Geis

Welp, seeing how turbohatchy has been busy trying to keep discussions alive I figure I may as well too, in a dedicated thread this time

Anyways, I've been in some discussions on engine builds over with our buddies at Ti, and there was an interesting article that I had read going over the limits of the B series engine design in terms of being undersquare, and how to increase displacement etc.

Link : Engine Package : Swapping Parts For Power - Team Integra Forums - Team Integra

My question is would making an oversquare layout for our engines be beneficial with the addition of turbocharging? Near the end MD gives an example of people boring out ls blocks to 84.5mm (or b20 blocks), using LS rods, and a b16 crank to achieve a displacement a bit over 1700cc, oversquare layout that would in his own words 'rev like a bike engine'

So, there's obviously the trade off of lost displacement, which could easily hinder low to mid range torque capabilities, yet in exchange (from how I understand it) you have an engine that produces a better burn, uses more of the power generated from combustion, has better capability to intake/exhaust fuel mixture, and is generally much more stable at higher revs due to less vibrations in the cylinders. This obviously goes hand in hand with the high revving 4 banger philosophy anyways, seeing how we lack an real torque down low.

The loss of displacement wouldn't be as much of an issue I would necessarily think either; many people run stock 1800cc turbo setups with great power bands, hell even a non honda guy is running a 600+whp l.8Liter toyota powered Lotus canyon monster, I'll have to look around to see if I can find his dyno graph but from his videos the motor seems to spool ridiculously fast for not even being a 2liter....This all combined with the fact that I've seen a few very knowledgeable members here (not going to put out names) that have kinda treated 2liter as not that big of a deal. I do realize many people run 2liter for extremely high power setups, and though I haven't taken the time to compare them I imagine they do make torque a good amount sooner.... the point being that 1.8s still have their place and I doubt that less than 100cc of difference will be the breaker between the oversquare setup and the b18, but will it be a deal breaker between the 2.0?



Mind you this is coming from a boost (well, anything tuning wise) n00b, I've been around lurking and researching and have finished piecing together a kit (need to finish up some things so I can get around to installing) and was considering the oversquare layout in the fututre. I already am going into this with a b20 and always thought my higher displacement would make for a superior build (yes I know about the sleeves) but after reading this article I started to have other thoughts. The only other doubt about it other than sacrificing displacement I had was in the article he more on the topic of all motor builds (at least that's the jist I was getting) so maybe this would be horrible for turbo..

Lemme know what you guys think

wantboost

iTrader: (2)

<p>What you're forgetting is the cost of having custom pistons made. Then there's all of the math and measurements to figure out for the pistons.&nbsp;</p><p>But really this is too much work for not much point. Just because it can rev high doesn make it better. Plus a street car would rarely have enough room to stretch it's legs like that and that combo would produce virtually no torque. So you've basically taken the high string nature of Honda four cylinders and made it even worse.&nbsp;</p><p>This kind of thing works on bikes because they weigh next to nothing, they don't need torque... But 2600lb+ cars most definitely need torque. It would a be a turd.&nbsp;</p>

turbohatch96y7

iTrader: (15)

Arent th h22 and k24 guys reving to 9k plus?


Are you after a better r/s ratio?

Geis

Why would you need custom pistons, they don't make 84.5 millys?

Geis

I dunno man it just kept being suggested by a member on TI and I finally took the time to read the entire article. K20 is already perfectly square

wantboost

iTrader: (2)

With the deck height, rod length, and stroke it would require custom pins with modified pin heights to get the piston to sit right in the bore.

Geis

Damnit man I'm always forgetting the small stuff.
Ofc it would be the pins that screws this setup over. I would still be interested to see what it could do... you think it would be worth it if you could rev to like 10000+

The article was written by MD and he (obviously) is no dumbass, so now I guess I'm just wondering what his point was with suggesting that setup, and he said others had been using it as well soo...curious to see what you think.

efHondefender

there's no reason to lose torque by reducing stroke/displacement, unless the motor cannot breathe or doesn't have geometrical integrity at the highest reasonable rpm that produces the best powerband for the application. That said, undersquare Honda motors still tend to make power all the way to pretty damn high rpms. I would only shoot for an oversquare setup on a B series if I were looking for more reliability at a target elevated rpm. Mostly because of rod angle and piston speed reductions. Going to a max bore can greatly reduce reliability, especially in a turbo application. Whether it be head gasket sealing or liner strength concerns. If I were gonna do a oversquare setup, I'd probably just do a b16 with a modest overbore. Maybe 82 or 83mm. You could run a longer rod with a taller b18 block, but that will reduce peak piston speed and may cause a negative effect on average power production. Remember also that 4 valve motors can get away with smaller bores because they make more effective use of the area of the bore. On top of that, sometimes smaller bores can have more efficient combustion due to the flame taking less time to travel across the piston. This means less ignition timing is needed and therefor less negative pressure pre-TDC or BTDC.

theYBLEGAL

Slightly off topic/but relatedish. Crazy vid buddy showed me today.. You guys talkin about oversquare motors is funny coincidence

Geis

My lord...that has to be one of the most amazing setups I've ever seen.

He went from like 30-160mph in a few seconds....
Those cams were bogging like crazy at around 5k rpms.... crazy setup.
I'll have to see about making an insane turbo anything setup thread here in Fi if the mods are cool with it, where you can post any car as long as it's off the walls like this. Thanks for posting

HiProfile

That evo is all show, no go. Any time they try to race it in any sense (track, street race), something happens where they can't race.


There is only 1 reason to reduce stroke - because you are limited to a certain displacement. Then you get a custom head, cams, intake, header(s), etc to move your powerband.

Since 99.9% of Honda people use an OEM cylinder head casting, 99.9% of them will increase stroke if they can. Every 1 cc gained from increasing stroke is worth more than 1 cc from increasing bore. Look at every non-limited Honda motor series. They will sell their organs to get the largest custom stroke crank they can.

JRCivic1

You could use a B16 crank in a LS/Vtec sleeved block bored to 84mm, use a B16B sized connecting rod, and an off the shelf 30mm install height piston and be OK... the piston would sit in the hole about .030", but it would work. Custom pistons with an install height of 30.5mm would get you nice and safe at around .010" from the deck surface, but there would be some added cost as stated above. I am unaware of a company that makes an aftermarket rod for the B16B application, and the stock rod will not handle monster power, so all of this talk may be moot. So the real question you have to ask yourself is "If I spend all of this extra money to de-stroke a 2.0L LS/VTEC, what will I get ??? The answer would be reduced side loading of the pistons due to the better rod ratio, and depending on whose theory you buy into, likely similar power to mainstream modern Honda big displacement builds at a higher RPM... all else being equal.

Interesting path... I would watch and see what happens.

LightningTeg

That evo video is so sped up lol.

GrantMC2

Interesting reads in here .. Learn something new every day!

wantboost

iTrader: (2)

Tepid turns his GSR to 11k all day with no issues. Nothing fancy with the setup either, just proper assembly, quality components, and proper tuning.

Plus he probably has the longest surviving precision turbo I've ever seen on a Honda application.

As stated unless there's something in ruling that won't allow it there's not much point in going undersquare unless you're trying to make sustainable high rpm power. But remember that most people don't even need to make power that high in the rpm range unless you're doing something off the wall.