VitTuned R&D -- Inside the D/I Pump

VitViper

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Part of our R&D for building out a MoTeC solution for this platform involves mapping & characterizing the D/I injectors (relatively easy) and the D/I fuel pump (much more complex). Here's a little sneak peak at the D/I pumps (yes plural).

Pictured is the non-Si D/I pump. It is a little different externally and internally vs the Si pump.
Honda Civic 10th gen VitTuned R&D -- Inside the D/I Pump IMG_2536

Next is the intake cam, that also drives the D/I pump via 4 lobes. This is also the non-Si cam.
Honda Civic 10th gen VitTuned R&D -- Inside the D/I Pump IMG_2535

The Si cam & pump are on order so I can take the pumps apart and compare them internally -- but so far what we believe is the Si pump will deliver a higher volume of fuel over the non-Si pump. The intake cam has a higher lobe profile for the D/I pump and should deliver more fuel.

No you cannot just swap the Si cam & D/I pump into a non-Si. There are software changes in how the pump is run (something we've already been digging into with @KTuner).
 

JDM_DOHC_SiR

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Thanks for the R&D on this topic @VitViper !!!
:headbang:
 

d1zguy

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Is the stock Pump limited to a certain amount of HP? Or doing this to be able to map MOTEC correctly?
 

dallasjhawk

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But... but... the SI is just a 1.5 EX-T with a tune! Right guys!?

:rolleyes1:
The most annoying argument ever..... when they would say, "ill just get a Sport 6MT and a tune and itll be just like the SI."
 


davemarco

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The most annoying argument ever..... when they would say, "ill just get a Sport 6MT and a tune and itll be just like the SI."
We already knew that the suspensions are like night and day. Now it seems like new subtle differences between the EX-T and the SI are being discovered all the time. It's like me saying that if I were to drop in the 2.0T motor from the Accord, that I'd have a Type R. Maybe if I spent the money to upgrade every little drivetrain and suspension part to match, then sure, I could potentially make my SI into something very close to a Type R. But by then, I could've just bought a damn Type R.

EDIT: I'm still not ruling out dropping in a 2.0T in the future though. :)
 

d1zguy

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The most annoying argument ever..... when they would say, "ill just get a Sport 6MT and a tune and itll be just like the SI."
For the everyday Joe it will be just like the SI. For the everyday drive straighline performance is what is most apparent. If you're pushing the limits of a EXT or SI on the street you're just asking for trouble.

But if you're Auto-x or tracking then yes a EXT will not just be like the SI but for everyday and 98% of the drivers a EXT with a tune can be just "like" an SI
 
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VitViper

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Is the stock Pump limited to a certain amount of HP? Or doing this to be able to map MOTEC correctly?
There are clear limits to the D/I system regardless of Si or not. This is part of what we have to do to get a D/I vehicle converted to our MoTeC solution -- and it is nice having details on both profiles, even if we start with the Si (and I mean, for anyone starting with an EXT, it's trivial to drop in the intake cam & D/I pump out of the Si once using a MoTeC... among other things).

8 injectors in the future?

:)
 

davemarco

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For the everyday Joe it will be just like the SI. For the everyday drive straighline performance is what is most apparent. If you're pushing the limits of a EXT or SI on the street you're just asking for trouble.

But if you're Auto-x or tracking then yes a EXT will not just be like the SI but for everyday and 98% of the drivers a EXT with a tune can be just "like" an SI
I am willing to concede your point on the comparison between the non-sport mode SI acceleration and throttle response, and a tuned EX-T. However, I can tell you that the difference in throttle response on the SI in Sport Mode vs Normal Mode is significant. Normal mode throttle, to me, feels like my old 2007 Sentra - slower and much less responsive to throttle inputs. You really need to step down to get it to wake up. By contrast, Sport Mode feels much closer to the feeling of an old school throttle; it's still drive by wire, but even gentle inputs really get a response.

