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Turbos and compression

TomN

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Nov 21, 2011
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You will get better answers from a actual Honda source.
There are some really good Honda people on tamparacing.com

If its going to stay with the high compression I would build it as such.
It would help to know exactly what is done to it now. I assume it's a B16a DOHC vtec motor?
It would benefit from a cai, header, exhaust, cam, cam gears and tuning soft ware like hondata and something to control the vtec.
Then nitrous.

If he really wants to turbo it then pull the motor and sell it and get one built for boost.
 

mitsuturbo

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1) I'd start with a better platform.

2) $2000 is VERY cheap. My turbo and manifold setup alone cost that much.

3) My transmission was more than that. You think a stock piece of sh*t honda tranny is going to hold up to double or triple the horsepower it was built for? I doubt it.

4) Stop trolling.
 

JNR

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Trolling?

While he asks a lot of questions, it seems to be honestly done for knowledge and we can't all be so elite in our understanding, as some people here try to be /ubbthreads/images/graemlins/uhh.gif
 

James

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Isn't the b16a one of the best Honda starting platforms?
Why should a LOW END STOCK TURBO setup cost more than 2000? I just listed all the parts and prices
And who's making double or triple stock power?
 

TomN

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I would say the K20 is better but I don't believe it fits with the stock hood.
Next up would be a B18c5. I'm not a 100% on that. Just going off memory from some Honda guys I new several years ago.
 

mitsuturbo

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Quoting James:
Isn't the b16a one of the best Honda starting platforms?
Why should a LOW END STOCK TURBO setup cost more than 2000? I just listed all the parts and prices
And who's making double or triple stock power?



Let's try 45 seconds of research and some simple math.

USDM CRX - 58 to 108hp, depending on model/engine (stock)
Civic Si - 160hp + higher compression pistons + boost = over double stock USDM CRX HP
 

James

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If he doesn't have a CRX engine or tranny, how is the CRX factory HP at all relevant to the conversation?
 

James

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And TomN is right, the b18 is the one easily swappable motor that is better than the b16, it's about a 15hp difference.
 

DR1665

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Here's the way I see it. Both higher compression ratio and forced induction increase cylinder pressures. Increased cylinder pressures require increased diligence with regards to tuning in order to prevent detonation and the death rattle of gearhead hopes and dreams.

A higher compression engine is more mechanically efficient. It stands to deliver better fuel economy and performance out of boost while accelerating the transition into boost (reducing lag). It also starts you off that much closer to the edge.

There's plenty of support for running low CR and big turbos. Personally, I think that's just sloppy, and primarily for people who want peaky, top end power at the cost of low- to mid-range because drag race car (that I drive to work and school).

Theoretically, a higher CR engine will make the same amount of power with a smaller turbo or less boost pressure. Theoretically. As with anything else in life, it's a question of goals and compromise. If your buddy is prepared to invest in serious tuning - this means more than a damned SAFC - and willing to accept the increased risk of popping that Si lump with too much boost, then I say go for it.

Just don't forget Mod #1 is strategy/mental. How will this car be used most often? How easy should it be to live with this car?
Mod #2 is tactics/physical. How much performance is directly related to driver skill? Practice, practice, practice.

$2000 is a decent budget for a turbo car. Properly thought-out in advance, combined with consistent maintenance and regular practice, $2000 stands to go further than many people these days would think. The guy who can drive $2000 in mods at 11/10 is going to be faster - and have more fun - than the guy who can only drive $4000 in mods at 7/10.

All that said, I think the CR on this Honda is a bit high for turbo, especially the way VTEC gets jiggy with timing. I don't think I'd go much higher than a 14B (I have a Subaru 13G I'd let go for $100, by the way), and I'd definitely have on-board wbO2 and a solid tuning platform like Hondata or MegaSquirt in place - and know how to use it - before I'd start shoveling boost down its throat, all FIRE IN THE HOLE at every green light.

I am no expert, but I can tell you 2GNT DSMs (with the Chrysler 420A engine) run 9.6:1CR from the factory, with cast (hypereutectic) pistons, and see 175-225psi if healthy. Hundreds, if not thousands, of people daily drive these engines with Hahn Race Craft S16Gs pushing 7-10 intercooled PSI for years without problems - and without much in the way of tuning. There's even a 2GNTer running 16:1CR all motor, which pretty much everyone on the forums would say is flat out impossible.

Every car is different though, and while there are those in the 2GNT community now running 10.5:1CR and boost (I had planned on being one of them before I moved to a GVR4), your mileage may vary.

