Roman's 4GR V6 Carina discussion thread

[h4nd]

On 27/12/2025 at 10:39, Roman said:

 

 a sample from 21 - 22s

... 40-41s

 

 

[Roman]

Download this and then watch the vid on youtube, and it's easier to see in hz in realtime.

https://chromewebstore.google.com/detail/youtube-musical-spectrum/ddpceafiohdlkiemibjgplcicblnfggi

Press ctrl alt G to bring it up, then click on the music notes and it'll show it as Hz instead

[VitesseEFI]

Presume the white one is the sound you’re aiming for? Sounds pretty angry - almost like a V12…..

[h4nd]

.

[h4nd]

On 28/12/2025 at 22:23, Roman said:

Download this and then watch the vid on youtube, and it's easier to see in hz in realtime.

https://chromewebstore.google.com/detail/youtube-musical-spectrum/ddpceafiohdlkiemibjgplcicblnfggi

Press ctrl alt G to bring it up, then click on the music notes and it'll show it as Hz instead

I should have recorded at 2ms/div, to get a whole 2 rotations sweep (4T ~13ms). Then I suspect you'd be able to see the primary exhaust peaks, and the offset between the groups of 3. It's more difficult to infer with the reflection noise here.

Maybe 5ms, to get a repeat or two.

[VitesseEFI]

Yeah, reckon the horses are awake….. Probably several fields further away now too 😀

Nice positive update. Good to see you have the throttle control sorted. That exhaust merge does indeed look like a sod to weld! Suffering for your art….

On the injectors, what fuel pressure are you running and could you not increase it to extend your injector range?

Interesting about the gearbox and the bellhousing/front cover.  I’ve been wondering similar about my MX5 conversion where the front section has the bell cut off and an adapter ring welded on to take a Triumph bell. It’s not so much a shifting problem (the homemade shift mech would probably get the blame anyway), more that both gearboxes I’ve tried have been disappointingly noisy (grizzling like a well-used Triumph box in all indirect gears) even though both boxes have seemed decent. Mine is supported all the way around so it would have to be welding distortion.

Jacking yours up in the centre has got to be worth a try. Is it a big effort to add per support if this proves to be the problem?

[Roman]

Adding a support will be fairly easy. 
I've currently just got a big hole exposing the flywheel down low, so really need to do something about that either way.
I could probably chop up the rear part of a factory sump to make a brace.

These gearboxes have this reverse pivot lever thingy, that just sits in place until you push a pin through from the outside of the casing. 
So the ways to hold it in place until the pin is in. Are either with a rubber band, or some very thick grease. 
Then pray that you dont knock it off when you push the pin through.
If you knock it off, you have to redo the casing sealant. so its a pain. 
I've ended up using a few rubberbands to hold it in place.
So its possible that this is relevant. 
When I put the old casing back on the front, I didnt have the reverse lever in place or rubber bands on it.
So I've got a few things to test and eliminate as variables.

The welding wasnt done right up against the face of the gearbox that the bearings etc mount into. There was still say 20mm of more of the original bellhousing there. 
But, yeah. It's possible. Not sure how to fix it if that's the problem though. 
Maybe I should have had it bolted to the other half of the gearbox casing while it was welded.
It's also maybe possible that my input shaft is bottoming out into the rear of the crank or something.

I've got a few methodical steps to test. 
But the main problem is that you can move the lever through all the gears. 
Then sometimes it will get to a gear and only shift half way, but it the lever is stuck solid. 
If you pull it back out of gear then in again, sometimes that will now work. Or need to select another gear then back to it.

My fuel pressure is already quite high, think its 53psi. So turns the 300cc injectors into 330cc compared to running them at 40ish.
So I think I definitely do need something extra. 

 

[shrike]

2 hours ago, Roman said:

Adding a support will be fairly easy. 
I've currently just got a big hole exposing the flywheel down low, so really need to do something about that either way.
I could probably chop up the rear part of a factory sump to make a brace.

