Engine Assembly Question....

[The Dan]

You need to read a bit slower and think a bit longer..... I said you need the torque plate to block the water galleries off so the water can circulate. And can you please tell me how much "flexing" in the shape of a barrel occurs when you add cylinder pressure,heat,moon cycle,wind direction and any other factors? Dont say it depends, lets use 2Bar boost on a engine with 9:1 comp, 9000 rpm, 87mm bore, 77mm stroke,30 deg timing as an example. Just an estimate is ok coz obviously there are other factors.. Im just curious

I put it in a seperate post so you wouldn't think I was talking to you. Obviously you need to read a bit slower. Calm down and take your time.

My question would be - can anyone calculate that? It would be different every power stroke.

My next question would be - does it matter and can you prove that it does?

[DVS JEZ]

You need to read a bit slower and think a bit longer..... I said you need the torque plate to block the water galleries off so the water can circulate. And can you please tell me how much "flexing" in the shape of a barrel occurs when you add cylinder pressure,heat,moon cycle,wind direction and any other factors? Dont say it depends, lets use 2Bar boost on a engine with 9:1 comp, 9000 rpm, 87mm bore, 77mm stroke,30 deg timing as an example. Just an estimate is ok coz obviously there are other factors.. Im just curious

I would say the barrel will be all farked up after the rod breaks through it or the melted piston rubs up against it.

2bar with 30degree's timing. Holy hell...

[DVS JEZ]

Do they use torque plates or anything special from factory?

[r33_racer]

Ah good ole hot honing. That is the ultimate for block machining but not many people can afford the setup to do it, usually only reserved for high end motorsport applications where they are chasing every little bit of power through improved ring seal. I'm pretty sure it was Smokey Yunick who started the development of this procedure. The idea was to do the machine work on the bores when the block was stressed and heated as closely as possible to real running conditions. Torque plate on head with heated coolant running through the plate and block at the designated temperature and pressure. Quite a lot more involved in the setup and knowledge of sizing in relation to piston to bore clearance; you need to know a great deal more to do it properly.

But all this stuff is going way off topic to what the OP had asked in relation to why his bore measurements were not making sense.

[KiwiRS4T]

Which is why I asked OP if it had been rebored or just cleaned up and honed. Need a professional such as Gerg to comment on the expected tolerance from a full rebore and machine hone!

(Too many years ago since I last had a block bored to remember)

A quick Google suggests the OP's original measurements are well within the allowed tolerance. What does the manual say?

[r33_racer]

Well he said he had gone first oversize 86.5mm. So it would have been a bore to get it close then hone to get it to size.

[britz1]

Cps manual states the bore max out of round is 0.0002" (0.005mm) ... i have mesured 0.03mm out of round witch is a fair bit out number wise but not phisically far at all ... i will bolt the head on tomoz with the old head gasket on and check it from the bottom

[KiwiRS4T]

Cps manual states the bore max out of round is 0.0002" (0.005mm) ... i have mesured 0.03mm out of round witch is a fair bit out number wise but not phisically far at all ... i will bolt the head on tomoz with the old head gasket on and check it from the bottom

OK found it in the RB Manual

Max taper should be 0.010mm which is what you found.

Max out of round should be 0.015mm (not as stringent as CP's requirement) but still you have measured more than that.

Have you called the machinist to ask them for their comments? Are the figures you came up with in line with the quality they set for themselves? And if not I guess they should fix the problem for you.

[KiwiRS4T]

And here is an interesting view from an engine builder:

>I have to wonder if the distortion form the head being bolted on

>isn't less than the normal thermal distortion form the engine

>being at operating temperature. Maybe they should bore engines at

>operating temperature too (:-)

Some people do that too - I only know of one company over here though who

advertises boring a block at running temperature. Another waste of time in my

opinion. Blocks don't run at an even temperature over the length of the bore

and the bore walls go all over the place as soon as they have high speed piston

thrust and vibration acting on them anyway.

I look at it this way. Bore wear takes place mainly in a very limited area at

the top of the ring travel. You can strip a newish engine down and find 1 thou

of wear over just a quarter of an inch of bore length but the power and

cranking pressure won't yet be much affected. That means the rings can cope

with moving in and out over that 1 thou in such a short distance. Even at 3

thou wear you see little drop in power. I stripped an engine recently with 8

thou wear and that certainly was smoking a bit but power was not too bad still.

