Fiat race engine. no horsepower.

Competition engines and ancillaries - general discussion
ladapowah
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Fiat race engine. no horsepower.

Post by ladapowah » January 23rd, 2014, 12:08 pm

Hello..

I have this Fiat ritmo Abarth 130tc engine that I don`t get the right horsepower from..
and I Wonder what is wrong?

The engine is bought so I dont know the whole story
but I do know:

It is a Fiat Abarth 130tc engine converted to RWD in a Lada With Fiat 4trins gearbox

The engine head is nicely ported, not much.
original valves.
The head is machined 2-3mm I think to get closer the pistons. is also machined for clearance for the pistons.
Pistons are from Alfa Romeo I think, big round dome. 84mm.

The cams have a duration on 310. Intake is adjusted to 109.5 and exhaust 109.5.

The exhaust is 4-2-1. 2,5" end.

The intake is OBR manifold With dellorto 45 drla.
ported to fit the head.
dellorto has 38 venturis, 180 main and 200 air, 45 pump jet.
adjusted air screws With gunson colortune..

The crankshaft and rods is balanced and goes smooth.
I haven`t check the valves springs.

This engine had 116hp on the wheels. 136hp in the engine..
6 horsepower more than original..

I have other engines that I have built and they have 140hp and 170hp.
but this engine I cannot figure out, im looking for 160hp in the engine,
missing 24hp..

What can be wrong?

Best regards:
Karl Helland
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Guy Croft
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Re: Fiat race engine. no horsepower.

Post by Guy Croft » January 23rd, 2014, 1:40 pm

Are these cams regrinds?


Please state type/make anything you know about them..

G
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ladapowah
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Re: Fiat race engine. no horsepower.

Post by ladapowah » January 23rd, 2014, 6:10 pm

No they are not regrinds.. only number I found was O22..
have a picture of them.
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Guy Croft
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Re: Fiat race engine. no horsepower.

Post by Guy Croft » January 24th, 2014, 11:21 am

OK, what cam timing have you set them at (full lift)

eg: 108 inlet 110 ex

Your jetting is miles out by the way but I will come on to that later. Your pistons are covered in carbon whihc is either over-rich or worn rings = massive oil consumption. Have you done a hot compression test with all plugs out and throttle wide-open?

What is the ex manifold design and silencers.

Good photos thanks - but try and give the tech detail!

G
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Re: Fiat race engine. no horsepower.

Post by Urbancamo » January 24th, 2014, 3:31 pm

Hello

Do you have calculated the CR with those ridiculously big domed pistons? It must be high even if you have skimmed head too! The engine must detonate like a pig and your pistons seem have to have lots of detonation marks.

Also no squish areas left in the head. Doesn't make much sense ruining the Fiat TC superior head design with something like that.

I have 2 litre unit in my garage wich is producing 170 bhp/200 Nm torque with mild 280 deg. regrinded cams/45 DHLA's 36 mm chokes so something is definitely wrong.

I would start up by measuring the compression in every cylinder!

TH
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TomLouwrier
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Re: Fiat race engine. no horsepower.

Post by TomLouwrier » January 24th, 2014, 4:06 pm

hi all,

Given that the pistons are suspected ex-Alfa, it would be logical that whoever fitted them tried to copy the Alfa Nord's hemi chambers to go with them. How effective this is in a Fiat head with ports and valves that were designed for another chamber and piston combo altogether? I doubt it. I don't really like the big dome / no squish Alfa anyway but that is a matter of taste as much as reason.
I've seen Guy worked on Alfas so he can comment first hand on that design.

You may very well be better off with good unmodified Fiat head and pistons and start from scratch.

regards
Tom
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ladapowah
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Re: Fiat race engine. no horsepower.

Post by ladapowah » January 24th, 2014, 7:02 pm

Oki thanks for answear.

G, the cams are: 110 inlet and 110 ex..
What do you recomend for jets for that engine ?
When I had the car in a dyno i tried out 165main jets, we had to stop the run on 5000rpm because it got dangerous litle fuel..
so we had to go up in main jets,

the exhaust size i dont remember, had a smaller exhaust on before, same size as the Fiat ritmo 130tc fwd have. 4-2-1.. 2" end.. 1 silencer.. same hp (116hp)
But builded a new exhaust system, a size bigger all the way 4-2-1.. 2.5" end.
1 silencer.. same (116hp)

No I haven`t done a compression test,
will take that test on every cylinder


I think I should just strip the engine and build a new engine with the good parts..
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Guy Croft
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Re: Fiat race engine. no horsepower.

Post by Guy Croft » January 25th, 2014, 12:40 pm

What make are the cams?

Have I missed this?

G
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ladapowah
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Re: Fiat race engine. no horsepower.

Post by ladapowah » January 26th, 2014, 9:04 pm

G

I have no idea what the make is on these cams..
only number ifound was O22..
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Guy Croft
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Re: Fiat race engine. no horsepower.

Post by Guy Croft » January 27th, 2014, 12:51 pm

OK - cams, thanks. They do look like a decent billet type.

Jetting on 38mm chokes should be nearer to:

145 main
175 air corrector

emulsion tube - not entirely sure of this, I think No6 in DRLA45s

The ignition timing should be 34-36 deg total at 5500rpm..

Cannot otherwise explain the very low power unless the rings and bores are so worn it's got no compression..

G
Guy Croft, owner

ladapowah
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Re: Fiat race engine. no horsepower.

Post by ladapowah » January 31st, 2014, 11:22 am

Oki..

Checked the compression today.. it was in PSI: 190 - 185 - 190 - 180
a bit low ? should it be 200-210 ?

The emulsion tube was No2.
Have ordered new jets for the dellorto`s..
A question of topic G. Why do you use Weber 44 idf istead of dellorto drla 45 ?

KH
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Guy Croft
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Re: Fiat race engine. no horsepower.

Post by Guy Croft » January 31st, 2014, 1:18 pm

Those compressions (if hot engine) are NOT the fundamental cause of the low power.

I use IDF on RWD Fiat when requested to - usually because sidedrafts won't fit or for historic authenticiy..

G
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Re: Fiat race engine. no horsepower.

Post by Urbancamo » January 31st, 2014, 2:06 pm

What is your fuel pump by the way? Are you sure its capable of supplying enough fuel volume? Your jetting is way off and it still runs lean. Something doesn't quite match up.
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Guy Croft
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Re: Fiat race engine. no horsepower.

Post by Guy Croft » February 1st, 2014, 12:15 pm

Just realised what is also wrong - probably fudamental cause.

Chokes too big. Go down to 36mm.

G
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ladapowah
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Re: Fiat race engine. no horsepower.

Post by ladapowah » February 2nd, 2014, 8:24 pm

Oki. thanks for reply`s.

The fuel pump should deliver enough, I have drove the car at full throttle with 1-2-3 gear without emptying the carbs for fuel or something..
but I will check it :)

Have got some 36mm chokes now, just waiting for the smaller jets.
I will also check my intake manifold to see if I have done something wrong,
and test some Dellorto 45 DHLA with GC intake manifold.
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