First what engine do you have?


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I believe its a m52b25 since its a 323i e46

 

Intake = 0 (or -1/-2)
Headers = 5-7 whp
Catback = 2-3 whp
Sport camshaft (zhp???) = 2-3 whp
Tune (5 whp??)

Max possible maybe 18? So you'd go from 184 hp (assuming your car lost 0 horsepower in 15 years) to 202 hp?

Not worth it in my opinion. You'd create a bunch of noise, spend a lot of money, and still get stomped by a Camry V6

I would upgrade suspension and tires if i were you! And brakes. get some 330 brakes.

Forget the power.

 

...spend a lot of money, and still get stomped by a Camry V6.

Damn funny stuff there.

To the OP: Drive it slow and keep 'em guessing.

 

Here’s a guide on 330. Yours will be similar but only less of a gain since your motor is smaller but will cost the same. What your talking about is gonna cost a lot. You would get more hp and it would be cheaper to put a 330 motor in it. It will bolt right in and bolt to your transmission it’s a easy swap.
https://forum.e46fanatics.com/showthread.php?t=884584


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330 swap will be the most beneficial apart from forced induction

 

Probably be ahead to just sell the 323 and get a 330. They are pretty cheap I know of 4 near me for under $2700 all decent cars. 1 is a 4 dr with m3 fenders quarters and bumpers. It’s only $2100 but needs a clutch. The other 3 are nice cars with at the mileage between 130-146k. And all but the m3 wannabe have a comprehensive documented service history


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Change your differential ?

 

Just weld?

 

Don't forget Underdrive Pulley's. But I agree with most, get a 330 and then shop around and do the mods, buy used if its feasible. BTW, get a cotton free flow filter from Amazon for your stock intake. Its better than a CAI and 10 times as cheap. https://www.amazon.com/Reusable-Washable-Replacement-Drop-Filter/dp/B06XH85RW5

 

Bout tree fiddy

 

....i think most of you talk about hp in a guestimate manner! No car will benefit for no horse power as long as engine is not impaired by one of its parts. As long as your exhoust is not damaged, you wont get nothing from anything you throw on exhaust,not from cats remove, not from headers; all you get is an actual power band shift. As long as engine brain delivers same amount of fuel,on the same spark with the same valve opening/closing points and times , your power will never increase, maybe you can lose few horses. Only gain will happen if before mods, your engine suffer from vital components degrades/impairments. Different story if ecu is properly adapted to suits changes,in this case, will be gains. But on 2.5L engines dont be too hype with "xx" numbers per mod, cause you"ll never go beyound ~190whp even with major and costly changes on those engines. (~190whp is a minded m54b30 true power , so a 230bhp is a max for b25)

 

exhoust is not damaged, you wont get nothing from anything you throw on exhaust,not from cats remove, not from headers

Wait..what? Are you saying aftermarket headers do not increase whp on e46s? And only shift the power band?

With your last sentence words "possibly tune" i assure you that your research was in vain. I go over your nonce affirmation with b25 being neck to neck with a heavily moded b30 (same mods + more gains per mod + ported head + serious tune put b30 in the 220~225 zone) ,but that "maybe" for the tune....seriously ? Do you belive our cars have some kind of autotune feature ?

Re-read my post. I said my research into a B30 build. Of course a B25 will have less power potential. No where did I say a heavily modified B25 will be neck to neck with a similarly built B30. I don't know why you would think that.

Yes, our cars do have an "autotune" to some extent. The DME will adjust the fuel to match increased airflow to a certian point. It isn't at all ideal for maximum performance but it is enough to see gains in power without a tune.
Plenty of guys are running intakes, headers, exhaust etc... with no tune and still show improvements in power.
And anyone who is making the investment into cams or headwork will also invest in a proper tune and could exceed the estimate.

Not sure where I confused you.


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If somebody knows where is the map that is responsible for this fuel compensations over the whole power band when more air enters engine, please,let me know, i want to simplify tunning procedure fiddling on this map instead of fuel tables.

 

M5x exhaust manifolds are indeed poorly designed and don't allow for too much airflow out from the engine, but after unscrewing them and don't hook up too fast the new, larger, unrestrictive headers, we look a sec at engine ports.....surprise,they are as tiny as old headers holes. Do an expansion on exhaust pipes and guess what hot air do at that expansion point...,it accellerate, or it slows down ,..research this easy part. engine management is finished last in an engine development and is mainly based upon those holes,cams, even smallest bends in pipes. Any disturbances,must be corrected if we need gains. There is no restriction over a unique global exported car.

 

restrictions was between 323 and 325 , 325 and 328 where there was clearly something was with a purpose. the purpose does not matter, but when you take a peek at their brains (ecus) there will be a clear difference, even on the same cc engines, and all the physical differences have their own complement on the software side.

you talk about welding exhaust ports have an effect over intake, yes indeed, when applied restriction, but have no effect when opening out, or applying flow. ....yes, because of valves they still close at the same time with the same little to no overlap when power develop the most. There can be gains by the time of overlap, but this occurs only by the middle of the power band and there is not enough aggressiveness in rpms to offer enough flow to translate into worth to mention power.

