Getting built.....

[honura]

Ok here we go.......... I cracked a sleeve on my current block so i picked up anoher and i am going to build it up a bit. here is what i have so far. ls wiesco pistons i think 8:5 std 81mm bore ls eagle rods arp head studs itr head and intake manifold fidonza flywheel 6 puck clutch kit 680cc injectors catch can chipped p28 walbro 255 now ?? stock or acl race bearings stock head gasket or cometic this will be in a 97 civic coupe with a full greddy turbo kit running a 18g/td05 turbo i would like to be in or around 400-450whp is it possible ?? THANKS FOR THE GUYS!!!!!!

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[94c1v1cex]

need to get oversize pistons like 81.25 or something... and higher compression. your gas milage is going to suck. bigger injectors would be a good cushion. either bearings or headgaskets are fine. stock honda you can still use at 81.25mm bore.

[BlakeJ53]

Whats wrong with low compresson like 8 to 5 or 8 to 8. Many many companys like sabb crysler and many other use a 8 to 1 compression piston. Vitaras are 7 to 5 to 1. You can push pump gas farther on low compression.

[redlinetuning]

I'm at 9.0:1 on 81.5mm CP pistons (B16A)... and yes.. mpg sucks. I'm running both ACL main&rod bearings and a .053" cometic hg. no problems yet.

[honura]

why do I need a bigger piston? Just gas milage? I could care less about that. this is what I have. I'm broke and I need to use what I have lol. Is there a major diffrence between the cometic or stock head gasket?

[GT35R_EF]

You don't NEED to buy higher compression pistons. If you have it, run it? Your partial throttle won't be as good, but if you don't care than no one else should lol. Your horsepower goal is possible I guess, but you're going to have to push that 18g pretty hard. Don't worry about the injectors if you already have the 680's, just push them until you can't get anymore and if you're not happy, give it some time and pick up bigger ones. Run the OE headgasket and bearings are your choice. Good luck, sounds like you got most of it figured out.

[94c1v1cex]

Originally Posted by BlakeJ53

Whats wrong with low compresson like 8 to 5 or 8 to 8. Many many companys like sabb crysler and many other use a 8 to 1 compression piston. Vitaras are 7 to 5 to 1. You can push pump gas farther on low compression.

do you have any idea what you're talking about?? wdf is 8 to 5? or 7 to 5 to 1?!?!

its 8.5:1 and 7.5:1 that low of compression is just stupid you'll have no power unless you're in boost. it'll be sluggish as shit and annoying to drive around.

yes you can make more power on pump gas with lower compression but you'll have to run a ton of boost to it which is more strain on your motor... so why not be smart and run at least 9.5:1 and have decent low end power and better gas milage?

to the OP:
you need bigger pistons because with the stock sleeves your piston to wall clearances will more than likely be too great and you'll get piston slap.

golden eagle just takes oem honda headgaskets and laser cuts them... oe honda gaskets are fine. used one on the shop car... made around 8-900.

edit:
i didnt even notice the 18g... i doubt that turbo will make that much power efficienty espeically on 8.5:1. you'll need to upgrade

[Running925]

carma

[redlinetuning]

Originally Posted by 94c1v1cex

to the OP:
you need bigger pistons because with the stock sleeves your piston to wall clearances will more than likely be too great and you'll get piston slap.

Not necessarily, it all depends on the condition of the cylinder walls. Properly honing good cylinders will not take enough material to open the piston-wall clearances that much, especially if the motor is in good condition and hasn't been honed since the initial Honda factory assembly. You'll need to check the piston-wall clearances regardless.

OP: 8.5:1 compression ratio is pretty darn low, so you won't make much low end power/torque, but with a bigger turbo, you'll make plenty high end.

If you do get Cometic, just get a stock thickness. With 8.5:1 compression, you won't need a thicker hg. Doing so will only lower your compression more. Either is fine.

[rustydusty1717]

400 WHP on an 18g might be capable, but you will be pushing it hard. 450 WHP on an 18g is not even possible.

[BlakeJ53]

I can run off atleast a list of atleast 3 cars makeing great power with low compression pistons. 2 of whitch are Vitara setups and they are 7.5:1 compression. The other is a 8.8:1 84mm gsr that is close if not over 600 on pump and all of them cut mid 10's in street trim. Here is proof:http://videos.streetfire.net/video/S...htm#commentTop

[marcj]

9:1 is optimal in my opinion.

[TheShodan]

Originally Posted by BlakeJ53

Whats wrong with low compresson like 8 to 5 or 8 to 8. Many many companys like sabb crysler and many other use a 8 to 1 compression piston. Vitaras are 7 to 5 to 1. You can push pump gas farther on low compression.

This type of thinking is rather limited for a number of reasons:

1) Turbocharger efficiency matched to static compression - Saabs/chryslers and other OEM platforms that are that low of a static compression have a different goal than enthusiasts; the purpose was for the average driver to be able to drive the car anywhere in the world and not have to worry about ROM octane requirements. From 87-100 octane, the car would operate normally. These turbos are also MUCH smaller than what most users here will use because the purpose of the turbo for the OEM is different. It is to help promote fuel efficiency and up front low end torque. This is something that is highly desired in daily driving commuting purposes, not for racing. The turbos used are only about 35-40lbs/min MAXIMUM for its efficiency. Most people that use from 50 "trims" to 61mm compressor wheels will range their volume of air flow rates anywhere from 48lbs/min to 65lbs/min; far different than what the OEM had in mind with such a low static compression.

The efficiency of the turbo used with such low static compression will be out of its range creating bad off-throttle and off boost response, while at the same time requiring more boost pressure (hence more useless internal heat) to gain the same power. The only advantage is that tuning does not have to be accurate in order to work.... to a degree.

2) Effective compression & Static Compression. Whether it is 7.5:1-10.0:1 static compression, cars for a given power level have to reach a particular effective compression; that is the compression that the engine actually sees when it is under full load while driving. yes, using ultra low compression was the standard when precision tuning for imports were not available, but in 2009, there are a multitude of choices that a honda owners can use to accurately tune with a much higher compression, and at the same time keep the off-boost acceleration that the N/A car has, and works well with 93 octane.

For those that want to brag about how much pressure they use to run the car, going with such a low static compression is an option, but I'm sure that the user would rather have a quick accelerating car with low boost pressure and leave the bragging to the DSM guys who need tool kits in their cars.

Try not to compare the OEM to an aftermarket turbo setup, it's like comparing apples to cantelopes.