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Unread 03-31-2009, 03:21 PM   #1
boinky
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Increase 225 V6 HP

Any suggestions on increasing the Horsepower on my 225 V6??

Thanks

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Unread 03-31-2009, 03:23 PM   #2
Mudweiserjeep
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Cam and 4 barrel carb.
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1987 XJ (Evil) (Parting out)
1970 CJ5
231 V6
2.5"bds lift, 0.75" shackle lift, 4:88 gears
31" Old tires..... need newer ones....going 35"
www.earlycj5.com
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Unread 03-31-2009, 10:10 PM   #3
John N
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Quote:
Originally Posted by Mudweiserjeep View Post
Cam and 4 barrel carb.
A cam, 4 bbl intake, a small 390 cfm carb and headers are pretty good without rebuilding the motor. Be sure to put in a new timing chain and gears, if they are old ones. Upgrade the ignition, remember it's odd-fire, don't get the wrong stuff.

The biggest constraint on this motor is that the heads have rotten flow for getting large HP increases. Unless you're really set on the 225, you money will be better spent on upgrading a newer 231 or 252 Buick V-6s, the heads are way, way better on these motors.
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Unread 04-01-2009, 12:23 AM   #4
jeepdaddy2000
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The greatest strength of the 225 is it's massive low end torque. This comes from the inordinately heavy flywheel. The downfall is a somewhat sluggish feeling motor due to it having to spool that piece of iron up. Just be aware that no matter what you do, it probably won't have the snap you would come to expect from comparable motors. That being said.....
A good dual plane manifold such as the Offy 360 or equivalent.
While there are many choices in carbs, my best performance has come from the Holly Economaster and surprising enough, the (small version) Rochester Q jet, which I'm running as I speak.
There are also some good cam grinds.
The stock crossover exhaust can be improved by splitting the exhaust. If you go this route, you will need to find a left manifold from a car application. If you have the stock Ross style steering, this is going to create some clearance issues, which might be better addressed by fender well headers.
HEI ignition. This is by far the best "bang for the buck" upgrade you can install. These can still be had new or used. You need to look for 75-77 Buick V6 applications. This will be a 231 oddfire application. As John N stated above, be double dog sure any ignition parts you get are for an odd fire.
Remember to insure all your performance engine upgrades not only compliment each other but fit your wheeling style. Otherwise you will not be happy with the result.
While some don't like them, I installed a Melling high volume oil pump about twenty years ago and felt it to be an excellent upgrade. It pays dividends for me due to the fact that most of my wheeling is from below to off idle.
TA performance seems to be the Buick outlet source these days since Kenne Bell gave up on them.
Earlycj5.com has an extensive database on the 225and the folks over there are great.
Enjoy your engine, there are, in my opinion, the best motor Jeep ever offered in the CJ.
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Unread 04-01-2009, 06:55 PM   #5
boinky
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Thanks!!! I just bought this one and it has a 225........I am used to the straight 258...

I noticed exactly what you were talking about..
"The downfall is a somewhat sluggish feeling motor due to it having to spool that piece of iron up."

I will look into some changes!!
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Unread 04-01-2009, 08:14 PM   #6
my-jeep-earl
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The 225 is an ODD FIRE engine, so to keep it running smoother they stuck a 50+ lb flywheel on it, it will REV slower, I changed mine to a TH350 so I'm wondering how it's going to run?
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Unread 04-02-2009, 06:27 AM   #7
jeepdaddy2000
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Quote:
Originally Posted by my-jeep-earl View Post
The 225 is an ODD FIRE engine, so to keep it running smoother they stuck a 50+ lb flywheel on it, it will REV slower, I changed mine to a TH350 so I'm wondering how it's going to run?
These engines were offered in the Commando in front of a TH400. I've driven a couple and noticed no real difference in vibration. While not I can't be positive, I would be surprised these were running a "massive flex plate".
Boinky, there is an excellent book out there called (I believe) "how to hot rod your Buick V6". I owned one but it was "borrowed" by a friend many years ago and sadly disappeared. The real challenge is to find aftermarket performance parts. Many Buick 350 internals will cross over but such things as cams, cranks, etc..are becoming hard to find due to being discontinued.
Personally, the low end torque more than outweighs any "loss" of snap on acceleration. I have had mine pulling so low that I could feel each cylinder fire, and once spinning, these engines wull pull like gangbusters.
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Unread 04-02-2009, 10:32 AM   #8
Happy Joe
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Having had a number of 231s I would not hesitate to go with a fuel injected 231 to replace the anemic 225. It would fit in the same engine compartment space.

