Help with a 306 build

[Jay Rod 5.0]

I have 3.73 gears,Mac equal length shorty headers,Mac h-pipe,Flowmaster catback,Underdrive pullies,Mac coldair intake,NGK wires and plugs,aluminum radiator and electric fans and 93 cobra intake and 70mm throttle. I want to do a 306 with a 125 dry shot of NOS what do I need..and please dont leave anything out because to be honest I have no clue. I know Mitsubishi not Mustangs. Like a bigger mass air..how do I know what to get. Do I have to get rid of my cold air intake? I know with a Supercharger you have to get rid of the underdrive pulleys..do I with NOS?? What octane do I need to run to spray a 125 shot?? To anyone that helps thanx...I just have no friends that like Mustangs(all imports).

[unstopablestang]

what are you gonna do with the stangi use to bulid up my old cvic i have always liked muscle anywasy bac to ur stang ill ask my dad and ill get back with you or you can give mps a call

[Herbstang]

Give this a read http://www.mustangevolution.com/articles/20077/

[bbunt302]

First of all, I'd recommend waiting on the nitrous. Personally, I'd build a solid N/A motor first.

You've already got a decent intake with the Cobra intake. Next, look into a set of heads. If you want to get out cheap, look for some GT40 heads. If you want to make a little more power, look for a set of either Edelbrock, Trick Flow, or even better, AFR aluminum heads. A good set of aluminum heads with a decent cam (I'd recommend a custom) and you're existing intake should be good for 300+ rwhp with all the supporting parts.

Now for the supporting parts... You'll probably want to go with a 75+ mm mass air calibrated for 24# injectors. Then of course, the injectors to go with it. You'll probably want to go ahead and upgrade to a 255 lph fuel pump while you're at it.

After all this, you should have a nice, daily-driveable 300+ rwhp vehicle. Then if you decide to go ahead with the nitrous, you'll be looking at well over 400 rwhp.

Depending on the mileage of your engine, you may also want to strongly consider a rebuild during all this, especially before the nitrous. Really, when you have it apart putting the heads on is the best time. If your lucky like I was, a hone and new rings, bearings and freeze plugs may be all you need. The factory bottom end will hold up just fine to a 125 hp shot. But, if you're unlucky and need to bore out to a 306, a nice set of forged rods and pistons always helps.

For the octane question, I run 93 octane in my '90 simply because I'm running 17-18* degrees of timing advance. With the nitrous, you'll probably want to go ahead and run 93 as well. Also be aware that you will need a colder spark plug than a N/A car.

[Matthew]

If you are going to rebuild it into a 306 anyway, it's a good idea to be thinking about heads, cam, and intake to go with the rebuild. I personally think the Trick Flow Track Heat's are the best value for money heads out there for a regularly driven 5.0. A manifold like the Performer RPM, or even the Ford Cobra or Pro Products Typhoon would probably be a good choice. For a cam, I would suggest calling Comp and talking to their cam help line about your project. Something like the XE274HR is a good hydraulic roller that would work pretty well for you. I personally ran a Trick Flow stage 2 in this kind of combo, but with a stock 90 short block, and it worked fine.

Long tube headers would be better than your shorties, but if you have the exhaust already it will work ok.

Its also not a bad idea to think about an SFI balancer like the Powerbond, and a quality clutch. My suggestion for clutch would be the McLeod 800 series, and I always suggest a blow proof bellhousing in case you blow it up, especially with Nitrous.

Others have suggested 24# injectors, which will be fine for this iteration of your car, but if you plan to keep going like most guys do, I would recommend bigger injectors and a calibrated MAF. I personally ran 30# injectors in this kind of combination and they lasted until I ultimately upgraded the whole fuel system including 83# injectors. 30# or 42# would be my suggestion. If you think you might supercharge it later, 42# would be the better choice.

As far as nitrous goes, I normally advise against it in a street car because it's too easy to do something stupid like light it up in overdrive, then it's game over. If you are going to run nitrous though, I would suggest a wet system for a 125 or 150 shot.

If you are going to build the short block, you should think seriously about where you are going with the car before you decide on the compression. If you are really going to stay NA or rely on nitrous, you might want to think about as much as 11:1. If you were going to build it for a supercharger, 8.5:1 would be a better bet. If you are just not sure what the future holds, then I would suggest 9:1. That kind of setup will stay together even if you decide to supercharge it later.

Good luck.

-Matthew

[bbunt302]

If you do decide to run a Comp Xtreme Energy cam, just be aware that they can quickly destroy valve springs. They have absolutely ridiculous (in a good way) ramp rates, so be sure to upgrade to a valve spring that is rated for well over the advertised lift of the carm.

[Matthew]

Quote: Originally Posted by bbunt302 If you do decide to run a Comp Xtreme Energy cam, just be aware that they can quickly destroy valve springs.

Those cams are fine. Use springs that meet Comp's specs for lift, seat pressure, and spring rate. If you use the Trick Flow Track Heat heads, they come with an upgraded spring package that will work fine with a cam like the XE274HR.

-Matthew

[bbunt302]

Quote: Originally Posted by Matthew Those cams are fine. Use springs that meet Comp's specs for lift, seat pressure, and spring rate. If you use the Trick Flow Track Heat heads, they come with an upgraded spring package that will work fine with a cam like the XE274HR. -Matthew

Yeah, they're great. I have one.

But just make sure that you don't use a set of cheap valve springs, especially with the higher lift cams. If your springs are rated for .550" lift (like the springs that come on the AFR 165s), you don't want to run much more than a .512" lift cam. I really wish I would have went ahead and upgraded the springs on my 165s for my XE270HR (.512"/.512"). They are much harder on the valve springs than most cams with comparable lifts due to their Xtreme Engerginess.