1600 Stroker motor build....

If your going to stick with 86.4 bore size, and not re bore the block...I can sell you a set of 34.9CH small flycut pistons (used) that I removed from a core engine (Regata 85s engine) that I stroked to 1599...

$10 each plus postage...

you'll need to buy rings, and have the flycuts (handed ie, 2 left pocket and 2 right pocket so the inlet flycut only) enlarged to suit your BVH ... but this will get your 1500 over 10.5:1 ...

you'll have about .3 to .4mm of pop up, so with a 1.55 crushed (felpro) you SQ will be about 1.2 to 1.25...that's getting very close to the optimum value you want.

then your 40/80 cam will start looking like a good choice.

I crunch numbers like this on a daily basis, so no problem doing the math... it's very easy for me.

Summing up... if your not going to get above 10:1...don't bother stroking the engine to 1600 ...as we just confirmed, you static CR will be higher with pistons that are easier and cheaper to find if you stick with a 1500.

And you NEED to get that static CR up over 10:1 (absolute minimum I would prefer about 10.5ish) if you want your cam and carbs to work well... if you go 1600 or 1500 that fact doesn't change

SteveC
 
I'll take the pistons!!!!

PM me the total and where to send the money via Paypal.

Absolutely, that would be amazing. Do you happen to know if the Fel-pro head gasket squishes is the same as this one:

This one:
http://www.ebay.com/itm/Fel-Pro-21195PT2-Head-Gasket-/350627115011?pt=Motors_Car_Truck_Parts_Accessories&fits=Make%3AFiat|Model%3AX-1%2F9&hash=item51a3013003&vxp=mtr

I ordered a "Fiat" OEM head gasket from Midwest that needs to arrive yet which claims to crush to 1.1-1.3mm according to Matt, do you recomend the Fel-pro over OEM "Fiat" head gaskets.

I believe the OEM head gaskets need to be re-torqued at 500miles which is fine. I have been really pleased with the Fel-pro product though.

'PeteX1/9
 
Actually what I meant

...was not the flycut diameter, but the depth.
After I built my engine, my valves bottomed out in the valve flycuts ever so slightly.
They come real close still, which keeps me from installing a high lift cam in my current configuration.
 
Well....

Well, its been a long time since I've been in math class....but I just cant get the above numbers to compute.

From the beginning, I thought compresson ratio was:

Cylinder volume at BDC / Cylinder volume at TDC

In the case of a 1500 (actually 1498cc) X1/9 a single cylinder volume is 374.6cc and the compression ratio of a US version is stated to be 8.5 to 1.

Thus: 374.6 + total compressed volume / total compressed volume
= 8.5

Solving the above equation gives me a answer for the "total compressed volume" of almost exactly 50cc

If Pete's block has been shaved by 0.4mm (.04cm) then I figured he has reduced his "total compressed volume" by about 2.9cc (pi x r squared x height) , resulting in a new "total compressed volume" of about 47.1cc. Plugging this into the above equation results in his current CR being about 8.9 to 1

Now a piston with a CH of 34.9 as opposed to his current CH of about 34.5 should yield a similar reduction to the above shaving (that is another .04cm) for another reduction in "total compressed volume" by another 2.9cc or so. So new volume of about 44.2cc
Plugging this in results in a compression ratio of about 9.45 to 1

And yet Steve states clearly that " this piston will get your 1500 over 10.5 to 1" in Pete's case.

So.. I don't see how this is possible. Is it my math (likely) ? Or does Steve's piston have a big dome that he didn't tell us about ? (but wouldn't a big dome hit the head).Or is there a huge difference in valve pocket sizes ? (i wouldn't think likely - the higher CH pistons would need even deeper valve pockets).

Actually (well the way I calculate it anyways) you would need a "total compressed volume" of about 39cc to achieve a CR of 10.5 to 1. Which I reckon would be pretty tough to do without a highly domed piston or severely shaved head.

I guess it must be my methods of calculating being wrong. Because I have often seen it recommended here to "shave .100" off the head". According to my calcs, this would result in a CR of about 11.7 to 1 on a US spec engine !!

Now Steve, please DONT see this as any kind of attack or criticism. Just a friendly discussion. It's kinda bugging me cause none of my calcs seem to make sense compared to yours.

And just how high would you really want to go on CR, if you had the same crummy gas we have here - maximum octane on non-ethanol fuel is 91 (R+M/2 method) ?

Cheers,Doug
 
If the piston was to pop out the top of the block, the calculation would be based on this...

Volume at BDC is (swept volume - pop up volume )+ flycut and ring land clearance volume + gasket volume + chamber volume.

Volume at TDC is (volume in gasket - pop up) + flycut and ringland clearance volume + chamber volume.

The math "working backwards" was calculating on a swept volume of 1580cc, a stroker build with a standard bore size.

1580 /4 = 395cc per cylinder
395 + 48 = 443cc at BDC
48cc at TDC
= 9.23 : 1

as the stock 1580 is rated at 9.2:1, and I was trying to calculate the number for "TDC volume", and 48cc fits the result.

