What combo to use??? 450 rwhp goal...

[OiDALE]

I will start off by stating all thats done to the motor: Its a 1991 GT, im the third owner-about 60k original miles, stock 2.73 gears which I will keep them (gets great mpg)...I bought it bone stock and now it has:

-bbk cold air into the fender with bbk 75mm tb (also have PP 70mm)
-Professional Products 76/or bigger mm egr spacer
-MSD wires, coil cap and rotor
-Mark 8 electric fan
-3g alternator
-Optima redtop battery
-smog delete but with working a/c
-1" 3/4 long tubes into 3" collector, 3" tubes into pro-chamber, 2" inch pipe into 2 chamber flowmasters with pro-street dumps
-About 120 rwhp nitrous wet shot (drilled egr with NOS fogger)

planning on moving the fogger onto the front side of the upper intake after the egr at one of the opennings for vacum? "Holley systemax"

Not installed:
-Professional Products 70mm TB
-Professional Products 70mm EGR spacer
-C&L 80mm meter calibrated to 30#
-Holley Systemax 2 with spacer (upper and lower)
-24 # and 30 # injectors
-fuel pressure regulator
-Walbro 190 fuel pump
-RPW aluminum rocker arms 3/8 1.7
-Planning on Buying Underdrive pulleys
-Planning on buying MSD 6AL

My question is which combo should I use with my stock motor and heads for right now but will upgrade the heads in the near future adding a cam too. Also down the road I would like to ad a blower in substitude of the nitrous.

My goal would be 400/450rwhp when all is done keeping the lower untouched/stock. But for now I would like to go peice by peice with out spending unneccessary money/backtracking and keeping what I have or selling and getting what I need. The car is and will be a street car, I dont take it to the drag strip I just like having fun on the streets and slapping a confused face on other cars. Would like the power to come on as low as possible and scream up high (remember, I will maintain 2.73 gears) I want her to plant me into the seat at any gear and keep pulling extremely hard, looking for some "g's"

(((The car is completely stock besides everything that I mentioned and the extra parts that I listed. So please tell me if im heading into the right direction or should I "SELL" off certain items to get "WHAT" in there place? Thanks to all that will help...)))

Also, wanted to ad: I have a buddy that will sell me a pair of ported victor SR. heads really cheap but I was thinking why go through the expense and trouble of installing them if I can save a bit more money and buy a very nice set of heads later on...Any thoughts???

 

[LarsD]

If you plan to keep those gears, then I would run a turbocharger. You will have a hard time hitting 450hp at the wheels unless you do an H/C/I also though.

 

[90lxcoupe]

The 2.73s are going to make the car a dog, no matter what, and may actually hurt you in the mileage department unless you plan on driving at 80 mph on the highway all the time.

There are about 35 different combinations that will get you 450rwhp with a stock block, use the search feature and google, read about different setups and use your judgement on what one will suit you best.

I will say it again just because, keeping the 2.73 gears is not a good decision.

 

[Kdubslugga]

Just about any combo with a 125 shot will net you 400 plus pretty easy.

 

[OiDALE]

Ok...I have been led to this site a few times now: http://www.on3performance.com/mustang5.html Does anyone have any insight or knowledge of someone with it? Seems that $1500 for an almost complete kit neting those numbers is a no brainer...Thoughts?

 

[LarsD]

Ok...I have been led to this site a few times now: Turbo Kits for Ford Mustangs Does anyone have any insight or knowledge of someone with it? Seems that $1500 for an almost complete kit neting those numbers is a no brainer...Thoughts?

The quality of their kits is pretty hit or miss from what I understand. Some people are really happy with them, some aren't. Kinda depends I which day the kit was built I guess. B&G kits are much better (from what I have been told).

 

[Dino Dino Bambino]

If you plan to keep those gears, then I would run a turbocharger. You will have a hard time hitting 450hp at the wheels unless you do an H/C/I also though.

You definitely need H/C/I upgrades plus forced induction to get 450rwhp from a stock 302 short block. If you keep the stock 2.73 gears, you'll need all the low rev torque you can get so I'd suggest a Kenne Bell twin screw supercharger rather than a turbo or a centrifugal.

 

[FastDriver]

He's probably not going to hit his 450rwhp goal with a KB, though it may be possible.

