kpr

@BiTurbo228  any chance you could do the long rod with the 404gram pistons?  sorry thread hijack.     I was also most worried about the stock pistons letting go. i think the long rod with lighter aftermarket pistons should be fairly happy.

interesting stuff.  

The pistons in my short rod engine  are 404 grams, inc pin and rings.   rods  around 465 grams.  

Long rod engine was stock pistons- 443 grams ,   rods  487 grams

guessing the long rod, even though pulling a few less g's would more likely to fly to bits due to the piston weight.

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. 

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?

Closed loop should only be there for a fine trim.  if isn't running right in open loop,  tune sucks or something has gone wrong.

As roman said.  too many variables to use egt to tune.  main use of egt probes is to see if you have a cylinder/s running different than the rest.   rather than having a wideband in each cylinder.

Just tune it right with wideband,  then run in "open loop"
 

On 07/06/2023 at 14:16, Rhyscar said:

Kinda makes you wonder if theres value in considering 2x different intake lengths?

Can be used to smooth out the bumps in power curve.  But having runners all the same length, at the ideal length. will get you best over all power by a little bit.     Also if your picky about your afr.  will be a bit all over the shop,

unless tune each cylinder

On 31/05/2023 at 18:13, shizzl said:

Righto, refitting the IACV on the 4age.

 

but where do these 5 ports go to?

I only have 2 water lines from the block that can tap into it.

I haven't play with stock stuff since forever ago,   but pretty sure the bigger 2 are are water.   rest are vac for various things.  idle up solenoids and the likes.  can block them off.

water at educated guess are far left and far right (bendy one)   but should be able to figure it out by blowing through them

Yeah most people don't try anything that long, due to fitment / too hard basket in a lot of engine bays.   But its really where the advantage is.    when it comes to getting it dyno tuned. Id suggest having a way to try 20-30mm either  way from that 320 length.  is enough to see the power curve move around, to see if your in the right place.   even though can shuffle it a bit with the vct , there still a litte bit to be had getting it bang on. 

If going to make a plenum for it. make it big as possible. same deal with feed pipe.

Yeah kinda re the skunk2 manifold,    the runner length thing works just the same on turbo stuff though.   It keeps coming back to the packaging thing and being a diddle to make.  shiny parts sell. 

one word ->  packaging

they will be aiming for the 3rd harmonic (itb's, the skunk2 maybe even 4th)     im aiming for the 2nd, which is stronger  = more power

tapered is said to accelerate the air.  maybe.    but are also losses in the pipe, so need to go bigger further from head to keep flow the same as.    real world isn't much effective length difference with taper, unless is way too much. or turns into a massive bell mouth, which will act like the pipe ends part way down the bellmouth into the runner, rather than the face.  in your case yeah i would taper out soon as get past the throttle plate.

Example of engine not caring too much if runners are too big;  The runners on the manifold i made are 2.25"  tube.    think its 53 or 54mm id.  half way around the bend it starts tapering down to the port.  so yeah its big.  bigger than the rbc intake and huge compared to the stock k24 manifold.   but still gains power right down at 4000rpm.  close to 10% at that point,  so not a small gain either.

Another example. The only place my 4age with 52mm throttles  drops below a stock engine is under 2000rpm.

Yup, thats the same inlet test i was referring to.   

Have you looked into s65 bmw throttles?  they are 52mm, spacing should be pretty close for k series.  the also have an oval outlet  similar shape to the port.   Have a separate dbw module  that can be used if wanted to go that way. but is known to crap out. 

I'd  probably target  8000rpm  maybe a touch under for your intake runner length.   about 320mm from port face should get you ballpark.    you want to  get the intake tuning right where the engine naturally wants to make peak power.  will make more power and fatten it up that way.  rather than kinda trying to force it to make more power right up top. like your current intake looks to be doing.    The VCT  (cam timing)  is also your friend here.  you can use it to hang onto the power past peak a bit longer.   If do everything right it should at least match the power it has now right up top 8500- 9k and make a bunch more 7500- 8000rpm plus more through the mid range 

The runner length on the manifold in video is around the 350mm mark, as was targeting bit lower rpm. 

Tuned a  1.5jz  with all the good bits on it the other day.  had those xpert injectors in it. maybe the 1350cc version, still a decap'd bosch either way.     was happily making over 400kw, no drama tuning it. 

you can also get the genuine 7 hole bosch injectors which are 980cc.  if dont want a modified injector

looking at your thread you have something like below.  and are thinking of dropping smaller after the 2.5" collector?

This is what i was meaning. angle straight down to 2" or so  where all 4 pipes collect.    The big straight through is key to making it work.  think of the exhaust ending after them.   what you do after isn't so important.  long as the pipe size is big enough not  restrict airflow.   merging into a single 2.5" probably fine in your case.   but you cant make it too big. just makes it harder to cut the noise down.   all the power is in the headers and the section before the first reso's

run the biggest glass pack straight through muffler /resos  you can fit for the  first mufflers.  put the chambered ones at the back

sizes yeh you can drop down smaller, but need to do it at the merge.   then go back out kinda like a megaphone setup.  if you do it right and place  said above mufflers in right place.  will gain  power off the bottom. 

1 hour ago, xsspeed said:

would be interesting to see if you could, I'm guessing either the cranks are mounted higher in a 4gr or the piston compression height is significantly different between the two (or both) to account for such stroke difference. solution is only a custom set of rods away if need be

probably just the usual shorter block height on the 4gr,   usually a toyota / most manufacturers move. save some material cost and make engine bit shorter.    so yeah  longer rods  would be needed.  probably giving a rod ratio well over 2.    bigger bore, bigger valves bit more capacity.  probably blow the budget, but would be pretty cool if the crank did swap over

2gr with 4gr  crank.  

Nar sorry, ones ive been using were bran new.  ( they are about 220 on amayama)  
yeah the small gear. it kinda looks like its backwards when its in the right way

Ive pulled one of those (vvti pulley) apart a million times.   pretty basic. but can put the together backwards hah.     only thing i suggest doing is sitting it on the cam and making sure it freely rotates through tis whole travel. there isn't really anything that locates them central,  if get them a little off can bind up at at one end of the travel.   I usually put it on the cam and rotate it back and forward nipping up the bolts. 

Valve to valve isn't an issue in my case either with wide angle head.   piston to valve = yes.       The exhaust cam timing is not so much that it can be off and work.  it needs to be right  and  when its right, its pretty happy to work across the whole rev range.  when its off it kinda sucks almost everywhere

If you wanted to try something in the meantime,  you could take the spacers out of the plenum.  Have some thick head flanges cut to space the manifold out at the head end, lengthening the intake runner.   Maybe a couple at 25mm  so can stack them see what works best.  I'm guessing around 50mm would do the trick. Maybe could get them cut from something for some thermal insulation at the same time.  

runner diameter being a bit oversized  isn't actually much of an issue.  unless its way oversized.  
length is probably an issue though. 

you can see its doing something weird on the dyno sheet, which is most likely the intake runner length.    looks like its wanting to work at 8500. which makes the dip at 7500.    if the runners were a bit longer (most likely factory length)   so it was tuned for 7800-8000rpm  would  make more power.   its something that can be shuffled with the cam timing to a point also. your tuner probably should have already tried that though.

Ideally get those itb's on and make the intake runners way longer.   nothing off the shelf will get you there either due to fitment issues, or too hard to make.