hi,
checking out this forum for a couple months now, but never posted anything before
i went to a dyno today to get a baseline done. got 233hp and same for torque on a Dynamics Dynomometer dyno on 91oct, but here is my question,

my very PEAK boost was 17psi at 3800rpm's on all of the pulls and tapered down to 13psi by 7000rpm's. now i live in Colorado so the altitude was 5200ft, could the altitude be what caused the lower boost? how would altitute affect a "stock" car/boost?

after the pulls i asked the tuner why it seemed so low and he said that it "could" be the altitude but maybe a small leak (it was the end of the day so we couldnt check for a leak there. i did not get tuned i just needed a baseline before the first few mods come in. but with that said what seemed more weird is that his car (evo 8 mr) peaked at almost 21 when he did his baseline pulls when he first got it same dyno, same place, and same octane, so we are on the oposite sides of the scale (mine read low, his was high)

yes i realize that boost tapers but even the peak was some what low and i did search but there isnt much regarding boost and altitude.

my car is stock and i do not have a boost gauge in it yet (i did just order a Defi boost gauge a few minutes ago)

altitude was 5200ft, it was 71F temp, using 91octane. i have an evo9 with 1800miles on it



sorry about the long post
thanks for the help in advance

 

ya i would get lower boost when i would come home to colorado. where do get your dyno?

 

Your car is fine so dont worry about it. It is the altitude that is hurting you. I have the same problem when I take my car to LACR which is at 2700ft. Just get a MBC and you will fix the problem.

 

i went to this place in Boulder right off arapahoe and 55th if you are familiar with the area

 

also i am planing on ordering a XEDE from Vishnu, and from what i hear you can up boost with the tune, but would a MBC still be a good idea or can the XEDE take care of it???

 

Hmm... I'd be surprised if the boost level drops. I would think that the wastegate should reference atmospheric. Are your boost gauges getting recalibrated at altitude? Most recalibrate themselves when then turn on.

 

i dont have a boost gauge YET but the boost reading came from the actual dyno reading

 

ya i lived in colorado for 4 years tell i went to college now im down in texas and come back up during the brakes. i work at I70 and wadsworth at 3zero3. its a audi/vw tuning shop

 

The Xede will take care of it, it is a bad idea IMO to use a manual boost controller up here because we see big swings in baro during any drive up into the mountains. It would be easy to crank the boost while up in the mountains and forget to dial it back when we descend which could be quite hazardous to our engines health

I do think you have a boost leak BTW or more likely the gauge was off. IIRC you're making the correct amount of power for a bone stock IX (on that dyno at altitude), I doubt you'd hit those numbers at 13psi

 

I do think you have a boost leak BTW or more likely the gauge was off. IIRC you're making the correct amount of power for a bone stock IX (on that dyno at altitude), I doubt you'd hit those numbers at 13psi [/QUOTE]



i thought that the hp and torque numbers were alright (until i saw the boost graph), specially since they had a 2005 STI on there before my car and it had a full tbe and drop in filter and flash and i still had better numbers than the sti (227hp, not sure about torque), eventually they did a full tune on it then it had me beat at 255hp and 270torque.

 

Even temperature change will change your boost. So I would just get a MBC. I have one on my car. When I got my car flushed. It was supposed to be on 22Psi but my stock boost controller could not hold it at 22PSI. It would just get it up to 20 and just drop really fast to 16PSI. After the MBC I spike at 23 and drop to 19 at 7000 rpm. And just after putting my MBC on my car. Went from 13.5 @ 101mph to 12.7 @ 106 at LACR. I did have to re adjust the boost because when I got there I would spike at 19 PSI and go down to 15. And just to remind you this is at 2700ft

 

BRP, that isn't normal for Evos up here. Do you not know the name of the shop you went to? You gave us the crossroads, but why not the name of the shop? Was it Super Rupair, the Subie shop?

Anyway, be sure to study the potential mods before making your decision. You can make your IX very fast for very little money if you take the proper route. Just as an aside, Dynoflash will be coming to Colorado to do custom tunes (flashes) the first weekend of November. It will cost you $400 to get a full 2hr custom tune, and it's up to you if you want to utilize an MBC (my preference and suggestion) or rely on the ECU raise boost (can only do it with boost hose modifications, but it can be done).

 

no, the place was logic imports
thanks for all the replies

 

BRP,


Yes indeed the altitude and temp can make big changes in performance. Your spool up is slugish while in altitude. I happen to visit a friend (Evofunk) of mine from this forum there in Colorado Springs and I experienced myself the huge boost changes.

I even use the Gtech to meassure the performance numbers. You need to readjust your boost to compensate for altitude. Get With Warrtalon, he can give you good tips plus he lives there in Colorado.

Carlos

 

just something i just thought about (sorry forgot to mention this earlier, could this also be the gear that was used for the pulls. i have a 5 speed and my pulls were done on 3rd gear (tuner said he does all his dynos "2 gears from the top" so a 6speed would have dyno'd on 4th)