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A16 - Concept
No life (a.k.a. DattoMaster)
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So I was procrastinating the other day, looking in the ACL catalogue and came up with this combination:

GA16/E16 crank (88mm stroke)
A14/15 rods
Honda EL (1602cc) pistons (ACL# 4MKRY2772)

The pistons have a 18mm pin so that would have to be replaced with a 19mm pin alternatively bush the rod. They also have a 27.50mm comp height, with the longer stroke they'd come 0.5mm further up the bore which shouldn't be too hard to cope with.

Seems like a strong possibility for an A16 using an A14/15 block and rods. I'll never get around to it but it's a fun thought.

Posted on: 2013/9/18 9:34
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Re: A16 - Concept
No life (a.k.a. DattoMaster)
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Has D hacked your account joke

Posted on: 2013/9/18 10:31
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Re: A16 - Concept
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Nice idea. If the rod end matches up it sounds do-able.

Couldn't you use stock A15 pistons?

E16: 76 x 88 mm bore and stroke
A15: 76 x 82 mm bore and stroke

oh i see they would stick out of the bore half of 6mm

A15 pin height: 30mm
EL pin height: 27.5

there's the .5 mm you mentioned. EL has 77mm piston for 1639cc @ 88mm stroke.

Posted on: 2013/9/18 10:43
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Re: A16 - Concept
No life (a.k.a. DattoMaster)
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Not bad hey

Nope no hacking going on here. I still think a turbo is easier but if you were pushing for every last bit.... I should've spent that 20 minutes working on my car instead.

Posted on: 2013/9/18 10:46
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Re: A16 - Concept
No life (a.k.a. DattoMaster)
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(Lemonhead) has the e16 crank worked out in the big block A series block with sleeved 82mm bores for 1800+ something cc. He said his engine builder belives 83mm is possible with 83.5 to 84mm max using offseting the bores (for anything over 80mm). He was aiming for close to 1005 or 1951cc last I heard using either 83 or 84mm bores.

Problem with the e16 crank is they are rare and have small rod journals or crankpins for very cool looking rods this means the A series rods do not fit but its much easier to offset stroke the A15 crankpins from 82mm to 83mm using oversized bearings matched to 83mm bores to suit ca18de pistons you get some major capacity and only spend the money on the sleeves, crankpin mods and balancing etc.
The E series crank needs serious work to fit into the A block so its much easier to mod the A15 crank mildly and use sleeving/o-rings.

1796cc with 45mm webers should be torquey enough :) with that high port custom A series head concept along with boost should be close to a CA18det up to 18-20psi if custom manifolding is well sorted.

Posted on: 2013/9/18 14:50
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Re: A16 - Concept
No life (a.k.a. DattoMaster)
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WIth a turbo setup, you'll make more power as boost levels rise by having thicker/better supported bore walls and it also helps to have a piston without too high a pin placement. anything that can flex will lead to ring seal issues, and this is highly magnified with boost. It's not just higher pressures, it's the pressure curve. On an NA engine, the combustion pressure (relatively speaking) bleeds off after the piston starts moving down the bore, but it (the piston) is still relatively high in the bore. Good seal. With a turbo engine, since there's more air and fuel in there, the pressure doesn't bleed down as the piston moves downward (at least nowhere near as fast as with an NA engine) then you have (for illustrative purposes) the piston way down i the bore. In the middle of the block, the cylinder wall is less supported than up near the top (the deck adds a lot of support of course) and more room for flexing.

In the end it's about how much air you can get in/through the head, and since the head is going to be a restriction sooner or later, these really long stroke combos (in this specific example) start to be a case of rapidly diminishing returns. Ultimately such a combo will almost certainly not make more power than something closer to std a15 stroke and a moderate overbore in NA form. What the stroker setup will do however is likely make that power at a lower rpm and have more peak torque. It'd work pretty well in a rally car, or possibly a circuit racer.

If you are going turbo, you'll make just as much power with a std bore a15 than with a stroker engine (at least in this specific combo). I've done this to death on other engines (including ford 221 cranks into holden 186 blocks with ford 250 pistons for 230ci - you can get 234ci but that requires red motor rods with their slightly smaller rod bolts, as you can't clearance the block enough to clear the rods and retain enough strength with blue motor/bathurst rods, not a desirable thing on a much longer stroke to run weaker rod bolts. But they don't make more power than a full race 202 (they do make more mid range torque and are a pretty good, though admittedly expensive street motor option). But once you go turbo, the std bore 250 pistons are a 55thou overbore for a 186/202 block, and they basically don't make more power than the 202 based combo will (unless boost levels are reduced big time which defeats the purpose of going with a turbo in the first place!). Bottom line, add turbocharing, and the shorter stroke and thicker bore wall combo is worth more power. back in the 80s wayne mankhen (spelling? - heck it's that long ago I'm not even sure if his first name was wayne!) ran a 186 block that was sleeved down to 179, and it made more power, iirc he was running over 30psi boost...

To be fair the honda piston (if every other attribute of it suits, and I don't know for sure) is a reasonable bet at least since it doesn't require a huge overbore. but 88mm stroke is still pretty big.


