2110cc Detailed Build Thread - Now 2276 Super Squish Build

[hotrodsurplus]

The peaks and valleys of 80-120 grit sanding scratches should leave plenty of surface area for heat transfer.

That sounds just fine.

The outside of the block will be painted with either black or dark grey wrinkle paint so it will have more surface area than normal, although I'm doing it for looks more than heat transfer.

I would look further into that. As plastics are naturally insulators, paint should theoretically inhibit heat transfer. I understand that the crinkle has greater surface area; however, I would question whether it's enough to offset the insulative properties of the paint itself.

I usually left my cases bare but nowadays I'd consider a mag-specific alodine treatment. It's a conversion coating for paint prep but it can serve as a final coating if it's not exposed to UV. It's more of a wash than a coating. It just turns metals golden. Dow 7 would be killer but probably not practical. I think there might be another chromate coating but you're not likely to find it unless you work in aerospace.

My point is that I'd keep the case as bare as possible. There's a functional aesthetic to bare mag too.

From my research, by using the Super Squish pistons the head temps will drop about 100 degrees,

Correct me if I'm wrong, but from the way I understand it those pistons require tight deck heights to work properly, right? Apologies in advance for hijacking the thread, but the traditional way to improve squish is to decrease the deck height, which of course can push the compression ratio through the roof. If I understand it properly, the volume in the piston crown maintains tractable compression ratio at tighter deck heights (in other words the pistons are dished so you can tighten the deck). Otherwise it seems to me that the effect is lost. For example, running a .110" deck height will make the engine run just as hot as if it had flat-tops in it. I'm not challenging anything as much as trying to understand the premise of these pistons (among other things I'm wondering why they're not just called dished as they are in the rest of the world).

I'm all for tight decks. Every cool-running engine I've ever built had a .045 to .055" deck height. Every hot-running engine I ever had ran looser deck or heads destroyed by semi-hemi (anti-squish, so to speak).

In some cases power pulleys and even dry sump pulleys are needed to slow the fan down enough to let the engine get up to propper operating temps.

Those are the thermostats' job isn't it? I'm with you that you can probably get away with a smaller crank pulley without impairing cooling, but an engine with properly operating thermostats will reach at least op temp regardless of the engine's efficiency.

Thanks for posting! As I've said before, all relevant info is welcomed and appreciated!

And thanks for letting me clog up your thread. I'm interested in this build.

[theastronaut]

I would look further into that. As plastics are naturally insulators, paint should theoretically inhibit heat transfer. I understand that the crinkle has greater surface area; however, I would question whether it's enough to offset the insulative properties of the paint itself.

I usually left my cases bare but nowadays I'd consider a mag-specific alodine treatment. It's a conversion coating for paint prep but it can serve as a final coating if it's not exposed to UV. It's more of a wash than a coating. It just turns metals golden. Dow 7 would be killer but probably not practical. I think there might be another chromate coating but you're not likely to find it unless you work in aerospace.

My point is that I'd keep the case as bare as possible. There's a functional aesthetic to bare mag too.

I'm planning cleaning the block with PPG DX series aluminum cleaner and then doing an alodine treatment before a light coat of PPG DP90 to promote adhesion. Still planning on painting the block, I can't stand the look of bare oxidized mag. I would think that any rise in temperature due to the paint acting as an insulator will be small and not worth worrying about.

Correct me if I'm wrong, but from the way I understand it those pistons require tight deck heights to work properly, right? Apologies in advance for hijacking the thread, but the traditional way to improve squish is to decrease the deck height, which of course can push the compression ratio through the roof. If I understand it properly, the volume in the piston crown maintains tractable compression ratio at tighter deck heights (in other words the pistons are dished so you can tighten the deck). Otherwise it seems to me that the effect is lost. For example, running a .110" deck height will make the engine run just as hot as if it had flat-tops in it. I'm not challenging anything as much as trying to understand the premise of these pistons (among other things I'm wondering why they're not just called dished as they are in the rest of the world).

I'm all for tight decks. Every cool-running engine I've ever built had a .045 to .055" deck height. Every hot-running engine I ever had ran looser deck or heads destroyed by semi-hemi (anti-squish, so to speak).

