morph'n a 2.25 to a 2.5

[scott]

i hear that the bore of the 2.25 and 2.5 are the same. it's the thow that's the difference. anyone ever put a 2.5 crank and rods in a 2.25? there's a company, in england i think, that sell/does mods to old rover motors that push the hp up to over 100. i've been to there site before but can't find it now. do any of you guys know who i'm thinking of?

[sven]

The 2.5 crank uses 5 main bearings. Yours is only 3 bearing. So I dont think that will work.

[greenmeanie]

Automotive Comp Remanufacturing or ACR are who you are probably thinking of. They claim 112hp but for the kind of money they want to get you there you could put in a comparable engine for half the price.

[scott]

The 2.5 crank uses 5 main bearings. Yours is only 3 bearing. So I dont think that will work.

i've heard some of the 2.25 had 5 mb. i've had the sump off but don't remember. i'll have to check it tonight.

[yorker]

yes some 2.25's are 5mb. Once in a while you run across them but the odds are that yours is a 3mb unless it was replaced in the last 25 years or so.

[Leslie]

Most would probably pick a 5mb over a 3mb, but, I'd take the 3mb myself..... yes, 5 main bearings are 'better', but, they didn't do it because it was, they did it because they thinned out the walls (hence the reason the 5mb has the casting ribs on the side of the block).... the 3mb should actually be a bit stronger.

[sven]

Ive redone the head on my friends 2.5 hybrid series. We also fit a new weber 32/34 on it that took forever to find. That carb was big bucks too and is specific for the 2.5.

After all the headwork, new carb, and NRP exhaust the truck ran and drove sweet. But honestly, the power is very similar to my 2.25. If I were to redo my 2.25 (which I will have to do) I would just do it stock.

[Tim Smith]

I had an ACR engine in the lightweight when I got it but had to pull it when the knocking got bad and oil wouldn't stay in. The thing ran great with it but only got about 10 mpg and certainly was getting long in the tooth before the swap.

Since going back to a 2.25 that I had sitting around, I can tell you that my mileage is at least 50% better but the top end just isn't there. But the best part is that the 2.25 purrs with that sewing machine perfection. :D I just couldn't manage that with the ACR get up.

Not sure I'd spend the cash for a full on ACR kit myself unless I really wanted to keep the stock appearance. Although powerful, it felt like it was abusing the standard block (which in this case happened to be a 2.5 diesel block).

By the way, the ACR did get me past 90 mph (well +85 on 33"s) once or twice and I swear there was still more in it. But in all honesty, that really wasn't the best thing to be doing... :o

[Okar]

Thanks for the info Tim, I have a 2.25 diesel 109 pick up, was wondering whether to stay at 2.25 or go 2.5 I guess if i want to go fast, I'll do so in the Audi....:)

[Tim Smith]

Thanks for the info Tim, I have a 2.25 diesel 109 pick up, was wondering whether to stay at 2.25 or go 2.5 It's all in the pocket book and need for power. The standard 2.5, from what I've heard and read, isn't the power house drop in you might expect. If you really want to kick it up a notch you'll have to think about a 200 tdi, 300 or somthing a little more exotic.

As an aside, I believe the 200 bottom end is a very close relative to the 2.5 block. Which of course is a kissing cousin to the 2.25 5 bearing motor. The differences between the 2.5 and the 200 are mostly in the top end so you can draw your own conclusions.

Of course someone is going to prove me wrong on that one... and I hope it's with info more than the side webbing on the block. :sly:

I guess if i want to go fast, I'll do so in the Audi....:)You got it. ;)

I think the best thing you can do while the motor is out is to add in some sound deadening on the bulkhead. It's not so much that a well tuned 2.25 petrol is working so hard to keep up with the highway but rather the sound it makes while doing so is horrendous. And without some kind of sound barrier, you hear everything.

Not too sure about a 2.25 diesel and power but if you need some cheap power (and you don't care about the motor's long term life span any more) you could always add a propane injection get up. Woo Hoo! :D

[yorker]

Propane isn't very useful on a NA diesel vs. a turbo...

I thinkt he best bet is to accept it for what it is and enjoy it. It is a time machine- taking you back to a more serene- slower, and noisy-smelly time. ;)

[NC Rover]

Ive redone the head on my friends 2.5 hybrid series. We also fit a new weber 32/34 on it that took forever to find. That carb was big bucks too and is specific for the 2.5.

After all the headwork, new carb, and NRP exhaust the truck ran and drove sweet. But honestly, the power is very similar to my 2.25. If I were to redo my 2.25 (which I will have to do) I would just do it stock.

I have an original 2.5L and my buddy as the 2.25. The 2.5L has a bit more power...but not much when it comes to feeling the difference. The carb is a two barral. Putting a custom header on seemed to help out a good bit in my opinion.....

