Fmic Piping Size

[dethatch]

stock rb25det (have not put the apexi pfc in yet) small fmic (not sure on the metric conversion but it is 27in x 3" x 10") 2.5" outlet. I figure its better than the factory side mount from the r33 but do I need 3" piping or is the 2.5" okay?..My thinking was a smaller fmic meant more flow pressure and larger meant less flow pressure and larger would be all out race. I guess you can look at it from many different angles and usually bigger is passed on as better but not always the case. have a big cam and a small head no purpose..put a turbo on a high compression engine..no boost..so I figured small fmic for a stock rb25dett..Im not really sure what kind of power to expect as this is my first try at this style car and engine and first turbo for that matter too. I do have a pfc coming soon in the mail and I am sure that will make it have more pep but shouldnt outgrow the small fmic until I add a larger turbo and go top mount and front facing intake..right?

thanks for the time....just learning

[TiTAN]

2.5" piping will be fine and it will still be fine at 300kw.

[gotRICE?]

.put a turbo on a high compression engine..no boost.

I realise you said your learning, but what exactly would you call high compression?

VTEC hondas have relatively high compression, and a friend of mines 1800 Civic makes 317fwkw on 17psi. Compression is still 10.5-1.

[juggernaut1]

I spoke to Richard are A.R.E. once on piping size on the intercooler outlet.

As a guide, 2.5 inch on the cooler outlet up to around 400rwhp and 2.75 inch approaching/from 400rwhp as the 2.5 inch starts causing a restriction.

Edited December 3, 2009 by juggernaut1

[wlspn]

Have to agree with above. A high-compression NA motor will still make boost & GOOD power...

If it wasnt for the fact that higher compression motors with boost added are prone to detonation we would all have 1

[dethatch]

Have to agree with above. A high-compression NA motor will still make boost & GOOD power...

If it wasnt for the fact that higher compression motors with boost added are prone to detonation we would all have 1

more compression less combustion chamber to force air into

[dethatch]

more compression less combustion chamber to force air into was what I was referring to..and when I refer to high compression its from my v8 ford days with a 408 stroker running 13:1 had to run 114 octane premium fuel only and only could run for 25-30 minutes max before the ping started.., thanks for the replies, answered my original question..I am learning so thanks for all the replies! very helpful!

[XRATED]

John, where in the states are you?

I've run 2" from turbo to cooler to throttle body with great sucess in the past... the little rb20 was running around 380bhp. The smaller cooler pipe work helped reduced the transition time from off boost to on boost.

J.

Edited December 3, 2009 by XRATED

[dethatch]

John, where in the states are you?

I've run 2" from turbo to cooler to throttle body with great sucess in the past... the little rb20 was running around 380bhp. The smaller cooler pipe work helped reduced the transition time from off boost to on boost.

J.

I live in North west Louisiana Shreveport wow..380 bhp my goal is in that range.

I will put some pics up soon..waiting on a few parts.

thanks again guys.

[XRATED]

The cooler had 2" inlet and outlet too... It was a marked improvement over the 2.5" into 3" pipe work and huge cooler that had been on there. I downsided to try and pick up some transition time and also to allow more air to flow to the radiator.

280rwkw is a good number for a 25... With the right turbo choice, it should still be nice and responsive. Try a precision turbo 5557 with the billet comp wheel and t04e comp housing.

[dethatch]

nice..280 rwkw translates to just under 400hp at the wheels (375 or so). I had 290 rwkw (390hp) dyno'd in a 2900 lb car (small s10 truck) and it ran high 11 low 12 second passes all day with moderate wheel spin..If I can get this rb25det to pull those numbers at the wheels I will be very pleased. not to mention I should be around 2600 lbs in the Nissan..good stuff thanks!

[XRATED]

I saw an awsome s10 at moroso a couple of weeks ago. Very neat with a set of slicks and a quiet, turbocharged small block... ran 9's all day and pulled wheelies to the 60ft mark!

what did you have in the s10?

Is the 25 auto? My numbers were made with a manual trans.

[dethatch]

I saw an awsome s10 at moroso a couple of weeks ago. Very neat with a set of slicks and a quiet, turbocharged small block... ran 9's all day and pulled wheelies to the 60ft mark!

what did you have in the s10?

Is the 25 auto? My numbers were made with a manual trans.

I got mine with a 5 speed also

s10 had a 350 chevy with a 283 steel crank downstoked to 302 cid could make almost 8500 rpm afr heads custom intake powerglide..solid motor drank a ton of gas..done with all that now outside of my restorations and restomods will be nice to lay down that kind of powr in a 6cyl turbo car that is basically a sleeper.

where you located?

[XRATED]

Thought so...

Your 240's going to be much more fun than the s10, but it won't be as fast down the quater. It's hard to beat a v8 and a big auto for a quater run.

[dethatch]

Thought so...

Your 240's going to be much more fun than the s10, but it won't be as fast down the quater. It's hard to beat a v8 and a big auto for a quater run.

not sure about the not as fast part down the 1/4 prolly will never be competitive just fun if I take it to the track ( I really hate doing drag with a stick) but I have seen these conversions tear a newer model cobra mustang up on the street and i have not even considered spraying the inter cooler yet. At the track the bee-r should help off the line if I ever got serious..just want a good old fashioned sleeper for the street...just found out the closest shop to tune with the power fc is like a 5 hr drive from here..geez.

[SLAPS]

Mine made a shade over 300rwkw with *GASP* 2" piping and a 90mm bar/plate that used the std piping route. A decent set of cams opens the old rb30dohc up.

There was a fair pressure drop but she still made the power

Edited December 4, 2009 by SLAPS