150hp from a 250, that's reasonable right?

[Anonymous]

Well I just purchased a '75 250 that I had asked about on a previous post. Now that I have it, I would like to know what can be done to it to achieve 150hp. Actually I would prefer 170hp but I could live with 150hp. I have searched this forum quite a bit, but I find most people are shooting for higher numbers and therefore getting into more complicated stuff. By the way, this engine is going into an Early Bronco 4x4 so mid range power is what I'm really after. High rpm doesn't do me a whole lot of good when fourwheeling.

Is it possible to reach 150hp while maintaining stock compression ratio? Can I do it without pulling the head and having it worked on? I do not have to worry about smog equipment, and I have already yanked most of it.

This engine currently does not have a carb, so that is the first thing I will need to find a replacement for. So if any gains can be made by an "other than stock" carb, I need a new one anyway.

Also, I ran across a post that mentioned switching to a pre '71 timing chain set. The post gave the napa numbers as being S414 for the cam gear, B415 for the crank gear, and 9363 for the chain. When I did a search on napa I came up with S415 rather than B415 for the crank gear. Is this correct?

Now slightly unrealated, I am planning on switching this engine over to a made from scratch fuel injection setup in order to help with fourwheeling. I know that the intake log is less than ideal for making hp, but does it really affect anything when we are talking 170hp or less? I had originally planned on having the log machined off for my efi setup, but if it can feed 170hp I wouldn't need or want to. I know little about flow characteristics, so I do not know if that is something that comes into play mainly at higher horsepower, or if it is holding the engine back at all levels.

Lots of questions and I look forward to your answers,
Morgan.

 

[shmoozo]

If I might make an observation here, peak horsepower numbers are often misleading as well as largely irrelevant when discussing engines for 4-wheeling applications. I think what you'd really want to use as a goal is a torque curve. You'd probably do best with an engine that has a broad, flat torque curve, one that can produce good, strong torque from just a little above an idle to somewhere up in what would normally be regarded as a midrange RPM.

Having said that I would add that a 250 cubic inch Ford small six built and set up with that in mind and having the modifications required to produce a fairly healthy amount of torque for an engine of that displacement in that RPM range might just wind up having something close to 150 peak horsepower.

For example, if your horsepower peak came at, say, 3200 RPM and you were producing 250 foot-pounds of torque at that RPM (which doesn't seem completely impossible to me) then your peak horsepower would be about 152 HP.

The folks who know more about these engines and the limitations of their heads and such could probably give you some more accurate numbers as well as a bit of practical advice about how to achieve them and what that would cost.

One thing to keep in mind is the fact that on an engine like this one there's practical limits to what you can do within a given budget. If, for example, you're not prepared to spend the money needed to replace the stock cylinder head with one that doesn't have that integral log manifold then you'll likely find that intake log may force you to lower your sights a little. With that in mind, getting 200 foot-pounds of torque rather than 250 might be a lot easier and cheaper, and would still move an early Bronco with reasonable authority offroad provided you choose appropriate gear ratios for your axles and transfer case, and also that you eliminated any unnecessary weight from the vehicle.

Again, however, I'll defer to the experts here with respect to actual numbers, bits and pieces to modify or swap, and costs and such.

Sounds like an interesting and fun project. Hope it works out for you.

 

[Anonymous]

I should probably note that this engine will be driven on road a lot also. So that being said, slow speed trail conditions are not the only concern. I just wanted to make sure it was realized that this is not going into a car with goals of rev'ing to 6000rpm or high speed acceleration.

Just to put a number out there, let's say I'm wanting to spend $500 on this engine, and have it produce in the 150hp to 170hp range. Not to step on any toes, as I like inlines as much as the next guy on this board; but if a person can't put $500 into a 250ci engine and get it to produce 150 horsepower, well that's getting pretty pathetic. I thought .6 hp per cubic inch was a pretty low goal.

So if $500 will do it, what is best to spend it on? Oh, and my question still stands about the virtues of the intake in this situation, and whether or not it would be a large liability at this horsepower goal.

 

[Anonymous]

And let me clarify, 150hp at the flywheel.

 

[falcon60]

You've made it kinda' tough with a $500 limit.....but ASSuming the engine is in good condition I would go this way:
1: Camshaft,cause all these sixes need a better cam.Keep it mild.
2: Headers,cause they make torque and that's what you need.
3: YF,RBS or other "big" single barrel carb.Easy to mount and makes good torque. Cheap too.
4: Electronic ignition with proper advance curve for your use.

I think you'll get what you want from these mods if you have a sound engine to start with and do a good job tuning. You should see 1 ft/lb per cube in a nice wide powerband.

Terry

 

[Junk-Falcon]

ppp

 

[Broncitis]

Curious as to how you have resolved the oil pan issue associated with putting 250 in EB for my own endevours if I may ask. MIKE

 

[falcon fanatic]

FAlcon 60 gives good advice. But, I get the impression you don't want to pull the head or do any other major engine work. That rules out the camshaft. This is probably just as well since with $500 you can't afford to do everything he lists anyhow.

The headers and the ignition alone will get you pretty close to your full budget. You might want to take this opportunity to install the FI system instead of waiting. Four wheelin' with a carb can be a big PITA. At least in my experience. I remember a lot of stalling. there is a thread in the turbo and fi section about using a tempo or similar injection. Very easy setup, and cheap junkyard parts, (except for the brain).