Anyway, I don't know why you guys are beating him up over the 2.73s, and I certainly don't see how they HURT his gas mileage. The C5 corvette I've got gets damn good gas mileage and uses an even taller overall gear (.5:1 6th gear with 3.42s = 1.71 vs. .675:1 5th gear with 2.73s= 1.8x)

I guarantee a mustang is not going to get its best mileage at anything over 55mph even with 2.73s.

Chris

 

[OiDALE]

Thanks Fastdriver,
Vettes are a whole different animal (weight/power ratio)= 28/30 hwy mpg's...I get pretty decent mpg's at the moment, drove 300 miles round trip about 3 weeks ago averaging 80mph and got 19mpg. Thats why I love these gears. If I did the same mph with lets say 3.73, I would be lucking to get 14mpg...Also note that at 80mph my rpm is at 2200...Now thats what im talking about. So,

I do think for now I will keep my stock heads/bottom end and will install my 1.7 rockers along with the Holley systemax 2, 42# injectors-80mm calibrated mass, 70mm tb, 255 pump, add some underdrive pulleys, msd 6al and fork out the $1500 for the turbo (when time and money permits) and then get it tuned. I should from what I have read be at around 400-450 rwhp and tons of torque. Any thoughts or, Is there anything else I should consider or be aware of?

I beleive but really not sure of, superchargers were built to make power not increase fuel effeicency unlike turbos which were built in planes to cross large areas with the same amount of fuel. Like I said im not 100% sure but seems like a turbo car when not at 100% boost gets pretty good mpg"s...So I think with the turbo at low boost I would be pretty close to my goal and still get decent mpg's especially with my 2.73's...

 

[OiDALE]

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[FastDriver]

With stock Heads and cam, I don't think you're going to see 400+ rwhp without a lot of boost (15 psi range).... At that kind of boost, maybe you'd see 400. Buyer beware on those On3 kits. Do your research. Remember that you get what you pay for.

Turbos will probably not cost as much in fuel economy as a blower, but they aren't free, either. They will decrease mileage overall.

If I were you, I'd invest in a nice set of heads and a cam, first. From the sound of it, you're already running the other things you need. Heads and cam will probably pick up 60-80 rwhp. That would be the equivalent of a turbo on low boost, but would have the added benefit of simplicity (installation, tuning, maintenance, etc...). It will also give you the time to research the right turbos.

If you're stuck on turbos, at least get someone who has done the kit you're planning to purchase before you get something you don't want. That way you'll know what to expect.

Good luck,

Chris

 

[90lxcoupe]

Thanks Fastdriver,
Vettes are a whole different animal (weight/power ratio)= 28/30 hwy mpg's...I get pretty decent mpg's at the moment, drove 300 miles round trip about 3 weeks ago averaging 80mph and got 19mpg. Thats why I love these gears. If I did the same mph with lets say 3.73, I would be lucking to get 14mpg...Also note that at 80mph my rpm is at 2200...Now thats what im talking about. So,

19mpg isnt anything to brag about with a stockish motor mustang. A friend of mine gets mid 20s with his HCI car and that is mixed city and highway. My opinion is the gear could either help mileage a little bit or it will be the same. You arent doing fuel economy any favors by lugging the car around at those low rpms and the motor has to work harder to get the car moving, like when you try to pass someone on the highway.

Hell, my car with a semi-seriously built motor gets 14-15mpg with 4.30s an a 28'' tire. If you have 3.73's and bolt ons the car should average 20+mpg.

 

[FastDriver]

I don't know 90. I was able to pull 38 mpg out of my vette by cruising at just above idle. Did the same in mom's '04 Excursion to pull 23mpg out of it. That's like saying shifting into your last gear won't get you better gas mileage because you'll be lugging the motor. Well, if you're lugging the motor, then speed up. You won't be lugging at 55.

I agree with the 3.73s comment. I got 22mpg on a 4 hour drive to my buddy's with my current setup that's running 3.73s, and wasn't really trying.

I also agree that 19mpg isn't anything to brag about. I'd be willing to bet that car CAN do a lot better than that, though. Especially considering he said he was doing 80. Foxes aren't aerodynamic. I believe the same car is going to be in the high 20s driven conservatively.

 

[FastDriver]

In all honesty, I can see the appeal of beefing up the power, but wanting to keep the same rear. It doesn't sound like he's out to be the most competitive street car from a stop light. It seems he just wants to significantly boost performance without greatly imposing on economy.

