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Discussion Starter #1
I took my 92 SE-R out the Wednesday night drags at LACR in Palmdale. Even though I won 7 of my 10 races mostly against Honda's I lost to and modded Integra twice and to a Celica once. But my best time was a 16.980 at 83 mph. LACR is at about 2500' and my car usually is at sea level. It seemed to have less power than I normally get. I was running 205x60x14 street Yoko's and had a bunch of **** (Maybe 100lbs worth) in the trunk because we weren't sure about leaving lying in the pits. The only thing I can think that may have affected it was the altitude. I met up with a couple of other SE-R drivers and they were consitently in the low 15's.
I was disappointed.

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Art R.
1992 Sentra SE-R
SCCA Solo II Driver
Cal Club #823 E Stock
 

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Discussion Starter #3
Is there a way to reset the ECU for altitude?
 

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Discussion Starter #4
Ok, I just talked to a friend of mine who is an automotive engineer.
First he said that the SE-R ECU is mapped for 93 octane and I run 92. He estimated .3 sec loss if you use 89 octane so I figure I lost a tenth there.

Altitude affects performance you lose 3.5% of your horsepower for every 1000 feet in elevation and .2-.3 sec in the 1/4. So at 2500 ft this would convert to .5-.75 sec.

Plus the tires I was running 205x60x14 would effect the gear ratio and account for 4-5% in my 1/4 mile time.

I am going to run at Carlsbad on my BFG racing tires which are 205x55x14 see what happens there.

[This message has been edited by Trys_Hard (edited 05-17-2001).]
 

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Actually I believe that the elevation is about I think its higher then 2300 I remember when I was driving up there it felt like I dropped a cylinder, I managed to bust a 13.6 at 8 pounds of boost, on streets though, still couldnt get traction. But the elevation does seem to effect it alot.

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Mike.
Turbo Classic, T3/T04e Tial 35mm ".65Bar" Blitz BOV, Custom piping griffen intercooler Core with HK$ EndTanks,custom manifold, 370cc injectors, paxton fpr, Eibach Sportlines, everything else was stolen,:( Pectel coming up bigger Injectors and custom fuel rail. DAMN VILLIANS.
 
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I didn't think the SE-R ECU is mapped for 93 octane......yours is stock, right?
 

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<font face="Verdana, Arial" size="2">Originally posted by Limited Slip:
FI cars shouldnt be hindered *much* by elevation changes</font>
Why? NHRA Pro Stock cars -- which are normally aspirated like F1 but make gobs more horsepower than an F1 car -- slow down by .4-.5 seconds at altitude. If it doesn't have a blower, it's going to slow down considerably.

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'93 Sentra SE-R, daily driver and track/autox toy
 

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Actualy he is wrong....the classic and I think all sr20's are 'mapped' for 87. One thing about the old engine it was designed for low octane fuel. Check your owners manual thats the first place to look. Like my friends old maxima or now his type R it says 92 or better no matter what. The sr20 is an old dog so it was designed for low grade. I put 89 just because I like to be nice to the engine and the tad bit better gas mileage I get out of it.

But then the engine isnt 'mapped' really for any octane of gas. Its a hot-wire MAF system. It takes the air readings and the o2 readings and determines the gas to send. As for octane mapping...it doesnt know the difference. If it sees knock(which is one of things you put higher octane in to stop) it retards the timing. Its not a honda that has a hard set MAP for certain octane with certain levels of air pressure.

Kick your timing up to 17 and run 92 octane and that should help a bit. I dont do it cause I dont like depending on premium...and its too expensive. How much you want to bet people will start droping their timing down so they can go back to mid or low grade this summer.
 

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<font face="Verdana, Arial" size="2">Originally posted by slowSER:
Why? NHRA Pro Stock cars -- which are normally aspirated like F1 but make gobs more horsepower than an F1 car -- slow down by .4-.5 seconds at altitude. If it doesn't have a blower, it's going to slow down considerably.

</font>
thats what i said.
Pro Stock = NA
 

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Discussion Starter #11
<font face="Verdana, Arial" size="2">Originally posted by mrwillis5050:
I didn't think the SE-R ECU is mapped for 93 octane......yours is stock, right?</font>
Yes it is.

But I do know that altitude does effect performance in our cars. After 10 runs at LACR I had a good feel for how the car was performing.

Just before I got home I wound it out to third and the power was back. It was very apparent that the car was running a lot stronger.

Is there anything that you can adjust for this?
 

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Discussion Starter #12
<font face="Verdana, Arial" size="2">Originally posted by Storm88000:
What were your 60' foot times? They are crucial. </font>
My 60' times were consitently in the 2.5 sec range one run was a 2.4.
 

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Hello, nice to hear someone whine about a couple of thousand feet and their cars performance. I would love to take my car to a dyno before each of my upgrades, but it would only make me cry. Why? you ask? well Colorado springs is 1000 feet higher than the "mile High" city of Denver, putting us at 6400' elevation, and yes, it does affect your cars performance, at the math in one of the above posts, take off 22%. I know this in real life because I have driven cars from here to Cali and there is a noticeable difference, and no, FI does not compensate in the fact you won't lose horse power, it only leans the gas out so you don't burn rich. So in conclusion, YES, it does affect your horsepower.


High and missing some ponies,

Dave
92NX, AEBS headers, UDP (2), Pop intake, Dynomax muffler.
 

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Discussion Starter #14
I just race at the Lone Pine Time Trials this weekend at 3800'. It was really noticable this time on an Solo I type course.
There were 2 other classic SE-R's out there, one owned by a gal named Christine and the other was a Black Classic but very modified.
I think he probably rally's the car because he had rally lights on the front bumper also!
He sure drove it like it was a rally car, I was working when he ran in Street Modified and he was fun to watch sliding that car all over the place. I was never introduced to him so I'll have to look up his name when I get the results of the weekend. Oh by the way, my car won the STS class on both days. On Sat my co-driver won and I won on Sunday.
 

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kool bro, I don't know too much about that type of racing but it's good that an sr20 won in your class

<font face="Verdana, Arial" size="2">Originally posted by Trys_Hard:
I just race at the Lone Pine Time Trials this weekend at 3800'. It was really noticable this time on an Solo I type course.
There were 2 other classic SE-R's out there, one owned by a gal named Christine and the other was a Black Classic but very modified.
I think he probably rally's the car because he had rally lights on the front bumper also!
He sure drove it like it was a rally car, I was working when he ran in Street Modified and he was fun to watch sliding that car all over the place. I was never introduced to him so I'll have to look up his name when I get the results of the weekend. Oh by the way, my car won the STS class on both days. On Sat my co-driver won and I won on Sunday.
</font>


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92'xe/w-primera swap
working on built motor for some NOZ
 
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