MadBill wrote: ↑Mon Apr 13, 2020 9:59 am
Coincident with the introduction of GM's Gen 2 'F' body in 1970, oil system problems arose with a lot of Pontiac Trans Ams, with the highest proportion of complainants being in Quebec, Canada.
The explanation turned out to be that the Pontiac chassis engineers had aced the tuning of their version of the shared-with-Camaro platform but not so much the engine guys. Unlike the ubiquitous SBC, the Pontiac oil pan sump and system couldn't handle long sweeping high-g corners without oil starvation and for some reason a higher number of French Canadian customers were enthusiastically using the cars to their limits...
Yup, go fast around a clover leaf ad the lifters would clatter near the apex. Most T/A owners had Accusumps installed. I went the SBC route.
Not sure a Spintron would solve it, though.
Also, the focus on the topic seems to spintronning out of control...
Rick! wrote: ↑Mon Apr 13, 2020 11:01 am
...
Yup, go fast around a clover leaf ad the lifters would clatter near the apex. Most T/A owners had Accusumps installed. I went the SBC route.
Not sure a Spintron would solve it, though.
Also, the focus on the topic seems to spintronning out of control...
There is an inverse problem with failures. The observed failure can have more than one possible cause.
A fully instrumented car on the track is different from a fully instrumented engine on a Spintron or AVL Schrick active dyno. It is important that failure analysis engineers not lose sight of that.
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hoffman900 wrote: ↑Sun Apr 12, 2020 2:45 pm
This podcast is worth listening to:
Hopefully Mike can put something together as well along the same lines. Would love hearing from different perspectives.
I came way from the video with many interest thing. But since Torque verses HP has been a topic of discussion here and many other forums. I found it interesting that Billy talked about HP a few times but more often talked about what happened or how the torque curve was effected.
frnkeore wrote: ↑Mon Apr 13, 2020 4:28 pm
HP is a formula, torque is what a engine actually produces so, if you can keep the torque curve from falling, you automatically increase HP.
Above 5252 torque can drop and HP can still increase. When HP starts to decrease depends on the angle of the downward slope of the torque curve.
Stan
ab-toms-hp-383.gif
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Thanks, Stan.
Yes, I'm well aware of that. My point was that, every little bit of drop off that you can save, as the torque curve drops, you get increase HP and performance.
So, if you see less decline, you have increased the HP and you don't need to know the actual HP, just that the torque has increased. Unless your shooting for a particular HP figure and not wanting to vary it, it's not very important.
I believe I heard him talk about shifting the torque curve. I took that to mean what someone told me they had done. Which without getting to details was to shift their basically same torque curve to a higher RPM.
Stan Weiss wrote: ↑Mon Apr 13, 2020 7:16 pm
I believe I heard him talk about shifting the torque curve. I took that to mean what someone told me they had done. Which without getting to details was to shift their basically same torque curve to a higher RPM.
Stan
One thing I found interesting about that pod cast was in relation to shifting the tq curve on nitrous applications, the one I dynoed with a "nitrous" cam had a growing tq curve above 5250 na but on the bottle tq dropped like a normal na engine.
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frnkeore wrote: ↑Mon Apr 13, 2020 6:35 pm
Thanks, Stan.
Yes, I'm well aware of that. My point was that, every little bit of drop off that you can save, as the torque curve drops, you get increase HP and performance.
So, if you see less decline, you have increased the HP and you don't need to know the actual HP, just that the torque has increased. Unless your shooting for a particular HP figure and not wanting to vary it, it's not very important.
If you look at sportbike engines, you realize they are really just high rpm torque monsters...
Here is a stock Ducati V4R:
The slower torque falls off after peak, the better. That's the difference between a very highly developed race engine vs. a typical Car Craft type street build.
hoffman900 wrote: ↑Tue Apr 14, 2020 4:21 pm
The slower torque falls off after peak, the better. That's the difference between a very highly developed race engine vs. a typical Car Craft type street build.
Very useful tool. But a question popped up: To get the most accurate data from the spintron testing, is it normal to heat the oil and head/block to normal operating temps, say 200F? Would be very useful for more accurate real world comparisons.
Take note of what Kevin wrote about WWII German V12 aircraft engines and Honda's RC30 (early '90s), then see how they fixed fluctuations in angular velocity of the camshaft .
For reference, the maximum intake valve acceleration of 55mm/rad^2 is 0.0377925625"/*^2 , and that also meant they had the ability to spin to 20,300rpm.
Compare that to Mike's NASCAR restrictor plate cam circa 2006:
"Aggressive" depends on the application.
Here's the numbers at the valve on a 3 year old NASCAR restrictor plate cam.
300 @ .0001" Valve Lift(Seat)
262 @ .050" Valve Lift .000882" Peak opening valve acceleration
.000512" Peak nose valve acceleration
.000797" Peak closing valve acceleration
That cam was mild compared to some others it ran against
Not being limited by valve springs is a nice thing.
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