Being sick and tired of having Ford Escort RS2000s and Alfa GTAms pass me anytime on FIA Historic Race Championships with my 1608 124 Coupe, I decided to go on with a 2.0 lt project. Need your help guys!
My 1608 head flows rough 150hp with 42mm inlet and 38mm exhaust valves. I have a 2.0 lt engine from my 131 Racing and I thing to start working on the head. What valve sizes do you recommend to start with? 43 or 43.5mm inlets, what exhaust valves? What size head inlet ports and what size exhaust ports?
2.0 lt Race Head Prep
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So Cal Mark
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Joe Clemente
- Posts: 151
- Joined: Wed Jan 25, 2006 1:35 am
- Location: Vancouver, B.C. CANADA
Does your sanctioning body actually allow the use of a 2.0 litre engine in a 124 Coupe? As the car never came with a 2L I am curious to know how you can to do this. Are they that flexible with displacement?
As far as valves go, what else do you intend to do?
This is what we did on our 2L 124 Spider:
- 45mm intake
- 40mm exhaust
- moderate port work (avoid the ugly mistake of excessive material removal and altering port shape or you'll end up with an expensive piece of scrap aluminum that won't flow)
- Cams: 12.25mm of lift, 308 degrees of duration
- 44 IDFs (for Improved Production)
We also machined the valve seats, throat and performed very careful cuts around the valve to maximize flow. The car also ran over 12:1 compression and a host of other mods as well.
Keeping it in perspective: A Fiat 2L can be made to pruduce very good power even with standard valve sizes and other restrictions. Good head work and cams are key... John Baucom's SCCA E-Prod champ in 2000 is a perfect example of this. He or his father Gary would be very good persons to consult at Sports Car Authority in Matthews N.C. (If he's not racing in the Trans-Am series)
Cheers,
Joe
As far as valves go, what else do you intend to do?
This is what we did on our 2L 124 Spider:
- 45mm intake
- 40mm exhaust
- moderate port work (avoid the ugly mistake of excessive material removal and altering port shape or you'll end up with an expensive piece of scrap aluminum that won't flow)
- Cams: 12.25mm of lift, 308 degrees of duration
- 44 IDFs (for Improved Production)
We also machined the valve seats, throat and performed very careful cuts around the valve to maximize flow. The car also ran over 12:1 compression and a host of other mods as well.
Keeping it in perspective: A Fiat 2L can be made to pruduce very good power even with standard valve sizes and other restrictions. Good head work and cams are key... John Baucom's SCCA E-Prod champ in 2000 is a perfect example of this. He or his father Gary would be very good persons to consult at Sports Car Authority in Matthews N.C. (If he's not racing in the Trans-Am series)
Cheers,
Joe
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bandit
Re: 2.0 lt Race Head Prep
Hi Vassili
" with 42mm inlet and 38mm exhaust valves."
Did you mean 36mm Exhaust valves ? or did you go larger on them and
keep the intakes stock ?
If you can use a 2L in your Coupe are you allowed to use Side Drafts as well ? if so whats the size limits ? A side draft will add 10 to 15 HP on the top .
An Engine like what joe is taking about with 45mm In & 40 Ex Valves
and those Cams will need a min 45mm Carb with at least 42mm chokes .
The Largest Valves I've herd any use is 46 intake and 40 Exhaust .
A Fully built 2L can be a good power increase over a 1608 .
Dan
" with 42mm inlet and 38mm exhaust valves."
Did you mean 36mm Exhaust valves ? or did you go larger on them and
keep the intakes stock ?
If you can use a 2L in your Coupe are you allowed to use Side Drafts as well ? if so whats the size limits ? A side draft will add 10 to 15 HP on the top .
An Engine like what joe is taking about with 45mm In & 40 Ex Valves
and those Cams will need a min 45mm Carb with at least 42mm chokes .
The Largest Valves I've herd any use is 46 intake and 40 Exhaust .
A Fully built 2L can be a good power increase over a 1608 .
