How much power for a stock '69 Mustang?

Hey guys,

I'm planning some extra power (wanted 600-700hp) for my '69 Mustang.
The question is how much power can a almost stock (new restorated and all new parts) Mustang chassis handle? I have ssbc power brakes, discs in the front, stock C6 with 2400 stall converter, 9" rear end but that's pretty much it.
So how far do you think I can go with my future 521cui engine? When will the chassis bend too much or whatever?

Thanks a lot in advance for your answers
Franz

No problem with mine at 730hp. I do have subframe connectors,10pt cage and ladder bars. It was not a rare car or anything and some of the original frame and floor pan was gone......So I do what I want to with and don't give a shit. No problems at all so far besides hating the shock towers. They will be gone soon.

Be sure to stiffen that thing some. A friend with a 514 Mach 1 (stock chassis, no cage) has noticed some minor "reshaping" of sheetmetal.

Since it's a uni-body, (and will most likely see decent torque numbers) at the very least it's probably going to need weld-in (through the floor) subframe connectors to tie the floor & front/rear frame sections all together. If it's not going to be getting a roll bar/cage assembly then the sf connectors probably should be made of 2x3 tubing vs 2x2 tubing or round tubing.

If it's also getting a simple NHRA/IHRA legal roll bar, (that will be tied to the sf connectors at the main hoop) then downsizing to 2x2 tubing for the weld-in sf connectors (vs the 2x3 tubing) is usually OK strength wise. But using the 2x3 tubing instead of the 2x2 is also OK too if you don't mind the added weight.

Add a NHRA/IHRA full roll cage (again tied to the sf connectors) vs just a simple roll bar and weld-in sf connectors made out of round tubing would be OK strenght wise. But as before you could also use 2x2 or 2x3 instead of round tubing (if you want to) if you didn't care about the added weight.

As for the rear suspension, at the very least it's going to need some sort of traction device to avoid damaging wheel-hop/leafsrping wrap-up from happening under load. The easiest setup would be just a simple set of bolt-on slapper bars....as long as they aren't some of the super short and/or dirt-cheap crap that's out there made of real thin material. It's best if they are at least long enough that the rubber snubber hits under the front leafspring bolt. Shorter than that and it's possible to end up bending the leafsprings (and the shorter the bar, the more violent it's action will be).

Beyond simple slapper bars the aftermarket also offers the Caltrack bar, ladder bar in both street use and strip designs, 4-bar/4-link (again in both street use & strip designs). There are also some aftermarket setups that copy/mimic the suspension design that the Shelby Mustangs used to have. The Shelby bar looks somewhat like the Caltrack bar, but it's front attachment point is the frame (the Caltrack bar front attaches to both the leafspring and leafspring mount). But I would not use a "race" design ladder bar/4-link setup without some sort of a roll bar/cage installed in the car.

IMO an all stock 1969 mustang can barley handle a 428 CJ....... So a 700hp BBF is going to be way to much IMO

For a stocker type driver I'd set my sites a little lower, like 450-475hp with the exception to that if you wish to do some modifications like dave has outlined above.

thanks a lot for your answers! And thank you Dave for showing up what you would recommend for my build.
What do you think of following parts, will they be enough to handle the power?

https://www.mustangsunlimited.com/itemdy01.asp?T1=SFC1+01&Category=Suspension+%26+Steering&subCategory=Sub+Frame+Connectors&CatKey=EMUSTANG
and
https://www.mustangsunlimited.com/itemdy01.asp?T1=C2109+01&Category=Suspension+%26+Steering&subCategory=Traction+Bars&CatKey=EMUSTANG

It´s mustangsunlimited because I´m ordering with them for the most part. Summit does not really have good products for this application (I usually love to shop there)
If you have better sources just let me know.


Thanks again guys

I'd suggest you get a complete suspension system from these guys. That would include springs, Bars and shocks.

http://calvertracing.com/

The Connector package you linked, looks like a nice part.

I'd also very seriously consider putting a 6-8 Point cage in the car too.

ok, so I will have to get one of those subframe connectors as mentioned above. But I can not touch the interior. If the power I´m looking for is not working without a cage inside the car, I will have to lower the power.. but as you can imagine I do not like that
thanks a lot for your help! If you have any more ideas or tips, just let me know

Sounds like you need 2 cars. One street and one race.

Maybe I should try some lotteries
What do you think how much power the chassis can handle with the full subframe connectors and traction bars?

I had a stock 460 w a set of worked dove heads and a comp 305h cam, ran 12 flat w no issues.....slapper bars, no cage, no subframe connectors etc.

when I put the 10.00 deal in it I did a 10pt cage and ladderbars at the same time. cant tell you what it will handle in stock form

Ashburner wrote:Maybe I should try some lotteries
What do you think how much power the chassis can handle with the full subframe connectors and traction bars?

