Hey guys. I have a couple questions about my recent dyno results. Yesterday I had my Evo 8 on the dyno for a touch up tune because I added an ETS 3.5" front mount and needed my AFR's adjusted to compensate for the increased flow and lower intake charge. Im gonna give you my number then my mods so maybe someone can enlighten me on why horsepower is falling off at 6200.

So the car was tuned on a mustang dyno. The car made 353hp and 325tq at 24.8psi of boost on 93 pump which only tapers down to ~23psi at 7k. There are two runs on the graph, one before the intercooler was added and one after. The higher graphs are after. So anyways, at 6200rpm, hp starts to plateau then decrease to 7k. Now boost is consistent and not falling off. My initial guess is that it is possibly airflow, as the turbo is producing the right pressure, but all that airflow isn't making it to the head in high rpms fast enough or efficiently enough. Here are my mods:

New FP green turbo HTA
Hallman manual boost controller
OEM manifold
OEM o2 housing
Larger lower IC pipe
OEM IC everywhere else
3.25" inlet on turbo with FP inlet pipe and 3.25" AEM dryflow filter
Kelford stage 1 cams (8-tx258) 258/264 duration purchased mid 2009
3" turbo back exhaust, no cat.
780cc injectors
AEM S1 standalone

Please help Is it my cams? Should I be using gsc s1 268/268 for this setup? I do not want to lose bottom or midrange power.

 

First, this is normal for "smaller" turbos. I say "small" because some would call our stock turbos large lol...but that's neither here nor there. Your graph looks similar to other fp greens...including mine. I have hks 272 cams, which are probably not any better than yours, so my power/tq has that same drop off...

The high rpm power drop is related to the back pressure the turbo produces. All that higher-rpm exhaust gas has to exit thru the tiny oem turbine housing...hence, back pressure. This is why there is a lot of fuss over what cams we all use. The cams help the head flow more air, but that air still has to exit thru the same turbine housing. The turbine wheel also plays a part, which is why the FP turbos can outflow the stock turbo even in the same housings.

Your cams play a part in that drop off...not very familiar with kelford 264s, but a longer duration and higher lift cam will help a bit with the top end torque (and power). But in the end, the turbine housing/wheel can only flow so much...which leads you into the balancing act of turbo selection...

 

Your stock FMIC is likely limiting the top power -- but an HTA green should have ZERO problem keeping a solid flat boost of 25 psi.

 

He says he has a 3.5" ETS intercooler.

I am going with small cams and possibly the stock intake manifold working against them (high velocity with smaller cams and stock everything else).

Aaron

 

+1 I agree with this - it's normal.

 

Graph looks pretty normal to me. Why did you go with the AEM standalone?

 

+1 graph doesnt look bad i would port manifold and turbine housing to free up the exhaust some cams would help also