4-cylinder turbo performance

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Jim K
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4-cylinder turbo performance

Post by Jim K » Thu Sep 03, 2009 11:11 am

Since we seem to jump in and out of the 4-cylinder turbo scene, it seems only right not to pollute the 6-cyl threads with these incursions. I therefore propose to keep all such 4-cyl material in this thread if you all agree.

JkQV, if I had my way, I'd find a 1.8T and play with that. From what I see around here, the cheapest going recipe for this engine is the harness and ecu from the old Ford Sierra rwd, a nice intercooler and with 1.5-1.8bar you're looking at a safe 250-300hp -CR, cams and other parameters will have a big say in how high the final figure is! I don’t know where you are in the world, but they usually go for 700Euros and up, depending on condition of course.
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Re: 4-cylinder turbo performance

Post by kevin » Fri Sep 04, 2009 10:26 am

Jim , again my lack of knowledge on the 75 1.8t but what type prop does it have. ie is it like the GTV 6 or of the typical 2.0l alfetta type. With boosting this power are the guys using different clutches as well. You have to be a special kind of driver to race these(which is not me). ie keep the boost up before corner , chuck it sideways then aim for apex. This is what I heard from ex touring car drivers anyhow. last question is the charge cooler on the 1.8 t restrictive or is there just no space.
There are a few chaps in our racing series eyeing out these cars in Uk due to there perfect weight balance.
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Re: 4-cylinder turbo performance

Post by Giuliettaevo2 » Fri Sep 04, 2009 2:35 pm

the 75 1.8Tb uses a intercooler that is integrated in the intakemanifold. it uses a cardboard(?) tunnel to guide air from the front of the car through the intercooler. But since there is no way out after the air comes out of the intercooler it doesn't cool that good... :(

The Tb uses the bigger v6 type donuts in the front and rear, middle one is different if i remember correctly. Clutch is the same pull type as the v6 has. Gearbox has a nice finaldrive, 3.9. this is the same final drive a RZ/SZ has. Used this gearbox behind a 3.0 once, very pleasant car to drive, much improved throttle response and not to much revs on the highway at cruising speed.

Biggest drawback is the injectionsystem as Jim already explained...

@Jim;
Have also heard of the VW Digifant from the G60 being used on the Tb engine. The Ford system you mentioned is from the Cosworth i suppose?
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Re: 4-cylinder turbo performance

Post by kevin » Fri Sep 04, 2009 9:47 pm

Thanks for info.
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Re: 4-cylinder turbo performance

Post by Mats » Sat Sep 05, 2009 11:29 am

The duct was plastic, square hole next to the radiator and up against the intercooler. Pretty elaborate with turning vanes and all. Too bad the hood pretty much block the other side of the intercooler though. :roll:
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Re: 4-cylinder turbo performance

Post by Zamani » Sat Sep 05, 2009 7:39 pm

Mats,

Cutting some strips on the other side of the hood would help wouldn't it? Wonder why Alfa didn't think about that.
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Re: 4-cylinder turbo performance

Post by Mats » Sun Sep 06, 2009 1:00 am

Changes to the hood means new crash testing and validation, that's expensive. They didn't need that for GrpA. 8)
If they really wanted to do something that worked they should have put the intercooler up front.
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Re: 4-cylinder turbo performance

Post by Jim K » Mon Sep 07, 2009 12:38 am

Hi guys, I was away for 4 days and missed the action here.
Kevin, the 1.8T was never imported in UK either...if anyone wants used engines for these things, Germany, France, Italy and Greece are the biggest markets I think.
The driving tricks you mentioned were in fact used by the factory drivers in 1989-91, but turbos and management were a bit different those days. Lag is much less if you select the right turbo and map everything right. I will have all the details for you in a few months I hope!

I've never heard about the Digifant being used here. Yes the Marelli-Weber system is from the old Cosworth Sierra rwd. Those cars were 204hp stock, with great tuning potential. Their management system suits the 1.8T just fine with remapping, distributor change and the addition (welding) of 4 teeth on the ouside of the crank pulley, which give timing signals to the ecu. You'll be surprised to know that the Cosworth distributor is almost a drop-in on the Alfa engine! Very-very similar to our parts. In my case, I managed to fit the distributor innards in an Alfa distributor and I must admit, looks like real oem now!
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Re: 4-cylinder turbo performance

Post by Giuliettaevo2 » Mon Sep 07, 2009 1:58 am

Here in Holland there are quite a few too. :wink:

I know someone who had a few of these engines for sale not too long ago. www.alfanord.nl ( dutch site...)

