Big engine: any downsides?

[SiDev]

So, I'm toying with the idea of a bigger motor, something for all-round power and torque but still reliable. I've heard lots of good about big engines, but are there any downsides like reliability, weakness, etc?

 

[StuF]

I think it's often all the other issues bigger engines can create that puts me off

Engine being more powerful usually needs a higher geared box to transmit it and manage the input without exploding - rancho/freeway flyers aren't cheap

Then with all that power and speed you need better brakes to carefully and safely slow you down which could mean installing a servo and (another) bigger aftermarket brake kit.

Then ancillaries such as driveshafts and standard mounts may be stressed more than their design specs and may need uprating.

Think it could be a never ending list of upgrades depending on how much power you go for.

All that said - never say never!

 

[Resto-raider]

A bigger engine doesn't right away have to make 150Bhp.
You can also get a bigger engine with say 80Bhp and you won't have to change all that stuff.

Personally i never understood why a bigger engine means upgrading your brakes. Going 65mph with 50Bhp is the same as going 65Mph with 150Bhp. These vans aren't exactly made to go fast.

 

[StuF]

Personally i never understood why a bigger engine means upgrading your brakes. Going 65mph with 50Bhp is the same as going 65Mph with 150Bhp. These vans aren't exactly made to go fast.

I agree but whats the point of a bigger more powerful engine if you aren't going to drive faster and accelerate harder (where permitted) - therefore more braking is required as the speeds in reality will be higher. And yes these vans weren't made to go fast - but they still can when fitted with a 2309/2500 and so on! If you have the power to drive forward quickly surely it makes sense to be able to rein in that power effectively and safely?

Traffic light goes to green - you accelerate hard away in your big engined bus
Mr Vectra pulls out of a side street not wanting to be behind Mr old in his knackered bus - not realising you are doing 40mph
Big brakes safely scrub the speed off and you carry on

Standard drums might have a different outcome unless they are in tip top condition and perfectly adjusted
Bigger engine to me equals more power, more acceleration, higher cruising speeds and more frequent trips to the petrol station!

 

[wolfgang]

1776cc is not a massive upgrade in size and cost but is a good bigger engine for a type 2.

 

[Trikky2]

Personally i never understood why a bigger engine means upgrading your brakes. Going 65mph with 50Bhp is the same as going 65Mph with 150Bhp. These vans aren't exactly made to go fast.

I agree but whats the point of a bigger more powerful engine if you aren't going to drive faster and accelerate harder (where permitted) - therefore more braking is required as the speeds in reality will be higher. And yes these vans weren't made to go fast - but they still can when fitted with a 2309/2500 and so on! If you have the power to drive forward quickly surely it makes sense to be able to rein in that power effectively and safely?

Traffic light goes to green - you accelerate hard away in your big engined bus
Mr Vectra pulls out of a side street not wanting to be behind Mr old in his knackered bus - not realising you are doing 40mph
Big brakes safely scrub the speed off and you carry on

Standard drums might have a different outcome unless they are in tip top condition and perfectly adjusted
Bigger engine to me equals more power, more acceleration, higher cruising speeds and more frequent trips to the petrol station!

If your brakes can lock up the wheels then bigger ones will not change that. A servo means you will be able to lock them up with less pedal pressure. Bigger brakes are fitted primarily to cope with heavy repeated use to avoid overheating and its consequent fading.

If your brakes can't lock up the wheels then get them fixed.

I have servo disks btw because it makes it nicer to drive with less effort.

 

[Resto-raider]

I have a 1776cc engine in my bay since last year. Allthough it is faster off the line I don't really use it to drive fast or drive at higher speeds than I did before. I upgraded the engine because I wanted to make it up the hills when driving in France and Spain and so the engine wouldn't have to work so hard when accelerating in modern traffic. I built it with torque in mind, not speed.

I do get your point Stuf, but people pulling out in front of you will always be an issue. With or without a bigger engine.

So if you don´t want lots of other upgrades go with the 1776cc.

 

[Trikky2]

1776cc is not a massive upgrade in size and cost but is a good bigger engine for a type 2.

Agreed. A well built 1776 is a great upgrade and will be just as reliable as a stock engine. Just build it for torque, which is what you need in a bus.

Down sides? Well I built myself a considerably bigger engine coupled to a six rib box. Sure it's quick and fun - but if I am honest it's way more than I need and over geared.

If I were doing it again I would go for the 1776 option, with a 5 rib box or simply larger than stock rear tyres to give longer gearing.

Engine mounts are not an issue unless you go drag racing. A stock clutch can cope with a 1776 but if you go over 100bhp then a stage 1, like a Kennedy, is recommended.

In normal touring the mpg is actually slightly better than stock due to better flow and higher compression. This is quite common. There's a few cars being sold new today that have the same inconsistency ie. The larger engined version actually gives better mpg because it's less stressed in normal driving. Thrash it and use all the power then of course the mpg will suffer.

Main downside for me, apart from the wallet bashing build costs, is the noise. The more powerful engines need a better flowing exhaust and they make more noise than a stock engine.

 

[Marriedblonde]

I'm watching this thread with interest.

I have a 2187 lump in the back of my bus and I love it. Mated to a standard 3 rib box at the minute makes for a very entertaining driving experience.

