What are the best engine mods to increase power in E30 325i

[Rosc0PColtrane]

Go for the M50!!

much better to build an m20 2.7 with a whole life ahead of itself rather than have an engine that when at its best made 192hp and 181lb-ft which was probablty 100,000 miles ago.

That arguement cuts both ways. The base lump could also be subject to the same bower drops and why spend lots of cash to get IRO 190- 210(ish) HP out of a 2.7

At least with the m50 you're getting a out of the box solution and have a higher horsepower base to work from. IE M20 was 172 bhp stock. M50 192 HP from stock. AFAIK, the M50 will return better fuel economy figures too.

A proper 2.7 build is a task to be undertaken by a skilled engineer with a matching bank balance. A lower spec build will net the same figures as m50 stock.

[ed325i]

Bmw chose a tame cam profile to keep the power down so a cam change should be top of the list.
A 6 branch can lose you bottom end torque.

[reggid]

Go for the M50!!

much better to build an m20 2.7 with a whole life ahead of itself rather than have an engine that when at its best made 192hp and 181lb-ft which was probablty 100,000 miles ago.

That arguement cuts both ways. The base lump could also be subject to the same bower drops and why spend lots of cash to get IRO 190- 210(ish) HP out of a 2.7

At least with the m50 you're getting a out of the box solution and have a higher horsepower base to work from. IE M20 was 172 bhp stock. M50 192 HP from stock. AFAIK, the M50 will return better fuel economy figures too.

A proper 2.7 build is a task to be undertaken by a skilled engineer with a matching bank balance. A lower spec build will net the same figures as m50 stock.

Its debatable which costs more a built 2.7 or m50 swap but consider one engine will be rebuilt and have 100k atleast before needing any further rebuild and the other has already done 100k and llikely not running at its best anyway. Consider life cost not initial outlay and there is no reason whay a 2.7 can't be as economical its all in the tuning.

No doubt a m50 makes more power out of the box than a m20 2.5 but its figures are not impressive and hardly worth the effort, i just don't see the logic behind swapping a 2.5 for a 2.5, the M52 on the other hand is a good swap because it has more than 10% torque advantage over an M50 and is seriosuly resticted from the factory so its cheap to get another 20-30hp and have a good allround engine torquey and powerful but with an m50 you get neither really. These are just my opinions.

[reggid]

Bmw chose a tame cam profile to keep the power down so a cam change should be top of the list.
A 6 branch can lose you bottom end torque.

any cam on a 2.5 that gives a good boost to hp will lose bottom end aswell. On a single cam, 2V per cylinder small engine these are the tradeoffs that must be made

[Rosc0PColtrane]

I think ant has built 2.7's at a cost of £4k?

[maxfield]

But that is certainly worth it.

You know it isn't being done by a monkey.

You know he is an enthusiast.

You know the engine will perform.

[ed325i]

Bmw chose a tame cam profile to keep the power down so a cam change should be top of the list.
A 6 branch can lose you bottom end torque.

any cam on a 2.5 that gives a good boost to hp will lose bottom end aswell. On a single cam, 2V per cylinder small engine these are the tradeoffs that must be made

With a 270 or 272 degree cam the car with remain driveable with lots of torque and you should get 10 -12 bhp.
On my 2.8 I will fit 2mm bigger inlet valves if I can find some and 1mm bigger exhaust valves.

[Rosc0PColtrane]

But that is certainly worth it.

You know it isn't being done by a monkey.

You know he is an enthusiast.

You know the engine will perform.

No doubting that, was just using the build cost comparitively with the cost of an m50 build

[reggid]

bollocks, if you believe for 1 minute there is an exhaust manifold which will give 18bhp then your dreaming big time. If this was the case don't you think there would of been another manifold developed long before this?
The fact the btb2 is based heavily on the hartge, Racing dynamics manifolds say alot, don't you think?

Don't believe everything you read.

I've fitted and driven before and after a 325i with a btb 2 it made a difference but not 18bhp, maybe 5 brake. I also have just rebuilt the top end on my 325i and added a cam to it. A noticible increase in power.