I'm about 99% sure theres no dish in the piston tops. Havn't seen a set to prove it but knowing the theory behind them and pretty sure I know the guy that developed the idea (and seeing pistons he's designed for other engines), I'd be willing to bet that they don't have a dish; just the opposite. I don't want to be too specific as John at Aircooled wants the design guarded to keep copy cats from ripping off his product. There's a reason why they require modified cam timing; to keep the piston from hitting the valve at TDC. That wouldn't make sense if they were dished. There is increased squish this way, and also the reason why they raise the compression. I guess a way to say it is that they add squish in areas other than the usual tight quench pad to piston clearance.

Those are the thermostats' job isn't it? I'm with you that you can probably get away with a smaller crank pulley without impairing cooling, but an engine with properly operating thermostats will reach at least op temp regardless of the engine's efficiency.

I also wondered if the cars needing smaller pulleys were using thermostats and flaps when I read that. Seems that they weren't but I can't say for sure. Even running thermostat/flaps, if it runs cool enough to use a smaller pulley then I'd definitly run it that way. Slowing the fan down will require less hp to turn it; I'm all about small details that can pick up a couple extra ponies.

And thanks for letting me clog up your thread. I'm interested in this build.

You're not clogging it at all, I'm glad somebody's putting some though into what I've planned and is willing to share their views and opinions!

[hotrodsurplus]

a light coat of PPG DP90 to promote adhesion. Still planning on painting the block, I can't stand the look of bare oxidized mag. I would think that any rise in temperature due to the paint acting as an insulator will be small and not worth worrying about.

I'm the first to admit that we're probably splitting hairs with block paint. As for oxidized mag, I've never had a problem and I live in the northwest. The light film of oil on everything seems too keep the white fuzz at bay. I run mag Halibrands and a Ford roadster (real mag, not the colloquial 'mag'). I spray them with Gibbs-brand oil and they stay light gray--about like as-cast aluminum. Don't get the idea that I'm trying to talk you out of anything.

As for a surface finish, DP90LF makes a GREAT chassis/engine paint. As long as it's not exposed to UV it will stay nice and black for pretty much forever. All of my cars' inner fender wells and firewalls are DP90 and they're as black as the day I sprayed them. I'm pals with a PPG rep in Portland. He works in fleet and says there are a number of applications where the DP is considered a finish coating. Something to ponder (and it's cheap, too).

I'm about 99% sure theres no dish in the piston tops.

I asked John what the crown volume was and he said 4cc, so there is some sort of void (dish, bowl, whatever). I think it might be as simple as a bowl that mirrors the general chamber shape.

I don't want to be too specific as John at Aircooled wants the design guarded to keep copy cats from ripping off his product.

This isn't to knock John as I don't know him. In fact, by his presence he seems to be pretty knowledgeable. He's at least done some homework, so for that I commend him. But I don't understand what the deal is with the 'closely-guarded secret.' I mean if anyone wanted to know they'd just pony up the $400 for a set of slugs. That's cheap for R&D (receive and duplicate). Nothing will stop the copycats.

Anyway, there's nothing new under the sun. A lot of what passes for high-tech modern engine design dates back to Harry Ricardo's research with chamber designs that he published in The Internal Combustion Engine. in 1922 and 1923. His subsequent books outlined the principles behind high-turbulence combustion-chamber design.

Basically Ricardo proved that a few simple principles (tight deck, small chambers among them) upset the fuel mixture as the piston compresses them. The turbulence that results helps propagate the flame. It also reduces the amount of ignition advance the chamber needs to light the fire during the combustion phase. And the side effect of this efficiency is greater detonation resistance. In John's marketing material he states that engines with 'squishy' pistons can take advantage of higher compression ratios. Well that's a sign of a more efficient chamber design (and remember, the piston is part of the chamber).

Now I don't want to reduce those pistons' design to just 'dished.' For all I know he may have a dish accompanied by a raised quench pad. That's entirely possible. In fact it's likely in light of the need for the modified cam timing.

