vacuum qt idle

[2GFWDbeast]

Just got my car back from being fully built. it has 9.5-1 pe srp pistons hks 272 cams sheet metal intake,and all the other parts turbo etc.... I know i have to break in motor for at least 250miles but the shop told me 500 miles and then to change the oil.My vacuum is at like 9-10 in/hg at idle, and idle is at 1000rpms. will the in/hg increase as the rings seat. Or is that how the vacuum is at idle with it being built and cams and what not. The system was pressure tested to 30psi with no leaks and vacuum tested.

 

[LiquidX]

No idea what you were listing with your compression ratio; "pe", what's that? My Delta regrinds at the HKS 272 specs has me idling at 18 inHg.

The oil should be changed after the first 20-50 miles after the preliminary oil cha ge after the idle start to flush out metal. Hope you have an inline oil fitter pre turbo or you will be rebuilding that one too most likely.

 

[2GFWDbeast]

sorry Je pistons and 9.5:1 on the pistons, i was typing this on my phone. Well the machine shop told me change the oil after 500 miles.

 

[RadDsm]

sorry Je pistons and 9.5:1 on the pistons, i was typing this on my phone. Well the machine shop told me change the oil after 500 miles.

You should definitely change it before 500.
Change it after the first start up/ run, at 50, 250, 500 and you will be safe.

 

[90moneypit]

Change it at 50 miles. You need to flush out all the assembly lube and any stray contaminants from the system as soon as possible. If you wait until 500 miles, that will mean 500 miles of 'dirty' oil in your turbo which isn't exactly great. I changed mine at 50, 500, and then drove cross country 2000+ miles. No metal in the oil after changing it at '2600' total miles. Invest in a magnetic drain plug for extra insurance though. I had an AMS machined bare block (which I still flushed several times before assembly), and took my time hand assembling everything with repeated tolerance checks, your machine shop (and mileage) may vary though. Oh for the sake of complete disclosure, I used no-name conventional for the first 50, Mobile conventional (not synthetic!) for the next 450 miles and 2600 mile (total) oil changes. At the 5000 mile point, I switched to Mobile 1 full synthetic and never looked back.

 

[2GFWDbeast]

Well for starters all I asked was about the idle issue nothing about oil changing. I got the work done at a machine shop who builds race motors for drag cars, hotrods etc... They have been in business for 60 years. The motor didnt have any metal shavings in it to begin with. Also they cleaned everything even if there was shavings its was cleaned.

Also theres already magnetic oil plug in it. And for the oil that is being used for the first 500 miles is high in zinc. If the shop doesn't know what there talkin about then they would have law suit after law suit and go out of business. Every shop has there opinions and ways of doing things. Thats why its best to just go to the same place instead of skipping around. I know a few indivduals that have brought there cars to several shops, and has had the worst luck motor after motor blowing, turbos blowing because of reduced oil feeds.

Im not trying to start a fight with anyone. All I wanted to know was is my in/hg going to read lower for the time being until my rings seat? I know with the 272 cams the in/hg typically reads a little lower, but 10 in/hg seemed a little low.

 

[LiquidX]

Give it time for everything to seal. By the way, it's not metal shavings from the build process that gets in your oil, it's the rings shaving on the walls and other metallic parts fitting themselves in.

The high zinc content is good for it's anti wear properties but it won't help against minute particles of foreign objects in your oil. There is a reason why we are saying to change it sooner and more frequent. Hopefully it's not synthetic oil they are using either...

 

[2GFWDbeast]

no its not synthetic. They went threw the process of why not to use it during the seat period.

 

[RT-AWD]

with 272 cams 9-10 is fine, thats what i've got with my 272 kelfords

 

[LiquidX]

with 272 cams 9-10 is fine, thats what i've got with my 272 kelfords

That's with Kelfords. 272 Kelford cams would be similar to 280+ HKS cams.

 

[El Cuervo]

When I had my stock cams, I was idling at like 18hg to 21hg. Sometimes it would go to 16hg and then to 19hg. When I switched to bc 272 cams, my vacume was at about 7 to 10hg. Then I went to kelfords and my vacume stayed the same. Almost like 1hg per 100 RPMs. This happened in both sets of cams. Yet we know that the bc cams are smaller than the k272 cams.

 

[2GFWDbeast]

thanks for the info. So explain this when a car gets fully built at a shop that has a dyno, do they drive the car for so many x amount of miles for the piston rings to seat before they dyno it?

 

[LiquidX]

Do they drive on the dyno after building, I cannot answer for some random shop. I can, However, say that there have been motors broken in a quarter mile at a time on the track.