Pete has now changed his mind and looks like he's going with a 1500 build, no stroker crank.

He's going to use small flycut pistons with a higher CH than the stock large flycut 1500 pistons, so he is dropping roughly another 6cc from his TDC volume (flycuts go from 5cc to about .5 cc, the piston CH is 0,45 mm higher and as he already had a 0,40mm decked block are going to pop up by approx 0.3mm, and his head has already been skimmed to approx 33cc) ... run the numbers on this and you'll get about 10.5:1 ...maybe add a little to the flycut volume to allow for the enlarging of the inlet flycuts, but it's still a nice boost from 8.5:1

the calculations I did for Hussein looked like this, he is stroking his motor, and reboring to 87.0mm

87mm x 67.4mm gives 1602cc, so thats 400.5cc per cylinder
Euro cylinder head chamber volume is approx 33.5cc
the head gasket is about 87mm ID and 1.5mm thick when crushed, so it has a volume of approx 7.5cc
"pop up" volume is approx 2.87cc
Flycut and ring land clearance volume is approx 2.2cc

V * BDC = (400.5 - 2.87) + 2.2 + 7.5 + 33.5 = 440.83cc
V * TDC = (7.5 - 2.87) + 2.2 + 33.5 = 40.33cc

440.83 / 40.33 = 10.93:1 static compression ratio

These are ROUGH calculations, nothing beats direct measurement, as once again we will need to enlarge the inlet valve pocket, but this gives us an idea if we are heading in the right direction, Hussein should end up around 10.4/10.5:1 as well

SteveC
 
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Now I'm getting all my parts together for the build and am sourcing rod bearings and don't understand whether to buy standard or oversize? What's purpose of oversize bearings?

'PeteX1/9
 
Actually the correct term is Undersize, and these will fit a crank journal that has been ground to a smaller diameter,or undersize, usually measure in thousanths of an inch, in increments of Ten... so "ten thou under shells" will fit a journal that has been ground 10 thou under the standard diameter.

an Oversize bearing is something different, usually used when swapping components... and usually limited to engines that have a huge aftermarket base, like a Chevrolet small block ... and perhaps used when fitting a small journal crank to a set of large journal rods, and these would be "oversize backs" in that the extra material is on the BACK of the shell... hope that makes sense.

SteveC
 
I'm purchasing bearings for the connecting rods and some ads list undersize as you explained and some list oversize. In my case, which my crankshaft is original and never been machined should I be sourcing a standard rod bearing if I can find them or are they all under or oversized ?

'PeteX1/9
 
Never machined journals = standard size bearing shells.

If a vendor is listing shells to suit a reground crank as Oversized, they have their terminology incorrect, as this would mean bearings to suit a journal that is larger than standard...not one that is reground and a smaller diameter than standard.

SteveC
 
Thanks for clarifying Steve :)

Another question about bearings...Why are there so many different configurations in oil holes 1,2 or 3 and claim to be for the same model years and engine size?

I'll have my current pistons and rods out of engine block tomorrow so I could just wait to see what is currently installed and replace with the same hole configuration.

'PeteX1/9
 
1300 /1500 rods have the oil sprayers in different positions, so the big end shells are different because of that ...some shells are made to accommodate both types, and will have three oil holes.

Main bearings are a little different...there is actually a very small difference in journal size between the 1300 and 1500 (to the second decimal place, but I'm not going to try and recall this from memory)

The bearing shells are physically different dimensions because of this difference, so use the bearings with the correct dimensions to maintain correct clearances for your 1500.

SteveC
 
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Hey Pete

Greetings. Best of luck with your build, but ya gotta slow down a bit about ordering parts already.

You CAN'T (well you shouldn't) be ordering pistons or rings or bearings UNTIL the engine is completely torn down. Cause until you do that you are not going to know what to order.

AFTER the engine is completely torn down, then drag the block, crank, pistons, and rods down to your local machine shop for evaluation.

He will look at and measure your bores and tell you if they need reboring (you will then need oversize pistons) or if you get by with just a hone. Only when you have the pistons in hand that you are going to use, can you order the proper rings. If using used pistons, have him check those too.

He will look at and measure your crank. If damaged or scored or worn, he will have to grind the crank (in which case you will then need to buy undersized bearings). He can verify that the crank has never been ground before. If you are lucky, your crank might only need a polish -he will be able to do that too. Then, and only then, should you purchase new standard sized bearings. Maybe, if you are really lucky, he will tell you the existing bearings are just fine and you don't need new ones at all. There are main bearings and rod bearings, and don't forget this engine also uses seperate thrust bearings. Have him examine all three. If you trust him and he is competant, his advise will be crucial to your build.

And have him check your rods too, of course.

And , by the way, what crank and pistons have you decided to go with ?
 