Dan
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Joe Clemente
- Posts: 151
- Joined: Wed Jan 25, 2006 1:35 am
- Location: Vancouver, B.C. CANADA
Dan,
with all due respect, carb barrel and choke sizing is not an automatic number depending on valve diameters. Additionally, we did not just plunk on a set of 44 IDFs through guess work or because we could not get anything bigger. IDFs were mandated for the car in that particular class. You're quite right that sidedrafts would work better and if Vassilis can get away with a 2L and sidedrafts, obviously better. Not necessarliy 45s though. Barrel sizing is a specific calculation and a secondary consideration to venturi diameter. Using bigger barrels won't garantee more power even with said modifications. Airflow and potential power comes from the correct choke sizing, yeah?
42mm chokes at least... ? Hmmm... last time I checked, choke sizes for 45 DCOEs were only available up to 40mm. Can someone verify this? Regardless, 42mm will kill any kind of low end flow. Too peaky. But one can debate this all day. Carburetion will simply need to be tested on both the dyno and the particular track.
Where we raced, the above setup was the best solution given the track characteristics. Honestly though, if we could have gotten away with sidedrafts then, we would have had them on in an instant and never looked back.
Regardless of this, I still would be interested in knowing how Vasillis can get away with a 2L in an old Coupe.
Cheers eh...
J.
with all due respect, carb barrel and choke sizing is not an automatic number depending on valve diameters. Additionally, we did not just plunk on a set of 44 IDFs through guess work or because we could not get anything bigger. IDFs were mandated for the car in that particular class. You're quite right that sidedrafts would work better and if Vassilis can get away with a 2L and sidedrafts, obviously better. Not necessarliy 45s though. Barrel sizing is a specific calculation and a secondary consideration to venturi diameter. Using bigger barrels won't garantee more power even with said modifications. Airflow and potential power comes from the correct choke sizing, yeah?
42mm chokes at least... ? Hmmm... last time I checked, choke sizes for 45 DCOEs were only available up to 40mm. Can someone verify this? Regardless, 42mm will kill any kind of low end flow. Too peaky. But one can debate this all day. Carburetion will simply need to be tested on both the dyno and the particular track.
Where we raced, the above setup was the best solution given the track characteristics. Honestly though, if we could have gotten away with sidedrafts then, we would have had them on in an instant and never looked back.
Regardless of this, I still would be interested in knowing how Vasillis can get away with a 2L in an old Coupe.
Cheers eh...
J.
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bandit
Joe
I agree with you on the matching Venturi and choke sizing , Vassili
was talking about a car ment for racing so on that note I was pointing
out how to get the most from an Engine with Valves and Cams close to
what your running on your own Car but if he could get away with the
side drafts instead and IDF's which can work really good .
I like the Cam Specs you sugguested . The TC I'm building is a close match to your own plus I had a feeling you were limited to IDF's for your class of racing but i was asking and making a point all in one on the 45 Sidedrafts which can go up to 42mm chokes .
Since he will not be running the Engine under 4 grand during a race
Chokes that big will be peeky yes but will also help with his top end
produce more HP and thats what he'll need to keep up with those
Escorts . The larger chokes will kill bottom end power but that shouldn't
be an issue i would think .
Even if he can't run a 2000 do to production ruling and so on maybe a
1800 would be a choice your racing rules will allow >?
Dan
I agree with you on the matching Venturi and choke sizing , Vassili
was talking about a car ment for racing so on that note I was pointing
out how to get the most from an Engine with Valves and Cams close to
what your running on your own Car but if he could get away with the
side drafts instead and IDF's which can work really good .
I like the Cam Specs you sugguested . The TC I'm building is a close match to your own plus I had a feeling you were limited to IDF's for your class of racing but i was asking and making a point all in one on the 45 Sidedrafts which can go up to 42mm chokes .
Since he will not be running the Engine under 4 grand during a race
Chokes that big will be peeky yes but will also help with his top end
produce more HP and thats what he'll need to keep up with those
Escorts . The larger chokes will kill bottom end power but that shouldn't
be an issue i would think .
Even if he can't run a 2000 do to production ruling and so on maybe a
1800 would be a choice your racing rules will allow >?
Dan
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vcg
1608 head has 38mm exhaust and 42mm inlet with 20-45-70 degree seats and really good port job. I use 44s with 36 venturis, and I am not allowed to use sides as I will have to move the servo, etc. With the two lt project I should use the 44s with 38 venturi or even better 48IDF, but I am not ready to invest on those yet.
