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which pistons (help Tuan)

1194 Views 3 Replies 3 Participants Last post by  mystical
I own a 99 GSR. have done a few upgrades, but I am ready to go faster.. few of my upgrades. AEM fpr,AEM fuel filter, AEM fuel rail, DC 4-1 headers,AEM CAI,NOS plate system 125 shot right now.etc. I am ready for some internal work. I want to do the following: piston & connecting rods,
camshaft, valve springs, valve retainers, I am also adding a F-max turbo. my quesstion is should i go with crower, jun, spoon, or jg. I am having a hard time deciding who to go with. (money is no option). Also what compression rates on the pistons since i will use a turbo..

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well, looks to me like you don't know what you want to do. if you have nitrous, build up your motor for nitrous, if you want to go turbo in the future, plan ahead and do it. but looks like you are confused and want to go turbo/nitrous and all motor. i say this becasue it's really hard to try and mix a turbo and nitrous on the same car. unless you are a rich bastard, you will blow many motor with nitrous and a turbo.

Tuan said:
it's not uncommon to use nitrous as a way to cool the turbo boost before it enters the combustion chamber.

If you want to compare pistons, you must first determine the boost you need to get the hp you want (with the necessary factoring in of pressure added by an intercooler and the effect of temp cooling by nitrous). BTW you don't need 125 shot nitrous with a turbo running 9-11 psi boost to cool down the charge.

I think the actual amount of nitrous plays a realtively small role , once boost has been added to making an incremental increase in of diminishing returns.

once you determine the amount of nitrous that will give you the added gain in power on top of the boost you want (50 shot may give you as much as 125 shot once boost has been added), then you select the CR you want to allow that much volume to be shoved into the chamber safely.

it's a trade-off. you add too much nitrous to the boost and the increased temp/pressure inside the chamber will risk more detonation depending on how well atomized the fuel is added and how much fuel is added. So to get a little more at the cost of a huge risk increase in detonation may not be worth have to work out the numbers in detail.

comparing forged pistons, you have to look at the amount of surface area added by the piston top. More surface area reduces the chamber temperature and slows the burn rate and decreases burn efficiency regardless of CR.

if the dish is deeper on one piston compared to another for the same CR, then you have MORE surface area. You don't want that. Some manufacturers give you the lower CR you want without deepening the dish...they reduce the compression height (side profile view of the piston, compression height = distance from the piston pin center to the top of the piston) instead. Just make sure they give you enough top piston ring clearance to the top of the piston for boosted applications.

Weight savings (from using different alloys), larger piston pin diameters (bigger diameters are better), oil drain hole locations, use of free floating rod bushings, a reputation for tight fit to spec, ring end gap, heat coatings on the piston top, low friction coatings on the skirts, and piston skirt length (longer ones rock less as the piston travels up and down) are some other differences you may want to compare when you are shopping.

I see no reason why you should fork over more cash for titanium pistons to get lighter weight and heat resistance. Titanium is an aggressive metal that likes to grab other metals and wear them down faster. Surface incompatibilities are an issue the ti manufacturers don't tell you.

So work out the numbers you need for boost to determine CR you need and then compare the pistons that have that CR using the list of design features to compare...choose the one with the most goodies at a good price.
Hell yes this is what SHO needs, Tuan, you da man!!! man i miss that shit, i use to be TEALBANDIT94:D ;)
Thank you for the inputs.....

I will take the red pill.
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