hokiruu

iTrader: (19)

Last but not least also T3 SS and not BB. Not the biggest factor, but yours is all of the slower spool criteria versus all of the fastest on his.

It would be interesting however to see the difference between an SXE versus EFR and similar size all other variables being equal.

Shamsiel

Not true. The reason why a SS spools slower than a TS is because the AR is not equal. For example a 1.0 t4 open and a 1.0 t4 twin. The twinscroll spools like a .50 t4 open and should make around the peak power of a .80 t4 open. like @letsgetthisdone said it was a stock block. So the timing was conservative, as well as it spooling slower than a 2.4. The car spooled nearly 700rpm sooner on my 93 pump tune because it made 100whp less and he didn't have to worry as much about the rods saying bye bye. I'd like to see what it would do on a built 2.0 maxed out and full send on timing, I'm sure it would spool nearly Identical to the 7670. Also a twinscroll helps more keeping the car in boost between shifts than anything else.

LetsGetThisDone

iTrader: (1)

It's not because of unequal AR, it's due to less efficiency. A proper sized T4 twinscroll housing spools faster and makes more or same power as properly sized open housing.

hokiruu

iTrader: (19)

What's not true?

LetsGetThisDone

iTrader: (1)

This is wrong/not true. Twin scroll has a large effect on efficiency by pairing cylinders.

hokiruu

iTrader: (19)

Definitely, it's been proven many a time on this forum and others for over a decade. I was asking @Shamsiel what they were saying was "not true."

eflove

Some video of the car from this weekend
Starts at 2:36.50

Shamsiel

So can you explain to me why all the high HP drag builds use open t4 housings? If TS housings make uncompromised power then why are they not using them? It’s because it’s a trade of, you don’t get the peak hp you would get running a TS housing of the same size. There’s about an 20% difference in peak efficiency up top.

Construct

iTrader: (4)

Can I suggest you start a separate thread?

Would be a shame to see this great build thread derailed with an unrelated argument.

Construct

iTrader: (4)

Looks great out there. I see you're not afraid of a little slip angle out there.

Would you be willing to share some details of your suspension setup? Spring rates, front/rear bars, and alignment? What diffs are you running?

Dallas J

iTrader: (1)

Looks pretty good out there, very transitiony. I'm gonna guess it has a bit of mid corner push but entry braking and exit throttle is pretty loose? Im guessing the rear rates are pretty mild in this case.

Abacus

iTrader: (9)

That looked like a blast! Nice driving Jenson!

May want to consider the proven Racefab oil pan or a clone If track days are going to be the norm with a big tire/aero.

eflove

I think you nailed it pretty perfectly. Push mid corner in a steady state so using a bid lift or trail brake to put it on the nose. It was much looser without the junkyard trunk/wing. Spring rates and shocks are very mild as listed below. I didn't chase my tail too much as the Achillies 123s tires seemed like the main handling issue.

"May want to consider the proven Racefab oil pan or a clone If track days are going to be the norm with a big tire/aero."
100% I have a moroso/ams pan, and over fill the oil 1/2qt. I log oil pressure pretty closely with the motec dash. Never saw less than 25lbs oil pressure (still scares me). The main saving grace I think is the terrible, low grip Achillies tires I had to run. I looked around for a racefab pan when for a bit but it was a difficult item to get ahold of. This is NOT a track car for me but I do want a street car I can take to a track once a year. I will be adding a accusump and staying away from big grippy slicks.

The current setup is as follows.
255's Achillies 123s 220TW
Ohlins road and track. As delivered spring rates. Not swapped front and rear.
WhiteLine 26mm bars front and rear. Rear on middle setting. WL end links.
WL ball joints and tie rod ends up front and offset bushings in rear toe arm.
Stock bushings otherwise (class rules) These move quite a bit when strapping the car to the trailer.
Front C2.8 T0 Rear C2.3 T1mm in per side.
Restacked stock rear diff
English racing ACD tune. Settled on the tarmac setting to tame the oversteer.
Stoptech rotors, carbotech ap10/12 combo. The brakes boiled the paint off the calipers every 2 laps. To be fair they never failed just would degrade. That's saying something for 160mph stops.
I fully understand this is not optimized but this is quite comfortable on the street. First laps I have turned in the car so wanted a baseline before adding much more in the way of parts. These tires were chunking and lasted 8-10 laps total and 80% of a lap before overheating no matter how nice I drove. The power of the car was enough to drive around the issues and ended up taking home 1st place in class this weekend. I have a few of Dallas's arms waiting for the car now that I don't have to worry about the rules.

LetsGetThisDone

iTrader: (1)

The English Racing drag 8 and drag X both use twinscroll hot sides. And I think the X is the fastest in the world. And the 8 is in the seven's along side the other very few 7 second CT9a's.

RSMike

iTrader: (1)

The Racefab sump is a bandaid, i've got logs to show it's still easy to get oil surge with this setup.
I'm working on a different solution at the moment, hopefully will be tested in a few months.

The oil surge isn't generally what kills the engine. The oil surge slowly kills the oil pump, then the poor condition oil pump is what kills the engine.
Make sure to keep an eye on your cold and hot oil pressures (via oil temp). This will indicate when your oil pump is beyond help and needs to be replaced.
If you're currently 85-95 psi oil pressure at 80ºC oil temp, when your pump is dying it will go down to 75psi, 70psi, 65psi etc etc.