Closing thought, though. One of the more popular budget mods for a 4G63T is to install the 2G piston/1G rod combo. Why is that? 2G pistons increase compression ratio, making the engine more responsive. Forums are great sources of information, but times are pretty tight and fewer people than ever are pushing limits or experimenting like back in the golden days of the DSM.

This place, like most others, is a great place to learn about how things have been done in the past. If you want to do something new in the future, tap these voices, consider the wisdom of experience, but plot your own course. A whole hell of a lot of engines were turned to scrap getting us where we are today - all of us. We aren't going to go much further without popping even more.

Do your homework. Plan for the worst. Expect the best.

Go fast with class. Press on regardless.
 
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James

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Thanks for that. I'll let him read it. I've sourced him to a few different threads and posts so he can try to make an educated decision.

The car is his daily, he drives it every day. He likes to get on it quite often do he would need a pretty conservative / safe tune. Ill tell him about the 13g also! Thanks
 

mitsuturbo

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Quoting James:
If he doesn't have a CRX engine or tranny, how is the CRX factory HP at all relevant to the conversation?



No mention was made of an upgraded transmission. The initial post sounds like someone is taking a bone stock CRX, dropping a modified Y2k Si engine into it, and adding a turbocharger.

I've seen stuff like this done on the cheap. They called it a "JYT setup" or "Junkyard Turbo project". It didn't last very long, but it performed ok, i guess.
 

James

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Pulled some of the motor apart today, he already has skunk2 stage1 tuner cams. he's sourcing a prelude TB and getting a 4-2-1 header... See where he's at after that
 

LIV4PSI

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That's sound like a much safer direction to go with a DD. More fun with no cost to reliability.
 

James

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And after doing some research the motor is actually a b18.

So we've got a b18 motor/trans, skunt2 coilovers, unknown brand clutch but it grabs like a monster, high comp pistons, stage1 skunk2 cams, front and rest strut bars, CAI, cat back exhaust. Next is 4-2-1 header, wife and an oil pressure gauges, Hondata and tuning.
 

JNR

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Isn't the "4-2-1" a Tri-Y header? Guess I haven't heard that term before, but picturing what that looks like (a tri-Y).
 

TomN

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Never heard the term tri-y before. I've always heard 4cylinder performance headers for a car or bike called 4-2-1 headers.
 

TomN

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Quoting James:
And after doing some research the motor is actually a b18.

So we've got a b18 motor/trans, skunt2 coilovers, unknown brand clutch but it grabs like a monster, high comp pistons, stage1 skunk2 cams, front and rest strut bars, CAI, cat back exhaust. Next is 4-2-1 header, wife and an oil pressure gauges, Hondata and tuning.




Is it a B18a/b or a B18c?
 

JNR

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Quoting TomN:
Never heard the term tri-y before. I've always heard 4cylinder performance headers for a car or bike called 4-2-1 headers.



Interesting, maybe the 4-2-1 must be a newer import term then...They've always referred to them as Tri-Y (4 or 8 cylinder units, and even sometimes on oddballs, like 5, 6 and 10/12 cylinders) when you have a row of four cylinders, with two of those cylinders going into one tube, and then both of those 'joined' tubes merging into one common tube/collector...Basically, you have three Y's then on a header and hence the name...Doug Thorley used to specialize in that design, but there were other manfacturer's....it enhances low and mid range torque mostly, provided you are using a smaller primary, etc.

"Regular headers" are typically referred to as "4 into 1" and of course you have some sub-names within those, like shorties, long tube (more modern term), equal length, anti-reverberation (stepped) and so on.

FYOI - do a search under Tri-Y and you'll get all sorts of hits and info /ubbthreads/images/graemlins/smile.gif Basically same thing as a 4-2-1, of course, so it comes down to what somebody wants to call it. Just sounds weird calling out the #'s IMO and can cause confusion to a 4 to 1, so probably why they coined it as tri-y.
 
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TomN

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First time I ever heard the term 421 header was in the mid 80's when I first got into bikes. May just be a location thing. Never heard anyone refer to it as a tri-y down here. Lots of names for the same part though.
 

JNR

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Definitely and same here, as far as hearing the Tri-Y term back in the 80's (want to say it went back t the 60's with DT and want to say sanderson (?) and some other old mfr's)...doesn't really matter what we call it, as we know what it is. I just wanted to make sure it was the same thing with that term (and not meaning 4 into 1), as they are two different designs and change the characteristics differently.
 
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