So what are you Guys reving your 2.5L's to?
Ok I had to bring this post back from the dead, but for good reason. There has been some good information come about in the last 12 years. The 2.5s do like to rev and it has nothing to do with the rod ratio. This is my 2.5 stock bottom end, ported head, intake, header, and custom spec'd cam.. This thing loves the High rpms.. This is 6 psi / 11 psi / 15 psi
https://uploads.tapatalk-cdn.com/202...6275a57c52.jpg
Re: So what are you Guys reving your 2.5L's to?
Agreed, nothing to do with rod ratio but breathing.
I've found retarding stock cams helps move the power band to higher RPM.
Thanks
Randy
Re: So what are you Guys reving your 2.5L's to?
Thanks for the graph. That is some serious action for 15psi to say the least.
Re: So what are you Guys reving your 2.5L's to?
Quote:
Originally Posted by
cordes
Thanks for the graph. That is some serious action for 15psi to say the least.
Yessir, made 410 on 24 psi. Again that was with the stock bottom end. Have not had it back on the dyno with the built bottom end, but the increase in compression made a HUGE difference. I would guess and say 450+ on 24lbs.
Re: So what are you Guys reving your 2.5L's to?
Quote:
Originally Posted by
Loudexploder
Yessir, made 410 on 24 psi. Again that was with the stock bottom end. Have not had it back on the dyno with the built bottom end, but the increase in compression made a HUGE difference. I would guess and say 450+ on 24lbs.
What did you increase the compression to??
Re: So what are you Guys reving your 2.5L's to?
Quote:
Originally Posted by
chromguy
What did you increase the compression to??
I just bumped it to 9.3:1
I wanted to be around 10-10.5 but didnt want to wait on custom pistons
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Re: So what are you Guys reving your 2.5L's to?
Re: So what are you Guys reving your 2.5L's to?
Quote:
Originally Posted by
tryingbe
What fuel did you use?
E85
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Re: So what are you Guys reving your 2.5L's to?
Quote:
Originally Posted by
Loudexploder
I just bumped it to 9.3:1
I wanted to be around 10-10.5 but didnt want to wait on custom pistons
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Ah so it is now an interference engine but that is AOK.
increased mine but still wanted to stay non-interference, for now
So you are at 9.3:1 including chamber port?
Re: So what are you Guys reving your 2.5L's to?
Quote:
Originally Posted by
chromguy
Ah so it is now an interference engine but that is AOK.
increased mine but still wanted to stay non-interference, for now
So you are at 9.3:1 including chamber port?
Im not sure if it is an interference engine or not as I havent checked that, but Id venture to say it was even before the new motor. The cam im using has a long duration and mid 500 lift which i think would cause interference.
The 9.3:1 is static compression, measured from bore, stroke, deck height, piston dish volume, chamber volume, and gasket thickness.
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Re: So what are you Guys reving your 2.5L's to?
While I used to take these tech articles seriously, nothing I've seen in winning engine combinations for drag racing has supported these claims. They specifically make claims about Drag racers wanting 1.8 rod ratios.
Real advice about 4 cylinder power production is, obtain as much displacement as possible without having the bottom end scatter at up to 12,000 rpms. Some boosted combinations do better with lower rpms, probably because the rods get way too beefy vs a 12,000 rpm N/A combination.
The idea that long stroke side loads the cylinder enough to hurt power production is wack. The pistons would all be wrecked in half a pass. Yes, rod ratio matters for the longevity of a road course or time attack car. Rod material quality has also improved over the last 3 decades.
http://www.minimopar.net/perf/longrodengine.html
Re: So what are you Guys reving your 2.5L's to?
With built bottom end, my 2.5 made 509 on 27psi at 6700 rpms!!
There are a few people who can vouch this thing likes to rev as they seen at SDAC.
build it right and it'll make power.
Re: So what are you Guys reving your 2.5L's to?
Quote:
Originally Posted by
Loudexploder
With built bottom end, my 2.5 made 509 on 27psi at 6700 rpms!!
There are a few people who can vouch this thing likes to rev as they seen at SDAC.
build it right and it'll make power.
:thumb:
yup. it revs.
i mean if a k24 (not much less stroke... 3.9") can rev to 10k, a 2.5 can handle 7k.... hell, i money shifted mine in 2007 and hit 8800 without the bottom end coming apart. bottom end is still untouched since 2004. spit a few rockers on that exercise though....
Brian
Re: So what are you Guys reving your 2.5L's to?
Quote:
Originally Posted by
Aries_Turbo
:thumb:
yup. it revs.
i mean if a k24 (not much less stroke... 3.9") can rev to 10k, a 2.5 can handle 7k.... hell, i money shifted mine in 2007 and hit 8800 without the bottom end coming apart. bottom end is still untouched since 2004. spit a few rockers on that exercise though....
Brian
I have yet to spit a rocker, but I'm running some pretty stout springs. About 360lb open pressure.
I seen over 8600 when I spun at the track. LOL
Re: So what are you Guys reving your 2.5L's to?
That's some engine speed for sure.
Does anyone remember what Bill G's NA omni spun to? I seem to recall it being around 8K or so? I wonder what he did to make that happen. Granted, it was a 2.2, but I think the valve train modifications required would be the same?
Re: So what are you Guys reving your 2.5L's to?
Quote:
Originally Posted by
cordes
That's some engine speed for sure.
Does anyone remember what Bill G's NA omni spun to? I seem to recall it being around 8K or so? I wonder what he did to make that happen. Granted, it was a 2.2, but I think the valve train modifications required would be the same?
Valve train mods would depend on valve sizing, size of camshaft, and ramp rate so that you can avoid valve float.
2.2 would also require less camshaft go make power at the same rpm as a 2.5.
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Re: So what are you Guys reving your 2.5L's to?
Quote:
Originally Posted by
Loudexploder
Valve train mods would depend on valve sizing, size of camshaft, and ramp rate so that you can avoid valve float.
2.2 would also require less camshaft go make power at the same rpm as a 2.5.
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Interesting. Thanks for the info. Now I really want to know about Bill's ride. Hopefully someone can post up about it. That thing screamed.
Re: So what are you Guys reving your 2.5L's to?
Quote:
Originally Posted by
Loudexploder
I have yet to spit a rocker, but I'm running some pretty stout springs. About 360lb open pressure.
I seen over 8600 when I spun at the track. LOL
yeah i remember you saying that.... (8600)
I was running stock springs back when I tossed rockers.
Brian
Re: So what are you Guys reving your 2.5L's to?
Definitely one of the most interesting 2.5 builds out there.
Will be very interested to see how it does as you approach 600whp.