If you want your 325i to fly then put it on a major diet, this will only cost you your time and creature comforts such as carpets and door cards

If you want to tune a 2.5 start with a cam and go from there, but it's gonna need remapping and £Â£Ã‚£ to get a solid 190bhp. The cam is the weak link in the engine and is seriously mild. The standard log manifold is alot more efficient than you may think.

given that i almost doubled the 18hp claims made for a stock 325i on my big stroker and i am talking independant dyno verification here not some ass dyno, so i have no reason to doubt the claims of ~18hp from a stock early m20b25. You don't have quantative data to back up any of your comments as you have not done any dyno testing of BTB manifold or your cam job. There is serious night and day difference between the BTB and cast job from 3500 rpm and up there is simply no question about this.

I do agree about the weight reduction as this takes place at all rpms not just the topend

[ed325i]

I think ant has built 2.7's at a cost of £4k?

How can you spend that much on a m20 ?
I would find it hard to spend £4k

[ed325i]

bollocks, if you believe for 1 minute there is an exhaust manifold which will give 18bhp then your dreaming big time. If this was the case don't you think there would of been another manifold developed long before this?
The fact the btb2 is based heavily on the hartge, Racing dynamics manifolds say alot, don't you think?

Don't believe everything you read.

Read this >> http://www.e30zone.net/modules.php?name ... hlight=btb

[maxfield]

My dads engine was 12k to build, map etc so not impossible.

Big end bearings?
Main end bearings?
Piston rings?
Crank?
Rods?
Pistons?
Cam?
Valves?
Labour?

It all adds up.

[orangecurry]

bollocks, if you believe for 1 minute there is an exhaust manifold which will give 18bhp then your dreaming big time. If this was the case don't you think there would of been another manifold developed long before this?
The fact the btb2 is based heavily on the hartge, Racing dynamics manifolds say alot, don't you think?

Don't believe everything you read.

The standard log manifold is alot more efficient than you may think.

so what is in the Alpina C2.5 (which produces 190+BHP?) - tubular manifold and?

[reggid]

Bmw chose a tame cam profile to keep the power down so a cam change should be top of the list.
A 6 branch can lose you bottom end torque.

any cam on a 2.5 that gives a good boost to hp will lose bottom end aswell. On a single cam, 2V per cylinder small engine these are the tradeoffs that must be made

With a 270 or 272 degree cam the car with remain driveable with lots of torque and you should get 10 -12 bhp.
On my 2.8 I will fit 2mm bigger inlet valves if I can find some and 1mm bigger exhaust valves.

the car will be drivable yes, but have more torque down low with the stock cam because it will have more dynamic compression at low speed and you might get a 10-12hp on a engine with good compression but that is still lower than what a BTB gives. So when you start going bigger cams to get more power then the torque loss beomes very notieable.
The claim was made that a cam will produce double the gains from a BTB but in reality you'd struggle to get an extra 30+ hp from a cam change alone even with head work.

[ed325i]

My dads engine was 12k to build, map etc so not impossible.

Big end bearings?
Main end bearings?
Piston rings?
Crank?
Rods?
Pistons?
Cam?
Valves?
Labour?

It all adds up.

Most of that must of been labour.
I am going to start build engines for people.

[Rosc0PColtrane]

I think ant has built 2.7's at a cost of £4k?

How can you spend that much on a m20 ?
I would find it hard to spend £4k

It was a figure I seem to remember being banded about, forgive me if it was wrong.

[Rosc0PColtrane]

My dads engine was 12k to build, map etc so not impossible.

Big end bearings?
Main end bearings?
Piston rings?
Crank?
Rods?
Pistons?
Cam?
Valves?
Labour?

It all adds up.

Most of that must of been labour.
I am going to start build engines for people.

You should do mate, you know your stuff!!

[Simon13]

so what is in the Alpina C2.5 (which produces 190+BHP?) - tubular manifold and?

with the full fat 50mm bore alpina system a tame cam at 268/268 and ECU 190 no messing!

a tuned engine will benefit more from mods like a cam and 6 branch as the name of the game is getting air in and out as quickly as poss.

I have dyno plots on my cammed 325i it did 175bhp as it is but badly needs remapping on WOT to get the most out of it as it's running to rich top end and lean bottom end. What it makes ultimately who knows yet. the only other mods is a Racing Dynamics 6 branch. It hasn't lost loads of low grunt because a M20 2.5 doesn't have alot to start with. not bad for a bottom end with 222,000 miles on it. I've 1 more mod to do on the air intake and then i shall leave it.

