guy hi.
i'd like to hear your advise for fitting big valves on my 130 tc,whats the best comb of valve dia 45-36 or 45-40 to accieve more flow?.the ports are all ready polished to 33.5mm and head is 1mm lower to rise the com.but the last head gasked blow cost me annother 0.5mm.the cams are the alquati 494.what is the most common angle cut on this valves?
concider the car runs a lot of 1/4 miles and it's not a daily car.
thanks a lot for the side and the infos that you supply.
whith regards dafnos
Fiat 130TC big valve conversion question
-
Guy Croft
- Site Admin
- Posts: 5039
- Joined: June 18th, 2006, 9:31 am
- Location: Bedford, UK
- Contact:
OK,
Firstly, Dafnos, my cold technical style is just my 'way' and not intended to hurt anyone's feelings. The world of the race engine is a cold and brutal thing and pretending it's not won't fool anyone for long. So I am not just going to answer 'go to 45/40 valves' because 'one-liners' is not what this race engine website is about and no-one else reading that will learn anything useful from it.
I do very detailed engine specs. There is no such thing as best valves. It all depends on bhp target and budget. Big valve conversions are expensive and you don't do them unless you have to. A bigger valve wil tend to give more flow everywhere, but the bigger it is the higher you have to lift it to capitalise on the flow potential of the ports. This is because the the bigger the valve the worse its discharge coefficient.
I've had 182bhp @ 7000rpm, 148lbf ft @ 5500rpm on GC 3A cams, about 10.4mm lift running 45 DCOE on 38mm chokes on a 2.1L TC. That was a 130TC head flowing only 107cfm at 10.4mm lift at 10".
A GC prepped 130TC head will flow not less than 110cfm @ 10" at around 12mm lift. (see http://guy-croft.com/viewtopic.php?t=139)
Your 33.5mm ports are too small for this but running 494 cams on full spec motor with 43.5mm/36mm valves (race rods, pistons etc) on 45s, with a GC spec race exhaust system (long branch 4-1) you're going to see around 190bhp @ 7600 with say 148lbf ft at 5800. So very high rpm involved there.
But I would not use those cams for 1/4mile, they are a long circuit cam, far too peaky & not enough torque for sprint.
Whether you think they are good or not is neither here nor there, like I said before, you don't build an engine around the cams. That's what being a race engine builder is - getting the engine fit for purpose. No point in setting up that motor at less than full race spec (rods, flywheel, clutch, pistons, dry sump) because you're either going to have to keep the revs below 7200and never 'realise' the power, or it's just going to explode.
Another example: 45/40 valves (I don't use 46mm any more) with 494 cams a GC spec race motor - without going big bore - is going to take you to 198-200bhp @7750rpm, with 149lbf ft or more at 6000, running comfortably every race to 8500 and higher. We ran a motor like that in 1994 in NHRA. I am reading the dyno specs as I write. There are however much more powerful specs than that though, the 494 torque characteristic is poor by my standards compared with other combinations I have determined thru painstaking dyno and track test.
But any engine built to my standard like that is going to cost you over well ‚£8,000 for the short unit not even including the huge list ancillary equipment that it needs around it - and that's not even talking suspension and brakes etc etc. If you think that's too much take a look at other top engine builders like Wilcox and Mountune. The backyard experts do 'cheap', they don't give the performance (nowhere near) and their engined break and you pay twice. I see this all the time and all my friends in race engine prep are suffering from it. Every good engine builder works the way I do with race engines setups & costs, from Clubman to F1. You have not detailed at all your current motor spec, target, existing bhp/torque/rpm characteristic or budget.
GC
Firstly, Dafnos, my cold technical style is just my 'way' and not intended to hurt anyone's feelings. The world of the race engine is a cold and brutal thing and pretending it's not won't fool anyone for long. So I am not just going to answer 'go to 45/40 valves' because 'one-liners' is not what this race engine website is about and no-one else reading that will learn anything useful from it.
I do very detailed engine specs. There is no such thing as best valves. It all depends on bhp target and budget. Big valve conversions are expensive and you don't do them unless you have to. A bigger valve wil tend to give more flow everywhere, but the bigger it is the higher you have to lift it to capitalise on the flow potential of the ports. This is because the the bigger the valve the worse its discharge coefficient.
I've had 182bhp @ 7000rpm, 148lbf ft @ 5500rpm on GC 3A cams, about 10.4mm lift running 45 DCOE on 38mm chokes on a 2.1L TC. That was a 130TC head flowing only 107cfm at 10.4mm lift at 10".
A GC prepped 130TC head will flow not less than 110cfm @ 10" at around 12mm lift. (see http://guy-croft.com/viewtopic.php?t=139)
Your 33.5mm ports are too small for this but running 494 cams on full spec motor with 43.5mm/36mm valves (race rods, pistons etc) on 45s, with a GC spec race exhaust system (long branch 4-1) you're going to see around 190bhp @ 7600 with say 148lbf ft at 5800. So very high rpm involved there.
But I would not use those cams for 1/4mile, they are a long circuit cam, far too peaky & not enough torque for sprint.
Whether you think they are good or not is neither here nor there, like I said before, you don't build an engine around the cams. That's what being a race engine builder is - getting the engine fit for purpose. No point in setting up that motor at less than full race spec (rods, flywheel, clutch, pistons, dry sump) because you're either going to have to keep the revs below 7200and never 'realise' the power, or it's just going to explode.
Another example: 45/40 valves (I don't use 46mm any more) with 494 cams a GC spec race motor - without going big bore - is going to take you to 198-200bhp @7750rpm, with 149lbf ft or more at 6000, running comfortably every race to 8500 and higher. We ran a motor like that in 1994 in NHRA. I am reading the dyno specs as I write. There are however much more powerful specs than that though, the 494 torque characteristic is poor by my standards compared with other combinations I have determined thru painstaking dyno and track test.
But any engine built to my standard like that is going to cost you over well ‚£8,000 for the short unit not even including the huge list ancillary equipment that it needs around it - and that's not even talking suspension and brakes etc etc. If you think that's too much take a look at other top engine builders like Wilcox and Mountune. The backyard experts do 'cheap', they don't give the performance (nowhere near) and their engined break and you pay twice. I see this all the time and all my friends in race engine prep are suffering from it. Every good engine builder works the way I do with race engines setups & costs, from Clubman to F1. You have not detailed at all your current motor spec, target, existing bhp/torque/rpm characteristic or budget.
GC
-
dafnos
head cfm...
guy hi again....
you dont hurt my feelings and you don't got a cold technical style you are a profesional and i use this way in my jop to and i want to believe everyone does.....
so the bugdet is the last thing that i concider not because i'm a welthy man but i just don't care.i'm asking for some technical tricks so i can take the best from the engine.my machinist in cyprus use a flowbench to develop heads for race,drag.rally etc. but he is not expert on this heads (tc fiats) because are to old and very bad famed in cy. and it's not the best thing to guess what to do if you dont know how to increase cfm rate.(only a few people get the time to deal with this cars in cy).and as you said something if it gets right you won't have to do it again.so the reason that i'm asking you this details is that i can't experiment on and on and the result is a bad shaped head with a no come back
condition.the target is 190-200 bhp i know i ask a lot but...
i never get the car on a dyno before.
you dont hurt my feelings and you don't got a cold technical style you are a profesional and i use this way in my jop to and i want to believe everyone does.....
so the bugdet is the last thing that i concider not because i'm a welthy man but i just don't care.i'm asking for some technical tricks so i can take the best from the engine.my machinist in cyprus use a flowbench to develop heads for race,drag.rally etc. but he is not expert on this heads (tc fiats) because are to old and very bad famed in cy. and it's not the best thing to guess what to do if you dont know how to increase cfm rate.(only a few people get the time to deal with this cars in cy).and as you said something if it gets right you won't have to do it again.so the reason that i'm asking you this details is that i can't experiment on and on and the result is a bad shaped head with a no come back
condition.the target is 190-200 bhp i know i ask a lot but...
i never get the car on a dyno before.
-
Guy Croft
- Site Admin
- Posts: 5039
- Joined: June 18th, 2006, 9:31 am
- Location: Bedford, UK
- Contact:
Let me tell you how this works. It's not off topic, it's very much to do with it, because you want a complex job doing and there many uncertainties for you. So I am going to use your topic as a vehicle to do a bit of good-old GC tuition here.
No-one has an unlimited budget but that is not the point. Everyone has A budget. It may ‚£500 or ‚£15000, the limit on your credit card, a bank loan, money in a building society or whatever. The engine should always represent not less than one-third of the total cost of prepping a competition car.
You have to disclose to your engine guy what you can spend, it maybe a bit each month over 6 months or so. People say to me 'oh but if I tell you - you'll take it all'. Not so. I never worked like that"! As far as GCRE is concerned, because my estimates proved such invaluable aide-memoires to people, in terms of taking their engines somewhere else and saying 'Guy Croft says it needs all this..', I won't write them unless I have the job in here and can bill for strip inspect and report. And they are copyright. That is how bad it is.
My Laptop is littered with speculative costings, they take hours and I never got a single job from a speculative costing, except in one case where the client had me running round in circles with he chopping and changing it about 10 times before he went ahead. Then he was, frankly, a real nuisance. I think I spent more time writing for him than doing his engine, not good. In all the years I've been doing this only once has a client rang up and said 'I've got ‚£xxxx amount saved up and I am going to spend it on my engine'. Well done that man. More often it's a battle to get the truth out of people.
A budget - Hard to live with maybe, but true. If you have never been asked this before, you need to start thinking about it. The guy who is doing - he has to work out what to do and cost it inside budget. If he isn't told what the budget is it's impossible. If he doesn't know how to do it, he shouldn't be doing it. And, if it's not done to a written budget identifying what is going to be undertaken and how - then you don't know what you're getting. The 'race engine' market in the UK has become so corrupted by a total failure of many to operate this way. I hear all the stories, yes. In fact I am putting the final touches to a proposal to the FER - Federataion of Engine Manufacturers, est 1937 - to open a 'Race Engine Division' within the Federation for properly accredited race engine builders who DO work this way!
Technically if you are having the work done by your Cyprus contact I can offer little else beyond that which I have already said, I've told you roughly how your get to 200bhp, follow the steps I have id'd. Here is a typical list of a StII unit, rally cams standard valve size. In your case add big valve conversion and you're halfway there.
ENGINE FULL STRIP, INSPECT AND REPORT
BLOCK REFACE
ENGINE AND PARTS CHEMICALLY CLEAN, BLOCK /ANCILLARIES PAINT
CORE PLUGS FITTED
RE BORE AND MICRO HONE
MODIFY AUX DRIVESHAFT INC SHORTEN FOR 1‚ BELT
RACE RODS
FORGED PISTONS AND RINGS
CLEAN, TAP AND PLUG CRANK OIL GALLERIES
CRANK JOURNALS POLISH IF OK
MODIFY CRANK OILWAYS
REFACE FLYWHEEL
CLUTCH UPRATED ORGANIC
LIGHTEN FW AND BALANCE CRANK FW
BEARINGS MAIN AL TIN
BEARINGS ROD AL TIN
BEARING THRUST AL TIN
HEAD REFACE
VALVE GUIDES RACE
NEW VALVES GC RACE SET 42/36
IN/EX SEATS REGRIND RACE
RECESS INLET SEATS TO ALLOW REFACING OF HEAD
FULL COMBUSTION CHAMBER RELIEF AND POLISH
MOD COOLANT GALLERIES
RACE SPEC GASFLOW HEAD
GC S/D Fiat MANIFOLD TO RACE CARBS
FITTING KIT
VALVE SPRINGS RACE GC
SHIMS SET TO BUILD
CAMS GC 3A
CAMWHEELS RACE TO 1‚ BELT
GC CAMBELT 1‚Â
HEAD GASKET POLYMER GOETZE
FULL SET OTHER GASKETS/SEALS FULL ENGINE INCL HIGH TEMP SEALS
HEAD BOLTS GC RACE
FW BOLTS OE SET
FIXINGS (NUTS AND BOLTS ETC)
2 LITER WATER PUMP
TOOTHED BELT DRIVE ALTERNATOR/PUMP
DISTRIBUTOR OVERHAUL & LUMENITION KIT
OIL PUMP OVERHAUL AND POLYMER COAT
RACE SUMP (BIG WING)
MOROSO ACCUMULATOR, OIL COOLER, REMOTE FILTER AND ACCESSORIES
RACE PLUGS
BUILD COST ST II
All you have to do is tick what you want and give it to your guy. The guy can get in touch with me by e mail any time he wants, I may know him. I would welcome comments from other members here, re what I have said about budget and spec and how they are related.
