Cheers Graham I'm surprise that the 45mm webbers made over 200 hp with the 40mm chokes I'm going to stay with my 45s and not get 48s after your findings cheers mario
Miniliteman! I am well aware the larger capacity the engine is the lower maximum power will be produced if the engines are identical apart from the swept volume.
The cam manufacturers that are claiming maximum power at 8.500 Rpm are Piper, BP 320 and Kent with their GTS7, RC1 and GTS4 which is a copy of the old Holbay 4011FHL. (8.250 Rpm) maximum duration for the cams is 320. At this moment in time they have provided no reliable evidence to back up their claims.
If you trawl the internet there’s an article written by a retired UK Race engine builder by the name of David Baker. He went on to say that no mater how much porting on a conventional Pinto head with Group 2 valves, it would neither flow enough air or have enough air speed to keep producing power at well over 8.000 Rpm. He even went into the Laws of Physics to back up his claims, it was a very interesting read.
My second experience was speaking to another Race and Rally engine builder with over 50 years in the business building and Dynoing everything from BDA’s DFV’s Pintos and anything in between. He said the Pinto engine could not be made to produce enough Torque high enough up the Rev range to make high power figures at those sort of Rpm’s.
When I get the ex Memphis downdraught head that’s fitted to the engine in my Mk2 onto the Dyno I’ll report back what the peak power is, that’s fitted with a BF63. I am not expecting miracles, possibly max power around 7,800.
These are just a few of my experiences of working around the Pinto engine since the mid 1970’s.
If you look closely to the specs that cam manufacturers give you will see that they list a "powerband" . For instance 3500 - 8000 rpm. That second number does not mean that max power is / will be achieved at that rpm. It means that 80% or 90% of max power is achieved within that rpm-range. Max power usually is a couple of 100 rpm below that second number. But I guess you already know that as you say you expect max power of your engine with a BF63 cam (powerband 2800 - 8000) around 7800 rpm.
Don't know David Baker and what he has written and/or achieved. My statements are based on actual experiences with Pinto's on the dyno / rollingroad. Speaking to the engine builders of those engines (not me) and looking at the heads of these engines it is clear to me that if you want to "boldly go where no one ever went before" you need to think outside the box. And people who did are reluctant to share how they did it.
Hi Graham do you know the LSA of the p5 camshaft I got a email of Newman cams and ken said the LSA is around 110 can you confirm this Graham I would of thought it would be tighter cheers mario
It’s hard to believe a cam manufacturer would grind a Race cam on 110* lobe centres, that’s more Rally cam territory. It would have been interesting to find out what the P6 one was.
Interestingly I mocked a 4.75 Newman cam up in a head and equal lift was 145 thou which I though was a bit too much for a low duration cam. I didn’t bother checking the LSA as I didn’t want to use it in that head. There was big difference between different makes of followers too.
Valve timing figures that cam makers supply us with are meaningless unless the grinder supplies us with the elusive LSA angle and the head is then set up to that, not many do that.
The valve length has an effect on the LSA also I just set head up to get the right cam lift then the LSA will be very close cheers mario
Hello Mario.
The Lobe Separation Angle is a parameter of the camshaft, as is camlift and camtiming.
In a build engine you speak of valvetiming and valvelift. And yes these are dependant of valve length, valve play, follower geometry.
Usually as most aren't ground right and specified figures aren't achieveable and you have to settle for an average between the two
Well the p5 camshaft has 256 degs duration at .50 so it's a pretty aggressive camshaft if it only has 300 degs duration
It’s done by the valve length and the valve seat height. It can literally take days to get correct and very often tries your patience. You also need the correct tools which most hobby builders won’t have. But before all this you need to know off the cam grinder what the LSA should be.
i have just reassembled a head, before i stripped it it did have a burton cam which was way short on specified lift, it was also slightly damaged so i quickly tried a newman cam in its place, due to either base circle and or follower difference the newman was close to its specified figures, so i decided to go with that instead. having now stripped and rebuilt the head the intake lift is a few thou more than specified, its missing about 20 thou exhaust lift, but thats because whoever rebuilt it last fitted exhaust inserts that went too deep.
the way i saw it i had 3 options,
1 fit another set of seats - budget and time ruled that out
2 shorten the valves - didnt really want to as ive got to hack a lot off the end of an otherwise perfectly good valve
3 do nothing run with it- exactly what im going to do, its a fast road engine so i really dont think the loss of a bit of exhaust lift will make any real difference especially as i will swing the cam timing on the dyno anyway.
its easy to get too bogged down in numbers
This is my understanding - with a single cam the lobe centres are fixed to whatever the grinder has ground them to. Now, with a DOHC engine or multi cam engines, the sky's the limit and you can swing them around to suit application and desired characteristics ie. 100 - 104 deg Torquey NA or nice with a turbo through to 110 - 116 deg high rpm types. Advance or retard, most things are possible.
Maybe we're not making ourselves understood? With a single cam having fixed lobes, the LSA can be nothing but fixed! Playing with rocker ratio's, valve lengths etc. may alter valve lift (its obvious if you move from a 1.25 ratio that gives 10mm lift at valve, to a 1.5 ratio, it'll produce 12mm lift - that's simple maths / mechanics) what you cannot do is change the physical point on the cam that produces max lift (with whatever rockers or valves) between inlet and exhaust - that is the LSA! Only with a multi cam engine can variable LSA's be achieved as IN and EX are independent of each other! Adjusting valve timing with a single cam will always be a compromise - earlier lift / opening on inlet will correspondingly produce the same action on the exhaust.
If what you state is possible with a single cam, why do the manufacturers pour millions into designing, testing and producing dual cam engines having variable cam timing on one or both cams, if doing it with one cam would be cheaper (the best driver for manufacturers!) ???
you guys are almost arguing static V dymanic compression ratios here, same but different!
absolutely you cannot change a cams LSA without changing the cam, BUT anything which changes the valve geometry much have some effect of the LSA the engine actually sees,
whether there enough difference to actually make a difference i wouldn't like to say! i once spent a day on the rolling road playing with valve clearances and different types of spark plug, eventually we found 1 bhp!
Yet another one that doesn’t understand the geometry of the Pinto! Most people know by lengthening or shortening valves on a Pinto alters the maximum lift at the valve and by doing this you are then altering the rocker ratio from the heads std design. Also by changing the followers from different manufacturers can have a similar but small effect, by altering these you are then changing the cams LSA angle by small amounts. This is not something I have read in a book, it’s through days and days of measuring and altering things to find out through real experience. I was taught this some 35 years ago by Paul Gardner, one of the top engine builders in the North of England when I bought one of his cams, he too then must be wrong. There was also some reference to it in the Vizard Bible.
Last edited by Forest_rallying; 24-07-2022 at 07:23.
I give up !
i think Graham summed up above. cam lca is fixed but what the engine "sees " can change with valve train differences.
Italics are mine
Which is what i've been saying all along - one party won't accept it! See here - https://www.youtube.com/watch?v=ohDB5gbtaEQ LOL!
You’re a pretentious argumentative Bastard that comes across as some of a know all that always comes on this Forum to fall out with people, I am not the first and know doubt won’t be the last, whatever tuns you on.
I wonder how many Pinto engine builders have even taken the time to put a degree wheel on the cam pulley and check what the LSA is on each of the pair of cam lobes, not many by all accounts. I’ll trust the knowledge of a Race engine builder with over 50 years experience in the industry as being correct rather than some Internet Troll!
I'd rather be an 'pretentious, argumentative Bastard, Internet Troll 'know it all', who doesn't just accept what is said by others as fact and either query it or provides a correction if required. Personally I don't 'know' of anyone i've fallen out with - most conversations are topical, informative, good natured but I suppose some people may take offence just because they can. If I've ever said anything I thought was correct and later found to be incorrect, at least i'll apologise for the error unlike some who would just maintain they are right. Over & out!
Opinions are like Arse Holes, everyone has one and you appear to be the latter, as we say up North you can’t educate Pork. How many Race and Rally winning engine builders are there actually posting on this Forum? Certainly not you. Just accept Pal you are a Richard Head. As for fall outs with people on here I suggest to look through many of your last posts, over and out.
Lads relax and don't ruin the thread over opinions on valve timing, life is too short. Agree to disagree and let it go 👍
Sent from my SM-G980F using Tapatalk
a video on a few of the dyno steps that went into finishing this engine for now...
https://youtu.be/oWkpkXMCXAc
Nice to see the EFI coming out on top and when compared to the W48's - quite a bit of difference. Query (I know this wouldn't work long term) but have you ever tried the adjustable ram pipes on DCOE's?
PS - I like that cambelt damper arrangement above from Miniliteman - some of the belt flap in some of your dyno video's was amazing to see
no i haven't tried the adjustable trumpets on the webers, mechanically they might not work well as the weber trumpets actually clamp the aux vents in place.
the belt flap isnt lost on me, i might mock something up to see if i can find any difference on the dyno aside belt flap
Last edited by Graham; 06-11-2022 at 12:21.
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