Now are you sure that it's not a matter of the pistons raising the compression or that the pistons allow the engine to operate with more compression without detonating? I personally think it's the latter. But by what he told me those pistons had a crown volume, which indicates a dished area that's larger than any dome.

I guess a way to say it is that they add squish in areas other than the usual tight quench pad to piston clearance.

Yep, that sounds like it would be a quench pad.

I also wondered if the cars needing smaller pulleys were using thermostats and flaps when I read that. Seems that they weren't but I can't say for sure. Even running thermostat/flaps, if it runs cool enough to use a smaller pulley then I'd definitly run it that way. Slowing the fan down will require less hp to turn it; I'm all about small details that can pick up a couple extra ponies.

I'm all for thermostats. I don't understand why the air-cooled crowd thinks it's just fine to run an engine without them. Drag cars without water jackets or those with filled jackets aside, all performance water-cooled engines that I know of run thermostats. Without them the piston is always trying to expand in a cylinder that's always trying to contract. It blows me away when I see the scuffed skirts on peoples' pistons. For whatever reasons my engines don't suffer that (I chalk it up to favorable expansion rates that a thermostat allows). But forgive me; I know I'm preaching to the choir.

And I'm all for reducing frictional losses if the engine can live without the extra cooling air volume. I think people make a bit too much out of stock-sized pulleys. I mean they have their time and place, but look at the average VW dual-port 1600 engine. They have about .065" deck PLUS a .055" step in the head. That's a FAT deck! I mean you have to try and get a flame front across the whole bore! The surface area is INTENSE! That greater surface area combined with the extra time spent burning the mixture will make ANY engine run warm! It's almost surprising that those engines will run as cool as they do.

But when you run tight decks you confine the combustion surface area to the comparatively smaller chamber for the duration of the hottest part of the burn. So in that sense the fire in the hole has less of a chance to transfer heat to the head. Then there's also the ignition timing. Confining the burn to a smaller area also requires less lead timing. So you can fire the plug later. And let's face it, the later we can fire the plug the less time the combustion process has to transfer heat to the chamber. Lighting the fire real early in a bad chamber design increases the resistance on the piston as it's on its compression stroke--the engine basically fights itself! But the tighter chamber mitigates all of that.

And that brings me back to my main point: increasing the engine efficiency alleviates some of the burden on the cooling system. And a slower fan speed may sufficiently cool the engine if the cooling system doesn't have such a load. So I'm open to the idea that a properly designed engine doesn't need a huge pulley. It's not like we're going to climb hills at 35mph in fourth gear. Auto designers have to account for bad driving habits like that. That might be what justifies the large pulley.

Man, that was long winded!

Anyway, if you want to read up on a more concrete example of what serious builders are doing with squish, read the following. It's not even all that new, either.

John Kaase is an engine-building demigod of sorts. He's won Popular Hot Rodding's Engine Masters program in the past with engines he's built. I don't know if you are familiar with the program, but builders have to design engines that run on pump gas. They tally the dyno figures and calculate which engine made the most power across the entire range (rather than peak horsepower at one speed, for example). It's a great program that takes the whole engine into consideration rather than a few figures, and it's really opened a lot of peoples' minds to engine design.

Anyway, in '05 Kaase built a 510 Poncho that made 820hp and 767lb-ft torque--again, on pump gas. Among other things, he ran a 37cc chamber. Now even in VW circles a 37cc chamber is TINY. Forget about building a 2.3-liter engine--four cylinders of a 510 comes out to 4.2 liters. Now imagine a 4.2-liter boxer with 37cc chambers. Now imagine giving it .035" quench clearance (deck height).

He got away with that by using a piston with a fairly substantial crown volume that reflected the shape of the chamber (mirror dish). So the chamber was narrow so the flame could get across it fast; it was just deep, which is still easy for the flame to get across quickly enough. Even then the static CR worked out to 12.4:1 static CR. Now of course the huge duration on the cam bled off a bunch of pressure and got the effective CR to a normal level that could run on pump. But even then I can guarantee you that the effective CR is a lot higher on that engine than it would be in a 'normal' performance engine.

