Keef's Car Thread | Wheels on the Bus | 09/08/23

[Eric.]

I can never find the graph anymore, but back when Hondata just sold a reflash (that is, one generic tune or everyone, just set up for an Injen CAI, DC Header, and exhaust), there was a dyno graph comparison showing 25ft-lb gains on a bone stock Si. All from lowering VTEC, really. And that makes sense. You're always going to make the most torque below 5250rpm, it'll never peak above that. So lower the spot where the car begins to make power and, voila!, big increase in peak torque.

Also, with the way hondata's tunes work, I don't instantly hit VTEC any time I'm above 4250rpm. There's a separate table that determines that based on manifold pressure (i.e, your throttle position). I can drive past the crossover in normal driving (though that's starting to get loud, so I don't...) and not hit VTEC, though its very close to it. There's a second point where no matter what it will switch to VTEC, like the stock tune would. I don't remember what that point is, its near the stock 5800rpm changeover though.


eSZee: My MR2 has a system called T-VIS (Toyota Variable Intake System maybe?) where the intake manifold has a secondary set of runners that open above 4400ish rpm when it needs to breathe more, but allows for more torque below that RPM then they're closed. Apparently it has a cool sound to it, but since I've still got the stock 10ft of intake tubing...you'd never know it had anything.

 

[eSZee]

Yeah, same I have pretty much. If the 2ndary runners are left open, there is a power drop in the lower rpm range. With it always closed, there is a significant power drop as you head towards the redline.

 

[Eric.]

Which car are you talking about?

 

[Keef]

...there was a dyno graph comparison showing 25ft-lb gains on a bone stock Si. All from lowering VTEC, really. And that makes sense. You're always going to make the most torque below 5250rpm, it'll never peak above that. So lower the spot where the car begins to make power and, voila!, big increase in peak torque.

That's not always true. Where the torque peak is just depends on the engine design. You'll recall 5252 being the rpm at which the torque and horsepower curves cross. That's the solution you use to convert the two.

Also, with the way hondata's tunes work, I don't instantly hit VTEC any time I'm above 4250rpm. There's a separate table that determines that based on manifold pressure (i.e, your throttle position). I can drive past the crossover in normal driving (though that's starting to get loud, so I don't...) and not hit VTEC, though its very close to it. There's a second point where no matter what it will switch to VTEC, like the stock tune would. I don't remember what that point is, its near the stock 5800rpm changeover though.

That's some crazy technobabble you're on now. Back in my day, D- and B-series VTEC was oil pressure activated, i.e. a function of rpm. The only thing the computer did was tell the solenoid to open at a certain rpm, but it didn't keep track of all that other stuff.

What are you two on about with Toyotas?

The last-gen Celica GT-S had some sort of variable valve timing that sounded like VTEC and produced similar results but worked very differently. It may have been more advanced, but it didn't produce the same gains.

 

[eSZee]

I'm talking about the vq30dek from the 2000-2001 maxima. Put it in a 95-96 and you've got 10-40whp gains from the switchover til redline.
As for what Erick said, the car stays on the low cam below the 4500rpm switch and on the high cam from the 5800rpm switch. Between 4500 and 5800, throttle position dictates which cam is used.

 

[Eric.]

That's not always true. Where the torque peak is just depends on the engine design. You'll recall 5252 being the rpm at which the torque and horsepower curves cross. That's the solution you use to convert the two.

I believe it is...Find any dyno graph where torque exceeds horsepower above 5252.

What are you two on about with Toyotas?

The last-gen Celica GT-S had some sort of variable valve timing that sounded like VTEC and produced similar results but worked very differently. It may have been more advanced, but it didn't produce the same gains.

The last gen Celica basically tried to have VTEC (VVT-i?). I'd have to look up exactly how it worked, but I think it may have only opened up more intake valves/held them open longer? i-VTEC (intelligent VTEC - the ones with electronic technobabble as you put it), works on intake and exhaust valves and..well, other things.

The only thing I was on about with Toyotas is that the 4A-GE in my MR2 has eight total runners in the intake manifold. Four of them are always open. One more per cylinder opens above ~4400rpm, for more breathing. Below 4400rpm it is more efficient to be sucking air through just one runner per cylinder.


And what eSZee said about how my VTEC works is correct (though its 4250rpm )

 

[ROAD_DOGG33J]

I believe it is...Find any dyno graph where torque exceeds horsepower above 5252.

That doesn't necessarily mean that the torque doesn't increase. Look at an S2000 graph.

 

[Eric.]

Hmmm....nevermind.

 

[Thatman]

*snip*
What's wrong with them?

At least you can remove the air pump on your S4 without messing them up. I can't take mine off because it operates the aux ports, unless I want to use electronic actuation which is complicated.

So yeah, I mean I know its not the air pump since my friend 88 GXL works fine and when he dynoed he got 146.

 

[Keef]

That doesn't necessarily mean that the torque doesn't increase. Look at an S2000 graph.

Even engines without tricky torque-boosters like VTEC that were designed for high rpm operation. Hell, F1 engines probably idle at 5000 rpm. Sport bike engines are hardly usable at that rpm. It just depends on the design of the engine - it just so happens that for the sake of reliability, driveability, and efficiency, that most street car engines produce torque at much lower rpm.

The last gen Celica basically tried to have VTEC (VVT-i?). I'd have to look up exactly how it worked, but I think it may have only opened up more intake valves/held them open longer? i-VTEC (intelligent VTEC - the ones with electronic technobabble as you put it), works on intake and exhaust valves and..well, other things.

