Hey guys, I was experiencing some overboosting issues previously, my goal was 8Ib but I was hitting 10 on just the wastegates, so I just swapped them out for Forge Actuators with the green (5-10psi) springs, with 3/4 hole preload. (Took like 10 hours lol.. horrible)

Im still hitting almost 10psi with just wastegates. Could it be that my 2.5" downpipes and 2.5" APS exhaust are causing me to overboost?

Thank you,
Aaron

 

Eh, I overboost to about 9.9psi on my high boost setting . . . fuel cut is set to 10.2psi, I've never gone higher than 9.9, AND my EVC6 is set to "target boost" only 8psi on my high boost Map.

I wouldn't be too worried, it's torque that kills motors.

 

Hmmm... you have 2.5" downpipes? I knock like crazy at that high boost so I need to tweak my tune then I guess.. at least swapping actuators got rid of my weird boost curve.. boosts like crazy now haha

 

no wonder hondas last forever

 

 

You're getting knock? Ummm not good. I think you should let Drew's tuner take a look at your car man . . ..

 

thats great

 

hahaha thats a good one lol

 

My timing and fuel maps were tuned for 8psi, so if its overboosting to 10psi that would mean a much greater chance of detonation, who is drews tuner?

Can anyone verify that too little backpressure would mean overboost? I think it makes sense, since theres less backpressure going straight out the exhaust then going out the wastegate first, so even when the wastegates are fully open, the exhaust would still be spooling the turbo, creating more boost. true or false? :0) Just a thought.

Edit: Ive been reading some other forums and it seems that is indeed the case of too little backpressure...

 

can someone who knows what they are talkin about please give me some input

I need to figure out how to make some back pressure with my setup I suppose... so I can have some control over this boost.

Could I somehow make a shim or something to insert between my downpipe and exhaust to create some back pressure? Maybe to restrict the 2.5" piping by 1/4 or 1/2 and inch?

Thanks for any input... not sure which direction to go from here.

 

The best way would be to retune your car. If you have a utec just make a second map for the higher boost. Did this start with the onset of colder weather? I never had any problems with the stock aps actuators maintaining 9psi until 1 went bad. Now I have the same acuators as you and I have to readjust them because they aren't making enough boost. You can alway add more fuel on the top end or pull 1 or 2 degrees of timing.

 

If you want a quick and dirty test - throw your stock cats on. Instant backpressure... If you're still overboosting, then it's something else.

Good luck.

 

no way to, i have the aps downpipes :|

 

what exhaust?

 

Oh that's right... Nevermind. I forgot that the exhaust side of the APS turbos didn't allow for stock cats... Internal wg FTL J/K

 

Yes, back pressure plays a huge part in keeping boost down!! A lot of backpressure will help push the WG valve open earlier. Also the larger the WG valve, the more that backpressure plays. For example on some cars that we build with 60 mm gates, if we put a 20 psi spring in them, base boost will be 14 psi with some back pressure.... and 20 without any.

 

if you have the 2.5" pipes the stock cats will swap directly in. If you run the 3.5" pipes then they won't

 

No, these are the 2.5" downpipes from the old tuner kit, not the ones that allow a cat or testpipe to be attached :0(

 

exhaust silencers would build bp right??

 

yea I suppose, I only want a slight bit, maybe cut my 2.5" pipes down to 2.25" or 2", that should do the trick, when I had dual 2" it seemed good... damnit lol never should have switched.

Wonder if they make universal exhaust silencers that could fit my APS 2.5" exhaust