Now I fully understand that you're not building an engine to the same order as Kaase's, but a lot of the same principles that he used apply to what we should be doing in this neck of the industry. I mean there's nothing saying that our air-cooled engines can't run long and well on pump gas with 10:1 static CR. It just takes good chamber design, correct cam timing, and so forth.

Man, talk about making an already long-winded entry even longer!

If you want to read more about Kaase's engine, read the PHR article at

http://www.popularhotrodding.com/engine ... index.html

[theastronaut]

I asked John what the crown volume was and he said 4cc, so there is some sort of void (dish, bowl, whatever). I think it might be as simple as a bowl that mirrors the general chamber shape...

...Now I don't want to reduce those pistons' design to just 'dished.' For all I know he may have a dish accompanied by a raised quench pad. That's entirely possible. In fact it's likely in light of the need for the modified cam timing.

Now are you sure that it's not a matter of the pistons raising the compression or that the pistons allow the engine to operate with more compression without detonating? I personally think it's the latter. But by what he told me those pistons had a crown volume, which indicates a dished area that's larger than any dome.

Did he say if it was positive or negative volume? Not having seen a set, I still think it would have to be positive, as in a dome. If they were just dished then the cam timing could be the same as a normal hi-po build. Even if there was interference, cutting valve notches would solve the clearance problem. But if I recall correctly, Jake Raby tested them and cut valve reliefs in what I believe to be the dome and ran normal (or closer to normal cam timing) and they didn't work as well as running them the way they're meant to be run. This leads me to belive that they have a dome, that it's there for a specific reason (again, going back to knowing who developed them and his theory) and any modifications to it will hurt the quality of combustion. Either way they definitly aren't flat tops and whatever the shape is it greatly contributes to much more efficient combustion.

I'll know what they are for sure next week tho, and once the cylinders are here I'll mock it up, drop the piston down the cylinder a certain amount and measure the volume. Then I'll do the math for the volume that a flat top would be, and then be able to tell whether or not the difference in volume is positive or negative.

Interesting reading for sure! I think we're on the same page concerning combustion theory and it's great to see someone like you applying their knowledge to aircooled engines!

[hotrodsurplus]

Did he say if it was positive or negative volume? Not having seen a set, I still think it would have to be positive, as in a dome. If they were just dished then the cam timing could be the same as a normal hi-po build.

I tend to think that there's a dome and a dish. The crown volume is only 4cc. That's tiny--barely a bump. For any kind of quench pad to work it would have to be fairly substantial, and for substantial to happen it would have to be fairly big--bigger than a 4cc dome. I'm betting that the dome (or quench pad) is fairly large and there's a fairly substantial dish aside it. Of course I can't say for sure, but I can speculate based on the peestones I've used in domestic engines.

Even if there was interference, cutting valve notches would solve the clearance problem. But if I recall correctly, Jake Raby tested them and cut valve reliefs in what I believe to be the dome and ran normal (or closer to normal cam timing) and they didn't work as well as running them the way they're meant to be run.

That wouldn't surprise me. I don't know the specifics so anything I'd say is just conjecture, but I do know that engines that run very high compression ratios can benefit from non-standard cam timing (differing intake/exhaust duration, for example).

Interesting reading for sure! I think we're on the same page concerning combustion theory and it's great to see someone like you applying their knowledge to aircooled engines!

I'm glad more of us are getting serious about these things.

[drmiller101]

the 2 stroke guys have some advantages in head design as they don't have to worry about those pesky valves. They are doing some pretty serious games with squish.

they are running perfectly circular chambers with squish around the perimeter. The squish angles is pretty important.

The theory is as the piston gets close to TDC, the volume between the head and piston are changing. you don't want to create a LOT of pressure by having the piston and head parallel, but you want to have the velocity pretty high at the edge of the squish.

Also, the hope is to have the gasses moving around quickly past hot spots in the combustion chamber so a hot spot doesn't lead to detonation.

I think.

[hotrodsurplus]

the 2 stroke guys have some advantages in head design as they don't have to worry about those pesky valves. They are doing some pretty serious games with squish.

Absolutely. To a lesser degree the four-valve guys are really pushing things too. It's nice to have the fire start right in the middle.