Toyota's system was variable valve timing, as the name suggests. The cams are adjustable. That's not how VTEC works because VTEC is not variable valve timing, and I don't even know if you can call it variable lift and duration because nothing is "variable". It's a hydromechanical system with two possible results - either the rocker arms are unlocked and the two small cam lobes operate their valves, or the rocker arms are locked and the big cam lobe operates both valves with more lift and duration. Honda's system is totally unique as far as I know, and very different from other manufacturers' VVT systems.

Thatman, to embed a youtube video you put what is after the "=" sign in the video's URL between the
Looks like one of those actuators is working, or doing something at least.

 

[Thatman]

Looks like one of those actuators is working, or doing something at least.

Ah thanks, but either way, the action that we should see there is the ports going DOWN not out. (and in the s5 case it may be up) But either way on my friends they do go down just fine. So thats where I attributed a 20ish horsepower difference when we dynoed our cars. But Im hoping someone will want my car and I can find a turbo version for less then $4000.

 

[Keef]

As I posted in the Latest Purchase thread, I snagged myself some Stance GR+ Pro coilovers tonight, plus 4 more Buddy Club lug lug nuts to complete the set of 20, and a K&N air filter because that's about as far as I'll bother going with intake mods since they don't do anything. My paper filter is looking ugly anyway.

So, Friday, Saturday? I don't know lol. I'm just sad I won't be able to put them on over spring break!

 

[Keef]

 

[Eric.]

Shame on you. I was expecting pics on the car.

 

[Keef]

They look a lot better by themselves than the car will with them on!

 

[Perfect Balance]

Put them on. Then pics.

 

[WeinerSchnitzel]

Those look nice! Can't wait to see them on your car.

 

[nk4e]

How much?

 

[Rotary Junkie]

Those look nice! Can't wait to see them on your car.

In before Keef sets them on the roof and takes pics.

 

[eSZee]

Sweet! My buddy just got a set of stance coilovers for his STI. We should be putting them on in the next couple of weeks.

 

[Keef]

How much?

Not too much.

Anyways, while hunting for a brake problem I ran across something that should have been painfully obvious weeks ago: bubbles where the master cylinder and reservoir meet. It seems I've sprung a leak...

I can't fix it tomorrow because I have to order the part, so it won't be until during the week or next weekend when I get a chance. Ugh, working on cars during school.

 

[Eric.]

Yep. I hate trying to balance school, two jobs, and wrench time (plus friend's schedules to get those jobs done).

Oh, and talking about the weather in my thread...It snowed enough to accumulate on the cars at work tonight. I'm driving around with Star Specs on. Ugh. Will be a nice cold day of finishing the MR2 brakes.

 

[Keef]

Found a bad one!

I've been checking each piston in the front calipers...press the pedal, one comes out, close it, clamp it...press the pedal, another one comes out, close it, clamp it...press the pedal, third one....

Yeah. Currently on my seventh piston. It's the first one that created pressure on the pedal, it has a tiny tear in the boot with white crusties inside, and I can't close it by hand.

Luckily Autozone sells Duralast copies, and they're even stamped "MAZDA" on the front like the stock ones. Only $94 each, $42 after core charge. Judging by prices of other parts I'd have figured these would be $500 each.

So here's my list:

1 master cylinder - $60
2 calipers - $42 each
1 set of stainless lines - Iono, like $120
1 or 2 or 3 bottles of RBF600 fluid

Hopefully there's no fluid in my booster!

 

[Eric.]

Pfft, just put some Wilwoods on it.

 

[Keef]

They don't make anything for my car -_-.

But Endless does!

EDIT: Ordered some Russell stainless lines, now it's time to order my other parts and find some RBF600.

 

[Keef]

Found some moonshine:

 

[Keef]

Car is out of commission for a bit. What was supposed to be a simply brake part swap and bleed has turned into a major fiasco thanks to faulty parts and God's own air pockets, so I'll be limping it to work a mile away to trade with dad for a few days.

 

[eSZee]

Are you planning or replacing the perches on the coilovers or are you gonna stick with the stockers? Upon closer inspection we realized perches are soft aluminum just like they use on ksports and all those other cheap brands and the wrench will screw them up in no time.

 

[Keef]

Are you planning or replacing the perches on the coilovers or are you gonna stick with the stockers? Upon closer inspection we realized perches are soft aluminum just like they use on ksports and all those other cheap brands and the wrench will screw them up in no time.

You're talking about the collars? They're perfectly strong billet, not soft cast aluminum like my calipers, for instance. I've yet to understand how people can destroy their collars with spanner wrenches anyway. One problem most people run into is the collars seizing on the threads, but that's why you disassemble them and wash the useful threads with anti-seize like I did. It will gather dust and dirt but it will keep the black-oxide threads from rusting and I won't have to struggle to adjust them in the future, which I'll probably only do once or twice more anyway.

Last weekend I went through two remanufactured brake master cylinders, both of which leaked at the base of my stock reservoir, so I now have a brand new assembly waiting to go in the car. I also received my Russell stainless lines and a few speed bleeders to make fluid maintenance easier in the future, especially because I'll be switching to RBF600 once I get this system in good running order.

Also this...

 

[eSZee]

Yes, the collars/perches. They are universal, aluminum collars used across the STANCE range.
We just didn't think they were that "cheap" compared to the rest of the components.


edit

He's either gonna make a new set of collars or a better set of wrenches. The worry is about them stripping after a few uses.