BC 272 cams on a stock turbo S13/SR20

[imaboa]

Has anyone ever installed a set of BC 272 cams on an SR20 with a stock turbo?

I'm having a really strange problem, and I'm wondering if the turbo being so small is causing my problem.

[EDacIouSX]

um. how about you explain the problem first? and i doubt it is related to having a small turbo...

[Monooxide]

Hopefully your weird problem isn't bad spool up and less low-end power. Because that is one hundred percent normal.

If your down on power up top check your Mechanical and Electrical timing.

[SoguRacing]

i bet it hesitates when he punches it because the ecu isn't tuned for that amount of valve overlap. haha

[dangarnett]

I've been having a issue with the BC 272 cams also. It seems the BC cams have a degreeing problem so you need adjustable cam gears to set them right.
check this post about #102
http://zilvia.net/f/tech-talk/124925-gt2871-users-sr-motor-4.html

ams also did a cam test and came up with the same issue
Ams Evo Cam Test - evolutionm.net (http://forums.evolutionm.net/evo-engine-turbo-drivetrain/343818-ams-evo-cam-test.html)

[imaboa]

Here's a quick overview of the problem:

and it's probably not because its got a stock ecu...

Car:
Ported Head
HD Springs / Retainers
BC272's, HKS Cam gears set to 0
ARP Headstuds
Stock bottom end
Spearco Air to Air Intercooler, 2.5" IC Piping
Haltech Engine Management, Map Sensor Based
3" DownPipe to open exhaust
740cc Injectors

When I first cranked the car prior to putting it on the dyno, I typically work to get the fuel maps in the "ballpark", so the AFs are 14:1's everywhere that I can free rev the car. This at least makes the cars driveable to the point you can get them on the dyno. So, I am working on the fuel map and notice that the inlet air temps are in the 140s degF (ambient was only about 60 that day). I recalibrated the sensor, thinking maybe the calibration was off, only to touch the intercooler piping and almost get burned.

I have two basic issues:
- Compressor Surge @ idle. This can be somewhat taken care of by disconnecting the WG actuator arm, and allowing the WG to be open (this shouldnt be the case, since the wg is always closed until you reach at least the wg spring pressure)
- Elevated IAT's @ idle, typically I dont recall ever seeing temps too much over ambient at idle in most turbo cars

I have verified the following:
- Ignition timing is set at 15 deg, and synched with the haltech
- Cam timing in reference to TDC is correct
- Oil Flow into and out of the Turbo
- Coolant Flow into and out of the turbo
- I have tested two different turbos, both with the same results

Any opinions?

[smelly240]

sounds a lot like you're having some sort of crazy ignition retard happening there. seen it happen before with a stock crank pulley (pulley spun inside of the outer section - and when he thought it was in time it was really retarded 10 deg).

be sure the crank pulley is AT tdc when ur piston #1 is at TDC. this has become increasingly common.

also - you'll see poor results with a t25 on those cams and that headwork.

[imaboa]

Crank Pulley lines up with the 0 Deg. mark when the #1 is at TDC

I would have agreed with the ignition timing thing, but the EGT's are only about 400-500 Deg @ idle.

[Monooxide]

Cams arent installed correctly and the overlap is huge and a lot of exhaust is entering the intake manifold?

[93 Sr Hatch]

the 280 cams seem to be a little big for a stock t25. but im only running 260's with a gt28 so what do i know lol

[imaboa]

I checked the cam install, it is correct.

Both cams are zeroed out. 11 Chain links in between the marks on the cam sprockets, the pin on the exhaust cam is @ 12oclock, and the pin on the intake cam is at 10oclock when the motor is at #1tdc.

I even checked to make sure that the cams werent put in backwards (intake cam on the exhaust side...).

I figured anything was possible.

[Autobacs]

There should be 10 chain links between the marks on the cam sprockets. Looks like you jumped a chain link.

[whitesileighty]

should be 9 links BETWEEN the marks. 11 links if you count the marked chain links.

[Z33dori]

timing is off

[S13 curtis]

damn bro you are moving way tooo much air for that tiny t25. it should spool fast and probly make over 250+whp. but u will def have better results then some stock ass sr.

you will probly overspin that turbo.