Roman's 4GR V6 Carina discussion thread

[Roman]

They're PA12 nylon. 

Ideally would have a radius there, but modelling program was being a dick about it.
If it starts to crack there I'll lay carbon sleeve over it like my other ones. 

However, with an e-throttle manifold and vertically oriented throttles. There's actually very little load on these. 
The throttles being a single piece ties it all together and add strength.

Where as with a cable pull manifold you have to make them really strong, to resist cable force from pedal.
Especially like 4AGE throttles where each individual throttle wants to move relative to the next. Each one tries to twist away from the others. 
 

[Willdat?]

Where did you outsource the printing to? (Sorry if you mentioned it already). I've used JLCPCB a few times as I like the online quote function which allows me to tyre kick without wasting a real persons time.

[BlownCorona]

can you not just replace the studs for bolts?
though looking at your engine mount plan, lifting the motor probably wont be too much of a drama. 

[Roman]

On 02/07/2023 at 15:32, Willdat? said:

Where did you outsource the printing to? 

Weerg.com

[Roman]

6 hours ago, BlownCorona said:

can you not just replace the studs for bolts?
though looking at your engine mount plan, lifting the motor probably wont be too much of a drama. 

Yeah ive had it in and out now a bunch of times while trying to make it fit better. Doesnt need to lift up very high. Probably wont need to on the other side where theres no steering column. I can live with that! 

Ive now got something that has pretty good clearance everywhere. But ive chopped and changed this a million times so its a bit of a mess. 

So I might redo it with some fresh bits when funds allow. Has been sort of fun and sort of frustrating. My plan to keep all the runners on a flat plane went right out the window. Just not enough space to the strut tower and chassis rail.

I think i will restart with a different approach. Start at the collector end and work back to the motor.

These are within 40mm of each other though which is pretty sweet. (So around 5% variation in length) 

[Willdat?]

52 minutes ago, Roman said:

Weerg.com

Oh my, so many options. Definitely not aroused...

[anglia4]

I'm pleased to see you removed the "maybe" from the title 

[kpr]

Guess there are 2 different ways of thinking. 

Treat like  2  3 cylinder engines   -  merge collector   cone up to 3"    into some big reso's  then merge into a singe 3"  after them

Attempt to get some secondary tuning from the 2 pipes after the primary's, keeping them smaller,  2"  or so  into a 2nd merge,  cone out into 3.5"  into a big single reso.   drop back to 3" after said reso. 

Either way i think your just under 2"  or 2"  "pinch point" after the merge sounds about right.   

Also the pipes after the primary collector should be even length, to stop it sounding like balls.  guessing you already come to that conclusion though. 

How long are your primary tubes going to be?

 

[Truenotch]

10 hours ago, Roman said:

I'm not sure if there's any useful tuned stuff happening in the 2-1 part of a 6-2-1 setup. 

Suurely there's something useful happening there, but the merge location might come down to packaging in the Carina?

Here's a handy video to illustrate what an IS250 engine sounds like at half of your target RPM (still way nicer than a VQ): 

 

[Roman]

Yeah i will definitely have the pipes merge before any mufflers etc. Try get the higher pitched sound from it. 

Im not really sure what length to aim for, for the 3-1s. Can go as long as I like really.

Current length with no collector was 640mm give or take.

Ive got heaps of room once im past the steering column. Since theres only 3 exhaust events instead of 4, id expect a longer pipe needed for same tuned length compared to a 4 cyl. Unless the scavenging effect is each runner scavenging itself. In which case the same length.

That noise from the car above does absolutely nothing for me. Ive never been huge on v6s. 

Buuutttt throw some doorty intake noises into the mix and its acceptable, even with pooey rpm limit:

https://youtu.be/1zQAPDmGZrg

With a few thousand more rpm than that, now were getting somewhere! 

 

[HighLUX]

Can you measure the spacing of the block engine mount studs/bolt holes for me plz @Roman

[Roman]

13 hours ago, kpr said:

Either way i think your just under 2"  or 2"  "pinch point" after the merge sounds about right. 

