428 cj

[Unit 5302]

A properly driven stock Boss 302 can hang well into the 14's. The reason it's not a quarter mile monster is that with valves larger than that of the 428, or even the mighty 427, it needs serious RPM's to hit it's powerband. Below 4000 rpm, you're not going anywhere.

That makes the Boss particularly difficult to get a good launch. Much below 4000rpms, you get bog, above, wheelspin. The gearing was not set for optimal 1/4 mile performance either. The suspention is also set up for road racing as well. I wouldn't doubt the Boss loses 1/2 a second in the 60ft alone. Making that up at the end of the quarter is difficult.

Also the fact that the Boss 302 is a semi-hemi like the 351C it's going to be all the more nose heavy.

In reality though, I don't own or drive one, and my uncle hasn't raced his yet, so I can't tell you what he has been able to get out of his. All I know is what the de-tuned version had for hp.

I'm sorry I misread your post about the hi-po 289. I just re-read it and I don't know where I got that info.

You indicate that the Boss 302 tested had the speed to run 13's, and that is probably coming away from the 60ft several mph behing the new GT. Making up that kind of ground takes serious hp.

[hehhehmule]

Agreed, a car would need serious horsepower to overcome an early deficit. But 364hp would be ample to overcome any advantage a 260, or even 225hp, engine might have in the initial 60ft. I do wonder why your uncle would have a 9:1 CR on a NA Boss, as one with the cavernous valves you refer to had a 11:1.

[Unit 5302]

I'll have to wait and see if my uncle gets the boss to the strip. He doesn't have the 9:1 CR, that's his buddy who had his motor dyno'd at the shop my Uncle had his engine built as well. The 9:1 motor had low compression piston's and the 1970 heads. In 1970 model's the Boss came with puny 2.19" intake valve's . The reason the other guy's motor was detuned was so that he could run it on 87oct pump gas.

My uncle's Boss has ported 1969 heads, and a mild comp cam, since the engine was disassembled and had no cam in it. He did say it's really short on go under 4000rpm's. That, with the stock rev limiter would imply a narrow powerband.

400hp (gross) would probably mean 340hp (net) and roughly 290hp at the rear wheels on a Boss. Given the fact the more hp you make at the crank, the more you lose in the driveline from friction and drag, the net difference is always going to be smaller than the gross difference in hp. I'm not sure what the 1969 Boss weighed, but I believe the semi-hemi 302 was pretty heavy. The net difference in HP between the cars would be less than 50hp. According to your numbers on the 4.6L SOHC, which would seem a bit high?

Anyway, I hope you don't plan to argue 50hp on a heavier car, with a poorer start, and with a smaller powerband, should mean more than an equal trap speed.

If the Boss was launched well, and had the correct gears, 13's should be in reach.

Fortunately, the 428 big blocks aren't so fussy about powerband, they don't weigh much more, and they ARE geared for the 1/4. They routinely ran mid 13's bone stock in the Mustang.

The net numbers and rear wheel numbers are guestimates, based on less power loss from gross to net on a Boss due to lack of power steering, A/C, or large alternator. The rear wheel power is reflected in the fact the Boss never came with an auto.

[hehhehmule]

Actually, Unit the Boss 302 weighed less than the new GT. The numbers I have on the 69 with the 302 put it at just under 3400lbs, with the big block going out at just over 3600. The 302 Boss's hemispherical characteristics, were limited to the head design. The boss shortblock is slightly heavier than a standard 302 because of it's metalurgy and the 4bolt main, but not enough to make a major impact. I hope you don't think I'm trying to be confrontational, it's just that I'm very tickled a legitmately hot topic has popped up in CLASSIC. I thought there for a couple of days this one was dead. WHEW!!

[Unit 5302]

Ah hell, now I'm gonna have to go look for weight numbers. The 1969 and 1970 'stangs were pretty large.

Cast iron hemi heads were heavy as hell. That much I know.

Still even if they are about the same weight, 50hp isn't an ungodly amount.

[hehhehmule]

Sorry to make you dig into the archives Unit. But one more point of debate arises here. Now you are comparing rwhp and making it only 50hp. That, even by your deductions, would be more like 70, since the new 4.6 rear wheels at around 220 vs the 290 you're attibuting to the boss. Is your uncle running a msd or something to give it a rev limiter?

[mslcr]

*My uncle is the original owner of a 1969 Mach 1 428CJ with the top loader 4 speed. Stock it ran 13's. The quickest quote I've seen for a production Mustang was from Car Craft testing the 1968 1/2 Mach 1 428CJ with the top loader. 0-60 5.5 sec. 1/4 mile 13.56 @ 108mph. Those numbers might be off a little in the accuracy dept. being back in the day and all, but they are reasonable for a perfect run.*

I find the 13.56 ET a bit dubius, at 108 mph.
This, to me, indicates poor suspension or other problems launching. A car that can run 108 mph in 1320' should be able to do it in real low 12's.
poor launch & gobs of power!
just my $0.021
Bracket racer, and owner of "M" & "S" code '69 Mach 1's

[hehhehmule]

I currently run those trap speeds, but definately could not muster low 12's. Low 12's with 108 traps would require ALOT of gear and MAJOR traction.