 

TMS dyno for the 323 with tune, intake, exhaust was 14hp gain at top end.
With headers and cams you can certainly expect more.

 

M52B25 with mentioned upgrades + M50 manifold as an addition will put around 220bhp and varies depending on how aggressive the cams are and by how much tuner will go into ecu changes. - to be more on topic

 

https://forum.e46fanatics.com/showthread.php?t=768715 as an idea, thread starter, take a look at those dyno numbers...and take a peek at Dyno type details when numbers are making you smile.

 

Put a set of heads or a intake on a flow bench and you will learn about airflow. I use to build NASCAR engines and you could open the ports and intake to much that it starts to loose air flow. In those situations we used a special epoxy made for that. We never did anything to the exhaust ports except clean them up. Removing any cast lines. Yes they run headers to straight pipes. But the engine dyno has a set of big truck mufflers. Can still be heard 1.5 miles away. 800hp at the crank at 8k rpm you feel the concrete floor shaking. It’s an awesome site.


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when you built those engines, do you use fuel for those 800hp ,or they could run on 7L/100km and a bunch of air ? After cleaning and opening all those paths, calculating all the roughing and polishing, enlarging valves and tripling that flow ,you just make power ? Somebody have an afr in mind or i am starting to go crazy ? Who t.f. make power from air ,cause i want to do myself ? i dont want to use fuel anymore,i just want air (water too , but i can wait)

 

The only and cheapest way to make power is forced induction. Or if you are feeling brave then throw nitrous on it. Wouldn’t recommend anything bigger than a 50 shot on a stock engine. But headers intake cams and a tune, you will be disappointed in the results and for the money you spent on bolt ons that don’t add very much bang for the buck you could have went forced induction or a bigger engine. I’m talking from experience. The cams will cost the most and the most expensive hp per dollar. A 2.3 is not a engine that’s ever gonna do anything without serious internal mods like bigger crank and bored out for bigger pistons and higher compression ratio.


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reported to hp gains by turbing the engine,yes, is the cheapest, fastest and easiest way if you do it by yourself. If you pay for the kit and for the job is the same as if you invest into another car. Most of the guys with small engines search for a cheaper way. And some of them belive things like 20whp from a bolt on without compensations or car brain surgery. Judging by others numbers ,they feels confidents with double digits gains from double digits dollars costs. when somebody tells me that i can gain 25 from headers 10 from filter, 15 from exhaust ,i am more pleased to pay 300$ for 50hp than 2~3k for 80 turbo

 

No way in the world you will gain 50 hp from those mods. And all the gains that the manufacturer gives are bogus. For example a couple of years ago we put a e46 M3 on the dyno to see what a intake would do. It gained 1hp. And on the box said 10-15 hp gain. Bs. Dyno your car now then afterwards you won’t make a extra 50 hp. Sorry I have built NASCAR engines and been at this 30 years. Only bolt on mod that gives those gains are forced induction or nitrous.


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No way in the world you will gain 50 hp from those mods. And all the gains that the manufacturer gives are bogus. For example a couple of years ago we put a e46 M3 on the dyno to see what a intake would do. It gained 1hp. And on the box said 10-15 hp gain. Bs. Dyno your car now then afterwards you won***8217;t make a extra 50 hp. Sorry I have built NASCAR engines and been at this 30 years. Only bolt on mod that gives those gains are forced induction or nitrous.


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not me are the one who must hear that..,. i`m the bad guy that hardly try to open up few more pair of eyes. A better quotations for most plug n play stuff are " it can sustain up to 'x' amount of power with proper adjustments"

 

I read a thread a while back about these guys in Europe put individual throttle bodies on a m54 3.0l. It lost 35 hp and 44 ft/lb of torque there’s such a thing as too much air flow you can have a big hole in a intake on a flow bench and then add material back and it will move more cfm.


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there is a point/diameter/lenght where air flows best ,any extra size will hurt power as same as any restriction will do. On smaller diameter runners,air go faster and can fill better a chamber than if the air pass through a bigger hole. N/A engine

 

Easiest way to get rid of rear lambda is reflash the dme with the Euro dme file because they didn’t use post cat sensors.


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Easiest way to get rid of rear lambda is reflash the dme with the Euro dme file because they didn***8217;t use post cat sensors.


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There are still 4 probes ,2 pre and 2 post on the euro M54/M52TUB , but pre `98 year M52/M50 use just 2.

 

I know you can do it to the e46 m3 I do it a lot.


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there can be made an adaptor plate for any M5x engines too, and quite easily hook up ITB cable even to new M54 electronic throttle motor removing the plate and screwing a small role. But without extensive tests and adjustments engine at most will keep what it has,or it will lose power. Torque will be lost anyway where it counts most in a daily.
EURO e46 M3 came with ITB only. they are pretty expensive for a part here ~400E