Kotwica Eng in AR stroker cranks etc

[MFaulks]

Hi, did a quick board search and not seen anybody mention them, they do some long stroke cranks, rods etc for the 5GT:

http://www.kotwica-engineering.com.ar/ingles/kits/kit_renault5gt.html

I found them looking for some Fiat SOHC stuff, but not known anybody that has used these guys, looks good stuff though, any experience from here?

Thanks,
Martin

[markey b]

KRN013 = a 1.7 c1j?!?!

[Os8472]

interesting, anybody ever tried these bits

Wonder much of difference they would make without reducing strength

[MFaulks]

These are from billets, go up to the main site, so there should be no real strength issues - sure appreciate about the crank pin / web over-lap, but don't think these dimensions are going to be extreme, and likely using superior materials. I've found another Argentinean supplier doing similar..
http://www.ercolicompeticion.com.ar/

Any chance of a group buy or discount, I could then order up a crank to convert my Fiat X19 1.5 SOHC screamer to a 1.7 with discount :-)))

Apparently a lot of the Fiat community (France Germany etc), are using the kotwica cranks, and Oliver rods... cheaper than the EU stuff...

I'm definitely in if others are interested and try and get a group buy, obviously I'm after a Fiat crank though ;)

[michael tierney]

if u went for the 1587cc what would your compression be?you'd have to be able to program the retard!!:(

[Big Jim]

81mm bore, is there any liner left :confused: The CR would be the last of your worries.

If you were going to the trouble (and expense!) of fitting a stroker crank, surely you'd go a bit more exotic on the management front too.

[Os8472]

These are from billets, go up to the main site, so there should be no real strength issues - sure appreciate about the crank pin / web over-lap, but don't think these dimensions are going to be extreme, and likely using superior materials. I've found another Argentinean supplier doing similar..
http://www.ercolicompeticion.com.ar/

Any chance of a group buy or discount, I could then order up a crank to convert my Fiat X19 1.5 SOHC screamer to a 1.7 with discount :-)))

Apparently a lot of the Fiat community (France Germany etc), are using the kotwica cranks, and Oliver rods... cheaper than the EU stuff...

I'm definitely in if others are interested and try and get a group buy, obviously I'm after a Fiat crank though ;)


I was meaning about having a larger bore piston there for reducing the wall thickness of the liners

[Woznaldo]

You'd think they would do uprated liners to match too?

I'm with you Big Jim on going more exotic on the induction side, after all the std carb is still going to be a restriction.

Once again this will come back to the gearbox being able to handle all the extra torque.

I would say, if you're going to go done this route, then the best option would be a high CR, low boost, running EFI with the appropriate throttle body size.:coffee:

[Lewis]

Renault didn't go past 77mm bore and 82mm stroke in the 5 Maxi, I wouldn't push past that on the bore things start getting to thin. As for crank I think 84mm cranks are available which give you 1565cc. The best option if you want more cc's and aren't limited by competition rules and regulations would be to ditch the c series engines altogether.

[Andrew Cooke]

I think at 81mm you'd need to machine a single liner with 4 bores rather than 4 individual liners.

[Big Jim]

I've been having similar thoughts to that, just a bit put off by the machining involved to make it fit.

Another thought I had was offsetting or staggering the bores. I know it messes up relative timings a bit with the cylinders being des-axe(is that how you spell it?) in opposite directions, but it would give some more room. Do you know if the smaller capacity engines use the same size liner spigot bore?

[Andrew Cooke]

I've been having similar thoughts to that, just a bit put off by the machining involved to make it fit.

Another thought I had was offsetting or staggering the bores. I know it messes up relative timings a bit with the cylinders being des-axe(is that how you spell it?) in opposite directions, but it would give some more room. Do you know if the smaller capacity engines use the same size liner spigot bore?

Some of the Honda tuners have made single inserts. I'm sure someone will be able to find a link.

With offset boring I don't suppose a mm here or there would cause a huge problem geometrically, that could presumably be fixed with conrods if it was large. However when I looked at that a few years back there didn't seen to be a geat deal of space in the block to move the outer bores outwards.

I don't know about the liner spigot bore on smaller engines, I'll guess that they're the same. From memory you need to bore them out to fit the 78mm liners, I've only seen the 80mm stuff advertised as N/A, I imagine that's due to the cylinder wall thickness.

With the head being so pisspoor on the GTT I'm not sure how much of an advantage the larger engine would be.

[MFaulks]

Andy, I’m sure this has probably been covered else where, so excuse my ignorance as I don’t know the heads other than a few photos I've seen on here, but what is so poor about them? Where are the restrictions? Just out of interest.

I know it’s non-cross flow and 2v, but my 1500 SOHC non-cross flow 2v Fiat n/a motor pulls 160 bhp @ flywheel and roughly 140ft/lbs torque on side draught 40s, which isn’t bad. Can get it up higher, and currently working on that, but would imagine with forced induction if the heat is taken care, it would be quite a scream; surely the 5GTT head isn’t totally crippled? I'm only asking the question out of interest, don’t get me wrong. Is there space to down draught the inlet ports, mill down and tube to the back of the inlet valve? ... sorry jumping ahead ;) I’m not saying this is the most sensible thing to do, and definitely not the most economical, just a question….but some people do it though… :)

[Andrew Cooke]

Andy, I’m sure this has probably been covered else where, so excuse my ignorance as I don’t know the heads other than a few photos I've seen on here, but what is so poor about them? Where are the restrictions? Just out of interest.

