2.25 Max RPM?

[Tim Smith]

Okay, so I did a search on the forum but all it picks up on is "2.25" no "Max" or "RPM" so figured I'd ask.

What is the maximum RPM one can get out of a 2.25 for top end highway crusing? I'm useless with figuring out the gearing numbers and wanted to know what my typical 2.25 is clanging away at when I'm doing say 65.

Again thinking about the engine swap issues here and know my Merc 300D motor should be good for over 4000 rpm. So theoretically, I'm trying to figure out what this would equate to as my highway crusing speed if I left the gearing alone. :confused:

Cheers,
Tim

[BackInA88]

Well I have an overdrive and 16" tires (235/85 R16) and I'm running about 3100 RPM's at 70 MPH.
I have run 65 without the overdrive but I didn't have a tach at the time.
I usually shift in to overdrive at around 60 because I feel it is screaming pretty well by than.:p
Tomorrow I'll check it for you.

[Tim Smith]

Well I have an overdrive and 16" tires (235/85 R16) and I'm running about 3100 RPM's at 70 MPH.
I have run 65 without the overdrive but I didn't have a tach at the time.
I usually shift in to overdrive at around 60 because I feel it is screaming pretty well by than.:p
Tomorrow I'll check it for you.

Thanks!

Thats good news for me I guess. I've seen the max HP rated at 4000 rpm but don't really know if that is the max rpm in general.

Don't blow her up doing any testing but if you can, let us know when the engine is sounding happy (and speed/gear if possible) and when it starts to sound like the 12 horseman are approaching.

Cheers,
Tim

[GrFa]

I asked this same question on another board and I think the concensus was not to run it over 4500rpm or so. I will be running 235/85/16 and no overdrive to start, with an ashcroft hi ratio transfer case that I could throw in.

[yorker]

I thought this info was on TAW's page? For some reason 4,200RPM sticks in my mind.

[Tim Smith]

I thought this info was on TAW's page? For some reason 4,200RPM sticks in my mind.

It could be on TAW's page but for some reason every time I start reading her site, I have the uncontrollable urge to just get in my truck and drive, or wrench or kiss it. Guess I've not got what it takes to figure out the numbers...

Actually, I've seen my truck at some unbelievable highway speeds and am really wondering what engine speeds I should be looking for in reality. And if I convert over what it would directly relate to.

Honestly, have you ever seen your truck read 85+ (very close to 90) while it was wearing 33" tires and in Roverdrive high? I think my numbers and experiences are probably acts of god, rather than what the truck was designed to do.

And I don't drink that much beer to make this up!!! At least I don't think I do.

[Tim Smith]

And I don't drink that much beer to make this up!!! At least I don't think I do.

After reading that, I feel that I have to explicitly say that I do not drink and drive. Bad, bad, bad stuff!:nono:

Only afterwards... like right now...:thumb-up:

Also, I used to think I was a smart guy, until I realized what was telling me that...:confused:

[Tim Smith]

I asked this same question on another board and I think the concensus was not to run it over 4500rpm or so. I will be running 235/85/16 and no overdrive to start, with an ashcroft hi ratio transfer case that I could throw in.

Yeah but how can you tell without an rpm gauge? I might have run my motor up to 4501 rpm once, but wouldn't know any better.

Now that I think of it, oh gawd! What could I have done? Perhaps I was the reason that last motor blew all it's seals and started knocking... Still it saved me from getting run over that day.

Cheers,
Tim

[TeriAnn]

What is the maximum RPM one can get out of a 2.25 for top end highway crusing?

I've too never seen an official red line RPM for the 2.25L petrol but I have seen power specs out to 4250 RPM.



I'm useless with figuring out the gearing numbers and wanted to know what my typical 2.25 is clanging away at when I'm doing say 65.

Well you can be thankful that I can't even seem be able to say good morning without supporting data. Series gearbox/ standard Series transfercase/4.7 R&P/32 inch dia tyres (stock 109 dia) 65MPH = 3686 RPM.

As it just happens, yesterday morning I revised my gear ratio web page to include engine RPM at 65 MPH in fourth gear with 32 inch diameter tyres for all the standard Series transfercase and LT230 versions and 4.7:1, 4.1:1 and 3.54:1 R&P ratios. At a glance you can see all the combination 4th gear ratios and the engine speed at 65 MPH for each combination of transfercase and R&P.

