Engine curveball - Stroker?

[G]

I'm going to be building an engine for my 240z and I've had a curveball thrown at me - the opportunity to buy an LD28 crank for about $400. Is that an OK price?

 

The thing is, I'm going to have to buy new pistons and everything else anyway. I already have a P90 head, an F54 block (as well as a few N42 heads) and triple 45's ready to go. Given this, is the additional expense to build a stroker over an L28 limited to the additional $400 crank, or have I missed something?

 

I know that head work is where the power is, but for an L28 vs a stroker, surely the head work is essentially the same. No?

 

I don't need a monster engine with heaps of power, just something fun. However, given the opportunity to have extra useable torque I thought the extra $400 might be money well spent.

 

Am I on the wrong track here???

[Agno]

The way I see it, there is no replacement for displacement.

 

A stroker won't rev as hard as a "normal" L28 but will have a lot more torque down low. If you were just going to do the top end (head, cam, valves etc) then the cost of your build will increase as you would want to have the crank balanced/machined as well as the rods, then the pistons and then it's a slippery slope to a full on PMC engine

[NZeder]

It is my understanding that most LD28 cracks in oz go for around the $600-800 with most at the $800 point so would have thought 400 is good buying in oz. We are a bit lucky here in NZ as you can pick them up for $100-250 however they are becoming harder to find so the price is going up and mainly due having to get a complete engine.

[Riceburner]

Sounds like a good price, most I have seen are in the 500-600 range. It's a difficult question to ask as it depends on the build spec and budget. Are you using new rods with custom pistons or going with stock OEM parts?

 

Either way definitely get the the whole bottom end balanced as a unit! Including flywheel and clutch 

[G]

My plan is to have everything balanced and I'll probably go OEM spec or close to.

The engine won't see huge, sustained revs and the only people I'll be racing might be at the traffic light dragstrip..

 

 

 

 

[gav240z]

I bought mine for $800, but to be honest I'd probably go to PMC and see what he can do re: fitting an RB30 crank. I don't think they are worth the extra expense to be honest. Money is better spent on head work / valves / cam profile and triples!

 

$400 is cheap, just make sure it's in good condition.

[Riceburner]

I'd just over bore the L28, get some oversized cast pistons and slap it together with a good fully balanced bottom end. That's pretty much all my short block is.

 

You'll end up with a similar displacement, unless you were prepared to spend big bucks on custom pistons and aftermarket rods to go with the LD crank.

[peter mc]

Its funny how people think strokers don't rev , they rev as hard as any L motor , we have them at 7500 for the street engines and 8500 for race engines with 90mm stroke , and after driving the big motors you would never want to go back

[NZeder]

Its funny how people think strokers don't rev , they rev as hard as any L motor , we have them at 7500 for the street engines and 8500 for race engines with 90mm stroke , and after driving the big motors you would never want to go back

never a true word spoken. I guess most say they don't rev as they don't build them correctly - ie using heavy rods and basically truck pistons on the top - you go to a stroker for power, so do it right or don't do it at all

[gav240z]

Its funny how people think strokers don't rev , they rev as hard as any L motor , we have them at 7500 for the street engines and 8500 for race engines with 90mm stroke , and after driving the big motors you would never want to go back

 

I understand this is totally subjective to the build and combination of parts being used, but bang for buck is it really worth buying an LD28 crank at $800-$1200 AU (which is the range I've seen them fetch) as opposed to investing that money in the cylinder head, port / polish / cam set up and sticking with a std L28 crank instead?

 

I've personally been thinking of selling my LD28 crank, L14 rods and just focusing on building a good P90 head with L28 bottom end and sticking Triple Mikuni's on it, but then again I already have the LD28 so maybe I'll just use it?

 

What is the cost of fitting up an RB30 crank to an L-series block vs using and sourcing and LD28 crank? I imagine RB30 cranks are pretty cheap these days?

[G]

never a true word spoken. I guess most say they don't rev as they don't build them correctly - ie using heavy rods and basically truck pistons on the top - you go to a stroker for power, so do it right or don't do it at all

 

NZeder,

 

What's "doing it right" as far as components and work is concerned?

 

If building a motor, I would consider balancing, blading and nitriding the crank, a mildly worked head, port matching, lightened flywheel, decent ignition etc par for the course.

 

Interested in your thoughts..

[peter mc]

the thing that most get wrong is the head , strokers need more air , and port volume , and bigger carbs 48mm at min then they must have a 3in exhaust , a good stroker will be 180kw atw for a 3.1 and a good 3.4 will make 200 to 210 atw , and it will run on pump 98 easy , try getting that with a 2.8L na

[NZeder]

What Pete said....and again what Pete said once you have driven a well sorted, well built (head to match the bottom end) you will love the drive they give....hard to drive a smaller CC zed after that.

[Gordo]

What Peter said +1

I love my PMC.

[luvemfast]

What Peter said +1

I love my PMC.

Anyone with a PMC, agrees! 

 

[ZED83]

Me three, Also Love my PMC & LC stroker       

[gav240z]

Snobs ^^ LOL.

 

I guess it's true a motor is all about the right combination of parts, I just think you can also build a smaller displacement L-series on a reasonable budget and be happy with the power output.

 

Might be a silly question (as I don't have my carbs on hand to measure) but I assume Mikuni 44 carbs are named so because they are 44 mm right?

 

So the 40's are therefore only 40 mm and to get 48mm you would need webers or some other brand like OER which come in those larger sizes? I think you can get 50mm Mikuni's but they are ultra rare.

[G]

My understanding is that OER don't make 50's anymore. Biggest now is 47 new..

See here:

http://lupinusflower.ocnk.net/product/9

 

The number relates to the size of the throttle plate, i.e a 45 is 45mm.

[peter mc]

yes no more 50mm OERS but you can get 50mm webers, and if you get real cool  and have the cash 50mm solex are the best , love them ,if you can find them , expect to pay 5k for a nice set 

 

45mm carbs max out at 310hp engine on a L

 

[G]

Seen these OER 50's Peter ?

 

http://www.importmonster.com.au/view?url=http://page7.auctions.yahoo.co.jp/jp/auction/g130776785&thumb=http://auctions.c.yimg.jp/img297.auctions.yahoo.co.jp/users/6/1/5/3/ktspimcym31656421-thumb-1378444964846636.jpg&title=OER50

[NZeder]

Mikuni's 40's and 44's are a tappered bore - they are 48mm at the bell mouth down to a 40mm or 45mm butterfly - from what I can tell the bodies are almost the same with just the 40mm running a sleeve in the bore of the carb and only bored to the 40mm butterfly at the base of the carb.

 

I guess it would be possible to bore the 40 or 44 mikuni's to a 48mm never seen it done but I believe there was a place in Japan that did something to 44mm mikuni's and made them special.

 

I spotted a set of 50 mikuni's once for a good price but did not jump on them - wish I had....never mind....

[luvemfast]

I've had a look at the possibility of machining the Mikuni's while they were apart and agree that it could be done.

I also knoticed that 40 and 44 pump jets are different lengths, so assume that 50's are dfferent again.