My OHC VTEC - Lowered, Stiffened, FFE'd and Now with ITBs!!

[pranavt]

Originally Posted by Shan2nu

Oh ok. So what is the expected output of your engine gonna be like? It would be nice to see a dyno graph once the mods are done.

Shan2nu

Apart from a flat torque curve right upto the redline, I'm not predicting anything else. I am definitely going to get it dynoed whenever the ECU is tuned upto my satisfaction.

[ported_head]

Originally Posted by pranavt

Unlike the usual 4 hole injectors, these are 12 hole injectors. Therefore, the drops of fuel are smaller than what you have with the usual injectors. This means that the fuel atomises better even at lower air velocities. The ports are circular btw, and the 42mm ports can make a maximum of around 50-55 bhp per cylinder.

The 600RR has 12 hole injectors for both primary and secondary stages. But the spray pattern is radically different. So spray size may not be the only criteria for atomisation. Of course the constraints in a motorcycle engine are far higher, due to much higher rpms. Manufacturers also have emission constraints and driveability limitations ( throttle response, etc.)

Also volumetric efficiency is not affected by size of the TB alone. Everything from the intake geometry, to the mixture strength to nature of flow contribute to it.
I have no experience with running such a setup on another vehicle, so it may very well be that engines are a lot more forgiving than they seem to be.

Originally Posted by pranavt

Crome doesn't. Neither does any other offering for OBD1 Honda ECUs as far as I know. Doesn't it depend on the ECU though?

Yeah it would. I kept thinking of Jitu's Hondata when I was talking about Nitroxx's car.

Originally Posted by pranavt

The distance between the valve head to various things like injectors, butterfly, velocity stacks determine the optimum powerband, which I guess you already know. However, mounting them ITBs directly to the engine, or that close to the engine would mean that the engine would have to run at insane RPMs to make all that power. And we're talking about a D15 engine which would pretty much run out of breath at around 8.5k, valvetrain upgrades included.

I was quoting MPower when I replied. I was giving him an idea of the runner lengths in the 600cc motorcycles. I was by no means implying that you should run similar runner lengths on your 7000 rpm engine.

[Mpower]

To get the full effect of ITB, it has to be mounted motorcycle style close to the engine.

Powerband depends on distance from valve seat to vel stack. Injector and TB dont matter.

Since you are using batch injectors and retuning the AFR map, I think you'll be OK.

BTW, what was the need to change the injectors. (unless you are thinking turbos)

[pranavt]

Originally Posted by Mpower

To get the full effect of ITB, it has to be mounted motorcycle style close to the engine.

Absolutely. But the low and mid-range will be affected, by upto 1/3 of the power that can be made with the right lengths. You can build 400 bhp turbocharged monsters, but you still have to drive on the same old Mumbai/Indian roads. Hopefully we will one day have a place to exploit everything our cars are capable of. Until then, compromises are the order of the day.

Powerband depends on distance from valve seat to vel stack. Injector and TB dont matter.

Not directly. But injectors closer to the ports will mean less time for the fuel to atomise at higher rpms/velocities, and consequently, higher emissions at the cost of actual power. Same with the TB. Lengths, tapers and diameters decide the velocity of the air flowing into the ports.

There's no getting away from the fact that you are always making a compromise in one/two of the 3 powerbands to get optimum power in the desired band, whether it's turbos, exhausts, cams or ITBs. Sadly, as a daily-driven car in Mumbai, the choice is quite obvious.

BTW, what was the need to change the injectors. (unless you are thinking turbos)

They came with the ITBs. Hmmm....

[pranavt]

I don't know if I should keep bumping up the thread for trivial updates or not as I don't see a lot of interest in the thread. Let me know if I should keep posting or just stick to major updates.

Anyways, here goes. Had a chance to drive the car more than a few metres today. This is on the stock OBD2B OHC ECU with the IACV disconnected, so the Check Engine Light was on, as expected. I am going to be plugging in the standalone system tomorrow which has a better basemap.

