Fiat 2.0 TC will not pull over 6000

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Andy007
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Fiat 2.0 TC will not pull over 6000

Post by Andy007 » November 26th, 2006, 12:48 am

At first excuse for my bad English, but I hope anyone can help with my problems on my 1985 Fiat 124 Spider 2.0

The motor runs great from 2000 to 6000 rev/min but will not pull up to 7000 rev/min.

The engine is:

Fiat 2.0 Twincam with 36.0 / 43.5 valves, ported/polished head - machined 0.5mm, standard pistons, all parts balanced, lightened flywheel, reground cams 290 degrees/10.3mm, valve lift at TDC 2.5mm, adjustable cam gears, twin Weber 40 idf with 35mm venturies, F11 emulsion tube, main jets 140, air correctors 180, ignition 35 degrees at 5500 rev/min, OE exhaust manifold with one straight-thru back silencer.

My wish is that the motor goes to 7000 rev/min, what do you think about horsepower in this specification ?

Guy Croft
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Post by Guy Croft » November 26th, 2006, 10:09 am

Sorry - but I can't see anything wrong with your spec. That setup should run OK on std CR.

Could it be it a fuel pump, ignition or rev-limiter problem? What exactly happens over 6000 rpm?

GC

BTW I cannot see the photos.

Andy007
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Does not go over 6000

Post by Andy007 » November 26th, 2006, 10:49 am

Hello GC,

thanks for your fast reply. This is the same i think, it must go up to 7000. After 6000, for example in 3rd. gear, the acceleration goes very , very slowly to 6500, for evective acceleration its better to go into 4. gear.

I have tested the Vmax on the highway, i drove the car about 3 kilometers with full throttle,and it runs all time with 6000, so i dont think it is the fuel pump ( electrical Mitsubota pump ).

Whats about the stock OE exhaust header, too small ?

I have also tested with different cam times, for example more Lift at TDC ( 3.5mm to 2.5mm ) The car drives better in higher rpm areas, but there is a big loss of torque, the acceleration is not so good .

Mistakes on the ignition, any tipps ?

What do you think about horsepower with these applications ?

You can see pics of the car under " Readers Cars", sorry for too big pictures.

Greets from Germany Andy007
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NOSferatu
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Post by NOSferatu » November 26th, 2006, 12:50 pm

I have had samekind of problems earlier, and I think that your problem is the standard exhaust manifold. One experiment showed that with 1600cc standard exhaust manifold secondaries engine started to pull from 5000rpm and stopped to pull at 6000 rpm. With 2 litre engine secondaries it pulled from 4000 to 8000!.
Worth a try!
If that is not the cause, I suggest to double check valve timing. I had problem with that also, as I misunderstood the instructions to adjust it right. I forgot to take valve clearance in account.

Andy007
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@NOSfeartu

Post by Andy007 » November 26th, 2006, 4:35 pm

Hello NOSferatu,

thanks for your tips about cam timing, I have checked the cam timing, valve clearance OK, timing OK.

The tip about exhaust manifold is too small is one of the same idea I think .

But I don't know a good manufacture to made a good exhaust manifold.

My car is a 1985 Pininfarina Spider with this special steering, only at the 1985 models. The exhaust manifold from the Spider to 1984 does not fit on my car, it makes trouble with my steering.

At GC, do you have a exhaust manifold for my car ?

Guy Croft
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Post by Guy Croft » November 26th, 2006, 6:25 pm

Andy, hi

I have deleted the under-engine photo. Please practise your photo technique before posting again, most readers do not have broadband. The problem with resizing is that you lose defintion and the picture becomes 'grainy'. It is better, when taking a photo of a large thing, to 'crop' it so that the image only captures the important info.

Sorry, but I do not do exhaust systems any more, too difficult to make them in very small numbers with accuracy. Different if you're making hundreds.

Yes, it is quite possible that your cams do not work with the OE ex manifold. So, try and get one made on the car.

As a 'rule of thumb' - I mean a very loose rule of thumb for a 4-2-1 you would want a combined primary and secondary length of 33".
And so the primaries should be say, 20" and secondary pipes 13". Or 19" primary and 14" secondary with primary always longer than secondary and not shorter than 17".

Every setup is different and the variance on lengths depends on inlet tract length - valve to rampipe, cam timing, overlap, cc and CR and many other things.
Get it right and the area under the torque-curve is totally optimised. This needs software. Get it wrong and the results vary from not-perfect to awful. My advice will not result in a disaster, and the result will tend to be far better than what you have now. Will it fix the problem? Cannot say for sure, but it won't hurt any.

Alternatively play safe and go for a 4-1 33" header.

There must surely be an exhaust specialist in Germany (yes, I know it's a huge country) who can make a system on the car? I'd like to hear more about these specialists outside the UK. In the UK there are many 'specialists' good and bad, I know the good names, and few they are.

If you took a trip to Lincoln, UK, I could identify the cause in minutes, but I guess that's pushing the bounds of credibility.

GC

Guy Croft
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Post by Guy Croft » November 26th, 2006, 6:43 pm

Hi Andy

in the course of checking your post I realise that your cams are reground, yes?

You will never , ever get a good torque characteristic from reground 8v TCs, I wasted a small fortune (‚£) learning this many years ago. I mean back in the 1980's. 'Experts' told me, 'yes regrinds are better'. What nonsense!

Sorry I missed this first time - get some billet cams.

GC

TR-Spider
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Post by TR-Spider » November 28th, 2006, 8:20 am

At http://www.gb-motorentechnik.de they sell a 4-1 for the 124 with rack-and-pinion steering, even with T’…œV (I think).

Thomas

branda
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Post by branda » November 30th, 2006, 11:21 am

TR-Spider wrote:At http://www.gb-motorentechnik.de they sell a 4-1 for the 124 with rack-and-pinion steering, even with T’…œV (I think).

Thomas
Thomas - I could really do with a manifold that works with a 2l in a 124 Spider with rack and pinion and that link looks good. Unfortunately, I don't speak any German and I wondered if you might be able to help? I don't want to hijack this thread but I have started another thread on the rack and pinion conversion at viewtopic.php?t=587

Many thanks,

Ben

sumplug
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Post by sumplug » November 30th, 2006, 4:09 pm

Hi Andy007


Having read this thread, I would also look to check that you are getting maximum ignition advance in the right place also.

Andy.

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