Maybe 95% of original output.

So does even less than 1 thou of ovality or taper over the whole length of the

bore cause the rings any problems? I doubt it somehow.

I don't dispute that in theory the perfect bore should be round and straight at

operating temperature and with the stresses of the head and mains caps bolted

on. Whether the few tenths error you end up with by not boring with these

stresses in place makes the slightest difference is open to opinion. My

opinion, after seeing what engines can cope with in terms of machining error

and still run at peak power is as I say above. Also most engine reconditioners

don't get a bore anyway near round and straight at the best of times. 1 thou

taper or ovality is par for the course when I check other people's work. That 1

thou is still going to be there if they bored with a torque plate on - just in

a different part of the bore I suspect. Call me a cynic.

Dave Baker at Puma Race Engines (London - England) - specialist flow

development and engine work. .

[jet_r31]

Depends on how competent they are I guess. I use Chilton Engineering. His bores are better than perfect every time I get them back.

We've never used torque plates and never will. They are for engines that have too much flex (like windsors - lol)

I build an RB30 single cam that does mid 8's and a few 1Js that do low to flat 9's and it doesn't seem to bother them at all haha.

Maybe I'm just weird?

Lol, no ..you just know what your doing..lol,

[britz1]

Ok guys sorry it took so long but its assembled.......

there was a major problem i was havving.... my cheap dial bore guage was bot completely tight on the chast so as i spon it around in the bores it became ever so loose... after i noticed it i locktighted and then mesured again.... it was within specs

i did bolt the head on with the old gasket and torqued it down mesured the bores and they where even closer..... so in reply the torque plate makes f**k all diference for mesurment and ring gap purposes but i would say it is needed for boring(due to extra forces it produces)

[The Dan]

I would say you need a better bore gauge

[The Dan]

Ok people, so in the interest of keeping the information flowing I would like to add the following:

I did as I said I would and took the necessary measurements. The engine is a freshly machined RB26. I used a new head gasket and the same cylinder head that will be going on that block for the completed job. The measurements were taken diagonally (between head stud location) and from N, S, E and W (North, South etc) position in the bore at every 0.5-1" intervals. With the block by itself, the maximum out of round and bore taper did not exceed 0.0002" for the entire length of the bore (above where the top ring is at its highest point and below the pin boss area at its lowest).

I then fitted the gasket and the cylinder head, torqued it all down to specification using lubricant on the bolts and having everything clean etc as if it were going to be a finished job. With the head attached and measuring from the crank side down towards the valves, the maximum out of round and bore taper was unchanged from the original measurements until the final 1 inch of bore where it became 0.0005" larger diagonally and 0.0003" N, S, E and W.

This was measured using a Mitutoyo internal bore gauge.

So in summary, yes the head bolts distort the block when torqued with the head on, no it's not enough to worry about in an RB engine.

All the people using torque plates or performing hot honing, ask yourself this: If torque plates or hot honing matter that much in your RB engine, do you also bolt your sump on, attach your gearbox and bolt in the crankshaft before doing it?

All of those things should have some effect on block distortion. The question is, does any of it matter?

And to correct myself on my previous post, you might not need a new bore gauge, I read your post incorrectly the first time sorry

[Robi33]

I was under the impression that Formula 1 teams were the only engineers who could justify hot honing and so on?

[The Dan]

I was under the impression that Formula 1 teams were the only engineers who could justify hot honing and so on?

There is no doubt that in an engine that is as highly engineered as those, they would perform those practices but still, the question from my previous post still stands: when a cylinder is running, the dynamic relationship between the rings and the bore are such that any measurement you take is not going to be the same at any stage of the stroke and completely different while the engine is running under different loads because of the flex in the bore

[89CAL]

I was under the impression that Formula 1 teams were the only engineers who could justify hot honing and so on?

I think they run sleeves off the top of my head. Notto sure what they do and doubt you'd get any team to answer this

[JustinP]

I think they run sleeves off the top of my head. Notto sure what they do and doubt you'd get any team to answer this

And they certainly wouldn't be running cast iron blocks!!!

[HYPED6]

F1 also have to heat the engine up to operating temp before they crank it. Or it will seize