Longer conrods to Cosworth YB engine
 

What kind of benefits is there to change longer conrods to cosworth engine? I'm going to buy new pistons and might change the conrods at the same time. Does longer conrod affect to the CR to be used? I mean that can the same ignition advance be used with longer conrod compared to the standard cosworth conrods?

How much longer are you thinking?

5mm or 10mm both are available and pistons to go with them. I know that the 5mm longer rods with arp bolts are about 300pounds new.

Up if someone else is interested. I'm not going to build high revving engine, since I want as much torque low down as possible and of course still power on the revs.

BTT

Those rods are intended for High CR N/A use

I think you will struggle to find pistons to work with them to keep the CR low enough to use in a turbo engine that you want to be making lots of torque low down (ie 8:1 or less)

https://passionford.com/
8mm longer rods ;) if you are thinking of changing rods then longer is better,
I would run the same comp ratio as sorter rods as there is not much to be gained from that, Only rod angle and reduced loading on bores.
If the link doesnt work search for Mad ade dyno results.

Mark

Come on Mark sort the link out lol

mike

I cant work it out :cry: it dont work :cry: You do it :DD:

Mark

https://passionford.com/forum/viewto...31368&start=38

10th post down.

Thats why you use Autronics it is simple to use press 75 then enter please :cry: :cry: :cry: :cry: no need for links :cry: :cry:


Mike

The pistons are being made by Ross or CP probably, haven't decided yet which one to use.

Okay, thanks for the reply. I'll have to think which way to go. The new longer rods wouldn't be that much expensive and I can get some money from the old ones, so why not change to longer rods if they are better. My engine isn't going to be that massive, hopefully something like 450hp/600Nm and 2bar of boost or atleast those are the numbers I'm aiming for.

I only use CP so you know which ones I recomend ;)

Mark

Okay, I have now ordered 5mm longer rods and custom made CP pistons to suit them with 8:1 compression ratio. I hopefully get them in next few feeks so I can get back to my engine build.

Does anyone on here have experiences from using longer rods (let's say those 5-8mm longer versions)? How does it affect performance? Does the powerband go further up, any gues how much? Does it give more power all over the powerband? Just interested in these since I have read somewhere that it would make these things, but I have no idea how it works in reality.

The WRC engines in retsricted format, gain 15bhp by using longer rods, and an extra 500rpm rev range. I don't know anyone else that has done a direct back to back comparison....

The longer the rods, the less torque you get, but more bhp. However, 5mm is not going to make much difference either way. I would have done what Mark suggested and bought 8mm longer rods with the correct CP pistons, and I personally think that your c/r is too high and will require huge amounts of retard on the top line whilst flat out.

Okay, thanks for your info. Like I said, I would have kept the standard rods, but I got those longer h-beam rods that cheap so I think it was a good choice and those 8-10mm long rods would have cost me 2-3 times more. So I think my option was best value for my money. I have had no problems yet with my standard compression ratio with 24psi and flat out runs. The old setup had only ~400bhp/~390lbft but will see how it works with the new engine. Nice to see new results since I know have 4-egt sensors in the exhaust. My old engine had about 15degrees advance at 24psi and 6500rpm but is that what you mean by saying that it is retarded too much?

That comp ratio will be fine at your aimed HP and boost.

Mark

carwise has got a bottom end on ebay now with pistons to suit longer rods.......

http://cgi.ebay.co.uk/ws/eBayISAPI.d...6372&rd=1&rd=1

15 deg is retarded for flat out running ;)
:cry:


really depends on engine mate :top:

I finally had time to go to the rollers yesterday. I'm well pleased with the results. Even tough we could have made some more adjustments, but I tought it would not be necesary. I think we could have used more ignition from 6000rpm upwards and the fueling was bit rich, something like AFR11,0. 2deg advacing the ignition gave about 5kW more power at ~6000rpm. The boost is peaking 1.7bar and then slowly drops to 1.5bar at rev limiter. I'll need to do some minor modifications to it so it holds the boost better.
Exhaust temperatures were measured ~2cm from the head at the exhaust manifold, they showed no more than 740-760deg in each 4 runners. I think that they could have been more, so the fueling was maybe too rich/safe. Inlet temperature showed 30deg before the pull and 55after the pull. Newer seen more than 40-45deg on the road although.

Here's the engine spec if someone is interested:
standard 4wd cams (timed inlet 1mm open TDC and exhaust 0.8mm),
ported head with race valve seats,
5mm longer conrods with cp-pistons from TG-racing sweden,
comp ratio around standard 8:1,
3" mongoose exhaust with 3" race catalysator,
rs500 size intercooler,
4wd inlet plenum with modified elbow
Finnish aftermarket ecu, Tatech

http://kotisivu.dnainternet.net/jtuomol6/esco/dyno.jpg

..

Congrats :top:. Is 450bhp what you were hoping for? :)

Yes it was. I was actually after wider powerband and the extra 34kW's were just extra :) Here's the old graph for comparison. Basically same engine, but just tweaked a bit.

http://kotisivu.dnainternet.net/jtuo...dyno_vanha.jpg

What turbo you running? (or did i not spot that bit)

Holset HX35 with 54/60mm wheels. It is usually used in some 5.9L cummins diesel engine.

nice..

is that 334kw at the flywheel or at the wheels?

It's flywheel figure.