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Solid axle conversion kit recommendations, I need some
I'm going to do a solid axle conversion on my '69 and I need some recommendations on what conversion kit to get. I was looking at the one from Autofab but then I read on their website that it's only capable of handling up to 800 horsepower, the engine in my car was built to make a whole lot more than that. It's an 8-71 supercharged 454 built to handle making up to 1500 horsepower (4 bolt block, Eagle's top of the line crank and rods rated to handle 1500 hp, speed pro forged blower pistons, lunati roller valvetrain, big port heads, etc). I can more than likely get it to that power level by overdriving the blower a bunch but if I do that everything from the flywheel back will turn into confetti when I hit the gas. I've got the blower under driven a bunch right now to keep the power down enough to not blow the trans (stock turbo 400) and blow the stock IRS diff. The driveline plans are for a built 4L80E, a super duty driveshaft and u-joints, a 4 link/coil over setup, and a built 9 inch Ford diff with disc brakes. By the way, I do all of my own work, I will be doing whatever mods and welding work are needed to complete the task. I do not want to cut and narrow the frame and cut out big pieces of the rear flooring for giant wheel tubs because it's not going to be a drag race only car, most of it's driving is on the street (the engine has great street manners: smooth idle, doesn't run hot, etc). I want the abilitity to be able to bring the car back to stock original factory condition if I ever get the desire to do that someday in the future. It's a resto mod for lack of a better way to put it, the interior has been restored to factory original condition, it has stock 8 inch rally wheels, and factory sidepipes (I know, the factory pipes are killing a LOT of horsepower buts that's actually a good thing right now because I don't want it making enough power to break the drivetrain). Other than the giant blower sticking up out of the hood it looks like a nice original '69. I don't care if the slicks stick out of the wheel wells at the strip, the amount of time it will spend there will be nothing compared to the amount of time it will spend on the street. Anyway, I'm sorry this post ran a bit long, I just wanted to give everybody an idea of what I have and what my goals for it are to avoid a bunch of questions later. Any help is appreciated.
By the way, here's a pic of the car in case anyone wants to see it:
Last edited by TheGreek!; Nov 6, 2021 at 12:31 AM.
I wouldn't worry about it not holding the power. The brackets and links are same as everyone uses. You'll just have to determine what diff and axles you'll use...that's the place wear strength will be determined.
Have you ever dyno'd it? Can you share more of the engine combo? Cam, headwork, compression etc?
I'm building a 6-71 blown 408" Clevor engine for a Ford project I'm building. Plus my Vette is a twin turbo 555" street car...so I love boost!!
Since you do your own work, you might want to consider building your own version of the Autofab like kit, and increasing the strength in some places. I went that route and chose larger diameter 4 link components as well as some extra frame reinforcing, in my build,. Like you, mine is an occasional strip car, so I also went with the 4L80E.
My personal opinion is that at some power limit, it's hard to have a dual purpose car. If you go over roughly 800 HP, you're going to need an 10 point cage at a minimum, and frame reinforcement, fire suppression and so on. In my case, I drew the line at a 5 point cage which allows me to go 10.0 and still be able to get in and out of the car for fun cruising and not twist the frame into a pretzel.
It can be done. 1500HP could put you in the 7's and 175 MPH. Be careful what you wish for.
Sounds like more of a show car to toy with on the street rather than a drag car. If you are really gonna make that kinda power and expect it to work at the track you need some real frame and suspensions mods, I’d look at just back halving the car if you really wanted it to work however from your description it sounds like you want a number to hit on the Dino and a street cruiser. It’s hard to have both with setups like this, twin turno Ls cars make this power no problem with good street manners but it’s a bit different going the direction you are. Honestly I think you would be fine with an Autofab kit maybe some upgrades to it if you were truly gonna make the car work at the track, for street driving with some street hits I think you would be fine.
I wouldn't worry about it not holding the power. The brackets and links are same as everyone uses. You'll just have to determine what diff and axles you'll use...that's the place wear strength will be determined.
Have you ever dyno'd it? Can you share more of the engine combo? Cam, headwork, compression etc?
I'm building a 6-71 blown 408" Clevor engine for a Ford project I'm building. Plus my Vette is a twin turbo 555" street car...so I love boost!!