Initial observations:

• Idling surges. Will be fixed as a suitable IACV is on the way. After that, I can close the tiny holes that are present on the ITBs and are used on the bike with its own FIW system.
• AFRs are off, towards the richer side. At WOT, the AFR is around 10. At part throttle, it hovers around 12. Will be fixed once I start tuning the ECU with my wideband tomorrow.
• Even through all this, once the car goes over around 2k rpm, the throttle response is much much better. With a proper tune, it will only get better.
• Need more negative pressure/vacuum. Brake pedal is way too hard. Bigger holes for vacuum are needed. Will need to remove the ITBs for that, sadly. And more scrapes and cuts in the hand will follow :(. Should be done in an afternoon though.
• The sound. Barring the continuous sucking noise that's made because of the tiny idling holes, the engine note is

Let me know if I should keep posting these updates. And where's doomsday? If someone is in contact with him, could they please tell him to drop-by in this thread? Thanks!

[salilpawar1]

No interest in this thread? You are kidding, aren't you? For instance, I have been following this thread from day one but haven't posted anything in this thread before this. Does that mean I am not interested?

Keep up the good work and the DIY spirit!

[Mpower]

Originally Posted by pranavt

I

• Idling surges. Will be fixed as a suitable IACV is on the way. After that, I can close the tiny holes that are present on the ITBs and are used on the bike with its own FIW system.
• Need more negative pressure/vacuum. Brake pedal is way too hard. Bigger holes for vacuum are needed. Will need to remove the ITBs for that, sadly. And more scrapes and cuts in the hand will follow :(. Should be done in an afternoon though!

You can try using a electric vacuum pump that is found on diesel cars. If you can find one that is.

Are there 4 ICVs ...one for each TB?

[ported_head]

Must be a fast idle wax solenoid for idle control. Can you not try and use that for idle adjustment? But, hmmm.....you will lose AC.

[pranavt]

Originally Posted by Mpower

[/list]You can try using a electric vacuum pump that is found on diesel cars. If you can find one that is.

Are there 4 ICVs ...one for each TB?

It's a completely mechanical system with a Fast Idle Wax Pellet unit.

Thermostat - Wikipedia, the free encyclopedia

I've removed the wax pellet system and am using the idle screw. The screw pivots the idle adjustment which can also be pivoted by the FIWP unit. The idling system is made up of 4 tiny bypass holes which can then be blocked by 4 pistons through the idling system. A picture will be able to explain this more coherently than me though, so here's two

Hmm, hadn't heard of a vacuum pump before. Sounds useful. What does it run off?

@ported_head: The IACV is on the way, so it's not a problem. I never wanted to use this system anyways, having to use it just because the IACV wasn't procured on time.

[Mpower]

Some are electric, some are mechanical either sits on the v-belt or attached to the alternator. A good diesel mechanic can fix up something for you.

[pranavt]

Still waiting for the damn IACV. In the meanwhile, managed drilling bigger holes myself and put bigger fittings for vacuum which should be good to go. Completely removed the original idling system as it was pointless and made adjustments for the IACV. Here's a few pics, including the latest pics of the engine bay, just finished doing it a day ago...









Oh, btw. Something else too. Fun fun fun

[ankitahuja]

Ah the package has arrived haan, thank god, even my wait is going to be over soon then
The other package should reach you today or maximum by tomorrow! Where are the gears and when/where is the IACV coming from??

[pranavt]

Single gear, on the camshaft

IACV was bought seperately, before all this stuff actually. The shipper forgot to ship it, so taking its own sweet time now.

[nitrous]

Congratulations on the new cam. You lucky VTEC-ers!

[pranavt]

The IACV finally arrived yesterday, 1 1/2 months after I ordered it. One more big change as well. Have to do a bit of wiring from the Harness > ECU side, which I'll do tomorrow, after which I expect all CEL codes to go away without any compromises or hacks. ECU tuning will start tomorrow as h/w shops are closed today and I need a few fittings for the IACV and stuff. Have been pushed to the limits of my patience and it's nice to see everything hopefully coming together now. Then I can start planning the next stage of mods