These gearboxes have this reverse pivot lever thingy, that just sits in place until you push a pin through from the outside of the casing. 
So the ways to hold it in place until the pin is in. Are either with a rubber band, or some very thick grease. 
Then pray that you dont knock it off when you push the pin through.
If you knock it off, you have to redo the casing sealant. so its a pain. 
I've ended up using a few rubberbands to hold it in place.
So its possible that this is relevant. 
When I put the old casing back on the front, I didnt have the reverse lever in place or rubber bands on it.
So I've got a few things to test and eliminate as variables.

The welding wasnt done right up against the face of the gearbox that the bearings etc mount into. There was still say 20mm of more of the original bellhousing there. 
But, yeah. It's possible. Not sure how to fix it if that's the problem though. 
Maybe I should have had it bolted to the other half of the gearbox casing while it was welded.
It's also maybe possible that my input shaft is bottoming out into the rear of the crank or something.

I've got a few methodical steps to test. 
But the main problem is that you can move the lever through all the gears. 
Then sometimes it will get to a gear and only shift half way, but it the lever is stuck solid. 
If you pull it back out of gear then in again, sometimes that will now work. Or need to select another gear then back to it.

My fuel pressure is already quite high, think its 53psi. So turns the 300cc injectors into 330cc compared to running them at 40ish.
So I think I definitely do need something extra. 

 

Are Evo X factory injectors an option? (I know they are different plugs potentially) seems a few V10 BMW upgraded injectors list EVO X (4B11) as also being compatible. Along with Porsche 911 and AMG merc etc 

EVO X injectors are 550cc factory and id say a few should float around 2nd hand if people have upgraded etc (you would obviously need 2 sets) 

 

[kpr]

Assume you probably dont want to buy 6x new injectors at about $100 each.       But if you do  get some 980's  in there -  0 280 158 040
being able to  move the injection window around with the lower duty, actually makes more power on my engine over 9k.     

 

 

 

[Roman]

I think the injectors in there at the moment are "3/4 length" (ish) but I need the long pintle.
Those 980s would be sweet but looks like a shorter body length, which is problematic for my fuel rail situation.
It looks like these might be a good option. 

Maybe I'll just buy one for starters as a test fit.

[mjrstar]

This v6 with itbs has a bit of an e-type soundtrack to it which I kinda dig.

https://youtu.be/WRwFSo3dgYQ?si=uHTEiFD0VmoU2NSP

[HumberSS]

You are a fucking geek and I enjoy that. 

[HumberSS]

2 hours ago, mjrstar said:

This v6 with itbs has a bit of an e-type soundtrack to it which I kinda dig.

https://youtu.be/WRwFSo3dgYQ?si=uHTEiFD0VmoU2NSP

vid of it from induction end 

 

[Roman]

Is the bro using marshmallows for engine mounts? haha
Looks like hes close to yanking an ignition lead off. 

Yeah that car sounds pretty good

[yoeddynz]

Mazda KLs sound fucking cool - especially with itbs.  I'm sure I've shared this here before but this one sounds great and its pretty damn rapid for a front tugger (but for the bloody music overlay) 

 

[Roman]

Since my old 2-1 section was laying there, I welded a flange on right at the join. Then mounted it backwards onto my new 2-1 so its an X pipe of sorts. 

This is definitely the winner so far, no mufflers yet though. But a reasonable difference in sound.

Still sounds grot but it's heading in the right direction. Will definitely do X pipe.
 

Compared to how it started 
 

 

[xsspeed]

i like the lack of mechanical sympathy, barely ignited, foot flat and hold

[yoeddynz]

Several dogs barked in the distance.

[Roman]

8 minutes ago, xsspeed said:

i like the lack of mechanical sympathy, barely ignited, foot flat and hold

I need to keep it pinned get some good data from it

That's my story and I'm sticking to it 

But yep its working at the right frequencies now. So mufflers can hopefully do the right job from here.

With X pipe:



Compared to drags: 

[VitesseEFI]

13 hours ago, yoeddynz said:

Several dogs barked in the distance.

And horses jumped fences….😛