. But it would help only in a minor way.

Rumble said; Anyways, that cam will work great with the basic build up parts. RPM, 750cfm, super comp headers, etc.....
Click to expand...
You could do a 650 cfm carb. It would be a small limiter up top.
 
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