How all your talk of 3.1 or 2.9 strokers and dyno plot this and that is relevent to making a M20 2.5 tick is beyond me.

I never stated that a cam will give double the gains of the btb2. If your that bothered............find a stock 2.5 RR it. fit a btb RR it. Then fit a cam and RR it. A cam is what makes an M20 2.5 tick not a 6 branch

[e30kev]

I Know the car isn' t going to be a drag racer but a damn type R integra pulled away from me on acceleration the other nite. It would be nice to know it could beat those girls cars anyway. I know they are quick 1.8 engines n all but still. I looked at a R32 Skyline with over 300 BHP the same day I bought the 325i. I don' t regret buying the bimmer tho i think I may try to obtain somethin jap turbo also if i can hopefully.

i wouldnt expect to go beating integra type r's, they all produce about 197bhp 1.8 and 2.0 versions and as there is a huge aftermarket tuning scene for them a lot of them especially the older ones are tweaked and you might just end up getting embarrassed unless you've invested some serious cash.

[DaveD]

Big Bore Throttle body
Magnex 6 branch
Scorpion BBox
piper induction
remap
=190bhp 187lb
since then
miller maf
hi flo cat and new centre section

lots of grunt low down not just at the top end

[Ant]

Oz engine was way under the 4K figure guys, inc all the machining and fitting etc, inc the remapped chip

Bargain I say.

DIY stroker is £1500 territory, mor eif you add new clutch,cam, and dont kid yourself on the total spent...

I offer these starting from 2K fitted, dependant on spec, and how good the exchange unit is.... ( fubar normally)

@ DaveD, sorry dude, I still struggle with the dyno figs for yours, they're approx 6% higher than I'd expect given the mods, but hey, you might have a got a "good one"

[DaveD]

O

@ DaveD, sorry dude, I still struggle with the dyno figs for yours, they're approx 6% higher than I'd expect given the mods, but hey, you might have a got a "good one"

what can't speak can't lie...got the pics (and so has oz and mat)

[Ant]

I'm not accusing anyone of anything Dave, as I said, you may have a "good one" it happens

oh, and FFSK can we stop comparing an M50 swop to a 2.7/2.8 build in terms of cost.

most M50s are on the wrong side of 150K, and would arguably benifit from a freshen up( and some cams ) but in 99.9% of reported swops, most have bought- cleaned- fitted the M50

now, strip, inspect and rebuild, then swop, the M50 will eat more £Â£ than an M20 simple as.

The strokers do still have a role to play here

[M5pilot]

Not many people have much experience of actually modding a car and then going straight to the dyno with it. Myself and Ant have done this many times now and on most occassions havent bothered to even post up the results due to too the discussions and accusations that follow from the so many experts on this forum.

Below are dyno results - done at reputable places. Before anyone suggests that these could easily be fabricated - it is not in the interest of the dyno operator or the person testing the car as anyone can take their car elsewhere. Oz's car is a great example, dynoed @ 220bhp at Bexleys and then 225bhp on another excellent Dastek machine.

Nadeem Hejazi's 325i sport with Schrick 284/272 Cam (fitted by Ant), BTB1 and a remap gave this: (180 bhp before and 189 bhp after and a difference of 10 lb.ft)


The above is a before and after, before is with a standard 325i chip and after a remap with a MAF conversion. The engine was tired to start with to say the least! The car was afterwards fitted with a BTB2 - the result was a car which was as quick as my M3 which put down 215 bhp on the same dyno. It plastered standard 325i's. The downside was a flat power delivery under 3000 rpm.

The BTB2 manifold on a standard 325i before and after gave this:



The people who did this dyno are a serious company as are BTB. If you want us to do this test again on another proper car then we are more than happy to do it.

Oz's car has put down 220-225 bhp on the same dyno with a properly built 2.7 and all the best bolt on mods - 220bhp on that dyno is impressive when most 325i's hardly manage 165 bhp.

The BTB2 manifold is neither based on the racing dynamics nor the Hartge. The primaries on the BTB are totally different in length and bore to both. There is an X pipe.

