LVH 1911 Specification and Performance Review

Discussion in 'Modified Shizzle' started by Owen Snell, Aug 27, 2014.

  1. Specification first. @Paul Weeding took my very worn 1700 Type 4 and did a full refurb on it as follows:

    Keeping the original stroke, the case was line bored and the crank reground.
    1800 heads polished and ported with new valves and guides.
    Eurorace II cam.
    96 mm barrels and pistons to raise the capacity to 1,911 cc.
    Twin Weber DCNF 40s + K&N filters (used, supplied by me).

    400 miles after rebuild, this gave 102 BHP (corrected at engine) at 5,000 rpm. The power and torque curves were quite steep with not a lot going on at the lower end of the rev range!

    I ran in this configuration for about 6 months and 2,000 miles. The good point was strong acceleration especially if revved a bit, but fuel consumption was a disappointing 18 mpg, it tended to run hot (115 degrees when cruising gently in cool weather) and wasn't happy at less than 2,000 rpm. I also had a strong smell of petrol from the vents, suspected to be the carbs.

    With a few oil leaks as well as the oil temperature, the van went back to Paul. He sorted out the leaks and installed a secondary oil cooler in a scoop under the van. To go with the extra length of cooler pipework, he also uprated the oil pump to 30 mm (from standard 26 mm). The carbs were rebuilt to solve the petrol leaks.

    At the same time, I got a used gearbox refurbished with a longer (2 litre) final drive and longer 4th gear as cruising speed was very noisy with the original ratio giving around 16 mph / 1000 rpm in top.

    The new setup has not been in that long, but with a trip to Italy thrown in, it has covered over 2,000 miles in not much over a month.

    Performance: Even with the longer box, the engine pulls 65 mph easily on a hill and was only a problem on some of the long steep hills we encountered in the Alps this summer, especially as the performance did drop off a bit at high altitudes. The big issue is that if forced to slow down due to other traffic, it can be a struggle to get back up to speed on steep hills due to the lack of bottom end torque. This was 5 up with luggage.

    Gearing: Although the gearing makes the 3rd - 4th gap quite big, it has made a huge improvement in noise when cruising, raising the ratio to around 20 mph / 1000 revs.

    Fuel consumption: Sorting out the leaky carbs and raising the gear ratio has improved the fuel consumption to an average of nearly 24 mpg over an 1,850 mile trip with multiple large climbs and at a cruising speed of 65 mph.

    Oil cooler: The additional oil cooler means that the temperature now sits at around 90 degrees cruising at 65 mph. Long uphill spells raised this to 100 degrees and I saw just over 110 degrees on a few occasions on steep climbs at high altitude when the engine was really working hard.

    Drawbacks: The engine does not pull well below 2,000 rpm, but that's hardly surprising for a short stroke motor in this state of tune. Adding the longer ratio box has shown this up even more and any future improvements will be directed at this area. I'm not convinced that the rolling road set up was a great job and maybe a better state of tune would help.
    Last edited: Aug 27, 2014
    Dicky, Paul Weeding and paradox like this.
  2. Nice honest and proper review:thumbsup:
    Owen Snell likes this.
  3. I'm really pleased with the engine and thought that I was taking a chance putting a long ratio box onto a tuned short stroke motor, but it has worked out well. Now to see if some setup work can improve low rev pickup, although the engine was built from the start to be expandable with a stroker crank, so that's an option as well.
  4. Id imagine paul has done your heads ready for the future upgrades we all think about when were telling a builder our dream list:thumbsup:

    Ill wait for paul to comment as hes the one who built it and he has his own reasons and your build spec to work with:thumbsup:
    Im hoping paul will say if you want to increase the bottom end pull then restrict the intake to a degree:thinking:
    If not then im looking forward to some free education as to why not

    Im not knocking paul i just love the answers that come out of these sort of posts
    I have built a few engines in my time but never an aircooled engine
  5. Im thinking smaller chokes as im guessing they are a bit big. But what do I know... Tbh less was more with my bus and it went from top end revvy to some resonable torque and driveability when I went down a couple of mm.

    Good write up. Thanks.
    paradox likes this.
  6. Just dawned on me 102 bhp @5000rpm!!!! thats revving some - was that peak power?
  7. 66mm crank, so they can rev to 5400rpm :thumbsup:

    My 2270 revs to 7000rpm :lol:

    You could try dropping in a size down on the chokes, but it would also knock the top end... bit of a trade off...

