Does 720 Hosres sound right ?

I had a guy call me here from Dallas that wants to trade straight up .The guy says he has as much or more in the motor and trans than i have in my whole car .I believe him .What im not sure about is the Horse power he claims it has.Its a .040 over 350 with unported 1.94 heads .It has a lumpy Roller cam and roller rockers.It has 8 to 1 pistons and a 6-71 Weiand blower with two 450 Holleys.He claims it makes 720 Horse power ,it seems a little high to me ,but im no expert on blower motors.It has Msd complete ign ,box ,dist ,wires ,the works and a blower timing retard in the cab.It has a built 400 turbo with a B and M 3500 stall.Its a 1963 short step Chevy truck needs a little finishing up but the motor is just broke in with less than 300 miles ...

 

B.S. Its not pulling that with 450 Holleys!!!

 

If he knows for a fact that it makes 720 hp then he must have a dyno sheet somewher to prove it.

 

I think that it would be closer to 450 with two 750s. been doing this for about 40 years and know small blocks can't get to that level is street form. They need more carbs than that to get the flow needed for the rpm to make horsepower

 

Your buddy might be just a tad full of shit. Blowers really help with the power, but that combination ain't gonna do it.

You CAN get a sb Chevvie with a 6-71 to make 700 horse, but never with those heads and tiny carbs. By way of comparison, I run two 750s on my blown Pontiac and it makes about 650 horse @ 10lbs of boost. Two 450s are way to small for even a mild blown street application.

(Note to D.W. and Kerry: I only run 6lbs at the HAMB Drags....)

-Abone.

 

With an auto trans and the small heads I bet its closer to 350 at the wheels, get a dyno sheet. How much boost is he running? It might be one thing to add up all the hp on paper but tuning it and getting the max hp out of it is another.

 

Carbs sound small, has he ever made passes with it? Should trap 135 - 145mph depending on the race weight.

 

It sounds close. First off I am a machinist I own my own shop and work on this stuff all day. That out of the way... I feel it is possible but I don't know"to many veraibls" The most important thing is the internals, forged crank. h bean rods forged pistons NOT the kb crap. I can build you a motor that will make 750 all day or i can build you a motor that will make 750 twice. If the internals are all forged it might be a good deal but keep in mind a set of heads for these engines are cheap port jobs 800 bucks give or take and enternals run 2 grand or so i have seen stuff for the 350 chevy go for 800 a set. If he has receipts that show all the stuff you need then great, and a dyno sheet is a big plus. dynos only charge 75 or so ask him to take it to one.

 

Dyno sheets generally provide a good reference. (And even then, there are lots of variables.)

You could put all of the engine's parameters into a computer program like Desktop Dyno and get some ballpark numbers.

Dave
http://www.roadsters.com/

 

I thought it sounded a bit too high at 720.The carbs look more like 600's to me in the pics but he said they are 450's...

 

my question is what do you want the motor for what are you putting it in? just curious

 

No way 720 with that set up.I call bull shit .I should be putting out 1440 with my BBC then .My 2 cents

 

I think those are 600's i would need to see closer but I THINK YOU MIGHT BE RIGHT

 

the motor does not look professionally built my 2 cents

 

I'm not sure that motor is puttin out 720...

 

.040 is a odd bore for blower pistons on a 350 its probably a safe bet they are cast. The 1.94s unported on more than likely steel smog type heads not the best choice for any real power, cam.. who knows? Sounds like a low budget "look I'm a bad ass" at the cruise night setup.. Still It could be somthing to work with given the blower and drive unit are decent. Kim Barr and I managed to get at just under 630 on mine on a heavy tune spending almost a full day on the dyno changing jets, then carbs, pulleys, screwing with timing curve on my ancient Mallory, etc. I ended up switching to smaller carbs and taking some initial out of it once I hit the street...

 

I agree with most all of the other fellows here,
been doing this along time and your NOT going to git that kind of power with that set-up.OR with 2x450 carbs..Not enough flow.......

 

Not sure havent decided yet.I wont see it in person till tommorow .I was gunna see if what he said was right or close to being right from the guys here on the Hamb that know blower setups better than i do ,before i got all horny about the trade.I have run into some real Bozo's off my Craiglist ad .I thought his HP estimate was a bit unrealistic but i wasnt sure .He claims he got all the running gear from a guy that abandend a 68 Camaro build he was doing and that the guy spent nearly 12 K on the drivetrain and the motor was setup for a blower from the crank up .He is nearly 60 years old but he sounds like a used car salesman and he acts like if he doesnt get my car hes gunna die.I will have to wait till i see it in person and drive it to tell i guess...

 

I think the horsepower is in the guy's mouth I wouldn't believe anything he says about the internals either.

 

I don't know jack about blower motors and it sounds high to me.

 

I like your car the way it was when it was white, If it were me I'd pass on that...

 

no way its making that kind of hp with those carbs and heads.

 

ask to see the receipts for every dollar spent on it , if he doesn't have them i'm sure the place that did the work could get you a copy

 

well I would say make him dyno it and then look for receipts. if he cant show any then walk. I would say you could build something much better. I built my 4.6 ford for next to nothing it has 500 horse at the wheels and I will be ripping it apart putting new beefier internals and bolting on a set of twins we should be over 1000 all for under 12 grand.

 

how much boost is he making? more boost requires more air. a mild street set up making 5-6 lbs of boost will yield 1.5 hp per cubic inch putting a 350 at around 525 hp. 2.0 hp per cube(700 hp) is obtainable with more boost. it's hard to tell from the pic, but the top pulley does look kind of small. you say he has the option of pulling timing out of it. maybe he is making a ton of boost.

 

I think your right about passing on it.The guy is awfull anxious to get me to trade and he went on and on about how he would never fuck a fellow hotrodder .That threw up a red flag when he said that .Im gunna pass i think ...

 

keep hunting...you will find something better!

 

Thanks for your help guys ,im gunna keep looking.Im in no hurry to get rid of what i have...

 

IMHO......Could be around 400 ta 450 hp....
And I think thats pushing it.......
.No more with out better flow..

 

What is it that you want/are to trade with this other guy,
That he can't live without?