how much boost is "safe" on a daily driver?

[neckdemon]

so i am looking into what pulley combination i will eventually be going with. so my quesiton is, with the stock h/e on a car that i use a smy daily driver i want to know what's the best "compromise" of boost level i should go with that will mix power and reliability? in the end (at least for the forseeable future) my "power" mods will consist of:

jlt "rai" (already installed)
an h-pipe and cat-back
gears (haven't decided on the ratio yet probably 3.73's but i might go with the 4.10's, anyway the gears will probably be the last thing i do, so after all the additional power i can decide what gears i think i would like).
pulleys

in the end i would like this combo to give me the type of power that would bring my car into the 11 second zone, but still be a reliable daily driver. so what boost level should i look to be shooting for?

 

[o3SnakeBite]

If you want to be in the 11's all you need is eaither a 6lb lower or a 2.8 upper. If you want to go low 11's you can run a 2.8/2.93 upper with a 4lb lower. You should see about 17psi and that is good for a daily driven car. As far as gears, i always felt the 3.55's were a great gear. When you install the pulley your going to be burning the tires off in 1st and 2nd gear unless your running some really sticky tires. Plus it allows you to be in each gear longer

 

[neckdemon]

If you want to be in the 11's all you need is eaither a 6lb lower or a 2.8 upper. If you want to go low 11's you can run a 2.8/2.93 upper with a 4lb lower. You should see about 17psi and that is good for a daily driven car. As far as gears, i always felt the 3.55's were a great gear. When you install the pulley your going to be burning the tires off in 1st and 2nd gear unless your running some really sticky tires. Plus it allows you to be in each gear longer

well i'm running nitto 555r's in the back. they seem to hold well now (of course it's only a stock car except for the RAI). those will be the tires i'll be running all the time though. i've driven them alot on fox body's i've had and i like them. i guess after all is said and done i will decide if i like the 3.55's or not (which is why i'm waiting on the gears till last). i was thinkning of going with the 3.1/2lb combo which according to that chart on modular fords would net me about 14 psi, which i was thinking should be about as far as i should go w/o cooling mods. you really think 17 psi is reliable? that sounds like an awful lot of boost. wouldn't i need to upgrade the fuel system for that? you'll have to forgive my ignorance on these matters. i've never owned or modded a supercharged engine. all my experience is with n/a pushrod engines

 

[04torchred]

well i'm running nitto 555r's in the back. they seem to hold well now (of course it's only a stock car except for the RAI). those will be the tires i'll be running all the time though. i've driven them alot on fox body's i've had and i like them. i guess after all is said and done i will decide if i like the 3.55's or not (which is why i'm waiting on the gears till last). i was thinkning of going with the 3.1/2lb combo which according to that chart on modular fords would net me about 14 psi, which i was thinking should be about as far as i should go w/o cooling mods. you really think 17 psi is reliable? that sounds like an awful lot of boost. wouldn't i need to upgrade the fuel system for that? you'll have to forgive my ignorance on these matters. i've never owned or modded a supercharged engine. all my experience is with n/a pushrod engines

Hell don't spend all that money on a lower and upper if all you want is 14psi. Just run a 2.8 upper or a 8lb lower. I am going with the 8lb lower for my daily driver.

 

[racebronco2]

Hell don't spend all that money on a lower and upper if all you want is 14psi. Just run a 2.8 upper or a 8lb lower. I am going with the 8lb lower for my daily driver.

isn't the price the same with whatever upper/lower combo he runs

i know a few people who run mid 11's (one of then runs 11.5 and the other runs 11.7)with no lower, 2.8 upper, cai, tune, x-pipe, cat-back, dr and 4.10 gears.

 

[C.K.]

A guy locally ran an 11.57 @ 121 with 1.81 60' with just a 2.76, intake, exhaust, and et streets. It can be done. Lower pullies add a lot of torque, so DR's will certainly be helpful. You shouldn't have any problems with daily drivabilty. If you end up going lower pulley, I would suggest the 2.93 or 2.80 upper and 4lb lower. That will give you good torque.

 

[BO TY KLR]

See sig. Daily driven 9 months out of the year.