(Rant)
For some reason people seem to think jeep engines have "massive torque" they do not.
200 foot pounds is roughly what a determined person can generate by hand with a breaker bar or torque wrench and is obviously not "massive" torque.
(rant off)

As stated above; the apparently massive torque form the add fire 225 is due almost exclusively to the very heavy fly wheel used on these engines in a attempt to cover the odd fire vibrations which some folks find annoying.
The weight of an oil filled torque converter brings the rotating mass of automatic transmission equipped vehicles into the same range as the heavy flywheel. Since the torque converter is bolted to the flex plate the combined weight of the two needs to be considered.
The flywheel has a downside of limiting the rate of rpm change and while good for low, constant speed operation definitely makes the acceleration slower and the engine feel less peppy.

The more modern 231 or its larger brother is available with much better cam, heads, rods, pistons, distributor and the even fire version was made with fuel injection and DIS ignition. At a minimum 225 fans should upgrade their distributor to an odd fire 231 HEI distributor. (The 225 is a Buick engine, who's tooling was sold to AMC and was later sold back to Buick and was used as the basis for the widely used 231 V-6, for folks that did not know).
The downside for these engines is the weak bottom end of the block (the internal bulkheads can be visibly flexed with a large screwdriver/small pry bar) and a poor oiling system. A bearing girdle should be strongly considered if horsepower in the 200 range, or over, is attempted with these engines, IMO.

Enjoy!
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Carburetors became obsolete during the last century... do what ever it takes to get fuel injection...It makes bigger grins off road.
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Unread 04-02-2009, 03:40 PM   #9
PavementPounder
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Smoking deal on an unused Offy Dual-Port 225 intake:

http://reno.craigslist.org/pts/1101138406.html
offy2251.jpg   offy2252.jpg  
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Unread 04-02-2009, 08:37 PM   #10
boinky
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Thanks again..........have not noticed any vibration at all.........I'll keep looking and searching.

Just traded last weekend.........so Ihave plenty of time to look things over.

As of right now, I have no intentions of changing the motor......just trying to give it a little more HP>
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Unread 04-03-2009, 09:43 AM   #11
Happy Joe
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Quote:
just trying to give it a little more HP>
Find a copy of "The Buick Free Spirit Power Manual" and read it.

Change to the odd fire 231 HEI distributor,
change to the late 231 heads; Verify that the cooling ports to the block line up first.
do a quick port grind to clean up the area immediately around the valves,
Install tulip valves and a 5 angle valve job.
Install decent valve springs (at least 90 to 110 lbs when closed),
Change the cam to one with decent specs for towing,
Install a Cloys tru-roller timing chain at 4 to 8 degrees of advance,
change the rods to the late 231 rods, (shot peen and magnaflux the rods before installation)
Install a good grade of hypereutectic pistons, avoid chrome/molly rings they can be a bear to seat properly,
find a GOOD Rochester 2GC 500 cfm 2bbl carb off of an old 350 Chevy pickup and rework it (worn out parts will have issues). Note; this may require grinding on the intake manifold to allow for better flow immediately below the carb.
Install fully grooved main bearings and a high volume oil pump.
Rework the oil passages in the timing cover to get better flow,
Install the longest primary length tube headers (30" or longer) that you can find (you want a relatively small primary tube, 1.5" or smaller) shorty headers will increase flow but do noting for torque except at very high rpm.

It would be cheaper and easier to change out the engine...
If you hop it up and hot rod it with the current rods and pistons; expect it to come apart...

Minimum changes;
HEI odd fire distributer,
late (80 or newer) 231 exhaust manifolds, this will probably necessitate a new exhaust system...
Rochester 2GC 500 cfm carb.

Enjoy!
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...a well prepped, well driven, vehicle should do well in any terrain, including the highway.

Carburetors became obsolete during the last century... do what ever it takes to get fuel injection...It makes bigger grins off road.
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Unread 09-24-2009, 09:56 PM   #12
TURRBO387
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Yeah I Have A 225 V6 Myself And Eldebrock Makes An Excellent Package For This Motor! Cam, Lifters, 4 Barrel Intake, And 4 Barrel Carb! I Have Built Mine Up High Performance For A Swamp Buggy I Have Built Out Of A Cj 5. I Put A Davis Unified Ignition System And The Edlebrock Performer Package On It And The Horsepower Increase Is Immaculate! I Also Bored It .020 Over And Put New Timing Chain And Gears. Next Step Is A 231 Head Conversion. If You Want To Increase Horsepower For A Reasonable Amount Of Money The Eldebrock Performer Package Is The Way To Go And Then Some Type Of Hei Distributor.
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Unread 10-04-2009, 11:02 PM   #13
carnuck
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The torque converter acts as that "massive flywheel" to smooth things out.
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Unread 07-06-2012, 03:26 PM   #14
slalomwy
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Anyone had problems putting a 4br on a 225. One of my neighbors had one and said he couldn't pull enough vaccum over 6000ft. I am getting ready to put a Holley Truck Avenger 470 cfm on mine at the moment.
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Unread 07-06-2012, 04:12 PM   #15
jakeryii
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holy thread from the dead batman, and 470 seems a little much for this baby v6
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