due to financially trying times , i have had pass the ownership of my cab over to my old man . now its not quite as upsetting as it could be as he's got the money to spend on it and will get it finished .

 back on topic ,,  he wants to give it a bit more grunt once he/we sort the suspension out (horrible understeer oversteer type of feeling) . i wont be doing any major mechanical mods for him as he just wants a little bit more ooomph . it allready takes out stage 1 rs turbo's but it still feels slow to me

 i was just wondering who has modded their 2.5s and what sort of power output they have acheived ? i allready fitted scorpion stainless and filter . it has the 325 motorsport lump in it and im not sure if theres any difference at all from normall 2.5s?? 

tbh i got bored with it lacking in the power department so i look forward to trying to get it quicker with someone elses money .

opinions experiences welcome

taa muchly

I am the supplier of Viper2 chips PROVEN to give the best results on the 325i (as well as other models)

On the rolling road days the Viper2 always comes top.

07815-501867

I'd say that air filters and big bore TBs are only gonna increase top end power, if they do anything at all.

If your ol' man's got some cash, you'd most probably be better off getting someone who knows the engine to port and polish the head (by which I don't mean spend 5 mins with a flap wheel).

Then, a big restiction to the power of these and similar engines is the AFM, the removal of which means an ECU which is mapped on engine speed and load alone.

Next, look at decent tubular exhaust manifolds paying particular attention to what each one will give you, 6-3-1 manifolds yield different results to 6-2-1's.

If you can wait untill April next year, I'll be experimenting with a properly gas flowed head, and Emerald ECU and direct to head throttle bodies to see what improvements they bring.

There is no cheap way to bring about a decent gain. 7 or 8 bhp is worth practically nothing in real terms, especially if it moves power up the rev range. You'd be better off making the car lighter if anything. Around 100kg in weight loss is roughly equivelant to gaining 80bhp in terms of acceleration!

Actually, I guess that last bit is cheap :)

Ye pays yer money.......

Hmmm, now for the proper answer.

The ported throttle body will give you far greater pulling power throughout the rev range and it is noticable.

The chip is also VERY noticable, (ask forum mod nigel, i did his)

Porting the head is worth 2-4hp (if you manage to make power)

I had a 3 grand head on my car and trust me, there are little gains in the head porting, in 1991 CCC gave an M20 head to Dave Vizzard and in 2 weeks of extensive work he got 2hp !!!

The m20 and m30 heads are very good standard.

Now for the afm.

Yes, get rid of this and fit a map and you will be happy, this needs aftermarket ecu like emerald, vtech, etc etc.

Throttle boddies like dbillas are good but cost 1800 quid and will make many problems setting them up.

Get throttle body, chip and decent air filter and you wont regret it. 

thanx fella's

 as i said im not going to start  porting and polishing , altering compresion or changing any major mechanical items . tbh  big power gains arent possible without spending loads on any motor . but a couple more ponies or lb ft are allways nice .

what about a cam ?   i fitted a schrick item in the 5 and it did the job but that was a 3.5 !

injectors ? higher cc capable injectors   with a re mapped ucu to match ????

obviously a decent zaust fanimould and free flow system will help it breath  but untill you get to high modification levels i cant see the benefit .

what throttle body do you suggest jason ? is it worth removing the  air flow meter ? if so is it actually possible to make the ecu run it properly without one ?

what sort of power hikes are we looking at with

higher flow rate injectors, throttle body , cam ,and the filter and zaust i allready have ? someone must have done something similar allready !

I'd use a Schrick cam, the increased size throttle body, have a MAF fitted instead of the AFM then you'll have to use stand alone management to run the fuelling, that last option won't be cheap but i've seen it in a car and felt it, sounds wicked to!

Best to have it mapped on a rolling road by a reputable firm if you're after then best gains, if you want to move the power band up the rev range then fit an aftermarket exhaust.

allerady has a single box , 3" stainless scorpion .

 i did wonder how the ecu would run it with out the afm

chippeduk wrote: Hmmm, now for the proper answer. The ported throttle body will give you far greater pulling power throughout the rev range and it is noticable. Porting the head is worth 2-4hp (if you manage to make power) I had a 3 grand head The m20 and m30 heads are very good standard.

With respect, that thing about the TB is a load of cobblers. The engine wants to fill it's cylinders all the time that it's running. The throttle attenuates the flow so that they only partially fill and the engine doesn't rev it's big-ends off all the time.

Now, make the TB slightly better at flowing gas and all you'll get it slightly better power for a given throttle opening, but the power at a given engine speed it likely to be exactly the same as it ever was.

Only when the TB becomes a restriction in it's own right, at wide open throttle, will you notice a gain.

Also, the TB is bolted to a sand cast aluminium inlet manifold which is rough as a bears behind and doesn't exactly aid gas flow.

I'll admit that different heads respond in different ways to porting. However, if you paid £3k, then you were stiched up like a kipper! For around £700 you can get a reputable company to port a 16v head to race spec (none of this stage 1,2 and 3 <rap) so a 12v shouldn't be any more expensive.

Again though, the specific power output of these engines isn't anything to write home about and that's because they were mass produced with no particular attention being paid to the finish of the relevant bits.

hehehehe.

I know all about race engines and builds.

The FACT is there are not worth the high costs when modding the M20 head.

If dave walker could only get 2hp from this head by porting and flowing then you tell me someone who can get much more.

Of course this does not relate to all engines, My escort cossie saw 14hp from head work (not cams) so i know how they work but this thread was about the m20 head.

Anyway, back to the throttle body.

You will definately see a gain throughout with the ported throttle body.

Having said that, the gains felt when driving are more spectacular.

I am yet to find someone who has done this and said they didnt notice the difference, if you know of anyone please point them here to explain. 

