My 505 Turbo Injection -88 project

[V-M]

I just ment, weight that set which is going in. I think its just enough to check straightness on than main axel (mine was bend). I think at Tama was not doing it for this set... I think he did with lightned flywheel ealier set.

These engines are not going to rev over 8000rpm so... I don't think main axel balancing needed.

Currently I have not found any good source... they are available but price is closely to 250€ for set.

That differential thing is very pro work... It's possible tho.

V-M

[Bean]

Don't think I'll be balancing the crank, is it really that neccessary on a straight 4-cylinder engine?

I was under the impression that it only was neccessary if you make changes to the clutch/flywheel, or if you wanted a finer tolerance.

The pistons shouldn't do any harm at least, since they aren't part of the rotating mass.

Well - they definitely are part of the rotating mass, since the counter weights on the crankshaft are in large part there to offset the rod and pistons, lightening the rods and pistons will mean those counterweights are too heavy. I would think that if you're saving ~100g on each piston and rod - you'd need to take some off the counterweight for it to balance out nice when rev'd.

Found this decent article on it: Balancing the rotating assembly

Rabin

[Johnny]

No, the pistons aren't rotating (they are reciprocating)

And I don't see how the pistons would effect the balance of the crank in a straight 4 cylinder engine.

A part of the rods are considered to be a part of the rotating mass though, usually 2/3 of the mass if I remember correctly.

As I see it, lighter pistons would only mean less bending momentum in the crank.

[Bean]

No, the pistons aren't rotating (they are reciprocating)

And I don't see how the pistons would effect the balance of the crank in a straight 4 cylinder engine.

A part of the rods are considered to be a part of the rotating mass though, usually 2/3 of the mass if I remember correctly.

As I see it, lighter pistons would only mean less bending momentum in the crank.

Yes Mr. Picky - they themselves are reciprocating - but when attached to the rotating assembly - they are by definition part of the rotating assembly.

As for balancing the crank - when you consider the weight being moved by those crank pins (rod and piston), the counter weight on the crank has to take that weight into consideration... So if you seriously lighten those loads - it makes sense that you should be able to take weight out of the crank weights too. (One could argue the pure benefit of just less rotating mass of the crank as a benefit)

I've read different articles for inline 4's and some say there's no effect - others say there is. Haven't found anything concise to explain why or why not in an inline 4, but the way I see the forces I think you'd have to...

Rabin

[Johnny]

Try my point of view

The counterweights are there to balance the weight of the crank pin and most of the rods.

Not the forces from the pistons and pins.

In a straight 4, the weight of the pistons and pins are balanced out because when one pair of pistons go up, another pair of pistons go down.

Adjusting the weight of the counter-weights when fitting a lighter/heavier piston on any engine that don't moves the reciprocating components in a similar matter would be critical though. Like a V8 or that 2-cylinder engine in the article.

[Bean]

Yep - I've already taken into acount the pistons moving on the same plane and not needing the same kind of balancing of other engines, but you will be decreasing the weight that's being swung by those crank pins, so that has to affect the size of the crank weights too.

But you said it yourself best: The counterweights are there to balance the weight of the crank pin and most of the rods. Since you're cutting the rod weight so drastically (~20%) - that's going to affect the crank for sure - especially at high rpm.

And while there are balanced forces of the pistons (going up and down cancelling each other) that total force being generated (just from the drop in weight) is going to be a fair bit less with lighter components, so it makes more sense to take advantage of that and take some weight out of the crank counter weights as well... It wouldn't be necessary to trim extra weight off - but if balancing is being done anyway because of the rods, then some knife edging or profiling wouldn't hurt...

Rabin

[Johnny]

Yes, I know that lighter rods is affecting the balance of the crank. 20% lighter sounds a bit much, it will be closer to 10% actually.

The question is what this will cause in the real world.

But we were not discussing the rods, and I'm still not convinced that the weight of the pistons will affect the balance of the crank or why.

[Bean]

Yes, I know that lighter rods is affecting the balance of the crank. 20% lighter sounds a bit much, it will be closer to 10% actually.

The question is what this will cause in the real world.

But we were not discussing the rods, and I'm still not convinced that the weight of the pistons will affect the balance of the crank or why.