I also linked the web page with the RPM calculator I used to help people get numbers for different size tyres.

http://www.expeditionlandrover.info/gear_ratio.htm


Again thinking about the engine swap issues here and know my Merc 300D motor should be good for over 4000 rpm. So theoretically, I'm trying to figure out what this would equate to as my highway crusing speed if I left the gearing alone. :confused:

May I suggest an alternative? Find out the RPM range where the 617 engine is happiest and provides its best fuel mileage then choose gearing to get as close to that engine RPM as possible at highway cruise. It is going to take a great deal of work to get a 617 Mercedes engine to fit into a Series bay. It seems a waste to couple it to the wrong gear ratios. There's lots of bolt in combinations to choose from so don't settle only for what sorta works but stresses the engine every time you hit the highway.

Data is your friend:thumb-up:
TeriAnn@ nerds are us

[BackInA88]

Run it up to 65 without the overdrive this morning for you.
Looks like 3500 RPM's.
Looking to get me a 4000 RPM tach the 8000 RPM unit I had setting in the garage just doesn't cut it.:mad:
To me it was screaming for the overdrive.
Mine runs nice and smooth at around 3000 RPM's and can still pull itself up a small grade without loosing speed.

[Jim-ME]

I have always been under the impression that max rpms the same rpms that peak HP is achieved. If I read the RN catalog correctly a 2.25 L petrol engine peaks at 4,250.

[yorker]

If you like to crunch #s this site has some useful calculators:
http://www.grimmjeeper.com/gears.html

[TeriAnn]

It could be on TAW's page but for some reason every time I start reading her site, I have the uncontrollable urge to just get in my truck and drive, or wrench or kiss it.
Funny, me too! :)

A lot of that web site was written just after I came back from a trip or just after a Land Rover wrenching session when I wanted to document something before I forget for the next time I have to do that task. Some of it was written in leu of driving when the fuel tank and my pocket book were both empty :( and some when I just decided it was too cold or wet to work on my Land Rover outside.:eek:

My next computer will be a portable. I suspect I will end up writing a big photo & text journal covering my travels. I don't know if anyone would bother to read it other than myself though. If nothing else I could continue to write my book while on the trail.


Actually, I've seen my truck at some unbelievable highway speeds and am really wondering what engine speeds I should be looking for in reality.
While I'm a firm believer in the concept that reality is what you make of it, I've noticed that reality is strongly influenced by physics. Why not put a tach in you Land Rover? A couple of wires, a couple of screws and about an hour or less and your questions are answered more accurately than taking a poll of people with different configuration Land Rovers.


Honestly, have you ever seen your truck read 85+ (very close to 90) while it was wearing 33" tires and in Roverdrive high? I think my numbers and experiences are probably acts of god, rather than what the truck was designed to do.

:eek: :eek: :eek: :eek: :eek: :eek: :eek: The Land Rover engineers detuned the 3.5 V8 they put into production Series IIIs because they wanted to discourage drivers from driving faster than 65 MPH in a Series Land Rover. You were driving outside the safety design parameter envelope:eek: :eek:

When I had a 2.25L engine in The Green Rover I mostly cruised along at 55 MPH. Now that I have a 5L V8 and taller gearing, I mostly cruise down the highway at 60 MPH. The nice thing is that now I do it in the mountains as well. I think the fastest I've ever taken the Green Rover is 75MPH.

But getting back to 2.25 engine RPMs, having driven for a couple decades with a tach & 2.25L engine, I have noticed that a 2.25L engine seems happiest between about 3000 and 3400 RPM with 3200 being the sweet spot. With 32 inch tyres this means between 50 and 60 MPH.

My 5L V8 likes to loaf around in the low mid 2000 RPM range so I have raised my gearing accordingly. I bet a Mercedes 617 diesel also prefers to cruise at lower RPMs than the 2.25L petrol engine.

