Martin’s PRV bone yard…

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Martin’s PRV bone yard…

Postby MFaulks » Sun Feb 26, 2012 2:06 am

Well various things are piling up :-) .. so I thought I would share some musings and the odd bit of useful info… you never know..

So the motor for my w/shop buddies blue GTA (F50) has started coming together. The car is over in this thread:
http://www.renaultalpineownersclub.com/ ... php?t=4899

As time has gone on, I have been revising my original decisions and so the process just keeps rolling as other things (project engines) come in-between. But the final configuration and hardware has been fixed as I have beg-borrowed- and stolen for other projects, and vice-versa. So I believe I now have a turbo of sufficient size for it, and hence cam choices came back up again, reversion issues, porting, lift, valve spring rates to match the rpm range etc… much fun, but cams are now in grind, springs selected and the heads machined to take them, and presently doing some final flow checks.. So hopefully, and committing myself here may get something moving in the near future on this one.

Here’s some pics of the 2.5ltr bottom end assembly with some mods in ring selection, wrist pin to reduce reciprocating mass, lower comp OE pistons, bearing cap checks before align-hone etc.. fun fun..

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Some head mods for a different valve spring setup, and new lift cams bringing everything much closer together…

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I got asked about 2.5ltr turbo cam profiles the other day, and having just done a new atmo profile for a 3ltr, thought I would go back and look at it again. But for those of you looking for an upgrade on the standard head, then don’t go too exotic as the flow figures below (taken at 10”) will show you that the OE hardware won’t support a substantial hike in volumetric efficiency, and hence power limited… Lee, RATS does a nice upgrade package cam and followers, and this would be as far as I would go. Will’s car achieved 275hp (2.5ltr OE engine, cam and follower upgrade, T3 hybrid, Renix remap), and had a bit more in the pot because it was starting to lean out (injector size limited, so cut run), but I think probably 285hp would have been a realistic top end if the fuelling had been closer to optimal. To go further it would need improved breathing…

Can read up on that one here for those that have not seen it:
http://www.renaultalpineownersclub.com/ ... 2&start=15
http://www.renaultalpineownersclub.com/ ... php?t=4840
http://www.renaultalpineownersclub.com/ ... php?t=5493

The interesting thing is the PSA / Douvrin engineers did do their home work on this design, and must have had quite strict guide lines as to the target performance (cost / performance I guess) from the project team. The GTA turbo and GTA atmo (n/a) share the same head, only difference being revised valves and different cam. The atmo has the same arrangement as the R30. The 44mm inlet valve has a throat of 37.45mm or exactly 0.85% of the valve diameter (note well), and well coordinated to work with the 30 deg seat. Why did they do this, well modest performance requirements and low lift cams.. I guess the modest performance, only necessitated the low lift cam arrangement giving longevity, and the use of 30 deg seat being used to gain back low lift flow given chosen cam arrangement. Note that in subsequent revisions of the engine, higher lift cams were utilised with valves on a more common 45 deg seat, and the later Volvo engines were blessed with the highest lift of the production engines. However, the down side of the OE arrangement is reduced flow at higher lift when you are looking for bigger performance upgrade, and the greater propensity to reversion i.e. charge contamination during valve open overlap. The only way forward with that aspect is valve, and valve seat angle revisions.

Anyway, to the inlet flow of the OE 2.5ltr head taken at 10” depression on a Superflow 120… and before anybody asks, yes these figures are corrected :-)

Lift from 50 thou, and then 50 thou increments up. OE cam lifts the inlet valve to 280 thou, give or take a bit… and all results cfm

44mm valve, 37.5mm throat
17.1, 38.9, 58.2, 73.7, 85.6, 91, 93 at 350 lift, and 96 cfm at 400 lift.

These figures were taken with the best flowing version of the inlet valve, there are options.. and there is about 3% difference between them, so free HP for no other change.

Given the throat and stem, calculation gives a theoretical flow of 13.73 cfm / mm lift. If you do the math you will see the designers did a pretty good job up to the OE cam lift, beyond that was outside their scope.

Looking at this and doing what most would classify as a stage I tune, resulted in the following (somewhat biased to higher lift):

15.5, 32.7, 49, 65.3, 81, 93.4, 100 at 350 lift, and 105.5 at 400 lift.

Hence, no net gains unless you lift past the OE valve lift, and then life starts looking good. To put this in perspective, the cam Lee packages up will get you just over 9% gain on flow.

So then I thought within the limits of repeatability what can be achieved and these are my figures a few days later and much playing:

18.5, 37.4, 55, 72.2, 89, 104, 114 at 350 lift, and 119 at 400 lift.

To take advantage of this a nice 9mm lift cam within the limits of the OE spring would work very nicely, and profit 22.5% improvement in flow without a significant degradation in port velocity… now there’s a thought :-) Anybody still reading? So here’s a pic… I know you all like ‘em…

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... A diamond is only a piece of coal that did well under pressure... PRV afflicted, may be I need to squeeze harder!!!!

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cool

Postby Miles » Sun Feb 26, 2012 9:58 am

Cool, good info.[/i]
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Postby MFaulks » Sun Feb 26, 2012 10:46 am

... and why bone yard?... :lol:

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.. Volvo block there, better sump arrangement but doesn't fit in the GTA chassis.. Pity really...

