Vlad's rides thread

[vlad01]

I'm hoping that with some custom made tall rocker covers to suit the YT Platinum adjustable rockers based on the factory covers (to use the OEM o ring seals and captive bolts/rubber grommets) so that the bolts are the originals and down low on the head, I might just be able to squeeze in the covers with the smaller diameter VH512 dual booster that my VP S already has and be able to wiggle them off and out without drastic measures such as dropping the engine and K frame down to get them off in order to adjust the lash.

This pump would give me all the reason to keep the booster and have great brakes, as the cam I have on the shelf would have next to no vacuum, so much so it would be an improvement to delete the booster


Also I realized that one thing no one ever talks about or knows the answer, is with a big cam does any of the vac operated actuators even work on the HVAC?

Well this would 100% negate that issue and they will work before you even start the engine!

[v6bucket]

If the LSA of the cam isn't too low, you will have vacuum for HVAC system, have a look at most cams for LS engines, generally 110° +.

[Charlescrown]

That's a point. I remember the old Falcon GT having a fairly large reservior for vacuum but I'm sure it was only for brakes and all the actuators were cable operated. I'd try it as it is with the cam and it may be enough vacuum to operate them normally. If not maybe make up a vacuum reservior.

[vlad01]

If the LSA of the cam isn't too low, you will have vacuum for HVAC system, have a look at most cams for LS engines, generally 110° +.

Easy enough to T in the HVAC vac line to the pump/boost line. In fact I read it's a good idea to T in the engine vac supply line too with a check valve so that in case of a pump failure or slow recovery the engine can add some vacuum, but outside of those conditions it never will open the check valve, it's just a worst case backup.

My cam is 106 lsa but the overlap is somewhere around 90 deg as the 50 thou duration is 262 deg. Def needs a pump.

[Charlescrown]

How much vacuum do you expect to get with the cam. My guess about 15 inches @ idle which is probably more than enough to work hvac controls.

[vlad01]

Little idea really, but googling similar specs on similar per cylinder displacement, something like 8-10" is what others get but I don't know what that is in kPa. I don't understand yanky units.

[immortality]

What sort of KPa reading do you see at idle? Between 60-70KPa?

https://convertlive.com/u/convert/inche ... opascals#8

Use the converter to work out a KPa value but then subtract that from 100Kpa (atmo pressure).

[vlad01]

I haven't built anything yet. I have the cam and a few bits already but it's a far away project that I am slowly planing and working out the details before I start.

[vlad01]

Today I changed the thermostat in my shitbox to: A: negate peak temps after holding mid to high rpm and light load for prolonged periods which lead to a burst knock condition. Seems to happen at 100c or more coolant temps and high ambient air temps/low air flow (stuck behind cars or trucks) When coolant it closer to 90-95 or below it doesn't really occur, even with the other conditions met. B: I notice a sudden and significant jump in fuel economy once the ambient temps are at or above high 20s to 30c. I hypothesize that in traffic conditions holding lower gears/higher rpm to be able to control car speeds with only the throttle (engine braking), that the thermostat is mostly closed due to the overkill that is the commodore cooling system, this in turn adds additional parasitic load of the water pump loaded against the thermostat. At higher temps the thermostat I suspect is more open, so at these higher rpms the pump puts less load on the engine. The jump in economy can't be explained by the tune or AFRs etc...

While checking all the temp related settings worked to reflect the lower operating temp of 80 to 89c, I finally got around to testing the lean cruise ARFs by making an averaging histogram in the ADX, so I can get an overall L/100Km. I used the "running average" as that gives the whole data set average instead of 100 points when selecting "history average".

I ran the same exact stretch of road at the most steady speed and TPS I could. I logged each run with a different LC AFR. I "marked" the start and stop of the road section by stabbing the throttle breifly at each point so I can see tbe point in the logs. I took only the clean section between that on the logs.

I drove a loop so I always headed in the same direction.

I got this table. Considering that I had a windy day and no cruise control, I think this data is pretty damn consistent.

What I found is that, at least in a real world condition, LC makes f**k all gains, but the data shows a trend that there are tiny gains at least up to mid 16:1. It seems most of the expected gains in the AFR reduction is lost due to lower vac and higher TPS.

Lean cruise testing..PNG (7.39 KiB) Viewed 4438 times

[immortality]

Did you also play with the timing for lean cruise? A lean mixture should burn slower so will want a little more timing advance.

On the ecotec tunes lean cruise goes out to about 18:1 but it also adds a couple of degrees of timing. I dropped mine back to about 15.4:1 but I forgot to take out the extra timing and I spent ages going backwards and forwards on the main timing table as sometimes it was fantastic and other times not. I then took out most of the extra timing and now lean cruise seems better as well as normal. It is a lot of fucking around though as there is nowhere quiet I can test so no 2 runs are exactly the same.