Just built a 383 9.7 comp. GM Hotcam, Holley street Dominator intake, heads are 193 casting pocket ported and are not swirl heads, I have a set of 041's I am working on for this engine, Holley 730cfm carb(I know that is a funny size, it was a factory Holley) 700R4 rebuilt with all updates and heavy duty parts plus shift kit. I only have 2.73 gears with limited slip, but plan on changing to 3.55 or 3.73 later. The car weighs about 3350 with me in it and I will be using slicks, traction should be no problem. Take an educated guess if you would, the track doesn't open again until Feb. Thank you!!

 

How much torque converter? Any suspension work? Is the carb a double pumper? What size are the tires?

If you want a guess without knowing everything about the vehicle, I'll say low 14's and maybe high 13's if it can hook up.

I'm only estimating 240-250 rear wheel hp.

 

The motor will only put out about 300hp, pushing the car into the high 13's if you are lucky.

Those heads you are gonna use will choke every bit of power potential the motor has right out of it. Even ported 041's are gonna kill the power. What you need are a good set of aftermarker heads (gonna be aluminum) to get big power. Just throwing on a set of Edelbrocks will probably give another 75hp. If you go AFR or Brodix, at least 100hp. Heads are the key.

As for the Holley, sell it to some old schooler and get a rebuilt Q-Jet or a new Edelbrock (your preference). They are a million times easier to tune than a Holley and are more streetable.

The trans and gears will be fine (3.42 or 3.73 in a 10 bolt). Do get a big trans cooler too.

Don't forget the exhaust! The second easiest way to choke a motor is an exhaust too small for your power level. A 3" exhaust will choke the hell out of a 450hp motor, possibly bringing it down 75hp or more. You are gonna need a 3-1/2" or 4" one for your car.

Bottom line: if you put it together right and tune the sucker it should make between 400 and 450hp. If you don't get the right parts and tune it, it may hit 300hp.

 

I have a 2000 stall, subframe connectors, and I am going to be running slicks at the track. I don't mean to sound smart, but 300 hp?, you gotta be kidding. If what I am driving now is 300 then the 305 I had must have had about 10hp and the 350 I had about 150hp. I can't really afford any aftermarket heads right now, though I am sure they would make a difference. The dual exhaust and headers is coming in about a week. I appreciate your replies, but don't insult my engine without facts.

 

Weigh the car just as you would be sitting at the starting line. You, fuel, helmet etc. Give us a 1/4 mile mph and I'll tell you exactly how much HP you're putting to the rear wheels. Then we'll decide if it's insulting or not. You wanted a guess so we're giving you a guess.

Too many people think just by swapping a bunch of parts around and using moderate performance parts that they'll get a 400 HP 350. It's not as easy as it looks. A typical 350 only gets 200-230 HP stock. Trying to squeeze another 100 hp only takes a little bit of work. Getting another 100 hp on top of that takes a lot of work.

 

James,

I don't mean to be a ballbreaker, but typically a street 350 with average heads and parts puts out around 300hp. Of course it may have 400lbs of torque that will make it feel fast compared to a 275lb 305. When you rev a 400hp 350 past 5000rpm is where it really starts pulling, not pooping out. Anyway, the only real way to test the hp is to run it at the track or dyno it. While others prefer dyno, it leaves out things like stall speed , gears, and traction problems that only the actual 1/4 mile run can show (all else being equal).

Start saving for some heads and 400hp is yours.

 

Like I say I wasn't trying to be smart and I apologize for the outburst, but I have ridden in a 300 hp 3rd gen and it never felt like this. To make 400 hp out of a 350 is a little harder than most people think, but this is a 383. I don't know for sure about these heads but the owner of a reputable shop told me that they would be close to Vortech when he was finished. I was originally going to use Vortech heads until he said that. This guy isn't an idiot, his main business is building race engines so I believed him, if you think he was wrong let me know and give me some facts you could be right. Heads are probably the only thing I don't have too much knowledge about as I could never afford 2-3 different sets at the same time. I will post 1/4 times and let you guys tell me what I have if the dyno trip doesn't happen this winter. I am guessing by how it quick it gets to 100 and above that it will be in the mid to low 13's. I appreciate your responses even if I did fly off the handle a little.

 

James,

Like I said before, the only true way to get a HP # is to either have it dyno'd or go to the track (more fun).

Since a 383 is about 10% larger than a 350, it will be easier to squeeze 400hp out of it, but even a 350 can do it and still be streetable.

Vortech heads are probably the best affordable small volume head chevy ever produced, flowing enough air for a 425hp motor. Can your guy port those heads to that level? Who knows. But for the $425 a pair cost for the Vortechs, he better be cheap porting or you could have bought the Vortechs to begin with. FYI: except for some hard-core racers, no body has more than one extra set of heads floating around, costs too much to have as bookends.

 

Yea, he charged me 150 dollars to port them and like you say who knows Vortechs may still be better. Two reasons I didn't use them were underhood concerns and what the machinist said. He actually told me that for low (my carb stud hits the hood right now) end these would be fine, only bigger valves would make them better, but for high end horse aftermarket would be better. I built this engine to drive every day to work (100 miles roundtrip), make lots of low end torque , play at the track occasionally, never see 6000 r.p.m. and last 100,000 miles or more. So far I am very pleased with it. I am going to race a 12 second T.A. this weekend and we'll see how far behind I am. Once again thank you for your input it is appreciated.

 

Those heads with the right combo will get you in the 12's.

You only need like 180 cfm out of the heads to hit decent power to hit high 12's. If you gear and get the right convertor, you will hit low 13's easy.

 

There are a few really good articles in the new Car Craft about factory cast iron heads and power potential. It gives max power potential out of the box for Vortech heads and bow tie heads, the Vortech heads win out of the box, but the Bowties have more racing potential after porting. They also show how they gained 60 hp from porting some junk smog heads. I think porting out the 041 castings completely and correctly could really increase power for almost no cost to me. My cousin, who has had 3 low 12 second cars and one that ran 11.60 at 120 rode last night and told me I was already in the high 13's and the car isn't even fully tuned. He had a 93 that ran 13.9's factory and we both thought my car would roast it. Well anyway its only 2 months away from the track opening and this debate will be decided. Thanks for the replies.