Thanks for the great advice buddy. I'm not getting ahead of myself :wink2:
My block has been completely stripped down and have ordered:

-86.8mm Mondial 34.45 CH small flycut pistons which will be milled and balanced to leave .5mm pop-up and flycuts widened on intake side.
-Using a 67.4mm crankshaft which has been examined and polished
-Scat H beam con-rods from CNC balanced +/- 1gram
-Standard size rod and main bearings
-Fel-pro head gasket (1.5mm crushed)
-Miller's mule adjustable cam pulley
-Lightened flywheel by PBS

According to my compression calculator I should be sitting at 10.59:1 compression which was my target. A special thanks to all the members which helped steer me in the right direction and through their own personal experience showed me the way. Now just waiting for parts to arrive from all over the world and then off to the machine shop we go.

'PeteX1/9
 
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Perfect

Hi Pete,

that combination is exactly what I would choose next time (and for the most part have chosen).

What head is going on there now?
 
Perfect

Agree with Ulix and nice to see you've made a decision :thumbsup:

I'm now more confident that your build will be what you want.

and good to see you've found these unobtainium :rolleyes: parts that I keep going on about.... without too much drama.

That's the bottom end sorted, follow best practice and it will be strong and reliable.

What are the plans for the head??? This is where you'll make the power.

It will be interesting to compare your build and Hussein's, they will be pretty much the same bottom end ...in fact on paper they are almost identical.

He's going tipo 39.5/31 head and factory efi manifolding, your running carbs and similar valve sizes in PBS style head ...

But your looking at very different cams.
Grind ID: PBS SX1
110 lobe center
17-57/ 57-17 timing for 254 degrees duration (seat-to-seat),
220 degrees duration (.050-.050)
9.4mm (.380") maximum lift

Even a basic euro 1500 is 24/68 64/28 and 9.9mm lift on the intake (and that's duration at 0.5mm check clearance) so it has far more lift than the sx1... and at 50thou clearance it has a longer duration than the sx1.

What sort of flow does your "BVH" achieve?? If the guys that built it do "1000hp engines" surely they gave you some flow figures??? If your cam is 9.4mm gross lift, your nett lift (gross less running clearance) flow value is going to be the flow limit, and the power limit of the build, power is in the ports,reliability is what you build into the bottom end

Cam choice should be determined by head flow (and other things like static cr) and total lift set by where the ports "fall over" and start to loose flow.

I would have shot for something with a much higher valve lift.

Hussein's SQ will be different too, yours will be 0.75mm wider (about 50% wider) due to the decompression recess, all else being equal

It will make for an interesting discussion and comparison.

SteveC
 
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The head is a U.S 1500 BVhead which has been skimmed leaving .030" (0.76mm)recessed area, ported and flow benched professionally using 40mm inlet valves and stock exhaust valves. The intake manifold has been ported to match the head. Twin 45 DCOE Weber carbs with 32mm chokes fed by a carter fuel pump and a high flow filter passing through a fuel pressure regulator and gauge. Also running a 4-1 PBS tube header going to a single in dual out high flow muffler. I'm going to be using my PBS SX1 camshaft which has had the valves correctly clearanced to PBS specs.

I still want to upgrade my ignition system to either an MSD 6AL box or an Allison's automotive distributorless ignition but can't decide.
 
I do have my Faza 40/80 original grind but due to my longer valve stems which accommodated the PBS reduced base circle SX1 cam I can't adjust the valve clearances. Do you have any recommendations? If I could source a more aggressive PBS cam then I would go that route or would a re-grind which has a smaller then stock base circle be a good alternative?

I've always liked these camshafts, specifically the "Ultimate Road" grind as the stated power band looks well suited for spirited street driving.
http://www.pipercams.co.uk/pipercams/www/product_nav.php?type=C&cat=CM&man=7&engine=244


Or this camshaft from Midwest looks really good.

http://www.midwest-bayless.com/stor...l.aspx?sid=1&sfid=208227&c=193056&i=250929213
'PeteX1/9
 
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The Piper cam I can see comes as both a regrind (repro = reprofiled) and a billet. You need to determine what base circle the repro cam has, and figure if it will work with your extended valve stems ... ultimate road looks good, doesn't have loads of LATDC, which could suit. A whole extra mm of lift over the sx1 will definitely suit the larger capacity. The shorter duration and higher lift would suit an engine that didn't rev to a million...and remember your engine is now a longer stroke so it just won't physically do the same sorts of revs as a smaller stroke option ..it would also suit the higher piston peak speed of the 1600 better...the bigger valve lift is going to make more difference than the last few extra degrees of duration.

Same with Matt's cam, it's reprofiled, so you need to determine the base circle diameter here too (but I know Matt will have this info if you ask him) Matt skims his camboxes by about 1mm, so this cam could work with your extended valve stems and a stock cambox. It has less lift than the piper but longer duration.The extended duration would be more suitable for higher revs.

If they work with your extended valve stems then IMO either would be a positive step for output over the sx1.

SteveC
 
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