The bottom line is really big overbores and long strokes aren't all they are cracked up to be when combined with a head with limited flow potential. I'm not criticising the datto heads, by the way. You can get tremendous power out of an a15 all things considered. But trying to support enough flow for something in the 1600 (let alone 1700-1800) cc mark at realistic race rpm ranges is a bit to ask of it.

It's all about finding the best combination (or more accurately combination of compromises) that ends up with the best overall result, and that combination, and optimal result will vary greatly from application to application. A case in point is rod length vs stroke. In very very very general terms, a longer rod means the piston 'turns around' slower at top dead centre. This (and during the exhaust stroke, since there isn't compression pressure of a few hundred psi above it like on the compression stroke, which helps cushion the turnaround) is the point where a rod will start to let go. It might end up flung out sideways, but it's at that TDC turnaround that is the critical moment. also a longer rod has less angularity around the 90 degree (crankshaft rotation) point, so less side thrust, less friction, less chance of seizing, less bore wall distortion etc. So a longer rod is better right? NOt always. Certainly anything shorter than around 1.6:1 (rod centre to centre distance 1.6 times the crank stroke) will see power and reliability gains as you go with a longer rod (assuming it will all fit) BUT if the piston spends much more time up close aroun TDC then you can't open the intake valve as fast, or it'll hit the piston. Similarly you have to close the exhaust valve earlier, as the piston will be up there and hanging around during that valve overlap time. So that'd mean you'd have to (esp when it comes to race engine rpms and valve lift rate and opening and closing time) have a cam with slower intake lift in the early stage, or possibly wider lobe separation angle, or deeper recesses in the piston crown. All of which can cost power. Additionally - and this is highly rpm specific - a shorter (relatively) rod with the piston spending less time at TDC, well the piston starts down the bore more aggressively in the initial moments of the intake stroke, and this can create a stronger signal, getting the intake flow happening sooner and more significantly. Paradoxically, the shorter rod also means the piston dwells around bottom dead centre longer (whereas a longer rod slows it around TDC but moves quicker around BDC.) This is very important, because by that stage in the intake flow, it's less about signal strength, and more about the inertia of the incoming air. So if the piston doesn't start to rise up quite as aggressively, it's easier for a tiny bit more intake air to get in there and not be stopped dead, or pushed back up out.

In other words, especially on more modest rpms (and this applies even to circuit race engines of this type. It's obviously not the case for engines spinning 11,000rpm or more (also they would all typically be multivalve, so they will flow more (unless they were designed by muppets) than a 2 valve head will, and won't require as much valve lift to do it either, since each of the intake valve pair is smaller diameter, it doesn't have to lift as far open to get near peak flow lift ranges (potential peak flow range), which is partly a function of valve diameter - i.e. when you reach valve lift a certain percentage of valve diameter, you get near to peak flow, and opening the valve more will show less and less gains. so multivalve heads have a big advantage here.


Point of all these tangents, be very careful about really big capacity increases and their benefits, as often you end up piling up too many other 'side effects' along the way that it undoes the harm.

totally hypothetically, if I 'had' to run an A series based combo, and 'had' to run normally aspirated, there's definitely some scenarios where a long stroke crank and overbore would work. But if I had access to a turbo, I'd be running a regular a15 based setup. If the limitation was on engine capacity, but engine choice was open, perhaps to engines of the same manufacturer and time period, then at 1600-1800cc there'd be more power to be had from starting with an L series 4 cylinder. And if motor choice was free but capacity still limited, it'd be hard to beat an SR16 based combo. You could (and there's someone here who has proven that beyond any doubt) run a fairly modest sr16 combo, with only minimal mods (or at least the mods wouldn't cost much or involve major hours labour wise) would outrun (and thanks to overall specs - shorter stroke, bigger bore, much better breathing head - 'as is' also outlast) a big dollar a15 combo. There's a race category (I forget the name sorry) a bloke on another forum races in. they were allowed either and almost unrestricted highly modded 1.3 litre (the 3k toyota one was what he was using) pushrod 2 valver, or a highly restricted (very little mods) multivalve 1.3. He went with a suzuki swift based motor. It made about the same power, but with a broader powerband, and it didn't need to be rebuilt every season, would pull out of corners a lot easier, etc etc).

Posted on: 2013/9/20 10:57
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Re: A16 - Concept
Just popping in
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Currently getting an a16 built at the moment... Will provide details when its finished

Posted on: 6/4 0:34
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Re: A16 - Concept
No life (a.k.a. DattoMaster)
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Many have had 79mm bore A15 which came to 1.6 so we referred to them as A16
but an E16 cranked A15 could go to 1700+cc

Is yours just a big bore A15

Posted on: 6/4 4:08
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Re: A16 - Concept
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I have an E16 crankshaft for sale
Crack tested
Ground
Comes with bearings
Pm me only for details

Posted on: 6/4 8:40
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Re: A16 - Concept
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thanks for your input jmac always enjoy reading what others think -- i have a na A15 almost 100kw on a base map [not even finished properly] and now i've got another A15 and this is going to be a turbo motor [size of the turbo is my problem --big or small?]

Posted on: 6/4 18:06
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