RPM redline

[quattrorunner]

I have a 77 3.0 turbo with sc cams and gt30r turbo. It pulls hard till I let off at 5500 rpm with good afr of 12.2 or so. Where can I rev to with this engine? Am I leaving some power on the table, or at least some ability to stay in the gas to higher rpms? Thanks

[quattrorunner]

bumparoo
I thought these were good revers is that so?
Just don't want to wind too far.

[cole930]

QR:

With the SC cams your power is going to start falling off around 5400 RPM.
After that point there is no more power just more noise, absolutely no gains
after that. I have SC cams and never rev past 6000 RPM. More RPM doesn't
mean your going faster it just means bigger pieces to sweep up when it blows.

You need a good IC and a good free flow exhaust, and then you will feel
some nice power gains with what you have.

Cole

[quattrorunner]

What you hate meth now? Your one of the reasons I got meth in the first place.

[cole930]

QR:

I consider WMI your ace in the hole. Your SC cams are what is going to
determine the usable rpm limit. Having the WMI will allow you to do it
with more cooling, more timing, more boost, more horsepower, and less
chance of detonation.




WMI ROCKS !!!!!!!







Cole

[jbrown]

I agree with cole930 , 6000 is the limit for sc cams. I had them in my car. I now have 964 cams which do still pull past 6000. I really think I like the sc cams better for street driving.

I also have meth in my car and run 15-16lbs of boost and run the 964 cams to about 6500.

[Schwarzeritter]

The factory SC camshafts aren't good past 5,500rpm to be honest. I've always felt the SC camshafts were really a low to mid range response camshaft NA or Forced induction and in a
3.3 I feel like the 964 camshaft profile is a little better for a driver who is planing to use mid to peak rpm's, but they are a nice balence between low and peak.

Of course all of the above, depends on the which modifications and if those modifications work well in conjunction with one another. Balence is the key here, and not focusing on peak numbers but rather how power is developed and for how long it is produced before well it falls off.

I only have one car left with Jetronic for giggles, everything else Porsche has fuel injection, a few things Japanese have carburettors for kicks and old school fun, thou I still use programmable ignition. So selecting a custom camshaft for my own needs or balencing performance is easier. More reliable.

There are of course always exceptions mind you, however you will find that Jetronic does not like high lift long duration camshafts and that this means you are sort of stuck to producing power within a spectrum you may not like. Beyond that you are now thinking about balence and mechanical durability. We're no longer talking apples and oranges, but rather gentlemen
die Ananas. ( Pineapple ) ...

So are you like on Jetronic or Standalone?
Are you trying to achieve more peak power or a wider spectrum of performance?
You could always focus on producing simply more power sooner and tailor the power
with in the limits of the camshaft. But this usually means you have the wrong set up already
for what you will want. ~_~...

[motorracer]

If I run mine hard I might see 7200 tires don't stop spinning before 6000

[cole930]

I agree with Mic's assessment.

When I first got my car I already knew how I wanted to use it. I don't
race, it's too expensive and I can't afford replacing broken parts. I
never drive long distances, there are far too many idiots out there
to be driving fast out on the highways. But, I do love quick !!!!!!!

My car is the perfect ride for me. I like old school so I still run the CIS. I
loved 934's so I have 934 headers, center mount K27S turbo, and 8:37
ring and pinion and shortened 2nd. and 3rd. gears. The old girl tops out
at about 145 but it gets there quickly. It has made grown men scream
like little girls.

Best advice anyone can get is, know what you want to end up with before
you start bolting on the parts.

Cole

[Tilikum Turbo]

Looking at the graph for the 3.3L turbo, right around the 6000 RPM, I would not run it past, even though the motors rev/redline slightly higher than SC's.


Of course your oil should be hot too...

[fredmeister]

There are 2 trains of thought going on here.

The engine physically should withstand revving to 6600rpm with stock internals. The limit typically being the rod bolts in the 3.2 and 3.3 engines which were downsized from the 3.0 liter engine design.

The point of revving beyond the cams ability to increase power is the other point brought up. Some trains of thought would be to look at your gearing and determine at what rpm should you need to rev to so that when you upshift to the next higher gear your rpm falls at torque peak. So if for example revving in third gear to 6200rpm gets you to 4200rpm in 4th when you upshift and thats the torque peak, then thats your target. This might rev you past the rpm of max hp in third gear but the end result is better in 4th.

Fred

[quattrorunner]

Oil tmrp is a whole other issue for me.
No I just simply want to know if it were worth while to go past 5500 rpm. If 6k is my number fine. I'll just keep it there. Not I'm looking at Coles latest hairbrained project. Geez cole, relax would ya?

[cole930]

I can't relax until I get this damn car done but I keep finding new s--- I've
just got to do !!!!



Cole

[pkracer21j]

I have a 3.0 turbo, 6k is your limit, CIS runs out of fuel and cams run out of breath. if you do efi and top end cams, then 3.0 turbos love to rev...7500 is lots of fun!