Just completed GT3071 .63. Surge?

[momento1]

Hi guys,

just finished my upgrade to the S2 with the following goodies:

GT3071 .63 and 440cc injectors (turbo and injectors provided when i purchased from previous owner)
Wagner exhaust manifold, reverse intake and intercooler
ECU chip was provided from the previous owner which i think came from Bram on here (see this thread i found, http://www.s2forum.com/forum/showthr...highlight=sale)

so basically the car goes really well with overboosting of around 28psi and then holding 25psi,
but obviously as i always suspected, it can surge every now and then.

My question is, from others experience, am i best of porting/flowing the head to try and eliminate the surge, or go straight to 7a cams? Or do i go both?

how about ADU cams??

im concerned the 7a cams may make it pretty poor down low, cause at the moment its great.

Or maybe there is another option that someone has had success with that i havent been able to find by searching the forum??

Also does anyone know if Bram still circulates on the forum as i just want to pick his brains a little about his tune.

Cheers

[jade]

ADU cams will not help, Better changing for a .82 exh housing I think

I run the same setup as you with ADU cams once it surged in higher gears , do you have a 3" Exhaust ?

[Error404]

Go straight for the .82 and get some port work done too

[jade]

As far as I am aware at those power levels porting will not do much

[newsh]

PRJ recommends the 7A cams and says don't port. I've not tried them yet, I had a 7A Ex cam in when the car had RS2 manifolds and I didn't like it. Mihnea mapped my car around the surge, it was pretty good but I've just changed to 5 coils and need it mapping again..

[jade]

PRJ recommends the 7A cams and says don't port. I've not tried them yet, I had a 7A Ex cam in when the car had RS2 manifolds and I didn't like it. Mihnea mapped my car around the surge, it was pretty good but I've just changed to 5 coils and need it mapping again..

Makes sense achieving the same thing, later boost and more top end and easier to change

[momento1]

yes i have full 3 inch exhaust.

can i straight swap to a .82 housing? do the .82 housings come to suit the wagner manifold with a K flange?

so i guess my options really are as follows:

1. swap out to a .82 housing and get slower spool but better up top and no surge

or

2. drop in 7a cams and get crappy low end but better up top and no surge...

or

3. get the tune remapped around the surge (however this option is by far the hardest as we have no experienced tuners down under with this car/ecu etc)

geez decisions decisions?????

[A80Avant]

As I had the same setup if I would do it again I'd port the head and use larger valves. I wouldn't go .82 as the lag is significantly different than now and you may not like it. I'd port the head and reduce the surge by not going full throttle from very low revs.

[momento1]

hmmm so porting is still an option then??

oversize valves also??

geez while im at it i may as well do rods also... hehehe
it never ends..

[popdemonic]

yes,i think it's the combo since you need to remove the head off anyway.
i would do the P&P if you're going to the oversize valves.for the bottom end,if i'm not
going to replace the bearings i might be not considering on upgrading the rods.
but if money is not your bigger problem than the surge issue,i'd do it all at once.

[Jamo]

I would not use oversize valves in a car, use back cut valves and porting. Larger valves doesn't mean more flow, you want a good port job to keep air speed up.

Ask JP to sort you out ( get well soon ).

[Error404]

Increasing the VE is only going to help - not sure it would "solve" it though. IIRC JP said it makes a real difference.
No point mapping around it IMHO as you may as well have the larger turbine.

[momento1]

Ok so porting the head is a solid option here. Im willing to go that step.

Is it worth trying that first before going 7a cams??
Or do i just bite the bullet and do the cams as well!!??

[Jamo]

Depends you ideally need a remap for either option. I'd myself try the cams 1st as porting is engine apart.

[DJones]

Depends you ideally need a remap for either option. I'd myself try the cams 1st as porting is engine apart.

Jamo is right for best results.

Mine has ported head 7A ex cam with .6 housing and had surge, now has .8 housing and can still induce surge.

BB turbo's are just so efficient..