I have a 69 vette and I want to do some work on the engine to get it over 400HP, I think the motor is a 350 and I am not sure what I need to do to get it over 400, 450HP would be nice. What would it cost and where can I read about different mods? thanks

 

How much do you know about cars? If you ware wanting to do it yourself and don't know much I recommend you start by reading the book, "How to Build a Small Block Chevy" OR, if you want a nice simple cheap way go get yourself a nice GM crate engine and just drop it in.

 

First, several points, to put this in perspective. First, 350-cubic inch Corvettes in that period came from the factory in one of several differen available ratings depending on cam, compression, carb, etc., rated at somewhere around 300 to 350 HP. This was during the period when the auto industry used SAE gross ratings, whereas today they use net ratings: those 1969 engines corresponded to a an equivalent HP rating of about 240-275 HP in modern terms (the industry switching to net ratings in '73, which rated the same engine at about 20% less power - 300 HP became about 240 but was still the same engine - just measured more conservatively). Furthermore, net rating is at the engine flywheel: these cars, as new and in perfect condition, probably put down about 200-240 at the rear wheels. Still, that is pretty good-- my new Porsche 996 (320 HP net flywheel rating) put down only 265 at the rear wheels (RWHP).

Second, all of GMs standard offerings, 350 and 427 cubic inch in 1969, were carburated. I believe, there had been a 375 HP fuel injected 327 or 350 available prior to the big block (427/454 cubic inch) engine being offered starting in '66, but that was dropped once the bigger engines were offered.

Third, about your 400-450 HP target. If you are talking about 400-450 g r o s s HP (ie., as they rated them back in '69), that is very doable without too much hassle: that is about the equivalent of 320-340 net Hp (as cars are rated by manufacturers today) and would give somewhere around 285-300 Hp at the rear wheels.
If you are talking 400-450 n e t HP (i.e., as they rate cars today), which would correspond to about 350-385 rear wheel HP, that also is doable but willb e a stetch
If you are talking 400-450 RWHP, that is equivalent to the new 2006 Crovett3e ZO6, which is running a fuel injected, dry sump 7-liter (427 cubic inch) engine rated at 505 net HP, and that is barely doable but will cost a lot.

Talling about extreme first. You cannot get 400-450 RWHP in this car without spending A LOT. You will have to use a modern, fuel injected, ditigally controlled engine, (LS-1, -2, or -6) with major modifications, or a rather standard LS-7 crate engine (the dry sump, 427 cubic inch engine in the new 2006 ZO6 Corvette: there isn't much to chose in terms of new cost or performance between the two. I believe there are kits or available fabrication parts to fit this modern engine in a 68-72 vette, but it can be done. I would guess total cost by the time you buy the engine, get it in the car, put on an exhaust, etc., figure out what to do with the transmission (I'd use a modern trans, too), etc., to be around $15,000 - I certainly wouldn't go into it unless I knew I could spend up to #$20k. Your car would be very driveable on the street, unique and a big hit at car shows, and have immesne power - but you'd have problems with the rear end and suspension breaking from the power and the brakes would be barely adequate (assuming you were prudent with the power- if you weren't prudent you'd wreck the car and maybe kill yourself).

At the other end, you can buy gobs and gobs of parts to hot rod the 350 chevy small block and can have a fun hobby, spending anywhere from a couple of grand to pick up 50 Hp, to much more to pickup much more, a step at a time at the pace you want, and in the manner and style you want. There is a world of choice and its up to you. Buy several books, Lingenfelter's and some others, and read up. Buy and read Hot Rod magazine for a few months, and/or GM High Persformacen magainze. Visit web sites of manufacturers like Crower and Lunati, and edlebrooke, etc., There is a world of unlimited choices in what, where, and how you start, and how far you go . . . that said, you will have a lot of fun, and learn alot (and suffer some disappointment and frustration), but I doubt you will get 400-450 net Hp out of a 1969 350, carburated, unless you turn it into a drag special -- something almost undriveable in day to day traffic, etc.

But in the middle, is what I would recommend. Buy and have a good shop install a General Motors ZZ383 crate engine. This is a complete, ready to go, "hot rodded" engine, built by General Motors, guarranteed to General Motors, based on a more modern derivative or your original 350, with everything you need, in a crate- open it up, drop the engine in, connect it to fueul and electrics, and start the car (oklay its not quite that simple, but not far off). The ZZ383 has been stroked from 350 to 383 cubic inches (10% bigger) and modified to produce much more power (about 510 by the gross rating system of 1969). It costs about $5000 complete at the prices you can find on the internet. It is rated at 425 HP (net engine rating) , and once in the car would put down about 350-350 at the rear wheels. It would fit without much fuss (its basically a very smartly hot-rodded version of what you car came with from the factory), it would fit your existing trans without much modifcation, etc but would prbably require new headers and a new exhaust system. If I were doing it with my local shop, I'd allow a cost of about $8K for the engine and the cost of labor and all the little things you run into along the way, but I'd also replace the trans with a new stock verison of the original (it now has to deal with ALOT more power) and I't have the rear end and suspension rebuilt (same reason) so I'd count on spending about $11k. You would have a well balanced 1969 Corvette with more power than any '69 vette, even the pure race ones, had at the time. The engine would have a gaurrantee, it would be very driveable or the street.