The theory is as the piston gets close to TDC, the volume between the head and piston are changing. you don't want to create a LOT of pressure by having the piston and head parallel, but you want to have the velocity pretty high at the edge of the squish.

I understand that from a slightly different perspective, but it's the same principle nonetheless. The rate of pressure rise is very critical. Too fast of a rate can cause spontaneous combustion. I've heard a rule-of-thumb threshold is 30psi per crankshaft angle. I have an engine dynamics calculator that can do that but I have yet to figure that part out.

That's one of the issues that higher connecting-rod ratios amends. That Berg guy used to rail against people for saying that a 2:1 rod ratio was favorable. At the same time he would praise VW engines built with stock strokes and con rods. Well the 1300, 1500, 1600, and all the variants like 1680, 1776, and 1914 have a 1.97:1. Cognitive dissonance?

I'll leave it at that before I hijack this thread to places its creator probably didn't want to go.

Also, the hope is to have the gasses moving around quickly past hot spots in the combustion chamber so a hot spot doesn't lead to detonation.

I'm sure that's a consideration too. I always understood the principle was to create enough turbulence to help distribute the flame. Flame speed is actually quite slow. Thrusting it from the crevices, on the other hand, causes the flame to whip around (in a controlled manner, mind you).

There's also one other thing about quench area that I don't think gets much attention. The piston head and chamber are actually too cold to support combustion. I've heard that any fuel within .025" of the surfaces won't burn. following that theory, there's no way for a flame to burn the fuel in the squish area. That fuel is still trapped in there, however. Ever notice how an engine with a lot of deck (or an engine with semi-hemi heads) requires a lot more fuel than a tight-deck engine? I do; in the early '90s I drank the Kool-Aid and had a guy carve my head's chambers into that semi-hemi profile. Hey, it was the style at the time.

[Stripped66]

Astronaut,
I'm going to be moving to Charleston in August. Obviously I won't be terribly close to you, but there's probably few guys running Squishies who's closer.

I see you opted to buy a set of bare heads instead of a set that's ported? What are your plans?

[theastronaut]

Astronaut,
I'm going to be moving to Charleston in August. Obviously I won't be terribly close to you, but there's probably few guys running Squishies who's closer.

I see you opted to buy a set of bare heads instead of a set that's ported? What are your plans?

I had originally planned on buying bare mexican 043 heads and have someone weld up the chambers. I wanted to reshape them with larger quench pads, but now that I've decided to run SS pistons I'll probably buy heads already ported and leave the chambers alone as the SS pistons accomplish what I was originally hoping for with a fast burn chamber design. I've heard alot of good about CB's wedge ports but still havn't made my mind up. I'll get the bottom end mocked up and everything sorted and then turn my attention to cylinder heads.

[Clatter]

Aren't there heads with chambers specifically designed to work with the SS pistons?

I thought Darren or John had 'em...?

[theastronaut]

Aren't there heads with chambers specifically designed to work with the SS pistons?

I thought Darren or John had 'em...?

From what I've read the chambers need to be clearanced for the dome. Not sure if anybody makes any other mods to the heads when running SS pistons.

[theastronaut]

Macdweal, John at Aircooled doesn't want pics of the SS pistons posted. I asked the mods to remove them but if you see this first, please edit them out.

[stoneloco808]

Oh crap, get ready for some new pistons to be coming out from AA, QSC, and whoever else...

[sideshow]

Is the SS dome on the intake or exhaust side?

[Piledriver]

Is the SS dome on the intake or exhaust side?

It's on the intake side, and why you need the late/wide LC valve timing.
The idea is to force the A/F charge//flame front over to the red hot exhaust valve, which will force a fast burn.


A photo of the SS pistons was posted on ENDYNs website for many years, its ENDYNS std design for any wedge 2V head.

John is just trying to protect the R&D time he put into it, I STRONGLY (cough) suspect ENDYN will sell you a set any size/pin height/dome you like...
...very reasonably too.
... But then you get to figure out your own the cam/timing requirements.

Mods: Remove the link above to appease John, I can't, but the "generic" pic from ENDYNS site is available if you know where to look.

If the pistons are not of aircooled.net parts, disregard.