Be nice to your engine and your engine will be nice to you ... hopefully

[Tim Smith]

Run it up to 65 without the overdrive this morning for you.
Looks like 3500 RPM's.
Looking to get me a 4000 RPM tach the 8000 RPM unit I had setting in the garage just doesn't cut it.:mad:
To me it was screaming for the overdrive.
Mine runs nice and smooth at around 3000 RPM's and can still pull itself up a small grade without loosing speed.

Thanks so much for testing that for us! I had no idea the motor was actually going so slowly at that speed. It sounds so much faster when you are behind the wheel.

[BackInA88]

Yeah it sures sounds like it is screaming!

[Alacrity]

2.25 petrol Peak HP seems to be right at TerriAnns sweet spot - 3200 RPM, but nice broad top. Slight continual drop after - Max a bit short of 4200 rpm

http://www.flyinmiata.com/projects/installation_photos/basil_dyno.pdf

Engine:
2.25l gas engine
Pertronix ignition
Flamethrower coil (who could resist a Flamethrower?)

Not a fresh engine - smoked blue - curves should still be fairly valid tho.

Plenty of discussion on BenzWorld and other MB boards regarding best efficiency rpm and speed, 300D and others.

Luck
Alac

[Tim Smith]

...I suspect I will end up writing a big photo & text journal covering my travels. I don't know if anyone would bother to read it other than myself though...

I'd read it!

TeriAnn, your website has provided hours of enjoyment and loads of information for myself and I sure others as well. Thanks for all the time you spend on it. It's great stuff!


...While I'm a firm believer in the concept that reality is what you make of it, I've noticed that reality is strongly influenced by physics. Why not put a tach in you Land Rover? ...

Agreed. I've actually got a new tach in a box somewhere. It's filed under "When there is nothing else to do, do this stuff" and unfortunately I've just been swamped for a long time now. One of these days...



...You were driving outside the safety design parameter envelope:eek: :eek:

When I had a 2.25L engine in The Green Rover I mostly cruised along at 55 MPH. Now that I have a 5L V8 and taller gearing, I mostly cruise down the highway at 60 MPH. The nice thing is that now I do it in the mountains as well. I think the fastest I've ever taken the Green Rover is 75MPH...

You obviously have not driven the Green Rover on the Merritt Turnpike... :eek:

However the instance in specific was while driving through New Jersey, after having just bought the truck in Florida. This was my first drive ever bringing it home to CT but it was tight and powerful and it was probably giving me a sense of superiority at the time.

I'm sure I've told this story to the board before but I'm a bit of an egomaniac and just loving talking about myself. :p So here is the story again. :p :p :p

---
Merging back onto the Jersey Turnpike after a fuel stop and I had a trucker giving me a hard time (tailgating) and as I came into the merge zone I had only one open spot between some other big rigs. They too were going a bit too fast but I had to make a run for it!

Having made that merge, at this point I was doing something on the order of 70 - 75. My next decision to move into the middle lane was what brought me up to "ludicrous speed" but I really wanted to get out of this tight spot between the trucks.

Cars were zipping by and a jeep got into the mix in the middle lane, waving his thumbs-up in the air. Although he was enthusiastic about the old truck, he failed to see that I was in a tight spot with some high tonnage trailing not far enough behind. So as he slowed down to get another look from the back, I darted out in front of him. His thumbs up quickly turned to outrage, and we were off.

Peddle to the metal, my truck was actually still accelerating but I had a beefed up Jeep on my tail who probably had more than twice my power to weight ratio and I now wanted to get away from him. Traffic is still passing me in the high speed lane, but I'm catching up pretty quick. And there it was, the opening I was hoping for. If I can get into this opening in the high speed lane, the Jeep will probably get blocked-in by the car coming up in the middle lane.

Floor it.. Floor it... Bingo! Slip nicely into lane 3, pass the car in lane 2 and then swing back into lane 2 and then 1 again. The car in lane 2 screwed everyone up and so I was no longer the hunted prey.

It was when I slipped out of lane 3 that I noticed the speed. I distinctly remember seeing the speedo waving well past 85 and into 90 territory to which I exclaimed something like "Oh sweet lord, what have I bought!?!" The gears made most of the noise but the motor was also spinning away like a rapped ape. It sounded like the world was going to end.

