4500 RPM at 75 MPH?? (94 Prelude SI) - Honda Prelude Forum

LudemanDan · 05-15-2005, 05:56 PM

Hey,

I just got a 94 SI

and I hope there's something wrong with the tach. I had a 93 Prelude S before and it did about 3500 RPM at 75 or 80 MPH. I would expect the SI to have slightly higher gearing, not drastically lower!

When I wind it way up to shift the tach flies into the red really fast, even though the engine sounds like it's not there yet. This also makes me think (and hope!) that it might be reading too high.

If you can explain this to me, please do. I'm pretty sure the speedometer is accurate, because if I slow down to 65 everyone passes me.

-Dan

P.S. This car had an HKS Circle Earth groud wire system until right before I bought it. Maybe there's some electrical weirdness.

petern101 · 05-15-2005, 10:03 PM

nope my si is about that high..........iirc 80mph i'm hitting 4k though.......are you sure you are reading it correctly? tachs aren't the most precise things in the world either.........i use my safc to see my revs though......

did the guy before you change the tranny in anyway?

LudemanDan · 05-15-2005, 10:10 PM

Quote:

Originally Posted by petern101

iirc 80mph i'm hitting 4k though............did the guy before you change the tranny in anyway?

I'd be fine with 4k@80MPH - that would be only a little higher than my S, if I remember correctly. At 80 in this car I'd be closer to 5k. If I can believe the tach.

I don't think the dude changed the tranny, based on the fact that mods to this car are very few, and he didn't mention anything about it. Didn't exactly speak the best Engrish though...

I really want to believe the tach is wrong. It seems to fly up too fast. But I don't know how to refresh the wiring or recalibrate it.

Dan

EDIT: By the way, isn't your left front wheel on backwards?

TruNinja619 · 05-15-2005, 10:35 PM

Quote:

Originally Posted by LudemanDan

I'd be fine with 4k@80MPH - that would be only a little higher than my S, if I remember correctly. At 80 in this car I'd be closer to 5k. If I can believe the tach.

I don't think the dude changed the tranny, based on the fact that mods to this car are very few, and he didn't mention anything about it. Didn't exactly speak the best Engrish though...

I really want to believe the tach is wrong. It seems to fly up too fast. But I don't know how to refresh the wiring or recalibrate it.

Dan

EDIT: By the way, isn't your left front wheel on backwards?

I just noticed that too..

LudemanDan · 05-15-2005, 10:38 PM

I mean, wait, no... the wheel can't be on backwards. Rather, it's a right-side wheel, and you've got a left-side wheel on the right.

When I was looking at cars, I saw one with three right-side wheels and one left-side wheel, and I didn't buy it partly based on that.

petern101 · 05-16-2005, 12:20 AM

lol everyone always notices my rotation........i don't have directional tires so i don't just rotate back to forward (and vice versa)

hmm and onto the orignal thread subject.......that is really weird and i can't belive your tach could be that off, another speed i have memorized is 3k rpm@65mph@5th gear, looks like its time to buy a safc and really see if your tach is off......

LudemanDan · 05-16-2005, 12:43 AM

Yeah, that's what I'd expect. At 65 my car says I'm at about 4,000 RPM. It was about an hour drive home on the freeway after I bought the car and I just did the speed limit most of the way because I couldn't believe the tach. Although I really enjoyed kicking it down to fourth for uphills and feeling the pull...

Okay, how much is an SAFC, what does it stand for, what else does it do and most importantly, will it also read wrong if the problem originates with the sensor in the engine and not with my dash needle?

Dan

petern101 · 05-16-2005, 10:29 AM

if you know what a VAFC is then its kinda the same thing but for non-vtec motors.....

if not then this is what a SAFC basically is: it stands for "super air fuel controller" it controls the air/fuel mixture in your car, since stock engines generally run rich to prevent anything bad happening to your engine, you can "lean" out the mixture (put less fuel) and therefore gain a neglegent amount of hp for stock and maybe a lil more if you have mods,

the safc is directly connected after your ecu so i don't know for sure if a problematic sensor would matter.....but it is a much more precise measurement of rpms/throttle position

and i would also like to add you just don't buy it and it works, you have to tune your car

LudemanDan · 05-16-2005, 10:33 AM

Thanks, that's good to know. I don't think I'll be doing any fine-tuning, at least not during the school year. If all I need is rpm though, wouldn't it be just as effective to hook up a tach? (I mean, hook it up for a day, then when I'm sick of how rice it looks and I have my readings, take it out).

EDIT: petern101, you have a 94 SI too... next time you're on the freeway, if you remember, can you take a tach/speed reading at around 70-80 mph and report back? That might be a good indicator of whether I'm way off.

Thanks,

-Dan

homie_hoges · 05-16-2005, 05:22 PM

i have an SI and at 80 im only at 4 grand also

94ludefunk · 05-16-2005, 09:34 PM

I have an SI and my tach is off the same amount all the time. It doesn't jump or anything, it just reads high. I put a meter on my tach wire to check and set my idle. Everything reads perfect at that point. Anyone know if there is a fix for a faulty reading tach?

LudemanDan · 05-17-2005, 12:11 PM

Funny thing: I noticed my left front wheel is a right-side wheel too! The left fron and the right rear are switched around. I guess I was fast asleep when I bought the car this weekend and I just didn't notice.
I noticed when I looked at my own sig!

-Dan

MidNiteMysT · 05-18-2005, 10:06 PM

mine reads 4k at 80 too

pter · 05-19-2005, 10:45 AM

^ditto.

4k @ 80.

Maybe you have in 4th gean?

I did that once or twice.

MidNiteMysT · 05-19-2005, 12:16 PM

ok, so we have plently of confirmations that your tach is pretty off cuz everyone is reading 80 at 4k lol. i guess get some sort of other way to measure your tach like the safc. and btw, how do you tune your car? if you dont have this safc, can you tune the car too? i wanna get my car tuned, i just dont know how or where to take it.

MidNiteMysT · 05-19-2005, 05:22 PM

the only reason i can think up is when you get different size tires and rims, it throws off the tach and speedometer. since your car as the stock rims, check your tire size and tell us what it is. that may be the problem.

Si_g · 05-22-2005, 12:11 PM

at 80, i m at 3750...safc readings...more accurate...but on the tach...it shows a tad under 4

LudemanDan · 05-23-2005, 12:24 AM

I just got the car, and I'm so d@mn busy I don't have the chance to drive it or screw with it! Not to mention tune it. I hate school!
Anyway, the tire size is 205/55/15 on stock rims.
Where do you guys mount those Apex-I digital guages?

petern101 · 05-23-2005, 01:16 AM

well i guess i'll show mine.........i've been waiting to finish it off with some rubber molding around it to give it a "blended" look but just haven't gotten around to it

hmm just a regular interior

uber cool ricer placement!!!!

preludatic · 05-23-2005, 11:07 PM

or u could do this like i did