Brand new atkins motor super low vaccume -10
 

Hi

Ok so i just started up my fresh rebiult atkins engine it has a mild street port 3mm apex seals. etc etc anyway i only seem to have between -10 to -14 vaccume at 900rpm idle?? is this normal??? and its steady vaccume and steady idle. timing is dead on.

Yeah, I'd say it's fairly normal for a ported engine with used housings. Vacuum is a reflection of compression to a degree, and compression is always weakest with rebuilt rotaries right after startup. Give it a couple thousand miles and it will come up a few inches. Even the tightest built rotaries with stock ports only generate about 16-17" at maximum (idle under 1k). Ported rotaries usually make 12-15. Weak compression rotaries, even with stock ports, can make as low as 10-12.

yeah my motor i had rebuilt a while back had weak compression for some time when we first fired it up! it took about 1000 miles and it started to jump up to par.. sucks at first cause ya feel ripped but it comes back! at least mine did

My motor from mazdatrix makes -19

Your idle is set too high or your gauge is off.

used housings you assume there used these are brand new rotor housings eveything is brand new in the motor other than the e-shaft. hmm and i have apx 1k miles on it well a bit under that and it vac has not come back up im going to do a compression test and well see what kinda numbers ill get. Also when its fully wormed up i get maby +1-2 -vac more.

hmm also where do you guys Recomend running the vac gauge from. what nipple and or how do you have yours set up.

On another note im NOT happy with atkins rotary's work at all my front cover is now leaking oil and alot (like over 3k) of $ was shelled out for this rebiuld. dose anyone know what the warrenty covers i forget. Im not trying to slander this company by any means. Im just speaking from personal experiance. i should of had RotaryResurrection or mazdatrix or pinnaple racing do it or something.

Shoulda had me do it. :D

ok Chris I have no paperwork in your file or the shop for that matter of you ever buying it from me.

If this is the engine I am thinking of you bought it with a car that this engine with it..

So the warrenty is ONLY given to the first party that bought it and you are not that person ... {this will be twice that I have told you this, if I am correct.}

Now if I am wrong let me know and I will admit it with no problem but you have to prove it first..

If you give me the #s on it the engine I can post up what this engine got in the rebuild...


I also have all the warrenty posted on my web site {on what it will and will not cover} all you have to do is click on the link below...

http://atkinsrotary.com/index.php?pag=40-1

Dan

My stock port was 18 at 850 RPM. I thought that was too high and I double checked with different gauges and they both read the same. It is possible to have a motor pulling some high nice vac numbers.. I believe mazda "spec" is 15

you can be pulling high vac number when your intake is restricted, old air filter, etc...

Not true
Im guessing you have never seen a fresh built Rick Engman engine
(aka Mazmart). Any day of the week it will pull 17+ inches ported or not. Unfortunately new parts, 30+ years experience, stout compression and alot of vaccum dont = cheap engine build. Which is what 75% of the rx7 community want a "cheap engine rebuild". You pay for what you get.

vacuum also depends on timing, more advance, more vacuum....

Yeah, you're right. I guess I've yet to meet anyone who's willing to put more money into the engine block than the whole car is worth. Obviously Rick is a legend and his skills or motives are not in question, but the whole "you get what you pay for" line of bullshit is getting old, especially when you see these 4 and 5 thousand dollar engines dropping just as fast as the 1 and 2 thousand dollar ones.

i usually get 15" from a street port at 950 rpms. my current bridgeport is pulling 14" according to the haltech at 1300 rpms.. at 1000rpms it's right at 11 - 12" only has 550 miles of break-in so we'll see if that comes up any, i doubt it tho.

to the OP.. is this a stock ecu? often during break in you will have to start pulling a little fuel out. if it's running pig rich at idle the vaccum will drop some.

"Dropping" you mean blowing up?
Most likey due to poor install, set-up, or tune/engine management or all of them combined not engine build.

topic is engine vacuum

What you pay for is a engine that pulls more than -10 to -12 inches of vacuum.
Great vacuum -17 plus under 1k idle can be a reality. Its called new parts. And thats not a personal attack on you in anyway.:)

When you purchase an engine from us, you are given a warranty packet, and tech tips, as well as tech support.
Please give me your invoice number, so this can be researched.

If this was purchased 2nd hand then you do not have a warranty as it is stated in the warranty that it is not transferable, there are no exceptions to the rule.

Making statements like your disappointed in our quality of work is not fair if your are not the paying customer. If you were, then this should be handled in a PM.

Ok, I guess I'm missing something. First you say its a fresh rebuild. Then you say you have 1000 miles on the engine. Unless you put 1000 miles on it in 5 days. ;)

Vacuum is a partial reflection of compression, but otherwise it really does not matter at all how much you are making. I dont care if you are pulling 32 inches at a 650 idle...it doesnt matter that much. I never really worry about vacuum, I check compression anyway. If compression is over 105 then I consider it a pretty healthy motor. If it is over 115 then I consider it damn strong. I have never measured more than 125, even in a "new housing, new parts" motor, and I have measured 120-125 in a "used housing, used part" motor in which the housings were very lightly worn and the engine had a few thousand miles on it.

And yes, tuning/install/setup plays a big part in which engines blow. BUT, people are just as likely to botch the install/tune on a 5000 dollar pineapple motor as they are a 1000 dollar one that I build. Which one would you rather them screw up? I can link you to 2 or 3 posts within the last couple of months, of users who say they had this expensive engine "built right with all new parts, built by one of the best" that is blown/defective within the first couple of years. Now they do not know what to do, as they sunk all the money into that one "do it once, do it right" engine.

Not only because I build budget setups, but as someone who works on his own cars and hundreds of other people's, I say "build it decent, put your money into the car and not the engine block, and treat it as disposable so that if in 2-4 years you need another, you won't be that bummed out". After all, I can build 2 or 3 strong blocks for what many companies charge for 1 "new housing, new parts" motor. Honestly my setups tend to last about as long, or longer in some cases.

But hey...for those of you playing with monopoly money and can afford the best of everything, well that is why there are these high dollar builders here to serve your wishes. Somebody has to keep them in business, I guess. Better them than me. :)

Well said :icon_tup: .

i agree very well said i will conciter this next time before i jump into an expencive atkins motor. I will preform a cold and hot compression check. and post results.

So are you going to post up the # on the engine???

Dan

So does on the PFC a reading of -310 to -295 @ around 1800 to 1950rpm mean low compression??? I was worried when it kept flooding...Idle is 10.1 AFRs and they stay there throughout the rpm band up to 4k rpm.
I modified all the maps and will log data later today... Looking for leaner AFRs w/retarded timing all over.

That's around 12 inches of vacuum, which for such a high rpm is really low, even with a hbp. What are the specs on your engine internals?

brand new engines takes about 1000 miles to seat properly. you should have good vaume then. good luck

i got a large street with my rebuild from banzai and it pulls 19" at 950rpm. 16" when my power hog of an e-fan comes on. and this was NOT with brand new housing or rotors. i keep my afrs around 12-12.5. timing is pretty well advanced though.