You sure like splitting hairs... If you re-read my post - I mentioned them together since they are both being lightened. Technically only the rod will affect the balance of the crank. (I was assuming IF significant drop in piston weight existed.) I was initially theorizing that the weight of the pistons should come into play with the crank weights - but after discussing and reading up more - I was thinking of the forces created when running, and not purely as a rotating assembly.

That being said though - If there's less piston mass being moved by the crank - you should be able to optimise the crank weight a bit as well since it won't be seeing the same loads. (IE knife edging the weights)

It's totally un-necessary for a regular build - but previous posts you had inquired about raising the rpm limit and such - so I thought you wanted to really max out the motor build.

I'm going to building up mine very slowly - so I will be spending the money on such things, as I do want the motor to be able to pull 7000 - 7500 RPM if necessary.

Rabin

[Justice]

I agree it would be stupid not to balance the entire drive train when you got it dis-assembled. Especially if you want to run those vtec like rpms.

I'd put it on a dyno when you are finished though. No sense in going up that high if your power starts dropping in the high rpm range.

Stock rpm redline on the turbo is 6k or something?

[Metako]

I once rebuilt a 504 motor and weighed the std pistons that came out - there was a 10 gram difference between the heaviest and lightest piston! So I removed weight from the pistons to bring it down to 1 gram difference with no other changes to crank, rods etc and the difference was amazing. It reved much more easily and smoothly. Couldnt believe the factory could fit pistons with a 10 gram difference (unless it had been rebuilt by someone else).

[Johnny]

Rabin,

Splitting hairs or not, I thought you were still talking about balance.

I get your point but I don't think I'll be putting money on knife-profiling. It feels like that money could be used better elsewhere. (like a larger turbo )

Justice,

I think its stupid to spend money on something that might not be totally neccessary. Of course it would be better, but this is kind of a budget build.

If you need a dyno to know when an engine looses power, then I think something is wrong with the drivers butt.

And hopefully I'll be getting that info from datalogging MS anyway.

As far as I know, the rpm-limit should be 6500rpm.

Metako,

Interesting, my belief is that for the smoothness of the engine, it's more important to have the pistons and rods to equal weight/balance than balancing the crank itself.

It would be interesting what the tolerances for the rods and pistons were in the N9Txx when they put it together. Weighing my pistons won't be any good

You could probably have got an even smoother running engine if you had balanced the rods too.

[Justice]

Justice,

I think its stupid to spend money on something that might not be totally neccessary. Of course it would be better, but this is kind of a budget build.

If you need a dyno to know when an engine looses power, then I think something is wrong with the drivers butt.

And hopefully I'll be getting that info from datalogging MS anyway.

As far as I know, the rpm-limit should be 6500rpm.

I must have missed the budged build part of it all. Anyway, you could program the fuel cut to 7500, but if you are not balancing everything I'd keep it stock. Rotational mass is going to blow up any weight. It's like a fighter pilot in a steep turn. 100kg becomes 700kg.

Sides, if you keep a small turbo, it's going to boost early. A bigger turbo would benefit from a higher limit though.

[Johnny]

Well, I haven't said straight out that it is a budget project but I am a poor student.

Is this big enough to benefit from a higher rpm-limit?

[Johnny]

It was a while since I updated now, but I'm making some progress.

The block has been honed to accept the volvo pistons, and I will also deck it just to make sure it's perfectly straight. I've bought a 200mm indexable face mill to do that job (and also the head later), had to make my own adapter to fit it to the milling machine at the university.

I'm thinking about o-ringing the block also, it shouldn't be so hard to make a tool for that...

The pistons are pretty much done, I machined away about 2.5mm on the top and made the pit a bit larger so I should have 8:1 compression ratio and the same pin height as the OEM pistons.

Rod bearings and piston rings have also been bought.

Now I just have to make some spacers to go between the pistons and rods and some kind of baffle for the oil pan and my bottom end should be ready to go.

I'm a bit concerned with the main bearings though... I wasn't planning on replacing them since they're so damn expensive, but they aren't as pretty as I'd hoped so I don't really know what to do.