[scott]

parts are in! my old head had some repaired cracks so i went with a rebuilt 7:1 shaved to give a 8.5:1, a 2.5 cam and .060 over pistons. the only siezed parts were the MBs so those and the rod bearings are being replaced with .010 overs. shoud be picking it up in a couple days. the old weber 34/36 dgv will go back on and i have a 1.75" exhaust. i plan on having it dyno'd so i'll let you all know what the bhp turns out to be

[NC Rover]

parts are in! my old head had some repaired cracks so i went with a rebuilt 7:1 shaved to give a 8.5:1, a 2.5 cam and .060 over pistons. the only siezed parts were the MBs so those and the rod bearings are being replaced with .010 overs. shoud be picking it up in a couple days. the old weber 34/36 dgv will go back on and i have a 1.75" exhaust. i plan on having it dyno'd so i'll let you all know what the bhp turns out to be

Got any pics you could post up? I want to see some pics of your carb. I've having some "issues" with mine.

[scott]

Got any pics you could post up? I want to see some pics of your carb. I've having some "issues" with mine.

the carb and manifolds are laying on the garage floor. i'll post some pics tonight

[Tim Smith]

Propane isn't very useful on a NA diesel vs. a turbo... Really? I thought propane was to diesel motors as Nitrus is to petrol motors.

[SafeAirOne]

parts are in!...a rebuilt 7:1 shaved to give a 8.5:1, a 2.5 cam and .060 over pistons...

Sounds like you'll be rovering in no time :thumb-up:


BTW...I was just noticing your signature. Did you always have "(ret)" on there? I don't remember it... If that's new, then congratulations!

[scott]

nc rover, i took pics but with it out the linkage just ain't there. but basically what i did was mount my weber so that the linkage is to the left (i have a lhd). i had to mess with it for a while but finally got a real smooth movement through the full range of the throttle. when i get it all back in i'll try and do a movie clip for ya

mark, yes the (Ret) is new and feels great.

[greenmeanie]

Scott,
Do you still have your old head? If it is scap it would be fun to section it and take some pictures of the intake and exhaust ports. Not that it'll ever be a power house but a few pictures of these would be fun to duscuss in terms of flow improvements.

Cheers
Gregor

[scott]

Scott,
Do you still have your old head? If it is scap it would be fun to section it and take some pictures of the intake and exhaust ports. Not that it'll ever be a power house but a few pictures of these would be fun to duscuss in terms of flow improvements.

Cheers
Gregor

i still have it, was going to turn it into a lawn ornament. are you suggesting disecting it? that would be a heck of a saw job

[SafeAirOne]

i still have it, was going to turn it into a lawn ornament. are you suggesting disecting it? that would be a heck of a saw job

Naw...A hack saw and a couple of good blades and you'll be done in no time! :D

[greenmeanie]

i still have it, was going to turn it into a lawn ornament. are you suggesting disecting it? that would be a heck of a saw job

Yup, stick her on the bench, slice and dice. A sectioned head like the engines you see in those in museums would be a cool ornament.

I would probably use a grinder with a cut off blade and then clean it up with a file. It would be nice to see a cross section of the intake port and the exhaust port as it can tell you a lot about how these things flow.

Of course a few beers later a horizontal cross section through the remaining intake and exhaust port would be a nice little project but a lot more cutting.

Out of interest, does anyone know the intake and exhaust valve size on a 2 1/4. I'm not planning a hot rod but the power in an engine is in its ability to breathe.

[yorker]

Mmmm I'd love to see the head sectioned- someone have a good chop saw?

[scott]

have you chop happies ever looked at a stripped down head? the ports are pretty straight, you can see the valves and they're only in a couple of inches in. where would you cut to see what you want?

[greenmeanie]

Oh yes I've looked at them. It's the corner radii and the proximity of the water jacket that are the really interesting thing. A sharp corner results in a lot of shrouding regardless of valve size. It is usually the material thickness ovver the water jacket that limits your ability to blend the corner.

Quite frankly your right - I am chop happy. If its scrap its worth getting somethig useful out of it. If I was doing a cross section I would cut on a vertical plane through the center line of the valve guide parallel to the direction of the intake port.

There's some cool pictures on line of chevy stuff done like this and it is very useful in understanding the flow problems in that head. It is also useful to consider things like the throat diameter of the valve seat vs valve diameter.

Man, I sound like I'm going to hot rod a 2 1/4.

[badvibes]

Mmmm I'd love to see the head sectioned- someone have a good chop saw?

Scott-
I have a 14" chop saw if you're really feeling this ambitious... But was there any damage to the head? Might be something someone could actually use still.