I also remember looking over at the car driving along right next to me and noticing the expression on their faces. There was none. They had no idea what was going on inside the rover right next to them. I was defying logic, physics and sanity and they could have cared less. They found nothing remarkable about the bouncing ugly brick-like truck albeit with a smoke trail following it at this point and the driver gripping onto the steering wheel, pale faced and yet flushing at the same time.

They just had no idea what life was all about!

It was probably as much my own machismo that got me going that fast as I did. I could have just jumped off into the emergency lane, or something equally sally. But no matter what you tell me, I still say to this day that this truck saved my life. :)
---

The motor didn't last long after that. It did had the twisty 2.5l cam and some other bits to make it go faster but unfortunately it also leaked like a sieve from every seal, burned oil and had a scary knock at idle. I've since switched it out with an old standard motor I had sitting around.

I'm now a mear mortal again.


...But getting back to 2.25 engine RPMs, having driven for a couple decades with a tach & 2.25L engine, I have noticed that a 2.25L engine seems happiest between about 3000 and 3400 RPM with 3200 being the sweet spot. With 32 inch tyres this means between 50 and 60 MPH.

My 5L V8 likes to loaf around in the low mid 2000 RPM range so I have raised my gearing accordingly. I bet a Mercedes 617 diesel also prefers to cruise at lower RPMs than the 2.25L petrol engine.

Thanks TA! Thats what I was getting at.

I think the 617 is a high revving diesel but again my tach has been broken the whole time I've owned it. So again not sure what it likes to live life at. I do however see that it goes up to 6 grand... Hmm :eek:

Diesel Giant has a good few shots of the motor in action.
http://www.dieselgiant.com/diesel_videos.htm




...Be nice to your engine and your engine will be nice to you ... hopefully

Yes! Don't fly too close to the sun folks. :p

You might throw a rod.

[Jim-ME]

If I remember correctly any engine is happiest at 80% of it's max rpms for peak HP and it's HP for max torque. That is what is refered to as the power bandwidth. If you stay in the range your engine will be working at maximum efficiency(sp?). If you use 4200 rpms you get 3360 which isn't too far from the 3200 sweet spot which has been posted.

[TeriAnn]

I think the 617 is a high revving diesel but again my tach has been broken the whole time I've owned it. So again not sure what it likes to live life at. I do however see that it goes up to 6 grand... Hmm :eek:

Just because people can build an engine that rev's to 9 grand doesn't mean that it lives long there or gets its best fuel mileage there.

OK, I just took pity on you and spent 5 minutes doing a web search for Mercedes 300TD gear ratios & stock tyre diameter then ran the numbers. The Mercedes factory engineers gear the 617 engine to turn 3000 RPM at 65 MPH. That should be your target RPM for top gear.

A quick look at the gear charts and the perfect set up would be the drive train from a early US spec V8 Discovery. Find a LT77S with its LT230 from a mid '90's Disco I, grab the 3.54 R&P, order a pair of CV joint Series front axles from HEYSTEE Automotive Components (http://www.heystee-automotive.com/) (Netherlands) and you are in business with full time 4WD and Mercedes factory top gearing.

Stock Series ratios wil have you running about 700 RPM too high. Stock with 4.1:1 R&P has you running about 200 RPM too high (but is ball park enough to work if you don't mind the higher low range ratios). An Ashcroft kit in a stock drivetrain is about 300 RPM too low. The engine will be more sluggish below about 75 MPH (!).

You know I really need to add a chart for Roverdrive ratios. I just ran the numbers for a Roverdrive. A Roverdrive will put a 617 engine in the sweet spot at 65 MPH with a stock series drive train. You ARE installing 24 spline rear axles, right?

OK so you have 2 choices for best gearing for the 617 engine.

1. Stock Series drivetrain and a Roverdrive
2. Stock V8 Discovery LT77S drivetrain with CV front axles.

The LT77S is the stronger gearbox and you just have a single lever to shift. A Roverdive is your easiest & cheapest solution assuming Roverdrives are in stock.

[jp-]

Just because people can build an engine that rev's to 9 grand doesn't mean that it lives long there or gets its best fuel mileage there.

Yamaha has come out with the new R6, with a redline of 16,500. They say that driving it at that RPM is like shooting heroin into a vein. You just can't stop. I think it has Titanium rods and valves.

