Turboing a 325, a few questions.

[MarkT]

Hi there, I have been looking buying a 325 sport ('87) and turbo charging it.

I would like to know what the CR of the engine is, and how strong are the internals. I'm led to believe that the 325TD manifold is a straight swap and will take a T3. What are the flow restrictions like? Will the rest of the TD exhaust system match up?

Many thanks

Mark

[chip-3door]

Having seen the manifold in question, i would say that you would reach the limit of what boost you can handle on the stock CR before you are likely to hit the flow limit of the manifold.

Its a very similar design to the vauxhall c20let manifold, but bigger and 2 extra cylinders, and that vauxhall one will flow 300bhp!

(im using the LET as an example as i think i recognise your name from MIGweb?)

[MarkT]

Cheers chip.. Are you the same one from MIG, RB and Passion Ford? :p

[Jhonno]

cr on an early sport (pre 88 is 9.0:1 iirc (or something v similar)

still good for turbo charging

[Jon_Bmw]

Hi there, I have been looking buying a 325 sport ('87) and turbo charging it.

I would like to know what the CR of the engine is, and how strong are the internals. I'm led to believe that the 325TD manifold is a straight swap and will take a T3. What are the flow restrictions like? Will the rest of the TD exhaust system match up?

Many thanks

Mark

Right then, pretty much no, no and no to be honest.lol

Firstly get a later facelift 325 as the CR is lower and to be honest I wouldn't do it on a sport seems a shame to kill one if you blow the engine up by overboosting it. The 325TD flange is not a straight swap, budget about 10 hours modifying it. It doesn't have a T3 flange. The t3 flange was only on the left hooking 324td as seen in other countres like the netherlands i believe(m21 engine i think)

I don't think the rest of the exhaust system will line up but don't know for sure. But i think you would be the luckiest man alive if it did as the turbo is mounted underneath the manifold on the M21 i think hence it won't.

I am currently doing a write up on turbocharging a car so watch this space.

Any more questions?

Jon

[Jhonno]

nothing wrong with the earlier sport engine to turbo.. its slightly higher compression than the later engine but its not exactly high

[chip-3door]

Hi there, I have been looking buying a 325 sport ('87) and turbo charging it.

I would like to know what the CR of the engine is, and how strong are the internals. I'm led to believe that the 325TD manifold is a straight swap and will take a T3. What are the flow restrictions like? Will the rest of the TD exhaust system match up?

Many thanks

Mark

Right then, pretty much no, no and no to be honest.lol

Firstly get a later facelift 325 as the CR is lower and to be honest I wouldn't do it on a sport seems a shame to kill one if you blow the engine up by overboosting it. The 325TD flange is not a straight swap, budget about 10 hours modifying it. It doesn't have a T3 flange. The t3 flange was only on the left hooking 324td as seen in other countres like the netherlands i believe(m21 engine i think)

I don't think the rest of the exhaust system will line up but don't know for sure. But i think you would be the luckiest man alive if it did as the turbo is mounted underneath the manifold on the M21 i think hence it won't.

I am currently doing a write up on turbocharging a car so watch this space.

Any more questions?

Jon

9:1 CR is fine for a turbocharged engine, especially a low boost pressure one, and even more so an old one where the dynamic CR is lower now anywy due to lack of valve seal and ring seal!
Not to mention the timing is a couple of degrees safer anyway if you only ever run it on 97ron when its mapped for 95 to begin with.

He means the foreign manifold, with the t3/4 flange.
He means the exhaust downpipe off the donor car, not the 325i one

[Jon_Bmw]

9:1 CR is fine for a turbocharged engine, especially a low boost pressure one, and even more so an old one where the dynamic CR is lower now anywy due to lack of valve seal and ring seal!
Not to mention the timing is a couple of degrees safer anyway if you only ever run it on 97ron when its mapped for 95 to begin with.

Well if thats true you learn something everyday, as far as
I know its always best to start off with lower compression as its less likely to detonate, shit i should have wacked the compression ratio up to 14:1

I know what you are saying it will be fine for a low boost, the difference between the facelift and pre faceleft won't make bugger all difference really, its just I thought the Mark would want to know where he could help himself if only very slightly.

He means the foreign manifold, with the t3/4 flange.

I'm led to believe that the 325TD manifold is a straight swap and will take a T3.

Hence i was informing this wasn't the case

He means the exhaust downpipe off the donor car, not the 325i one

I don't think the rest of the exhaust system will line up but don't know for sure. But i think you would be the luckiest man alive if it did as the turbo is mounted underneath the manifold on the M21 i think hence it won't.

I was actually refering to the 325td/324td downpipe perhaps i didn't make that clear.sorry.

[chip-3door]

9:1 CR is fine for a turbocharged engine, especially a low boost pressure one, and even more so an old one where the dynamic CR is lower now anywy due to lack of valve seal and ring seal!
Not to mention the timing is a couple of degrees safer anyway if you only ever run it on 97ron when its mapped for 95 to begin with.

Well if thats true you learn something everyday, as far as
I know its always best to start off with lower compression as its less likely to detonate, shit i should have wacked the compression ratio up to 14:1

No, 14:1 would be far too high, unless you are planning to run it on diesel.

Lower CR is only useful for higher boost levels, if you are planning on running moderate boost all you will do with less CR is make LESS power.

Its all about the boost level, thats why a 500bhp cossie runs a low CR (massive boost) and a 500bhp skyline runs a high CR (moderate boost)

Its also very fuel dependant too, hence i mentioned 97 octane, if it were to be run on 95 then i suspect you would be right that even at half a bar of boost it may risk DET unless you set the AFR to about 11 on boost to use the extra fuel as a det surpressant.

[Jon_Bmw]

I was kidding about the 14:1, that would go boom boom very quick. You are right about the petrol, i always try and use 97 ron(ultimate) and i think it does help, probably allows you another psi before DET.


P.S how to i have it set on my profile to have attach sig automatically, keep forgetting, ANT?

[chip-3door]

I was kidding about the 14:1, that would go boom boom very quick. You are right about the petrol, i always try and use 97 ron(ultimate) and i think it does help, probably allows you another psi before DET.


P.S how to i have it set on my profile to have attach sig automatically, keep forgetting, ANT?

Just go into the profile bit and set it to yes mate.

[Jon_Bmw]

I was kidding about the 14:1, that would go boom boom very quick. You are right about the petrol, i always try and use 97 ron(ultimate) and i think it does help, probably allows you another psi before DET.


P.S how to i have it set on my profile to have attach sig automatically, keep forgetting, ANT?

Just go into the profile bit and set it to yes mate.

Thank you Mr custurd!

[chip-3door]

LOL
No worries mate

[Ant]

I can make a adaptor to use on the stock manifold Mark T, can be fitted with any flange although single entry T3 is the way forward.

Must say a boosted M20 is quite a weapon in the dry, plain lethal in the wet

[chip-3door]

Low pressure turbo isnt going to be very lairy.

Well not to those of us used to trying to put 350 odd bhp down through an 80s ford rear end anyway

Will be fine


How much do you charge for the adaptors, and do you hve any pictures?