L-head power improvement

http://www.film.queensu.ca/CJ3B/Tech/LowHoodFHead.html

 

Found this article. Alot of good info.

http://www.42fordgpw.com/images/hotrodL134.pdf

 

Makes me want an F-head now. You all know I enjoy making too much HP out of 4cyl motors.

Dangit when can I start my next project vehical?

 

I switched out the 2x4" aftermarket paper air filter with a K&N. I picked up about 3-5 MPH! I have a bigger cone filter now.

 

Installed a 2.2 chrysler turbo on a L Head a few years ago ran like it was a V6 . Had no problems even with 15 psi boost .Bill

 

trying to hotrod an f head is like feeding rolled corn to a donkey, it ain't never gonna be fast.

JB

 

Yeah, but when your donkey has to carry a buncha stuff over rough terrain, isn't it nice to know that you have a higher-powered donkey?

I like the old hot-rodding article. Particularly interesting was the paragraph where he redrills the hole in the cross shaft to make the clutch pedal easier. Hmmmmm.

 

I would only do it just to see how much power I can make. Modern 4cyl motors are easy to boost power in this would be a whole new challenge. All I would be looking for is 100hp anything more then that would be gravy. But then again that means I need another project vehical.

 

Do you have any pics of it installed. What else did you have to do to make it work? What carb did you run? Sorry for all the questions, I think this is very interesting and would like to learn as much about as possible.

 

No pictures sorry . Made our own exhaust manifold out of .120 wall stainless tubing and fabricated a custom intake also .Used a 938SD YF carburetor . It was a draw thru set up if I was going to do it again I would probably do a blow thru set up for the carb. It did run good though with stock gears and a warn overdrive you could cruise 60mph all day and not have to down shift on the hills .Bill

 

Fantastic old article on Mr. Hickey's project. Love that old time hotrodding stuff. Most of that work is still the basis of what you might try today, some of which would apply to the F-head too. The crappy combustion chamber design and it's tendency to detonate at what now are considered modest compression levels would be one big limit I'd think. Hickey ran into this too. Bill's (SVE perf) 15psi of boost is impressive, and that it held together is even better. What kind of ignition mods and timing were needed to do that? What CR did you use?

 

stock compression ratio 6.48 to 1 ran at stock timing (5 degrees BTDC) with stock ignition . With a forged crank and rods and the bearing sizes this motor has you could probably double the horsepower safely .The biggest problem with this motor is the oiling system it just can't keep up with the heat generated in the bearings at anythng over 3500 rpm for long periods. As long as you keep these motors below 3500 rpm they will last a long time .Bill

 

Where would you find a forged crank and rods for this thing?? :? They dont exactly have a ton of aftermarket support...

 

Stock! Many (most?) engines from this period had a forged steel crank. The cast crank is a newer development.

 

what's a long time ?
I ran mine for 8 years, daily, and drove it to Jeep runs and back home again.
The F4 engines are very tough and durable. And if you mistakenly install an L4 camshaft into the F4, you have a real screamer.......until the intake rockers start to break.... been there, done that.
Mine was constantly over 4000 RPM when in the dunes or running the sand drags (yes, it was balanced)
on the freeway, with the overdrive and 5:38s, that 3500/3700 RPM range was where it ran the best. On road trips from here to Colorado, that's where it ran all the time. No oiling/engine problems here.

ymmv

 

That's amazing. With that kind of an increase in combustion pressure I'd have figured the stock ignition would just get overwhelmed. The piston speed at 4k is too high for safety if you do the calcs. So that rules out raising the rpm in the hunt for power. I don't think any big bore pistons are out there, so serious displacement increases are out, unless you could stroke the crank. That leaves better flow through the intake/exhaust and/or forced induction left to try, which we now know works. So maybe an external hi-perf oil pump and some porting of the oil galleys and passages might gain a margin of safety.
Fun, aint it!

 

YEP!!! :twisted: :twisted:

 

Jeep say's that the redline for the "L" and "F" heads is 4000 rpm. Yes the later "F" head oil pumps are higher volume which will allow you to run at higher rpm's longer but a stock motor shouldn't be run over 3500 for long periods. Believe me my customers that don't believe me or care end up back at my shop. I firmly believe that these motors are tough and as long as you respect the fact that these motors don't like high rpm's you will be fine . To over come the breathing problems that they have some form of forced induction seems to be the ideal solution for more power. Bill

 

Ok, since we've started talking about F134s here's my $0.02 as I've been very happy with my mods. Focus on breathing and keep the RPMs down. Port the head and block. Polish combustion chambers. Ditch the factory exhaust manifold; headers or build your own - mine is made out of black pipe and fits in place of the cast iron piece. No oil bath - Donaldson paper element cleaner off an International 364 tractor. Use electronic ignition.

IMHO the factory oil pump is more than adequate, but the factory plumbing that passes oil to the engine is terribly restrictive. My system passes oil out the cover plate end of the new pump through a filter and back in through separate pipes at either end of the oil galley. Gauge shows about 45 at hot idle with 10W-30 & no pump mods.

I've been wanting to experiment with a turbo - not for power (this has plenty for me) but to keep sea level rating at 10,000 feet. Engine should hold up fine to 5 pounds of boost. Would post pix but too computer stupid...