again, a compression check is the most direct method of checking how healthy your engine really is

idle vacuum can vary significantly as a result of higher than 700 rpm idle speed, a free flowing intake (i.e. no air box), and how aggressive your street port might be....of course low compression and engine deposits can also cause low vaccum, but there is no way to distinquish that from the former....without a compression check, you don't know

my almost new street ported engine goes as low as 12 with a loping 600-700 rpm idle....

am I worried? nope....it pulls like stink on the top end

 

I run a 20 at idle, but oddly my boost is only 8 then back to 5 after like 4000rpm. I was curious does anyone know what is going on? Iam guessing my vac hose are messed up or I need to get new turbos. Anyway hope someone can help. Thanks

 

Im pulling -11-12 psi at 750-800rpm on my new rebuilt

 

I just put in a new motor with 3mm ceramic seal and a street port. I also have block off plates and no air pump. I only pull around 10 at around 750 rpm. Is this normal for a new engine?

Matt

 

I dunno..I took a look at mine today and I'm pulling 15-17 psi on a Pineapple Racing Small Streetport with the stock turbos.

So this is a good thing?

 

angel,

question is, who cares? when are you strapping her to the dyno?

 

Well..

I do!!! :p

I've been staring at the boost gauge all freaking day long trying to get that damn idle fluctuation crap stopped. At least SOMETHING makes me feel good about it today.

I'm getting her dyno'd in about two weeks at Xcessive Motorsports by Ralph after he finishes moving the dyno over to Ground Zero.

That should give me some time to break her in, and finish up the little things.

I just finished cleaning out the condensation in my front turn signals. Whew..looks a helluva lot better now.

 

the FD

it isn't a car, it's a life

 

 

I should be doing quite well then because I have 17"hg at idle 800rpm on a motor with 121,000miles Huoah

 

Idle vacuum is not a useful way to compare cars.

If you had 17 in Hg at 750 RPM, and then you start getting a bouncy 13 in Hg, that might tell you something useful.

But someone might pull up in a car with a healthy engine that has a big port job that has the same idle.

Or someone who lives in Denver might post that they have a stock port engine in very good condition that is only pulling a smooth 13 in Hg at idle.

Then someone in Death Valley with a 1100 RPM idle, crappy gauge, and a tired motor posts that he is pulling 20 in Hg at idle.

Lots of numbers, very different reasons for them. Idle vacuum is not a useful way to compare cars. I drove my car across the country (MI to CA) and witnessed very different idle vacuum numbers depending on where I was. I assume it had something to do with altitude (as it seemed to be lower in the mountains), but it could have been some other things, too.

-Max

 

the thread is back....