My 3,2 has a MaxHPKit Multi-board, modern Bosch 715 injectors, Bisimoto exhaust, VP Madditive, and I routinely go past 7,000 RPM. I think fuel cut off is 7,200 but on a 30 year old tach, who knows. Car weighs in at 2,740 WITH ME IN IT so redline comes quick in 1st, 2nd, 3rd. I have zero concern. Porsche designed racecars that got fattened up with creature comforts so they'd sell to the public. They are right at home being abused. Sorry, it's the truth.

+ 1, for Metzger

M637 intake valve is 930.105.409.14

Ti valves would be lighter

The engine speed is governed solely by the DME's control of the fuel pump which it can switch on or off

Here's a graph of 2 different engines in an SC chassis w/ stock SC trans
the stock 3 liter needs to be shifted where the accel curves cross, if the thrust was graphed it would show the same crossing points.the 3 to 4 shift would need to be @5450, the 4 to 5 @5600

The 3.6 curves don't ccroos so this engine would be run to red line for every shift

http://forums.pelicanparts.com/uploa...1509573829.jpg

The whole goal of a shift is to maximize thrust or acceleration in the next gear

Excellent plot to illustrate the issue.

Holy crap is a stock 3.6 that much stronger than an SC motor?

FWIW - Yes agree 100%, let's not be like other car forums (we usually are not). E.g. I did X to my car and therefore it is OK for everyone - of course these sorts of statements usually come from non-experts.

That acceleration looks pretty strong, on paper, at almost 25 ft/sec^2. Isn't gravity acceleration 32 ft/sec^2?

thanks for the part number... interesting that it starts with a 930?

im not a big fan of Ti valves on an old school street motor intended for high mileage usage. the hollow ones have better heat transfer too but and being factory has been tested for durability.

surprising that its fuel shut off since the cut off is pretty abrupt. i think my chip is set at 7000-7100 for the rev limiter.

yes
both of the dyno plots come from healthy versions of each type
the 3.0 is a bluprinted SC race motor the 3.6 is a blueprinted 993 nvr w/ RS cams/valves & chip

Hollow aren't particularly efficient for heat transfer, they fill them w/ Na for that, then use them mostly on the exhaust only

I mentioned Ti mostly because a friend had his 3.0 liter race motor built w/ Ti valves, the thing is a rev monster 8k rev limit

thanks for the part number... interesting that it starts with a 930?

im not a big fan of Ti valves on an old school street motor with stock valve seats intended for high mileage usage. the hollow ones have better heat transfer too but being factory has been tested for durability would be an added benefit.

surprising that its fuel shut off since the cut off is pretty abrupt. i think my chip is set at 7000-7100 for the rev limiter.


I luv these graphs of yours. I have an opposing view of this respectfully. from the look of the 3.0 it looks to be vitally important to shift out at 1st and 2nd at redline.

what that graph leaves out is the shifting time of the slow 915 box which most likely will fall right on the dip of the 2nd gear curve. anyone who drives these cars can definitely feel this by the seat of his pants.

as you can see from the 3.6, where you shift isnt as important since the next gear falls on steep constant acceleration ramp. in the real world, torque wins over hp/weight for street driving especially with stock gear ratios. but power to weight make you an internet hero despite a huge hole in your acceleration curve!

all the best pf

Where you shift in the 3.6 is actually very important.

For example, if you shift from 4th to 5th at 110 mph you go from roughly 9 ft/s2 to 7 ft/s2. In terms of performance, why would you like to upshift to have less forward acceleration? If one holds 4th up to the redline at 120 mph, acceleration is still stronger in 4th than 5th.


The plot shared by Bill Verburg is the ultimate real world performance "metric" since it shows car acceleration in each gear at each car speed. One figure summaries such as max power, max torque, or maxhp/weight can all be useful to convey an idea of car performance but there are many caveats that one should take into account when using them.

Acceleration vs speed plots represent the performance envelope of a car and are very useful in motorsport to optimise car performance.

Don't get me wrong, I run mine to redline all the time, once it is fully warmed up. I just see no point in going past that for the 3.2 engine with a stock transmission. I don't drag race at all. I do my fast driving on the autocross or track events. Running to 6,400 RPM through 1st and 2nd will get me to 60 in enough of a hurry.

On the track at Charlotte Super-speedway was a blast. I would go from the infield up to the banking in 2nd gear and stand on the gas. Run to redline, shift to 3hrd, run to redline shift to 4th run to redline (about 115) and stick it in 5th and cream towards the big curve ahead. I will admit I was a wimp and eased back on the throttle to go through the banked curve in tipple digits. Nail the brakes hard and get back down to 2nd and on to the infield. I don't know what max speed was in my car. The track is about 6 inches wide to my senses even though the pros go through there three cars wide at 200. I did notice above 5,000 RPM in 5th. It was fast enough for me.

http://forums.pelicanparts.com/uploa...1509650829.jpg

I will have to dig to find the photos of that one. Here is me at Lagua Secca.

i dont think so... extra displacement, quicker shifting G50 and broad torq curve over the SC has the 964 nearly always accelerating so it isnt as important to shift near redline as a SC. u can shift a 964 1500 early and still walk away from a sc without trying.

thicker torq curve of the 64 allows more flexibility in were u can shift over sc without as much detriment to acceleration. of course if you want shift at redline on the 64 for max accel, but if you dont it dosent really fall into the hole of the torq or accel curve like that of the sc. hence my reasoning for not having to shift at redline or more as often.

yes look at the graph, the acceleration curve on 964 is nearly constant in each gear till the very end then it dips. if you shift at peak torq as some have suggested in the sc, you are actually decelerating again before the surg in 2nd and 3rd.

old school sc arent necessarily slow but you have to beat em like a step child to get em to move :-)


all the best

If one doesn't want to drive that 964 to the maximum of its capabilities then I have nothing to say. There are many ways to drive a car suboptimally :D

If one wants max acceleration, the shifts need to be just before the limiter.

+1 agreed ! cheers