924Board.org

[Kenodog]

Mulling things over in my mind and I just cant decide if we should use the stock exhaust manifold and turbo or go a bit more exotic and build a runner type like Flosho's and use a T28. I guess what I need an answer for is just how much HP can you get from a stock turbo/manifold before it becomes a power bottleneck ?

Just for reference the rest of the engine will be:
Stoker/knife edged crank
88mm pistons
Ported and polished head with the big valve kit
Megasquirt 3 with all the bells and whistles
Either A/W or FMIC and between 12-15 psi

Im not really looking for 'maybes' or 'it shoulds', i would like to hear from people that have done major mods to a 931 and know first hand.

Thanks a bunch,Leigh
_________________
1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

[Khal]

Joakim put down 374hp on an engine dyno with the stock exhaust manifold. Plenty.
_________________
'80 924 Turbo

[WEASEL149]

[Cedric]

Its a nice machine, its just been in the dyno with new version ITB.

It made good power, I can ask him for a dyno sheet. It was some really nice numbers, like 200hp at 3500 rpm and onwards to the big numbers. This is though measured in engine test cells at statical load points. So not exactly comparable to rolling road acceleration. Pretty hard test to punish the engine for so much time at each load point. It would hurt to see my engine being tested like that with glowing exhaust at 7300rpm
_________________
1980 924 Turbo
www.instagram.com/garagecedric/

[Raceboy]

Stock manifold is ok if you can live with the weird TB position. I chose to do custom manifold because of ITB's and best throttle response on the GULF car but on my red 924 I used stock 924 manifold (not 931 one) and it makes close to 300 hp now with some help of Xylene
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

[Kenodog]

Not the intake manifold Raceboy the exhaust manifold.
_________________
1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

[Khal]

[Raceboy]

No difference, I'm using stock 924 NA exhaust manifold also. And it is better design than 931 unit. NA manifold has 1+4 and 2+3 pulses separated where 931 one is just a plain jane log-style one.
NA one is stronger also but problem is that it has smaller ports than 931 ones.
So the only truly viable option is to make a custom exhaust manifold when it comes to 931. I chose this way because while it flows enough, the transient reponse sucks with it and I really hate the cramped placement of components. I cannot afford to waste several hours when I want to change the oil supply line or something alike on the race-car.

With custom manifold it is a no-brainer to access everything, get better throttle response and of course, power.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche