Hi all
I have a 2 liter pinto 205 block, lightened flywheel, cvk 38 mm bike carbs with megajolt
I am planning my winter upgrades now and have already started working on a spare head I have. The valve throats are 37mm standard so can open them up
fairly easily so no need for a big valve head. I'm having the head skimmed just not sure how much ? Any ideas out there guys ? 1 mm is apparently
conservative and you can get up to 1.5 mill skimmed.
The ports are being opened and ported as well as the combustion chambers tidied up and volumes matched.
I have checked all the valve stems and guides and are all in tolerance and valve seats are good also
I've been checking out burtons site and I'm planning on getting a cam kit it fit with the new head once it's all done.
I use the car on track days and for weekend touring so need a cam that will still be drivable at low end
At the moment the fr 32 and fr 33 cams seems to be the suggested ones cam any one guide me to witch one would be better?
The 32 power band is between 2500-7000 rpm
The 33 power band is between 3000-7500 rpm
A recent rolling road shows the current engin ( not with new head on) only produces power up to 5500 rpm but this may change after the above
improvements are made ??
Any help would be great
Cheers ryan
The key to it is how much head work you have had done. If it is only minimal then the FR33 won't release it's potential and the FR32 will be
a better way forward. If you have had the 'full works' on the head then the FR32 won't extract the best from the work that you have
done and the FR33 is the best choice.
It's difficult to tell from your description of the work but I think I would go for the FR33. I have used this one and I got a perfectly
acceptable tick over and good power up to and over 7000 rpm in bursts. I used the 205 block injection engine as a start - it has the best conrods and
and biggest valves as standard.
quote:
Originally posted by mookaloid
The key to it is how much head work you have had done. If it is only minimal then the FR33 won't release it's potential and the FR32 will be a better way forward. If you have had the 'full works' on the head then the FR32 won't extract the best from the work that you have done and the FR33 is the best choice.
It's difficult to tell from your description of the work but I think I would go for the FR33. I have used this one and I got a perfectly acceptable tick over and good power up to and over 7000 rpm in bursts. I used the 205 block injection engine as a start - it has the best conrods and and biggest valves as standard.
Just to add a bit...
The injection engine has better rods and inlet port short side turn
Ports do not need enlarging bigger inlets will help
Compression needs to be 10. To 1 or above but 10.5 is the cast piston limit
Rods are good to 7000 with the odd 7500
You need to measure piston to deck height & combustion chamber size, you can only work out compression accurately with these measurements.
There are head gaskets with different thickness which can be used to good effect
The Pinto likes compression
The pistons don't
The FR32 & 33 like to rev
The rods don't
Most Pinto cams have a little more lift and lots of duration, the Pinto likes lots of lift and less duration
The FR34 does well here but is all done by 6500
I had a 2.1 with standard injection head, FR32 and bike carbs it made 130bhp and 135ft/ibs with little tuning
IMHO FR32 for a better all round drive and would not only tick over well but pull hard low down and go on untill my nerves ( and ears) gave out.
I am in the process of building a 2.1 with Cossy rods & V6 pistons, (should have gone forged) I will use an RL31 cam and 10.7 to 1, when I tried
this combo the engine felt weaker than the FR32 to 3500 then took off
quote:
Originally posted by snapper
Just to add a bit...
The injection engine has better rods and inlet port short side turn
Ports do not need enlarging bigger inlets will help
Compression needs to be 10. To 1 or above but 10.5 is the cast piston limit
Rods are good to 7000 with the odd 7500
You need to measure piston to deck height & combustion chamber size, you can only work out compression accurately with these measurements.
There are head gaskets with different thickness which can be used to good effect
The Pinto likes compression
The pistons don't
The FR32 & 33 like to rev
The rods don't
Most Pinto cams have a little more lift and lots of duration, the Pinto likes lots of lift and less duration
The FR34 does well here but is all done by 6500
I had a 2.1 with standard injection head, FR32 and bike carbs it made 130bhp and 135ft/ibs with little tuning
IMHO FR32 for a better all round drive and would not only tick over well but pull hard low down and go on untill my nerves ( and ears) gave out.
I am in the process of building a 2.1 with Cossy rods & V6 pistons, (should have gone forged) I will use an RL31 cam and 10.7 to 1, when I tried this combo the engine felt weaker than the FR32 to 3500 then took off
If you have a little more cash to spend, a good thing to do is lighten the flywheel and have the whole bottom end dynamically balanced. This will make it accelerate better (less inertia) and run smoother particularly at higher revs.
quote:
Originally posted by mookaloid
If you have a little more cash to spend, a good thing to do is lighten the flywheel and have the whole bottom end dynamically balanced. This will make it accelerate better (less inertia) and run smoother particularly at higher revs.
I'm looking for a similar result with mine and I ended up picking a piper 285 cam (2200 -7000rpm, 270° duration, 11.81mm/0.465" lift)
I've got a 205 block rebored to 93mm (=2090cc), running with cossie rods & crank, forged pistons, steel flywheel all ballanced together
I've got ZX9R 'CVR' carbs, megajolt and dax's std. 4-1 exhaust.
I've left the head almost standard for now (just bronze guides, 3 angle valve seats and a bit of a skim) will do some porting later if I keep the
head (may go for a NA cossie instead)
the engine builder that did the maching for me skimmed the head to give me around 11.0 - 11.5 CR not sure what he took off, but he builds pinto's
all the time and knows what he's doing (I'll measure the combustion chambers to work it out exactly at some point)
my pistons are flush with the top of the block so there isn't much room for things to go worng
I'll find out if its the right choice once I actully finish building the car....
[Edited on 6/9/2012 by mcerd1]
quote:
Originally posted by ryanill
quote:
Originally posted by mookaloid
If you have a little more cash to spend, a good thing to do is lighten the flywheel and have the whole bottom end dynamically balanced. This will make it accelerate better (less inertia) and run smoother particularly at higher revs.
Right oh
The fly wheel is already lightened and balanced
I asked the guy to make it as light as possible and still be safe. Ended up getting it to about 5 kg. how much dose the engine balancing generally cost ?
I have all the gaskets ready for the rebuild but not a head gasket yet as I was aware there are different thickneses that with alter compression ratio
. So that with be sorted once it all goes back together . I'll defiantly look into balancing the bottom end yes
I'm sure the work will yield improvements in power, I'm just interested to see how much I will see and if you can get noticeable results
with small budget and a bit of work or if you want to see results do you have to pay for the head work to be done professionally .
Yes please post back once the car is finished will be interesting to compare results
quote:
Originally posted by ryanill
I'm sure the work will yield improvements in power, I'm just interested to see how much I will see and if you can get noticeable results with small budget and a bit of work or if you want to see results do you have to pay for the head work to be done professionally
quote:
Originally posted by snapper
Just to add a bit...
The injection engine has better rods and inlet port short side turn
Ports do not need enlarging bigger inlets will help
Compression needs to be 10. To 1 or above but 10.5 is the cast piston limit
Rods are good to 7000 with the odd 7500
You need to measure piston to deck height & combustion chamber size, you can only work out compression accurately with these measurements.
There are head gaskets with different thickness which can be used to good effect
The Pinto likes compression
The pistons don't
The FR32 & 33 like to rev
The rods don't
Most Pinto cams have a little more lift and lots of duration, the Pinto likes lots of lift and less duration
The FR34 does well here but is all done by 6500
I had a 2.1 with standard injection head, FR32 and bike carbs it made 130bhp and 135ft/ibs with little tuning
IMHO FR32 for a better all round drive and would not only tick over well but pull hard low down and go on untill my nerves ( and ears) gave out.
I am in the process of building a 2.1 with Cossy rods & V6 pistons, (should have gone forged) I will use an RL31 cam and 10.7 to 1, when I tried this combo the engine felt weaker than the FR32 to 3500 then took off
No I don't have a coppy of ether sadly but I do recal a friend mentioning a dave vizard book he had I'll have to ask him, if not fleabay it
will be for me
U2u sent . Thanks for offering the info i look forward to reading it.
Ryan
All the info i have ever read has said 10.5 max for Pinto cast pistons, i know some get away with 10.7 and even heard of 11 to 1 (Turbosports forum)
but they will "life" the pistons as Pinto pistons and rings are big and the ring lands are known to give way.
Personally I don't want to be the one that does the research.
Des Hammil says 10.5 to 1
Vizard says 10.5 to 1
Mike Egan quoting a lot of respected US builders says cast pistons are worthless
I could be running close to 8,000 with Cossy rods but will red line at 7500 due to the 2.8 V6 pistons.
If you have valid info on running over 10.5 on cast pistons i would be happy to add that to my bank of Pinto knowledge.
ryanill,
The Des Hammil book is an easier read but if you do nothing else on your standardPinto head, smooth off the inlet port short side turn just below the
valve seat.
If you compare the standard Pinto and the Injection head its this area above all that makes the difference and gives the injection engine 5 to 10 bhp
more.
quote:
Originally posted by snapper
All the info i have ever read has said 10.5 max for Pinto cast pistons, i know some get away with 10.7 and even heard of 11 to 1 (Turbosports forum) but they will "life" the pistons as Pinto pistons and rings are big and the ring lands are known to give way.