    Options would be:
    Stroked crank to increase capacity... It would involve changing the pistons as the wrist pin height has to move...
    EFI - This would give you a better tune over the rev range of the engine!!
    Ignition system - A bigger spark, or multi-spark system would give better throttle response, as the fuel would ignite/burn better.
    Cam shaft change - A cam with a little less duration and lift would drop the torque curve down the rpm range
    Exhaust - We're working on this - but a better flowing system can increase torque, and top end power.

  8. If it revs to 5k on a 2 litre box then I think that the sacrifice in top end would only be an issue through the gears but Im guessing theres plenty to trade. Mine runs out of puff at around 60 (on the clock that is) in third with the 30s but with the 32s in there it was more a case of me changing up before I blew it. There was that much difference!

    Ive not much experience really but revvy type 4s feel right tbh its just getting the mix right with the torque I suppose but a fully loaded bus with 4 people and camping gear is a different proposition to just driving it on your own!
    Joker and Paul Weeding like this.
  9. Nice write up Owen :thumbsup: Have you considered a tuning session on a 'proper' rolling road? That way they can plot the kind of torque curve you want and set it up accordingly. As @Dicky says you're probably wanting to trade off some of the top end to get real world useable torque. Sounds like you've gone the right way with the gearbox I guess the question is though how much time is spent driving in 4th gear at +60mph? Get the lower end torque sorted out and sounds like you'll have the perfect set-up
  10. I was driving along the autobahn thinking about EFI. I think it's a fueling issue as it just gets really fluffy below 2k revs and much easier to balance top and bottom end with the control you get from EFI than from a carb system.

    It does seem sensitive to anything not completely tight on the coil connections, so timing and spark quality do matter. Running an Accuspark dizzy at the moment which was a huge improvement over old one that didn't advance enough. Are the 123 dizzys really much better?

    This and the stroker crank are further down the line!
    Paul Weeding likes this.
  11. You definitely feel it more with the longer box, but the cruising comfort is so much better at lower revs. The torque curve is so steep, 2,500 - 3,000 rpm is a long way down from peak and if you change up from 3rd going up a big hill, it doesn't want to pull back into the torque range where it can run in 4th. It's only bigger hills and we were heavily loaded.
  12. I suspect the rolling road who did the initial "setup" didn't really try and optimise it, just did a power run and checked the jetting was OK. A "proper" rolling road would do more than that and I think that I would notice the difference.
    Indicated 65 mph is a nice cruising speed, I'd just like to be able to recover that speed on a hill if interrupted by slow traffic, rather than ending up stuck in 3rd.
  13. I have no idea what venturis are in there at the moment, would be nice to find a rolling road with the expertise to balance out all of these variables, not just do the simple stuff.
  14. Sounds to me like the vents are too big from your descriptions its sound extremely familiar to me.
    Owen Snell likes this.
  15. I can't remember what is in them either... :eek:

    As for the spark, this is something I had to address on my engine with cold starts and no choke.... I'd already got the mallory unilite dizzy, so i put on the matching high output coil, and instantly I could cold start without multiple stalls of the engine...

    You could also install a wideband lambda LM1 system, and that'll tell you exactly what the fuelling is doing across the rev range :thumbsup:
  16. The Mallory dizzy is mechanical and out of stock according to their site. Do they do an electronic one?
  17. I did mine on a rolling road in a race car builders. They run F3 cars and Britcar so build their own cars and develop engines and stuff. They really know what they're doing and as they have a rolling road setup in house they rent it out as well as other services to Motorsport. As a result they really know their stuff. They did a cracking job on mine when I put it on the road, the caveat was I had to ensure the valve clearances were spot on as they didn't want to do that in house due to time and not having an available lift. They spent time doing the jets, mine are dells and they installed replacement jets and drilled out the ones that needed to be bigger. As they went they fine tuned it all so that it had the right balance of torque v rpm; if you're only ever going to drive on flat roads having bags of torque isn't critical but we live in the real world. If you can get yourself to Hereford I'd highly recommend them. Takes about 2 hours
    Owen Snell likes this.
  18. Good point on the valve clearances, thanks.

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