Completely off topic to anything and possibly not useful information. (Since when has that ever stopped me)
I measured the cross sectional area of the collector at a whole lot of points through it.

Then added cross sectional area of other known bits to show a map of whole exhaust.
The cross sectional area stays exactly the same as the runner until a point where it near instantly blows up to the cross section of all 3 pipes. 
Then tapers down from there, then flares up again.




The point in the collector where there's the big spike upwards, is here.  



It seems you cant do much to change how big or quick that spike is, except for by merging more cyls together or vice versa.
However changing the collector angle changes how quickly it ramps back down to normal cross sectional area. 

I found a picture of the Alfa 155 DTM engine / it's exhaust manifolds. 
Doesnt look like anything especially magical going on there. Beefy diameter runners though
Runner lengths seem fairly long considering it's a 14,000rpm motor. Meaning way longer than that is probably good for mine.

[Roman]

4 hours ago, HighLUX said:

Can you measure the spacing of the block engine mount studs/bolt holes for me plz @Roman

Sure. They're different left to right. 

This is the drivers side of the block, looking at the face that bolts to the block.




Then this is the passenger side, looking at the face that bolts to the block.

[kpr]

those bolts holding headers on that alfa  thing look like they would ruin your life

Yeah unsure if the sudden change in cross section is a good thing or bad thing.     but can say the cobys i tested with the ugly big open collector made less power everywhere.  other being not very even, primary lengths were similar to my headers. so the the collector was the main difference.     soo seems like at least cutting down that space maybe a good thing. or possible just the shape?
 If it was some way possible to eliminate said change in area would primary length be irrelevant.
 Also  any sudden change in cross sectional area i have tested in various places in exhaust, has always  given negative or at least no gains.  where as changing the same transition to a diverging cone has given some power gain. 

 

 

[Mitch.W]

No clue on the exhaust setup but this is a goood sounding 350z, it makes pretty happy noises at the end doing skids 

 

[shrike]

Do you need to have the oil distribution block on the sump to be that size? Could you make it lager off to one side and tap for fittings off to the side instead of have it out the front? Or do you need the lines to be from the front?

[Rhyscar]

Great work getting primaries to fit better. One things I found is not all bends are created equal. Adrenalin R bring in their bends which have a smaller CLR than the autobend/S&T ones so worth checking out the different options. But yeah cutting and shutting them like you have gets it done, I'm always surprised at how far a small amount gets you on the end of a 180deg bend. 

 

Collectors - don't bother with bandsaw its very hard to clamp/hold it on the angle required for the cut. Just Sketch out what you want, holesaw the big end/drill roughly where small end is (with some room for error) and free-hand the rest with a grinder. Yup it sucks but at least all your fingers will be intact. 

 

As for secondary length - have you seen this book? Can borrow my copy if you want. It talks about how secondary lengths don't matter so much, as overall length stays the same in 4-1 vs 4-2-1 applications. Reckons 4-2-1 is normally only used as a function of packaging, not performance. The book also has a section on V6 header and exhaust design which I skipped over as it was talking about a triumph V6.... and talks about exhaust sizing/lots of things you're looking at. 

 

[deankdx]

how deep is the oil pan, is there any reason you can't do an in sump pan oil filter?(other than losing some volume and being a pain to change) 

makes oil changes with filter a bit more annoying but it might package well. or a recessed oil filter but would need modding the sump pan in same spot

just some oddball idea that popped in My head. 

[Roman]

Yeah i thought of that. But too much of a pain.

Although probably not an issue if the engine wont last the length of an oil change interval 

[Roman]

1 hour ago, shrike said:

Do you need to have the oil distribution block on the sump to be that size? Could you make it lager off to one side and tap for fittings off to the side instead of have it out the front? Or do you need the lines to be from the front?

It can go anywhere, its just if i were to internally drill from the front then thats how it needs to go.

 

Im leaning towards a small pair of 180 deg pipes inside rather than drilling from the front. So fittings thread in from the top.