Btw, the turbo in my last post is a holset HX35, intended for this engine.

[V-M]

What size bearings u need?

V-M

[Johnny]

STD size

[Johnny]

Here are some pictures of the resurfacing of the block that I did today.

The pictures are of a test-block, but I have resurfaced the actual block I'll be using too.

This may be overkill but I also cleaned up some roughness in the casting.

Here are some pictures of the facemill and the adapter.

[V-M]

STD size

Ah... sorry. As said earlier... I have only 0.1mm sets and bigger oversizes.

V-M

[Johnny]

Getting closer...

Status:

* Rings gapped

* Rods weight adjusted to within 1 gram

* Pistons + rings + spacers + pin weight adjusted to within 1 gram

* Head welded and resurfaced.

* Bottom end reassembled

* Head gasket and front seal ordered

* Made the rest of the gaskets

Started with some cleanup of the ports of the head, I will probably regrind the seats and valves for some extra low lift flow also. I'll do a more serious porting later since I don't have a flow bench to measure my results with yet.

So the lion will roar this summer! I've bought a spare chrysler-simca head which is practicly new (less than 59000 km), so I have a backup in case something happens to the head I have.

My goal is to get it started next week.

[norcal505]

great to hear johnny!

[Johnny]

Going slower then I had hoped , half way through some mild porting though.

Std

Ported, not completely done, it still needs some smoothin of the rough spots with sand rolls and some finishing with my double flap wheel (picture of it below). This is my first attempt to port a head, but I hope I haven't made it worse. I also smoothed out the combustion chamber of sharp edges.

And here you can see my world class "workshop" (tiny garage) and arsenal of porting tools

The valve seats have been resurfaced with a 45 degree Neway cutter.

I managed to borrow a valve grinding machine also so I grinded the valves too.

And here they are, three angles 44,30 and 23. (look hard for those angles, haha)

And the machine who did it

Here are some pictures of the bottom end

That's right, homemade degree wheel, (I told you I was cheap, and it was the fastest way of getting one ) Here's the link so you can make your own if you want Free degree wheel

And here's some bonus pictures of an old motorcycle my dad renovated many years ago.

[V-M]

Don't think I'll be balancing the crank, is it really that neccessary on a straight 4-cylinder engine?

I was under the impression that it only was neccessary if you make changes to the clutch/flywheel, or if you wanted a finer tolerance.

The pistons shouldn't do any harm at least, since they aren't part of the rotating mass.

Hehe, that thought came to my mind too.

I will balance/weigh the rods and pistons.

Did you mean between the old set of pistons and rods and the new, or 5g difference between the rods and pistons in the set I'll install?

Did Tama balance his crank? (Because of the rods/pistons)

That's a shame... any idea of where I can get bearings for a reasonable price?

Do you know if I could swap the gear set in the open diff with those in the lsd?

Only straightness is needed to check. IMHO All 4 axels which I have re-used were bend and needed to be straighten before milling.

I ment between new set pistons and rods First balance pistons then rods. Then combine weigts to match.

I think he did crank and flywheel... I'm not sure. But I think he did some lightening for flywheel... have to call him and check.

I have not find any other than simon-auto.de for source... and there price is 260e/set.

I think you can swap.... but measure tooth hitting from old setup to compare after re install.

V-M

[Johnny]

Ok, that was what I hoped you ment.

I weighed the rods and pistons(+ pin and guide-shims) to within 1 gram, seperatly and together. The crank wasn't checked for straightness, but it rotated smoothly with the bearings mounted so I hope it'll be alright.

Cool if I could swap the differential gears! But I'll use it as it is first and maybe swap the gears over some winter in the future since it'll probably take some time to do it right.

Here are some pictures of the finished intake port.

And here's a comparison of the stock and ported short radius, which I'm very pleased with

Any comments on the progress?

[V-M]

I would shorten that inlet guide and make it also bit narrover.

In my next re-make head I'll cut that totally off

V-M

[Bean]

Very nice Johnny - that inside radius looks perfect!

For max performance I agree with V-M - you could likely lose the valve guide protruding, but if nervous you could always shape to a tear or oval shape...

Very nice work though - be curious to see how it runs once all together!

Rabin