Roman's 4GR V6 Carina discussion thread

[Rhyscar]

@keltik yes and no, there is still an increased differential pressure (very small pascal numbers - but it exists) across the filter when 'sucking' air through a filter harder - although you're right in that service interval will be lessened the hard it works.. 

 

So for my airbox, I worked out factory filter was 44,000mm2 or something like that, so that became my minimal filter area required. Given you'll probably run a K&N or higher efficiency (generally meaning bigger appetures), this can probably account for some of the increased breathing the engine will want to do at more HP. I think the filters I ended up with were 38,000mm2, so I used two to make sure there was more than I needed. 

Perhaps you could work out the airflow volume at factory engine peak HP and then your estimated airflow at 10000rpm. Essentially, you want the airflow rate/mm2 to be at least the same, or better under your max HP operating condition. 

 

In the past, I've also used a panel filter in a rounded orientation to increase filter area. Might be an idea to squeeze a bigger filter in. With 3d printing everything, the possibilities are endless, so maybe don't restrict yourself to making mounting it flat. 

 

 

[Truenotch]

@Roman can you run a bigger air filter on an angle to get more filter area? If you lean your filter almost flat, you could almost get a square filter in that's the same width as your mock up. Green Brothers Racing do it this way, but I can't find a photo of the inside of their air boxes...

So here's an example of how the herb growers do it while they're saving up to pay for a Green Brothers 13BPP and sequential: 

 

[Roman]

Yeah these filters are not a solid plastic housing, its like silicone rubber or something. 
So could definitely make it curved if that works better or whatever. 
It's easy to test though, even without a dyno - Two back to back runs, with the filter in or out. (and/or airbox off) 

It looks like I might need to rethink my plans anyway.
I have just been doing some bonnet measurements and it's a lot worse than I would have hoped. 
I've just cut the center brace out of a spare bonnet, so max clearance possible.
Even with that gone there's only about 20mm clearance from the top of my lower manifold part to the underside of bonnet at the worst point. 

So I might need to run some  side feed inlets on it instead of coming straight out the front.

Or make it a lot wider at the pinch point, so cross sectional area is still alright. 

[Roman]

The longer filter is only 85mm tall instead of 100mm, so might be the better pick given the constraints.

[shrike]

3 minutes ago, Roman said:

Open Trumpets out of the bonnet is the only option 

Just need to find my 9" grinder

This is the way :p 

[Roman]

Ahhh might work with the longer filter, and then just sculpt around whatever obstacle is under it.

[Truenotch]

23 minutes ago, shrike said:

This is the way 😛

Torana / Carina. Same thing.
 

 

[Truenotch]

Is there anything stopping you from doing this? 

 

[Roman]

Yeah I can probably figure out something like that. 

Just having another look at the engine bay, there's another simple way to improve the situation whether it ends up front feed or side feed which will unshroud the throttles a bit. 

Which is redo the fuel rails. I thought they would look cool with the swoopy sort of design but they look a bit strange when on the motor.

I could easily remake them so they are only as low as the flange that mounts them to the throttles. Then I can run a wider airbox all the way back. Then they will be hidden so wont matter what they look like. So will just make them easier to machine this time. 

[Truenotch]

That seems logical.

There's nothing stopping you from doing a @Rhyscar and leaving the final design of the airbox to the end of the project. Obviously it'd be cool to make progress on something now, but you can leave this bridge to burn at a later date. Filters only matter once you're driving . 

[Rhyscar]

Making airbox interfere with the bonnet (with some foam for max comfort) for max clearance might be an option. You'd be surprise how much the bonnet will move at the centre/base. 

 

Also another idea from the brains trust - if you go wide to feed as much air as possible you could use internal vanes (kinda like canards) to help feed air towards the trumpet. 

The airbox is the hardest part of anything like this!! But you're making awesome progress - I haven't found a way to make the process not suck, so just keep moving forward. 

[Rhyscar]

and you've probably already seen this, but for others' reference. Here's some awesome science on trumpet clearance by @kpr

 

[Roman]

21 minutes ago, Truenotch said:

That seems logical.

There's nothing stopping you from doing a @Rhyscar and leaving the final design of the airbox to the end of the project. Obviously it'd be cool to make progress on something now, but you can leave this bridge to burn at a later date. Filters only matter once you're driving . 

Yep 100%, can keep plodding along with this while also getting other things sorted. Still got a to-do list that's a mile long to get car sorted for cert. 
My metal printed linkages parts to hopefully finalize my ethrottle setup should be arriving in a few days hopefully. 
That's the main thing I need done, to carry on tuning the car.
I've had a fairly bodgey way of mounting the e-throttle motors currently (cable ties were involved) and this means the PID isnt great. B theres a little bit of slop in everything, it tends to undershoot or overshoot by a bit.
Once everything is solidly sorted, hopefully the bank to bank targets will be really good.

I've also been thinking that may some of my wacky fuel results, like wanting 85% VE at 5% throttle at 800rpm. 
Is due to lack of a fuel damper.
I originally designed the rails to accomodate these, but with the final version they slightly hit on the lip on the firewall. 
So might be a reason to redo the rails anyway. 
For the next iteration I'll put everything that needs to be machined on the same plane. Injector holes and the fuel hose fitting all facing the same way, and on the opposite side of a flat base.

It will give a whole heap more space around the throttles.

[yoeddynz]

2 hours ago, Truenotch said:

here's an example of how the herb growers do it while they're saving up to pay for a Green Brothers 13BPP and sequential

A bit presumptive thinking that all herb growers are rotary fan bois.  Some of them have probably matured to more exotic tastes 🧑‍🎓

[Roman]

Like Meth? 

[yoeddynz]

16 minutes ago, Roman said:

fuel damper

IIRC a decent length of rubber hose feeding the rails can be quite an effective damper.

[Rhyscar]

Another idea - trumpets don't need to be cylindrical. Not sure if KPR has tested any like this, but it could help give more clearance on top outside edge of trumpet to airbox. You probably don't have much room to play with, but might be able to make it 5-10mm better at a push. 

 

Example from motorbike stuff;

 

[Truenotch]

1 hour ago, yoeddynz said:

A bit presumptive thinking that all herb growers are rotary fan bois.  Some of them have probably matured to more exotic tastes 🧑‍🎓

Sure. 

[GARDRB]

Hahaha, can you imagine Bemrose growing weed. His wife does social media for the police and the guy can't shut up, so he would tell everyone.


Shaker scoop is the answer. Turn the airbox into the bonnet.

[Truenotch]

4 minutes ago, GARDRB said:

Hahaha, can you imagine Bemrose growing weed.

I was referring to his fans rather than the man himself. He wouldn't joke about such things. 

 

We should get back on topic...