My cams are Abarth Profilo68 the real stuf that Fiat used in 72-3 and 73-4 Rally championship. It's not a circuit cam profile, but a rally one, but is the best accelaration cam profile one can get I believe. Only 11mm full lift but 4.70 at TDC! 93 overlap, and 298 duration works phenominally well having full lift at 99in and 100.5ex degrees.
Regarding 2.0 lt on a BC1, well, the hologation is only for one engine the 1608, not even the 1596 or the 1756, BUT: I am competing at 1/B4 class that is 1969 with 1601-2000cc, and since I cannot rebore a 1608 block I can use a 2.0lt one of same specs provided that I don't go over 2000cc. These means that I cannot use the wonderfull 85mm 12:1 Borgo pistons...
My cams are Abarth Profilo68 the real stuf that Fiat used in 72-3 and 73-4 Rally championship. It's not a circuit cam profile, but a rally one, but is the best accelaration cam profile one can get I believe. Only 11mm full lift but 4.70 at TDC! 93 overlap, and 298 duration works phenominally well having full lift at 99in and 100.5ex degrees.
Regarding 2.0 lt on a BC1, well, the hologation is only for one engine the 1608, not even the 1596 or the 1756, BUT: I am competing at 1/B4 class that is 1969 with 1601-2000cc, and since I cannot rebore a 1608 block I can use a 2.0lt one of same specs provided that I don't go over 2000cc. These means that I cannot use the wonderfull 85mm 12:1 Borgo pistons...
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vcg
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Joe Clemente
- Posts: 151
- Joined: Wed Jan 25, 2006 1:35 am
- Location: Vancouver, B.C. CANADA
Uuhh... no Vassilis. Aside from the new seats and some deshrouding it isn't necessary to re-engineer the head. The main concern we had with bigger diameter valves and bigger cam lift was piston clearance. Fly cutting thr piston tops may well be necessary.
Dan,
In an ideal situation the motor may not need to see under 4K rpm. In reality, that isn't always the case. Again, it will depend on the track. That is really where that determination will be of value. A fellow local Fiat racer I know and another Honda buddy of mine have been suffering from using the wrong setup for the particular track on which we normally run. They both still labour under the illusion that bigger carbs and lots of cam are the standard all purpose race formula. Both are over carbed and over cammed and neither listen to helpful advice then wonder why their cars are both dogs on the track. Regarding those cam specs, 12.25mm is actually less than I've seen on some good SCCA engines. The major power gains require more, try 13-13.5mm Almost de rigueur in order to wrench out big #s.
BTW Dan what are you building for? Race?
Cheers
Joe
Dan,
In an ideal situation the motor may not need to see under 4K rpm. In reality, that isn't always the case. Again, it will depend on the track. That is really where that determination will be of value. A fellow local Fiat racer I know and another Honda buddy of mine have been suffering from using the wrong setup for the particular track on which we normally run. They both still labour under the illusion that bigger carbs and lots of cam are the standard all purpose race formula. Both are over carbed and over cammed and neither listen to helpful advice then wonder why their cars are both dogs on the track. Regarding those cam specs, 12.25mm is actually less than I've seen on some good SCCA engines. The major power gains require more, try 13-13.5mm Almost de rigueur in order to wrench out big #s.
BTW Dan what are you building for? Race?
Cheers
Joe
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bandit
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Joe Clemente
- Posts: 151
- Joined: Wed Jan 25, 2006 1:35 am
- Location: Vancouver, B.C. CANADA
Dan,
The TC you're building sounds like it'll be killer but be careful. If it has specs close to what I described earlier then I might suggest re-evaluating its intended use. OK for race but running cams and induction like that on the street will make you hate your car. The reason I say that is because this is definitely not a tractable combination. No good for sitting gridlocked on the I-5...
Then there is the little matter of emissions compliance... You live in L.A.?:lol:
Salut!
J.
The TC you're building sounds like it'll be killer but be careful. If it has specs close to what I described earlier then I might suggest re-evaluating its intended use. OK for race but running cams and induction like that on the street will make you hate your car. The reason I say that is because this is definitely not a tractable combination. No good for sitting gridlocked on the I-5...
Then there is the little matter of emissions compliance... You live in L.A.?:lol:
Salut!
J.
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bandit
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Joe Clemente
- Posts: 151
- Joined: Wed Jan 25, 2006 1:35 am
- Location: Vancouver, B.C. CANADA