bowtieboy911

i need to get a new front mount and piping and its gonna be going on my 2000 honda civic si...sleeved and bored to 84mm, wiseco pistons, eagle rods, acl race bearings, all new valvetrain, and skunk2 pro1 cams, i have a 57trim precision turbo...i plan on running 15lbs+ at least and good for at least 450hp but i have heard run 3" piping and i have heard run 2.5"? can someone please help me out here?

TheShodan

iTrader: (14)

2.5" is more than fine for over 650whp.. keep it simple.

MR.johnson

2.5 is fine. but if you want to make more i would just build 3'' and never mess with it again.

kyden

use 2.5". but just to note i would ditch the pro1 if you're using a "57 trim"

rich7777

Would there be any downsides to running 3" over 2.5" if it wasnt needed ? Would you be sacrificing any bottom end power that you would gain up top ? i.e. would it hold boost better at the top of the powerband.

BigMike0147

It could actually hurt you to run too big of intercooler piping (from what i hear). It could help spool time slightly to have smaller piping because it's a smaller volume to fill with the compressed air. I read that somewhere, but it makes sense to me.

rich7777

Mac, can you input please.

lsturbo33

If your using a 57 trim and your goal is 450 then you should probably switch to a different turbo. If it's a street car I would use 2.5" with your power goal.

Schister66

Running piping that is too large for your setup will increase lag time and decrease power numbers since the air charge is moving at a slower pace through the larger diameter piping. If you read through the Forced Induction FAQ, there is a thread (that i compiled) about how to calculate your correct intercooler piping size. For a 57 trim, i dont think you'll need anything larger than 2.5"

bowtieboy911

yeah i plan on eventually upgrading the turbo but i just paid for all the motor parts and the labor for the machine shop but i mean intercooler and piping isnt too expensive compared to a turbo so i figured i would get all that stuff before the turbo and i am kinda trying to build it to be streetable but also where i can take it to the track for the hell of it...but for in the future what will be a good turbo? and im not looking for the highest hp i can possibly get i would like to get one that will still spool up quick and not all for top end and racing all the time cause like i said i would like to drive it on the road on nice days. thanks

bowtieboy911

do people run smaller than 2.5" then if smaller is better?

bowtieboy911

what about wastegates and bov's why do people get bigger ones and some people use the smaller ones will too big of a wastegate or bov make you lose power?

Schister66

^There are many instances where people should be running smaller than 2.5" piping, but with Honda setups, you rarely see someone do it. One thing you'll notice about Honda FI is that people buy parts that tend to be a little too big for their setups...be it an oversized intercooler or a turbo that's two sizes too big. I think you'll be fine with 2.5" piping, but in the future if you decide to upgrade and push past 550-600whp, it may be time to consider upgrading to something larger

bowtieboy911

i mean i do plan on hitting the 500+ mark soon.. i mean its already sleeved and complete build but i mean i would like to buy what i will need in the future when i reach my hp goals so i dont have to rebuy the same **** like intercooler and pipes and **** ya know? so idk if it will cost me a couple hp now i would rather do it then when i go big ill already have what i need...?

LS AzZkIkr

I have a friend that switched his setup from his civic hatch to his integra and he had to make new charge piping. He decided to sell his 3" from the civic and make new 2.5" for the integra and got a re-tune. It picked up more mid range and actually more on top end due to the turbo spooling faster for some reason! I rode in both cars and the integra is definitely a better all around setup. I am only assuming that the change is size is why it is better because that was the only change to the motor.

DelSolMarine

2.5" piping is perfectly fine... guys are making over 700whp with 2.5 charge piping... 2.5 inch piping measures 63.5mm... if you have 3 inch charge piping which is 76mm going into a 63.5mm throttle you are going to be creating a bottle neck at the point of entry... (essentially)

4cylfiend

iTrader: (1)

THIS!

DelSolMarine

what you meant was ditch the 57 trim since the OP has stated he has a fully built motor...precision journal bearing ftw... just my opinion

4cylfiend

iTrader: (1)

lol no I was agreeing with what was said. Ditch the pro1's if the op is sticking with the 57trim precision. The pro1's arent meant for turbos smaller than a 35r. I ran pro1s last year on my pte 5857 and they didnt do a thing. Im running a 6262 this year. In agreeance: Precision FTW!

DelSolMarine

thats like a breast reduction! why go smaller when you can go bigger!!!!

im running pro1s with a 6265 which i love thats why i comment...

OP- what are you goals? 450whp on pump gas? the different size wastegates are based of an individuals setup.... typically the large wastegates are going to control LOW boost more efficienty than the smaller wastegates when using a larger turbo however the location of the wastegate is just as critical.... typically you see people with a gt35r or larger turbo running atleast a 44mm tial for example and depending on their manifolds flawed design (like my garbage peakboost manifold) will see excessive amounts of boost creep... i am personally and unfortunately unable to run less than 13psi with a 9psi spring on my setup because of the inefficient wastegate placement on my turbo manifold... hope that helped... i would also recommend reading/searching on these types of questions more lucratively because your not going to "dot all the i's and cross all the t's" as well by just asking the questions on the forum.

golf-mk3

idk if anyone has toughts about this. but a 57 trim has a 2" outlet. so why not 2" to the intercooler then 2.5 to the tb.

DelSolMarine

he said earlier he plans to upgrade his turbo in the future when he is financially able to do so...

Muckman

iTrader: (2)

Match the inlets and outlets of your components. If you have a stock 2.5" TB then theres no point in running larger piping. Same if you have a E cover with 2" outlet.

4cylfiend

iTrader: (1)

If this is the case then stick with the pro1s!

bowtieboy911

but yeah for the people who havent read what i said earlier i figured i would go with the pro1s then later on when i get the money i will be upgrading my turbo...not sure which one? (any opinions) and i have never seen any problems with all the precision turbo's i have seen so its all opinionated i guess but i mean i like garrett, turbonetics, borg..but like i said im not looking for just a race setup and all top end at the moment thats why i chose the pro1 cams its kinda in between... i was looking into the pro3's or toda vtec killers before i chose the pro1s but too agressive for me