The digifant was an easy solution apparantly, a guy i know used it way back in 1995 for his racecar. Finding a VW-guy to chip it was the most difficult he told me. Later they switched to the Magneti Marelli as used on the 155Q4.

One of the racers over here uses kdfi, that is sort of a megasquirt system, and is quite enthousiastic about it.

A few years ago i owned a 75 1.8Tb which i stripped for parts because the entire car was kept together by rust... :shock: I still curse myself for selling the engine.. :evil: I loved driving the Tb, the window always a little bit opened to hear the turbo come on song :) . especially in the rain it was very entertaining to drive.

Real '80s turbo car, nothing happens off boost but when the boost comes in it turn's into a tiger. 8)
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Re: 4-cylinder turbo performance

Post by SydneyJules » Mon Sep 07, 2009 3:00 am

I can say from my experience in the silver Alfetta GT, that even with the comp ratio pretty low (less than 8:1- can't remember exact- maybe 7.8:1), the modern turbo, at that stage an external wastegate, off the shelf GT25 with a smallish exhaust housing, suited the engine perfectly. It pulled from part throttle and low revs with the sort of urge that makes a V6 feel dull- no lag, no light switch response. And when it cames on boost, it hunted the redline down like my cammed 2.5, while spinning the wheels through 3rd. ECU was an Autronic SM4 at that stage. The head had porting and valve work done too- which may help things? I don't know.... but I remember copmaring it my mate's modded Turbo 2002 (not factory), another's RX2 with a 13B, and a warmed up 2000 WRX STi with 300hp at 4 wheels- the GT was quicker, sounded better and looks effortlessly better... Mind you, it's now got monoblock liners and a massive HKS turbo on it.... I don't know if it's still as sweet as it was, possibly a bit peakier now. That car is amazing, either way.

Yep. A chrome bumpered pre-70 GTV, in an outlandish 70s baby blue, modern wheels, and a 250-300hp 1.8t with a modern turbo and FMIC would be the ultimate- it even has the original Nord sound... plus wastegate flutter..... :roll:

Got a V6 to finish first! :oops:

The 1.8t has got to be the ultimate budget alfa engine, or so I could imagine-

Exhaust, turbo back, boost to 15psi, aftermarket ECU... the things should come reasonably close to 200hp before you even get serious- what did they make stock? 140hp? I've never seen many stock ones, but seeing the way the Silver car's one deals with boost and RPM, it's clear that's the way forward with them!
Fixing it bit by bit....
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Re: 4-cylinder turbo performance

Post by Jim K » Mon Sep 07, 2009 4:01 am

The 1.8T had 155hp std and 23kgm (166ftlbs) at 2600rpm. Reportedly, with a simple chip change which pushed boost to ~1bar (~15psi) and a little more fuel (the allowable mods) the GpN version made 204hp and 30kgm (217ftlbs) at 4500rpm and this with the std CR, 7.5:1.
I have a feeling the modifying public in countries where this car was not introduced, may be 'kicking themselves in the a$$' for not being aware of the hidden potential, reliability and handling qualities of this 'rare' 75. It was introduced almost together with the TS, but sold much less in the same markets due to the public not being very boost-oriented those days and the fact it was never intended as a catalyst model.
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Re: 4-cylinder turbo performance

Post by Luis » Mon Sep 07, 2009 6:12 am

Turbos can be found in Spain too.


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Jim K
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Re: 4-cylinder turbo performance

Post by Jim K » Mon Sep 07, 2009 8:33 am

Very good Luis, thanks for posting this.
You can all now compare the features of these two cars and even if you don't speak Spanish (neither do I) the tables are easy to understand.
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Re: 4-cylinder turbo performance

Post by jamal555 » Mon Sep 07, 2009 10:20 am

nice, i didnt know turbos were made with narrow stripe... or normal bumpers...

a saw few in italy with normal bumpers...

mine is the amerika model with wide ts strip and heavy suspended bumpers... that are coming off in near future... :)

this was actually series 1 turbo... 1986-87? mine is from december 1989...
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Re: 4-cylinder turbo performance

Post by TNT » Mon Sep 07, 2009 10:44 am

i think this is the 1.8T which Jim mentioned in the other topic.
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