I've tried to look this up, but didn't find anything pertaining to my situation, so I'll make this quick. I wasn't happy with my HP so I made many mods on my Evo 9 MR recently. I bought the car with E85, 3"DP exhaust, and Injen UICP/LICP/air intake. I made some mods to it, and unfortunately, I've lost quite a bit of response in doing so. I know this is normal, but I feel that the spool doesn't kick in until 4000 rpms (the gauge says the boost kicks in at 3400 or so, but I don't feel the power until 4000, whereas stock I felt it at 3300-3400). Is this normal? I have over 400hp now and I have a couple theories as to why this happens:

1) The 3.5" ETS Intercooler takes longer for airflow to circulate vs the stock one
2) I changed the turbo to a BBK Full
3) I ported the throttle body and intake manifold but not the exhaust manifold and turbo hotside
4) I changed to a 3 port Boost solenoid vs. 2 port stock.

Those were the major changes I made in the vehicle recently and I feel that my third theory is most likely the problem, but I don't know.

Do you think I have to port the exhaust manifold and the exhaust housing on the turbo in order for the airflow to balance out? Or will that just worsen my response? I miss the responsiveness that I had when it was stock (low end power), even though I'm pleased with the higher RPM HP. Thanks for any insight!

 

if I had to guess, id say it was a combination of the upgraded turbocharger, coupled with the larger intercooler.

 

Just increase the spring pressure that the adjustable WG actuator exerts on the WG flapper valve. Your other theories are a hair off the mark IMO. Just increase WG spring pressure to improve turbocharger response and reduce spool up time.

Your BBK-Full should spool up just about as quick as your stock IX turbo, I think. But, you are going to have to tinker with the preload adjustment. Did you have your car retuned after the mods? Incidentally, who tuned it? Incidentally are you using the stock metal DV?

 

#2 is where you lost the spool, bigger turbo=more lag

 

It's not a big diff on the BBK full. I actually think its the same as stock on my car.

OP: who tuned it after the install, what did they say?
Also, yeah, I would have ported that stuff. Extra ponies from air flow lost.

 

I went back from a 3.5 nisei FMIC to the stock unit and the turbo response is back, so the larger intercooler plays a major role IMHO

 

This has been my experience on other vehicles, but it depends on the size of the turbo/FMIC

 

Sounds normal to me...Even though the BBK does have great response, you're still gonna lose 2-300rpm of spool. That, coupled with the fmic loss is probably what you're feeling.

 

My understanding of things is that it doesn't necessarily have to be that way with this setup though. with the 3-port, you may be able to gain some of that back via tuning for it. When you switched over to the 3-port, did you retune for it? What changes (if any) were made after the new hardware went on?

 

First of all, thanks everyone for your input!

I believe that Sparky might be right on because after all the installations, my tuner said that while he was tuning the Evo, he couldn't max out the hp like he wanted to because the stock internal wastegate actuator wasn't holding boost properly at higher RPM's (but I didn't mention it because I thought that'd only affect HP, not response time). Therefore, I ordered an aftermarket IWA and am waiting on it. I wonder if the response will really improve all that much after I get it (he did say he'd be able to get about 40 more hp with a new IWA and bring the power band over more towards the middle range which seems promising, but would response time be affected this much from it?), because if it doesn't, then I'm considering going back to the stock intercooler. I definitely did notice a small loss of response when I upgraded to the 3.5" ETS intercooler and thought that perhaps it'd get better after a tune, but it didn't (and now I'm troubleshooting because I waited to get everything in my car before spending $ on a tune, y'know?). At this rate, I think maybe going back to the stock intercooler for better response would be worth the California Summertime heat soak, do you all agree?

To answer your question Sparky, I am currently using a stock diverter valve. Do you recommend I upgrade it? What are the benefits?

Lastly, I'm glad to hear that you all don't think it has anything to do with the ported intake manifold because I know that when you port it, you move the power over to the higher band. I am planning on porting the turbo hotside when I get a chance to get a few more hp, but what good is hp when it takes an eon for the spool to kick in? LOL! All those V8's are laughing at me right now....sigh.

Thanks a lot for everyone's input! I value everyone's insightful wisdom!!! Cheers

 

Hmmm. Can you get a hold of a MBC and install it temporarily just so we can sort out your slow boost and the loss of midrange torque. Afterwords you can always switch back to the BCS and ECU controlled boost. It shouldn't be all that difficult if you are reasonably handy with tools and willing to work on your car some?

 

stock DV is capable. i think the bigger IC is making it lag a bit more. takes more time for air pressure to build up. but it'll be fine if u can get the wga thing to work properly. the bbk full i've read it spools pretty fast.

 

boost leak test?

 

OP are you running a cat on your car?

 

I just ordered an ETS 3.5" core. Wonder how noticeable the lost in spool will be.