Flowmaster Exhaust Currently Too Quiet !?

[FoxMustangLvr]

You seem to have a plan and pretty much know what you want so I'm not going to bore you with the "go aluminum" rant. Should be a fun street car when your all done. 3.55's with a manual transmission should be very user friendly while still waking up the car. I just went from 3.08's to 3.73's (again) and I'm very happy but I also do very little freeway driving (more like never).

 

[A5literMan]

I've had 3.55's twice and presently run 73's. Either one are good for what you're talking about. Don't be afraid of the 73's they hardly change your mpg and cruise rpm fwiw.

 

[Btrainfiveoh]

Glad to hear that your happy with the sound and performance. Please ditch the 87 octane and spring for the 92 octane to go with the 13* timing.

I have no detonation with runnin 13* on 87 octane... I've heard you want to run the least amount of octane at the max timing advance without detonation for max power.

 

[Btrainfiveoh]

You seem to have a plan and pretty much know what you want so I'm not going to bore you with the "go aluminum" rant. Should be a fun street car when your all done. 3.55's with a manual transmission should be very user friendly while still waking up the car. I just went from 3.08's to 3.73's (again) and I'm very happy but I also do very little freeway driving (more like never).

Yeah I know aluminum heads is deff the way to go, but trying to keep it budget friendly. Aluminum heads here after I'm said and done are going to run me 2500... Porting the stockers with the valve spring change... 3-500 tops. Obviously I won't make the same performance gains, but like you said... With gears and that work, it should be a fun street car. 3.55 to 3.73 that's what I'm torn between right now, I deff do hwy driving ...

 

[A5literMan]

You probably would like 3.55's the best. If I remember right they cruise around 2100 rpm's on interstate. 73's are around 23-2400 at 70-75mph

 

[FoxMustangLvr]

$2,500 for aluminum heads? Where are you at?

Also, I've never heard of low octane doing anything to increase power especially when advancing timing. What is your source?

 

[Btrainfiveoh]

$2,500 for aluminum heads? Where are you at?

Also, I've never heard of low octane doing anything to increase power especially when advancing timing. What is your source?

The shop I've gotten some work done from. Mopac (out here in canada, BC) and afr heads or trickflow heads are about 2000-2400, add in pushrods, lifters, rocker arms... As for the octane rating, I was told if it's not detonating there's no point in adding octane. They build street car to strip cars.

 

[squeak93]

Run premium if advanced timing. Trying to skirt by with low octane fuel and "pray" it doesn't ping is just a recipe for disaster.

Use good branded 91 octane and keep the timing around 13-14 (on a stock car there is no benefit to getting every degree you can).

 

[Btrainfiveoh]

Run premium if advanced timing. Trying to skirt by with low octane fuel and "pray" it doesn't ping is just a recipe for disaster.

Use good branded 91 octane and keep the timing around 13-14 (on a stock car there is no benefit to getting every degree you can).

Hmm, that's odd as why I'm getting so many mixed opinions. I was told by them you'll actually decrease performance if you advance timing to 12-13 and run 91, the goal is to run the highest timing with the lowest octane (87) safely. If it's detonating, turn back on the timing. And as of right now, there's no pinging or detonation... Mind you I have no issue running 91, I was just told that with a stock 5.0 it doesn't make sense... Now if the compression was changed or timing was advanced 14-16 then yes, 91 octane is required otherwise there'll be detonation. But I'm curious to know what others say as well. If it is true, then I'd like to go back to that shop and find how why and how they recommend that. Considering, like I said, they build and work on countless street/strip cars. There one of the only good speciality shops in the area that don't charge a stupid amount just because of their name.

 

[CarMichael Angelo]

I agree w/ your shop. The primary function of higher octane is to slow down the burn rate of the fuel. Commensurately, 91, or 93 octane gasoline is slower to combust than 87, and as a result lower efficiency.

Lower efficiency, less power , blah, blah, blah.

Now, as to how much difference can be gained by better octane and bumped timing over stock timing and standard 87 octane, I can't comment.

This is typically a larger problem when considering going to the next level where 93 is barely adequate, and race fuels (100 octane or higher) become the alternative .

 

[A5literMan]

I always so better performance with 13-15* timing and 91-93 octane fuel. I've ran 12-13* on 87 without any problems though(but remember you can't always hear detonation)

 

[cobra10494]

Why bump the timing and run 87?????

 

[Btrainfiveoh]

Why bump the timing and run 87?????

Because, like I said, according to the shop, can't remember his exact words but basically he said if you're bumping the timing up a bit and adding a higher octane fuel, you're contradicting it... You won't make a gain. You want to bump the timing a bit over stock and be able to use the same octane fuel the car was meant to run on(87) ... That's where you'll get max performance. Stock timing is 10* on these, so running 13 shouldn't be too big of a deal, but after hearing so many people say put premium if you're advancing timing it's got me all confused.

 

[mikestang63]

Because, like I said, according to the shop, can't remember his exact words but basically he said if you're bumping the timing up a bit and adding a higher octane fuel, you're contradicting it... You won't make a gain. You want to bump the timing a bit over stock and be able to use the same octane fuel the car was meant to run on(87) ... That's where you'll get max performance. Stock timing is 10* on these, so running 13 shouldn't be too big of a deal, but after hearing so many people say put premium if you're advancing timing it's got me all confused.

The reason you need to run premium fuels these days is mostly due to the ethanol added, which effectively lowers the octane rating. Two fuels with the same octane rating but one blended with ethanol will have worse performance and not support as much timing in my experience. It also depends on the compression of the engine. A higher compression motor requires more octane as well.

 

[Stang D]

Don't be afraid of 3.73s. I ran them for years before my 4.10s went in. You can still get very good mpg with a 5 speed and 3.73s There is no better performance mod than gears IMO.