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Discussion Starter · #1 ·
i currently own a alfa romeo 75 1986 2.5l v6.

The engine is running well and in good cond.

The car currently has a performance exhaust system, extracters, racing suspension and 17" rims with low profile tires. It runs very well and handles exellently, but i am looking to further increase the performance of the car without doing anything drastic or expensive. My father is a mechnic so i can do most upgrades at home i just want to know what more can be done to further increase the performance of this car.

Thankyou
 

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What's your deffinition of drastic modifications?

Making sure the basics are in top condition would get the best out of what you already have L-jetronic Fuel Injection Technical Troubleshooting Article.

Maybe a larger BMW airflow meter but only if you have measured any flow restriction caused by the standard 1. No point otherwise.

Without making real changes, you aren't really going to get any real impovements.

A decent programable engine management system would allow you to get rid of the airflow meter and tune fuel and ignition to best suit your engine and local fuel.

Port the heads Scott Potter's V6 Porting Article.

Getting higher compression in there would be a good help.

Different cams.

A 3 litre.

Greg Gordons supercharger kit Supercharger Kit.
 

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Discussion Starter · #5 ·
What's your deffinition of drastic modifications?

Making sure the basics are in top condition would get the best out of what you already have L-jetronic Fuel Injection Technical Troubleshooting Article.

Maybe a larger BMW airflow meter but only if you have measured any flow restriction caused by the standard 1. No point otherwise.

Without making real changes, you aren't really going to get any real impovements.

A decent programable engine management system would allow you to get rid of the airflow meter and tune fuel and ignition to best suit your engine and local fuel.


Port the heads Scott Potter's V6 Porting Article.

Getting higher compression in there would be a good help.

Different cams.

A 3 litre.

Greg Gordons supercharger kit Supercharger Kit.
do you know how much porting the heads will cost. and where do you think it would be best to get a bmw airflow meter? And do you have any idea how much a decent programable engine management system would cost and where i could get one i am just trying to work out what would be the most cost effective and get good results thx heaps for the trouble..
 

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You should put your location in your signature.

The idea of posting that link for the head porting was to encourage you to do it yourselves.
 

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Discussion Starter · #7 ·
You should put your location in your signature.

The idea of posting that link for the head porting was to encourage you to do it yourselves.
My location is blue mountains NSW.

Yeah when i looked at that article you showed me, i realised it was to do it yourself.. do you know what percentage the exhaust flow is compared to intake flow of a stock 75. How much should i port it.. how many mil.
Is there anything that can go wrong with porting the heads such as loss of crompression.. i am very new to engines. thx
 

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If you're new to engines I'd avoid porting the head. It's pretty much a black art and you can end up with less power than you started with!

Joking aside, the reason I suggested a 3 litre engine is that you're starting with 188 bhp which is about 30 more than a stock 2.5 litre. It would cost a surprising amount of money to find that 30 bhp from a 2.5 so you're better off switching engines. Even the 24v 2.5 in the 156 only came out at 190 bhp which gives you an idea of how much head work you'd need to equal the 3 litre figures.

If you're really lucky you may find someone who needs a 2.5 V6 and you'll get most of your money back by selling them your old motor. Keep an eye out for written off cars of scruffbags that are being given away. The 7x15 Revolution wheels on my Twinspark came from a FREE 3 litre V6 75 that was being scrapped after it failed its safety test with terminal rot. This was 6 years ago and I sold the engine then sorry!
 

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Discussion Starter · #9 ·
new engine - NSW

yeah that sounds like a plan one of my friends iis doing exactly that now.. he just bought a 3.0 from a newer 156 and has only needed to make a couple of modification to fit the engine in.. where would be a good place to look out for old car, engines or front cuts?
 

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Commodore V6?
No, maybe not.
Though they are plenty cheap and powerful.

Just cleaning up the ports will help, a bit. But not enough to warrant pulling the heads off just to do it.

Update the ECU to a newer aftermarket unit that you can tune yourself.
May be be good for an extra 5 to 10 HP or 5 to 10 less if you don't tune it right.
And will cost you over a grand whatever system you use, even megasquirt.

A 4.1 rear axle

My 2.5 goes like stink with just those mods, but it is only pulling 900kg.

If you do the 3.0 swap let me know if you want to part with the 2.5.
 

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Discussion Starter · #12 ·
airflow meter...

I want to find out if the stock airflow meter is restricting the air flow but i dont know how.. And if it is what BMW should i steal a airflow meter from? because buying a programable engine management system would cost lots.
 

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I want to find out if the stock airflow meter is restricting the air flow but i dont know how.. And if it is what BMW should i steal a airflow meter from? because buying a programable engine management system would cost lots.
Here are a heap of articles on how to mesure pressure drop after things like airflow meters. Read Stuff On Here

As for what BMW, I believe it was the 535 (3.5(ish) litre 5 series) from the 80's that is the 1 you're after.
 

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Commodore V6?
Tar and feathers?

If you do the 3.0 swap let me know if you want to part with the 2.5.
There you go, sold the old engine already!

I think there may be a lot of work involved in adapting a 156 engine to go in a 75. We've got a 164 Twinspark engine here that we're looking at as a conversion for 105 series cars (75 Twinsparks are getting harder to source). This 164 version is significantly different and it looks rather like we'll just end up using the crank and head as there's so much that would need to be swapped over to make it fit a RWD chassis that we'll throw most of the rest away!

Not saying it can't be done, just that it'll be a fiddle.
 

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look at my VEMS install. I also put in a 164 motor at the same time. as I went from 3L to 3L I used my old crank flywheel and front pulley. as I wanted to keep it balanced.

But if I did it over I would use the 164 front pulley and just change the pulleys on the other parts to use the new type of belt.

as for the flywheel. the 2.5 will fit with a spacer. but it will need to be rebalanced.
I would just take the 3L FWD flywheel to the balance shop and have them make the 2.5 one match the 3L one.
you could put on all the 2.5 stuff. intake etc. but I would say take the time and cost to use the 164 intake and a programmable ECU or the 164 ECU.
if you get one of the newer 'S' if you can with the oil squirters I would say you need to use after market ECU. as you can not fit a dizzy as the motors with the oil squirters run the oil pump faster to make up for the demand of the oil squirters. fitting a dizzy on the pump will spin at the wrong speed and not work. but a after market ECU you run EDIS
no mater what you do it is going to cost some cash. but no more the a lot spend on silly large rims with a rubber band of a tire
 

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Sorry to be so sincere, but for all I have read from you (Alfa75rob) here, it seems your skills or knowledge about engines are limited, so forget aftermarket ECU, porting... etc. etc. I recommend you as much swap your engine for a 3.0,

Sorry again.
 

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Hello,

What do you mean? Do you mean you cannot even move the car until the water temperature is 80C? It's not good to let the car idle until the engine is warmed up. You need to put load on the engine, although not excessively when it is not warmed up. This means, you should neither let it sit idling nor should you rev it to 7000rpm.
 
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