I would think about 500-550 would be the limit. I wouldn't push it anymore. It also depends on what you are going to do with the car. Street during the week and drag racing every weekend???It may not make it to far. Especially if you add transbrake or put a lot of shock to the car such as (candycane) burnouts or donuts in a parking lot. If I wanted a street 69 mustang,I would probably go with a 500hp engine with a 100 shot of nos in case I needed it.......

if this is a street car with a street tire you wont hurt the car,give it hell.....

I do have a detroit locker differential and 235 (9,25") wide street tires. I never use drag race or wider tires, forgot to mention that.
Usually its about 90% street and 10% drag race use.

Both Summit & Jegs offer a slightly better price on what looks like the same C/E 2109 slapper bars as in the mustangsunlimited link.

As for the sf connectors from mustangsunlimited, I can't really comment on how good they might/might not be. I have never had to buy a set of "store bought" connectors, I always just made whatever sf connector I needed out of tubing.


The black/gray Maverick with a 302/C6/bottle combo on my youtube page link was a good example of a dirt cheap "low buck/back yard" suspension setup with a 6 point bar that most likely still had a ton of room to grow HP/TQ wise. It just had simple 2x2 subframe connectors & mini tubs (made buy the car's owner), an old/used roll bar kit for a Pinto we re-bent to fit his Maverick, leafsprings moved inboard, trimmed rear frame rails, slapper bars, a 9 or 10 inch slick, and a slighly narrowed 9" housing w/back brace. The roll bar was added more for supporting the moved leafspring boxes than anything, and the thinking the car might get more/bigger power later. The roll bar would have probably been over-kill without the moved springs/mini tubs mods.

[edit] The yellow 69 Mustang on my y/t page is owned by the same guy that owned the maverick. At the time the videos were shot the Mustang with a junk 460/C6 combo only had sf connectors & Moroso "floater" ladder bars and no cage.

what do you guys think about the maier racing kit?



looks not to bad in my opinion. and I also think round pipes are better than square ones in this application. what do you think?

Ashburner wrote:what do you guys think about the maier racing kit?........

Hard to say, never dealt with that kit. Without a roll bar/cage round tubing SF connectors and/or connectors that don't weld in through the floor might be OK for a lower torque small block application, but do sound kinda scary (to me anyway) when bigger torque numbers are involved.

I'm going to build my own subframe connectors anyway, but I'm trying to
Find the best solution for my application. Would it make sense to weld the subframe connectors to the floor right under the seat console, in the middle of front and rear frame rails? If so, I could do that. A frame inside the car is not possible due to the classic car regulations here in Germany. I would loose the special registration then and pay taxes like sick. And yes, I'm German BUT a quarter American (what I'm very proud of)

Ashburner wrote:I'm going to build my own subframe connectors anyway, but I'm trying to
Find the best solution for my application. Would it make sense to weld the subframe connectors to the floor right under the seat console, in the middle of front and rear frame rails? If so, I could do that. A frame inside the car is not possible due to the classic car regulations here in Germany. I would loose the special registration then and pay taxes like sick. And yes, I'm German BUT a quarter American (what I'm very proud of)

If you can't have the connector body "through the floor", but still want to weld the floor to the connector in some way, and can fit the connectors tight enough against the sheetmetal floor you can either......

(A) Drill holes through the floor above the connector body and plug-weld the floor (through the holes) to the top of the connector body every few inches (or wherever the two touch) from inside the car.

(B) Stitch-weld the underside of the floor to the top of the connector body every few inches (or wherever the two touch) from under the car.

I would at the least add a set of SF connectors and if you want to add anx brace to stiffen it further. These cars like to twist with much over 400 HP especially with sticky rubber. Also wann make sure all your torque boxes are in real good shape and carefully and fully welded. Also an export brace and monte carlo bar up front. The X brace should be a quality piece made of thicker material than the Chinese repro stuff. Dont ask how I know.Alsothe recommendation for Caltracs is a real good idea as wheel hop will break parts especially with the HP you wnat to have under the hood. Take your time and build it right.

cool40 wrote:if this is a street car with a street tire you wont hurt the car,give it hell.....

True enough from what I've seen. On street tires, my buddy's 514 Mach 1 would just heat the hides in any gear (C6). With sticky tires on a well prepped track, watching it launch would make a classic car lover cry.

Ok, so I´ll use traction bars and build subframe connectors similar that the maier picture above.
The car will never run on slicks or drag tires. Only street tires

But I´m always open for new ideas..