A whole pile of useless info in there... :roll:
... A diamond is only a piece of coal that did well under pressure... PRV afflicted, may be I need to squeeze harder!!!!

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Postby clee » Mon Feb 27, 2012 8:15 pm

You obviously didn't get the Ebay email either :lol:
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Postby clee » Mon Feb 27, 2012 8:17 pm

Image


What that film with Jodie Foster ??? Space portal type thingy .....
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Postby PaulC1959 » Mon Feb 27, 2012 8:22 pm

clee wrote:You obviously didn't get the Ebay email either :lol:


:lol: :lol: :lol:
3 Blue cars, 1 Black car, No Burgandy car anymore! :o

Quick! Somebody hide my cheque book, this many cars is getting serious ;o)
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Postby MFaulks » Mon Feb 27, 2012 11:40 pm

clee wrote:What that film with Jodie Foster ??? Space portal type thingy .....


:lol: ... come on then, what's the name got me intrigued, sounds like a must watch? :wink: 8)

…a set of 93mm liners came out of there, well 4 or 5 wasn’t it :wink:

I had a job like that once, yesterdays junk would become today's good stuff :lol: :lol:
... A diamond is only a piece of coal that did well under pressure... PRV afflicted, may be I need to squeeze harder!!!!

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Postby MFaulks » Tue Feb 28, 2012 12:27 am

... that, and the pile of heads on my back seat...

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cheapo gaskets, don't use 'em...

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... A diamond is only a piece of coal that did well under pressure... PRV afflicted, may be I need to squeeze harder!!!!

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Postby jonc » Tue Feb 28, 2012 4:51 pm

MFaulks wrote:
clee wrote:What that film with Jodie Foster ??? Space portal type thingy .....


:lol: ... come on then, what's the name got me intrigued, sounds like a must watch? :wink: 8)


'Contact'. Worth a watch.
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Postby clee » Tue Feb 28, 2012 5:31 pm

:wink:

Yep ,Carl Sagen novel so a bit :?

http://www.youtube.com/watch?v=hUw13iIrKN0
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Postby PaulC1959 » Tue Feb 28, 2012 7:18 pm

jonc wrote:
MFaulks wrote:
clee wrote:What that film with Jodie Foster ??? Space portal type thingy .....


:lol: ... come on then, what's the name got me intrigued, sounds like a must watch? :wink: 8)


'Contact'. Worth a watch.


Yep that's the one, kept me quite for a while. :lol:
3 Blue cars, 1 Black car, No Burgandy car anymore! :o

Quick! Somebody hide my cheque book, this many cars is getting serious ;o)
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Postby MFaulks » Wed Mar 28, 2012 11:09 am

Quick update, well more a question for the Alpine technos and others in the know out there… does anyone know if the Bi-turbo Safrane and the A610 engine had the same camshafts? Any anecdotal info would be good… :idea:

I know they both share the same core head casting number, but don’t know if the machining detail is different. The reason is the 12V 3ltr even-fire of the Laguna etc also shares the same head casting (so share the head core detail – porting, chamber etc) as the A610 and Safrane, however, I was about to test and digitise the A610 cam profile but the cam wouldn’t fit my 3ltr bench test head. The cam journal closest to the sprocket is larger in diameter… interesting, so you couldn’t retro fit A610 cams in an otherwise OE 3ltr 12V head... I guess to try and keep the parts exclusive to that build, and hence my question about the Bi-turbo units as well? :?

Hence, a little rough turning and the lobes were soon digitised for my records :wink:

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As it turns out the cam isn’t that special, and has some similarities to the old turbo Buick profiles :arrow:

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As another little side investigation, I have been testing various GTA / 610 clutch pressure plates with some interesting results…

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... A diamond is only a piece of coal that did well under pressure... PRV afflicted, may be I need to squeeze harder!!!!

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Postby jon_viola » Wed Mar 28, 2012 6:04 pm

As another little side investigation, I have been testing various GTA / 610 clutch pressure plates with some interesting results…

Image[/quote]

So what news?! Do tell....
1989 GTA Turbo
2003 Mercedes E320 CDI Estate- A.K.A Badke Bus

www.badkequartet.co.uk
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Postby MFaulks » Tue Apr 03, 2012 10:24 am

As I mentioned in John's great thread, Eddie's TB conversion manifolds; well here's a set (owners Jenvey TBs) going on a 3ltr 12V efi conversion (Fenix 3A) being fitted into a Nobel P4... I have to say the car looks lovely, I'll get some pics.

Engine spec is OE except a 280 deg cam, TBs with efi conversion, Nobel headers and some other touches... I just want to hear it, never mind how it goes :)

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Postby MFaulks » Sun Apr 15, 2012 9:35 pm

jon_viola wrote:As another little side investigation, I have been testing various GTA / 610 clutch pressure plates with some interesting results…

So what news?! Do tell....


Answer: 1/3 extra pressure on the A610 backing plate... worth the money IMO
... A diamond is only a piece of coal that did well under pressure... PRV afflicted, may be I need to squeeze harder!!!!

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