S50B30 Turbo Engine Limits?

[BMEP 0]

Hi Guys,

Does anyone know what the maximum safe boost/power limit is if you were to turbocharge a E36 M3 S50B30 engine? My question is in reference to an approx 65,000-70,000Kms engine that has been well maintained. It goes without saying that i am referring to a detonation free/correct target A/F tune.

Thanks.

Edited July 12, 2009 by BMEP

[topcat 11]

before i give an answer, we will need some more info.

in essence, yes boosting is fine upto a point.<8psi as it is.

compression ratio?

changing the head gasket to a MLS?

boost level aspirations?

HP goal?

limited or limitless budget?

Head studs or factory bolts?

alots of combinations are possible of the info/Q's above.

folks love to lower the CR to 8-8.5 to boost upto 20psi.

personally, I'm not a fan of that as its possible to keep a higher CR with alittle less boost.

the results are really in the hands of the tuner.

[BMEP 0]

before i give an answer, we will need some more info.

in essence, yes boosting is fine upto a point.<8psi as it is.

compression ratio?

changing the head gasket to a MLS?

boost level aspirations?

HP goal?

limited or limitless budget?

Head studs or factory bolts?

alots of combinations are possible of the info/Q's above.

folks love to lower the CR to 8-8.5 to boost upto 20psi.

personally, I'm not a fan of that as its possible to keep a higher CR with alittle less boost.

the results are really in the hands of the tuner.

Thanks for the reply.

To answer your questions,

The engine is stock so the comp is 10.8 to 1.

Being the engine is stock the head gasket is also stock.

As for boost level...well that is my question. What is the highest boost anyone has run on a totally stock engine and what HP did they yeild at that given boost?

HP goal......, well at this stage there is not a goal, it will be dictated by the stock engines limits.

And finally it runs stock head bolts as mentioned it is a stock engine.

[Mark 178]

PM Matt (Ecko_complex) ... he's turboed his M3 on stock internals and will be able to give you insight/advice.

[topcat 11]

Thanks for the reply.

To answer your questions,

The engine is stock so the comp is 10.8 to 1.

Being the engine is stock the head gasket is also stock.

As for boost level...well that is my question. What is the highest boost anyone has run on a totally stock engine and what HP did they yeild at that given boost?

HP goal......, well at this stage there is not a goal, it will be dictated by the stock engines limits.

And finally it runs stock head bolts as mentioned it is a stock engine.

sorry,should maybe have asked- any planned up grades.

i would recommend not more then 6-8psi,simply cause the risk of the head gasket becoming oblong shape

[ecko_complex 4]

It's ALL in the tuning. I'm running 8psi (it can hit 9 when it's cold), and the tuners say I could put a little more through. It also depends how agressive your tune is. Anything beyond that and you're looking at internal work. A thicker headgasket has been well discouraged by many people, and changing the CR will pretty much ruin the engine (to me anyway).

[BMEP 0]

Thanks for the feed back/info guys. My M3 has covered approx 6,000kms since being boosted to 8psi with no problem what so ever. I was hoping to find a definitive answer to how much boost these engines (S50B30) can contain with a decent tune (No Det. correct A/F) before i decided to possibly elevate the boost to 10psi on the stock engine.

[ecko_complex 4]

Thanks for the feed back/info guys. My M3 has covered approx 6,000kms since being boosted to 8psi with no problem what so ever. I was hoping to find a definitive answer to how much boost these engines (S50B30) can contain with a decent tune (No Det. correct A/F) before i decided to possibly elevate the boost to 10psi on the stock engine.

Where are you? Pics are a must .

[BMEP 0]

Where are you? Pics are a must .

I'm in Australia. Happy to post pics as i have posted on other forums. Is it preferable to post pics here or perhaps start a new thread in the "Show Room" ?

[CamB 48]

Do the show room.

[BMEP 0]

Do the show room.

Done!

[mops 4]

you are pretty much limited by fuel.

can you affor 116 octane racign gas ? then most likely you will be ok up to 14 psi.

Basically with stock internals you will run into detonation very soon - maybe 8 maybe 10 psi... it depends on fuel quality greatly. running on 'on the edge' of detonation is not smart, one hot day, one bad batch of fuel, and you can melt the engine if you are not paying attention.

long story short, and i'm kinda oversimplifying here a liittle bit, however any engine will handle alot with proper tuning - key being avoiding detonation. detonation, even with no boost will melt the engine quickly. Hard to say exactly how long but generally Head gasket is like a safety 'deviece' which will blow first and hopefully you will realize it soon as it happens. If you are a smart a$$ and use metal hg clamped with fancy studs then HG will hold and either head will crack of piston will melt. and retarding ignition also has it's limits... any less than about 10 degrees might keep you from detonating, but you will be making actually less power than wil less boost/more timing - exact figure depends alot on the engine parameters.

there are several things you can do about it though.

-use high octane fulel, but realistically over certain detonation limit you will need more and more octane to keep from detonation

-use water/methanol injection - it also has it's limits.

-run dual fuel setup or some sort (kinda extension of abouve)

-keep intake temp and exhaust backpressure to minimum.

-probably there are more ways.

IMHO on NZ crap fuel you will be lucky with 8 psi, and that's provided you have fairly large turbo hot side. that includes full custom tune on standalone ems. maybe 10 on a good cold day with fantastic fuel. and then you go outside of main urban areas and best you can get is some 95 octane and that will detonate unless you reduce boost.

[BMEP 0]

Just an update for those interested in this topic, I’ve had been pushing 13psi boost threw the stock S50B30 on pump fuel for approx 3,500kms and the head gasket finally let go.

However I believe that the head gasket could have contained the Cyl pressure for a longer period of time (how long I don’t know) had the previous owner of the car regularly changed the coolant every two years as it was evident when i disassembled the engine that there was corrosion/rust of the head gaskets inner steel frame that would have aided in supporting the fire ring as can been seen in the pic……

The pistons ring lands looked fine with evidence of blow by past the top and second rings. When I removed the rings it was obvious that the rings had lost tension hence the blow by. I’d say that the rings had lost tension due to the steel/materials used in the OEM rings not being up to the task of handling the added cylinder temps in turbocharged form and loosing tension over time.

My disclaimer…Before anyone decided to rush out and push 13psi boost threw a stock S50B30 keep in mind that I have been Pro tuning for over 15 years. There is no doubt engine longevity is heavily influenced by the tune so don’t go trying to blame me if you hurt the engine. I’m mentioning this as I have seen people hurt engines at 5 psi boost due to poor tuning.

[E30-323ti 66]

So what is the recovery plan?

Just replace or improve?

[DrphTa 5]

Where abouts are you in Australia Jake?

Edited February 23, 2011 by DrphTa

[BMEP 0]

So what is the recovery plan?

Just replace or improve?

Improve...... Here is a little more info......

http://www.bimmersport.co.nz/forums/index....c=23958&hl=

DrphTa,

I'm in Sydney.