272 10.5s To Big For 500rwhp?

[kastin]

As the topic states, are jun 272 10.5's to big for 500 rwhp? running a gt3540 .82

is that going to make a laggy street car? i'm not really after peak power just meaty midrange.

[CruiseLiner]

ive got jun 272, 11.35mm lift cams on my t04z rb26 and its great, not laggy and damn does it sound tough at idle

[shanef]

cruiseliner u mean on ur rb27

what has the 272 11.35 lift cams done to the powercurve?

[CruiseLiner]

cruiseliner u mean on ur rb27

what has the 272 11.35 lift cams done to the powercurve?

i dont know compared to other cams as ive never tried any others as yet, but heres a dyno graph on 18psi if that can shed some light

oh and yes its a 2.7 but that shouldnt make a big difference i dont reckon, and that is with a 8500rpm revlimit

Edited February 18, 2007 by CruiseLiner

[kastin]

Well this is in a 3l limited to 7000

[kastin]

anyone else with some input?

[T04GTR]

well that curve is very nice. im contemplating getting tomie 280/11.5's in mine with a to4z

[shanef]

well that curve is very nice. im contemplating getting tomie 280/11.5's in mine with a to4z

what will they do to the power curve?

[Gav]

anyone else with some input?

I'm now running 272 "STEP2" cams (around the 11mm lift) on both inlet and exhaust.

The originally I was running a 264IN, 272EX, however changing to 272 on both I gained both top end and midrange. See the following graph

Dyno Graph

Unfortunately it's shown in speed rather than engine RPM, however you get the idea.

Oh yes - the idle is really "tough" now

[kastin]

I'm now running 272 "STEP2" cams (around the 11mm lift) on both inlet and exhaust.

The originally I was running a 264IN, 272EX, however changing to 272 on both I gained both top end and midrange. See the following graph

Dyno Graph

Unfortunately it's shown in speed rather than engine RPM, however you get the idea.

Oh yes - the idle is really "tough" now

What turbo are you running? t04z?

and what was your redline?

Edited February 22, 2007 by kastin

[Gav]

What turbo are you running? t04z?

and what was your redline?

I'm running low mount GT-RS terbs on an HKS 2.8L kit.

Redline for that particular run was just over 8K, but I've had the motor spinning to well over 9k and it still felt like the power curve was flat.

Further details at:

Dyno and Engine Specs

[Denver]

sydneykid can answer this better, as i posed a very simular question to him a while back..

but in short, for every bigger cam profile yo go, expect the useable rev range to move higher, 256's will come in at say 4k rpm, 264's at 5k rpm and 272's at 6...

just means where thye become effective moves a lot higher..

i perosnally went for 264's on his recomendation, and with positive pressure being created by 2800 rpm on a rb26 with a gt3040R, with stock timing and no cam gear tinkering, it seems like advice well said..

252/264 for low end and mid range, 272 if you wanna go drag racing or want big top end

[shanef]

sydneykid can answer this better, as i posed a very simular question to him a while back..

but in short, for every bigger cam profile yo go, expect the useable rev range to move higher, 256's will come in at say 4k rpm, 264's at 5k rpm and 272's at 6...

just means where thye become effective moves a lot higher..

i perosnally went for 264's on his recomendation, and with positive pressure being created by 2800 rpm on a rb26 with a gt3040R, with stock timing and no cam gear tinkering, it seems like advice well said..

252/264 for low end and mid range, 272 if you wanna go drag racing or want big top end

that's all well and good in theory..but look at gav's dyno results, he gaind power everywhere. surely they totally contradict wat SK recommended you?

gav, dont spose u mind dropping in some 264's for comparison sake?

[kastin]

i think i read somewhere that every 10 Degrees above standard moves peak power 500rpm higher but i dunno if this is true, But if the cams become effective at 6000rpm that leaves 1000rpm till orange line 1500 till red.. not really much fun..

i was hoping they would really kick around 5000 and hold to well past redline..

Gavs graph has sure kicked a few stones, i mean he got more midrange and earlier moving from a 264 to a 272 inlet cam!

Suppose ill have to wait and see as the heads finished..

Edited February 22, 2007 by kastin

[Gav]

I suspect that my results are more a case of increase exhaust flow was required to spool up the larger GT-RS terbs. In otherwords, matching the cams to the terbs.

I'm sure there was also more experimentation done with cam timing at the same time, so it may not be simply a case of achieving the improvements with simply going to a longer duration camshaft on the exhaust.

[shanef]

gav, in ur opinion, do you feel the GT-RS's will make 700-750hp?

[2BNVS]

i got JUN 272 with 9.7mm lift goin in mine in a week or so its rb26/30 so we'll see how that goes, running t04r/66 turbo

ben...

[kastin]

awsome keep us posted!

[Gav]

gav, in ur opinion, do you feel the GT-RS's will make 700-750hp?

I can only speak from my personal experience. I'm certain on my 2.8L motor 600 rwhp would be possible maybe up to 620 with all the supporting mods and optimising cam timing for top end power rather than for mid range as in my present case.

I'm sticking around the 550 rwhp mark, however, as the car is now "balanced" to accomodate this level of power (i.e. 680cc injectors, single high volume fuel pump, sprung centre clutch etc). To go beyond where I am will really detract from making this an enjoyable drive on the street (and cost a swag more dollars and tuning time).

Sorry - the above is a long winded way of nme saying that I believe that GT-RS won't get you into the 700-750rwhp range IMO.