P.S) my head was kinda highly modded with regards valves, ports, gear etc etc.

Mind you, i`m probably a joker who is making a wild guess at all these claims :D

chippeduk wrote: Mind you, i`m probably a joker who is making a wild guess at all these claims :D

Well we didn't want to say anything

Only kidding, but you're right about that level of modding, just not worth it on the M20 IMO, if i was at a stage where i needed polishing and head porting then it'd have to be on a multivalve engine to make it worth my while.

Or you could remove the m20 and fit this instead:

Trust me, its cheaper than modding the m20

nice !!

evo motor i presume ? 

tbh if performance was really the biggest issue with the car  we wouldnt have bought it , but we do feel its a little sluggish hence the post .

i think its probably gna end up with a cam and a chip as long as it keeps its driveability we,l be happy . if it was a real performance issue i,d be looking at doing a low comp turbo conversion or the twin supercharged jag v8 but it really isnt worth it .  i think i have spoilt myself by driving  really fast cars like my saff and now it allways feels like everything else is positivly slow . 

 as for high power e30's , one question ,,,,  what diff , g box would you use ? surely the e30 stuff wouldnt handle it too well ?

I am using a hartge dif and en e36 328i box.

As for your engine, i would do the following which is proven to transform the engine and the way the car drives.

Chip

Throtle body

Sealed air filter or better pannel filter.

I can try and help here.

I have a copy of an original alpina ecu code.

The C2 alpina (B3 in germany) was a 2.7 litre M20 powered car produced with 218bhp.

They released this car to the insurance people who give an estimate on insurance rating etc etc and they gave it a high grouping.

They then modded the car to give lower power and changed the mapping too produce 210hp.

I know this is not in relation to the throttle body but it shows of why manufacturers mod cars backwards to aid the selling process.

The e30 325i M20 was actually 191hp but was sold as 170hp after being throttled.

The e36 325i M50 was actually 204hp but was sold as 192hp after being throttled.

typical germans ,,,  take a standard car spend thousands on research and development  put a bigger engine in it to get more power  then de tune it to make it slower .........  actually not like the germans at all ???  

i didnty realize the 2.7 conversions released that much bhp , i shoulda just repaired my old one

I also have yet to see any theory to back up the ported TB claim. If someone could explain to me why it should work, after I've explained why it shouldn't, I'd be much happier about the whole thing.

Also, what do you do to a TB that costs £120?

You can't remove any metal, or the butterfly wouldn't fit so other than getting some polish and rubbing that around the inside, which anyone could do, what's the process?

That probably all sounds a bit harsh, but if your theorys are sound, then there shouldn't be a problem posting them :)

in this case i dont think you fully understand the work of alpina527

the unit is ported quite extensivelly and i think he fits a new butterfly to fit the larger diameter.

chippeduk wrote: in this case i dont think you fully understand the work of alpina527 the unit is ported quite extensivelly and i think he fits a new butterfly to fit the larger diameter.

.....and there are lots of people willing to vouch for the power increases that his throttle body yeilds.

a piccy to view whats done.

Ooh very nice :)

However, fact of the matter is that untill the TB becomes a restirction in it's own right, i.e. at WOT, you won't see any power increase.

You will however get more power for the same throttle opening, but that's not to be confused with having more power at a given engine speed.

Power isn't made miles away from the engine in the TB. It's made in the cylinder head and is more influenced by the tuned length of the induction system and the shape of the ports than the TB attached to it. However, everyone seems to think that big is best.

Unfortunately, if you did want to fit high lift/overlap cams, you'd probably find it necessary to ditch the plenum intake for individual TBs anyway as you'd find the car a real pig do drive around town without doing so.

Still, each unto their own.

Ahh, its all in the wording.

Of course, this wont give you much top end power but when are people really after this on a road car ?

what it does do is open the power band making more power throughout the rev range.

No, that's all it'll give you.

The TB's not a restriction untill the engine's going quickly, so a bigger TB will only increase the top end.

thats wrong.

how come a ported head gives a wider power band ?

GT6-M3 wrote: Ooh very nice :) However, fact of the matter is that untill the TB becomes a restirction in it's own right, i.e. at WOT, you won't see any power increase.

The throttle body is used to restrict the power on many engines. The Ford zetec engine for example and the old 16v 150bhp Vauxhall engine. Any engine which sees gains just from fitting individual throttle bodies must have some sort of restricition in the standard throttle body. Alpina527 sells them for the 6cyl 328 and 323 engines (and others) which are restricted by the manifold/throttle body.

its the case on nearly all bmw models of the recent era.

i know for a fact that the m20 and the m50 were hindered directly by the throttle body (and/or) inlet manifold, to lower insurance grouping.

Why doesn't someone try one and see what difference it makes?

That way we would no conclusively either way!

i have done.

fitted one on my own car and it made 6hp (although a little of this can be down to different heat temps etc etc)

they have been fitted to dozens of bmws, you only have to look on http://www.e36coupe.co.uk - www.e36coupe.co.uk forums to see whats thought of them

chippeduk wrote: i have done. fitted one on my own car and it made 6hp (although a little of this can be down to different heat temps etc etc) they have been fitted to dozens of bmws, you only have to look on http://www.e36coupe.co.uk - www.e36coupe.co.uk forums to see whats thought of them

Do you have dyno results to show the increase

If you do you could scan them in and let everyone see. 

I know that the modified throttle body that Alpina527 does for the 323/328 is very well thought of. If my bonus is as good as I hope I will be getting one along with the manifold early next year

Here you go! Before and after

http://www.e30zone.co.uk/tbfaq.asp - http://www.e30zone.co.uk/tbfaq.asp

Fair enough, hat eating time!

Exactly how much difference does 6bhp make though?