Supercharging question

[monsterstang70]

I have a 79 mustang with a 302 with about 40k on the engine rebuild. As far as I know, it have stock internals. My question is how much boost can I put into the engine before the pistons crank or I throw a rod? The supercharger that I plan on using now is nothing too serious, just a Holley 174 Powercharger.
Thanks
Jhery

 

[sms73511]

The 174 can be a pretty stout charger. It's more than enough to send a 302 to lah lah land. Keep it in th 5-7 range good gas,good tune,good tires. It's not a centrifugal charger so your bottom end increase is going to be more substantial than say a a-trim. freshen up the aod , u-joints rear-end.. It will keep you happy for awhile

 

[Daggar]

Sounds like a sweet setup. You have it installed already? Post some pics when you get there.

 

[ponyboy19]

IMO it's not so much the amount of boost but rather the amount of power the engine makes. Not sure what the internals are that your using but for a nice safe power range on a stock block I'd keep it in the 380-400 rwhp range with a solid tune.

 

[monsterstang70]

From what I been told, the stock internals of a 79 302 is all cast but my car didnt come with a 302, it came wit a 3.4 liter or sumthing like that so i might luck out and get some forged parts thrown in the mix lol. I got to get the head ported, get a decent cam, do valvesprings and other valvetrain parts and the get the supercharger and it'll be good to go lol.
Also how big of a carb should I use? So far on the car is a holley 650 i think.

 

[BullittStangV8]

sorry to bring up an old post, but im dropping a 5.0 create engine into my 65 coupe, and im trying to find a roots blower that will bolt on to the 302, and keep the carb. I keep only finding info aboutthe holley 174. Can anyone give me some info on it? how many lbs? how much do they cost, and who sells them?
The create engine comes with 9.0 compression, so it should be safe with a blower.
Mike

 

[giddyup306]

I've seen people go as far a pro charger 17/14 setup on a 100% stock bottom end.

stangV8 do you have aluminum heads? If not you might not get by with pump gas and boost. Also 9:1 is pretty high for a boosted engine however with a good intercooler and high octaing fuel I think you can get by. Anyone else have some input?

 

[BullittStangV8]

the engine will have aluminum heads. The engine is the ford racing create engine 302 w. Aluminum GT-40 heads. it comes stock with 340 hp, 305 ft trq. Im happy with those numbers, but if i could charge it i would be even happier. If the compression is too high to charge it, then clearly i dont want to be destroying a new engine.
Mike
p.s random question:does anyone know how high these engines can spin? I know it will stop making power after it maxes out my manifolds power band, but what is the max safe rpm?

 

[giddyup306]

The crate engine with the cam should make max power around 6500 RPM . Should be able to spin a few hundered RPM more.

Also you could still boost the car just be carefull. I run 11.5:1 on the street. I have a 3 stage retard with retard selector. This way I can controll timing if I get some bad gas. I'm also picky as to what fuel I use. I also try and keep my foot out of it as well.

 

[BullittStangV8]

wow thats a really high rpm..My modular doesnt even rev past 6200. thats a huge difference from my old 4500 rpm max in the 289.
As for A/F, id have to get on a dyno to make sure my carbs tunede right. So i could be safe with 9.0 compression as long as i keep a safe A/F? I wont be snapping rods due to too much power correct?
Mike

 

[giddyup306]

wow thats a really high rpm..My modular doesnt even rev past 6200. thats a huge difference from my old 4500 rpm max in the 289.
As for A/F, id have to get on a dyno to make sure my carbs tunede right. So i could be safe with 9.0 compression as long as i keep a safe A/F? I wont be snapping rods due to too much power correct?
Mike

The only reason why your modular dosen't spin any higher is because ford puts a rev limiter on ther at 6250 rpm. How many pounds of boost do you plan on running? Also the 289s they had in the shelby cobras would spin ~9000 rpm.

 

[BullittStangV8]

I know theres a reve limiter, but if you remove them,and spin the engines higher then around 6500, things start to break. the just arnt ment to be reved that high on a stock engine.
And not allotta boost, 5-6 pounds?
Mike

 

[Daggar]

Mike,

I imagine that the engine you're putting into the 65 is going to be carbed. I also saw that you were talking about the Holley positive displacement blower. On a crate engine with a 9.1 compression you will be able to run 8lbs of boost with no inter/after cooler and the correct air/fuel ratio and timing with no problems at all. I've seen cars run similar setups run 11 lbs of boost (requires careful tuning) on 93 pump gas and make all kinds of power. I wouldn't concern myself too much about the heads being cast or aluminum. It's true that aluminum heads disipate heat energy faster than the cast pieces do but cast heads also spread the heat out much more evenly and transfer heat back to the block and cooling system better than aluminum does and isn't as prone to hot spots. About the only real advantage to having aluminum heads on a roots type blower sitting ontop of the motor is the weight savings.

Edit: One other thing of note is that the air charge temp on positive displacement blowers is considerably cooler than that of a centrifugal and the better your engine cooling system is the more efficient your blower will be.

Just to give you some idea: I'm currently running the 2.2L Kenne Bell ontop of a pretty much stock short block. It's and 86 with flat top pistons and compression is roughly 9.2. Timing is hovering right around base at 11 or 12* and the whole things runs it's best on 90 and 91 octane gas. Granted there will be some diferences with the carbed setup as far as tuning the AFR etc. but if you run a conservative setup to begine with and fine tune it for power I'll think your setup will do great things.

 

[BullittStangV8]

Dagger,
Thanks for the info. I wouldnt be planing on going over 6-8 lbs of boost. That seems like i could be over 410 or so fwhp. That would be pretty fun in a light little 65. I dont think the 174 is intercooled. Id have to get a bigger radiator to keep up with the added power of the supercharger over just the 5.0. I think it would be prettty sweet to have a 65 coupe with a 3 inch cowl, blue with white racing stripes with a blown 5.0 under the hood..
Mike

 

[Daggar]

The 174 is not intercooled (although I've seen pictures of a couple of custom jobs here and there). For 8 lbs of boost you will not need a intercooler. Keep in mind that blower sits directly ontop of your motor attatched to either the carb or in my case the intake. There's no real plumbing for you to place an intercooler inline. The aftercooler setups I've seen looked like custom spacers designed to fit between the blower and the intake or carb with a small "radiator" in them to cool the air as it went by the fins or were pieces designed for boat applications and adapted for cars (plenty of cool water lying around in a boat application to cool it). For racing applications where the water going through this thing is 20* below ambient temperature or more, they do a great job. For a street car... it's a waste of time and energy. You're causing an air restriction for a discharged air cooling system that is heat saturated (the best you can hope for is that the water in the aftercooler system is kept at ambient air temp... which ain't gonna happen). In that case you've really not gained anything. Your best bet would be to ensure that the air going to the SC is as cool as possible (cold air kit of some sort) and press on. A hood scoop would look awesome. Once again... keep in mind that air charge temp on a twinscrew blower is considerably cooler than that of a cnetrifigul. For your application I can't see how an inter or aftercooler would help you.

 

[94TURBO5 O]

Take a look at my sig. I have no new #'s since adding a O4 PMS and SP boost cooler. I run a solid 12 #'s and have no problems over the last year after the blower install. I would guess I'm over 425 now at least with the new mods and my car is beaten on daily.
IMO don't worry about anything until it breaks and then replace it with something stronger.