Loosing power when engine warms up! - Honda Forum / Acura Forum

boostedb · 02-08-2008, 02:45 PM

i was wondering if anyone can tell me why it seems im loosing a considerable amount of power once engine gets good and warm. it seems as if it is bogging out. the engine is rather new its a jdm b18b in a civic. i had the same problems with old engine which has 300,000+ miles be4 it spun a bearing. I just assumed it was the old engine but now that the new one is in it is still doing it. i was also wondering if haveing the lil piss ass civic radiator is the problem but the temp gauge reads fine...also the last engine ran on it for a looong time.. any help would be apprciated

soldiermanny · 02-09-2008, 07:49 PM

Quote:

Originally Posted by boostedb

i was wondering if anyone can tell me why it seems im loosing a considerable amount of power once engine gets good and warm. it seems as if it is bogging out. the engine is rather new its a jdm b18b in a civic. i had the same problems with old engine which has 300,000+ miles be4 it spun a bearing. I just assumed it was the old engine but now that the new one is in it is still doing it. i was also wondering if haveing the lil piss ass civic radiator is the problem but the temp gauge reads fine...also the last engine ran on it for a looong time.. any help would be apprciated

did you have that 3" exhaust when you had the old motor? idk, but that exhaust is too big for your settup now and could cause you to lose power. if you were boosted then it would be a different story.

boostedb · 02-11-2008, 03:06 PM

Yes it put on the car before i purchased it. i know that the 3" exhaust is hurting me but should it be making that big of a diffrence? and if so why only when the engine is warmed up? the only reason i havent changed it is because i have been slowly gathering parts to boost it. i have a garett t3/t4 turbo, and a greddy piggyback. still waiting on few other peices ( manifold, injectors... etc etc.) so i haven't wanted to spend cash on changing the exhaust just to change it back once i have all the parts... do you think thats where im am loosing my power? and if so why is it only after the engine warms up? should i spend the money and get 2 1/4 in exhaust for the time being? my income has slowed down so getting turboed may take longer than i expected.

soldiermanny · 02-11-2008, 07:47 PM

Quote:

Originally Posted by boostedb

Yes it put on the car before i purchased it. i know that the 3" exhaust is hurting me but should it be making that big of a diffrence? and if so why only when the engine is warmed up? the only reason i havent changed it is because i have been slowly gathering parts to boost it. i have a garett t3/t4 turbo, and a greddy piggyback. still waiting on few other peices ( manifold, injectors... etc etc.) so i haven't wanted to spend cash on changing the exhaust just to change it back once i have all the parts... do you think thats where im am loosing my power? and if so why is it only after the engine warms up? should i spend the money and get 2 1/4 in exhaust for the time being? my income has slowed down so getting turboed may take longer than i expected.

its deffinetly your exhaust. its just way to big. have you ever heard of flow velocity? well to make it simple, its the velocity of your exhaust gases exiting your exhaust system. you have a certain amount of air entering your engine, then goes thru the combustion chamber then the faster you get those exhaust gases out of there is how you make power. when you have to big of an exhaust you have expansion, the gases move around more rather than exiting straight out the piping. thus slowing down the flow. thats why correct pipe size is important. so a turbo motor would need a bigger exhaust system because its sucking in alot more air and needs it to exit quicker. but in your case, you dont have enough airflow to have that big of an exhaust. and as for the warm up period you talk about is probably because you run richer at the time so your engine is sucking in more air than normal to get the correct air/fuel ratio and your exhaust is helping out a little. then when your all warmed up and your engine idles normally is when you lose power.

boostedb · 02-12-2008, 11:20 AM

thanks for the info. i knew it was hurting me.. i just figured it was because i have no back pressure with the 3"... im losing in the low end (which with a b18b thats where u get most of ur power very torquey) ,and gaining a little in the top end... but seeing as this is my daily driver.. im not always wide open throttle. im putting extra strain on my engine. i guess ill put buying the rest of the parts needed for boost on hold and work on getting a new exhaust system and just try and save the old exhaust to save $ later down the road.

Once again thanks for the info. very helpful.

soldiermanny · 02-12-2008, 01:07 PM

Quote:

Originally Posted by boostedb

thanks for the info. i knew it was hurting me.. i just figured it was because i have no back pressure with the 3"... im losing in the low end (which with a b18b thats where u get most of ur power very torquey) ,and gaining a little in the top end... but seeing as this is my daily driver.. im not always wide open throttle. im putting extra strain on my engine. i guess ill put buying the rest of the parts needed for boost on hold and work on getting a new exhaust system and just try and save the old exhaust to save $ later down the road.

Once again thanks for the info. very helpful.

no prob...

98B18BTeg · 02-13-2008, 04:47 PM

Backpressure is an enemy. But the proper exhaust for you application is your friend. I did not see you mention if there was a CAT on the exhaust. If so, check that out as well.

boostedb · 02-13-2008, 04:54 PM

dood... idk what the hell you are talking about.... maybe for v8s back pressure is bad... but 4 bangers need some back pressure. also read my car info.. it says Testpipe (aka no cat)

sc15 · 02-13-2008, 05:33 PM

3" is good for turbo. actually perfect size if your turboed. make sure your straight piped though, no converter. if you keep the converter your car smells like egg when on idle and sounds ugly and slows you down. my car usually goes slow when it's cold, not warm.

mattliston · 02-13-2008, 05:33 PM

back pressure is needed, take a look at this http://www.nsxprime.com/FAQ/Miscella...austtheory.htm
very informative, tells you why exhuast diameter and other factors need to be taken into consideration. Good luck with your build!! Im hoping to piece together a turbo for my ef with 200k on the engine, hell yeah!!! still running dpi, but in process of buying and swapping in a mpi from an Si, know anyone....?