How would you achieve 320+HP from a 401 in a Jeep?

Nikkormat · Post by **Nikkormat** » Sun Apr 02, 2017 6:07 pm

So let's say hypothetically I wanted to double the amount of power my Wagoneer has. Stock it was rated at 160hp so that should be easy.

What I have is a .040 over 401 with lightly ported and polished (basically just cleaned up) 502 low compression heads. A summit K8600 and for now a stock intake and a 500cfm carb.

What would you change to push that north of 320hp while remaining street and off-road friendly and keeping enough vacuum to play nice with fuel injection?

What should I expect the power output of my current setup to be?

ShagWagon · Post by **ShagWagon** » Sun Apr 02, 2017 7:13 pm

Do they make a supercharger?

Might even help on gas mileage if you keep your foot out of it. Plenty vacuum I'm sure as well.

az chip · Post by **az chip** » Sun Apr 02, 2017 11:06 pm

Put in a big block chebby motor.

hutcho · Post by **hutcho** » Mon Apr 03, 2017 10:05 am

LS swap it.

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WT91 · Post by **WT91** » Mon Apr 03, 2017 10:28 am

http://theamcforum.com/forum/my-pos-401 ... 44174.html

letank · Post by **letank** » Mon Apr 03, 2017 11:02 am

Check this

http://ifsja.org/forums/vb/showthread.php?t=127321

shimniok · Post by **shimniok** » Wed Apr 05, 2017 5:08 pm

Higher compression and long tube headers for a start. And the right cam. So says desktop Dyno.

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Post by **fulsizjeep** » Wed Apr 05, 2017 5:18 pm

You are going to lose some low end torque with the changes to get 320 hp. Could just put another 401 in the cargo area and run them both stock.

Nikkormat · Post by **Nikkormat** » Wed Apr 05, 2017 5:33 pm

fulsizjeep wrote:You are going to lose some low end torque with the changes to get 320 hp. Could just put another 401 in the cargo area and run them both stock.

One for each axle! I like it...

Nikkormat · Post by **Nikkormat** » Wed Apr 05, 2017 5:38 pm

Alright I've done some more reading and math.

My stock 360 was more like a pathetic 140hp. And less than that due to the flat cam.

A stock 502c headed 401 is good for 250 or thereabouts.

With port matching on the intake side, the higher revving cam, a bump in compression ratio, and timing set for performance instead of emmisions I should get to 280 or better easy peasy.

If it's as peppy as Blake's 360 I'll be happy. https://youtu.be/589tcFg043o

Post by **fulsizjeep** » Wed Apr 05, 2017 5:57 pm

What is a stock 502C head?

I can't view the video but I can say Blake's 360 is pretty worn and has been for a while. Maybe he has done something to it in the last couple years. The FI gives it some UMPH just from better throttle response.

Nikkormat · Post by **Nikkormat** » Wed Apr 05, 2017 6:00 pm

fulsizjeep wrote:What is a stock 502C head?

I can't view the video but I can say Blake's 360 is pretty worn and has been for a while. Maybe he has done something to it in the last couple years. The FI gives it some UMPH just from better throttle response.

1973-1974 401 heads. Flow best stock, especially on the exhaust side, and are a 58cc chamber instead of 63cc on the later heads.

Blake's 360 may be a little worn out but it's still miles ahead of where I am now. And it is fully capable of launching the honcho in a very impressive way.

Post by **fulsizjeep** » Wed Apr 05, 2017 6:10 pm

The heads to have were made for the 340 HP 390 Machine engine. They were also used on early 71 401s. The head casting number is 3196291. I have a set of these. They are 50.60cc.

Nikkormat · Post by **Nikkormat** » Wed Apr 05, 2017 6:14 pm

fulsizjeep wrote:The heads to have were made for the 340 HP 390 Machine engine. They were also used on early 71 401s. The head casting number is 3196291. I have a set of these. They are 50.60cc.

Well unless you want to part with them, I think I'll have to stick with what I have.

The 291's are favored for there bump in compression but the 502's outflow them.

WT91 · Post by **WT91** » Wed Apr 05, 2017 6:21 pm

I don't think Blake has really touched it much, at least if I'm following his build thread right. Last time I checked his thread out, I thought he just had a cam and EFI. His gearing is what lets him get the tires turning in the video you posted, but the man himself would have to comment on that.

I think a 401 with a healthy stock rebuild, slightly bumped compression, intake, exhaust, good ignition, decent cam, you'd have plenty of power on tap. HP sells cars, torque turns the tires.

shimniok · Post by **shimniok** » Wed Apr 05, 2017 6:26 pm

I feel like a flat torque curve is probably more important for normal driving vs peak HP at high RPM.

My other thought was to pick optimal gearing. So I think I am headed toward a OD trans of some flavor so I am not screaming on the hwy but can be in the 2500-3500 rpm power band when needed. I could just do an LT swap but I like AMC motors a lot

So my tentative plan is something like: long tube headers to improve midrange with 9:1 CR, a 260-ish cam with a bit wider LSA for TBI, 4.10's (or maybe 4.56's) and maybe 4L60E and switch to the newer PCM. And maybe go back to the Edelbrock intake too.

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Post by **fulsizjeep** » Wed Apr 05, 2017 6:28 pm

From my experience, the bridged rockers on the 502 are less than desirable for more horse power. The aluminum bridges are crap. The steel ones can warp. If you are going to stud the rockers, that is another story.

Nikkormat · Post by **Nikkormat** » Wed Apr 05, 2017 6:35 pm

fulsizjeep wrote:From my experience, the bridged rockers on the 502 are less than desirable for more horse power. The aluminum bridges are crap. The steel ones can warp. If you are going to stud the rockers, that is another story.

The steel bridges are doing OK in the Cherokee's 401. I broke the aluminum bridges in it. And all I have for this engine is the steel bridges.

If it were in the budget I would go to the individual rockers without question. Like I said I don't have a set of 291's to play with. I've got 502's and some 1978 344? heads.

Post by **fulsizjeep** » Wed Apr 05, 2017 6:38 pm

OK. I am going back to putting another 401 in the cargo area.

Nikkormat · Post by **Nikkormat** » Wed Apr 05, 2017 6:45 pm

fulsizjeep wrote:OK. I am going back to putting another 401 in the cargo area.

A luxury only some of us can afford! If the Cherokee was drivable I could put two 401's in the trunk. But I'm sure you can do more!

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