Roman's 4GR V6 Carina discussion thread

[Roman]

Actually, I dont know. 

It doesnt say on their website at all. 

that would make sense though.

[ajg193]

You'd hope so, otherwise your big cam would only be like a Stage 1.2 4K 1/8th race cam

[kpr]

doubt the 1nz cams were 264 @ 1mm. thats pretty massive.  would be in the 300's  @ 0.1mm.   but yeah depends on the cam manufacturer  what the "advertised"  is measured at.  sometime 0.1mm or 0.3mm on jap stuff.   so possibly the 264's where at 0.3mm.  

But yeah, still can be vastly different that's why the 1mm numbers are a bit more relevant.   the 4gr cams must have a slow ramp to keep the valve train happy.  for them to be only 207/205 @ 1mm and  263/262 at 0.1mm.   other cams in the 260's  will be 220-230 at 1mm. 

short version get them big cams @Roman

[ajg193]

https://kelfordcams.com/product/toyota-2gr-fe-performance-cams-4/

interesting how aftermarket cams get off the ground later but ramp up faster. Shirley those extra ~10 deg would barely be worth the cost?

 

Edit: Looks like the kelford NA option is quite possibly just OEM pattern?

[kpr]

other than more stress on the valvetrain,   more jam without any of the side effects of longer duration cam.    so still runs like a nana car.
but yeh not much of an upgrade if want to make decent power

[Roman]

Cam duration specs are definitely interesting (by which I mean, confusing!) 

So I thought Kelford makes the biggest duration cams, they list a 280 deg with 12.7mm lift. 
However Cat Cams do a 295 deg, with 13mm lift. 
Sounds great! 

Well, comparing the lift at 1mm is interesting because they're near identical on the intake side, and the Kelford exhaust side has more duration. 
Which is likely what would be good for these tiny exhaust valves/ports.




Despite 15 more degrees at 0.1mm, there's only 3 degrees difference at 1mm (which realistically, you're not flowing anything before that) 

So I guess the 295s would ramp down onto the seat nicer, but, effectively the same apart from 0.7mm extra lift.
Which is nothing to sneeze at, but I think the cat cams are reduced base circle regrinds. With some mixed  reviews on the net. 
Kelfords might be too, I'm not sure. But if they're cost neutral I'd rather go with Kelford option.

[kpr]

would be interesting to see the whole curve on them.  if the kelfords  open the valve faster to the first mm. do they continue on accelerating the valve faster, getting to higher lift faster?

 

This is an interesting pic that shows the numbers shown, only tell a small part of the story.    left is a 318/11mm   right is a 320/10.8mm    pretty much same on paper with the advertised measurements.  not so much when looking at them.

 

[Roman]

Yeah thats interesting! 
Like if there was a measurement for "Duration at 70% or greater lift" 
the numbers would be way different between those two.

Although, probably dont need to make things even more complicated haha.

[ajg193]

Which one of those two cams actually worked better?

At what point do the gains from extra area under the curve get outweighed by harsher dynamics on the valvetrain

[kpr]

The one on left worked bit better.   but bad example of what would actually work best.  as both kinda sucked for the application. too much duration.

Can only go so much duration till it turns your engine into a turd.   im running a 304/300  (262/258 at 1mm)  combo.    the 318/320 takes a massive hit in the bottom end for only little numbers up top

Yep, kinda in the cam manufacturers hands on that one. too aggressive will just start breaking stuff.

 

[BiTurbo228]

There was a chappy called oldtuckunder in the Triumph world who did a fair bit of investigation of various aftermarket cams for the 2.5 OHC before he passed away. His main conclusion was that the advertised specifications of a cam (not just duration, but also the four timing numbers) didn't match anything at all on the actual cam grinds. He reckoned their main goal was to sound flashy so they sold cams, and make it so if someone went to a cam grinder and asked them to grind those specs they'd end up with scrap. Not sure if that's something peculiar to Triumph/UK cam manufacturers or whether they're all at it.

His setup was pretty simple. Popped the cam on a lathe and attached a dial indicator and degree wheel, then turned the cam through its rotation and marked lift every degree or so. Not really accurate enough to reproduce a cam from (there's odd stuff that happens with where the radius of the dial indicator nose sits relative to the angle), but enough to get a decent comparison between cams. It's simple enough to do with a flat surface and vee blocks as well. I did it to demonstrate what everyone knew already: that the Rover 2600 in the SD1 was detuned with a weedy little bumpstick by comparing it to the M20B25.