Basically, you can modify a 325i with a manifold, cam and a remap to give a far more lively car. Good manifolds will give a PROVEN 10+ bhp in isolation and a cam will give about the same. If the car is properly remapped then you can expect even more. I know for a fact that 195 bhp is quite easily possible from a 325i.

Not being big headed here but you guys can talk all you want but we (includes Bexley Motorworks,Ant and others) have done these mods practically and have shown that these mods work and give good dyno gains. Leaving the dyno aside the cars are also measurably quicker than standard cars.

Evo-S

[M5pilot]

Big Bore Throttle body
Magnex 6 branch
Scorpion BBox
piper induction
remap
=190bhp 187lb
since then
miller maf
hi flo cat and new centre section

lots of grunt low down not just at the top end

Dave, it is frustrating when people suggest that your dyno run may be a little optimistic. However, I think what Ant is suggesting is that the dyno you used may read slightly higher than the other dyno we use quite alot. My own totally standard 325i was dynoed there and gave 175 bhp, to get 15 bhp from the mods you have carried out is totally beliveable.

All dyno's read slightly differently, it's the comparison of one car against another on the same dyno that matters. Regaurdless of the figure, your car definatley gives +15 over a good standard engine.

Evo-S

[keet81]

Big Bore Throttle body
Magnex 6 branch
Scorpion BBox
piper induction
remap
=190bhp 187lb
since then
miller maf
hi flo cat and new centre section

lots of grunt low down not just at the top end

Cheers mate. How much you reckon for the lot incl. a remap and labour? I will be leaving off FSE I think.

[keet81]

Big Bore Throttle body
Magnex 6 branch
Scorpion BBox
piper induction
remap
=190bhp 187lb
since then
miller maf
hi flo cat and new centre section

lots of grunt low down not just at the top end

Cheers mate, plain and simple. How much you reckon for the lot incl. a remap and labour? I will be leaving off FSE I think.

[keet81]

Big Bore Throttle body
Magnex 6 branch
Scorpion BBox
piper induction
remap
=190bhp 187lb
since then
miller maf
hi flo cat and new centre section

lots of grunt low down not just at the top end

What' s miller maf?

[datonyb]

still think ya better off spending money on brakes and suspension first

power as they say is nothing without control

had many many 200bhp cars.it aint worth jack unless you can put it down to the road

my 2pence worth ..ker chink

[Jhonno]

if he has decent tyres, brakes are ok with uprated pads on an e30..

decents chassis is essential tho! best way to make a car more fun and 'better' start from the bottom up..

an e30 with 190bhp and a decent chassis would be a hoot to drive!! Hell my 316i auto, always put a smile on my face and that was a standard engine with quality chassis/brake setup

[reggid]

How all your talk of 3.1 or 2.9 strokers and dyno plot this and that is relevent to making a M20 2.5 tick is beyond me.

You said it yourself

the name of the game is getting air in and out as quickly as poss.

and knowing that the flow comes from the induction, top end and exhaust, it makes sense that since i use the same head casting, intake manifold, AFM, Air box, catalytic converter etc the relative characteristics will be somewhat similar.

I never stated that a cam will give double the gains of the btb2. If your that bothered............find a stock 2.5 RR it. fit a btb RR it. Then fit a cam and RR it. A cam is what makes an M20 2.5 tick not a 6 branch

You implied it since there aren't many £700 manifolds around.

Ed i mean all the air filters and 6 branches all cost alot, then you have a cam for say £250 and it gives twice the gains a £700 6 branch does.

[reggid]

Not many people have much experience of actually modding a car and then going straight to the dyno with it. Myself and Ant have done this many times now and on most occassions havent bothered to even post up the results due to too the discussions and accusations that follow from the so many experts on this forum.

Below are dyno results - done at reputable places. Before anyone suggests that these could easily be fabricated - it is not in the interest of the dyno operator or the person testing the car as anyone can take their car elsewhere. Oz's car is a great example, dynoed @ 220bhp at Bexleys and then 225bhp on another excellent Dastek machine.