 

[90lxcoupe]

I don't know 90. I was able to pull 38 mpg out of my vette by cruising at just above idle. Did the same in mom's '04 Excursion to pull 23mpg out of it. That's like saying shifting into your last gear won't get you better gas mileage because you'll be lugging the motor. Well, if you're lugging the motor, then speed up. You won't be lugging at 55.

You will be lugging the motor at 55. The rpms with a 2.73, .68 5th, and a 225/55r16, the RPM at 55mph is just over 1300, i would call that lugging. Even at 80 the RPM is under 2000. To speed up effiecintly at either of these speeds, especially with a bolt on car, you are going to have to drop into 4th gear. If you stayed in 5th and tried to pass someone, increasing the speed from 55 to say, 75 mph, it will take much more effort from the motor and IMO you are using more fuel this way.

 

[LarsD]

I have to agree, 19 isn't that great. My 91 with its old worn out 302/3.55's could hit 18 with the A/C on. If I didn't beat on it a bunch.

 

[OiDALE]

Thanks for all the input...Yeah, 19 isnt much to brag about but i was averaging 80 that means I hit 90/95 and came down to 70 where the radar went off. O and yes the a/c was on the whole time. Also, consider that I have 17x9 fronts 255/40 and 17x10 rears 275/40's. I have gottten 22 on hwy around 75mph with the a/c with 93 octane. This time around I choice to try out 87 and it did a bit worse. I get decent mpg's on 93 around town even with the gears. No, I do understand that tall gears are much better around town. My wifes old lx 5.0 with 4.10's (yes wifes) did much better around town then my car. But I do mostly hwy driving and beleive me the 2.73's really pull hard on spray (theres a few turbo g35's, m3's, mazda 3 turbos, and some sn's that would agree).

Trust me im all about a great set of heads but for the money you really cant beat the turbo set up. And besides filling up the bottle every week or too gets to be expenssive and I dont even go to the track, lol. Its all toying on the highway. Dont let FHP read this, haha...

 

[FastDriver]

You will be lugging the motor at 55. The rpms with a 2.73, .68 5th, and a 225/55r16, the RPM at 55mph is just over 1300, i would call that lugging. Even at 80 the RPM is under 2000. To speed up effiecintly at either of these speeds, especially with a bolt on car, you are going to have to drop into 4th gear. If you stayed in 5th and tried to pass someone, increasing the speed from 55 to say, 75 mph, it will take much more effort from the motor and IMO you are using more fuel this way.

I guess our definitions of lugging differ then. On a stock cam, I see nothing wrong with 1300 RPM. In fact, that's probably very close to optimal cruising RPM.

I would test your premise that accelerating around somoene in your final gear would use more fuel. Don't get me wrong, I wouldn't care to test that theory on a 2-lane, opposing traffic road, where I'd probably drop to 2nd or 3rd to pass because I'd prefer to get it over with quickly. On an interstate, where passing time does not pose risk, I'd stay in 5th if trying to conserve fuel. I'd also stay at partial load where the computer wouldn't be trying to significantly richen the mixture. Keep in mind, that from a physics standpoint, the lower the RPM, the more time the motor will spend extracting power from the air/fuel charge in each combustion event.

 

[FastDriver]

Thanks for all the input...Yeah, 19 isnt much to brag about but i was averaging 80 that means I hit 90/95 and came down to 70 where the radar went off. O and yes the a/c was on the whole time. Also, consider that I have 17x9 fronts 255/40 and 17x10 rears 275/40's. I have gottten 22 on hwy around 75mph with the a/c with 93 octane. This time around I choice to try out 87 and it did a bit worse. I get decent mpg's on 93 around town even with the gears. No, I do understand that tall gears are much better around town. My wifes old lx 5.0 with 4.10's (yes wifes) did much better around town then my car. But I do mostly hwy driving and beleive me the 2.73's really pull hard on spray (theres a few turbo g35's, m3's, mazda 3 turbos, and some sn's that would agree).

Trust me im all about a great set of heads but for the money you really cant beat the turbo set up. And besides filling up the bottle every week or too gets to be expenssive and I dont even go to the track, lol. Its all toying on the highway. Dont let FHP read this, haha...

Ok, good luck then.

 

[OiDALE]

In all honesty, I can see the appeal of beefing up the power, but wanting to keep the same rear. It doesn't sound like he's out to be the most competitive street car from a stop light. It seems he just wants to significantly boost performance without greatly imposing on economy.

You pretty much nailed it...