By the way, I have a spare Duraspark system, complete, as well as an NOS Carter RBS carb. Cheap. PM me if you are interested.

 

[Anonymous]

Broncitis, I have done nothing yet as the engine is out in my barn, stripped down for a cleaning right now. The bronco has a 170 in it right now, so I plan on taking the bottom half of the 170 pan and welding it to the upper half of the 250 pan. And then relocating the oil pump pickup. I have not looked at them close yet to see what all this entails, but that's the great thing about working with metal, it can always be made to work one way or another. Oh, and I have heard of some guys taking a big hammer to the oilpan until everything fit. Somehow I'm not to confident in that fix though.


Does anybody have any opinions on the virtues of a new intake manifold design? I did not think it would be much of a factor at these low horsepower numbers, but I think I may have over-estimated the definition of "low".

Thanks again,
Morgan

 

[Anonymous]

And does anybody have an opinion on whether switching to a pre '71 timing chain really benefits anything?

 

[Anonymous]

you mentioned that spending over $500 and not getting 45 more hp is pathetic?

why is that? I see a vee8 get an ehaust system and chip and only get 20 hp (from what I remember)

a turbo might get you there in one shot, but even that is more that $500

what do you base that $500 cut off for being able to get to 150 hp on...is it budget or pre-concieved ideas that HP is cheaper on a six?

I am just confused...no offense meant. just clarification

 

[Anonymous]

$500 is just a number I made up to give you guys a ball park on what I wanted to spend.

My real point, or gripe, I guess, is that I had overestimated the factory horsepower for these engines. I thought they should have been pushing around 150hp from the factory, until I did my research and found the numbers to be much lower. I need to remind myself I am dealing with an old outdated '75 and not something more refined. So with that, I will just be happy with what I have and not waste the money on it, other than fuel injecting it.

Thanks for all your help.

 

[Anonymous]

I saw a porshe 90 last night on the RJ acutions wa sit...that had 85-90 horsepower

believe me, you can get these mustangs (or whatever) to move...and not too expensive if you do research and get there slowly...

do improvements by year, not by final dollar....

 

[Anonymous]

Put an OZ 2V head on your 250 ,that will give it 150hp , they look great too.

 

[ASMART]

Ignition 1st or you won't get as much out of the rest. DSii appears to be the favorite inexpensive ignition.

If no FI, direct mount 2bbl carb. Many have used 350 or 500 holleys.'

Long tube header if you can find one to fit. If not a shorter one would still help.

To fit in the $500 bal park you may need to purchase the carb on ebay or a swap meet. I am no expert but I am guessing this would get you close to your goal. If you really wanted to spend money, wait a couple of months and get Mike's Aluminum head. The you may have a hard time getting below 200hp.

 

[Anonymous]

I might look into the new head. In that case, this 250 is getting put on the back burner, I have too many other projects to take my money. I'll get a carb to hold me over until I finallize my plans on the efi. I'm going to get the engine painted up and looking good then get it installed into the bronco so I can get it back on the road.

Thanks again for the help.

 

[80Stang]

Used headers $150
Exhaust port divider $20
2V direct fit adapter $25
Good used Holley 350cfm $100
2V air cleaner Mr gasket or such $35
'69 timing set $40
Used Duraspark setup $120 (dizzy, coil, wires, module)
Some gaskets $50 (engine gasket set)
Have the intake valves back-cut $30
Have the head milled for 2V adapter $50
Porting tools (one or two porting bits for your air grinder) $25

$645. Some dollars over your ballmark but not too much. NOT a TOUCH on the block here. In addition, you'll need time. Go to a powerful air compressor and do some porting on the head. Buy the Falcon Performance Handbook and look into what you can do to the head.

 

[250mav]

wouldnt a '75 250 already have electronic ignigtion from the factory? my '1976 250 maverick has it stock

 

[Lazy JW]

... if a person can't put $500 into a 250ci engine and get it to produce 150 horsepower, well that's getting pretty pathetic. I thought .6 hp per cubic inch was a pretty low goal.

So if $500 will do it, what is best to spend it on? ..l.

Actually, a $500 limit is a pretty pathetic budget for ANY engine performance upgrade nowadays :roll:

However, IF the basic engine is in good condition you 'may' get close to your stated 150 but it WILL REQUIRE PULLING THE HEAD!

The primary limiting factor on these engines is the pathetic breathing ability. The stock cam is a MAJOR part of this limitation so it really must go away. This will get you closer to your stated goal than any other single item. A junkyard ignition and carburetor can help keep the budget down. Unless you can find some free headers they will exceed the budget.

A clever, talented do-it-yourselfer can certainly make good power out of this engine. There is no magic wand though, and EFI on a bone-stock 250 is not going to reach the stated goal either.
Joe

 

[mugsy]

Remember the 3 C's of Horsepower: Camshaft, Carb, and Compression. If you want a new cam in the little beastie, you'll need to pull the head. So milling the head at that point is not a big issue. Make sure you measure the combustion chamber volume, the deck height on the piston and figure on a new composite Felpro head gasket. As for the carb there are many ideas on this site; either a large one bbl or go with a 2V. Then there is the ignition upgrade. Only with a new curve will the engine produce more "seat of the pants" power. DS-II or the DUI will provide better reliability, smoother running and a small HP increase. And then what should be the first upgrade is headers/larger exhaust system.