I know it’s non-cross flow and 2v, but my 1500 SOHC non-cross flow 2v Fiat n/a motor pulls 160 bhp @ flywheel and roughly 140ft/lbs torque on side draught 40s, which isn’t bad. Can get it up higher, and currently working on that, but would imagine with forced induction if the heat is taken care, it would be quite a scream; surely the 5GTT head isn’t totally crippled? I'm only asking the question out of interest, don’t get me wrong. Is there space to down draught the inlet ports, mill down and tube to the back of the inlet valve? ... sorry jumping ahead ;) I’m not saying this is the most sensible thing to do, and definitely not the most economical, just a question….but some people do it though… :)

34mm inlet valve...

[MFaulks]

... and there isn't room to get larger in there? What size is the bore?
I'm guessing now this is long stroke and you have restricted bore area to work in? The exhaust valve is quite big though isn't in relation to bore area? What size is it?

Could you change over to 7mm or 6mm valve stems and offset the guide centre? That's what I did on my Fiat, 7mm stem and 1mm offset. 40mm inlet and 35 exhaust. Now doing a head 6mm stems, more offset and 41mm inlet ;)

[Big Jim]

I had a bit of a chat with someone a while back about what constituted the ultimate C1j head. All that you have just described is do-able, it's just a case of finding someone who wants to spend enough money to make it viable.

[MFaulks]

umm.. well I'm quite curious now, does anyone have a scrap head ideally with rockers and valves that are willing to donate for a trial? Kinda a one-way trip though, as it will be all mashed around, but if anybody else is curious chip in.

Jim, I'm prepare to prep one cylinder and flow bench test back-to-back against a standard chamber.. Curiosity killed the cat and all that... may be a couple of configurations and see. :) Are you interested in getting involved and do it as a bit of a Dave Walker special article… minus the auntie jokes? ;)

What is the benchmark 2v to make comparison, not considering 4v configs? Benchmark flow has got to be around 125 cfm/inch^2 at 28 inch water depression to be any kind of serious contender, and see how it compares. :coffee: Can then get the answer and see, kind academic but you never know. :)

[TrixNFlix]

Think ive got a scrap head in the loft. Its been skimmed to many times, but dont think it has the rocker gear, its deffo got the valves and springs. any use? regards andy

[Markey Mark (BD)]

Think ive got a scrap head in the loft. Its been skimmed to many times, but dont think it has the rocker gear, its deffo got the valves and springs. any use? regards andy

I got a rocker shaft here which i'm willing to lend.

I'm finding this thread really interesting, may bring out a few interesting ideas and results.

[MFaulks]

yeah sounds ideal, couple of rockers and the posts will help, can look at the geometry, and valve stem length options that can be played with, but that's a different aspect really. Thanks :)

[TrixNFlix]

Give me an hour to get up in the loft and ill post some pics up of what ive got for you. regards andy

[modfather]

[quote=Markey Mark (BD);124246]I got a rocker shaft here which i'm willing to lend.

if this any good i got a rocker shaft here that you can have if you want to pay for posting:)

[Andrew Cooke]

benchmark has to be the gordini/alpine head std is ~37/34, mine is 40/36. you can go bigger but cylinder shrouding on the 76mm bore is a problem.

[MFaulks]

ok, thanks for the offers on parts, loans or otherwise, much appreciated. Postage, sure no problem obviously want to keep incidental outlays down, as and costs better go into mods, seats etc... so if pickup can be arranged and I'm passing &/or meet, then happy to do that as well. Suggest drop me a PM to save clutter on here, and I’ll get back to you. What’s the diameter of the rocker shaft by the way?

Thanks Andrew, are you happy to share your flow figures against lift inlet / exhaust, or pm if rather not list? This will really help. Do you know what your throat and major port dimensions are? Yes I remember you mentioning the shrouding on the GTA thread. Out of interest when you flow bench tested your head did you try just offsetting the head on the dummy cylinder to see the effect on flow and percentage loss?

[Andrew Cooke]

Thanks Andrew, are you happy to share your flow figures against lift inlet / exhaust, or pm if rather not list? This will really help. Do you know what your throat and major port dimensions are? Yes I remember you mentioning the shrouding on the GTA thread. Out of interest when you flow bench tested your head did you try just offsetting the head on the dummy cylinder to see the effect on flow and percentage loss?


This is for a bare head with a standard 38.7mm inlet valve, I only have the inlet, this is at 25"

0mm 0cfm
1mm 21.29cfm
2mm 39.88cfm
3mm 59.09cfm
4mm 80.29cfm
5mm 100.37cfm
6mm 118.42cfm
7mm 129.16cfm
8mm 140.36cfm
9mm 144.01cfm
10mm 147.56cfm

we didn't test it past 10mm, and ran out of time for any more testing.

[MFaulks]

Thanks Andrew.

Did you get the bare port flow figure, and port velocity profile, or average velocity by any chance?

[Andrew Cooke]

Thanks Andrew.

Did you get the bare port flow figure, and port velocity profile, or average velocity by any chance?

none of that, I can measure the port sizes when I get 5 mins.

[MFaulks]

Thanks for all the enthusiasm, and big thanks to Trix, Mod, and Markey for all the bits, will start pulling this together soon and hopefully have some fun or a big bang - either just as good.:D

PS.. what’s the going rate on Ally at the moment? Joke ;)