GC
No-one has an unlimited budget but that is not the point. Everyone has A budget. It may ‚£500 or ‚£15000, the limit on your credit card, a bank loan, money in a building society or whatever. The engine should always represent not less than one-third of the total cost of prepping a competition car.
You have to disclose to your engine guy what you can spend, it maybe a bit each month over 6 months or so. People say to me 'oh but if I tell you - you'll take it all'. Not so. I never worked like that"! As far as GCRE is concerned, because my estimates proved such invaluable aide-memoires to people, in terms of taking their engines somewhere else and saying 'Guy Croft says it needs all this..', I won't write them unless I have the job in here and can bill for strip inspect and report. And they are copyright. That is how bad it is.
My Laptop is littered with speculative costings, they take hours and I never got a single job from a speculative costing, except in one case where the client had me running round in circles with he chopping and changing it about 10 times before he went ahead. Then he was, frankly, a real nuisance. I think I spent more time writing for him than doing his engine, not good. In all the years I've been doing this only once has a client rang up and said 'I've got ‚£xxxx amount saved up and I am going to spend it on my engine'. Well done that man. More often it's a battle to get the truth out of people.
A budget - Hard to live with maybe, but true. If you have never been asked this before, you need to start thinking about it. The guy who is doing - he has to work out what to do and cost it inside budget. If he isn't told what the budget is it's impossible. If he doesn't know how to do it, he shouldn't be doing it. And, if it's not done to a written budget identifying what is going to be undertaken and how - then you don't know what you're getting. The 'race engine' market in the UK has become so corrupted by a total failure of many to operate this way. I hear all the stories, yes. In fact I am putting the final touches to a proposal to the FER - Federataion of Engine Manufacturers, est 1937 - to open a 'Race Engine Division' within the Federation for properly accredited race engine builders who DO work this way!
Technically if you are having the work done by your Cyprus contact I can offer little else beyond that which I have already said, I've told you roughly how your get to 200bhp, follow the steps I have id'd. Here is a typical list of a StII unit, rally cams standard valve size. In your case add big valve conversion and you're halfway there.
ENGINE FULL STRIP, INSPECT AND REPORT
BLOCK REFACE
ENGINE AND PARTS CHEMICALLY CLEAN, BLOCK /ANCILLARIES PAINT
CORE PLUGS FITTED
RE BORE AND MICRO HONE
MODIFY AUX DRIVESHAFT INC SHORTEN FOR 1‚ BELT
RACE RODS
FORGED PISTONS AND RINGS
CLEAN, TAP AND PLUG CRANK OIL GALLERIES
CRANK JOURNALS POLISH IF OK
MODIFY CRANK OILWAYS
REFACE FLYWHEEL
CLUTCH UPRATED ORGANIC
LIGHTEN FW AND BALANCE CRANK FW
BEARINGS MAIN AL TIN
BEARINGS ROD AL TIN
BEARING THRUST AL TIN
HEAD REFACE
VALVE GUIDES RACE
NEW VALVES GC RACE SET 42/36
IN/EX SEATS REGRIND RACE
RECESS INLET SEATS TO ALLOW REFACING OF HEAD
FULL COMBUSTION CHAMBER RELIEF AND POLISH
MOD COOLANT GALLERIES
RACE SPEC GASFLOW HEAD
GC S/D Fiat MANIFOLD TO RACE CARBS
FITTING KIT
VALVE SPRINGS RACE GC
SHIMS SET TO BUILD
CAMS GC 3A
CAMWHEELS RACE TO 1‚ BELT
GC CAMBELT 1‚Â
HEAD GASKET POLYMER GOETZE
FULL SET OTHER GASKETS/SEALS FULL ENGINE INCL HIGH TEMP SEALS
HEAD BOLTS GC RACE
FW BOLTS OE SET
FIXINGS (NUTS AND BOLTS ETC)
2 LITER WATER PUMP
TOOTHED BELT DRIVE ALTERNATOR/PUMP
DISTRIBUTOR OVERHAUL & LUMENITION KIT
OIL PUMP OVERHAUL AND POLYMER COAT
RACE SUMP (BIG WING)
MOROSO ACCUMULATOR, OIL COOLER, REMOTE FILTER AND ACCESSORIES
RACE PLUGS
BUILD COST ST II
All you have to do is tick what you want and give it to your guy. The guy can get in touch with me by e mail any time he wants, I may know him. I would welcome comments from other members here, re what I have said about budget and spec and how they are related.
