Modify the stock engine?

[skate1968]

Hey Honda fans,

I've got a 91 Civic DX with the stock 92 HP D series. The car has no rust in the wheel wells, nor the undercarriage.

I want more power but a swap is looking a little pricy right now. How much more horsepower would i get from an aftermarket, 2.5" or 3.0" or whatever, exhaust system? 10 HP?

How much more horsepower would i get from an aftermarket exhaust combined with a cold air intake? 18 HP?

[18HP increase on a 92HP engine is not fantastic, but i'd imagine i'd enjoy the boost]

It seems like after market exhaust would be a smart investment for now. Because if i ever decided to modify or swap the engine I'd still recieve benefits from the exhaust afterwards.

I imagine that a free flow exhaust would NOT help gas mileage. Are there any other down sides of such modifications of your engine? Would such mods necessarily cause increased pressure and engine wear?

I'm just trying what i should pay for now and what i should save up for.

Thanks

[Clutchmaster]

do intake header and exhaust I'd go no bigger than 2.5 a decent muffler and you should have fun with it

[skate1968]

Thanks! :D

[Infamous]

Gains will be more around 8-10hp total. No need to go over 2.25in exhaust, 2.5 will peak higher but not gain as much as 2.25 throughout the entire RPM's.

[94lxcivic]

i'd reccommend swapping the intake manifold to mpfi. you'll see gains all over with that swap.

[ryan89crx]

i would NOT go bigger than 2.25" on a n/a D. especially a stock 1.5L

you are going to lose torque and overall be unhappy with the performance

[eg4]

I would use 2" on an d15

[RandysSOHC]

I've got 2" exhaust with a 1.5,
swapped to mpfi & you'll have some e/t times like me :p

well..........maybe

[guest]

why the hell is this in engine management????? people take it so easy on noobs here......

[goomer416]

well you can get a z6 for real cheap... i got mine for $200 cnd and with 90,000km
they r considered a throw away engine... and they swap right in... all ive needed to buy is a p28 ecu and coversion harnesses dpfi - mpfi and obd0 - obd1 $250 for all
i priced it all out and ur gain is about the same if you buy an full intake and exhaust depending on the price of ur motor

[D15B]

i'd reccommend swapping the intake manifold to mpfi. you'll see gains all over with that swap.

i agree. do that 1st b4 doing intake n exhaust.

[ddd4114]

How much more horsepower would i get from an aftermarket, 2.5" or 3.0" or whatever, exhaust system? 10 HP?
I say 2.25" max, and the gains depend on the design on the exhaust system. You could see 3hp with one, and 7hp with another. 10hp is a pretty big gain for an exhaust system on a d15.

How much more horsepower would i get from an aftermarket exhaust combined with a cold air intake? 18 HP?
If you're combining a CAI with the exhaust, take whatever number from my previous statement, and add 2 or 3hp.

[18HP increase on a 92HP engine is not fantastic, but i'd imagine i'd enjoy the boost]
Actaully, that is a pretty good increase in power (~20%)

I imagine that a free flow exhaust would NOT help gas mileage. Are there any other down sides of such modifications of your engine? Would such mods necessarily cause increased pressure and engine wear?
A free flowing exhaust will help your gas mileage. The engine can easily expel exhaust gases and waste less energy doing so. The only downside (besides the hole in your wallet) is the noise. You can get "quiet" exhaust systems (such as A'pexi's WS2), but the gains from them aren't as great.


Before you start throwing random parts on the car, decide exactly what path you'd like to take (turbo, N/A, engine swap). That way, you won't waste as much money as you would with an unplanned medley of aftermarket parts. Like what others have said previously, I also think you should do a MPFI swap, but keep in mind that takes a bit more time and skill than installing a CAI. Good luck.

[kyle h.]

I would use 2" on an d15

[skate1968]

First off, i'm sorry if i put my post in the wrong forum.

Thanks to everyone for the feedback, much appreciated. It seems as though i got some inaccurate technical information in the past.

One shop told me that a MPFI by itself would not yield enough of an increase to justify the cost. I'll shop around to see if I can find someone who can make it feasable.

[SillyImportRacer]

[QUOTE=ddd4114]
Before you start throwing random parts on the car, decide exactly what path you'd like to take (turbo, N/A, engine swap). That way, you won't waste as much money as you would with an unplanned medley of aftermarket parts. QUOTE]

That's the best thing you can do.
Figure out what your goals for the car are before throwing $$ at it.
If it just going to be a dd, then cat back & CIA might be enough.

Have fun & Good luck

[Clutchmaster]

i'm runnig 2.5" with cat and muffler and no real loss down below but then again i stay in the mid range and high RPM due to alot of Highway driving

[ddd4114]

One shop told me that a MPFI by itself would not yield enough of an increase to justify the cost.
That's probably why they said that; a shop will charge you a lot more than you should pay. If you have the time and are willing to learn, you could pull it off yourself.

[SupaStyl]

A free flowing exhaust will help your gas mileage. The engine can easily expel exhaust gases and waste less energy doing so. The only downside (besides the hole in your wallet) is the noise. You can get "quiet" exhaust systems (such as A'pexi's WS2), but the gains from them aren't as great.

not quite, i have proven gas gas recipts that have proven that the motors will get the best gas milage with header, high flow cat, and a good catback muffler system with some back pressure. Yes you sacrafice some top end power with back pressure, but you have more torque in the lower rpm.