JIM
I haven't dyno'd it yet, I'm not concerned about what power it's making at the moment as long as it stays low enough to not turn everything south of the flywheel into confetti, lol. There's still a few things I want to do to it yet before I dyno it, I want to get aluminum heads to make even more power but mainly to take some of the extra weight the blower added to the front end off (I weighed the blower assembly with the carbs and intake and it weighs 160 pounds!). I also want to replace the factory sidepipe mufflers that are killing at least 100 horsepower on it with something that flows a lot better and fits under the factory sidepipe covers. As for more engine specs, its a .030 over gen 6 one piece rear main seal 454 four bolt main block that has the rare mechanical fuel pump boss on it, Eagle's top of the line non twist forging crank with the standard 4 inch 454 stroke (I ordered it with all the available options that bring it's power capability rating to 1500 HP) and I also ordered the "blower cut" to be done on it. The blower cut is an extra harmonic balancer key cut on the nose of the crank to be used with "blower balancers", harmonic balancers that have two keys instead of only one to prevent it from shearing off the key under high boost which can happen when there is only one key in the balancer. The rods are Eagle's top of the line H-beam rods (standard center-to-center length) with the strongest optional rod bolts they offer, they're also rated for up to 1500 horsepower. The pistons are flat top Speed Pro forged blower pistons w/floating pins. The compression worked out to around 7.6 to 1 before the block was zero decked, now it's around 8 to 1 after the zero decking job. The cam is a Lunati hydraulic roller w/lunati lifters but I forgot the specs on it and can't find the damn spec card that came with it. I think the lift is in the upper .500's but I can't remember the duration and overlap. I do know that it isn't a lumpy race cam because rather than destroy it's streetability with a super lumpy all out race cam I figured I could always just add a little more boost to make up for it. I wanted incredible horsepower AND nice street manners which is hard to do on a normally aspirated engine but not very hard to do on a supercharged engine. The pushrods are 3/8 chrome moly, and the valve springs are Crane dual springs w/damper and with 10° steel retainers and locks. The heads are big port open chamber that were removed from a brand new 502 with 0 miles, I didn't do anything to them other than replace the springs, retainers, and keepers. They are going to be replaced later with a set of aluminum heads but I haven't decided which ones to go with yet. The rocker arms are Elgin stainless steel roller rockers. The chain is a roller chain, a Cloyes Tru-roller if I recall correctly. The balancer is a special "blower balancer" that has the blower cut but once again I can't remember who made it. It came from eBay if that helps, lol. The water pump and pulley is aluminum. The induction system consists of a Weiand 8-71 blower underdriven 11%, the Weiand intake that comes with the blower kit, and it has two Holley HP 850 double pumper carbs that I modified by boost referencing the primary power valves and replaced the secondary power valves with block off plugs and then jetted the secondaries six steps richer to compensate for it. Ignition is MSD with an externally mounted coil because distributors with internally mounted coils are too big to fit behind that big 8-71 blower. All of the machine work (boring, balancing, etc) was done by Larry's Engine and Marine out here in Tucson where I live. They do great work. I did the engine assembly and installation work in my garage making sure to check every bearing clearance, every piston ring end gap, every piston to wall clearance, crank end play, etc, etc. It fired right up on it's first start and has run perfectly ever since. I don't know what it runs at the track but I did recently race a new ZL1 Camaro from about 30mph up to well over 100, by the time we backed off I beat him by a few lengths if that gives you an idea of how it currently performs with low boost.
Last edited by TheGreek!; Nov 7, 2021 at 07:40 PM.
Since you do your own work, you might want to consider building your own version of the Autofab like kit, and increasing the strength in some places. I went that route and chose larger diameter 4 link components as well as some extra frame reinforcing, in my build,. Like you, mine is an occasional strip car, so I also went with the 4L80E.
My personal opinion is that at some power limit, it's hard to have a dual purpose car. If you go over roughly 800 HP, you're going to need an 10 point cage at a minimum, and frame reinforcement, fire suppression and so on. In my case, I drew the line at a 5 point cage which allows me to go 10.0 and still be able to get in and out of the car for fun cruising and not twist the frame into a pretzel.
It can be done. 1500HP could put you in the 7's and 175 MPH. Be careful what you wish for.
Can you give me some info/pics of the larger 4 link components you installed and also some info/pics of the frame reinforcing you did? By the way, even though I built the engine to be able to reliably handle making up to 1500 horsepower I'm not going to crank it all the way up to that power level. I'd like to see at least a thousand horsepower out of it which shouldn't be all that hard with some more boost but I don't want the power to be at ragged edge of blowing the engine.
