-5's Vs Rs's On A Larger Then Stock Motor

[BoostdR]

They are more like 260 272 when you work out advertised duration.

The 260 10.8 would work. Just need head machining for the lift.

[BoostdR]

Just had a search for the Gibson spec sheet I had done...got me thinking about them again. When I find them I will post them up for interest sakes.

What are peoples thoughts on staggered cams?

Edited February 3, 2011 by BoostdR

[R31Nismoid]

gibson used big cams because they work - unless gibson was smoking the same stuff as jim souvas & rob ward

They were also running a Race car.

Race car = always a bad example.

[NickR33]

Gibson ran them because they spent hours at 5000+rpm... no need to be efficient at lower rpm if your never there... a street car that's constantly up and down through the rev range and on and off boost is a different story

the point of going bigger displacement is to increase drivability... why ruin it again with massive cams?

[Rolls]

gibson used big cams because they work - unless gibson was smoking the same stuff as jim souvas & rob ward

They probably had very interesting head work and a bunch of other things though.

[Marko R1]

They probably had very interesting head work and a bunch of other things though.

most definitely, being a race car you could only imagine the r&d that went into the head work.

however, my head is ported to specifically match my cams with bigger springs but still runs stock valves/retainers/buckets.

its simple - if you want more power you need bigger turbos & cams etc

each to their own, im just vouching from what ive learnt from others that have been mucking around with gtr's when i was in high school

[r32-25t]

But on a street car its not about peak power, it's about how low you start making decent power (power under the curve)

There is no point having a car that makes 400kw if it doesn't do anything till 6000rpm a car that makes 380kw but makes good power at 3500rpm

Will always be faster on the street and much nicer to driv and that's what Paul is trying to achieve

Also one look at Pauls dyno sheet before and after e85 shows there is a air flow restriction

Brett

Edited February 4, 2011 by r32-25t

[R31Nismoid]

But on a street car its not about peak power, it's about how low you start making decent power (power under the curve)

There is no point having a car that makes 400kw if it doesn't do anything till 6000rpm a car that makes 380kw but makes good power at 3500rpm

Will always be faster on the street and much nicer to driv and that's what Paul is trying to achieve

Also one look at Pauls dyno sheet before and after e85 shows there is a air flow restriction

Brett

Couldn't agree more.

[Nee-san]

Just had a search for the Gibson spec sheet I had done...got me thinking about them again. When I find them I will post them up for interest sakes.

What are peoples thoughts on staggered cams?

Also keen to hear what people think of staggered cams as it's pretty hard to get a straight answer anywhere !

For what it's worth my car has 264 and 272 duration with a 10.2mm lift for both and after 5000 RPM is an animal (33N1 turbo's supposedly)

[BoostdR]

I have a few examples for staggered cams

2.7 750ps 88kgm 8.6:1 T618Zx2 IN 272 EX 264

2.7 830ps 95kgm T88 IN 280 11.8 EX 290 11.8

2.6 800ps GT3037S 56 x 2 IN 272 EX 264 9.7

2.6 600ps 60kgm GT2530 x 2 IN 260 10.2 EX 253 9.5

2.6 614ps T517Z 10cmx2 IN 246 9.7 EX 272 9.7 (TRUST demo car)

[black bnr32]

any graphs?

[Piggaz]

I have a few examples for staggered cams

2.7 750ps 88kgm 8.6:1 T618Zx2 IN 272 EX 264

2.7 830ps 95kgm T88 IN 280 11.8 EX 290 11.8

2.6 800ps GT3037S 56 x 2 IN 272 EX 264 9.7

2.6 600ps 60kgm GT2530 x 2 IN 260 10.2 EX 253 9.5

2.6 614ps T517Z 10cmx2 IN 246 9.7 EX 272 9.7 (TRUST demo car)

Grrr... No consistancy there.... Some cars have bigger inlet and some cars bigger exhuasts!

[NickR33]

I reckon the only way to do it is to have your own dyno, a bunch of different spec cams and plenty of free time!

[R31Nismoid]

Problem is dyno aint the be all with cams as it comes down to head work, application of the car and what you want (ie certain tracks even benefit from certain aspects).

Remember Racepace cars were faster with smaller cams - which didn't necessarily look favourable on a loaded dyno run.

It's the on/off throttle stuff that you can't see sometimes... and hence its very much a topic that will go forever IMO given there is clear rules like there is with say turbos and your choice/power etc

[Nee-san]

pretty much, everyone has a different opinion on staggered cams.

[Rolls]

I think a great way to show response on a dyno would be to hold the revs at 5000 then plant it, surely that would give some indication of response?

[elrodeo666]

Marko,

Head is ported.... how good of a job is anyones guess. Does it match the turbo's and cams? I have NFI

Cams as Ash has said a very touchy subject.

Tangomatt used baby cams (Ok he had vcam but meh)

Marcus used 264's @ 9.7 and got a mega result

I am using 270's @ 10.25 and it comes on later and makes less grunt.

Gav is using 272's (i think)

Ah we could go back and forth about this.

Hey Paul

Thing is I had major head work done on my engine and all done off HKS race specs.

I'll flick you some pics of that head next day or so which has same port/polish as the one one my engine.

[BoostdR]

Problem is dyno aint the be all with cams as it comes down to head work, application of the car and what you want (ie certain tracks even benefit from certain aspects).

Remember Racepace cars were faster with smaller cams - which didn't necessarily look favourable on a loaded dyno run.

It's the on/off throttle stuff that you can't see sometimes... and hence its very much a topic that will go forever IMO given there is clear rules like there is with say turbos and your choice/power etc

I agree,

I feel the setup would define how the inlet and exhaust needs to be balanced.

It looks to me like the guys with bigger exhaust housings used a larger exhaust cam ie T88 and trust 10cm. Where as the guys with turbos that spool well had larger inlet cams....possibly extending high end power.....I would expect all at the aim of max average power as all the cars in my example are track built.

Matt

[NickR33]

Problem is dyno aint the be all with cams as it comes down to head work, application of the car and what you want (ie certain tracks even benefit from certain aspects).

Remember Racepace cars were faster with smaller cams - which didn't necessarily look favourable on a loaded dyno run.

It's the on/off throttle stuff that you can't see sometimes... and hence its very much a topic that will go forever IMO given there is clear rules like there is with say turbos and your choice/power etc

yeah I'm pretty sure race teams (like Gibson) would have different spec cams for different tracks... dyno is handy for getting the cam gears dialed in for each particular setup though... having your own track to then tune it in real world situations would be nice too:)

anyway its all old tech now... fixed cams profiles are only ever at peak efficiency at a certain rpm point... all modern cars run some sort of variable system that is far superior to our dinosaur RB's lol... unless you pony up the cash for a vcam system... so its all a compromise and as you say its all dependent on your intended use for the car and the rest of the setup

also we haven't discussed any potential torque increases or decreases at certain rpms etc

endless debate... but at least its a distraction from doing work

[sneakey pete]

I think a great way to show response on a dyno would be to hold the revs at 5000 then plant it, surely that would give some indication of response?

Dyno's don't read time, they read rpm vs power (or variants of that). You can see the power under the curve, but you can't really tell the actual response time of the setup.

Edited February 9, 2011 by sneakey pete