[mslcr]

Interesting....
My research indicates (and proves to be really close in my case, and others I have witnessed)
A car capable of 108 mph in the quarter, can do it in 12.2 sec with a 100% effective chassis. If you make the power for 108, this chart indicates the next money spent would be wisely spent on the chassis. Weight distribution, sub-frame connectors etc...
Alot of room for improvement without tweaking the engine!

[hehhehmule]

That was the point I was making muscl, the gear and the hook would have to be pretty damn good. Let's suppose you had an effective suspension, and good meaty tires that hook, but you're running 3.08's or 3.27's or 3.55's or, well you get the picture, and you trap at 108. What are the odds you've turned 12.2?

[mslcr]

Indeed.
Wouldnt it have been great to have those magazine tests run flat out, without having to feather the pedals???
Or what if the tires of today would have been available back then!
Later, Tom

[les1]

either way this supposedly 230hp couldnt ever think about 108 mph in 1/4 i still cant get over those BS horsepower numbers they arent even realistic. so a 2 barrel 302 must really only have 70 horsepower.I do know one thing our old cars RULE!!

[hehhehmule]

Ah, the thread that refuses to die. I seem to remember a mid 70's 302 2v dynoing at around 115 at the wheels. That may not be exactly on target, but it was somewhere in the neighborhood. I think ford rated it at 140.

[Unit 5302]

Well I'm back again.

I have to post on this reigning opinion of well, the car goes this fast at the end of the quarter so therefore it could turn times like these. Such a scientific base involved.

Older Mustangs have poor weight distribution to say the least. Meaning intitial hook up is very poor, and better hook is availible with weight transfer. Unfortunately that thought is inconsistant with the reality that the Mach's and Boss' didn't come with racing slicks, they didn't come with perfect gears, and they didn't come with drag suspensions. Therefore, your idea that under perfect conditions it could run 12's is false. Furthermore, I find that the generalization regarding this theory is inaccurate due to the circumstances surrounding different car and engine charachteristics. Are you saying that under perfect conditions a car that has a powerband between 6000-8000 should be able to pull the exact same time as a car with a powerband between 3000-6000 when they both finish the quarter at 100mph?

Here is how it fails. Car 1 hooks well, and has excellent weight transfer, it's high power band requires the engine to wind into it. That causes loss of performance off the line. Since it is already losing time, but has traveled a short distance because of the slow initial take off. Therefore, after a few seconds it has a greater distance to use it's power and close ratio tranny to accelerate to that speed.

Car 2 Takes off, gets excellent traction and weight transfer. Due to it's lower powerband initial acceleration is excellent. However, the car doesn't have the hp of Car 1. Due to it's excellent acceleration out of the hole, it has traveled further in the first few seconds. Through the remaining quarter the car manages to finish with a terminal velocity the same as Car 1. So what happens at the end of 1/2 mile. Same result. No frickin way. Distance/speed is not accurate to jugde ET.

Now on to the rev limiter issue. From what I understand, the Boss came stock with an ignition rev limiter.

The 302 in the Mustang II had 139hp net stock. They also made 248lb/ft of torque at a mere 1800rpm. It had a two barrel 369cfm carb if I remember correctly. Sorry about the misquote on net hp for the new GT. I thought I saw someone post that the car on the dyno tested at 240.

[hehhehmule]

Woohoo! I thought my favorite post was dead. It's alive, IT'S ALIVE!

[thunderbolt]

Since this is the raging post for FE big blocks I thought I might put my question here. Anyone know anything about 428's used as pumping motors. I ran accrost two of them yesterday. The id tag says 428, and the intake manifold casting number starts with d1. Does anyone know anything about these motors. Are they originally 428 blocks, or 391's bored to 428 specs? I understand truck cranks and passanger car cranks were different in the front snout area? How would I tell these apart? Thanks

[hehhehmule]

I'm reaching here a little Tbolt, but I can give you what I THINK, no KNOW. I'm pretty sure the 428 went out of production in 70. I'm not sure about the casting numbers on an intake, but I know a D1 block is a FT block and represents blocks cast in D-70 1-last year digit. I have no idea what ford might have done outside the automotive industry with the FE so take this all with a grain of salt. One thing I can tell you is the FT cranks have a larger diameter snout. If I remember correctly they're around 1 3/4 inches while the FE's are closer to 1 1/2. Sorry I don't remember the exact specs, but I think its pretty close to 302 intake size 1.78 and 1.45 but I'm not sure.

[les1]

no cjs in 71 and they might be regular 428's and the cjs had 4 bolts mains 2 on the caps and 2 from the side..run the block codes on the block and heads...oh and yes a 428 ran12.3 at the 68 winter nationals ha..

[hehhehmule]

Les, you're thinking of 427's they were crossbolted. 406's were the orignal crossbolted engine. 428's were 2bolts.

[Unit 5302]

Well, I thought I'd hunt this topic down for you hehhehmule, since it is your favorite on classic mustangs.

Unfortunately, my uncles Boss is having some motor problems, he found metal shavings in the oil filter, so it may be a while before he can get a run in at the track. He did say that it doesn't seem to have the power that his Mach 1 has dispite several small upgrades that have improved it's performance.

I'll still try and keep you guys posted on this scenerio.

Later,
Unit 5302