Last edited by TheGreek!; Nov 7, 2021 at 07:36 PM.
I haven't dyno'd it yet, I'm not concerned about what power it's making at the moment as long as it stays low enough to not turn everything south of the flywheel into confetti, lol. There's still a few things I want to do to it yet before I dyno it, I want to get aluminum heads to make even more power but mainly to take some of the extra weight the blower added to the front end off (I weighed the blower assembly with the carbs and intake and it weighs 160 pounds!). I also want to replace the factory sidepipe mufflers that are killing at least 100 horsepower on it with something that flows a lot better and fits under the factory sidepipe covers. As for more engine specs, its a .030 over gen 6 one piece rear main seal 454 four bolt main block that has the rare mechanical fuel pump boss on it, Eagle's top of the line non twist forging crank with the standard 4 inch 454 stroke (I ordered it with all the available options that bring it's power capability rating to 1500 HP) and I also ordered the "blower cut" to be done on it. The blower cut is an extra harmonic balancer key cut on the nose of the crank to be used with "blower balancers", harmonic balancers that have two keys instead of only one to prevent it from shearing off the key under high boost which can happen when there is only one key in the balancer. The rods are Eagle's top of the line H-beam rods (standard center-to-center length) with the strongest optional rod bolts they offer, they're also rated for up to 1500 horsepower. The pistons are flat top Speed Pro forged blower pistons w/floating pins. The compression worked out to around 7.6 to 1 before the block was zero decked, now it's around 8 to 1 after the zero decking job. The cam is a Lunati hydraulic roller w/lunati lifters but I forgot the specs on it and can't find the damn spec card that came with it. I think the lift is in the upper .500's but I can't remember the duration and overlap. I do know that it isn't a lumpy race cam because rather than destroy it's streetability with a super lumpy all out race cam I figured I could always just add a little more boost to make up for it. I wanted incredible horsepower AND nice street manners which is hard to do on a normally aspirated engine but not very hard to do on a supercharged engine. The pushrods are 3/8 chrome moly, and the valve springs are Crane dual springs w/damper and with 10° steel retainers and locks. The heads are big port open chamber that were removed from a brand new 502 with 0 miles, I didn't do anything to them other than replace the springs, retainers, and keepers. They are going to be replaced later with a set of aluminum heads but I haven't decided which ones to go with yet. The rocker arms are Elgin stainless steel roller rockers. The chain is a roller chain, a Cloyes Tru-roller if I recall correctly. The balancer is a special "blower balancer" that has the blower cut but once again I can't remember who made it. It came from eBay if that helps, lol. The water pump and pulley is aluminum. The induction system consists of a Weiand 8-71 blower underdriven 11%, the Weiand intake that comes with the blower kit, and it has two Holley HP 850 double pumper carbs that I modified by boost referencing the primary power valves and replaced the secondary power valves with block off plugs and then jetted the secondaries six steps richer to compensate for it. Ignition is MSD with an externally mounted coil because distributors with internally mounted coils are too big to fit behind that big 8-71 blower. All of the machine work (boring, balancing, etc) was done by Larry's Engine and Marine out here in Tucson where I live. They do great work. I did the engine assembly and installation work in my garage making sure to check every bearing clearance, every piston ring end gap, every piston to wall clearance, crank end play, etc, etc. It fired right up on it's first start and has run perfectly ever since. I don't know what it runs at the track but I did recently race a new ZL1 Camaro from about 30mph up to well over 100, by the time we backed off I beat him by a few lengths if that gives you an idea of how it currently performs with low boost.
Fun combo for sure. It's going to take some work to make 1500+ with a roots combo on gasoline. I love 'em...but they can be tough to make the big power without some serious parts. I'm building a 408" Ford for a project of mine mainly because they look and sound real cool. Similar to you...all real nice forged parts with upgraded rod bolts, custom pistons with gas ports and thin steel rings, added keyway on crank, ported aluminum heads, solid cam etc etc. Not sure what it will make for power yet..but it's gonna be fun!
My car has a couple of small turbos on a 555" with really nice heads etc. They are way too small for that many cubes...but make near instant boost which is fun on the street. They make around 17 psi boost. Makes 1240 RWHP and runs high 8's@162 MPH so far. IRS and a stick trans. Can drive anywhere...and it ran 200 MPH at the TX Mile.