Personally I don't want to be the one that does the research.
Des Hammil says 10.5 to 1
Vizard says 10.5 to 1
Mike Egan quoting a lot of respected US builders says cast pistons are worthless
I could be running close to 8,000 with Cossy rods but will red line at 7500 due to the 2.8 V6 pistons.
If you have valid info on running over 10.5 on cast pistons i would be happy to add that to my bank of Pinto knowledge.
quote:
Originally posted by snapper
ryanill,
The Des Hammil book is an easier read but if you do nothing else on your standardPinto head, smooth off the inlet port short side turn just below the valve seat.
If you compare the standard Pinto and the Injection head its this area above all that makes the difference and gives the injection engine 5 to 10 bhp more.
quote:
Originally posted by snapper
All the info i have ever read has said 10.5 max for Pinto cast pistons, i know some get away with 10.7 and even heard of 11 to 1 (Turbosports forum) but they will "life" the pistons as Pinto pistons and rings are big and the ring lands are known to give way.
Personally I don't want to be the one that does the research.
Des Hammil says 10.5 to 1
Vizard says 10.5 to 1
Mike Egan quoting a lot of respected US builders says cast pistons are worthless
I could be running close to 8,000 with Cossy rods but will red line at 7500 due to the 2.8 V6 pistons.
If you have valid info on running over 10.5 on cast pistons i would be happy to add that to my bank of Pinto knowledge.
Interesting points you make, I think the issues is getting it set up properly with pump gas and bike carbs, or any carb.
I would feel better if I had injection set up properly and have also heard of reduced advance to negate detonation, perhaps loosing some bhp.
I take your point though and seeing your forum name understand where you are coming from.
I have a conundrum, the head I have gives 11.2 to 1 on a 93mm bore, the cam needs at least 10.5 to 1 and I have been working on the premise that 10.5
is my max for the pistons, although when push comes to shove ill be closer to 10.7 but 11+ you sure??
quote:
Originally posted by snapper
Interesting points you make, I think the issues is getting it set up properly with pump gas and bike carbs, or any carb.
I would feel better if I had injection set up properly and have also heard of reduced advance to negate detonation, perhaps loosing some bhp.
I take your point though and seeing your forum name understand where you are coming from.
I have a conundrum, the head I have gives 11.2 to 1 on a 93mm bore, the cam needs at least 10.5 to 1 and I have been working on the premise that 10.5 is my max for the pistons, although when push comes to shove ill be closer to 10.7 but 11+ you sure??
Don't want to nick the thread, but I'm running a well built head, large inlet standard exhaust, very nice porting, V6 pistons on Cosworth
rods, RL31 cam, bike carbs and Megajolt with MAP.
Engine has ARP everywhere, balanced inc light steel fly and clutch cover
Crank scraper, modified Cossy pickup with spraybar and high pressure pinto oil pump with cosworth oil pump top plate
Next purchase is an AFR meter and lambda
Thanks for the info I will build to the conservative 10.6/7 and limit the all in to 34 for starters
Always interesting technical conversations on this forum and I learn every day
Will keep you all posted on my build
quote:the same as me
Originally posted by snapper
Engine has ARP everywhere, balanced inc light steel fly and clutch cover
Crank scraper, modified Cossy pickup with spraybar and high pressure pinto oil pump with cosworth oil pump top plate
A couple of things that I have picked up over the years.
Firstly, it is VERY easy to over-cam an engine. The figures look good on paper, but remember what type of driving the car will be used for. The
compromises lower down the rev range can be hard to live with
Secondly, the dynamic CR is affected by the cam? so a wilder cam will require more CR. I expect many of teh compression issues are, as pinted out
earlier, to do with incorrect ignition and/or fuelling. I get really worried when people talk about a nicely built engine, then ask if the carbs
should just have the jets drilled out to XXXmm. That is no way to treat an engine, mapping needs to be far more accurate when pushing the engine.
All just observations (and some hard-won experience)
quote:
Originally posted by snapper
Don't want to nick the thread, but I'm running a well built head, large inlet standard exhaust, very nice porting, V6 pistons on Cosworth rods, RL31 cam, bike carbs and Megajolt with MAP.
Engine has ARP everywhere, balanced inc light steel fly and clutch cover
Crank scraper, modified Cossy pickup with spraybar and high pressure pinto oil pump with cosworth oil pump top plate
Next purchase is an AFR meter and lambda
Thanks for the info I will build to the conservative 10.6/7 and limit the all in to 34 for starters
Always interesting technical conversations on this forum and I learn every day
Will keep you all posted on my build
I have a set of R1 carbs and a TPS megajolt ready to swap out the Mikunies and MAP jolt