 

[Truenotch]

11 hours ago, BiTurbo228 said:

There was a chappy called oldtuckunder in the Triumph world who did a fair bit of investigation of various aftermarket cams for the 2.5 OHC before he passed away. His main conclusion was that the advertised specifications of a cam (not just duration, but also the four timing numbers) didn't match anything at all on the actual cam grinds. He reckoned their main goal was to sound flashy so they sold cams, and make it so if someone went to a cam grinder and asked them to grind those specs they'd end up with scrap. Not sure if that's something peculiar to Triumph/UK cam manufacturers or whether they're all at it.

His setup was pretty simple. Popped the cam on a lathe and attached a dial indicator and degree wheel, then turned the cam through its rotation and marked lift every degree or so. Not really accurate enough to reproduce a cam from (there's odd stuff that happens with where the radius of the dial indicator nose sits relative to the angle), but enough to get a decent comparison between cams. It's simple enough to do with a flat surface and vee blocks as well. I did it to demonstrate what everyone knew already: that the Rover 2600 in the SD1 was detuned with a weedy little bumpstick by comparing it to the M20B25.

 

Interesting! I wonder if his numbers would have been much different if he measured at the lifter instead of on a lathe? 

[BiTurbo228]

I seem to remember applying valve lift via rocker ratio and it got even weirder, what with it changing over the course of their motion due to where they contact the valve moving around relative to the pivot point (both the follower and the rocker finger). I don't think it ended up changing things enough to align with the advertised specs, but I'm not sure he actually measured valve movement directly.

The thread's here if people fancy a look.

Edit: found the thread on rocker ratios too

[VitesseEFI]

Some interesting work by Alan there. Thanks for finding the links. I’m reminded that I was planning to revisit this using an actual engine, measuring actual valve movement, all relative to crank degrees, with a selection of cams…. I’ve shot myself in the foot by selling the block I was going to use though…. (idiot!)

[Rhyscar]

On 18/08/2023 at 21:02, Roman said:

Anyway, thinking something that looks like this. Bong shaped intake, paying some homage to my West Auckland cultural heritage. 
Maybe I could make some trumpets out of 8% woodys cans.

 

Nothing of value to add here other than encouraging you to do this silly idea. We tried a woodstock/diesel powered 4age once. Was a bit low on compression and had a headgasket issue. 7%RON was obviously no good. 8% or 11% Cody's would have done the trick I'm sure. 

 

[Truenotch]

19 hours ago, Rhyscar said:

 

Nothing of value to add here other than encouraging you to do this silly idea. We tried a woodstock/diesel powered 4age once. Was a bit low on compression and had a headgasket issue. 7%RON was obviously no good. 8% or 11% Cody's would have done the trick I'm sure. 

 

 

Goes good.

[Rhyscar]

Wow I can't believe that's still on youtube... 

[BlownCorona]

I spoke to my friend RE roller throttles. i tried to convince him to sign up and post here lol

his gut feeling was that a lot of money was spent on peoples opinions and the performance gains from rollers was never really proven (potentially if actually validated these days would show they gain nothing much). He did say that they had a massively positive response from one of the drivers who just loved the response of the double rollers, but when they really drilled down to the bottom of it, it turned out that what he actually liked and misattributed to the throttle design was the lighter throttle spring they had. 

[Roman]

Hey, thanks for following up! 

I cant remember the exact details or where I saw it. 
But I remember someone put a car on the dyno where they could hold the load steady. 
So they ran a butterfly throttle setup, then took the butterflies out and reran for zero difference (just controlling engine speed with dyno) 

Like has been evident from a lot of KPRs testing, there seems to be littler harm in just oversizing the intake diameter. 
Seems like the intake is most sensitive to changes at both ends (and length) but not much of the middle area seems to make too much difference, within reason.

However - Barrels are still cool, nice and compact, and potentially easy enough to manufacture for a one off experiment.

I found the picture of the barrel setup in the V8 race engine. 

[BlownCorona]

doing something because its cool is always valid.