Ck out this 540. It took 35% overdrive to make 11 Psi and 939HP with a solid roller (relatively small) and aluminum heads.
Can you give me some info/pics of the larger 4 link components you installed and also some info/pics of the frame reinforcing you did?
I believe I use larger diameter heim joint components for starters. I don't have the spreadsheet with the details with me right now, but I believe the diameters were 3/4 and 5/8. Not positive, it was a while ago. The 4 link tubes are a thick wall chromolly.
The 4 link housing brackets support I used is for 3 1/4" axle tubes. I think the kits are 3". At your power level, you may want to consider not cutting of the wheelie bar mounts like I did and install a set.
The cover welded over the hole where the swing arm used to go has reinforcements that go through the chassis and are welded the the other side of the chassis to provide more strength.
Those reinforcements were welded at the yellow arrows.
The chassis bracket I chose extends below the bottom of the chassis which enables some additional reinforcement of the two right angle chassis joints. This extra support is welded at an angle to reinforce the two right angle frame connections.
I was also able to provide additional clearance to allow for a wider tire.
Fun combo for sure. It's going to take some work to make 1500+ with a roots combo on gasoline. I love 'em...but they can be tough to make the big power without some serious parts. I'm building a 408" Ford for a project of mine mainly because they look and sound real cool. Similar to you...all real nice forged parts with upgraded rod bolts, custom pistons with gas ports and thin steel rings, added keyway on crank, ported aluminum heads, solid cam etc etc. Not sure what it will make for power yet..but it's gonna be fun!
My car has a couple of small turbos on a 555" with really nice heads etc. They are way too small for that many cubes...but make near instant boost which is fun on the street. They make around 17 psi boost. Makes 1240 RWHP and runs high 8's@162 MPH so far. IRS and a stick trans. Can drive anywhere...and it ran 200 MPH at the TX Mile.
Ck out this 540. It took 35% overdrive to make 11 Psi and 939HP with a solid roller (relatively small) and aluminum heads.
I looked at the links to the 540 and 496 big blocks and couldn't help but notice that the 496 made damn near the exact same power as the 540 and did it with 4 pounds less boost (7 psi vs 11 psi). Either something is very wrong with the 540 or very right with the 496. The reason why the 540's blower needed to be overdriven so much is because the bigger the engine gets the faster the blower needs to spin to make the same PSI that it would on a smaller engine at the same RPM. As the engine size gets bigger it reaches a point to where you need to get a bigger blower for it too. My engine is only 460 cubes (.030 over 454), the blower shouldn't need to be overdriven much at all to reach the desired amount of boost.
I believe I use larger diameter heim joint components for starters. I don't have the spreadsheet with the details with me right now, but I believe the diameters were 3/4 and 5/8. Not positive, it was a while ago. The 4 link tubes are a thick wall chromolly.
The 4 link housing brackets support I used is for 3 1/4" axle tubes. I think the kits are 3". At your power level, you may want to consider not cutting of the wheelie bar mounts like I did and install a set.
The cover welded over the hole where the swing arm used to go has reinforcements that go through the chassis and are welded the the other side of the chassis to provide more strength.
Those reinforcements were welded at the yellow arrows.
The chassis bracket I chose extends below the bottom of the chassis which enables some additional reinforcement of the two right angle chassis joints. This extra support is welded at an angle to reinforce the two right angle frame connections.
I was also able to provide additional clearance to allow for a wider tire.
Surge tank and battery tray.
Thanks for the pics and info, every bit helps with what I'm going to do with the car.
These cars are exceptional street machines in the 700 Hp area. And if you want 1500 hp take it off the street. And build a straight up race car. Because you will become a danger to yourself and others. I myself have a c/3 4l80e , fab 9 , 4 link bla bla bla and it runs 10.77 on street surfaces with no trans brake at 131 mph. Using a 434 SBC with a hydraulic roller valve train. And a Sequential coil on plug fuel and ignition system.
I hate to be the bearer of bad news but you are not going to clear 800hp with those heads no matter how much boost you put at it.......the exhaust port on the 502 head just will not support it. Also...the Gen 6 block is about done at 1000hp too......
Some kick *** heads and a dedicated boost cam will get you to 1000+ horsepower.......
The good news is that you stuffed the block full of good parts.......especially that double keyed crank......
The other thing is have you driven a 1000hp car......maybe it will be enough for you.
Solid axle conversion kit recommendations, I need some