All I know is that I'll have one eventually. And yes, it will spend most of it's time above 12,000.

[Tim Smith]

Just because people can build an engine that rev's to 9 grand doesn't mean that it lives long there or gets its best fuel mileage there.

Yes, and reading the gauge that goes up to 6 grand means absolutely nothing about whether the motor will do it. Heck the speedo goes up to 125 in that old 300D and I think you would have to be absolutely mad to think that means the car will do it.

As a side note, I once had a FIAT X 1/9 that would cruse at about 4700 rpm to hold 60-65. It would do it all day long and did once on a 1100 mile long trip to FL. Deciding to cruse at 75-80 was more of a leap of faith in that thing...


OK, I just took pity on you.

Oh, thank god! :p


... and spent 5 minutes doing a web search for Mercedes 300TD gear ratios & stock tyre diameter then ran the numbers. The Mercedes factory engineers gear the 617 engine to turn 3000 RPM at 65 MPH. That should be your target RPM for top gear.

A quick look at the gear charts and the perfect set up would be the drive train from a early US spec V8 Discovery. Find a LT77S with its LT230 from a mid '90's Disco I, grab the 3.54 R&P, order a pair of CV joint Series front axles from HEYSTEE Automotive Components (http://www.heystee-automotive.com/) (Netherlands) and you are in business with full time 4WD and Mercedes factory top gearing.

Stock Series ratios wil have you running about 700 RPM too high. Stock with 4.1:1 R&P has you running about 200 RPM too high (but is ball park enough to work if you don't mind the higher low range ratios). An Ashcroft kit in a stock drivetrain is about 300 RPM too low. The engine will be more sluggish below about 75 MPH (!).

Thank you so much, I just get flustered when I'm trying to figure that stuff out. I guess I just haven't really sat down and though about the numbers.

As always, thanks TeriAnn!


You know I really need to add a chart for Roverdrive ratios. I just ran the numbers for a Roverdrive. A Roverdrive will put a 617 engine in the sweet spot at 65 MPH with a stock series drive train. You ARE installing 24 spline rear axles, right?

OK so you have 2 choices for best gearing for the 617 engine.

1. Stock Series drivetrain and a Roverdrive
2. Stock V8 Discovery LT77S drivetrain with CV front axles.

The LT77S is the stronger gearbox and you just have a single lever to shift. A Roverdive is your easiest & cheapest solution assuming Roverdrives are in stock.

I guess I forgot to mention... I'm running a Roverdrive right now! No wonder my previous story about NJ scared you so much. LOL

I know, I know. The brakes, steering etc... were only designed for 55 or so but when it feels right, it just feels right! :p

Thanks for all the info.

Cheers,
Tim

[graniterover]

Tim, when are you going to get going on the swap? Did you get an adaptor from Jim?

Mark

[Tim Smith]

Tim, when are you going to get going on the swap? Did you get an adaptor from Jim?

Mark

I've got to finish this house of mine first... Hopefully I'll be able to get back to the 109 at the end of the summer. The Merc 300D has it's taxes paid up till July, so I'll drive it till then and then start going over the motor to make her nice and ready for this. I'm probably not going to do a full rebuild as I don't want to over stress the series 3 gearbox I've got for this. So mostly going to check the top end, change some leaky gaskets and the like and just give it a good shine. :)

TA has been super helpful with figuring out the numbers and I think that with the rover-drive, I'll be able to use the old transmission and go easy on it for a year or two until I get a new 5 speed to throw in there.

I've talked to Jim about the adapter and got a chance to see his truck up close and personal. I have to say that I'm very impressed and will be getting an adapter once I start all this up. I'm sure I'll have lots of questions for him once this is underway.

The last adaption is for the WVO conversion. Luckily I found a guy local to me in CT as well who does these conversions with the Elsbett system. This just happens to be the system I was looking for too. He says he is ready to install at any time but I want to wait till I have the motor in the rover and all is running well before I spend the cash on that conversion. His website is: http://ctbiodzl.freeshell.org/votdi.html

I'll also have to make some kind of website of my own to document the project but that should be easy. The hard part will be removing all the expletives in my notes. :p

Cheers,
Tim