Max RPM on 2.5 stroker?

[as2nerka]

maybe some body can say what max rpm on 2.5 tall black with 95.5 crank and 155 rods ?

[JP]

Depends on how much money you are prepared to spend and how long you wish it to last.

If doing it as a budget build I personally would set peak at 7200 and continuous at 6500 if staying below 2bar boost. And would expect to see minor bore ovalling by 15-20,000miles. Major wear around 50-80,000miles depending hoe hard it has been driven.

If however budget is not an issue you could build one to be reliable for 10,000rpm with a seasonal strip down, replacing such things as big ends and rings that take the majority of the pounding.

[as2nerka]

my project 2.5 aat block 95.5 crank 155 rods 81.5 wiseco pistons 0.5mm oversize valves stronger valve springs titan retainers 7a camshafts furans intake and exhaust manifolds and much more, my frend said what it run about 7500 rpm and 2.0bar .
intresting becouse i use cbn gearbox from audi v8 and what max speed with this stroker and gearbox?

[Rocco]

Depends on how much money you are prepared to spend and how long you wish it to last.

If doing it as a budget build I personally would set peak at 7200 and continuous at 6500 if staying below 2bar boost. And would expect to see minor bore ovalling by 15-20,000miles. Major wear around 50-80,000miles depending hoe hard it has been driven.

If however budget is not an issue you could build one to be reliable for 10,000rpm with a seasonal strip down, replacing such things as big ends and rings that take the majority of the pounding.

this sounds crazy

PD: you have 666 posts... the day of the beast¡¡

[JP]

my project 2.5 aat block 95.5 crank 155 rods 81.5 wiseco pistons 0.5mm oversize valves stronger valve springs titan retainers 7a camshafts furans intake and exhaust manifolds and much more, my frend said what it run about 7500 rpm and 2.0bar .
intresting becouse i use cbn gearbox from audi v8 and what max speed with this stroker and gearbox?

Well the titanium retainers have shortened the lifespan for starters as they don't last as well as stock steel ones. However are required to relieve wear and tear on the rest of the valve train when upgrading springs, catch 22 like most things performance wise.

If running a 21mm wrist pin expect to see small end wear and eventually wear on the outer edges of the big ends if running those sort of boost pressures after 15,000miles or so if driven hard for most of its running life. I'd advice either a larger wrist pin or rifle drilling the rods like stock ones
which is my preferred choice.

RPM at the end of the day can easily be 8000rpm, however it will just not last as long.

As for top speed this is more down to the hp and weight of the car. For reference 1780kg, 800hp in am rs4 gets to around 210mph before running out of steam.

[JP]

@ Roco, lol well spotted

[Jamo]

No problems with stock redline with 2.5 deck, if it was a 2.2 deck and stroker crank then yeah 6500 redline

[caterpillar]

over 8k rpm; i will recoment drysump, and non hyd lifters...the bore stroke ratio are the same with 2,2 on a 2,5 with 155(158)conrods and dieselcrank.. nearly

[Jonnybravo]

I was going to ask how efficient the stock pump is at high rpm, I know the Vauxhall ones for example are crap as I expect most are if worked to that extent.

[JP]

It's not the efficiency of the pumps thats the issue. High rpm causes cavitation, which is basically air bubbles in the oil. A dry sump system with a remote tank removes these, a stock pump system does not and recirculates them compounding the issue. The thicker the oil the worse the problem, which is why high revving engines prefer thin oil.

The bearing failure on a stock pump comes from the air bubbles in the oil being unable to support the pressures involved. Much like a hydraulic brake system when it has air in it. As air compresses more than oil the more air you introduce into the oil the more likely your bearings make contact with the crank. A lot of the time people forget that overall flow of oil through the engine is more important than pressure at high rpm, resulting in old skool methods of running 10w50 oils on an engine that runs at a 90-100celsius constant with 110 peaks, instead of the more suited 5w40.

Back to the original question though stock engine could be revved to 8k but redline is set much lower from factory for reliability. In the same token you would only flash say 7200rpm for a momentary peak before gear change, you would not sit continuously at 7200 round an oval track at 2bar of boost.
I flash mine to 7650 on the strip but would not dream of sitting much over 6500rpm continuous especially at 2bar the EGT's would go through the roof.

[Jonnybravo]

By effiency I did mean issues with cavitation, poorly worded on my behalf as usual.

[JP]

LOL basically the issue of any gear driven pump