Nadeem Hejazi's 325i sport with Schrick 284/272 Cam (fitted by Ant), BTB1 and a remap gave this: (180 bhp before and 189 bhp after and a difference of 10 lb.ft)

The above is a before and after, before is with a standard 325i chip and after a remap with a MAF conversion. The engine was tired to start with to say the least! The car was afterwards fitted with a BTB2 - the result was a car which was as quick as my M3 which put down 215 bhp on the same dyno. It plastered standard 325i's. The downside was a flat power delivery under 3000 rpm.

The BTB2 manifold on a standard 325i before and after gave this:

The people who did this dyno are a serious company as are BTB. If you want us to do this test again on another proper car then we are more than happy to do it.

Oz's car has put down 220-225 bhp on the same dyno with a properly built 2.7 and all the best bolt on mods - 220bhp on that dyno is impressive when most 325i's hardly manage 165 bhp.

The BTB2 manifold is neither based on the racing dynamics nor the Hartge. The primaries on the BTB are totally different in length and bore to both. There is an X pipe.

Basically, you can modify a 325i with a manifold, cam and a remap to give a far more lively car. Good manifolds will give a PROVEN 10+ bhp in isolation and a cam will give about the same. If the car is properly remapped then you can expect even more. I know for a fact that 195 bhp is quite easily possible from a 325i.

Not being big headed here but you guys can talk all you want but we (includes Bexley Motorworks,Ant and others) have done these mods practically and have shown that these mods work and give good dyno gains. Leaving the dyno aside the cars are also measurably quicker than standard cars.

Evo-S

If you have any results to post up even if there are pessimist around here who think its relistic/unrelatistic, good/bad or BS atleast its open for discussion and debate thats what the forums are for, it also gives people a better guide as to what can and can't be done as not everyone has access to people who know how to and actually have tune m20's.

I am not speaking about anyone in particular when i say that even things that haven't worked that well should be shared IMO not just all the good stuff because each car is slightly different in subtle ways and not all mods will do the same to each and every car.

When you say it "plasterd a standard 325i" and "measureably quicker" can you put it into context at all?

Cheers

[DaveD]

Big Bore Throttle body
Magnex 6 branch
Scorpion BBox
piper induction
remap
=190bhp 187lb
since then
miller maf
hi flo cat and new centre section

lots of grunt low down not just at the top end

Cheers mate, plain and simple. How much you reckon for the lot incl. a remap and labour? I will be leaving off FSE I think.

Magnex £300 s/h plus fitting
Scorpion £60 s/h plus fitting
piper £90
big bore throttle body (zone shop) £187 ( Forgot to mention this)
remap ---/new chip see zone shop

miller maf (do a search under miller)

[M5pilot]

reggid,

The 325i fitted with the mods vs the standard 325i.

From a standing start upto around 60mph the modded car pulls around 1-2 car lenghts infront after which the gap widens further as speed builds.

Both cars moving at around 50mph in 3rd gear - by 90mph the modded car has pulled a good 10 car lenghts and continues to pull away.

That's a significant difference.

As for posting information up - I agree everything should be posted whether it's good or bad. There are many users of this forum who just read and never post and rely on what we post to be the truth. Dyno graphs are the closest thing we have to actual proof of if something actually works or not.

We can clearly see that an M20B25 engine can give an extra 50bhp with a 2.7 conversion and the right parts used. There is no doubting this.

Evo-S

[Rosc0PColtrane]

reggid,

The 325i fitted with the mods vs the standard 325i.

From a standing start upto around 60mph the modded car pulls around 1-2 car lenghts infront after which the gap widens further as speed builds.

Both cars moving at around 50mph in 3rd gear - by 90mph the modded car has pulled a good 10 car lenghts and continues to pull away.

That's a significant difference.

As for posting information up - I agree everything should be posted whether it's good or bad. There are many users of this forum who just read and never post and rely on what we post to be the truth. Dyno graphs are the closest thing we have to actual proof of if something actually works or not.

We can clearly see that an M20B25 engine can give an extra 50bhp with a 2.7 conversion and the right parts used. There is no doubting this.

Evo-S

While a good visual demonstration. It would only be fair if both drivers drove each car exactly the same. Ie agreed rev levels to change gear at etc etc.

The best way would be for 1 driver to drive both cars, iliminating variances in driving styles