Low compression 1991 325i rolling road results! Good or bad?

[scot]

Hi people, does anyone know of a good garage with rolling road to power test my 325i?

It has a fair few miles under its belt (191k!) Although it did have a top end rebuild 5k ago and the compression is still good

I really want to know how much power its making

[DaveD]

there was this thread a while back but it seems to have gone dead now...might help

http://www.e30zone.net/modules.php?name ... light=#top

daz will know of any others ,,drop him a pm

[TVRTASMIN]

If it is just a power run you are after, then you could ask Well Lane Turbo Centre who are in Batley i think.

[scot]

Well lane turbo centre is looking good, just checked there website. I'll give them a bell tomorrow

Cheers guys

[scot]

Well Lane is £40 plus VAT for a power run. Have booked it in, will post results next week

[scot]

Right then here's the results!

First of all i'll tell you what i'm running.

Its a 1991 325i se coupe
Mongoose full stainless exhaust
Pipercross viper induction kit

159 bhp and 162 lbs of torque

Is this normal for a low compression engine?

[march109]

Think book is 170BHP

11 BHP loss for 16 years don't sound too bad, do you reguarly service her?

[dazleeds]

Right then here's the results!

First of all i'll tell you what i'm running.

Its a 1991 325i se coupe
Mongoose full stainless exhaust
Pipercross viper induction kit

159 bhp and 162 lbs of torque

Is this normal for a low compression engine?

not bad figures for the age

but i wonder would they have been better with an original air filter and box??
you may also find the exhausts holding back the power too

was this done at well lane??
im thinking of taking mine up there in a cpl months once the 2.7s in

[DaveD]

have a look at this thread
http://www.e30zone.net/modules.php?name ... lling+road

[spence_star]

Might help getting a straight pipe attached to your back box, and remove the cat should get more power

[shaggy]

Hello
Just for reference I've got a print out from my standard (bar a panel filter and drilled airbox) '89 325 130,000mls
164.5 bhp and 166.9 lbs
To be fair the air box cost me 2bhp!!!! But it sounds to nice to remove

[scot]

Yeah book figure is 171bhp but i've been led to believe tech2 engines have about 150bhp (ish) whereas tech1 has 170+bhp. Does anyone know if this is true??

Took the car to Well Lane in Batley to have the power run. Fella that did the run reckoned the Pipercross viper filters do give you a genuine increase in power (as per all the cars he's tested with them on)

Also i thought the mongoose exhaust did give more power than a standard system?

Anyway more to the point my engine has done 192k and as of this evening its back at the garage with another suspected cracked cylinder head
It was only replaced 3 months ago so still under warranty!

So that could explain the loss of power

[reggid]

Yeah book figure is 171bhp but i've been led to believe tech2 engines have about 150bhp (ish) whereas tech1 has 170+bhp. Does anyone know if this is true??

Took the car to Well Lane in Batley to have the power run. Fella that did the run reckoned the Pipercross viper filters do give you a genuine increase in power (as per all the cars he's tested with them on)

Also i thought the mongoose exhaust did give more power than a standard system?

Anyway more to the point my engine has done 192k and as of this evening its back at the garage with another suspected cracked cylinder head
It was only replaced 3 months ago so still under warranty!

So that could explain the loss of power

its a rolling road so unless you have a brand new 325i equipped with a m20b25 to compare to then the results by themself are meaningless. Also a low comp m20b25 makes more than 150hp

[PurpleMtec]

Mtec 1 are the best

[scot]

Sorry reggid you've lost me!

I take it you've got a tech 2 yourself?

ps. why are you up at this crazy hour?

[scot]

Mtec 2 look better

[reggid]

Sorry reggid you've lost me!

I take it you've got a tech 2 yourself?

ps. why are you up at this crazy hour?

First and foremost a dyno is a tuning tool and not one for determining accurate and realistic BHP numbers as a dyno number by itself us just a number (and each dyno reads differently) the number does not correlate directly to the "bhp" number that manufacturers claim (even despite power loss due to age/wear).

If you had a brand new low comp m20b25 (tech 2) you could compare your number to it (on the same machine) to see if yours has lost/gained power i.e. you need some sort of baseline/reference point to compare any dyno number to. You can also look at the numbers of other cars on the same dyno particulary newer cars to gauge what the power might be.

Around here whp (wheel hp) is used as correcting to BHP is non scientific for the more polite way of putting it. So as long as you use the same machine you can say whether a mod has gained power if you do a before and after otherwise all you are doing is paying for a number and a number that the operator may have massaged slightly to make you happy.

IMO BMW's claims of the same power between the low (tech 2) and high comp (tech 1) are not far off its the torque thats better on the high comp motor (it comes on earlier) and since you feel torque thats why they feel faster ( you can't really feel power) Power may be down slightly too. Also the O2 sensor can play a bit of havoc on the AFR in the low comp motors particurily after 15-20 years and if the idle and part throttle mixtures are a bit off.

Yes i have a tech 2 but the only tech 2 part is the block ,intake manifold and airbox which are likely the same/simialr beteen tech 2 and tech 1 everyting else has been upgraded.

I live on a different continent thats why i am up so late...

[scot]

Cheers for that Reggid

My car will be back on the same rollers as soon as its fixed (again!) So hopefully will see an increase.

Where are you based fella??

[reggid]

Cheers for that Reggid

My car will be back on the same rollers as soon as its fixed (again!) So hopefully will see an increase.

Where are you based fella??

Sydney, Oz

[scot]

Cheers for that Reggid

My car will be back on the same rollers as soon as its fixed (again!) So hopefully will see an increase.

Where are you based fella??

Sydney, Oz

Bloody hell thats a few miles from me

My cousin is in sydney at the moment with relatives, whats the weather like??

[scot]

So what is everyone else's 325i tech1 and tech2 cars making powerwise???

Its TECH 1 v TECH 2 come on place your bets

[jmc330i]

My touring was making 167bhp over a few power runs. I fitted the engine from my Sport (tech2) and its standard other than a drilled airbox and modded backbox.

[oakey]

when my tech1 was standard (apart from back box and k&n) it was just under 165hp after 140000 miles