I'd argue that even for non-track type weekend fun driving, the combo of the much more sensitive throttle and the drastically better handling create a differentiated experience over an EX-T with more boost.
 

360glitch

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I am willing to concede your point on the comparison between the non-sport mode SI acceleration and throttle response, and a tuned EX-T. However, I can tell you that the difference in throttle response on the SI in Sport Mode vs Normal Mode is significant. Normal mode throttle, to me, feels like my old 2007 Sentra - slower and much less responsive to throttle inputs. You really need to step down to get it to wake up. By contrast, Sport Mode feels much closer to the feeling of an old school throttle; it's still drive by wire, but even gentle inputs really get a response.

I'd argue that even for non-track type weekend fun driving, the combo of the much more sensitive throttle and the drastically better handling create a differentiated experience over an EX-T with more boost.
I won't pretend my Sport hatch is the Si hatchback that Honda did not build BUT throttle sensitivity can be adjusted any way you'd like with Ktuner. :thumbsup:

:topic:

For those more familiar with DI setups than myself, is duty cycle a good way to judge what a DI setup like this is capable of?
 


dc2turbo

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I won't pretend my Sport hatch is the Si hatchback that Honda did not build BUT throttle sensitivity can be adjusted any way you'd like with Ktuner. :thumbsup:

:topic:

For those more familiar with DI setups than myself, is duty cycle a good way to judge what a DI setup like this is capable of?


a video of evans talking about DI on the Cobalt
 
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360glitch

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VitViper

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Looks like you are on the the right track. I did some further research and found some information regarding the C7 Corvette DI system:

https://www.hptuners.com/forum/show...direct-injectors-C7-Corvette-LT1-supercharged
You can't actually throw out a fixed "duty cycle" for a D/I system, as the injection time will vary based on variables such as ignition timing (when you fire the spark plug) and start of injection for the fuel (SOI). Effectively you only have the intake & compression strokes to inject fuel AND you have to be done WELL before fire the spark plug (IE, you can't finish injecting fuel as you fire the spark plug for your power event) as the fuel needs time to tumble/mix. So effectively this gives you (360* - ignition_timing* - time_for_mix) injection time, also relative to engine speed (at low engine speeds you have way more time to inject fuel). With some trickery you can actually start your fuel injection event into the end of the exhaust stroke, depending on CAM timing you are using (for example on other platforms I'll injection 30-40* into the end of the exhaust stroke, giving me a lot more TIME to inject fuel).

If you ever get too close to the spark event, you risk misfires, detonation, etc. I've actually hit this limit on the Si already, so I have examples of what happens not only on the Si, but other platforms as well.

For your average consumer, right now, you're not going to get close to this limit.
 

360glitch

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You can't actually throw out a fixed "duty cycle" for a D/I system, as the injection time will vary based on variables such as ignition timing (when you fire the spark plug) and start of injection for the fuel (SOI). Effectively you only have the intake & compression strokes to inject fuel AND you have to be done WELL before fire the spark plug (IE, you can't finish injecting fuel as you fire the spark plug for your power event) as the fuel needs time to tumble/mix. So effectively this gives you (360* - ignition_timing* - time_for_mix) injection time, also relative to engine speed (at low engine speeds you have way more time to inject fuel). With some trickery you can actually start your fuel injection event into the end of the exhaust stroke, depending on CAM timing you are using (for example on other platforms I'll injection 30-40* into the end of the exhaust stroke, giving me a lot more TIME to inject fuel).

If you ever get too close to the spark event, you risk misfires, detonation, etc. I've actually hit this limit on the Si already, so I have examples of what happens not only on the Si, but other platforms as well.

For your average consumer, right now, you're not going to get close to this limit.
Thanks for the breakdown. Do you anticipate the fueling system to be a limiting factor for the inevitable stock location turbo upgrade options?
 

Shankmeyster

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So, the real question is, what kind of power limit can people realistically expect from the platform, even if they upgrade the turbo?
Sponsored

 


 


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