Roman's 4GR V6 Carina discussion thread

[Roman]

If this works I guess its a good incentive to port the heads at the same time.

Might just grab some spare heads from pick a part.

[kpr]

what about option  s ?   or  u ?

 

[Roman]

It really needs the 3/4 race cam for that to work.

I think ive only got a 9/16ths race came at the moment. 

[Dudley]

21 minutes ago, Roman said:

It really needs the 3/4 race cam for that to work.

I think ive only got a 9/16ths race came at the moment. 

Thank fuck your gibberish is finally starting to make sense

[shrike]

2 hours ago, Roman said:

If this works I guess its a good incentive to port the heads at the same time.

Might just grab some spare heads from pick a part.

Yeah means your intake isnt getting heatsoak and you can inject directly into the hot ports and hopefully have good atomisation.

Also means you dont have to worry about removing injectors if your swapping intakes etc

[Truenotch]

20 hours ago, kpr said:

what about option  s ?   or  u ?

 

 

19 hours ago, Dudley said:

Thank fuck your gibberish is finally starting to make sense

... Now I want to see six tiny IDAs mounted straight above the port split. 

[GARDRB]

3 hours ago, Truenotch said:

 

... Now I want to see six tiny IDAs mounted straight above the port split. 

IDF?

[GARDRB]

SUtututu

[Roman]

Once add a rail in, a lot of the high mount options are no good. 

There's not really enough space to poke them directly into the ports. 

I might just recycle my existing fuel rails and poke them in from the underside.

[yoeddynz]

What about sidefeed injectors. The micra ones I've used are so low profile. Would be easy to get a neat rail 3d printed accurate enough to take them (they seal with two O-rings. The injectors can be turned 360 degrees so the plugs can face any direction. Mine are only 130cc but I'm pretty sure theres a higher output version from something that the micra boys use when boosting. 

Standard rail here.. 

 

Edit : nissan GA16 injectors are 185cc. I could measure up a housing/injector height etc if it's of interest. 

[xsspeed]

does space/height not allow this stz? obv need to coord left and right banks 

[xsspeed]

same sort of thing Jenvey/OBX do on their VQ intakes

[Raizer]

10 hours ago, yoeddynz said:

What about sidefeed injectors. 

Mine are only 130cc but I'm pretty sure theres a higher output version 

Subaru has a range of sizes too, yellows are 440cc from memory.

[shrike]

8 hours ago, Raizer said:

Subaru has a range of sizes too, yellows are 440cc from memory.

The yellows can be decapped as well think they become 720cc from memory decapped

Blacktop 20v sidefeeds are 295cc

[Roman]

I tried but there's no room for that top style. 

There's no benefit to side feed compared to these insanely short top feed ones I've got anyway:



I'd rather have a worse injector position with a good runner shape, than vice versa. 

So will keep the taller runners. 

So long as this all fits I'm just going to do this and get it finalized. As otherwise I'll be spending 100 years gong around in circles.

 

 

 

 

My throttles turned up, everything looks good except for that the throttles are 50mm at entrance, 48mm plate, and 46mm at exit. 
Was hoping they were going to be the straight bore version damnit. 
Will see if I can whack them on the lathe and at least get the exit side out to 48mm. 
Will still be considerably better than previous setup, but not what I was hoping for.
 

[shrike]

16 minutes ago, Roman said:

 

My throttles turned up, everything looks good except for that the throttles are 50mm at entrance, 48mm plate, and 46mm at exit. 
Was hoping they were going to be the straight bore version damnit. 
Will see if I can whack them on the lathe and at least get the exit side out to 48mm. 
Will still be considerably better than previous setup, but not what I was hoping for.
 

Didn't the listing say 51mm ID? did they send you the wrong ones? 

[Roman]

That's just how it is, they would have just done a straight copy from the Jenvey kit which used the tapered bore.

Shit happens.

I guess in that config still good enough to make 350hp or whatever on a 350Z. 

But it should be easy enough to zing the exit side out on a lathe or cnc.

Saw this now, hah:



 

[shrike]

5 minutes ago, Roman said:

That's just how it is, they would have just done a straight copy from the Jenvey kit which used the tapered bore.

Shit happens.

I guess in that config still good enough to make 350hp or whatever on a 350Z. 

But it should be easy enough to zing the exit side out on a lathe or cnc.

Saw this now, hah:



 

Thats annoying, yeah if there is enough meat at the entrance to be 50mm getting the exit out to 48mm shouldn't be an issue as long as you can mount them in a lathe/Mill/CNC etc 

More progress is great though

[Roman]

On the Jenvey website it looks like they all use the same basic casting but then bore out the center differently, then fit a different sized plate. 

So could get carried away with it if want (I do not want) 

Will just see how it goes like this. 

Clock is ticking and things need to keep moving along.

[h4nd]

On 27/08/2025 at 01:10, Roman said:

Easiest way to have big hp per litre is to have the tiniest engine possible. 

AE 0.1CC Diesel Model Engine Micro 
https://www.youtube.com/watch?v=Ck4nID61rso&t=41s