I will be changing the gear box in the near future but I was desperate to get it back on the road and with larger rear tyres it cruises happily at 65/70 mph.

I have got bigger brakes, drums as ***** regardless of what people say, they over heat really really quickly and are not up to the job of slowing down a loaded bus full of people and a weeks camping equipment. Let alone capable of slowing down a bus multiple times.

Why did I go for a big lump? Simple I wanted a bus that could keep up with modern traffic even when loaded up and also to tow a trailer for holidays away.

It is better on fuel than the previous 1600sp I had in the bus so long as you don't keep the taps wide open and jesus it flies now. You can cruise down the motorway without worrying about the hills and down in devon it came in to its own. Pulling happily up even the steepest of hills without nay problems at all.

 

[SiDev]

Good feedback boys, cheers. I put a new 1641 with twin 36 Dells in last year and it's fine, got around 75bhp on the rolling road and over 80lb of torque from memory. It goes ok, a noticeable improvement over stock, but I'd like more grunt. I put 2ltr type 4 motors in my last 2 buses and these seemed to have more grunt through the range. The rationale for going big is that if I'm going to the trouble of having the block machined, I may as well have a bit more cc. Undecided.....

 

[gas1man]

Not to hijack the thread but can you get away with a single carb on a 1776, or do you have to have twins?
I do realise that the power and mpg will be better.

J & P

 

[Resto-raider]

I have a single carb on my 1776cc engine. It works just fine. Some renowned German engine builders swear it's the best setup with the single carb.
I did bore the 34pict3 carb to 39. But even with a stock carb and the right jets it will work

 

[gas1man]

Thank you very much.

J & P

 

[toffo24]

Hi Si
Well I in the big engine boat and all I can say is it's great to have the hill climb and overtaking power , downsides are you would need to strengthen the clutch and upgrade the brakes. Also be prepared for some additional cooling as this would help if you ran a taller geared box.

Really pleased with the 1904cc engine that I run but I have had a few issues so it's not been all plain sailing but worth the faffing about as its a better van now. Hope they s helps and pop up if you want to have a ride out.

Pete

 

[K@rlos]

I have a 2110 and will never look back! Gets to and sits at 70 effortlessly and is more economical than a 1600 because I don't have to ring its neck everywhere. The massive amounts of torque make it a pleasure to drive and the big HP makes it fun blasting off traffic lights and leaving GTI's and BMW's for dead :mrgreen:

All depends what you want from the engine, if your not tight with parts and get it built properly it shouldn't create an issue that a stock motor would suffer from. Mines in bits atm but only because of a stuck oil pressure plunger which happens to stockers too...

 

[easy]

I personally like a 2110, but i would twin that with a decent gearbox. Personally if its just a bit more beans, try getting some decent twin cards such as 34icts or some 40 idfs and you will add that extra power when you need it. The 34s wont hurt you petrol bill either! the 40s will make a dent. Both wont cost anywhere near a new engine price :mrgreen:

 

[creationblue]

My two peneth, a 1776 with twin 40s will get you around 90hp, mine is mated to a 6rib box and the gearing is rubbish for me. It really depends how big your family is, whether you pull a trailer or not. If it's just the two of you then this set up would be a really great combo. Add 3 growing children, and a dog, then a trailer and I find that the engine needs a gear between 2 and 3. I've just returned from a 1500mile tour of Scotland and apart from the gear issue the power of engine was adequate for all but the steepest of mountain passes. Of course it also depends on if you use your bus for long distance driving or just potter about to local shows, a big motor will cost big money.....

You could consider a Subaru motor if you want a modern fuel injected engine that is capable of high speed and high miles all for the cost of a few hundred pounds for the doner, and a bit more for the conversion parts.

 

[Supertramp]

5000 miles into a European/Moroccan road trip on a virtually stock 1600 with twin carbs and I honestly can't see why I'd need a bigger engine. If I wanted to sit at 70mph I could, but I drive a bus so getting places quickly isn't a priority.
It's got me up and over the pyrenees and Atlas Mountains. Never unable to keep up with traffic. 25mpg and no issues thus far.

Not sure a 1776 or 2L+ would do anything for me

 

[lids_2001]

78 x 90.5 is the best combination in a bus imho. Provides the torque needed for hills and the bhp to accelerate. Use twin 40s and it will go on and on. Keep the CR down and you won't see it get too hot. Gene berg wrote an article about using stock carb in this size engine, I will see if I can find it.


Sent from my iPhone using Tapatalk

 

[Earl Bay]

Why would you favour 90.5 P&C's if you can get thickwall 92s? Shouldn't the 92s suit a bus better because of the heat issue? (besides the increase in cc's)
I'm planning a build over the winter: something around the 2110 mark. Not sure on the combo yet. 90.5 or 92s. 78mm or 82mm crank.
But definitely a single carb setup because I want and need it to look as stock as possible.

@ resto-raider: Shool me on that single 39. I'm considering it. Do you have any experience with the stock carb on that same engine?
How much more HP do you gain with the 39 over the stock one? And how much more fuel do you need with it. From what I've heard not everybody
can justify the 500€ for a 37 or 39 carb. It sounded like you don't gain more than 10HP but 1-2 liters more in fuel per 100km. So, do you think it really makes that much of a difference?