Steel crank

[Europa88]

I'm thinking of building a steel bottom end for my current 701m block, to release some power at higher revs. QED in the UK do an EN19b crank and a fully counterweighted EN40B crank. I'm not racing, but doing occasional track days and plan to take the engine to 8K RPM only in short bursts. Would any one know if the EN19b crank is able to accommodate these requirements?

[2cams70]

The fully counterweighted crank will have less internal stresses at high RPM and the engine itself may operate a bit smoother. The disadvantage is that it may be heavier and as a consequence the engine may not be as responsive as it would be with a crank that isn’t fully counter weighted. Either will be ok though. Good choice to do this rather than go the long stroke / big capacity route that most people seem to follow.

[rgh0]

Dont know the limit of the EN19 crank but QED should be able to tell you, after all they sell it. Someone here previously reported they use this crank to 7900 rpm. I have no personal experience with it.

cheers
Rohan

[Europa88]

Thanks guys.
I have been dealing with QED for over 30years, but now it seems they are just sales people since the machine shop closed. I will ring them to see, as they market this EN19B crank for clubman racing and I'm not going to race it even.

[ill_will]

In my notes I have that QED's long stroke EN19b crank is ok for 8000rpm (I have one, but the engine is not finished yet) but worth confirming with them.

[StressCraxx]

I have an EN19b in my 23b. They are indeed good to 8K. The other areas of concern are the piston ring lands and the valve train when you spin a twink to 8K. Time between overhaul, particularly the valve train is halved when you go from 7K to 8K. Speed costs money.

[Europa88]

Just to help any one else, this is QED's response to my Question on their steel cranks.

Good morning Neil,

The rev limit on an EN19B is approximately 7,500 - 8000 and the rev limit on the EN40B is approximatlely 9,000.

The approximate weight of a EN19B crankshaft ( SKU 106001 ) is 13.04 kg

Tha approximate weight of an EN40B crankshaft ( SKU 106004 ) is 12.1 kg

Regards

Calven Bayliss
Parts assistant
QED Motorsport Ltd

[2cams70]

Interesting - thanks for posting. The fully counterweighted crankshaft is actually lighter. I used the QED EN40B crank my engine but either is going to be ok for what you are using it for.

[Europa88]

Any one know the RPM limit on the cast jackshaft. Should I replace it with a steel one or can you get short steel jackshafts?

Any other words of advice on building a high RPM TC?
Steel sprockets or verniers?
I will be keeping the L14's and going steel followers for now.

[rgh0]

I presume you have read my writings posted on building modified twin cams ? Happy to expand upon areas that need further explaination.

Shortened steel jack shafts are avaiable. i have used both shortened steel and cast iron jack shafts at 9000 rpm without issues

cheers
Rohan

[Europa88]

Thanks Rohan.
Yes your pdf's are exceptionally useful and I have spent many hours reading them. Its just little things that make me go hmmm? Like the cam sprockets. Mech fuel pump ( I'm guessing I'm going to have to go electric with a regulator for Dellortos) I wont be going much (If at all) over 8000RPM so I may shorten the original cast iron jackshaft. Do I need steel crank pulley and what size? Do I need to uprate the oil pump? I will still use this car on the road, but it is no way a daily driver.

[2cams70]

Whether you use a steel or cast jackshaft is more to do with the type of gear you run on the oil pump than the RPMs you are doing. I’d recommend you just use the standard jackshaft - shortened if you wish to but not essential. Cast iron shaft works best with the original cast iron oil pump drive gear. Most of the aftermarket shafts have a continuous circumferential oil groove in the front journal (like was standard on the BDA) rather than the 4 slots of the original shaft. I prefer the original style. The BDA had an oil restrictor in the block as standard. The LTC did not. Best to bump up the oil pressure a bit to 55/60 psi if you are extending the RPM range. You’ll need square mains caps and should consider uprated conrods. Fitting a steel crank is just one thing when you increase the RPM range. There’s a whole lot of connected things that need to be considered. If you fit just a steel crank, square main caps and uprated conrod bolts you’ll probably only upgrade the continuous safe RPM limit to 7K without doing more.

[rgh0]

Thanks Rohan.
Yes your pdf's are exceptionally useful and I have spent many hours reading them. Its just little things that make me go hmmm? Like the cam sprockets. Mech fuel pump ( I'm guessing I'm going to have to go electric with a regulator for Dellortos) I wont be going much (If at all) over 8000RPM so I may shorten the original cast iron jackshaft. Do I need steel crank pulley and what size? Do I need to uprate the oil pump? I will still use this car on the road, but it is no way a daily driver.

I am yet to write the chapter on ancilliary items to consider which will further address some of your questions but a couple of comments below.

1. The standard cam ( edit : meant cam not crank) sprockets will be fine for the RPM but you will need to use offset dowels to get the timing accurate to get the best out of you cams. I did that for many years but in the last few years i have changed to using adjustable cam sprockets as its quicker and easier to set up the timing. If using offset dowels leave the sump off while doing the timing so if you drop a dowel while changing it you can recover it from the floor and not have it left in the sump !

2. The standard fuel pump will work in most circumstances especially if only using full 8000rpm power for short periods on the road. Electric pumps are great for starting a car that is not used every day as they fill the carb bowls without excessive cranking. I found that long full throttle runs on the race track could lead to low fuel levels in carbs and misfiring and I now use a high capacity pump and larger fuel line and pressure regulator but this situation never occured on the road or most race tracks just the long run uphill along the back straight at the Sandown circuit i racfe on.

3. The 4 inch standard diameter cast iron crank pulleys are OK for road use at 8000 rpm. If you pulley is at all damaged as they typically are where a chip is taken out of the thin rear face when being removed then i would replace it with a steel one. I would use a 4 inch pulley for a road car where you will only see the full rpm occasionaly for short periods and where you need to alternator and water pump working well at lower rpms most of the time.

4. A shortened orginal cast iron jackshaft will be fine. I see no difference in reliability performance of the steel or shortened cast iron and I have used both. The continuous feed groove versus the orifinal machined slots appears to make no difference if the cam bearing are in good condition in terms of oil in the head. I have never needed to use an oil restrictor with either type of jack shaft.

5. It is hard to be definitive on what oil pump to use. I have always been conservative and used a high volume / high pressure pump. is high rpm engines. This ensures sufficient oil flow to cool the bearing at high rpm. I know people who successfuly use standard volume / high pressure pumps in race engines. This reduces power losses a little and redcues actual flow through the bearings only by a little and appears to work OK. A standard volume / standard pressure pump could be used probably for road use with limited 8000 rpm operation but i would not recommend it. One advantage of the high volume pump is better oil pressure at idle when the engine is hot after a prolonged period of high RPM operation such as when you come into the pits after a race.

cheers
Rohan

[2cams70]

The fuel pump you need and fuel flow rate you need is in direct relationship to the engine power output. I have never seen this data for the standard ac pump. I’ve never seen the ac pump used in a high performance/RPM application. Personally I wouldn’t trust it. If the pump lever arm started bouncing on it’s cam lobe at high RPM the result might be nasty.

[Europa88]

Thanks for the comprehensive replies.This is going to be my winter project, one I’ve been wanting to do for years!
Cheers Neil