 

Thank you Lee Willis, you answered many questions that I have been thinking about. After reading what you posted I have come to a conclusion that I will eventually drop in a new engine and possibly the ZO6 engine and trany, however I will have to save up for it and will probbably wait till the engine in there now gives out! But after installing that in a 69 stingray I would have an extremely valuable car right? I paid 11,000 for my vette and I think after spending 15-20,000 improving the motor and trany and suspension and other variables I would retain that money in resale value.


several more Q's
You cant supercharge a carburated motor can you? One other thing I dont understand is the difference between net HP and HP at the wheells. Gross HP is measured just engine right, without transmition? what is the 2006 ZO6 HP at the wheels?

Thanks again Willis for the great post!

I like the idea of having a 1969 ZO6 with all the power and the old car look. Do you know of anyone that has done this conversion with a shark? You said you think there are some kits for this kind of conversion. Is this idea even possible, like will it fit in the shark?

 

MY ANSWERS BELOW IN CAPS.

Thank you Lee Willis, you answered many questions that I have been thinking about.

yOU ARE CERTAINLY WELCOME. yOU HAVE A NICE PROJECT IN MIND.

After reading what you posted I have come to a conclusion that I will eventually drop in a new engine and possibly the ZO6 engine and trany, however I will have to save up for it and will probbably wait till the engine in there now gives out! But after installing that in a 69 stingray I would have an extremely valuable car right? I paid 11,000 for my vette and I think after spending 15-20,000 improving the motor and trany and suspension and other variables I would retain that money in resale value.

I WOULD NOT COUNT ON IT ONE WAY OR ANOTHER. IT IS NOT EASY TO FIND A BUYER FOR A HEAVILY MODDED CAR, EVEN IF DONE VERY WELL, UNLESS YOU ARE A BIG NAME SHOP, ETC. MOST ENTHUSAISTS WANT THE FUN OF DOING THE PROJECT THEMSELVES.
bUT YOU WOULD HAVE A UNIQUE CAR AND SOMETHING PEOPLE WOULD ADMIRE, AND YOU MIGHT FIND SOMEONE TO PAY YOU WHAT YOU HAVE IN IT, BUT I WOULD NOT ASSUME THAT YOU CAN GET YOUR MONEY OUT, OR THAT YOU COULD SELL IT QUICKLY, EITHER. A CASE IN POIN IS MY VETTE. I HAVE OVER $100K IN IT AND IT IS TRULY IMPRESSIVE; LOOKS "LIKE A CORVETTE FROM HEAVEN' AS ONE PERSON TOLD ME, AND IS FASTER THAN JUST ABOUT ANYTHING ON THE STREET. BUT COULD I SELL IT FOR WHAT I HAVE IN IT? NOT EVEN CLOSE. I COULD PROBABLY GET ABOUT $45-55 FOR IT.


several more Q's
You cant supercharge a carburated motor can you? YES, YOU CAN, ALTHOUGH MY OWN PREFERENCE IS NOT TO. YOU ESSENTIALLY PUT THE ENTIRE CARBURATOR IN A SEALED BOX THAT THE sc PRESSURIZES. IT CAN WORK. BUT ITS COMPLICATED AND GETTING THE JETS/THROTTLE CAMS/ETC. OF A CARB ALIGNED WITH A SUPERCHARGER CAN BE A NIGHTMARE FUEL INJECTION WITH COMPUTERS HAS A COMPUTER PROGRAM TO ADJUST ALL THAT, USUALLY A SMART ONE, TO DO MUCH OF THAT FOR YOU.


