GT3076R 4agte help guys

[Poggy]

I figure if you're not just a dyno queen and have the dollars, go twincharged. More response, less peak hp but definitely a more driveable torque curve.

Considering a twinscroll exhaust housing, will def help with some of the lag

[adamaw11]

At the wheels and 23 psi, Its all about being able to make and hold peak torque at high rpm with a little motor. We rev mine to 9000 at the drags and makes peak torque at around 8300. The heads about as modified as you can go with a 4age with out going to oversize buckets and the cams are over 300 deg duration and over 10 mm lift. The trade of with very big cams is it makes an engine dull off boost as it bleeds of comp with all the overlap. Then a big turbo makes it worse again.

all interesting stuff, I guess all the headwork explains a lot.

It makes one wonder, how would the powerband differ if the same figure was achieved with more boost and less headwork. But there is probably a lot of variables that come in to play.

kw = (engine size x 100 x (1+ boost) x rpm) / 9402
where engine size is in litres, boost is in Bar or atm)
4A should be between 150Nm to 160Nm depending on how much you have improved or retained efficiency... harder at high boost

always fun these formulas. Are the cams and headwork taken into account by the rpm figure?

Can the static compression ratio be accounted for in the formula somehow? or does it not have significant effect on the max power output.

nah, dyno-dynamics dynos in oz (with the shootout mode etc) tend to read a bit lower than US or hub dynos... due to the way they ramp up, etc....

my point was just that with a good build, the flywheel should be well above 306kw

Yeah I'm convinced a hub dyno would always read higher than an on-the-rollers figure.

306kw is a lot in any case from 1.6L, no doubting that.

[oldcorollas]

always fun these formulas. Are the cams and headwork taken into account by the rpm figure?

Can the static compression ratio be accounted for in the formula somehow? or does it not have significant effect on the max power output.

No, it is just a really simple formula to weed out the dreamers

Basically, if you look at all pump petrol (up to 100 octane) piston engines as released from factory, from cars to supercars to bikes, the maximum torque per litre (apart from a select few) is 100Nm/L

Most bikes get up to that, most car engines are 90-95. some fezzas and the like are around 105Nm/L

Stock 4AG is about 150Nm/1.6L = 93.75... call it 94%VE
A well developed road engine NA will get around 160Nm ish.
Turbo engines have a hard time keeping the efficiency above 1bar, but with the right work, it can be done..
So using the assumption of sticking with pump fuel, and 95-100Nm/L, you can pretty much guess the power at peak torque (peak power will be at lower than 95-100Nm/L, as by sort of definition, the torque is falling away faster than power is being made at that point)
C16, methanol, E85 etc change the numbers, but with pump petrol, you are limited by the fuel, not by the engine (as such)

ie, the formula is nbot how much the engine WILL make, but how much it reasonably CAN make, if everything is good (but well developed race engines will make more)

[adamaw11]

ok, so I gather that the static compression ratio would make its difference to power output by increasing the VE

[oldcorollas]

Real VE? no, that is a measure of air consumed.
torque per litre? sure a bit, but will that take you from 95Nm to 105Nm/L?
the latest direct injection, high compression production engines are just getting over 100Nm/L now...

[DX20VT]

I figure if you're not just a dyno queen and have the dollars, go twincharged. More response, less peak hp but definitely a more driveable torque curve.

No good when we tried it, so much torque down low that it was uncontrollable,
could get 30psi @ 1200 rpm before we bleed it back down to 20,
and at higher rpm's the S/C just heated the air so much that there was no power.
Uncontrollable wheelspin until higher in the RPM's where it just had no power.

We replaced the s/c with a piece of U shaped pipe and run turbo only,
for day two of the event, and went from 30th to top 5 in one run.


and the near new Dyno Dynamic's here in town reads almost 50hp down on a 350hp car to the dynapak hub's up the road that 30psi 4agte and I use.

[Poggy]

anyone fiddled with divided turbine housings?

[oldcorollas]

DX, what boost were you running from the SC alone?

[DX20VT]

DX, what boost were you running from the SC alone?

Was on a 1GGZE, never ran it s/c only as the s/c's wont do the power we wanted alone.
Ran the Turbo into the S/C which was a standard 1GGZE running on std pulleys.


Built a tricky manifold for the twin scroll/twin entry T3 bushed turbo I ran for a start,

Then ran a BB GT3076R on same manifold,
BB spooled 100rpm (one hundred,) earlier max and made less top end,
so IMO if you can go twin scroll/twin entry, do it, good gains in response.

[abently]

anyone fiddled with divided turbine housings?

I didn't recommend you use a twin entry Turbine housing in my previous post just because I thought it would work better.

[the_random_hero]

No good when we tried it, so much torque down low that it was uncontrollable,
could get 30psi @ 1200 rpm before we bleed it back down to 20,
and at higher rpm's the S/C just heated the air so much that there was no power.
Uncontrollable wheelspin until higher in the RPM's where it just had no power.

We replaced the s/c with a piece of U shaped pipe and run turbo only,
for day two of the event, and went from 30th to top 5 in one run.


and the near new Dyno Dynamic's here in town reads almost 50hp down on a 350hp car to the dynapak hub's up the road that 30psi 4agte and I use.

Should have used a bigger pulley + kept electronic clutch. You're way out of operating efficiency at those boost levels (especially at higher rpm), blower should by bypassed and left to freewheel when the turbo comes on song.

[The Real Roadrunner]

anyone fiddled with divided turbine housings?

what size?
i dont believe they do one smaller than the .63 single so i doubt you would see a better spool up time, the mani would also have to be built properly to suit a split pulse inlet aswell.

cheers
linden

[Poggy]

what size?
i dont believe they do one smaller than the .63 single so i doubt you would see a better spool up time, the mani would also have to be built properly to suit a split pulse inlet aswell.

cheers
linden

I can get a .78, surely that would spool close to a .63? with better flow up high?

[abently]

This idea of spooling larger/mis-matched Turbo's has been a never ending quest by the human race itself since the invention of the first Turbo. There is nothing new and different you can try.

If you want to try the old school hack, mismatched (large) cold side and small hot side plus larger external gate, then do that because without setting up anti-lag or a complex twin-charge system there is no way you are going to achieve a result you'll be happy with.

[The Real Roadrunner]

I can get a .78, surely that would spool close to a .63? with better flow up high?

id still go for the .63 as i doubt the split pulse .78 would give much if any improvement in lag, it may provide better top end though.