GC
-
dafnos
the useful book...
guy thanks for the reply ! it's big and useful!!!
you are right about the way that some "tuners" or "engine builders" act and they are the most famus for some reason but thats another story...anyway..
some months ago i searched for your book at bookstores and internet and i could't find anything at all! it's out of print they said, do you have anytging left? i'm interested..price? i believe that it will be more easy to read the instructions from bother you all the time with 1st grade questions! :oops: and as you said : you have a lot of work to do and one pair of "miraculous" hands
8)
ps.
if anyone wants to sell the book tell me or for anything personal reasons email me(you can find it at the members list)
continue the good work boys!!!!!! :)
you are right about the way that some "tuners" or "engine builders" act and they are the most famus for some reason but thats another story...anyway..
some months ago i searched for your book at bookstores and internet and i could't find anything at all! it's out of print they said, do you have anytging left? i'm interested..price? i believe that it will be more easy to read the instructions from bother you all the time with 1st grade questions! :oops: and as you said : you have a lot of work to do and one pair of "miraculous" hands
8)
ps.
if anyone wants to sell the book tell me or for anything personal reasons email me(you can find it at the members list)
continue the good work boys!!!!!! :)
-
sumplug
- Posts: 234
- Joined: June 25th, 2006, 10:25 am
- Location: Banned 4th Oct 07 by GC
- Contact:
-
Guy Croft
- Site Admin
- Posts: 5039
- Joined: June 18th, 2006, 9:31 am
- Location: Bedford, UK
- Contact:
GC 3A is 10.8 nominal lift, Alquati 494 12.25 nom. Both run 0.4, 0.45mm running clearance or tighter.
The durations of these 2 high acceleration cams are roughly similar roundabout 300 crank deg but 494 has a lot more lift around tdc, 5-5.5, 3A about 3.4mm. The 494 has a narrow powerband, pretty poor torque below 4800, peak torque around 6500, peak power 7600, and will race to over 8500 on the right TC 2 liter. The 3A is much more driveable, will pull from 2800, peak torque around 5500, peak power 7-7200 but starts to 'run out of steam' about 8000. The 494 is definitely a long circuit cam, great in a straight line and long corners where you can keep the motor on the pwerband, the 3A's driveability can make for a quicker car with the right driver.
I don't get too involved in super accurate quotes of duration and lift, all depends what the individual valve is shimmed at.
GC
The durations of these 2 high acceleration cams are roughly similar roundabout 300 crank deg but 494 has a lot more lift around tdc, 5-5.5, 3A about 3.4mm. The 494 has a narrow powerband, pretty poor torque below 4800, peak torque around 6500, peak power 7600, and will race to over 8500 on the right TC 2 liter. The 3A is much more driveable, will pull from 2800, peak torque around 5500, peak power 7-7200 but starts to 'run out of steam' about 8000. The 494 is definitely a long circuit cam, great in a straight line and long corners where you can keep the motor on the pwerband, the 3A's driveability can make for a quicker car with the right driver.
I don't get too involved in super accurate quotes of duration and lift, all depends what the individual valve is shimmed at.
GC
- Attachments
-
- Cam maps lift by cam degrees of rotation with flat-follower, GC 3A, Alquati 494.
- GC3A vs 494.jpg (131.86 KiB) Viewed 6019 times
Who is online
Users browsing this forum: No registered users and 12 guests