One other thing I dont understand is the difference between net HP and HP at the wheells. Gross HP is measured just engine right, without transmition? what is the 2006 ZO6 HP at the wheels?
tHIS IS COMPLEX:
GROSS HP: UP THROUGH 1972, CAR MANUFACTURERS USED A GROSS RATING SYSTEM, WHICH YOU CAN THINK OF AS THE MAXIMUM hP YOU COULD EVER COAX OUT OF THE ENGINE WHEN IT WAS OUT OF THE CAR, WAS NOT RUNNING ANY ACCESSORIES, EVEN ITS WATER PUMP, HAD NO MUFFLERS ON IT, NO AIR CLEANER, ETC.,

NET HP: IN 1973, AND CONTINUING TODAY, NET RATING REFERS TO TESTING THE MOTOR OUT OF THE CAR, BUT WITH ALL THE ACCESORRIES LIKE WATER PUMP, ALTERNATOR, RADIATOR FAN, AC COMPRESSOR (THE AC IS TURNED OFF BUT THE MOTOR HAS TO SPIN THE IDLE PULLEY, AIR CLEANER AND STOCK AIR INTAKE, EXHAUST MANIFOLDS, CATALYTIC CONVERTERS, EXHAUST PIPES AND MUFFLERS FROM THE CAR. THIS REDUCES THE GROSS HP TO THE NET HP THE ENGINE PRODUCES.

REAR-WHEEL HP: BUT ONCE IT IS IN YOU CAR, THE POWER THE ENGINE PRODUCES HAS TO DRIVE THE TRANSMISSION, THE U-JOINTS AND THE DRIVE SHAFT, THE DIFFERENTIAL AND THE TIRES, ALL OF WHICH HAVE SOME FRICTIONAL LOSSES (FEEL THE TRANMSSION SOMETIME AFTER A LONG DRIVE, ITS ALMOST 200 DEGREES, THAT TEMPERATURE CAME FROM GEAR FRICTION - ENERGY REQUIRED -- INSIDE THE TRANS). ALL TOLD, A CAR WITH A GOOD TRANS AND DIFFERENTIAL WILL "USE UP" ABOUT 11-15% OF THE NET HP FROM THE ENGINE FLYWHEEL ON ITS WAY THROUGH ALL THAT DRIVETRAIN TO THE REAR TIRES.
THUS, WHAT YOU MEASURE WHEN YOU PUT THE CAR ON A CHASSIS DYNOMETER LIKE A DYNOJET OR MUSTANG DYNOS (MUSTANG HERE HAS NOTHING TO DO WITH MUSTANG CAR, IS A BRAND OF DYNOS AND METERS) IS THE HORSEPOWER THAT ACTUALLY GETS FROM THE MOTOR (WHATEVER IT ACTUALLY PRODUCES, NET) THROUGH THE TRANS, DIFFERENTIAL, TIRES, ETC, AND OUT TO THE REAR WHEELS. THAT'S ALL YOU REALLY CARE ABOUT BECAUSE THAT'S WHAT MAKES THE CAR GO FAST.

EXAMPLE: ONE MODEL 1972 CORVETTE AHD A 454 V8 RATED 400 HP BY GM, UNDER THE GROSS RATING SYSTEM.
THIS WOULD HAVE BEEN ABOUT 325 HP UNDER THE NET RATING SYSTEM USED AFTER 1973
AND THE CAR PUTS DOWN ABOUT 280 RWHP ON A DYNJET

Thanks again Willis for the great post!

I like the idea of having a 1969 ZO6 with all the power and the old car look. Do you know of anyone that has done this conversion with a shark? You said you think there are some kits for this kind of conversion. Is this idea even possible, like will it fit in the shark?
I SAW AN ARTICLE IN HOT ROD, OR CORVETTE MAGAZINE OR SOMETHING WITHIN THE LAST YEAR ON SOMEONE WHO HAD PUT AN LS1 WITH A MAGNUSEN SUPERCHARGER, ABOUT 500+ HP, IN A CORVETTE CHROME BUMPER C3 - NOT SURE WHICH YEAR BYUT SOMEWHERE IN THE 68-73 TIMEFRAME. IT WAS CLEAN AND NICE. ONLY CASE I KNOW.

 

In all likelyhood your car will never be more valuable than it would be with the original drivetrain. Mods are very personal and will never bring anything on resale close to what they cost you. If you want to spend the money to have a fast ride and look cool great but you will be paying for it. Don't expect someone to pay what you paid for what you want.

 

Thanks guys,

As far as resale, I dont think I would sell the car after doing all that work but I just thought doing that work would make resale value skyrocket but if there is no market for sharks that are built to that level then thats even more incentive to keep the car for life after a rebuild of that magnatude.

Thanks for explaining the HP rating differences.

I saw a 69 vette rebuilt with a ZL1 and several other sharks rebuilt with various big blocks but none with more modern engines such as the LS7 or LS6, saw these in a magazine, anyway I look forward to someday heavilly moding my 69 and I want to keep it looking stock and maybe with a tiny LS7 logo somewhere on the hood. I need to go buy some loto tickets thanks again

Brandon.