 

[04SNK390HP]

daily driver here, unless snow is on the ground then I just take it slow, lol but true. See Sig

 

[04torchred]

isn't the price the same with whatever upper/lower combo he runs

i know a few people who run mid 11's (one of then runs 11.5 and the other runs 11.7)with no lower, 2.8 upper, cai, tune, x-pipe, cat-back, dr and 4.10 gears.

I mean if he is just after around 14-15psi then he only needs a single pulley, not an upper/lower combo. Why spend all that money on a 3.1/2lb when you could get the same boost with just one pulley and use the extra cash for other stuff? Just my take on his situation

 

[rmgtc01]

I heard that lower pullies beat up the casing because their is no balancer on their. I don't have much experience with the lowers, but a local tuner was explaining why he was against much more than the typical mods and an upper/port/tune.
Any opinions?? Longivity??

 

[BO TY KLR]

I heard that lower pullies beat up the casing because their is no balancer on their. I don't have much experience with the lowers, but a local tuner was explaining why he was against much more than the typical mods and an upper/port/tune.
Any opinions?? Longivity??

This is one of the main reasons I haven't went with a lower. I think the stock lower cage was designed there for a reason. To support the end of the crank for that load of the blower belt. I know ,I know, everyones got one without probs but with my luck I'll have probs. Really wish you could keep the cage when adding a lower.

 

[I-CAN-STANG]

BF 2.76 upper = 14psi = safe for daily driving! :-D

 

[cdh027]

This is one of the main reasons I haven't went with a lower. I think the stock lower cage was designed there for a reason. To support the end of the crank for that load of the blower belt. I know ,I know, everyones got one without probs but with my luck I'll have probs. Really wish you could keep the cage when adding a lower.

I'd like to hear more about this. I was suppose to install my lower this weekend, but..................

 

[Chonger]

There are tons of different combinations available. The easiest one is a single 2.80/2.76/2.75 upper only and be done with it. No need to mess with an alternator pulley or lower pulley. Just get the upper and auxilary idler.

With a good tune this should get you in the 450-460 RWHP range and be 100% reliable. Adding a lower will net more TQ but this is the simplest answer.

I've had this setup for over 3 years and not one single issue.

 

[rmgtc01]

I'd like to hear more about this. I was suppose to install my lower this weekend, but..................

I am not sure of the technical details (maybe someone can chime in), but basically it just beats up on the motor more, and more vibration/friction without the balancer. Yes, a lot of people have them on their cars but we have not encountered a mass number of high mileage cobras yet. So far the upper pulley seems like a safe bet. I am one example, although I didn't do it till 40k mi. The word around is that anything more than mentioned above will have serious wear and durability issues. Not sure how long people plan on keeping them, but they may or may not see 70k +.

How many people have 20K + on thier cobras with most of the goods and a lower pulley as well and/or higher mileage cobras with it?

 

[blackvenom77]

I am not sure of the technical details (maybe someone can chime in), but basically it just beats up on the motor more, and more vibration/friction without the balancer. Yes, a lot of people have them on their cars but we have not encountered a mass number of high mileage cobras yet. So far the upper pulley seems like a safe bet. I am one example, although I didn't do it till 40k mi. The word around is that anything more than mentioned above will have serious wear and durability issues. Not sure how long people plan on keeping them, but they may or may not see 70k +.

How many people have 20K + on thier cobras with most of the goods and a lower pulley as well and/or higher mileage cobras with it?

Really haven't thought of it that way. Maybe I'll skip the lower with my new KB set-up. :shrug:

 

[cdh027]

Seriously, anyone that has in-depth knowledge of the consequences of unbalancing the crank pulley please chime in. I know I'm not the only one waiting to hear the facts ????????????????

 

[04torchred]

Do you guys honestly think Ford balanced every Cobras rotating assembly? Heck no, this would require work and I bet there is not one whole drilled into the counterweights on a Cobra crankshaft. The crank will be a zero balance or neutral balance. If it wasn't throwing on a steel flywheel would also be messing stuff up and require a rebalance. I will let someone else chime in as I have not installed my Metco lower yet so I don't know what is all coming off.

 

[Crowley]

Daily driver here as well ..

Crowley

 

[neckdemon]

hmmm, i didn't think about it that way. but, isn't there a crankshaft damper there that balances it out? does make me think twice about adding a lower though. i was going to do it for the extra torque, instead of just going with only an upper. but i'm not too sure now. i'll have to hear a little more input on the subject.